U.S. patent application number 14/399793 was filed with the patent office on 2015-05-28 for biogenic activated carbon and methods of making and using same.
The applicant listed for this patent is BIOGENIC REAGENT VENTURES, LLC. Invention is credited to Daniel J. Despen, James A. Mennell.
Application Number | 20150144831 14/399793 |
Document ID | / |
Family ID | 49551221 |
Filed Date | 2015-05-28 |
United States Patent
Application |
20150144831 |
Kind Code |
A1 |
Mennell; James A. ; et
al. |
May 28, 2015 |
BIOGENIC ACTIVATED CARBON AND METHODS OF MAKING AND USING SAME
Abstract
Biogenic activated carbon compositions disclosed herein comprise
at least 55 wt % carbon, some of which may be present as graphene,
and have high surface areas, such as Iodine Numbers of greater than
2000. Some embodiments provide biogenic activated carbon that is
responsive to a magnetic field. A continuous process for producing
biogenic activated carbon comprises countercurrently contacting, by
mechanical means, a feedstock with a vapor stream comprising an
activation agent including water and/or carbon dioxide; removing
vapor from the reaction zone; recycling at least some of the
separated vapor stream, or a thermally treated form thereof, to an
inlet of the reaction zone(s) and/or to the feedstock; and
recovering solids from the reaction zone(s) as biogenic activated
carbon. Methods of using the biogenic activated carbon are
disclosed.
Inventors: |
Mennell; James A.;
(Dellwood, MN) ; Despen; Daniel J.; (Minneapolis,
MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BIOGENIC REAGENT VENTURES, LLC |
Minneapolis |
MN |
US |
|
|
Family ID: |
49551221 |
Appl. No.: |
14/399793 |
Filed: |
May 7, 2013 |
PCT Filed: |
May 7, 2013 |
PCT NO: |
PCT/US13/39981 |
371 Date: |
November 7, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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|
61643741 |
May 7, 2012 |
|
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|
61721827 |
Nov 2, 2012 |
|
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61737514 |
Dec 14, 2012 |
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Current U.S.
Class: |
252/62.55 ;
252/62.51R; 423/448; 502/401 |
Current CPC
Class: |
C01B 32/184 20170801;
B01J 20/28009 20130101; B01J 20/046 20130101; B01J 20/02 20130101;
Y02E 60/36 20130101; B01J 20/20 20130101; B01J 20/28066 20130101;
C10B 57/10 20130101; C10B 53/02 20130101; B01J 20/0225 20130101;
B01J 20/0288 20130101; C01B 32/39 20170801; Y02C 20/40 20200801;
C10B 39/02 20130101; Y02E 50/10 20130101; B01J 20/043 20130101;
B82Y 30/00 20130101; B01J 2220/485 20130101; Y02E 50/30 20130101;
B01J 20/041 20130101; B01J 20/3078 20130101; B01J 20/22 20130101;
B01J 20/10 20130101; B82Y 40/00 20130101; C01B 32/336 20170801;
B01J 20/12 20130101; C10B 57/005 20130101; B01J 20/06 20130101;
Y02P 20/145 20151101 |
Class at
Publication: |
252/62.55 ;
502/401; 252/62.51R; 423/448 |
International
Class: |
B01J 20/22 20060101
B01J020/22; B01J 20/28 20060101 B01J020/28; B01J 20/06 20060101
B01J020/06; B01J 20/02 20060101 B01J020/02 |
Claims
1. A biogenic activated carbon composition comprising, on a dry
basis, about 55 wt % or more total carbon, about 15 wt % or less
hydrogen, and less than or equal to about 1 wt % nitrogen; wherein
said activated carbon composition is characterized by an Iodine
Number higher than about 500, and optionally wherein said
composition is responsive to an externally applied magnetic
field.
2. (canceled)
3. The biogenic activated carbon composition of claim 1, wherein
said composition comprises at least about 75 wt %, at least about
85 wt %, or at least about 95 wt % carbon on a dry basis.
4. The biogenic activated carbon composition of claim 1, wherein
said composition comprises less than or equal to about 0.5 wt %
nitrogen on a dry basis.
5. The biogenic activated carbon composition of claim 1, wherein
said composition comprises less than or equal to about 5 wt %
hydrogen on a dry basis.
6. The biogenic activated carbon composition of claim 1, wherein
said composition further comprises oxygen.
7. The biogenic activated carbon composition of claim 6, wherein
said composition comprises between about 1 wt % and about 10 wt %
oxygen on a dry basis.
8. The biogenic activated carbon composition of claim 1, wherein
said composition comprises about 0.5 wt % or less phosphorus on a
dry basis.
9. The biogenic activated carbon composition of claim 1, wherein
said composition comprises about 0.2 wt % or less sulfur on a dry
basis.
10. The biogenic activated carbon composition of claim 1, wherein
said composition further includes an additive selected from an
acid, a base, a salt, a metal, a metal oxide, a metal hydroxide, a
metal halide, iodine, an iodine compound, or a combination
thereof.
11. The biogenic activated carbon composition of claim 10, wherein
said additive is selected from the group consisting of magnesium,
manganese, aluminum, nickel, iron, chromium, silicon, boron,
cerium, molybdenum, phosphorus, tungsten, vanadium, iron chloride,
iron bromide, magnesium oxide, dolomite, dolomitic lime, fluorite,
fluorospar, bentonite, calcium oxide, lime, sodium hydroxide,
potassium hydroxide, hydrogen bromide, hydrogen chloride, sodium
silicate, potassium permanganate, organic acids, iodine, an iodine
compound, and combinations thereof.
12. The biogenic activated carbon composition of claim 10, wherein
said additive is magnetic or includes a magnetic component.
13. The biogenic activated carbon composition of claim 1, wherein
said composition further includes iron.
14. The biogenic activated carbon composition of claim 13, wherein
said iron is present in said composition from about 0.0001 wt % to
about 1 wt %, from about 0.1 wt % to about 0.5 wt %, from about 0.5
wt % to about 5 wt %, or from about 1 wt % to about 2 wt % on a dry
basis.
15. The biogenic activated carbon composition of claim 1, wherein
said composition is characterized by an Iodine Number of at least
about 1000, at least about 1500, at least about 2000, or from about
2000 to about 2250.
16. The biogenic activated carbon composition of claim 1, wherein
said composition is characterized by a surface area of at least
about 1000 m2/g, at least about 1500 m2/g, or at least about 2000
m2/g.
17. The biogenic activated carbon composition of claim 1, wherein
said composition is in powdered form, granular form, extruded form,
or in structural object form.
18. The biogenic activated carbon composition of claim 1, wherein
said composition has an Abrasion Number from about 20% to about
99%.
19. (canceled)
20. (canceled)
21. (canceled)
22. A biogenic activated carbon composition comprising, on a dry
basis, about 55 wt % or more total carbon, about 15 wt % or less
hydrogen, less than or equal to about 1 wt % nitrogen, and from
about 0.0001 wt % to about 5 wt % iron; wherein at least a portion
of said carbon is present in the form of graphene, wherein said
activated carbon composition is characterized by an Iodine Number
higher than about 500, and wherein said composition is responsive
to an externally applied magnetic field.
23. A biogenic activated carbon composition comprising, on a dry
basis, about 55 wt % or more total carbon, about 15 wt % or less
hydrogen, less than or equal to about 1 wt % nitrogen, and from
about 0.1 wt % to about 5 wt % iron; wherein said activated carbon
composition is characterized by an Iodine Number higher than about
500, and wherein said composition is responsive to an externally
applied magnetic field.
24. (canceled)
25. (canceled)
26. (canceled)
27. (canceled)
Description
PRIORITY CLAIM
[0001] This application is a 35 USC .sctn.371 U.S. National Stage
Application of International Patent Application No.
PCT/US2013/039981, filed May 7, 2013, entitled "BIOGENIC ACTIVATED
CARBON AND METHODS OF MAKING AND USING SAME" which claims the
priority benefit of U.S. Provisional Patent Application No.
61/643,741, filed on May 7, 2012; U.S. Provisional Patent
Application No. 61/721,827, filed on Nov. 2, 2012; and U.S.
Provisional Patent Application No. 61/737,514, filed on Dec. 14,
2012, each of which is hereby incorporated by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present disclosure generally relates to processes,
systems, and apparatus for the production of biogenic activated
carbon, to biogenic activated carbon and to uses of biogenic
activated carbon including emissions control.
BACKGROUND
[0003] Activated carbon was first produced commercially at the
beginning of the 20th century and was used initially to decolorize
sugar, then later to remove taste and odor from water. Granular
activated carbon was first developed for gas masks and has been
used subsequently for a variety of additional purposes such as
solvent recovery and air purification. Processes to produce
activated carbon generally require large energy inputs and suffer
from low yields. Most processes require two distinct steps:
pyrolysis of the carbonaceous raw material followed by activation
of the pyrolyzed solids. Pyrolysis typically involves directly
heating the carbonaceous substrate in a low-oxygen environment.
Activation generally involves application of steam or carbon
dioxide to increase surface area of the pyrolyzed solids.
SUMMARY
[0004] In one embodiment, the present disclosure provides a
biogenic activated carbon composition comprising, on a dry basis,
about 55 wt % or more total carbon, about 15 wt % or less hydrogen,
and less than or equal to about 1 wt % nitrogen; wherein said
activated carbon composition is characterized by an Iodine Number
higher than about 500, and optionally wherein said composition is
responsive to an externally applied magnetic field.
[0005] In another embodiment, the present disclosure provides a
biogenic activated carbon composition comprising, on a dry basis,
about 55 wt % or more total carbon, about 15 wt % or less hydrogen,
and less than or equal to about 1 wt % nitrogen; wherein said
activated carbon composition is characterized by an Iodine Number
higher than about 500, and optionally wherein at least a portion of
said carbon is present in the form of graphene.
[0006] In another embodiment, the present disclosure provides a
biogenic activated carbon composition comprising, on a dry basis,
about 55 wt % or more total carbon, about 15 wt % or less hydrogen,
less than or equal to about 1 wt % nitrogen, and from about 0.0001
wt % to about 5 wt % iron; wherein at least a portion of said
carbon is present in the form of graphene, wherein said activated
carbon composition is characterized by an Iodine Number higher than
about 500, and wherein said composition is responsive to an
externally applied magnetic field.
[0007] In another embodiment, the present disclosure provides a
biogenic activated carbon composition comprising, on a dry basis,
about 55 wt % or more total carbon, about 15 wt % or less hydrogen,
less than or equal to about 1 wt % nitrogen, and from about 0.1 wt
% to about 5 wt % iron; wherein said activated carbon composition
is characterized by an Iodine Number higher than about 500, and
wherein said composition is responsive to an externally applied
magnetic field.
[0008] In another embodiment, the present disclosure provides a
biogenic activated carbon composition comprising, on a dry basis,
about 55 wt % or more total carbon, about 15 wt % or less hydrogen,
and less than or equal to about 1 wt % nitrogen; wherein said
activated carbon composition is characterized by an Iodine Number
higher than about 500, and wherein at least a portion of said
carbon is present in the form of graphene.
[0009] In another embodiment, the present disclosure provides a
biogenic graphene-containing product characterized by an Iodine
Number higher than about 500.
[0010] In another embodiment, the present disclosure provides a
composition comprising graphene, wherein the graphene is derived
from a biogenic activated carbon composition comprising, on a dry
basis, about 55 wt % or more total carbon, about 15 wt % or less
hydrogen, and less than or equal to about 1 wt % nitrogen; wherein
at least a portion of said carbon is present in the form of
graphene.
[0011] In another embodiment, the present disclosure provides a
continuous process for producing biogenic activated carbon, said
process comprising: (a) providing a carbon-containing feedstock
comprising biomass; (b) optionally drying said feedstock to remove
at least a portion of moisture from said feedstock; (c) in one or
more indirectly heated reaction zones, mechanically
countercurrently contacting said feedstock with a vapor stream
comprising a substantially inert gas and an activation agent
comprising at least one of water or carbon dioxide, to generate
solids, condensable vapors, and non-condensable gases, wherein said
condensable vapors and said non-condensable gases enter said vapor
stream; (d) removing at least a portion of said vapor stream from
said reaction zone, to generate a separated vapor stream; (e)
recycling at least a portion of said separated vapor stream, or a
thermally treated form thereof, to said feedstock prior to step (c)
and/or to a gas inlet of said reaction zone(s); and (f) recovering
at least a portion of said solids from said reaction zone(s) as
biogenic activated carbon.
[0012] In another embodiment, the present disclosure provides a
continuous process for producing biogenic activated carbon, said
process comprising: (a) providing a starting carbon-containing
feedstock comprising biomass; (b) optionally drying said
carbon-containing feedstock to remove at least a portion of
moisture therefrom; (c) in one or more indirectly heated reaction
zones, mechanically conveying said feedstock and countercurrently
contacting said feedstock with a vapor stream comprising a
substantially inert gas and an activation agent including at least
one of water or carbon dioxide, to generate solids, condensable
vapors, and non-condensable gases, wherein said condensable vapors
and said non-condensable gases enter said vapor stream; (d)
removing at least a portion of said vapor stream from said reaction
zone, to generate a separated vapor stream; (e) introducing a
carbon-containing liquid or vapor stream from an external source to
said feedstock prior to step (c) and/or to a gas inlet of said
reaction zone(s); and (f) recovering at least a portion of said
solids from said reaction zone(s) as biogenic activated carbon.
[0013] In another embodiment, the present disclosure provides a
continuous process for producing graphene-containing biogenic
activated carbon, said process comprising: (a) providing a starting
carbon-containing feedstock comprising biomass; (b) optionally
drying said carbon-containing feedstock to remove at least a
portion of moisture from said carbon-containing feedstock; (c) in
one or more indirectly heated reaction zones, mechanically
conveying said feedstock and countercurrently contacting said
feedstock with a vapor stream comprising a substantially inert gas
and an activation agent including at least one of water or carbon
dioxide, to generate solids, condensable vapors, and
non-condensable gases, wherein said condensable vapors and said
non-condensable gases enter said vapor stream; (d) removing at
least a portion of said vapor stream from said reaction zone, to
generate a separated vapor stream; (e) recycling at least a portion
of said separated vapor stream, or a thermally treated form
thereof, to said feedstock prior to step (c) and/or to a gas inlet
of said reaction zone(s); and (f) recovering at least a portion of
said solids from said reaction zone(s), wherein said solids include
graphene-containing biogenic activated carbon.
[0014] In another embodiment, the present disclosure provides a
continuous process for producing graphene-containing biogenic
activated carbon, said process comprising: (a) providing a starting
carbon-containing feedstock comprising biomass; (b) optionally
drying said carbon-containing feedstock to remove at least a
portion of moisture from said feedstock; (c) in one or more
indirectly heated reaction zones, mechanically conveying said
feedstock and countercurrently contacting said feedstock with a
vapor stream comprising a substantially inert gas and an activation
agent comprising at least one of water or carbon dioxide, to
generate solids, condensable vapors, and non-condensable gases,
wherein said condensable vapors and said non-condensable gases
enter said vapor stream; (d) removing at least a portion of said
vapor stream from said reaction zone, to generate a separated vapor
stream; (e) recycling at least a portion of said separated vapor
stream, or a thermally treated form thereof, to said feedstock
prior to step (c) and/or to a gas inlet of said reaction zone(s),
to increase the surface area of carbon in said solids; and (f)
recovering at least a portion of said solids from said reaction
zone(s) as biogenic activated carbon, wherein said biogenic
activated carbon comprises, on a dry basis, about 55 wt % or more
total carbon, about 15 wt % or less hydrogen, and less than or
equal to about 1 wt % nitrogen, wherein at least a portion of said
biogenic activated carbon is present in the form of graphene,
wherein said biogenic activated carbon composition is characterized
by an Iodine Number higher than about 500, and wherein said
biogenic activated carbon is responsive to an externally applied
magnetic field.
[0015] In another embodiment, the present disclosure provides a
method of reducing or removing at least one contaminant from a
gas-phase emission stream, said method comprising: (a) providing a
gas-phase emissions stream comprising at least one contaminant; (b)
contacting the gas-phase emissions stream with an additive and
activated carbon particles comprising a biogenic activated carbon
composition to generate contaminant-adsorbed particles; and (c)
separating at least a portion of said contaminant-adsorbed
particles from said gas-phase emissions stream to produce a
contaminant-reduced gas-phase emissions stream.
[0016] In another embodiment, the present disclosure provides a
method of using a biogenic activated carbon composition to reduce
mercury emissions, said method comprising: (a) providing a
gas-phase emissions stream comprising mercury; (b) contacting the
gas-phase emissions stream with activated-carbon particles
comprising a biogenic activated carbon composition comprising iron
or an iron-containing compound to generate mercury-adsorbed carbon
particles; and (c) separating at least a portion of said
mercury-adsorbed carbon particles from said gas-phase emissions
stream using electrostatic precipitation, to produce a
mercury-reduced gas-phase emissions stream.
[0017] In another embodiment, the present disclosure provides a
process for producing energy comprising: (a) providing a
carbon-containing feedstock comprising a biogenic activated carbon
composition; and (b) oxidizing said carbon-containing feedstock to
generate energy and a gas-phase emissions stream comprising at
least one contaminant, wherein the biogenic activated carbon
composition adsorbs at least a portion of the at least one
contaminant.
[0018] In another embodiment, the present disclosure provides a
method of using a biogenic activated carbon composition to purify a
liquid, said method comprising: (a) providing a liquid comprising
at least one contaminant; and (b) contacting said liquid with an
additive and activated-carbon particles comprising a biogenic
activated carbon composition to generate contaminant-adsorbed
carbon particles and a contaminant-reduced liquid.
[0019] In another embodiment, the present disclosure provides a
method of removing at least a portion of a sulfur contaminant from
a liquid, said method comprising: (a) providing a liquid comprising
a sulfur contaminant; and (b) contacting said liquid with an
additive and activated-carbon particles comprising a biogenic
activated carbon composition, wherein after step (b) at least a
portion of the activated carbon particles comprises the sulfur
contaminant.
[0020] In another embodiment, the present disclosure provides a
process to reduce a concentration of sulfates in water, said
process comprising: (a) providing a volume or stream of water
comprising sulfates; and (b) contacting said water with an additive
and activated-carbon particles comprising a biogenic activated
carbon composition.
[0021] In another embodiment, the present disclosure provides a
method of removing a sulfur contaminant from a gas-phase emissions
stream, said method comprising: (a) providing a gas-phase emissions
stream comprising at least one sulfur contaminant; (b) contacting
the gas-phase emissions stream with an additive and
activated-carbon particles comprising a biogenic activated carbon
composition; and (c) separating at least a portion of said
activated-carbon particles from said gas-phase emissions stream
after step (b).
[0022] In another embodiment, the present disclosure provides a
method of reducing or removing one or more contaminants from a gas
or liquid, said method comprising: (a) providing a gas or liquid
stream containing one or more contaminants; and (b) contacting said
gas or liquid stream with a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen, and an Iodine Number of at least about 500, wherein
said composition is responsive to an externally applied magnetic
field.
[0023] In another embodiment, the present disclosure provides a
method of reducing or removing one or more contaminants from a gas
or liquid, said method comprising: (a) providing a gas or liquid
stream containing one or more contaminants; and (b) contacting said
gas or liquid stream with a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen, and an Iodine Number of at least about 500, wherein
at least a portion of said carbon is present in the form of
graphene.
[0024] In another embodiment, the present disclosure provides a
method of reducing or removing a contaminant from a liquid or gas,
said method comprising: (a) obtaining a biogenic activated carbon
composition comprising, on a dry basis, about 55 wt % or more total
carbon, about 15 wt % or less hydrogen, and less than or equal to
about 1 wt % nitrogen, wherein at least a portion of said carbon is
present in the form of graphene; (b) optionally separating said
graphene from said biogenic activated carbon composition; and (c)
contacting the liquid or gas with said graphene, in separated form
or as part of said biogenic activated carbon composition.
[0025] In another embodiment, the present disclosure provides a
method of using graphene, said method comprising: (a) obtaining a
biogenic activated carbon composition comprising, on a dry basis,
about 55 wt % or more total carbon, about 15 wt % or less hydrogen,
and less than or equal to about 1 wt % nitrogen; wherein at least a
portion of said carbon is present in the form of graphene; (b)
optionally separating said graphene from said biogenic activated
carbon composition; and (c) using said graphene, in separated form
or as part of said biogenic activated carbon composition, in an
adhesive, a sealant, a coating, a paint, an ink a composite
material, a catalyst, a catalyst support, a battery electrode, a
fuel cell electrode, a graphene-based circuit or memory system, an
energy storage material or device, a supercapacitor, a sink for
static electricity dissipation, a material or device for electronic
or ionic transport, a high-bandwidth communication system, an
infrared sensor, a chemical sensor, a biological sensor, an
electronic display, a voltaic cell, or a graphene aerogel.
BRIEF DESCRIPTION OF THE FIGURES
[0026] FIG. 1 depicts a multi-reactor embodiment of a system of the
disclosure.
[0027] FIG. 2 depicts a single reactor, multi-zone embodiment of a
system of the disclosure
[0028] FIG. 3 depicts one embodiment of a zero-oxygen continuous
feed mechanism suitable for use in connection with the present
disclosure.
[0029] FIG. 4 depicts another embodiment of a single reactor,
multi-zone biomass processing unit suitable for use in connection
with the present disclosure.
[0030] FIG. 5 depicts one embodiment of a carbon recovery unit
suitable for use in connection with the present disclosure.
[0031] FIG. 6 depicts an embodiment of one embodiment of a
single-reactor biomass processing unit of the present disclosure
with an optional dryer.
[0032] FIG. 7 depicts a pyrolysis reactor system embodiment of the
disclosure with an optional dryer and a gas inlet.
[0033] FIG. 8 depicts an embodiment of a single-reactor biomass
processing unit of the disclosure with a gas inlet and an optional
cooler.
[0034] FIG. 9 depicts a single-reactor biomass processing unit
system embodiment of the disclosure with an optional dryer and
de-aerator, and an inert gas inlet.
[0035] FIG. 10 depicts a multiple-reactor system embodiment of the
disclosure with an optional dryer and de-aerator, and an inert gas
inlet.
[0036] FIG. 11 depicts a multiple-reactor system embodiment of the
disclosure with an optional dryer and cooler, and a material
enrichment unit.
[0037] FIG. 12 depicts a multiple-reactor system embodiment of the
disclosure with an optional dryer, de-aerator, a cooler, and an
inert gas inlet.
[0038] FIG. 13 depicts a multiple-reactor system embodiment of the
disclosure with an optional dryer and de-aerator, an inert gas
inlet, and a cooler.
[0039] FIG. 14 shows dispersion of magnetic particles in a biogenic
activated carbon according to the present disclosure.
[0040] FIG. 15 shows biogenic activated carbon with iron halide
additive prepared according to the present disclosure attracted to
a magnet.
[0041] FIG. 16 depicts change in gas component concentration over
time when passed through a plug of a biogenic activated carbon
according to the present disclosure.
[0042] FIG. 17 depicts adsorption of carbon dioxide over time for a
plug of a biogenic activated carbon according to the present
disclosure.
[0043] FIG. 18 depicts a graph illustrating the effect of retention
time on fixed carbon content of a biogenic activated carbon product
produced according to one embodiment of the present disclosure.
[0044] FIG. 19 depicts a graph illustrating the effect of pyrolysis
temperature on fixed carbon content of a biogenic activated carbon
product produced according to one embodiment of the present
disclosure.
[0045] FIG. 20 depicts a graph illustrating the effect of biomass
particle size on fixed carbon content of a biogenic activated
carbon product produced according to one embodiment of the present
disclosure.
[0046] FIG. 21 depicts a single-reactor biomass processing unit
embodiment of the disclosure for producing biogenic activated
carbon.
[0047] FIG. 22 depicts a two-reactor biomass processing unit
embodiment of the disclosure for producing biogenic activated
carbon.
[0048] FIG. 23 is a transmission electron micrograph of exemplary
activated carbon with an Iodine Number of 2029. The dark, curved
line segments are graphene crystallites.
[0049] FIG. 24 is a transmission electron micrograph of exemplary
activated carbon with an Iodine Number of 2029. The dark, curved
line segments are graphene crystallites.
[0050] FIG. 25 is a transmission electron micrograph of activated
carbon with an Iodine Number of 2029. Parallel lines across image
are atomically thin layers of graphene.
[0051] FIG. 26 is a transmission electron micrograph of activated
carbon with an Iodine Number of 2029. Dark, curved line segments
are graphene crystallites.
[0052] FIG. 27 is a transmission electron micrograph of activated
carbon with an Iodine Number of 716. Parallel lines across image
are atomically thin layers of graphene.
[0053] FIG. 28 is a transmission electron micrograph of activated
carbon with an Iodine Number of 716. Parallel lines across image
are atomically thin layers of graphene within graphite.
[0054] FIG. 29 is a transmission electron micrograph of activated
carbon with an Iodine Number of 716. The roughly square object at
bottom center is zoomed out from FIG. 28. Lighter regions comprise
small graphene crystallites.
[0055] FIG. 30 is a transmission electron micrograph of activated
carbon with an Iodine Number of 716. The small, dark, square object
left of center is the graphite piece from FIGS. 28 and 29. Lighter
regions indicate small graphene crystallites.
[0056] FIG. 31 is a transmission electron micrograph of activated
carbon with an Iodine Number of 806. Parallel lines across image
are atomically thin layers of graphene, while shorter curved
segments are graphene crystallites.
DETAILED DESCRIPTION
[0057] This description will enable one skilled in the art to make
and use the disclosure, and it describes several embodiments,
adaptations, variations, alternatives, and uses of the disclosure.
These and other embodiments, features, and advantages of the
present disclosure will become more apparent to those skilled in
the art when taken with reference to the following detailed
description of the disclosure in conjunction with the accompanying
drawings.
[0058] As used in this specification and the appended claims, the
singular forms "a," "an," and "the" include plural referents unless
the context clearly indicates otherwise. Unless defined otherwise,
all technical and scientific terms used herein have the same
meaning as is commonly understood by one of ordinary skill in the
art to which this disclosure belongs.
[0059] Unless otherwise indicated, all numbers expressing reaction
conditions, stoichiometries, concentrations of components, and so
forth used in the specification and claims are to be understood as
being modified in all instances by the term "about." Accordingly,
unless indicated to the contrary, the numerical parameters set
forth in the following specification and attached claims are
approximations that may vary depending at least upon a specific
analytical technique.
[0060] For present purposes, "biogenic" is intended to mean a
material (whether a feedstock, product, or intermediate) that
contains an element, such as carbon, that is renewable on time
scales of months, years, or decades. Non-biogenic materials may be
non-renewable, or may be renewable on time scales of centuries,
thousands of years, millions of years, or even longer geologic time
scales. Note that a biogenic material may include a mixture of
biogenic and non-biogenic sources.
[0061] For present purposes, "reagent" is intended to mean a
material in its broadest sense; a reagent may be a fuel, a
chemical, a material, a compound, an additive, a blend component, a
solvent, and so on. A reagent is not necessarily a chemical reagent
that causes or participates in a chemical reaction. A reagent may
or may not be a chemical reactant; it may or may not be consumed in
a reaction. A reagent may be a chemical catalyst for a particular
reaction. A reagent may cause or participate in adjusting a
mechanical, physical, or hydrodynamic property of a material to
which the reagent may be added. For example, a reagent may be
introduced to a metal to impart certain strength properties to the
metal. A reagent may be a substance of sufficient purity (which, in
the current context, is typically carbon purity) for use in
chemical analysis or physical testing.
[0062] Graphene is a monolayer of carbon atoms tightly packed into
a two-dimensional honeycomb lattice, and is a basic building block
for graphitic materials of other dimensionalities. Graphene can be
wrapped up into zero-dimensional fullerenes, rolled into
one-dimensional nanotubes, or stacked into three-dimensional
graphite, for example. That is, although graphene is a single layer
of atomic carbon, any number of layers (such as 1, 2, 3, 4, 5, 6,
7, 8, 9, 10 or more) may be present in any particular portion of a
graphene-containing sample. As used herein, "graphene" refers to
graphene in any of its forms, including related sp.sup.2 graphitic
allotropes that are typically planar, although not necessarily
flat, single layers of graphene, and multiple layers of graphene.
In one embodiment, the graphene is a one-atom thick planar sheet of
sp.sup.2-bonded carbon atoms that are in a hexagonal arrangement.
In another embodiment, the graphene is a one-atom thick planar
sheet of sp.sup.2-bonded carbon atoms that are in a hexagonal
arrangement in a honeycomb crystal lattice. In another embodiment,
the graphene has a carbon-carbon bond length of about 0.142 nm.
Unless the context dictates otherwise, all references to graphene
include strictly a single layer as well as multiple layers of
carbon atoms. Also, all references to graphene should be regarded
as interchangeable with "biogenic graphene."
[0063] Biogenic activated carbon has relatively high carbon content
compared to the initial feedstock utilized to produce the biogenic
activated carbon. A biogenic activated carbon as provided herein
will normally contain greater than about half its weight as carbon,
since the typical carbon content of biomass is no greater than
about 50 wt %. More typically, but depending on feedstock
composition, a biogenic activated carbon will contain at least 55
wt %, at least 60 wt %, at least 65 wt %, at least 70 wt %, at
least 75 wt %, at least 80 wt % 85 wt %, at least 90 wt %, at least
95 wt %, at least 96 wt %, at least 97 wt %, at least 98 wt %, at
least 99 wt % carbon.
[0064] Notwithstanding the foregoing, the term "biogenic activated
carbon" is used herein for practical purposes to consistently
describe materials that may be produced by processes and systems of
the disclosure, in various embodiments. Limitations as to carbon
content, or any other concentrations, shall not be imputed from the
term itself but rather only by reference to particular embodiments
and equivalents thereof. For example it will be appreciated that a
starting material having very low initial carbon content, subjected
to the disclosed processes, may produce a biogenic activated carbon
that is highly enriched in carbon relative to the starting material
(high yield of carbon), but nevertheless relatively low in carbon
(low purity of carbon), including less than or equal to about 50 wt
% carbon.
[0065] "Pyrolysis" and "pyrolyze" generally refer to thermal
decomposition of a carbonaceous material. In pyrolysis, less oxygen
is present than is required for complete combustion of the
material, such as less than or equal to about 10%, less than or
equal to about 5%, less than or equal to about 1%, less than or
equal to about 0.5%, less than or equal to about 0.1%, or less than
or equal to about 0.01% of the oxygen that is required for complete
combustion. In some embodiments, pyrolysis is performed in the
absence of oxygen.
[0066] Exemplary changes that may occur during pyrolysis include
any of the following: (i) heat transfer from a heat source
increases the temperature inside the feedstock; (ii) the initiation
of primary pyrolysis reactions at this higher temperature releases
volatiles and forms a char; (iii) the flow of hot volatiles toward
cooler solids results in heat transfer between hot volatiles and
cooler unpyrolyzed feedstock; (iv) condensation of some of the
volatiles in the cooler parts of the feedstock, followed by
secondary reactions, can produce tar; (v) autocatalytic secondary
pyrolysis reactions proceed while primary pyrolytic reactions
simultaneously occur in competition; and (vi) further thermal
decomposition, reforming, water-gas shift reactions, free-radical
recombination, and/or dehydrations can also occur, which are a
function of the residence time, temperature, and pressure
profile.
[0067] Pyrolysis can at least partially dehydrate the feedstock. In
various embodiments, pyrolysis removes greater than about 50%,
greater than about 75%, greater than about 90%, greater than about
95%, greater than about 99%, or more than 99% of the water from the
feedstock.
[0068] As discussed above, some variations of the disclosure are
premised, at least in part, on the discovery that multiple reactors
or multiple zones within a single reactor can be designed and
operated in a way that optimizes carbon yield and product quality
from pyrolysis, while maintaining flexibility and adjustability for
feedstock variations and product requirements.
[0069] Generally speaking, temperatures and residence times are
selected to achieve relatively slow pyrolysis chemistry. The
benefit is potentially the substantial preservation of cell walls
contained in the biomass structure, which means the final product
can retain some, most, or all of the shape and strength of the
starting biomass. In order to maximize this potential benefit, an
apparatus that does not mechanically destroy the cell walls or
otherwise convert the biomass particles into small fines can be
utilized. Various reactor configurations are discussed following
the process description below.
[0070] Additionally, if the feedstock is a milled or sized
feedstock, such as wood chips or pellets, it may be desirable for
the feedstock to be carefully milled or sized. Careful initial
treatment will tend to preserve the strength and cell-wall
integrity that is present in the native feedstock source (e.g.,
trees). This can also be important when the final product should
retain some, most, or all of the shape and strength of the starting
biomass.
[0071] In various embodiments, measures are taken to preserve the
vascular structure of woody feedstock to create greater strength in
biogenic activated carbon products. For example, and without
limitation, in various embodiments the feedstock is prepared by
drying feedstock over an extended period of time, for example over
a period of time of no less than 1 hour, no less than about 2
hours, no less than about 3 hours, no less than about 4 hours, no
less than about 5 hours, no less than about 6 hours, no less than
about 7 hours, no less than about 8 hours, no less than about 9
hours, no less than about 10 hours, no less than about 11 hours, no
less than about 12 hours, no less than about 13 hours, no less than
about 14 hours, no less than about 15 hours, no less than about 16
hours, no less than about 17 hours, no less than about 18 hours, no
less than about 19 hours, no less than about 20 hours, no less than
about 21 hours, no less than about 22 hours, no less than about 23
hours, or no less than about 24 hours, to allow water and gases to
exit the biomass without destroying the vascular structure of the
feedstock. In various embodiments, use of a slow progressive heat
rate during pyrolysis (for example in contrast to flash pyrolysis)
over minutes or hours is used to allow water and gases to exit the
biomass without destroying the vascular structure of the feedstock.
For example and without limitation, a rate of temperature increase
during the pyrolysis step may range from about 1.degree. C. per
minute to about 40.degree. C. per minute, for example about
1.degree. C. per minute, about 2.degree. C. per minute, about
4.degree. C. per minute, about 5.degree. C. per minute, about
10.degree. C. per minute, about 15.degree. C. per minute, about
20.degree. C. per minute, about 25.degree. C. per minute, about
30.degree. C. per minute, about 35.degree. C. per minute, or about
40.degree. C. per minute. In some embodiments, the temperature
increase occurs in a pre-heat zone to produce a preheated
feedstock. In some embodiments, the temperature increase occurs
predominantly or entirely in a pre-heat zone to produce a preheated
feedstock. In some embodiments, the temperature of a preheated
feedstock is increased in a pre-pyrolysis zone. In some
embodiments, the temperature increase occurs at least in part in a
carbonization zone or a pyrolysis zone. In some embodiments, the
temperature increase occurs predominantly or entirely in a
carbonization zone or a pyrolysis zone. In some embodiments, a
preheat zone, pre-pyrolysis zone, carbonization zone or pyrolysis
zone is configured to increase the temperature during pyrolysis
from an initial, low temperature to a final, higher temperature
over time. In some embodiments, the temperature increase is linear
or substantially linear over time. In some embodiments, the rate of
temperature increase increases or decreases over time such that the
temperature during preheating, pre-pyrolysis and/or carbonization
or pyrolysis is at least partially nonlinear, for example
logarithmic or substantially logarithmic for at least a portion of
the preheat, pre-pyrolysis and/or carbonization or pyrolysis step.
In various embodiments, an additive is used prior to drying or
pyrolysis to reduce gas formation that could damage the vascular
structure of the feedstock during pyrolysis. In various
embodiments, prior to pyrolysis, dried feedstock is sized using a
saw or other cutting device designed to be less destructive to the
vascular structure of wood than other sizing approaches such as
chipping or shearing wet wood that fractures wood and decreases its
strength. In such embodiments, a biogenic activated carbon product
has a greater strength index (e.g., CSR value) than a comparable
biogenic activated carbon product not prepared in such a
manner.
[0072] In various embodiments, the feedstock is prepared by milling
biomass to form a plurality of biomass pieces that are
substantially uniform size and substantially uniform shape. For
example and without limitation, biomass can be processed to produce
sawdust of approximately uniform grain size (e.g., mesh size).
Alternatively, biomass can be processed to produce chips having
substantially uniform dimensions (e.g., approximately 1 inch by
approximately 1/2-inch by approximately 1/8-inch pieces). In other
embodiments, feedstock can be prepared by milling biomass to form
lengths of material with substantially uniform width and depth
dimensions or diameters (e.g., wood bars, boards or dowels). In
related embodiments, the lengths of material having substantially
uniform width and depth or diameter can be further milled to
produce feedstock pieces of substantially uniform lengths,
resulting in a feedstock material having substantially uniform size
and shape. For example, wood dowels having a uniform diameter
(e.g., about 11/8 inches) can be cut into pieces of substantially
uniform length (e.g., about 1.5 inches). The resulting feedstock
pieces have a substantially uniform shape (cylinders) and a
substantially uniform size (about 11/8 inch diameter by about 1.5
inch lengths). In some embodiments, a biogenic activated carbon
product prepared from a feedstock consisting of pieces of
substantially uniform shape and size is produced in greater mass
yield than a comparable biogenic activated carbon product prepared
from feedstock pieces of substantially non-uniform shape and/or
size.
[0073] Referring now generally to FIGS. 1 to 13, block flow
diagrams of a several exemplary multi reactor embodiments of the
present disclosure are illustrated. Each figure is discussed in
turn below. It should be appreciated FIGS. 1 to 13 represent some
example embodiments but not all contemplated embodiments of the
present disclosure. As discussed below, various additional
non-illustrated embodiments and combinations of the several
components and features discussed herein are also contemplated. As
will be understood in the discussion below, any of the plurality of
reactors discussed herein can be independent reactors, or
alternatively within a single reactor BPU can include a plurality
of zones, or a combination thereof. It should be appreciated that,
although the figures each illustrate a different alternative
embodiment, all other discussion in this disclosure can apply to
each of the illustrated and non-illustrated embodiments.
[0074] Referring now generally to FIG. 1, a block flow diagram of a
multi reactor embodiment of the present disclosure is illustrated.
This embodiment can utilize two to a plurality of different
reactors. Three reactors are shown in the illustrative embodiment,
however, any different number of reactors could be employed. In one
embodiment, each reactor is connected to at least one other reactor
via a material transport unit 304 (shown in FIG. 3). In one
embodiment, the material transport unit 304 controls atmosphere and
temperature conditions.
[0075] In the illustrated embodiment, the raw material 109, such as
biomass, is optionally dried and sized outside the system and
introduced into the first reactor 100 in a low-oxygen atmosphere,
optionally through the use of a material feed system 108. As
discussed in further detail below and as illustrated in FIG. 3, the
material feed system 108 reduces the oxygen level in the ambient
air in the system to less than or equal to about 3%. The raw
material 109 enters the first reactor 112 via the enclosed material
transport unit 304 after the oxygen levels have been decreased in
the first reactor. In one embodiment, the raw material transport
unit will include an encapsulated jacket or sleeve through which
steam and off-gases from the reactor are sent and used to pre-heat
the biomass either directly or sent to a process gas heater and or
heat exchanger and then sent and used to pre-heat or pyrolize the
biomass.
[0076] In the illustrated embodiment, the raw material 109 first
travels from the material feed system 108 on the material transport
unit 304 into the first reactor of the BPU 112.
[0077] As discussed in more detail below, in one embodiment, the
first reactor 112 is configured to be connected to any other
reactor in the system to recover waste heat 132 and conserve energy
through a suitable waste heat recovery system. In one embodiment,
the waste heat given off in the first reactor 112 is used to
operate a steaming bin or another appropriate heating mechanism
configured to dry raw materials 109 inside or outside of the
system. In various embodiments, other byproducts of the waste heat,
such as a substantially heated inert gas or the like, can be used
elsewhere in the system to further enrich the material at any point
along the process.
[0078] In the illustrated embodiment, the biomass 109 enters the
first reactor 112, wherein the temperature is raised from the range
of about ambient temperature to about 150.degree. C. to a
temperature of about 100.degree. C. to about 200.degree. C. In one
embodiment, the temperature does not exceed 200.degree. C. in the
first reactor 112. As discussed in greater detail below, the first
reactor 112 can include an output mechanism to capture and exhaust
off-gases 120 from the biomass 123 while it is being heated. In one
embodiment, the off-gases 120 are extracted for optional later use.
In various embodiments, the heating source used for the various
zones in the BPU 102 is electrical or gas. In one embodiment, the
heating source used for the various reactors of the BPU 102 is
waste gas from other reactors of the unit 102 or from external
sources. In various embodiments, the heat is indirect.
[0079] Following preheating in the first reactor 112, the material
transport unit 304 passes the preheated material 123 into the
optional second reactor 114. In one embodiment reactor 114 is the
same as reactor 112. In one embodiment where reactor 114 is
different than reactor 112, the material transport unit 304
penetrates the second reactor 114 through a high-temperature vapor
seal system (e.g. an airlock), which allows the material transport
unit 304 to penetrate the second reactor while preventing gas from
escaping. In one embodiment, the interior of the second reactor 114
is heated to a temperature of about 100.degree. C. to about
600.degree. C. or about 200.degree. C. to about 600.degree. C. In
another embodiment, the second reactor 114 includes an output port
similar to the first reactor 102 to capture and exhaust the gases
122 given off of the preheated material 123 while it is being
carbonized. In one embodiment, the gases 122 are extracted for
optional later use. In one illustrative embodiment, the off-gases
120 from the first reactor 112 and the off-gases 122 from the
second reactor 114 are combined into one gas stream 124. Once
carbonized, the carbonized biomass 125 exits the second reactor 114
and enters the third reactor 116 for cooling. Again, the third
reactor can be the same reactor as 112 or 114 or different.
[0080] In one embodiment, when the biogenic activated carbon
product 125 enters the third reactor 116, the carbonized biomass
125 is allowed to cool (actively or passively) to a specified
temperature range to form carbonized biomass 126, as discussed
above. In one embodiment, temperature of the carbonized biomass 125
is reduced in the third reactor under substantially inert
atmospheric conditions. In another embodiment, the third reactor
cools the carbonized biomass 125 with an additional water cooling
mechanism. It should be appreciated that the carbonized biomass 126
is allowed to cool in the third reactor 116 to the point where it
will not spontaneously combust if exposed to oxygenated air. In one
such embodiment, the third reactor 116 reduces temperature of the
carbonized biomass to below 200.degree. C. In one embodiment, the
third reactor includes a mixer (not shown) to agitate and uniformly
cool the carbonized biomass. It should be appreciated that cooling
may occur either directly or indirectly with water or other
liquids; cooling may also occur either directly or indirectly with
air or other cooled gases, or any combination of the above.
[0081] It should be appreciated that in several embodiments (not
shown) one or more additional coolers or cooling mechanisms are
employed to further reduce the temperature of the carbonized
biomass. In various such embodiments, the cooler is separate from
the other reactors 112, 114, 116, along the material transport
system. In some embodiments, the cooler follows the reactors. In
some embodiments, the cooler can be the same as the reactors 112,
114, 116. In other embodiments, the cooler is, for example, a
screw, auger, conveyor (specifically a belt conveyor in one
embodiment), drum, screen, pan, counterflow bed, vertical tower,
jacketed paddle, cooled screw or combination thereof that cools
either directly or indirectly with water or other liquids, or
directly or indirectly with other gases, or combination of the
above. In various embodiments, coolers could include water spray,
cooled inert gas streams, liquid nitrogen, or ambient air if below
ignition temperature. It should be appreciated that heat can be
recovered from this step by capturing the flash steam generated by
the water spray, or the superheated steam generated when saturated
steam is introduced and heated by the carbonized biomass.
[0082] As illustrated in FIGS. 1 and 5, the gas-phase separator
unit 200 includes at least one input and a plurality of outputs.
The at least one input is connected to the exhaust ports on the
first reactor 112 and the second reactor 114 of the BPU 102. One of
the outputs is connected to the carbon recovery unit 104, and
another one of the outputs is connected to collection equipment or
further processing equipment such as an acid hydrogenation unit 106
or distillation column. In various embodiments, the gas-phase
separator processes the off-gases 120, 122 from the first reactor
112 and the second reactor 114 to produce a condensate 128 and an
enrichment gas 204. In various embodiments, condensables may be
used for either energy recovery (134) (for example in the dryer,
reactor or process gas heater), or for other carbon enrichment. In
various embodiments, non-condensables (for example CO) may be used
for energy recovery (134) (for example in a dryer, reactor or
process gas heater), as an inert gas in the process (for example in
the deaeration unit, reactor, BPU or cooler discussed in more
detail below) or for carbon enrichment.
[0083] In various embodiments, the condensate 128 includes polar
compounds, such as acetic acid, methanol and furfural. In another
embodiment, the enrichment gas 204 produced by the gas-phase
separator 200 includes at least non-polar gases, for example carbon
monoxide, terpenes, methane, carbon dioxide, etc. In one
embodiment, the gas-phase separator comprises a fractionation
column. In one embodiment, acetic acid is sent via a line 128 to an
optional acid hydrogenation unit. In another embodiment, methanol
and/or furfural are sent via optional additional line(s) 136 to a
distillation/processing unit 138
[0084] In various embodiments, as discussed in more detail below,
the carbon recovery unit itself has the facility to enrich the
material. In various other embodiments, the material is enriched in
a material enrichment unit separate from the carbon recovery unit.
It should be appreciated that, in some such embodiments, the carbon
recovery unit is a vessel for storing the carbonized material, and
the separate material enrichment unit is the unit in which gases
are introduced to enrich the material.
[0085] In the illustrated embodiment, the carbon recovery unit 500
also enriches the carbonized biomass 126. The carbonized biomass
126 exits the third reactor along the material transport unit 304
and enters the carbon recovery unit 500. In various embodiments, as
illustrated in more detail in FIG. 5 and discussed above, the
carbon recovery unit 500 also includes an input 524 connected to
the gas-phase separator 200. In one embodiment, the enrichment gas
204 is directed into the carbon recovery unit to be combined with
the biogenic activated carbon product 126 to create a high carbon
biogenic activated carbon product 136. In another embodiment, a
carbon-enriched gas from an external source can also be directed to
the carbon recovery unit to be combined with the carbonized biomass
126 to add additional carbon to the ultimate high carbon biogenic
activated carbon product produced. In various embodiments, the
carbonized biomass 126 is temperature-reduced carbonized biomass.
Illustratively, the system 100 can be co-located near a timber
processing facility and carbon-enriched gas from the timber
processing facility can be used as gas from an external source.
[0086] Referring now generally to FIG. 2, a block flow diagram of a
single reactor, multi-zone embodiment of the present disclosure is
illustrated. In the illustrated embodiment, the raw material 209,
such as biomass, is introduced into the reactor 200 in a low-oxygen
atmosphere, optionally through the use of a material feed system
108 already described. As discussed in further detail below, the
material feed system 108 reduces the oxygen level in the ambient
air in the system to less than or equal to about 3%. The raw
material 209 enters the BPU 202 in an enclosed material transport
unit 304 after the oxygen levels have been decreased. In one
embodiment, the material transport unit will include an
encapsulated jacket or sleeve through which steam and off-gases
from the reactor 200 are sent and used to pre-heat the biomass.
[0087] In the illustrated embodiment, the raw material first
travels from the material feed system 108 on the material transport
unit 304 through an optional drying zone 210 of the BPU 202. In one
embodiment, the optional drying zone 210 heats the raw material to
remove water and other moisture prior to being passed along to the
preheat zone 212. In one embodiment, the interior of the optional
drying zone 210 is heated to a temperature of about ambient
temperature to about 150.degree. C. Water 238 or other moisture
removed from the raw material 209 can be exhausted, for example,
from the optional drying zone 210. In another embodiment, the
optional drying zone is adapted to allow vapors and steam to be
extracted. In another embodiment, vapors and steam from the
optional drying zone are extracted for optional later use. As
discussed below, vapors or steam extracted from the optional drying
zone can be used in a suitable waste heat recovery system with the
material feed system. In one embodiment, the vapors and steam used
in the material feed system pre-heat the raw materials while oxygen
levels are being purged in the material feed system. In another
embodiment, biomass is dried outside of the reactor and the reactor
does not comprise a drying zone.
[0088] As discussed in more detail below, in one embodiment, the
optional drying zone 210 is configured to be connected to the
cooling zone 216 to recover waste heat 232 and conserve energy
through a suitable waste heat recovery system. In one embodiment,
the waste heat given off in the cooling zone 216 is used to operate
a heating mechanism configured to dry raw materials 209 in the
optional drying zone 210. After being dried for a desired period of
time, the dried biomass 221 exits the optional drying zone 210 and
enters preheat zone 212.
[0089] In the illustrated embodiment, the dried biomass 221 enters
the first (preheat) zone 212, wherein the temperature is raised
from the range of about ambient temperature to about 150.degree. C.
to a temperature range of about 100.degree. C. to about 200.degree.
C. In one embodiment, the temperature does not exceed 200.degree.
C. in the first/preheat zone 212. It should be appreciated that if
the preheat zone 212 is too hot or not hot enough, the dried
biomass 221 may process incorrectly prior to entering the second
zone 214. As discussed in greater detail below, the preheat zone
212 can includes an output mechanism to capture and exhaust
off-gases 220 from the dried biomass 221 while it is being
preheated. In another embodiment, the off-gases 220 are extracted
for optional later use. In various embodiments, the heating source
used for the various zones in the BPU 202 is electric or gas. In
one embodiment, the heating source used for the various zones of
the BPU 202 is waste gas from other zones of the unit 202 or from
external sources. In various embodiments, the heat is indirect.
[0090] Following the preheat zone 212, the material transport unit
304 passes the preheated material 223 into the second (pyrolysis)
zone 214. In one embodiment, the material transport unit 304
penetrates the second/pyrolysis zone through a high-temperature
vapor seal system (such as an airlock, not shown), which allows the
material transport unit 304 to penetrate the high-temperature
pyrolysis zone while preventing (or minimizing) gas from escaping.
In one embodiment, the interior of the pyrolysis zone 214 is heated
to a temperature of about 100.degree. C. to about 600.degree. C. or
about 200.degree. C. to about 500.degree. C. In another embodiment,
the pyrolysis zone 214 includes an output port similar to the
preheat zone 212 to capture and exhaust the gases 222 given off of
the preheated biomass 223 while it is being carbonized. In one
embodiment, the gases 222 are extracted for optional later use. In
one illustrative embodiment, the off-gases 220 from the preheat
zone 212 and the off-gases 222 from the pyrolysis zone 214 are
combined into one gas stream 224. Once carbonized, the carbonized
biomass 225 exits the second/pyrolysis zone 214 and enters the
third/temperature-reducing or cooling zone 216.
[0091] In one embodiment, when the carbonized biomass 225 enters
the cooling zone 216, the carbonized biomass 225 is allowed to cool
to a specified temperature range of about 20.degree. C. to
25.degree. C. (about room temperature) to become
temperature-reduced carbonized biomass 226, as discussed above. In
various embodiments, the BPU 202 includes a plurality of cooling
zones. In one embodiment, the cooling zone 216 cools the carbonized
biomass to below 200.degree. C. In one embodiment, the cooling zone
includes a mixer to agitate and uniformly cool the materials. In
various embodiments, one or more of the plurality of cooling zones
is outside of the BPU 202.
[0092] As illustrated in FIGS. 2 and 5, the gas-phase separator
unit 200 includes at least one input and a plurality of outputs. In
this illustrative embodiment, the at least one input is connected
to the exhaust ports on the first/preheat zone 212 and the
second/pyrolysis zone 214 of the BPU 202. One of the outputs is
connected to the carbon recovery unit 500 (which is configured to
enrich the material), and another one of the outputs is connected
to collection equipment or further processing equipment such as an
acid hydrogenation unit 206 or distillation column. In various
embodiments, the gas-phase separator processes the off-gases 220,
222 from the first/preheat zone 212 and the second/pyrolysis zone
214 to produce a condensate 228 and an enrichment gas 204. In one
embodiment, the condensate 228 includes polar compounds, such as
acetic acid, methanol and furfural. In one embodiment, the
enrichment gas 204 produced by the gas-phase separator 200 includes
at least non-polar gases. In one embodiment, the gas-phase
separator comprises a fractionation column. In one embodiment,
acetic acid is sent via a line 228 to an optional acid
hydrogenation unit 206. In another embodiment, methanol and/or
furfural are sent via optional additional line(s) 236 to a
distillation/processing unit 238.
[0093] In the illustrated embodiments, the carbonized biomass exits
the cooling reactor/zone along the material transfer unit 304 and
enters the carbon recovery unit 500. In various embodiments, as
illustrated in more detail in FIG. 5 and discussed above, the
carbon recovery unit 500 also includes an input 524 connected to
the gas-phase separator 200. In one embodiment, the enrichment gas
204 is directed into the carbon recovery unit 500 to be combined
with the biogenic activated carbon product 226 to create a high
carbon biogenic activated carbon product 136. In another
embodiment, a carbon-enriched gas from an external source can also
be directed to the carbon recovery unit 500 to be combined with the
biogenic activated carbon product 226 to add additional carbon to
the biogenic activated carbon product. In various embodiments,
gases pulled from the carbon recovery unit 500 at reference 234 are
optionally used in energy recovery systems and/or systems for
further carbon enrichment. Similarly, in various embodiments, gases
pulled from one or more zones of the BPU 202 are optionally used in
energy recovery systems and/or systems for further carbon
enrichment. Illustratively, the system 200 can be co-located near a
timber processing facility and carbon-enriched gas from the timber
processing facility can be used as gas from an external source.
[0094] Now referring generally to FIG. 3, one material feed system
embodiment of the present disclosure is illustrated. As discussed
above, high oxygen levels in the ambient air surrounding the raw
material as it processes could result in undesirable combustion or
oxidation of the raw material, which reduces the amount and quality
of the final product. In one embodiment, the material feed system
is a closed system and includes one or more manifolds configured to
purge oxygen from the air surrounding the raw material. In one
embodiment, oxygen level of about 0.5% to about 1.0% are used for
pre-heating, pyrolyzing/carbonizing and cooling. It should be
appreciated that a primary goal of the closed material feed system
is to reduce oxygen levels to less than or equal to about 3%, less
than or equal to about 2%, less than or equal to about 1% or less
than or equal to about 0.5%. After the oxygen level is reduced, the
biomass is transferred along the material feed system into the BPU.
It should be appreciated that in various embodiments, pre-heating
of inert gases through recovered process energy and subsequent
introduction of pre-heated inert gases to the BPU, reactor or
trimming reactor makes the system more efficient.
[0095] In some embodiments, a trimming reactor is included in the
system. In one trimming reactor embodiment, pyrolyzed material from
the BPU is fed into a separate additional reactor for further
pyrolysis where heated inert gas is introduced to create a product
with higher fixed carbon levels. In various embodiments, the
secondary process may be conducted in a container such as a drum,
tank, barrel, bin, tote, pipe, sack, press, or roll-off container.
In various embodiments, the final container also may be used for
transport of the carbonized biomass. In some embodiments, the inert
gas is heated via a heat exchanger that derives heat from gases
extracted from the BPU and combusted in a process gas heater.
[0096] As seen in FIG. 3, the closed material feed system 108
includes a raw material feed hopper 300, a material transport unit
304 and an oxygen purge manifold 302.
[0097] In one embodiment, the raw material feed hopper 300 is any
suitable open-air or closed-air container configured to receive raw
or sized/dried biomass 109/209. The raw material feed hopper 300 is
operably connected with the material transport unit 304, which, in
one embodiment, is a screw or auger system operably rotated by a
drive source. In one embodiment, the raw material 109/209 is fed
into the material transport unit 304 by a gravity-feed system. It
should be appreciated that the material transport unit 304 of FIG.
3 is fashioned such that the screw or auger 305 is enclosed in a
suitable enclosure 307. In one embodiment, the enclosure 307 is
substantially cylindrically shaped. In various embodiments,
material feed systems include a screw, auger, conveyor, drum,
screen, chute, drop chamber, pneumatic conveyance device, including
a rotary airlock or a double or triple flap airlock.
[0098] As the raw material 109/209 is fed from the raw material
feed hopper 300 to the material transport unit 304, the auger or
screw 305 is rotated, moving the raw material 109/209 toward the
oxygen purge manifold 302. It should be appreciated that, when the
raw material 109/209 reaches the oxygen purge manifold 302, the
ambient air among the raw material 109/209 in the material
transport unit 304 includes about 20.9% oxygen. In various
embodiments, the oxygen purge manifold 302 is arranged adjacent to
or around the material transport unit 304. Within the oxygen fold
manifold of one embodiment, the enclosure 307 of the material
transport unit 304 includes a plurality of gas inlet ports 310a,
310b, 310c and a plurality of gas outlet ports 308a, 308b,
308c.
[0099] The oxygen purge manifold 302 has at least one gas inlet
line 312 and at least one gas outlet line 314. In various
embodiments, the at least one gas inlet line 312 of the oxygen
purge manifold 302 is in operable communication with each of the
plurality of gas inlet ports 310a, 310b, 310c. Similarly, in
various embodiments, the at least one gas outlet line 314 of the
oxygen purge manifold 302 is in operable communication with each of
the plurality of gas outlet ports 308a, 308b, 308c. It should be
appreciated that, in one embodiment, the gas inlet line 312 is
configured to pump an inert gas into the gas inlet ports 310a,
310b, 310c. In one such embodiment, the inert gas is nitrogen
containing substantially no oxygen. In one embodiment, the inert
gas will flow counter-current to the biomass.
[0100] As will be understood, the introduction of inert gas 312
into the enclosed material transport unit 304 will force the
ambient air out of the enclosed system. In operation, when the
inert gas 312 is introduced to the first gas inlet port 310a of one
embodiment, a quantity of oxygen-rich ambient air is forced out of
outlet port 308a. It should be appreciated that, at this point, the
desired level of less than or equal to about 2% oxygen, less than
or equal to about 1% oxygen, less than or equal to about 0.5%
oxygen or less than or equal to about 0.2% oxygen may not be
achieved. Therefore, in various embodiments, additional infusions
of the inert gas 312 must be made to purge the requisite amount of
oxygen from the air surrounding the raw material 109 in the
enclosed system. In one embodiment, the second gas inlet port 310b
pumps the inert gas 312 into the enclosed system subsequent to the
infusion at the first gas inlet port 310a, thereby purging more of
the remaining oxygen from the enclosed system. It should be
appreciated that, after one or two infusions of inert gas 312 to
purge the oxygen 314, the desired level of less oxygen may be
achieved. If, in one embodiment, the desired oxygen levels are
still not achieved after two inert gas infusions, a third infusion
of inert gas 312 at gas inlet 310c will purge remaining undesired
amounts of oxygen 314 from the enclosed system at gas outlet 308c.
Additional inlets/outlets may also be incorporated if desired. In
various embodiments, oxygen levels are monitored throughout the
material feed system to allow calibration of the amount and
location of inert gas infusions.
[0101] In one alternative embodiment, heat, steam and gases
recovered from the reactor are directed to the feed system where
they are enclosed in jacket and separated from direct contact with
the feed material, but indirectly heat the feed material prior to
introduction to the reactor.
[0102] In one alternative embodiment, heat, steam and gases
recovered from the drying zone of the reactor are directed to the
feed system where they are enclosed in jacket and separated from
direct contact with the feed material, but indirectly heat the feed
material prior to introduction to the reactor.
[0103] It should be appreciated that the gas inlet ports 310a,
310b, 310c and the corresponding gas outlet ports 308a, 308b, 308c,
respectively, of one embodiment are slightly offset from one
another with respect to a vertical bisecting plane through the
material transport unit 304. For example, in one embodiment, inlet
port 310a and corresponding outlet port 308a are offset on material
transport unit 304 by an amount that approximately corresponds with
the pitch of the auger 305 in the material transport unit 304. In
various embodiments, after the atmosphere surrounding the raw
material 109/209 is satisfactorily de-oxygenated, it is fed from
the material feed system 108 into the BPU 102. In various
embodiments, oxygen levels are monitored throughout the material
feed system to allow the calibration of the amount and location of
inert gas infusions.
[0104] It should be appreciated that, in one embodiment, the raw
material 109/209, and subsequently the dried biomass 221, preheated
biomass 123/223, carbonized biomass 125/225 and carbonized biomass
126/226, travel through the reactor 102 (or reactors) along a
continuous material transport unit 304. In another embodiment, the
material transport unit carrying the material differs at different
stages in the process. In one embodiment, the process of moving the
material through the reactor, zones or reactors is continuous. In
one such embodiment, the speed of the material transport unit 304
is appropriately calibrated and calculated by an associated
controller and processor such that the operation of the material
transport unit 304 does not require interruption as the material
moves through the reactor or reactors.
[0105] In another embodiment, the controller associated with the
reactor 102 or reactors (112/114/116) is configured to adjust the
speed of the material transport unit 304 based on one or more
feedback sensors, detected gas (e.g. from the optional FTIR),
measured parameters, temperature gauges, or other suitable
variables in the reactor process. It should be appreciated that, in
various embodiments, any suitable moisture sensors, temperature
sensors or gas sensors in operable communication with the
controller and processor could be integrated into or between each
of the zones/reactors or at any suitable position along the
material transport unit 304. In one embodiment, the controller and
processor use the information from sensors or gauges to optimize
the speed and efficiency of the BPU 100/200. In one embodiment, the
controller associated with the reactor 102 or reactors
(112/114/116) is configured to operate the material transport unit
304. In one embodiment, the controller associated with the reactor
102 or reactors (112/114/116) is configured to monitor the
concentration, temperature and moisture of the gas inside the
material transport unit 304 or inside any of the reactors. In one
embodiment, the controller is configured to adjust the speed of the
material transport unit 304, the input of gases into the material
transport unit and the heat applied to the material in the material
transport unit based upon one or more readings taken by the various
sensors.
[0106] Referring now to FIGS. 2 and 4, one embodiment of the BPU
102 is illustrated. It should be appreciated that the graphical
representation of the BPU 202 in FIG. 4 corresponds substantially
to the BPU 202 in FIG. 2. It should also be appreciated that, in
various embodiments, the BPU 202 is enclosed in a kiln shell to
control and manipulate the high amounts of heat required for the
reactor process. As seen in FIG. 4, in one embodiment, the kiln
shell of the BPU 202 includes several insulating chambers (416,
418) surrounding the four zones 210, 212, 214 and 216. In one
embodiment, the kiln includes four separated zones. In various
embodiments, each of the four zones 210, 212, 214 and 216 of the
BPU 202 includes at least one inlet flight and at least one outlet
flight. As discussed in greater detail below, within each zone of
one such embodiment, the inlet and outlet flights are configured to
be adjustable to control the flow of feed material, gas and heat
into and out of the zone. A supply of inert air can be introduced
into the inlet flight and the purged air can be extracted from the
corresponding outlet flight. In various embodiments, one or more of
the outlet flights of a zone in the BPU 202 are connected to one or
more of the other inlet or outlet flights in the BPU.
[0107] In one embodiment, after the raw material 209 is
de-oxygenated in the material feed system 108, it is introduced to
the BPU 202, and specifically to the first of four zones the
optional drying zone 210. As seen in FIG. 4, the drying zone
includes inlet flight 422b and outlet flight 420a. In one
embodiment, the drying zone is heated to a temperature of about
80.degree. C. to about 150.degree. C. to remove water or other
moisture from the raw materials 209. The biomass is then moved to
the second or pre-heat zone 212 where the biomass is pre-heated as
described above.
[0108] In another embodiment, the material that has optionally been
dried and pre-heated is moved to the third or carbonization zone.
In one embodiment, carbonization occurs at a temperature from about
200.degree. C. to about 700.degree. C., for example about
200.degree. C., about 210.degree. C., about 220.degree. C., about
230.degree. C., about 240.degree. C., about 250.degree. C., about
260.degree. C., about 270.degree. C., about 280.degree. C., about
290.degree. C., about 300.degree. C., about 310.degree. C., about
320.degree. C., about 330.degree. C., about 340.degree. C., about
350.degree. C., about 360.degree. C., about 370.degree. C., about
380.degree. C., about 390.degree. C., about 400.degree. C.,
410.degree. C., about 420.degree. C., about 430.degree. C., about
440.degree. C., about 450.degree. C., about 460.degree. C., about
470.degree. C., about 480.degree. C., about 490.degree. C., about
500.degree. C., about 510.degree. C., about 520.degree. C., about
530.degree. C., about 540.degree. C., about 550.degree. C., about
560.degree. C., about 570.degree. C., about 580.degree. C., about
590.degree. C., about 600.degree. C., about 610.degree. C., about
620.degree. C., about 630.degree. C., about 640.degree. C., about
650.degree. C., about 660.degree. C., about 670.degree. C., about
680.degree. C., about 690.degree. C., or about 700.degree. C. In
another embodiment, a carbonization zone of a reactor 421 is
adapted to allow gases produced during carbonization to be
extracted. In another embodiment, gases produced during
carbonization are extracted for optional later use. In one
embodiment, a carbonization temperature is selected to minimize or
eliminate production of methane (CH.sub.4) and maximize carbon
content of the carbonized biomass.
[0109] In another embodiment, carbonized biomass is moved to a
temperature-reducing or cooling zone (third zone) and is allowed to
passively cool or is actively cooled. In one embodiment, carbonized
biomass solids are cooled to a temperature .+-.10, 20, 30 or
40.degree. C. of room temperature.
[0110] In various embodiments, the BPU includes a plurality of gas
introduction probes and gas extraction probes. In the embodiment of
the BPU illustrated in FIG. 4, the BPU further includes a plurality
of gas introduction probes: 408, 410, 412 and 414, and a plurality
of gas extraction probes: 400, 402, 404 and 406. It should be
appreciated that, in various embodiments, one of each gas
introduction probes and one of each gas extraction probes
correspond with a different one of the plurality of zones 210, 212,
214 and 216. It should also be appreciated that, in various
alternative embodiments, the BPU 202 includes any suitable number
of gas introduction probes and gas extraction probes, including
more than one gas introduction probes and more than one gas
extraction probes for each of the plurality of zones.
[0111] In the illustrated embodiment, the drying zone 210 is
associated with gas introduction probe 412 and gas extraction probe
402. In one embodiment, the gas introduction probe 412 introduces
nitrogen to the drying zone 210 and the gas extraction probe 402
extracts gas from the drying zone 210. It should be appreciated
that, in various embodiments, the gas introduction probe 412 is
configured to introduce a mixture of gas into the drying zone 210.
In one embodiment, the gas extracted is oxygen. It should be
appreciated that, in various embodiments, the gas extraction probe
402 extracts gases from the drying zone 210 to be reused in a heat
or energy recovery system, as described in more detail above.
[0112] In the illustrated embodiment, the pre-heat zone 212 is
associated with gas introduction probe 414 and gas extraction probe
400. In one embodiment, gas introduction probe 414 introduces
nitrogen to the pre-heat zone 212 and gas extraction probe 400
extracts gas from the pre-heat zone 212. It should be appreciated
that, in various embodiments, the gas introduction probe 414 is
configured to introduce a mixture of gas into the pre-heat zone
212. In various embodiments, the gas extracted in gas extraction
probe 400 includes carbon-enriched off-gases. It should be
appreciated that in one embodiment, as discussed above, the gases
extracted from the pre-heat zone 212 and pyrolysis zone 214 are
reintroduced to the material at a later stage in the process, for
example in the carbon recovery unit. In various embodiments, the
gases extracted from any of the zones of the reactor are used for
either energy recovery in the dryer or process gas heater, for
further pyrolysis in a trimming reactor, or in the carbon
enrichment unit.
[0113] In the illustrated embodiment, the pyrolysis zone 214 is
associated with gas introduction probe 410 and gas extraction probe
404. In one embodiment, gas introduction probe 410 introduces
nitrogen to the pyrolysis zone 214 and gas extraction probe 404
extracts gas from the pyrolysis zone 214. It should be appreciated
that, in various embodiments, the gas introduction probe 410 is
configured to introduce a mixture of gas into the pyrolysis zone
214. In various embodiments, the gas extracted in the gas
extraction probe 404 includes carbon-enriched off-gases. It should
be appreciated that in one embodiment, as discussed above, the
carbon-enriched gases extracted from the pyrolysis zone 214 are
used and reintroduced to the material at a later stage in the
process. In various embodiments, as described in more detail below,
the extracted gas 400 from the pre-heat zone 212 and the extracted
gas 404 from the pyrolysis zone 214 are combined prior to being
reintroduced to the material.
[0114] In the illustrated embodiment, the cooling zone 116 is
associated with gas introduction probe 408 and gas extraction probe
406. In one embodiment, gas introduction probe 408 introduces
nitrogen to the cooling zone 116 and gas extraction probe 406
extracts gas from the cooling zone 116. It should be appreciated
that, in various embodiments, the gas introduction probe 408 is
configured to introduce a mixture of gas into the cooling zone 116.
It should be appreciated that, in various embodiments, the gas
extraction probe 406 extracts gases from the cooling zone 116 to be
reused in a heat or energy recovery system, as described in more
detail above.
[0115] It should be appreciated that the gas introduction probes
and gas extraction probes of various embodiments described above
are configured to operate with the controller and plurality of
sensors discussed above to adjust the levels and concentrations of
gas being introduced to and gas being extracted from each zone.
[0116] In various embodiments, the gas introduction probes and gas
extraction probes are made of a suitable pipe configured to
withstand high temperature fluctuations. In one embodiment, the gas
introduction probes and gas extraction probes include a plurality
of openings through which the gas is introduced or extracted. In
various embodiments, the plurality of openings are disposed on the
lower side of the inlet and gas extraction probes. In various
embodiments, each of the plurality of openings extends for a
substantial length within the respective zone.
[0117] In one embodiment, the gas introduction probes extend from
one side of the BPU 202 through each zone. In one such embodiment,
each of the four gas introduction probes extend from a single side
of the BPU to each of the respective zones. In various embodiments,
gaseous catalysts are added that enrich fixed carbon levels. It
should be appreciated that, in such an embodiment, the plurality of
openings for each of the four gas introduction probes are only
disposed in the respective zone associated with that particular gas
introduction probe.
[0118] For example, viewing FIG. 4, if each of the gas introduction
probes extends from the left side of the drying zone into each one
of the zones, all four gas introduction probes would travel through
the drying zone, with the drying zone gas introduction probes
terminating in the drying zone. The three remaining gas
introduction probes would all travel through the pre-heat zone,
with the pre-heat zone gas introduction probe terminating in the
pre-heat zone. The two remaining gas introduction probes would
travel through the pyrolysis zone, with the pyrolysis zone gas
introduction probe terminating in the pyrolysis zone. The cooling
zone gas introduction probe would be the only gas introduction
probe to travel into and terminate in the cooling zone. It should
be appreciated that in various embodiments, the gas extraction
probes are configured similar to the gas introduction probes
described in this example. It should also be appreciated that the
gas introduction probes and gas extraction probes can each start
from either side of the BPU.
[0119] In various embodiments, the gas introduction probes are
arranged concentrically with one another to save space used by the
multiple-port configuration described in the example above. In one
such embodiment, each of the four inlet probes/ports would have a
smaller diameter than the previous inlet probe/port. For example,
in one embodiment, the drying zone gas introduction probe has the
largest interior diameter, and the pre-heat zone gas introduction
probe is situated within the interior diameter of the drying zone
inlet probe/port, the pyrolysis zone gas introduction probe is then
situated within the interior diameter of the pre-heat zone gas
introduction probe and the cooling zone gas introduction probe is
situated within the pyrolysis zone gas introduction probe. In one
example embodiment, a suitable connector is attached to each of the
four gas introduction probes outside of the BPU 102 to control the
air infused into each of the four gas introduction probes
individually.
[0120] In one such embodiment, similar to the example above, the
drying zone gas introduction probe would terminate in the drying
zone, and the three other gas introduction probes would continue
onto the preheat zone. However, with a concentric or substantially
concentric arrangement, only the outer-most gas introduction probe
is exposed in each zone before being terminated. Therefore, in one
such embodiment, the individual zone gas introductions are
effectively controlled independent of one another, while only
requiring one continuous gas introduction probe line. It should be
appreciated that a similar concentric or substantially concentric
configuration is suitably used for the gas extraction probes in one
embodiment.
[0121] In one embodiment, each zone or reactor is adapted to
extract and collect off-gases from one or more of the individual
zones or reactors. In another embodiment, off-gases from each
zone/reactor remain separate for disposal, analysis and/or later
use. In various embodiments, each reactor/zone contains a gas
detection system such as an FTIR that can monitor gas formation
within the zone/reactor. In another embodiment, off-gases from a
plurality of zones/reactors are combined for disposal, analysis
and/or later use, and in various embodiments, off gases from one or
more zones/reactors are fed to a process gas heater. In another
embodiment, off-gases from one or more zones/reactors are fed into
a carbon recovery unit. In another embodiment, off-gases from one
or more zones/reactors are fed to a gas-phase separator prior to
introduction in the carbon recovery unit. In one embodiment, a
gas-phase separator comprises a fractionation column. Any
fractionation column known to those skilled in the art may be used.
In one embodiment, off-gases are separated into non-polar compounds
and polar compounds using a standard fractionation column heated to
a suitable temperature, or a packed column. In another embodiment,
non-polar compounds or enriched gases from a gas-phase separator
are extracted for optional later use, and in various embodiments,
off gases from one or more zones/reactors are fed to a process gas
heater. In one embodiment, gases extracted from the pre-heat
zone/reactor, the pyrolysis zone/reactor and optionally the cooling
zone/reactor are extracted into a combined stream and fed into the
gas-phase separator. In various embodiments, one or more of the
zones/reactors is configured to control whether and how much gas is
introduced into the combined stream.
[0122] As discussed above and generally illustrated in FIG. 5, the
off-gases 124/224 from the BPU 102/202 are directed into the
gas-phase separator 200. In various embodiments, the off-gases
124/224 include the extracted gases 120 from the first/preheat
zone/reactor 112/212 combined with the extracted gases 122/222 from
the second/pyrolysis zone/reactor 114/214 or either gas stream
alone. When the off-gases 124/224 enter the gas-phase separator
200, the off-gases 124/224 are separated into polar compounds
128/228/136/236 and non-polar compounds 204, such as non-polar
gases. In various embodiments, the gas-phase separator 200 is a
known fractionation column.
[0123] In various embodiments, the enriched gases 204 extracted
from the combined off-gases 124/224 are directed from the gas-phase
separator 200 into the carbon recovery unit 500 via input 524,
which enriches the material. As discussed above, and as illustrated
in FIGS. 8 and 11, it should be appreciated that in various
embodiments, the extracted gases are first introduced into a
material enrichment unit, and then into a separate carbon recovery
unit. In the embodiment illustrated in FIG. 5, the material
enrichment takes place in the carbon recovery unit 500. In one
embodiment (FIG. 5), the gas-phase separator 200 includes a
plurality of outputs. In various embodiments, one output from the
gas-phase separator 200 is connected to the carbon recovery unit
500 to introduce an enriched gas stream to the carbon recovery unit
500. In one embodiment, a portion of the enriched gas stream is
directed to the carbon recovery unit 500 and another portion is
directed to a scrubber, or another suitable purifying apparatus to
clean and dispose of unwanted gas. In various embodiments,
off-gases that are not sent to the carbon recovery unit may be used
for either energy recovery (for example in a process gas heater) or
as an inert gas (for example in the deaeration unit, reactor, BPU,
or cooler). Similarly, in various embodiments, off-gases from the
carbon recovery unit may be used for either energy recovery (for
example in a process gas heater), as an inert gas (for example in
the deaeration unit, reactor, BPU, or cooler), or in a secondary
recovery unit.
[0124] In one embodiment, another output from the gas-phase
separator extracts polar compounds, optionally condensing them into
a liquid component, including a plurality of different liquid
parts. In various embodiments, the liquid includes water, acetic
acid, methanol and furfural. In various embodiments, the outputted
liquid is stored, disposed of, further processed, or re-used. For
example, it should be appreciated that the water outputted in one
embodiment can be re-used to heat or cool another portion of a
system. In another embodiment, the water is drained. It should also
be appreciated that the acetic acid, methanol and furfural
outputted in one embodiment can be routed to storage tanks for
re-use, re-sale, distillation or refinement.
[0125] As seen in FIG. 5, the carbon recovery unit 500 of one
embodiment comprises a housing with an upper portion and a lower
portion. It should be appreciated that, in various embodiments in
which a material enrichment unit is separate from the carbon
recovery unit, the material enrichment unit includes features
similar to those discussed with respect to the carbon recovery unit
500 of FIG. 5. In one embodiment, the carbon recovery unit,
comprises: a housing 502 with an upper portion 502a and a lower
portion 502b; an inlet 524 at a bottom of the lower portion of the
housing configured to carry reactor off-gas; an outlet 534 at a top
of the upper portion of the housing configured to carry a
concentrated gas stream; a path 504 defined between the upper
portion and lower portion of the housing; and a transport system
528 following the path, the transport system configured to
transport reagent, wherein the housing is shaped such that the
reagent adsorbs at least some of the reactor off-gas. In various
embodiments, the upper portion includes a plurality of outlets and
the lower portion includes a plurality of inlets.
[0126] In one embodiment, the housing 502 is substantially free of
corners having an angle of 110 degrees or less, 90 degrees or less,
80 degrees or less or 70 degrees or less. In one embodiment, the
housing 502 is substantially free of convex corners. In another
embodiment, the housing 502 is substantially free of convex corners
capable of producing eddies or trapping air. In another embodiment,
the housing 502 is substantially shaped like a cube, rectangular
prism, ellipsoid, a stereographic ellipsoid, a spheroid, two cones
affixed base-to-base, two regular tetrahedrons affixed
base-to-base, two rectangular pyramids affixed base-to-base or two
isosceles triangular prisms affixed base-to-base.
[0127] In one embodiment, the upper portion 502a and lower portion
502b of the housing 502 are each substantially shaped like a
half-ellipsoid, half rectangular prism, half-stereographic
ellipsoid, a half-spheroid, a cone, a regular tetrahedron, a
rectangular pyramid, an isosceles triangular prism or a
round-to-rectangular duct transition.
[0128] In another embodiment, the inlet 524 at the bottom of the
lower portion of the housing 502b and the outlet 534 at the top of
the upper portion of the housing 502a are configured to connect
with a pipe. In another embodiment, the top of the lower portion of
the housing 502b and the bottom of the upper portion of the housing
502a are substantially rectangular, circular or elliptical. In
another embodiment, the width between the top of the lower portion
of the housing 502b and the bottom of the upper portion of the
housing 502a is wider than a width of the transport system 528. In
one embodiment, the width of the transport system 528 is its
height.
[0129] In one embodiment, the carbon recovery unit 500 comprises a
path 504 defined between the upper portion and the lower portion,
an inlet opening 506 and an outlet opening 508. In one embodiment,
the inlet opening and outlet opening are configured to receive the
transport system. In one embodiment, the transport system 528 is at
least semi-permeable or permeable to the enriching gas.
[0130] In one embodiment, the inlet opening 506 includes an inlet
opening sealing mechanism to reduce escape of gas and the outlet
opening 508 includes an outlet opening sealing mechanism to reduce
escape of gas. In one embodiment, the inlet and outlet opening
sealing mechanisms comprise an airlock.
[0131] In various embodiments, the lower portion 502b of the
housing of the carbon recovery unit has a narrow round bottom
connection opening, which is connected to the gas-phase separator
200 for the transport of gas stream 204. In various embodiments,
the top of the lower portion 502b of the housing of the carbon
recovery unit 500 is substantially rectangular in shape, and
substantially wider than the narrow round bottom connection
opening. It should be appreciated that in one embodiment, the lower
portion transitions from the round bottom opening to a rectangular
top opening. In one embodiment, the rectangular top opening of the
lower portion is about six feet wide (along the direction of the
conveyor system). In various embodiments, the top portion of the
carbon recovery unit 500 is shaped substantially similarly to the
lower portion. In one embodiment, the lower opening of the top
portion is wider than the top opening of the lower portion. In one
embodiment, the rectangular lower opening of the top portion is
about six and a half feet wide (along the direction of the conveyor
system). In one embodiment, the top portion is configured to
capture all gases passed through the carbon recovery unit 500 that
are not adsorbed by the activated materials.
[0132] It should be appreciated that, in various embodiments, the
shape of the lower portion of the carbon recovery unit aids in
slowing down and dispersing the gases 204 across a wider surface
area of the conveyor carrying the biogenic activated carbon product
126/226. In various embodiments, the precise shape of the lower
502b and upper 502a portions of the carbon recovery unit 500 depend
upon the angle of gas dispersion coming from the gas-phase
separator pipe. It should be appreciated that in various
embodiments, the gas naturally will tend to expand as it is pumped
up at a flared range of between 5 and 30 degrees from the vertical.
In one embodiment, the flare angle is approximately 15 degrees. It
should be appreciated that the lower portion of the carbon recovery
unit is constructed with as few creases and corners as possible to
prevent the trapping of air or formation of eddies.
[0133] In one embodiment, the carbon recovery unit 500 is
configured to connect to the gas-phase separator 200 as discussed
above, as well as the BPU 102/202. In various embodiments, the
carbon recovery unit 500 is connected to the output of the cooling
reactor/zone 216/116, or the last cooling zone of the BPU 102/202
or outside of the BPU. In one embodiment, the output of the cooling
reactor/zone 116/216 includes biogenic activated carbon product
that have been processed in the BPU 102/202. In one embodiment, the
biogenic activated carbon product 126/226 enters the carbon
recovery unit 500 along a suitable transport system. In various
embodiments, the top portion and the bottom portion of the carbon
recovery unit are connected to one another, and define a pathway
through which a transport system passes. In one embodiment, the
transport system is constructed with a porous or mesh material
configured to allow gas to pass there through. It should be
appreciated that the transport system is configured to pass through
an opening of the carbon recovery unit 500 and then through an exit
opening in the carbon recovery. In some embodiments, the entrance
and the exit into and out of the carbon recovery unit are
appropriately sealed with an airlock or another suitable sealing
mechanism to prevent gases from escaping through the conveyor
opening. In various embodiments, off-gases that are not sent to the
carbon recovery unit may be used for either energy recovery (for
example in a process gas heater) or as an inert gas (for example in
the deaeration unit, reactor, BPU, or cooler). Similarly, in
various embodiments, off-gases from the carbon recovery unit may be
used for either energy recovery (for example in a process gas
heater), as an inert gas (for example in the deaeration unit,
reactor, BPU, or cooler), or in a secondary recovery unit.
[0134] In various embodiments, the process operates by first
outputting the biogenic activated carbon product 126/226 from the
cooling zone 116/216 onto the transport system using a suitable
discharge mechanism from the cooling reactor/zone 116/216. In one
embodiment, the biogenic activated carbon product 126/216 are
spread across the width of the transport system to minimize
material stacking or bunching and maximize surface area for gaseous
absorption. At the point which the biogenic activated carbon
product 126/216 are deposited and suitably spread onto the
transport system, in various embodiments, the transport system
transports the biogenic activated carbon product 126/216 through
the opening in the carbon recovery unit 104 defined between the
lower portion and the top portion discussed above. In the carbon
recovery unit 104, the biogenic activated carbon product 126/216
adsorb gases piped into the lower portion of the carbon recovery
unit 104 from the gas-phase separator 200. After the biogenic
activated carbon product is enriched with non-polar gases, it
should be appreciated that the biogenic activated carbon product
becomes a high carbon biogenic activated carbon product. In various
embodiments, the high carbon biogenic activated carbon product is a
final product of the process disclosed herein and is transported
away from the carbon recovery unit 104 into a suitable storage or
post-processing apparatus.
[0135] In one embodiment, after the enriched gases 204 pass through
the conveyor and the biogenic activated carbon product 126/216, the
resulting gas is extracted at the top portion of the carbon
recovery unit 104. In various embodiments, the exhausted gases 134
are carried away to a suitable scrubber, stack or recovery system.
In some embodiments, the exhaust gases are exploited for any
reusable qualities in the system, including usage in a secondary
carbon recovery unit or for energy. In various embodiments,
off-gases that are not sent to the carbon recovery unit may be used
for either energy recovery (for example in a process gas heater) or
as an inert gas (for example in the deaeration unit, reactor, BPU,
or cooler). Similarly, in various embodiments, off-gases from the
carbon recovery unit may be used for either energy recovery (for
example in a process gas heater), as an inert gas (for example in
the deaeration unit, reactor, BPU, or cooler), or in a secondary
recovery unit.
[0136] It should be appreciated that the biogenic activated carbon
product 126/216 include a high amount of carbon, and carbon has a
high preference for adsorbing non-polar gases. It should also be
appreciated that the enriched gas stream 204 includes primarily
non-polar gases like terpenes, carbon monoxide, carbon dioxide and
methane. In various embodiments, as the enriched gases are directed
from the gas-phase separator into the carbon recovery unit, the gas
flow rate and the conveyor speed are monitored and controlled to
ensure maximum absorption of the non-polar gases in the biogenic
activated carbon product 126/216. In another embodiment, the
high-energy organic compounds comprise at least a portion of the
enriched gases 204 eluted during carbonization of the biomass, and
outputted from the gas-phase separator 200 to the carbon recovery
unit 104. In various embodiments, the enriched gases 204 are
further enriched with additional additives prior to being
introduced to the carbon recovery unit or material enrichment
unit.
[0137] As discussed in more detail below, in various embodiments,
the residence time of the biogenic activated carbon product 126/216
in the carbon recovery unit is controlled and varies based upon the
composition of the biogenic activated carbon product 126/216 and
gas flow and composition. In one embodiment, the biogenic activated
carbon product is passed through one or more carbon recovery units
more than one time. In various embodiments, the output of enriched
air from the gas-phase separator and the output of exhausted air
from the carbon recovery unit 104 can be diverted or bifurcated
into an additional carbon recovery unit or further refined or used
for energy or inert gas for use in the process.
[0138] Referring more generally to FIGS. 6 to 13, various
embodiments of the present disclosure are illustrated and
discussed. It should be appreciated that the various embodiments
and alternatives discussed below with respect to FIGS. 6 to 13
apply to the embodiments of FIGS. 1 to 5 discussed above, and vice
versa.
[0139] Referring specifically now to FIG. 6, this embodiment can
utilize a BPU including a single reactor having two to a greater
plurality of different zones. Two zones are shown in the
illustrative embodiment, however, any different number of zones
could be employed. In one embodiment, each zone is connected to at
least one other zone via a material transport unit (not pictured).
In one embodiment, the material transport unit controls atmosphere
and temperature conditions.
[0140] Specifically in one embodiment illustrated in FIG. 6, the
system 600 includes a material feed system 602, a BPU 606 including
a pyrolysis zone 608 and a cooling zone 610, a cooler 614 and a
carbon recovery unit 616. It should be appreciated that the cooler
614 of FIG. 6 is outside of the BPU 606, and is in addition to the
cooling zone 610 that resides within the BPU 606.
[0141] In various embodiments, the system 600 includes an optional
dryer between the material feed system 602 and the BPU 606. In
various embodiments, the BPU 606 includes a plurality of zones. In
FIG. 6, the BPU 606 includes a pyrolysis zone 608 and a cooling
zone 610. The BPU 606 also includes at least a plurality of inlets
and outlets for adding substances to and removing various
substances from the plurality of zone 608, 610, including at least
condensable vapors and non-condensable gases 612. It should be
appreciated that in various embodiments discussed below, one or
more of the plurality of zone 608 or 610 are enclosed by the BPU
606.
[0142] Referring now to FIG. 7, a system 700 of one embodiment is
illustrated and discussed. System 700 includes a single-reactor
system, including a material feed system 702, a pre-heater 706, a
pyrolysis reactor 708, a cooler, 714 and a carbon recovery unit
716. In various embodiments, the system 700 includes an optional
dryer 704 between the material feed system 702 and the pre-heater
706. As seen in FIG. 7, the pyrolysis reactor 708 of one embodiment
includes at least one gas inlet 710 and at least one outlet 712 for
outputting substances from the pyrolysis reactor 708. In various
embodiments, the substances outputted through outlet 712 include
condensable vapors and/or non-condensable gases. It should be
appreciated that the pyrolysis reactor 708 can include one or more
zones, not discussed in detail herein. In various embodiments, the
system 700 includes one or more reactors in addition to the
pyrolysis reactor 708.
[0143] Referring now to FIG. 8, a single-reactor, multiple zone BPU
system 800 of one embodiment is illustrated and discussed. System
800 includes a material feed system 802, a BPU 808 having a
pyrolysis zone 810 and a cooling zone 812, a material enrichment
unit 818, and a carbon recovery unit 820. Similar to the
embodiments discussed above, FIG. 8 also includes an optional dryer
804 located between the material feed system 802 and the BPU 808.
It should be appreciated that moisture 806 from the dryer 804 is
removed during the drying process. FIG. 8 also includes an optional
cooler 816 outside of the BPU 808 and before the material
enrichment unit 818. As discussed in more detail below, the
material enrichment unit 818 is in communication with a gas outlet
814 of the BPU 808, which carries condensable vapors and
non-condensable gases from the BPU. It should be appreciated that
various embodiments illustrated in FIG. 8 include a separate carbon
recovery unit 820 from the material enrichment unit 818. As
discussed above, in various embodiments, the carbon recovery unit
820 of FIG. 8 is an appropriate vessel in which the enriched
material is stored following the material enrichment unit 818, and
the carbon recovery unit 820 does not further enrich the
material.
[0144] It should be appreciated that, in various embodiments, an
optional process gas heater 824 is disposed in the system and
attached to the BPU 808. In various embodiments, vapors or other
off-gases from the BPU 808 are inputted into the optional process
gas heater 824, along with an external source of any one or more of
air, natural gas, and nitrogen. As discussed below, in various
embodiments, the air emissions from the process gas heater 824 are
inputted into dryer 804 as a heat or energy recovery system.
[0145] Referring now to FIG. 9, a BPU 908 of a system 900 of one
embodiment is illustrated and discussed. The BPU 908 includes a
plurality of zones: the pre-heat zone 904, the pyrolysis zone 910,
and the cooling zone 914. The BPU 908 of one embodiment also
includes a material feed system 902 in communication with one of
the zones at least one gas inlet 906 in communication with one or
more of the zones 904, 910, 914. In various embodiments, as
discussed below, one of the zones also includes at least one outlet
912 for outputting substances, in one embodiment, condensable
vapors and/or non-condensable gases. In various embodiments, one of
the zones also includes an outlet for outputting the advanced
carbon from the system 900.
[0146] It should be appreciated that, although FIG. 9 shows the gas
inlet 906 being connected to the pre-heat zone 904, various
embodiments include inlets into any combination of the three zones.
Similarly, it should be appreciated that although the gaseous
outlet 912 comes from the pyrolysis zone 910, various embodiments
include outlets out of one or more of any combination of the three
zones. As discussed below, various embodiments contemplated include
inputs and outputs within the BPU: e.g., an outlet of the pyrolysis
zone 910 is then input into the pre-heat zone 904. It should be
appreciated that, in the illustrated embodiment, each of the
reactors in the BPU is connected to one another via the material
feed system, as discussed above.
[0147] In various embodiments, the pre-heat zone 904 of the BPU 908
is configured for feeding biomass 902 (or another carbon-containing
feedstock) in a manner that does not "shock" the biomass, which
would rupture the cell walls and initiate fast decomposition of the
solid phase into vapors and gases. In one embodiment, pre-heat zone
904 can be thought of as mild pyrolysis.
[0148] In various embodiments, pyrolysis zone 910 of the BPU 908 is
configured as the primary reaction zone, in which preheated
material undergoes pyrolysis chemistry to release gases and
condensable vapors, resulting in a solid material which is a
high-carbon reaction intermediate. Biomass components (primarily
cellulose, hemicellulose, and lignin) decompose and create vapors,
which escape by penetrating through pores or creating new
nanopores. The latter effect contributes to the creation of
porosity and surface area.
[0149] In various embodiments, the cooling zone 914 of the BPU 908
is configured for receiving the high-carbon reaction intermediate
and cooling down the solids, i.e. the cooling zone 914 will be a
lower temperature than the pyrolysis zone 910. In the cooling zone
914, the chemistry and mass transport can be complex. In various
embodiments, secondary reactions occur in the cooling zone 914. It
should be appreciated that carbon-containing components that are in
the gas phase can decompose to form additional fixed carbon and/or
become adsorbed onto the carbon. Thus, the advanced carbon 916 is
not simply the solid, devolatilized residue of the processing
steps, but rather includes additional carbon that has been
deposited from the gas phase, such as by decomposition of organic
vapors (e.g., tars) that can form carbon.
[0150] Referring now to FIGS. 10 to 13, various multiple reactor
embodiments of the system are illustrated and discussed. Similar to
each of the embodiments, the systems include an optional deaerator
and an optional dryer, as discussed in more detail below. Referring
to FIG. 10, the system 1000 includes material feed system 1002, a
pyrolysis reactor 1012, a cooling reactor 1018, a cooler 1020 and a
carbon recovery unit 1022. As discussed further below, a gas source
1016 is configured to input gas into one or both of the pyrolysis
reactor 1012 and the cooling reactor 1018. In various embodiments,
the pyrolysis reactor includes an outlet to output at least
condensable vapors and/or non-condensable gases. In various
embodiments, the carbon recovery unit 1022 includes an outlet 1024
to output activated carbon from the system 1000.
[0151] It should be appreciated that, in various embodiments
illustrated at least in FIGS. 10 to 13, the illustrated systems
includes an optional de-aerator and an optional dryer. As seen in
FIG. 10, for example, represented by broken lines, the optional
de-aerator 1004 is connected to the system 1000 between the
material feed system 1002 and the pyrolysis reactor 1002.
Similarly, the dryer 1006 is connected to the system 1000 between
the material feed system 1002 and the pyrolysis reactor 1012. In
various embodiments, the dryer 1006 and deaerator 1004 are also
connected to one another such that the material from the material
feed system can follow any number of different paths through the
material feed system, the de-aerator, the dryer, and to the
pyrolysis reactor. It should be appreciated that in some
embodiments, the material only passes through one of the optional
de-aerator 1004 and dryer 1006.
[0152] In some embodiments, with reference to FIG. 10, a process
for producing a biogenic activated carbon comprises the following
steps: [0153] (a) providing a carbon-containing feedstock
comprising biomass; [0154] (b) optionally drying the feedstock to
remove at least a portion of moisture contained within the
feedstock; [0155] (c) optionally deaerating the feedstock to remove
at least a portion of interstitial oxygen, if any, contained with
the feedstock; [0156] (d) pyrolyzing the feedstock in the presence
of a substantially inert gas phase for at least 10 minutes and with
at least one temperature selected from about 250.degree. C. to
about 700.degree. C., to generate hot pyrolyzed solids, condensable
vapors, and non-condensable gases; [0157] (e) separating at least a
portion of the condensable vapors and at least a portion of the
non-condensable gases from the hot pyrolyzed solids; [0158] (f)
cooling the hot pyrolyzed solids to generate cooled pyrolyzed
solids; and [0159] (g) recovering a biogenic activated carbon
comprising at least a portion of the cooled pyrolyzed solids.
[0160] Referring now to FIG. 11 a multiple reactor system 1100 of
one embodiment is illustrated. Similar to the embodiment discussed
above and illustrated in FIG. 10, this embodiment includes a
material feed system 1102, pyrolysis reactor 1112, cooling reactor
1118, and carbon recovery unit 1124. In the illustrated embodiment
of FIG. 11, the cooler 1120 is optional, and a material enrichment
unit 1122 is disposed between the optional cooler 1120 and the
carbon recovery unit 1124. It should be appreciated that, in
various embodiments, the material enrichment unit 1122 enriches the
material before it continues into the separate carbon recovery unit
1124, which may or may not further enrich the material. In various
embodiments, an optional deaerator 1104 and an optional dryer 1106
are disposed between the material feed system 1102 and the
pyrolysis reactor 1112. In the illustrated embodiment, the
pyrolysis reactor 1112 also includes an outlet 1114 configured to
remove substances such as condensable vapors and non-condensable
gases, and route the removed substances to the material enrichment
unit 1122.
[0161] Various embodiments extend the concept of additional carbon
formation by including a separate material enrichment unit 818,
1122 in which cooled carbon is subjected to an environment
including carbon-containing species, to enrich the carbon content
of the final product. When the temperature of this unit is below
pyrolysis temperatures, the additional carbon is expected to be in
the form of adsorbed carbonaceous species, rather than additional
fixed carbon.
[0162] As will be described in detail below, there are a large
number of options as to intermediate input and output (purge or
probe) streams of one or more phases present in any particular
reactor, various mass and energy recycle schemes, various additives
that may be introduced anywhere in the process, adjustability of
process conditions including both reaction and separation
conditions in order to tailor product distributions, and so on.
Zone or reactor-specific input and output streams enable good
process monitoring and control, such as through FTIR sampling and
dynamic process adjustments.
[0163] The present disclosure is different than fast pyrolysis, and
it is different than conventional slow pyrolysis. High-quality
carbon materials in the present disclosure, including compositions
with high fractions of fixed carbon, may be obtained from the
disclosed processes and systems.
[0164] "Biomass," for purposes of this disclosure, shall be
construed as any biogenic feedstock or mixture of a biogenic and
non-biogenic feedstock. Elementally, biomass includes at least
carbon, hydrogen, and oxygen. The methods and apparatus of the
disclosure can accommodate a wide range of feedstocks of various
types, sizes, and moisture contents.
[0165] Biomass includes, for example, plant and plant-derived
material, vegetation, agricultural waste, forestry waste, wood
waste, paper waste, animal-derived waste, poultry-derived waste,
and municipal solid waste. In various embodiments of the disclosure
utilizing biomass, the biomass feedstock may include one or more
materials selected from: timber harvesting residues, softwood
chips, hardwood chips, tree branches, tree stumps, knots, leaves,
bark, sawdust, off-spec paper pulp, cellulose, corn, corn stover,
wheat straw, rice straw, sugarcane bagasse, switchgrass,
miscanthus, animal manure, municipal garbage, municipal sewage,
commercial waste, grape pumice, almond shells, pecan shells,
coconut shells, coffee grounds, grass pellets, hay pellets, wood
pellets, cardboard, paper, carbohydrates, plastic, and cloth. A
person of ordinary skill in the art will readily appreciate that
the feedstock options are virtually unlimited.
[0166] Various embodiments of the present disclosure are also be
used for carbon-containing feedstocks other than biomass, such as a
fossil fuel (e.g., coal or petroleum coke), or any mixtures of
biomass and fossil fuels (such as biomass/coal blends). In some
embodiments, a biogenic feedstock is, or includes, coal, oil shale,
crude oil, asphalt, or solids from crude-oil processing (such as
petcoke). Feedstocks may include waste tires, recycled plastics,
recycled paper, and other waste or recycled materials. Any method,
apparatus, or system described herein may be used with any
carbonaceous feedstock. Carbon-containing feedstocks may be
transportable by any known means, such as by truck, train, ship,
barge, tractor trailer, or any other vehicle or means of
conveyance.
[0167] Selection of a particular feedstock or feedstocks is not
regarded as technically critical, but is carried out in a manner
that tends to favor an economical process. Typically, regardless of
the feedstocks chosen, there can be (in some embodiments) screening
to remove undesirable materials. The feedstock can optionally be
dried prior to processing.
[0168] The feedstock employed may be provided or processed into a
wide variety of particle sizes or shapes. For example, the feed
material may be a fine powder, or a mixture of fine and coarse
particles. The feed material may be in the form of large pieces of
material, such as wood chips or other forms of wood (e.g., round,
cylindrical, square, etc.). In some embodiments, the feed material
comprises pellets or other agglomerated forms of particles that
have been pressed together or otherwise bound, such as with a
binder.
[0169] It is noted that size reduction is a costly and
energy-intensive process. Pyrolyzed material can be sized with
significantly less energy input, i.e. it can be more energy
efficient to reduce the particle size of the product, not the
feedstock. This is an option in the present disclosure because the
process does not require a fine starting material, and there is not
necessarily any particle-size reduction during processing. The
present disclosure provides the ability to process very large
pieces of feedstock. Notably, some market applications of the
activated carbon product actually require large sizes (e.g., on the
order of centimeters), so that in some embodiments, large pieces
are fed, produced, and sold. It should be appreciated that, while
not necessary in all embodiments of this disclosure, smaller sizing
has resulted in higher fixed carbon numbers under similar process
conditions and may be utilized in some applications that typically
call for small sized activated carbon products and/or higher fixed
carbon content.
[0170] When it is desired to produce a final carbonaceous biogenic
activated carbon product that has structural integrity, such as in
the form of cylinders, there are at least two options in the
context of this disclosure. First, the material produced from the
process is collected and then further process mechanically into the
desired form. For example, the product is pressed or pelletized,
with a binder. The second option is to utilize feed materials that
generally possess the desired size and/or shape for the final
product, and employ processing steps that do not destroy the basic
structure of the feed material. In some embodiments, the feed and
product have similar geometrical shapes, such as spheres,
cylinders, or cubes.
[0171] The ability to maintain the approximate shape of feed
material throughout the process is beneficial when product strength
is important. Also, this control avoids the difficulty and cost of
pelletizing high fixed-carbon materials.
[0172] The starting feed material in various embodiments is
provided with a range of moisture levels, as will be appreciated.
In some embodiments, the feed material is already sufficiently dry
that it need not be further dried before pyrolysis. Typically, it
will be desirable to utilize commercial sources of biomass which
will usually contain moisture, and feed the biomass through a
drying step before introduction into the pyrolysis reactor.
However, in some embodiments a dried feedstock is used. It should
be appreciated that, in various embodiments, while any biomass
works, the following factors may impact the process and its
products: how material is grown, harvested, irrigated, material
species selection and carbon content. Particularly, in various
embodiments, low fertilizer and low phosphorous used in growing
results in better properties for metal making. In various
embodiments, low impact shearing during harvest results in greater
strength. In various embodiments, less irrigation and smaller
growth rings may result in greater strength.
[0173] It should be appreciated that, in various embodiments
additives and/or catalysts are included in the BPU, and temperature
profiles within the BPU are selected to promote production of
carbon dioxide over carbon monoxide, leading to greater fixed
carbon in the final product.
[0174] It is desirable to provide a relatively low-oxygen
environment in the pyrolysis reactor, such as about 10%, 5%, 3%, or
1% O.sub.2 in the gas phase. First, uncontrolled combustion should
be avoided in the pyrolysis reactor, for safety reasons. Some
amount of total carbon oxidation to CO.sub.2 may occur, and the
heat released from the exothermic oxidation may assist the
endothermic pyrolysis chemistry. Large amounts of oxidation of
carbon, including partial oxidation to syngas, will reduce the
carbon yield to solids.
[0175] Practically speaking, it can be difficult to achieve a
strictly oxygen-free environment in each of the reactor(s) or the
BPU. This limit can be approached, and in some embodiments, the
reactor(s) or the BPU is substantially free of molecular oxygen in
the gas phase. To ensure that little or no oxygen is present in the
reactor(s) or BPU, it may be desirable to remove air from the feed
material before it is introduced to the reactor(s) or the BPU.
There are various ways to remove or reduce air in the
feedstock.
[0176] In some embodiments, as seen in FIGS. 10, 11, 12 and 13, a
deaeration unit is utilized in which feedstock, before or after
drying, is conveyed in the presence of another gas which can remove
adsorbed oxygen and penetrate the feedstock pores to remove oxygen
from the pores. Most gases that have lower than 21 vol % O.sub.2
may be employed, at varying effectiveness. In some embodiments,
nitrogen is employed. In some embodiments, CO and/or CO.sub.2 is
employed. Mixtures may be used, such as a mixture of nitrogen and a
small amount of oxygen. Steam may be present in the deaeration gas,
although adding significant moisture back to the feed should be
avoided. The effluent from the deaeration unit may be purged (to
the atmosphere or to an emissions treatment unit) or recycled.
[0177] In principle, the effluent (or a portion thereof) from the
deaeration unit could be introduced into the pyrolysis reactor
itself since the oxygen removed from the solids will now be highly
diluted. In this embodiment, it may be advantageous to introduce
the deaeration effluent gas to the last zone of the reactor, when
it is operated in a countercurrent configuration.
[0178] Various types of deaeration units may be employed. In one
embodiment, if drying it to be performed, deaerating after drying
prevents the step of scrubbing soluble oxygen out of the moisture
present. In certain embodiments, the drying and deaerating steps
are combined into a single unit, or some amount of deaeration is
achieved during drying.
[0179] The optionally dried and optionally deaerated feed material
is introduced to a pyrolysis reactor or multiple reactors in series
or parallel. The material feed system in various embodiments
introduces the feedstock using any known means, including screw
material feed systems or lock hoppers, for example. In some
embodiments, a material feed system incorporates an airlock.
[0180] When a single reactor is employed (such as in FIG. 6, 3 or
4), multiple zones can be present. Multiple zones, such as two,
three, four, or more zones, can allow for the separate control of
temperature, solids residence time, gas residence time, gas
composition, flow pattern, and/or pressure in order to adjust the
overall process performance.
[0181] As discussed above, references to "zones" shall be broadly
construed to include regions of space within a single physical unit
(such as in FIG. 6, 8 or 9), physically separate units (such as in
FIGS. 7 and 10 to 13), or any combination thereof. For a BPU, the
demarcation of zones within that BPU may relate to structure, such
as the presence of flights within the BPU or distinct heating
elements to provide heat to separate zones. Alternatively, or
additionally, in various embodiments, the demarcation of zones in a
BPU relates to function, such as at least: distinct temperatures,
fluid flow patterns, solid flow patterns, and extent of reaction.
In a single batch reactor, "zones" are operating regimes in time,
rather than in space. Various embodiments include the use of
multiple batch BPUs.
[0182] It will be appreciated that there are not necessarily abrupt
transitions from one zone to another zone. For example, the
boundary between the preheating zone and pyrolysis zone may be
somewhat arbitrary; some amount of pyrolysis may take place in a
portion of the preheating zone, and some amount of "preheating" may
continue to take place in the pyrolysis zone. The temperature
profile in the BPU is typically continuous, including at zone
boundaries within the zone.
[0183] Some embodiments, as seen for example in FIG. 9, employ a
pre-heat zone 304 that is operated under conditions of preheating
and/or mild pyrolysis. In various embodiments, the temperature of
the pre-heat zone 304 is from about 80.degree. C. to about
500.degree. C., such as about 300.degree. C. to about 400.degree.
C. In various embodiments, the temperature of the pre-heat zone 304
is not so high as to shock the biomass material which ruptures the
cell walls and initiates fast decomposition of the solid phase into
vapors and gases. Pyrolysis commonly known as fast or flash
pyrolysis is avoided in the present disclosure.
[0184] All references to zone temperatures in this specification
should be construed in a non-limiting way to include temperatures
that may apply to the bulk solids present, or the gas phase, or the
reactor or BPU walls (on the process side). It will be understood
that there will be a temperature gradient in each zone, both
axially and radially, as well as temporally (i.e., following
start-up or due to transients). Thus, references to zone
temperatures may be references to average temperatures or other
effective temperatures that may influence the actual kinetics.
Temperatures may be directly measured by thermocouples or other
temperature probes, or indirectly measured or estimated by other
means.
[0185] The second zone, or the primary pyrolysis zone, is operated
under conditions of pyrolysis or carbonization. The temperature of
the pyrolysis zone may be selected from about 250.degree. C. to
about 700.degree. C., such as about 300.degree. C., 350.degree. C.,
400.degree. C., 450.degree. C., 500.degree. C., 550.degree. C.,
600.degree. C., or 650.degree. C. Within this zone, preheated
biomass undergoes pyrolysis chemistry to release gases and
condensable vapors, leaving a significant amount of solid material
as a high-carbon reaction intermediate. Biomass components
(primarily cellulose, hemicellulose, and lignin) decompose and
create vapors, which escape by penetrating through pores or
creating new pores. The temperature will at least depend on the
residence time of the pyrolysis zone, as well as the nature of the
feedstock and product properties.
[0186] The cooling zone is operated to cool down the high-carbon
reaction intermediate to varying degrees. In various embodiments,
the temperature of the cooling zone is a lower temperature than
that of the pyrolysis zone. In various embodiments, the temperature
of the cooling zone is selected from about 100.degree. C. to about
550.degree. C., such as about 150.degree. C. to about 350.degree.
C.
[0187] In various embodiments, chemical reactions continue to occur
in the cooling zone. It should be appreciated that in various
embodiments, secondary pyrolysis reactions are initiated in the
cooling zone. Carbon-containing components that are in the gas
phase can condense (due to the reduced temperature of the cooling
zone). The temperature remains sufficiently high, however, to
promote reactions that may form additional fixed carbon from the
condensed liquids (secondary pyrolysis) or at least form bonds
between adsorbed species and the fixed carbon. One exemplary
reaction that may take place is the conversion of carbon monoxide
to carbon dioxide plus fixed carbon (Boudouard reaction).
[0188] The residence times of the zones may vary. For a desired
amount of pyrolysis, higher temperatures may allow for lower
reaction times, and vice versa. The residence time in a continuous
BPU (reactor) is the volume divided by the volumetric flow rate.
The residence time in a batch reactor is the batch reaction time,
following heating to reaction temperature.
[0189] It should be recognized that in multiphase BPUs, there are
multiple residence times. In the present context, in each zone,
there will be a residence time (and residence-time distribution) of
both the solids phase and the vapor phase. For a given apparatus
employing multiple zones, and with a given throughput, the
residence times across the zones will generally be coupled on the
solids side, but residence times may be uncoupled on the vapor side
when multiple inlet and outlet ports are utilized in individual
zones. in various embodiments, the solids and vapor residence times
are uncoupled.
[0190] The solids residence time of the preheating zone may be
selected from about 5 min to about 60 min, such as about 10 min
depending on the temperature and time required to reach a preheat
temperature. The heat-transfer rate, which will depend on the
particle type and size, the physical apparatus, and on the heating
parameters, will dictate the minimum residence time necessary to
allow the solids to reach a predetermined preheat temperature.
[0191] The solids residence time of the pyrolysis zone may be
selected from about 10 min to about 120 min, such as about 20 min,
30 min, or 45 min. Depending on the pyrolysis temperature in this
zone, there should be sufficient time to allow the carbonization
chemistry to take place, following the necessary heat transfer. For
times below about 10 min, in order to remove high quantities of
non-carbon elements, the temperature would need to be quite high,
such as above 700.degree. C. This temperature would promote fast
pyrolysis and its generation of vapors and gases derived from the
carbon itself, which is to be avoided when the intended product is
solid carbon.
[0192] In a static system of various embodiments, an equilibrium
conversion is reached at a certain time. When, as in certain
embodiments, vapor is continuously flowing over solids with
continuous volatiles removal, the equilibrium constraint may be
removed to allow for pyrolysis and devolatilization to continue
until reaction rates approach zero. Longer times would not tend to
substantially alter the remaining recalcitrant solids.
[0193] The solids residence time of the cooling zone in various
embodiments may be selected from about 5 min to about 60 min, such
as about 30 min. Depending on the cooling temperature in this zone,
there should be sufficient time to allow the carbon solids to cool
to the desired temperature. The cooling rate and temperature will
dictate the minimum residence time necessary to allow the carbon to
be cooled. Additional time may not be desirable, unless some amount
of secondary pyrolysis is desired.
[0194] As discussed above, the residence time of the vapor phase
may be separately selected and controlled. The vapor residence time
of the preheating zone may be selected from about 0.1 min to about
10 min, such as about 1 min. The vapor residence time of the
pyrolysis zone may be selected from about 0.1 min to about 20 min,
such as about 2 min. The vapor residence time of the cooling zone
may be selected from about 0.1 min to about 15 min, such as about
1.5 min. Short vapor residence times promote fast sweeping of
volatiles out of the system, while longer vapor residence times
promote reactions of components in the vapor phase with the solid
phase.
[0195] The mode of operation for the reactor, and overall system,
may be continuous, semi-continuous, batch, or any combination or
variation of these. In some embodiments, the BPU is a continuous,
countercurrent reactor in which solids and vapor flow substantially
in opposite directions. The BPU may also be operated in batch but
with simulated countercurrent flow of vapors, such as by
periodically introducing and removing gas phases from the batch
vessel.
[0196] Various flow patterns may be desired or observed. With
chemical reactions and simultaneous separations involving multiple
phases in multiple zones, the fluid dynamics can be quite complex.
Typically, the flow of solids may approach plug flow (well-mixed in
the radial dimension) while the flow of vapor may approach fully
mixed flow (fast transport in both radial and axial dimensions).
Multiple inlet and outlet ports for vapor may contribute to overall
mixing.
[0197] The pressure in each zone may be separately selected and
controlled. The pressure of each zone may be independently selected
from about 1 kPa to about 3000 kPa, such as about 101.3 kPa (normal
atmospheric pressure). Independent zone control of pressure is
possible when multiple gas inlets and outlets are used, including
vacuum ports to withdraw gas when a zone pressure less than or
equal to about atmospheric is desired. Similarly, in a multiple
reactor system, the pressure in each reactor may be independently
selected and controlled.
[0198] The process may conveniently be operated at atmospheric
pressure, in some embodiments. There are many advantages associated
with operation at atmospheric pressure, ranging from mechanical
simplicity to enhanced safety. In certain embodiments, the
pyrolysis zone is operated at a pressure of about 90 kPa, 95 kPa,
100 kPa, 101 kPa, 102 kPa, 105 kPa, or 110 kPa (absolute
pressures).
[0199] Vacuum operation (e.g., 10-100 kPa) would promote fast
sweeping of volatiles out of the system. Higher pressures (e.g.,
100-1000 kPa) may be useful when the off-gases will be fed to a
high-pressure operation. Elevated pressures may also be useful to
promote heat transfer, chemistry, or separations.
[0200] The step of separating at least a portion of the condensable
vapors and at least a portion of the non-condensable gases from the
hot pyrolyzed solids may be accomplished in the reactor itself, or
using a distinct separation unit. A substantially inert sweep gas
may be introduced into one or more of the zones. Condensable vapors
and non-condensable gases are then carried away from the zone (s)
in the sweep gas, and out of the BPU.
[0201] The sweep gas may be N.sub.2, Ar, CO, CO.sub.2, H.sub.2,
H.sub.2O, CH.sub.4, other light hydrocarbons, or combinations
thereof, for example. The sweep gas may first be preheated prior to
introduction, or possibly cooled if it is obtained from a heated
source.
[0202] The sweep gas more thoroughly removes volatile components,
by getting them out of the system before they can condense or
further react. The sweep gas allows volatiles to be removed at
higher rates than would be attained merely from volatilization at a
given process temperature. Or, use of the sweep gas allows milder
temperatures to be used to remove a certain quantity of volatiles.
The reason the sweep gas improves the volatiles removal is that the
mechanism of separation is not merely relative volatility but
rather liquid/vapor phase disengagement assisted by the sweep gas.
The sweep gas can both reduce mass-transfer limitations of
volatilization as well as reduce thermodynamic limitations by
continuously depleting a given volatile species, to cause more of
it to vaporize to attain thermodynamic equilibrium.
[0203] It is important to remove gases laden with volatile organic
carbon from subsequent processing stages, in order to produce a
product with high fixed carbon. Without removal, the volatile
carbon can adsorb or absorb onto the pyrolyzed solids, thereby
requiring additional energy (cost) to achieve a purer form of
carbon which may be desired. By removing vapors quickly, it is also
speculated that porosity may be enhanced in the pyrolyzing solids.
In various embodiments, such as activated carbon products, higher
porosity is desirable.
[0204] In certain embodiments, the sweep gas in conjunction with a
relatively low process pressure, such as atmospheric pressure,
provides for fast vapor removal without large amounts of inert gas
necessary.
[0205] In some embodiments, the sweep gas flows countercurrent to
the flow direction of feedstock. In other embodiments, the sweep
gas flows cocurrent to the flow direction of feedstock. In some
embodiments, the flow pattern of solids approaches plug flow while
the flow pattern of the sweep gas, and gas phase generally,
approaches fully mixed flow in one or more zones.
[0206] The sweep may be performed in any one or more of the zones.
In some embodiments, the sweep gas is introduced into the cooling
zone and extracted (along with volatiles produced) from the cooling
and/or pyrolysis zones. In some embodiments, the sweep gas is
introduced into the pyrolysis zone and extracted from the pyrolysis
and/or preheating zones. In some embodiments, the sweep gas is
introduced into the preheating zone and extracted from the
pyrolysis zone. In these or other embodiments, the sweep gas may be
introduced into each of the preheating, pyrolysis, and cooling
zones and also extracted from each of the zones.
[0207] In some embodiments, the zone or zones in which separation
is carried out is a physically separate unit from the BPU. The
separation unit or zone may be disposed between zones, if desired.
For example, there may be a separation unit placed between
pyrolysis and cooling zones.
[0208] The sweep gas may be introduced continuously, especially
when the solids flow is continuous. When the pyrolysis reaction is
operated as a batch process, the sweep gas may be introduced after
a certain amount of time, or periodically, to remove volatiles.
Even when the pyrolysis reaction is operated continuously, the
sweep gas may be introduced semi-continuously or periodically, if
desired, with suitable valves and controls.
[0209] The volatiles-containing sweep gas may exit from the one or
more zones, and may be combined if obtained from multiple zones.
The resulting gas stream, containing various vapors, may then be
fed to a process gas heater for control of air emissions, as
discussed above and illustrated in FIG. 8. Any known
thermal-oxidation unit may be employed. In some embodiments, the
process gas heater is fed with natural gas and air, to reach
sufficient temperatures for substantial destruction of volatiles
contained therein.
[0210] The effluent of the process gas heater will be a hot gas
stream comprising water, carbon dioxide, and nitrogen. This
effluent stream may be purged directly to air emissions, if
desired. In some embodiments, the energy content of the process gas
heater effluent is recovered, such as in a waste-heat recovery
unit. The energy content may also be recovered by heat exchange
with another stream (such as the sweep gas). The energy content may
be utilized by directly or indirectly heating, or assisting with
heating, a unit elsewhere in the process, such as the dryer or the
reactor. In some embodiments, essentially all of the process gas
heater effluent is employed for indirect heating (utility side) of
the dryer. The process gas heater may employ other fuels than
natural gas.
[0211] The yield of carbonaceous material may vary, depending on
the above-described factors including type of feedstock and process
conditions. In some embodiments, the net yield of solids as a
percentage of the starting feedstock, on a dry basis, is at least
25%, 30%, 35%, 40%, 45%, 50%, or higher. The remainder will be
split between condensable vapors, such as terpenes, tars, alcohols,
acids, aldehydes, or ketones; and non-condensable gases, such as
carbon monoxide, hydrogen, carbon dioxide, and methane. The
relative amounts of condensable vapors compared to non-condensable
gases will also depend on process conditions, including the water
present. In some embodiments, incorporation of an additive before a
pyrolysis step improves yield of carbonaceous material compared to
an identical process where the additive is added after the
pyrolysis step (if at all). In some embodiments, an additive (e.g.,
a halogen-containing additive) is added to wet biomass and/or after
drying the biomass but before pyrolysis and the resulting mass
yield of carbonaceous material (e.g., biogenic activated carbon) is
greater than the mass yield of a biogenic activated carbon produced
additive (i) not added at any time, or (ii) added after pyrolysis,
but by an otherwise identical process.
[0212] In terms of the carbon balance, in some embodiments the net
yield of carbon as a percentage of starting carbon in the feedstock
is at least 25%, 30%, 40%, 50%, 60%, 70%, or higher. For example,
the in some embodiments the carbonaceous material contains between
about 40% and about 70% of the carbon contained in the starting
feedstock. The rest of the carbon results in the formation of
methane, carbon monoxide, carbon dioxide, light hydrocarbons,
aromatics, tars, terpenes, alcohols, acids, aldehydes, or ketones,
to varying extents.
[0213] In alternative embodiments, some portion of these compounds
is combined with the carbon-rich solids to enrich the carbon and
energy content of the product. In these embodiments, some or all of
the resulting gas stream from the reactor, containing various
vapors, may be condensed, at least in part, and then passed over
cooled pyrolyzed solids derived from the cooling zone and/or from
the separate cooler. These embodiments are described in more detail
below.
[0214] Following the reaction and cooling within the cooling zone
(if present), the carbonaceous solids may be introduced into a
cooler. In some embodiments, solids are collected and simply
allowed to cool at slow rates. If the carbonaceous solids are
reactive or unstable in air, it may be desirable to maintain an
inert atmosphere and/or rapidly cool the solids to, for example, a
temperature less than or equal to about 40.degree. C., such as
ambient temperature. In some embodiments, a water quench is
employed for rapid cooling. In some embodiments, a fluidized-bed
cooler is employed. A "cooler" should be broadly construed to also
include containers, tanks, pipes, or portions thereof. It should be
appreciated that in various embodiments, the cooler is distinct
from the cooling unit or cooling reactor.
[0215] In some embodiments, the process further comprises operating
the cooler to cool the warm pyrolyzed solids with steam, thereby
generating the cool pyrolyzed solids and superheated steam; wherein
the drying is carried out, at least in part, with the superheated
steam derived from the cooler. Optionally, the cooler may be
operated to first cool the warm pyrolyzed solids with steam to
reach a first cooler temperature, and then with air to reach a
second cooler temperature, wherein the second cooler temperature is
lower than the first cooler temperature and is associated with a
reduced combustion risk for the warm pyrolyzed solids in the
presence of the air.
[0216] Following cooling to ambient conditions, the carbonaceous
solids may be recovered and stored, conveyed to another site
operation, transported to another site, or otherwise disposed,
traded, or sold. The solids may be fed to a unit to reduce particle
size. A variety of size-reduction units are known in the art,
including crushers, shredders, grinders, pulverizers, jet mills,
pin mills, and ball mills.
[0217] Screening or some other means for separation based on
particle size may be included. The screening may be upstream or
downstream of grinding, if present. A portion of the screened
material (e.g., large chunks) may be returned to the grinding unit.
The small and large particles may be recovered for separate
downstream uses. In some embodiments, cooled pyrolyzed solids are
ground into a fine powder, such as a pulverized carbon or activated
carbon product or increased strength.
[0218] Various additives may be introduced throughout the process,
before, during, or after any step disclosed herein. The additives
may be broadly classified as process additives, selected to improve
process performance such as carbon yield or pyrolysis
time/temperature to achieve a desired carbon purity; and product
additives, selected to improve one or more properties of the
biogenic activated carbon, or a downstream product incorporating
the reagent. Certain additives may provide enhanced process and
product characteristics, such as overall yield of biogenic
activated carbon product compared to the amount of biomass
feedstock.
[0219] The additive may be added at any suitable time during the
entire process. For example and without limitation, the additive
may be added before, during or after a feedstock drying step;
before, during or after a feedstock deaerating step; before, during
or after a pyrolysis step; before, during or after a separation
step; before, during or after any cooling step; before, during or
after a biogenic activated carbon recovery step; before, during or
after a pulverizing step; before, during or after a sizing step;
and/or before, during or after a packaging step. Additives may be
incorporated at or on feedstock supply facilities, transport
trucks, unloading equipment, storage bins, conveyors (including
open or closed conveyors), dryers, process heaters, or any other
units. Additives may be added anywhere into the pyrolysis process
itself, using suitable means for introducing additives. Additives
may be added after carbonization, or even after pulverization, if
desired.
[0220] Accordingly, one example of a single-reactor biomass
processing unit consistent with the present disclosure is depicted
in FIG. 21. Unit 2100 comprises a hopper 2104 into which feedstock
2102 is fed. Hopper 2104 is optionally configured to enable
addition and/or mixing of reactor off-gases (e.g., vapor stream
2114) and/or additives and/or gases from external sources 2162 to
feedstock 2102 before conveying the feedstock 2102 to reactor 2112.
Activated carbon 2126 is mechanically conveyed through reactor 2112
before exiting at the opposite end. Steam, nitrogen, carbon
dioxide, or a combination thereof 2152 is introduced into reactor
2112 in a countercurrent manner compared to the biomass path. Vapor
stream 2114 is removed at least in part from the reactor 2112 and
is optionally fed into hopper 2104, and then to a thermal oxidizer
2124. Heat exchanger 2154 enables heat from the emissions of the
thermal oxidizer to heat gas stream 2158, which can comprise
nitrogen and/or carbon dioxide. Gas stream 2158, or a portion
thereof, is recycled via path 2160 to the reactor 2112, and/or
optionally to the feedstock 2102 before entry into the reactor 2112
(not shown). Off-gases 2156 can be disposed of according to
standard methods, for example through a stack.
[0221] The embodiment shown in FIG. 22 illustrates a two-reactor
biomass processing unit consistent with the present disclosure.
Unit 2200 comprises a first multizone reactor unit 2212A,
configured substantially similarly to processing unit 2100
described above with respect to FIG. 21. In this embodiment,
however, at least a portion of the biogenic activated carbon 2226A
produced by reactor 2212A is fed into a hopper 2204 and then into
second reactor 2212B via path 2202. At least a portion of the
optionally thermally oxidized and optionally adjusted vapor stream
2260 produced by first reactor 2212A, thermal oxidizer 2224 and
heat exchanger 2254 is fed countercurrently into second reactor
2212B. Optionally, at least a portion of the off-gases from second
reactor 2212B are recycled via path 2272 to indirectly heat the
second reactor 2212B. Alternatively or in addition, portions of the
off-gases that are not recycled as heat can be disposed of, for
example by a stack, via path 2256B. Biogenic activated carbon
product exits second reactor 2212B via path 2226B.
[0222] In these or other embodiments, the present disclosure
provides a continuous process for producing biogenic activated
carbon, the process comprising:
[0223] (a) providing a starting carbon-containing feedstock
comprising biomass;
[0224] (b) optionally drying said feedstock to remove at least a
portion of moisture from said feedstock;
[0225] (c) in one or more indirectly heated reaction zones,
mechanically conveying said feedstock and countercurrently
contacting said feedstock with a vapor stream comprising a
substantially inert gas and an activation agent comprising at least
one of water or carbon dioxide, to generate solids, condensable
vapors, and non-condensable gases, wherein said condensable vapors
and said non-condensable gases enter said vapor stream;
[0226] (d) removing at least a portion of said vapor stream from
said reaction zone, to generate a separated vapor stream;
[0227] (e) recycling at least a portion of said separated vapor
stream, or a thermally treated form thereof, to said feedstock
prior to step (c) and/or to a gas inlet of said reaction zone(s);
and
[0228] (f) recovering at least a portion of said solids from said
reaction zone(s) as biogenic activated carbon.
[0229] In some embodiments, step (b) is carried out to remove at
least a portion of moisture contained within the feedstock. For
example, the feedstock may be dried to contain about 12 wt % or
less moisture, such as about 8 wt % or about 4 wt % or less
moisture. In certain embodiments, no additional water is added to
the feedstock. The activation agent may include water that is
derived from moisture contained originally in the feedstock.
[0230] In some embodiments, the activation agent includes both
water and carbon dioxide. The ratio of water to carbon dioxide may
be optimized to increase activation of the solids.
[0231] At least one of the indirectly heated reaction zones is
preferably maintained at a reaction temperature selected from about
700.degree. C. to about 900.degree. C. All of the indirectly heated
reaction zones are maintained at a maximum reaction temperature
less than or equal to about 950.degree. C., in some
embodiments.
[0232] In some embodiments, step (d) comprises removing at least a
portion of the condensable vapors from the reaction zone. In some
embodiments, step (d) comprises removing all of the vapor stream
from the reaction zone.
[0233] In some embodiments, step (e) comprises introducing at least
some of the separated vapor stream to the gas inlet of the reaction
zone and/or to the feedstock prior to step (c). In some
embodiments, step (e) comprises introducing a thermally treated
form of at least some of the separated vapor stream to the gas
inlet of the reaction zone and/or to the feedstock prior to step
(c).
[0234] In some embodiments, step (e) further comprises additional
heating of the separated vapor stream, or a thermally treated form
thereof. In some embodiments, step (e) further comprises adjusting
gas composition of the separated vapor stream, or a thermally
treated form thereof. Adjusting gas composition may include
introducing one or more species selected from the group consisting
of water, carbon dioxide, nitrogen, and oxygen.
[0235] In some embodiments, the adjusted gas composition comprises
from 0% to 100% water, for example about 0%, about 1%, about 2%,
about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about
9%, about 10%, about 11%, about 12%, about 13%, about 14%, about
15%, about 16%, about 17%, about 18%, about 19%, about 20%, about
21%, about 22%, about 23%, about 24%, about 25%, about 26%, about
27%, about 28%, about 29%, about 30%, about 31%, about 32%, about
33%, about 34%, about 35%, about 36%, about 37%, about 38%, about
39%, about 40%, about 41%, about 42%, about 43%, about 44%, about
45%, about 46%, about 47%, about 48%, about 49%, about 50%, about
51%, about 52%, about 53%, about 54%, about 55%, about 56%, about
57%, about 58%, about 59%, about 60%, about 61%, about 62%, about
63%, about 64%, about 65%, about 66%, about 67%, about 68%, about
69%, about 70%, about 71%, about 72%, about 73%, about 74%, about
75%, about 76%, about 77%, about 78%, about 79%, about 80%, about
81%, about 82%, about 83%, about 84%, about 85%, about 86%, about
87%, about 88%, about 89%, about 90%, about 91%, about 92%, about
93%, about 94%, about 95%, about 96%, about 97%, about 98%, about
99%, or about 100% water.
[0236] In some embodiments, the adjusted gas composition comprises
from 0% to 100% carbon dioxide, for example about 0%, about 1%,
about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about
8%, about 9%, about 10%, about 11%, about 12%, about 13%, about
14%, about 15%, about 16%, about 17%, about 18%, about 19%, about
20%, about 21%, about 22%, about 23%, about 24%, about 25%, about
26%, about 27%, about 28%, about 29%, about 30%, about 31%, about
32%, about 33%, about 34%, about 35%, about 36%, about 37%, about
38%, about 39%, about 40%, about 41%, about 42%, about 43%, about
44%, about 45%, about 46%, about 47%, about 48%, about 49%, about
50%, about 51%, about 52%, about 53%, about 54%, about 55%, about
56%, about 57%, about 58%, about 59%, about 60%, about 61%, about
62%, about 63%, about 64%, about 65%, about 66%, about 67%, about
68%, about 69%, about 70%, about 71%, about 72%, about 73%, about
74%, about 75%, about 76%, about 77%, about 78%, about 79%, about
80%, about 81%, about 82%, about 83%, about 84%, about 85%, about
86%, about 87%, about 88%, about 89%, about 90%, about 91%, about
92%, about 93%, about 94%, about 95%, about 96%, about 97%, about
98%, about 99%, or about 100% carbon dioxide.
[0237] In some embodiments, the adjusted gas composition comprises
from 0% to 100% nitrogen, for example about 0%, about 1%, about 2%,
about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about
9%, about 10%, about 11%, about 12%, about 13%, about 14%, about
15%, about 16%, about 17%, about 18%, about 19%, about 20%, about
21%, about 22%, about 23%, about 24%, about 25%, about 26%, about
27%, about 28%, about 29%, about 30%, about 31%, about 32%, about
33%, about 34%, about 35%, about 36%, about 37%, about 38%, about
39%, about 40%, about 41%, about 42%, about 43%, about 44%, about
45%, about 46%, about 47%, about 48%, about 49%, about 50%, about
51%, about 52%, about 53%, about 54%, about 55%, about 56%, about
57%, about 58%, about 59%, about 60%, about 61%, about 62%, about
63%, about 64%, about 65%, about 66%, about 67%, about 68%, about
69%, about 70%, about 71%, about 72%, about 73%, about 74%, about
75%, about 76%, about 77%, about 78%, about 79%, about 80%, about
81%, about 82%, about 83%, about 84%, about 85%, about 86%, about
87%, about 88%, about 89%, about 90%, about 91%, about 92%, about
93%, about 94%, about 95%, about 96%, about 97%, about 98%, about
99%, or about 100% nitrogen.
[0238] In some embodiments, the adjusted gas composition comprises
from 0% to 100% oxygen, for example about 0%, about 1%, about 2%,
about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about
9%, about 10%, about 11%, about 12%, about 13%, about 14%, about
15%, about 16%, about 17%, about 18%, about 19%, about 20%, about
21%, about 22%, about 23%, about 24%, about 25%, about 26%, about
27%, about 28%, about 29%, about 30%, about 31%, about 32%, about
33%, about 34%, about 35%, about 36%, about 37%, about 38%, about
39%, about 40%, about 41%, about 42%, about 43%, about 44%, about
45%, about 46%, about 47%, about 48%, about 49%, about 50%, about
51%, about 52%, about 53%, about 54%, about 55%, about 56%, about
57%, about 58%, about 59%, about 60%, about 61%, about 62%, about
63%, about 64%, about 65%, about 66%, about 67%, about 68%, about
69%, about 70%, about 71%, about 72%, about 73%, about 74%, about
75%, about 76%, about 77%, about 78%, about 79%, about 80%, about
81%, about 82%, about 83%, about 84%, about 85%, about 86%, about
87%, about 88%, about 89%, about 90%, about 91%, about 92%, about
93%, about 94%, about 95%, about 96%, about 97%, about 98%, about
99%, or about 100% oxygen. In some embodiments, the adjusted gas
composition comprises no more than about 16%, no more than about
14%, no more than about 12%, no more than about 10%, no more than
about 8%, no more than about 6%, no more than about 4%, or no more
than about 2% of oxygen.
[0239] The separated vapor stream, or a thermally treated form
thereof, may contain, or be adjusted to contain, less than or equal
to about 1 wt % (such as about 0.1, 0.2, 0.5, or 0.8 wt %) combined
carbon monoxide and VOC content. The gas composition may be
adjusted to contain at least about 70 wt %, at least about 75%
nitrogen, at least about 80% nitrogen, at least about 85% nitrogen,
at least about 90% nitrogen, at least about 95% nitrogen, or about
100% nitrogen, in some embodiments.
[0240] At least some of the separated vapor stream, or a thermally
treated form thereof, may be introduced to a delivery system
configured for mechanically feeding the feedstock into a first
indirectly heated reaction zone. Such a delivery system may include
a feed auger or screw, for example.
[0241] In some embodiments, at least some of the activation agent
is derived from the separated vapor stream, or a thermally treated
form thereof. Step (e) may increase the yield of carbon in the
solids. Additionally, step (e) preferably increases the surface
area and Iodine Number of the solids. In some embodiments, step (f)
comprises recovering all of the solids from the reaction zone as
biogenic activated carbon.
[0242] An additive is optionally introduced before, during, or
after one or more of steps (a)-(f), and wherein the additive is
selected from an acid, a base, a salt, a metal, a metal oxide, a
metal hydroxide, a metal halide, iodine, an iodine compound, or a
combination thereof. The additive may be selected from the group
consisting of magnesium, manganese, aluminum, nickel, iron,
chromium, silicon, boron, cerium, molybdenum, phosphorus, tungsten,
vanadium, iron chloride, iron bromide, magnesium oxide, dolomite,
dolomitic lime, fluorite, fluorospar, bentonite, calcium oxide,
lime, sodium hydroxide, potassium hydroxide, hydrogen bromide,
hydrogen chloride, sodium silicate, potassium permanganate, organic
acids, iodine, an iodine compound, and combinations thereof.
[0243] The biogenic activated carbon may be characterized by an
Iodine Number of at least about 500, 1000, 1500, or 2000. The
biogenic activated carbon may be characterized by a surface area of
at least about 1000 m.sup.2/g, 1500 m.sup.2/g, 2000 m.sup.2/g, or
higher.
[0244] In some embodiments, at least a portion of the biogenic
activated carbon is present in the form of graphene. The biogenic
activated carbon may be responsive to an externally applied
magnetic field. Also, the biogenic activated carbon may have a
higher electrical conductance and/or capacitance than the starting
carbon-containing feedstock.
[0245] In some embodiments, the biogenic activated carbon is
responsive to an externally applied magnetic field. In some
embodiments, the magnetic properties of the biogenic activated
carbon are due at least in part to the presence of a magnetic metal
or compound thereof, such as iron. In other embodiments, the
biogenic activated carbon is responsive to an externally applied
magnetic field notwithstanding the presence of iron, an iron
compound, another magnetic metal or compound thereof, an ore, a
metalloid or compound thereof, or another non-graphene material
that itself responds to an externally applied magnetic field. That
is, in some embodiments, the biogenic activated carbon is
responsive to an externally applied magnetic field to an extent
beyond that which can be attributed to the presence of iron, an
iron compound, another magnetic metal or compound thereof, an ore,
a metalloid or compound thereof, or another non-graphene material
that itself responds to an externally applied magnetic field.
[0246] In certain embodiments, the process further comprises
introducing at least some of the separated vapor stream, or a
thermally treated form thereof, to a reactor for growing graphene
on a substrate in two or three dimensions. In such a process, the
carbon contained in the vapor is deposited onto a substrate (such
as silicon) to form single layers of carbon. The substrate may be a
layer or a three-dimensional object.
[0247] The liquid or vapor stream from an external source may vary
widely. Exemplary vapor streams may include CO, CO.sub.2, CH.sub.4,
light hydrocarbons, tars, etc. Exemplary liquid streams may include
heavier hydrocarbons (including olefins or aromatics), methanol,
ethanol, or heavier alcohols, organic acids, aldehydes, etc. The
external source may be a VOC off-gas stream from an adjacent or
co-located chemical or fuel plant, for example. Combinations are
possible, including not only liquid/vapor streams but also mixtures
of external sources with recycled gases within the system, i.e.,
the separated vapor stream, or a thermally treated form
thereof.
[0248] In some embodiments, the present disclosure provides a
continuous process for producing graphene, the process comprising:
[0249] (a) providing a starting carbon-containing feedstock
comprising biomass; [0250] (b) optionally drying said feedstock to
remove at least a portion of moisture from said feedstock; [0251]
(c) in one or more indirectly heated reaction zones, mechanically
conveying said feedstock and countercurrently contacting said
feedstock with a vapor stream comprising a substantially inert gas
and an activation agent including at least one of water or carbon
dioxide, to generate solids, condensable vapors, and
non-condensable gases, wherein said condensable vapors and said
non-condensable gases enter said vapor stream; [0252] (d) removing
at least a portion of said vapor stream from said reaction zone, to
generate a separated vapor stream; [0253] (e) recycling at least a
portion of said separated vapor stream, or a thermally treated form
thereof, to said feedstock prior to step (c) and/or to a gas inlet
of said reaction zone(s); and [0254] (f) recovering at least a
portion of said solids from said reaction zone(s) as graphene.
[0255] In some embodiments, the solids recovered in step (f)
consist of graphene-containing biogenic activated carbon. The
graphene-containing biogenic activated carbon may contain widely
varying fractions of graphene relative to total carbon present. For
example, the mass (or mole) ratio of carbon present as graphene to
total carbon in the biogenic activated carbon may be from about
0.0001 to about 1, such as about 0.001, about 0.005, about 0.01,
about 0.005, about 0.1, about 0.15, about 0.2, about 0.25, about
0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about
0.9, about 0.95, or higher.
[0256] It should also be noted that the graphene content is not
necessarily uniform throughout the biogenic activated carbon. In
some embodiments, it is believed (without being limited by
hypothesis) that graphene is grown from carbon-containing vapors
that pass over the pyrolyzed or pyrolyzing feedstock, the graphene
may be primarily present at or near the surface of the resulting
solids. In other embodiments, with sufficient heat and mass
transport into the solids, graphene formation may occur essentially
throughout the solids.
[0257] The process may further comprise separating graphene from
the graphene-containing biogenic activated carbon. The separation
may be achieved by mechanical, magnetic, or electrical means, such
as by a centrifuge, magnetic separator, or electrostatic
precipitator, respectively.
[0258] In some embodiments, the solids are further treated to
increase graphene content in the solids. For example, a catalyst
may be introduced to enhance graphene growth. The solids may be
introduced to a separate process to fabricate or transfer graphene
on a substrate or on a device.
[0259] In some embodiments, an external source of carbon is
introduced to increase surface area and/or increase carbon yield
and/or increase graphene content. In some of these embodiments, a
continuous process for producing biogenic activated carbon
comprises: [0260] (a) providing a starting carbon-containing
feedstock comprising biomass; [0261] (b) optionally drying said
feedstock to remove at least a portion of moisture from said
feedstock; [0262] (c) in one or more indirectly heated reaction
zones, mechanically conveying said feedstock and countercurrently
contacting said feedstock with a vapor stream comprising a
substantially inert gas and an activation agent including at least
one of water or carbon dioxide, to generate solids, condensable
vapors, and non-condensable gases, wherein said condensable vapors
and said non-condensable gases enter said vapor stream; [0263] (d)
removing at least a portion of said vapor stream from said reaction
zone, to generate a separated vapor stream; [0264] (e) recycling at
least a portion of said separated vapor stream, or a thermally
treated form thereof, to said feedstock prior to step (c) and/or to
a gas inlet of said reaction zone(s); and [0265] (f) recovering at
least a portion of said solids from said reaction zone(s), wherein
said solids include graphene-containing biogenic activated
carbon.
[0266] In one embodiment, a continuous process for producing
graphene-containing biogenic activated carbon comprises: [0267] (a)
providing a starting carbon-containing feedstock comprising
biomass; [0268] (b) optionally drying said feedstock to remove at
least a portion of moisture from said feedstock; [0269] (c) in one
or more indirectly heated reaction zones, mechanically conveying
said feedstock and countercurrently contacting said feedstock with
a vapor stream comprising a substantially inert gas and an
activation agent including at least one of water or carbon dioxide,
to generate solids, condensable vapors, and non-condensable gases,
wherein said condensable vapors and said non-condensable gases
enter said vapor stream; [0270] (d) removing at least a portion of
said vapor stream from said reaction zone, to generate a separated
vapor stream; [0271] (e) recycling at least a portion of said
separated vapor stream, or a thermally treated form thereof, to
said feedstock prior to step (c) and/or to a gas inlet of said
reaction zone(s); and [0272] (f) recovering at least a portion of
said solids from said reaction zone(s), wherein said solids include
graphene-containing biogenic activated carbon.
[0273] In some embodiments, the process further comprises treating
the solids recovered in step (f) to increase graphene content. In
some embodiments, the process further comprises using at least a
portion of the solids recovered in step (f) to fabricate graphene
on a substrate or a device.
[0274] In some embodiments, the graphene or graphene-containing
biogenic activated carbon is responsive to an externally applied
magnetic field. In some embodiments, the graphene or
graphene-containing biogenic activated carbon has an electrical
conductance value and/or an electrical capacitance value that is
greater than the carbon-containing feedstock.
[0275] In some embodiments, the present disclosure provides a
continuous process for producing graphene-containing biogenic
activated carbon, the process comprising:
[0276] (a) providing a starting carbon-containing feedstock
comprising biomass;
[0277] (b) optionally drying said feedstock to remove at least a
portion of moisture from said feedstock;
[0278] (c) in one or more indirectly heated reaction zones,
mechanically conveying said feedstock and countercurrently
contacting said feedstock with a vapor stream comprising a
substantially inert gas and an activation agent comprising at least
one of water or carbon dioxide, to generate solids, condensable
vapors, and non-condensable gases, wherein said condensable vapors
and said non-condensable gases enter said vapor stream;
[0279] (d) removing at least a portion of said vapor stream from
said reaction zone, to generate a separated vapor stream;
[0280] (e) recycling at least a portion of said separated vapor
stream, or a thermally treated form thereof, to said feedstock
prior to step (c) and/or to a gas inlet of said reaction zone(s),
to increase the surface area of carbon in said solids; and
[0281] (f) recovering at least a portion of said solids from said
reaction zone(s) as biogenic activated carbon, wherein said
biogenic activated carbon comprises, on a dry basis, about 55 wt %
or more total carbon, about 15 wt % or less hydrogen, and less than
or equal to about 1 wt % nitrogen, wherein at least a portion of
said biogenic activated carbon is present in the form of graphene,
wherein said biogenic activated carbon composition is characterized
by an Iodine Number higher than about 500, and wherein said
biogenic activated carbon is responsive to an externally applied
magnetic field.
[0282] In some variations, the present disclosure provides a
process for producing a biogenic activated carbon product, the
process comprising: [0283] (a) providing a carbon-containing
feedstock comprising biomass; [0284] (a') adding an additive to the
feedstock to produce an enhanced feedstock; [0285] (b) optionally
drying the enhanced feedstock to produce a dried enhanced
feedstock; [0286] (c) optionally deaerating the enhanced feedstock
or the dried enhanced feedstock to remove at least a portion of
interstitial oxygen, if any, contained with the enhanced feedstock
or the dried enhanced feedstock; [0287] (d) in a pyrolysis zone,
pyrolyzing the feedstock produced in any of steps (a'), (b) or (c),
or a combination thereof, in the presence of a substantially inert
gas for at least about 10 minutes and with a pyrolysis temperature
selected from about 250.degree. C. to about 700.degree. C., to
generate hot pyrolyzed solids, condensable vapors, and
non-condensable gases; [0288] (e) separating at least a portion of
the condensable vapors and at least a portion of the
non-condensable gases from the hot pyrolyzed solids; [0289] (f) in
a cooling zone, cooling the hot pyrolyzed solids, in the presence
of the substantially inert gas for at least about 5 minutes and
with a cooling-zone temperature less than or equal to about the
pyrolysis temperature, to generate warm pyrolyzed solids; [0290]
(g) in an optional cooler that is separate from the cooling zone,
further cooling the warm pyrolyzed solids to generate cool
pyrolyzed solids; [0291] (h) recovering a biogenic activated carbon
product comprising at least a portion of the warm or cool pyrolyzed
solids; and [0292] (i) pulverizing said biogenic activated carbon
composition to reduce average particle size of said biogenic
activated carbon composition.
[0293] Some embodiments provide a process for producing a biogenic
activated carbon composition, said process comprising: [0294] (a)
providing a carbon-containing feedstock comprising biomass; [0295]
(a') adding an additive to the feedstock to produce an enhanced
feedstock; [0296] (b) optionally drying the enhanced feedstock to
produce a dried enhanced feedstock; [0297] (c) optionally
deaerating the enhanced feedstock or the dried enhanced feedstock
to remove at least a portion of interstitial oxygen, if any,
contained with the enhanced feedstock or the dried enhanced
feedstock; [0298] (d) in a pyrolysis zone, pyrolyzing the feedstock
produced in any of steps (a'), (b) or (c), or a combination
thereof, in the presence of a substantially inert gas for at least
10 minutes and with a pyrolysis temperature selected from about
250.degree. C. to about 700.degree. C., to generate hot pyrolyzed
solids, condensable vapors, and non-condensable gases; [0299] (e)
separating at least a portion of said condensable vapors and at
least a portion of said non-condensable gases from said hot
pyrolyzed solids; [0300] (f) in a cooling zone, cooling said hot
pyrolyzed solids, in the presence of said substantially inert gas
for at least 5 minutes and with a cooling temperature less than or
equal to about said pyrolysis temperature, to generate warm
pyrolyzed solids; [0301] (g) in an optional cooler that is separate
from said cooling zone, cooling said warm pyrolyzed solids to
generate cool pyrolyzed solids; [0302] (h) recovering a biogenic
activated carbon composition comprising at least a portion of said
cool pyrolyzed solids; and [0303] (i) pulverizing said biogenic
activated carbon composition to reduce average particle size of
said biogenic activated carbon composition.
[0304] In some embodiments, the process comprises adding an
additive before the pyrolysis step. In such embodiments, the
resulting biogenic activated carbon may be produced in a mass yield
that is higher than biogenic activated carbon produced without
additive, or with additive added during or after the pyrolysis step
but by an otherwise identical method. In a related embodiment, the
biogenic activated carbon product performs as well as or better
than the comparable biogenic activated carbon product. In some
embodiments, the process requires less energy input to produce a
biogenic activated carbon product when an additive is added before
the pyrolysis step. In some embodiments, the resulting biogenic
activated carbon has a higher fixed carbon content compared to a
biogenic activated carbon produced without additive (or with
additive added during or after the pyrolysis step) but by an
otherwise identical process. In some embodiments, the additive is
distributed more thoroughly and/or evenly throughout the biogenic
activated carbon as compared to biogenic activated carbon produced
by the same process but wherein the additive is added during or
after the pyrolysis step. In some embodiments, the biogenic
activated carbon requires less additive to achieve a desired
performance characteristic when added before the pyrolysis step
compared to a biogenic activated carbon produced by an otherwise
identical process but wherein the additive is added during or after
the pyrolysis step.
[0305] In some embodiments, an additive is selected from a metal, a
metal oxide, a metal hydroxide, or a combination thereof. For
example an additive may be selected from, but is by no means
limited to, magnesium, manganese, aluminum, nickel, chromium,
silicon, boron, cerium, molybdenum, phosphorus, tungsten, vanadium,
iron halide, iron chloride, iron bromide, magnesium oxide,
dolomite, dolomitic lime, fluorite, fluorospar, bentonite, calcium
oxide, lime, and combinations thereof.
[0306] In some embodiments, an additive is selected from an acid, a
base, or a salt thereof. For example an additive may be selected
from, but is by no means limited to, sodium hydroxide, potassium
hydroxide, magnesium oxide, hydrogen bromide, hydrogen chloride,
sodium silicate, potassium permanganate, organic acids (e.g.,
citric acid), or combinations thereof.
[0307] In some embodiments, an additive is selected from a metal
halide. Metal halides are compounds between metals and halogens
(fluorine, chlorine, bromine, iodine, and astatine). The halogens
can form many compounds with metals. Metal halides are generally
obtained by direct combination, or more commonly, neutralization of
basic metal salt with a hydrohalic acid. In some embodiments, an
additive is selected from iron halide (FeX.sub.2 and/or FeX.sub.3),
iron chloride (FeCl.sub.2 and/or FeCl.sub.3), iron bromide
(FeBr.sub.2 and/or FeBr.sub.3), or hydrates thereof, and any
combinations thereof.
[0308] In some variations, a biogenic activated carbon composition
comprises, on a dry basis:
[0309] 55 wt % or more total carbon;
[0310] 15 wt % or less hydrogen;
[0311] 1 wt % or less nitrogen;
[0312] 0.5 wt % or less phosphorus;
[0313] 0.2 wt % or less sulfur; [0314] an additive selected from an
acid, a base, a salt, a metal, a metal oxide, a metal hydroxide, a
metal halide, iodine, an iodine compound, or a combination
thereof
[0315] In some embodiments, the additive comprises iodine or an
iodine compound, or a combination of iodine and one or more iodine
compounds. When the additive comprises iodine, it may be present in
the biogenic activated carbon composition as absorbed or
intercalated molecular I.sub.2, as physically or chemically
adsorbed molecular I.sub.2, as absorbed or intercalated atomic I,
as physically or chemically adsorbed atomic I, or any combination
thereof.
[0316] When the additive comprises one or more iodine compounds,
they may be selected from the group consisting of iodide ion,
hydrogen iodide, an iodide salt, a metal iodide, ammonium iodide,
an iodine oxide, triiodide ion, a triiodide salt, a metal
triiodide, ammonium triiodide, iodate ion, an iodate salt, a
polyiodide, iodoform, iodic acid, methyl iodide, an iodinated
hydrocarbon, periodic acid, orthoperiodic acid, metaperiodic acid,
and combinations, salts, acids, bases, or derivatives thereof.
[0317] In some variations, the biogenic activated carbon
composition is produced by a process comprising at least the steps
of: [0318] (a) providing a carbon-containing feedstock comprising
biomass; [0319] (b) optionally drying the feedstock to remove at
least a portion of moisture contained within the feedstock; [0320]
(c) optionally deaerating the feedstock to remove at least a
portion of interstitial oxygen, if any, contained with the
feedstock; [0321] (d) in a pyrolysis zone, pyrolyzing the feedstock
in the presence of a substantially inert gas for at least 10
minutes and with a pyrolysis temperature selected from about
250.degree. C. to about 700.degree. C., to generate hot pyrolyzed
solids, condensable vapors, and non-condensable gases; [0322] (e)
separating at least a portion of the condensable vapors and at
least a portion of the non-condensable gases from the hot pyrolyzed
solids; [0323] (f) in a cooling zone, cooling the hot pyrolyzed
solids, in the presence of the substantially inert gas for at least
5 minutes and with a cooling temperature less than or equal to
about the pyrolysis temperature, to generate warm pyrolyzed solids;
[0324] (g) in a cooling unit that is separate from the cooling
zone, cooling the warm pyrolyzed solids to generate cool pyrolyzed
solids; [0325] (h) recovering a biogenic activated carbon
composition comprising at least a portion of the cool pyrolyzed
solids; and [0326] (i) pulverizing the biogenic activated carbon
composition to reduce average particle size of the biogenic
activated carbon composition.
[0327] In some variations, a process for producing a biogenic
activated carbon composition, the process comprising: [0328] (a)
providing a carbon-containing feedstock comprising biomass; [0329]
(b) optionally drying the feedstock to remove at least a portion of
moisture contained within the feedstock; [0330] (c) optionally
deaerating the feedstock to remove at least a portion of
interstitial oxygen, if any, contained with the feedstock; [0331]
(d) in a pyrolysis zone, pyrolyzing the feedstock in the presence
of a substantially inert gas for at least 10 minutes and with a
pyrolysis temperature selected from about 250.degree. C. to about
700.degree. C., to generate hot pyrolyzed solids, condensable
vapors, and non-condensable gases; [0332] (e) separating at least a
portion of the condensable vapors and at least a portion of the
non-condensable gases from the hot pyrolyzed solids; [0333] (f) in
a cooling zone, cooling the hot pyrolyzed solids, in the presence
of the substantially inert gas for at least 5 minutes and with a
cooling temperature less than or equal to about the pyrolysis
temperature, to generate warm pyrolyzed solids; [0334] (g) in a
cooling unit that is separate from the cooling zone, cooling the
warm pyrolyzed solids to generate cool pyrolyzed solids; [0335] (h)
recovering a biogenic activated carbon composition comprising at
least a portion of the cool pyrolyzed solids; and [0336] (i)
pulverizing the biogenic activated carbon composition to reduce
average particle size of the biogenic activated carbon composition,
[0337] wherein an additive is introduced before, during, or after
one or more of steps (a)-(i), and wherein the additive is selected
from an acid, a base, a salt, a metal, a metal oxide, a metal
hydroxide, a metal halide, iodine, an iodine compound, or a
combination thereof.
[0338] In some embodiments, the additive comprises iodine or an
iodine compound, or a combination of iodine and one or more iodine
compounds, optionally dissolved in a solvent. Various solvents for
iodine or iodine compounds are known in the art. For example, alkyl
halides such as (but not limited to) n-propyl bromide or n-butyl
iodide may be employed. Alcohols such as methanol or ethanol may be
used. In some embodiments, a tincture of iodine may be employed to
introduce the additive into the composition.
[0339] In some embodiments, the additive comprises iodine that is
introduced as a solid that sublimes to iodine vapor for
incorporation into the biogenic activated carbon composition. At
room temperature, iodine is a solid. Upon heating, the iodine
sublimes into a vapor. Thus, solid iodine particles may be
introduced into any stream, vessel, pipe, or container (e.g. a
barrel or a bag) that also contains the biogenic activated carbon
composition. Upon heating the iodine particles will sublime, and
the I.sub.2 vapor can penetrate into the carbon particles, thus
incorporating iodine as an additive on the surface of the particles
and potentially within the particles.
[0340] In one embodiment, the present disclosure provides a method
of reducing or removing at least one contaminant from a gas-phase
emission stream, said method comprising: [0341] (a) providing a
gas-phase emissions stream comprising at least one contaminant;
[0342] (b) contacting the gas-phase emissions stream with an
additive and activated carbon particles comprising a biogenic
activated carbon composition to generate contaminant-adsorbed
particles; and [0343] (c) separating at least a portion of said
contaminant-adsorbed particles from said gas-phase emissions stream
to produce a contaminant-reduced gas-phase emissions stream.
[0344] In some embodiments, the activated carbon particles further
comprise the additive. In some embodiments, step (b) comprises
directly adding the additive to said gas-phase emissions stream. In
some embodiments, the additive is selected from the group
consisting of an acid, a base, a salt, a metal, a metal oxide, a
metal hydroxide, a metal halide, iodine, an iodine compound, and
combinations thereof. In some embodiments, the additive is selected
from the group consisting of magnesium, manganese, aluminum,
nickel, iron, chromium, silicon, boron, cerium, molybdenum,
phosphorus, tungsten, vanadium, iron chloride, iron bromide,
magnesium oxide, dolomite, dolomitic lime, fluorite, fluorospar,
bentonite, calcium oxide, lime, sodium hydroxide, potassium
hydroxide, hydrogen bromide, hydrogen chloride, sodium silicate,
potassium permanganate, organic acids, iodine, an iodine compound,
and combinations thereof. In some embodiments, the contaminant is a
metal selected from the group consisting of mercury, boron,
selenium, arsenic, compounds thereof, salts thereof and mixtures
thereof. In some embodiments, the contaminant is a hazardous air
pollutant. In some embodiments, the contaminant is a volatile
organic compound. In some embodiments, the contaminant is a
non-condensable gas selected from the group consisting of nitrogen
oxides, carbon monoxide, carbon dioxide, hydrogen sulfide, sulfur
dioxide, sulfur trioxide, methane, ethane, ethylene, ozone,
ammonia, and combinations thereof.
[0345] In some embodiments, the contaminant-adsorbed carbon
particles include at least one contaminant selected from the group
consisting of carbon dioxide, nitrogen oxides, mercury, sulfur
dioxide, absorbed forms thereof, adsorbed forms thereof, reacted
forms thereof, or mixtures thereof.
[0346] In some embodiments, the gas-phase emissions stream is
derived from, arises out of, or is produced by combustion of a fuel
comprising said biogenic activated carbon composition. In some
embodiments, the gas-phase emissions stream is derived from, arises
out of, or is produced by co-combustion of coal and said biogenic
activated carbon composition.
[0347] In some embodiments, the method further comprises (d)
treating said contaminant-adsorbed carbon particles to regenerate
said activated carbon particles.
[0348] In some embodiments, the method further comprises (d')
combusting said contaminant-adsorbed carbon particles to generate
energy.
[0349] In one embodiment, a method of using a biogenic activated
carbon composition to reduce mercury emissions comprises: [0350]
(a) providing a gas-phase emissions stream comprising mercury;
[0351] (b) contacting the gas-phase emissions stream with
activated-carbon particles comprising a biogenic activated carbon
composition comprising iron or an iron-containing compound to
generate mercury-adsorbed carbon particles; and [0352] (c)
separating at least a portion of said mercury-adsorbed carbon
particles from said gas-phase emissions stream using electrostatic
precipitation, to produce a mercury-reduced gas-phase emissions
stream.
[0353] In some embodiments, the presence of said iron or an
iron-containing compound in the activated-carbon particles enhances
said electrostatic precipitation during step (c), thereby improving
mercury control.
[0354] In some embodiments, the method further comprises: (d)
separating at least a portion of the mercury-adsorbed carbon
particles from other electrostatic precipitates formed in step (c).
In some embodiments, step (d) comprises exposing said
mercury-adsorbed carbon particles to a magnetic field.
[0355] In some embodiments, a process for producing energy
comprises: [0356] (a) providing a carbon-containing feedstock
comprising a biogenic activated carbon composition; and [0357] (b)
oxidizing said carbon-containing feedstock to generate energy and a
gas-phase emissions stream comprising at least one contaminant,
wherein the biogenic activated carbon composition adsorbs at least
a portion of the at least one contaminant.
[0358] In some embodiments, the carbon-containing feedstock
comprises the at least one contaminant, or a precursor thereof. In
some embodiments, the carbon-containing feedstock further comprises
biomass. In some embodiments, the carbon-containing feedstock
further comprises coal. In some embodiments, the carbon-containing
feedstock consists essentially of said biogenic activated carbon
composition. In some embodiments, the at least one contaminant
comprises a metal selected from the group consisting of mercury,
boron, selenium, arsenic, a compound thereof, a salt thereof, and
mixtures thereof. In some embodiments, the at least one contaminant
comprises a hazardous air pollutant or volatile organic compound.
In some embodiments, the at least one contaminant comprises a
non-condensable gas selected from the group consisting of nitrogen
oxides, carbon monoxide, carbon dioxide, hydrogen sulfide, sulfur
dioxide, sulfur trioxide, methane, ethane, ethylene, ozone,
ammonia, and combinations thereof. In some embodiments, the
biogenic activated carbon composition comprises an additive
selected from the group consisting of an acid, a base, a salt, a
metal, a metal oxide, a metal hydroxide, a metal halide, iodine, an
iodine compound, and combinations thereof. In some embodiments, the
additive is selected from the group consisting of magnesium,
manganese, aluminum, nickel, iron, chromium, silicon, boron,
cerium, molybdenum, phosphorus, tungsten, vanadium, iron chloride,
iron bromide, magnesium oxide, dolomite, dolomitic lime, fluorite,
fluorospar, bentonite, calcium oxide, lime, sodium hydroxide,
potassium hydroxide, hydrogen bromide, hydrogen chloride, sodium
silicate, potassium permanganate, organic acids, iodine, an iodine
compound, and combinations thereof.
[0359] In any method of use disclosed herein, the biogenic
activated carbon composition may have a heat value of at least
about 5,000 BTU/lb, for example about 5,000, at least about 6,000,
at least about 7,000, at least about 8,000, at least about 9,000,
at least about 10,000, at least about 11,000, at least about
12,000, or greater than about 12,000 BTU/lb.
[0360] In any method of use disclosed herein, biogenic activated
carbon compositions as disclosed herein may be added to (e.g. mixed
with) fuel anywhere in a fuel delivery, fuel storage, fuel
preparation, or fuel mixing process in any suitable location, such
as a fuel yard, in storage bins, on conveyors, in mixers, during
injection, etc. Alternatively or in addition to the foregoing,
biogenic activated carbon may be added to a combustion zone either
mixed with, or independent from, other fuel source(s). For example
and without limitation, in some embodiments the biogenic activated
carbon composition is provided at or before a combustion zone, at
or before a burner tip, and/or before or concurrently with a step
of oxidizing the carbon-containing feedstock.
[0361] In one embodiment, a method of using a biogenic activated
carbon composition to purify a liquid comprises: [0362] (a)
providing a liquid comprising at least one contaminant; and [0363]
(b) contacting said liquid with an additive and activated-carbon
particles comprising a biogenic activated carbon composition to
generate contaminant-adsorbed carbon particles and a
contaminant-reduced liquid.
[0364] In some embodiments, the activated carbon particles comprise
said additive. In some embodiments, the additive is selected from
the group consisting of an acid, a base, a salt, a metal, a metal
oxide, a metal hydroxide, a metal halide, iodine, an iodine
compound, and combinations thereof. In some embodiments, the
additive is selected from the group consisting of magnesium,
manganese, aluminum, nickel, iron, chromium, silicon, boron,
cerium, molybdenum, phosphorus, tungsten, vanadium, iron chloride,
iron bromide, magnesium oxide, dolomite, dolomitic lime, fluorite,
fluorospar, bentonite, calcium oxide, lime, sodium hydroxide,
potassium hydroxide, hydrogen bromide, hydrogen chloride, sodium
silicate, potassium permanganate, organic acids, iodine, an iodine
compound, and combinations thereof. In some embodiments, the at
least one contaminant is a metal selected from the group consisting
of arsenic, boron, selenium, mercury, a compound thereof, a salt
thereof, and mixtures thereof. In some embodiments, the at least
one contaminant comprises an organic compound. In some embodiments,
the at least one contaminant comprises a halogen. In some
embodiments, the at least one contaminant comprises hydrogen
sulfide. In some embodiments, the at least one contaminant
comprises a chlorination by-product. In some embodiments, the at
least one contaminant comprises a pesticide or herbicide. In some
embodiments, the liquid comprises water.
[0365] In some embodiments, the method further comprises treating
the contaminant-adsorbed carbon particles to regenerate said
activated-carbon particles. In some embodiments, the method further
comprises combusting the contaminant-adsorbed carbon particles to
generate energy.
[0366] In one embodiment, the present disclosure provides a method
of removing at least a portion of a sulfur contaminant from a
liquid comprising: [0367] (a) providing a liquid comprising a
sulfur contaminant; and [0368] (b) contacting said liquid with an
additive and activated-carbon particles comprising a biogenic
activated carbon composition, [0369] wherein after step (b) at
least a portion of the activated carbon particles comprises the
sulfur contaminant.
[0370] In some embodiments, the sulfur contaminant is selected from
the group consisting of elemental sulfur, sulfuric acid, sulfurous
acid, sulfur dioxide, sulfur trioxide, sulfate anions, bisulfate
anions, sulfite anions, bisulfite anions, thiols, sulfides,
disulfides, polysulfides, thioethers, thioesters, thioacetals,
sulfoxides, sulfones, thiosulfinates, sulfimides, sulfoximides,
sulfonediimines, sulfur halides, thioketones, thioaldehydes, sulfur
oxides, thiocarboxylic acids, thioamides, sulfonic acids, sulfinic
acids, sulfenic acids, sulfonium, oxosulfonium, sulfuranes,
persulfuranes, derivatives thereof, salts thereof and combinations
thereof. In some embodiments, the sulfur contaminant is a sulfate
in anionic and/or salt form. In some embodiments, the additive is
selected from the group consisting of an acid, a base, a salt, a
metal, a metal oxide, a metal hydroxide, a metal halide, iodine, an
iodine compound, and combinations thereof. In some embodiments, the
additive is selected from the group consisting of magnesium,
manganese, aluminum, nickel, iron, chromium, silicon, boron,
cerium, molybdenum, phosphorus, tungsten, vanadium, iron chloride,
iron bromide, magnesium oxide, dolomite, dolomitic lime, fluorite,
fluorospar, bentonite, calcium oxide, lime, sodium hydroxide,
potassium hydroxide, hydrogen bromide, hydrogen chloride, sodium
silicate, potassium permanganate, organic acids, iodine, an iodine
compound, and combinations thereof. In some embodiments, step (b)
comprises filtration and/or osmosis of said liquid. In some
embodiments, step (b) comprises contacting the liquid with an
osmosis membrane comprising said activated-carbon particles and
said additive. In some embodiments, step (b) comprises adding said
activated-carbon particles directly to said liquid. In some
embodiments, the method further comprises: (c) sedimentation of
said activated-carbon particles with said sulfur contaminant from
said liquid. In some embodiments, the liquid comprises wastewater.
In some embodiments, the wastewater is produced by a process
selected from the group consisting of metal mining, acid mine
drainage, mineral processing, municipal sewer treatment, pulp and
paper production, and ethanol production. In some embodiments, the
liquid is a natural body of water.
[0371] In one embodiment, the present disclosure provides a process
to reduce a concentration of sulfates in water comprising: [0372]
(a) providing a volume or stream of water comprising sulfates; and
[0373] (b) contacting said water with an additive and
activated-carbon particles comprising a biogenic activated carbon
composition.
[0374] In some embodiments, before step (a) the water comprises
sulfates at a concentration of greater than about 50 mg/L, and
after step (b) the water comprises sulfates at a concentration of
no more than about 50 mg/L. In some embodiments, after step (b) the
water comprises sulfates at a concentration of no more than about
10 mg/L. In some embodiments, the water is a wastewater stream. In
some embodiments, the wastewater stream is produced by a process
selected from the group consisting of metal mining, acid mine
drainage, mineral processing, municipal sewer treatment, pulp and
paper production, and ethanol production. In some embodiments, the
water is a natural body of water. In some embodiments, the additive
is selected from the group consisting of an acid, a base, a salt, a
metal, a metal oxide, a metal hydroxide, a metal halide, iodine, an
iodine compound, and combinations thereof. In some embodiments, the
additive is selected from the group consisting of magnesium,
manganese, aluminum, nickel, iron, chromium, silicon, boron,
cerium, molybdenum, phosphorus, tungsten, vanadium, iron chloride,
iron bromide, magnesium oxide, dolomite, dolomitic lime, fluorite,
fluorospar, bentonite, calcium oxide, lime, sodium hydroxide,
potassium hydroxide, hydrogen bromide, hydrogen chloride, sodium
silicate, potassium permanganate, organic acids, iodine, an iodine
compound, and combinations thereof.
[0375] In one embodiment, the present disclosure provides a method
of removing a sulfur contaminant from a gas-phase emissions stream
comprising: [0376] (a) providing a gas-phase emissions stream
comprising at least one sulfur contaminant; [0377] (b) contacting
the gas-phase emissions stream with an additive and
activated-carbon particles comprising a biogenic activated carbon
composition; and [0378] (c) separating at least a portion of said
activated-carbon particles from said gas-phase emissions stream
after step (b).
[0379] In some embodiments, the sulfur-containing contaminant is
selected from the group consisting of elemental sulfur, sulfuric
acid, sulfurous acid, sulfur dioxide, sulfur trioxide, sulfate
anions, bisulfate anions, sulfite anions, bisulfate anions, thiols,
sulfides, disulfides, polysulfides, thioethers, thioesters,
thioacetals, sulfoxides, sulfones, thiosulfinates, sulfimides,
sulfoximides, sulfonediimines, sulfur halides, thioketones,
thioaldehydes, sulfur oxides, thiocarboxylic acids, thioamides,
sulfonic acids, sulfinic acids, sulfenic acids, sulfonium,
oxosulfonium, sulfuranes, persulfuranes, salts thereof, derivatives
thereof and combinations thereof. In some embodiments, the
gas-phase emissions stream is derived from, arises out of, or is
produced by combustion of a fuel comprising said biogenic activated
carbon composition. In some embodiments, the gas-phase emissions
stream is derived from, arises out of, or is produced by
co-combustion of coal and said biogenic activated carbon
composition. In some embodiments, the additive is selected from the
group consisting of an acid, a base, a salt, a metal, a metal
oxide, a metal hydroxide, a metal halide, iodine, an iodine
compound, and combinations thereof. In some embodiments, the
additive is selected from the group consisting of magnesium,
manganese, aluminum, nickel, iron, chromium, silicon, boron,
cerium, molybdenum, phosphorus, tungsten, vanadium, iron chloride,
iron bromide, magnesium oxide, dolomite, dolomitic lime, fluorite,
fluorospar, bentonite, calcium oxide, lime, sodium hydroxide,
potassium hydroxide, hydrogen bromide, hydrogen chloride, sodium
silicate, potassium permanganate, organic acids, iodine, an iodine
compound, and combinations thereof. In some embodiments, step (c)
comprises filtration. In some embodiments, step (c) comprises
electrostatic precipitation. In some embodiments, step (c)
comprises scrubbing.
[0380] In one embodiment, the present disclosure provides a method
of reducing or removing one or more contaminants from a gas or
liquid comprising: [0381] (a) providing a gas or liquid stream
containing one or more contaminants; and [0382] (b) contacting said
gas or liquid stream with a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen, and an Iodine Number of at least about 500, wherein
said composition is responsive to an externally applied magnetic
field.
[0383] In one embodiment, the present disclosure provides a method
of reducing or removing one or more contaminants from a gas or
liquid comprising: [0384] (a) providing a gas or liquid stream
containing one or more contaminants; and [0385] (b) contacting said
gas or liquid stream with a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen, and an Iodine Number of at least about 500, wherein
at least a portion of said carbon is present in the form of
graphene.
[0386] In one embodiment, the present disclosure provides a method
of reducing or removing a contaminant from a liquid or gas, said
method comprising: [0387] (a) obtaining a biogenic activated carbon
composition comprising, on a dry basis, about 55 wt % or more total
carbon, about 15 wt % or less hydrogen, and less than or equal to
about 1 wt % nitrogen, wherein at least a portion of said carbon is
present in the form of graphene; [0388] (b) optionally separating
said graphene from said biogenic activated carbon composition; and
[0389] (c) contacting the liquid or gas with said graphene, in
separated form or as part of said biogenic activated carbon
composition.
[0390] In some embodiments, the liquid is water.
[0391] In one embodiment, the present disclosure provides a
composition comprising graphene, wherein the graphene is derived
from a biogenic activated carbon composition comprising, on a dry
basis, about 55 wt % or more total carbon, about 15 wt % or less
hydrogen, and less than or equal to about 1 wt % nitrogen; wherein
at least a portion of said carbon is present in the form of
graphene. In some embodiments, the composition is included in an
adhesive, a sealant, a coating, a paint, an ink, a component of a
composite material, a catalyst, a catalyst support, a battery
electrode component, a fuel cell electrode component, a
graphene-based circuit or memory system component, an energy
storage material, a supercapacitor component, a sink for static
electricity dissipation, a material for electronic or ionic
transport, a high-bandwidth communication system component, a
component of an infrared sensor, a component of a chemical sensor,
a component of a biological sensor, a component of an electronic
display, a component of a voltaic cell, or a graphene aerogel.
[0392] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0393] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0394] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0395] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, in
an adhesive, sealant, coating, paint, or ink.
[0396] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0397] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0398] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0399] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as a
component in a composite material to adjust mechanical or
electrical properties of said composite material.
[0400] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0401] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0402] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0403] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as a
catalyst, a catalyst support, a battery electrode material, or a
fuel cell electrode material.
[0404] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0405] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0406] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0407] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, in a
graphene-based circuit or memory system.
[0408] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0409] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0410] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0411] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as
an energy-storage material or as a supercapacitor component.
[0412] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0413] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0414] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0415] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as a
sink for static electricity dissipation in a liquid or vapor fuel
delivery system.
[0416] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0417] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0418] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0419] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as a
material for electronic or ionic transport.
[0420] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0421] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0422] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0423] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, in a
high-bandwidth communication system.
[0424] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0425] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0426] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0427] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as a
component of an infrared, chemical, or biological sensor.
[0428] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0429] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0430] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0431] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as a
component of an electronic display.
[0432] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0433] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0434] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0435] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, as a
component of a photovoltaic cell.
[0436] In one embodiment, the present disclosure provides a method
of using graphene comprising: [0437] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein at least a portion
of said carbon is present in the form of graphene; [0438] (b)
optionally separating said graphene from said biogenic activated
carbon composition; [0439] (c) using said graphene, in separated
form or as part of said biogenic activated carbon composition, to
form a graphene aerogel.
[0440] In one embodiments provide a method of using a biogenic
activated carbon composition to reduce emissions, the method
comprising: [0441] (a) providing activated-carbon particles
comprising a biogenic activated carbon composition; [0442] (b)
providing a gas-phase emissions stream comprising at least one
selected contaminant; [0443] (c) providing an additive selected to
assist in removal of the selected contaminant from the gas-phase
emissions stream; [0444] (d) introducing the activated-carbon
particles and the additive into the gas-phase emissions stream, to
adsorb at least a portion of the selected contaminant onto the
activated-carbon particles, thereby generating contaminant-adsorbed
carbon particles within the gas-phase emissions stream; and [0445]
(e) separating at least a portion of the contaminant-adsorbed
carbon particles from the gas-phase emissions stream, to produce a
contaminant-reduced gas-phase emissions stream.
[0446] In some embodiments, the biogenic activated carbon
composition comprises 55 wt % or more total carbon; 15 wt % or less
hydrogen; 1 wt % or less nitrogen; 0.5 wt % or less phosphorus; and
0.2 wt % or less sulfur. The additive may be provided as part of
the activated-carbon particles. Alternatively, or additionally, the
additive may be introduced directly into the gas-phase emissions
stream.
[0447] The additive (to assist in removal of the selected
contaminant from the gas-phase emissions stream) may be selected
from an acid, a base, a salt, a metal, a metal oxide, a metal
hydroxide, a metal halide, iodine, an iodine compound, or a
combination thereof. In some embodiments, the additive comprises
iodine or an iodine compound, or a combination of iodine and one or
more iodine compounds, optionally dissolved in a solvent.
[0448] In some embodiments, the selected contaminant is a metal,
such as a metal selected from the group consisting of mercury,
boron, selenium, arsenic, and any compound, salt, and mixture
thereof. In some embodiments, the selected contaminant is a
hazardous air pollutant or a volatile organic compound. In some
embodiments, the selected contaminant is a non-condensable gas
selected from the group consisting of nitrogen oxides, carbon
monoxide, carbon dioxide, hydrogen sulfide, sulfur dioxide, sulfur
trioxide, methane, ethane, ethylene, ozone, ammonia, and
combinations thereof.
[0449] In some embodiments, the contaminant-adsorbed carbon
particles include, in absorbed, adsorbed, or reacted form, at least
one, two, three, or all contaminants selected from the group
consisting of carbon dioxide, nitrogen oxides, mercury, and sulfur
dioxide.
[0450] In some embodiments, the gas-phase emissions stream is
derived from combustion of a fuel comprising the biogenic activated
carbon composition. In certain embodiments, the gas-phase emissions
stream is derived from co-combustion of coal and the biogenic
activated carbon composition.
[0451] In some embodiments, the separating in step (e) comprises
filtration, which may for example utilize fabric filters. In some
embodiments, separating in step (e) comprises electrostatic
precipitation. Scrubbing (including wet or dry scrubbing) may also
be employed. Optionally, the contaminant-adsorbed carbon particles
may be treated to regenerate the activated-carbon particles. In
some embodiments, the contaminant-adsorbed carbon particles are
thermally oxidized catalytically or non-catalytically. The
contaminant-adsorbed carbon particles, or a regenerated form
thereof, may be combusted to provide energy and/or gasified to
provide syngas.
[0452] In some embodiments, a method of using a biogenic activated
carbon composition to reduce mercury emissions, comprises: [0453]
(a) providing activated-carbon particles comprising a biogenic
activated carbon composition that includes an additive comprising
iodine or an iodine-containing compound; [0454] (b) providing a
gas-phase emissions stream comprising mercury; [0455] (c)
introducing the activated-carbon particles into the gas-phase
emissions stream, to adsorb at least a portion of the mercury onto
the activated-carbon particles, thereby generating mercury-adsorbed
carbon particles within the gas-phase emissions stream; and [0456]
(d) separating at least a portion of the mercury-adsorbed carbon
particles from the gas-phase emissions stream using electrostatic
precipitation, to produce a mercury-reduced gas-phase emissions
stream.
[0457] In some variations, a process for energy production is
provided, the process comprising: [0458] (a) providing a
carbon-containing feedstock comprising a biogenic activated carbon
composition; and [0459] (b) oxidizing the carbon-containing
feedstock to generate energy and a gas-phase emissions stream,
[0460] wherein the presence of the biogenic activated carbon
composition within the carbon-containing feedstock is effective to
adsorb at least one contaminant produced as a byproduct of the
oxidizing or derived from the carbon-containing feedstock, thereby
reducing emissions of the contaminant, and [0461] wherein the
biogenic activated carbon composition further includes an additive
that is selected from an acid, a base, a salt, a metal, a metal
oxide, a metal hydroxide, a metal halide, iodine, an iodine
compound, or a combination thereof.
[0462] In some embodiments, the contaminant, or a precursor
thereof, is contained within the carbon-containing feedstock. In
some embodiments, the contaminant is produced as a byproduct of the
oxidizing. The carbon-containing feedstock further comprises
biomass, coal, or another carbonaceous feedstock, in various
embodiments.
[0463] The selected contaminant may be a metal selected from the
group consisting of mercury, boron, selenium, arsenic, and any
compound, salt, and mixture thereof; a hazardous air pollutant; a
volatile organic compound; or a non-condensable gas selected from
the group consisting of nitrogen oxides, carbon monoxide, carbon
dioxide, hydrogen sulfide, sulfur dioxide, sulfur trioxide,
methane, ethane, ethylene, ozone, ammonia; and combinations
thereof.
[0464] In some variations, a method of using a biogenic activated
carbon composition to purify a liquid, comprises: [0465] (a)
providing activated-carbon particles comprising a biogenic
activated carbon composition; [0466] (b) providing a liquid
comprising at least one selected contaminant; [0467] (c) providing
an additive selected to assist in removal of the selected
contaminant from the liquid; and [0468] (d) contacting the liquid
with the activated-carbon particles and the additive, to adsorb at
least a portion of the at least one selected contaminant onto the
activated-carbon particles, thereby generating contaminant-adsorbed
carbon particles and a contaminant-reduced liquid.
[0469] The biogenic activated carbon composition comprises, in some
embodiments, 55 wt % or more total carbon; 15 wt % or less
hydrogen; 1 wt % or less nitrogen; 0.5 wt % or less phosphorus; and
0.2 wt % or less sulfur.
[0470] The additive may be provided as part of the activated-carbon
particles and/or introduced directly into the liquid. The additive
may be selected from an acid, a base, a salt, a metal, a metal
oxide, a metal hydroxide, a metal halide, iodine, an iodine
compound, or a combination thereof.
[0471] In some embodiments, the additive comprises iodine that is
present in the biogenic activated carbon composition as absorbed or
intercalated molecular I.sub.2, physically or chemically adsorbed
molecular I.sub.2, absorbed or intercalated atomic I, physically or
chemically adsorbed atomic I, or a combination thereof.
[0472] In some embodiments, the additive comprises an
iodine-containing compound, such as (but not limited to) an
iodine-containing compound is selected from the group consisting of
iodide ion, hydrogen iodide, an iodide salt, a metal iodide,
ammonium iodide, an iodine oxide, triiodide ion, a triiodide salt,
a metal triiodide, ammonium triiodide, iodate ion, an iodate salt,
a polyiodide, iodoform, iodic acid, methyl iodide, an iodinated
hydrocarbon, periodic acid, orthoperiodic acid, metaperiodic acid,
and combinations, salts, acids, bases, or derivatives thereof.
[0473] Additives may result in a final product with higher energy
content (energy density). An increase in energy content may result
from an increase in total carbon, fixed carbon, volatile carbon, or
even hydrogen. Alternatively or additionally, the increase in
energy content may result from removal of non-combustible matter or
of material having lower energy density than carbon. In some
embodiments, additives reduce the extent of liquid formation, in
favor of solid and gas formation, or in favor of solid
formation.
[0474] In various embodiments, additives chemically modify the
starting biomass, or the treated biomass prior to pyrolysis, to
reduce rupture of cell walls for greater strength/integrity. In
some embodiments, additives may increase fixed carbon content of
biomass feedstock prior to pyrolysis.
[0475] Additives may result in a final biogenic activated carbon
product with improved mechanical properties, such as yield
strength, compressive strength, tensile strength, fatigue strength,
impact strength, elastic modulus, bulk modulus, or shear modulus.
Additives may improve mechanical properties by simply being present
(e.g., the additive itself imparts strength to the mixture) or due
to some transformation that takes place within the additive phase
or within the resulting mixture. For example, reactions such as
vitrification may occur within a portion of the biogenic activated
carbon product that includes the additive, thereby improving the
final strength.
[0476] Chemical additives may be applied to wet or dry biomass
feedstocks. The additives may be applied as a solid powder, a
spray, a mist, a liquid, or a vapor. In some embodiments, additives
may be introduced through spraying of a liquid solution (such as an
aqueous solution or in a solvent), or by soaking in tanks, bins,
bags, or other containers.
[0477] In certain embodiments, dip pretreatment is employed wherein
the solid feedstock is dipped into a bath comprising the additive,
either batchwise or continuously, for a time sufficient to allow
penetration of the additive into the solid feed material.
[0478] In some embodiments, additives applied to the feedstock may
reduce energy requirements for the pyrolysis, and/or increase the
yield of the carbonaceous product. In these or other embodiments,
additives applied to the feedstock may provide functionality that
is desired for the intended use of the carbonaceous product, as
will be further described below regarding compositions.
[0479] In some embodiments, the process for producing a biogenic
activated carbon further comprises a step of sizing (e.g., sorting,
screening, classifying, etc.) the warm or cool pyrolyzed solids to
form sized pyrolyzed solids. The sized pyrolyzed solids can then be
used in applications which call for an activated carbon product
having a certain particle size characteristic.
[0480] The throughput, or process capacity, may vary widely from
small laboratory-scale units to full commercial-scale
biorefineries, including any pilot, demonstration, or
semi-commercial scale. In various embodiments, the process capacity
is at least about 1 kg/day, 10 kg/day, 100 kg/day, 1 ton/day (all
tons are metric tons), 10 tons/day, 100 tons/day, 500 tons/day,
1000 tons/day, 2000 tons/day, or higher.
[0481] In some embodiments, a portion of solids produced may be
recycled to the front end of the process, i.e. to the drying or
deaeration unit or directly to the BPU or reactor. By returning to
the front end and passing through the process again, treated solids
may become higher in fixed carbon. Solid, liquid, and gas streams
produced or existing within the process can be independently
recycled, passed to subsequent steps, or removed/purged from the
process at any point.
[0482] In some embodiments, pyrolyzed material is recovered and
then fed to a separate reactor for further pyrolysis, to create a
product with higher carbon purity. In some embodiments, the
secondary process may be conducted in a simple container, such as a
steel drum, in which heated inert gas (such as heated N.sub.2) is
passed through. Other containers useful for this purpose include
process tanks, barrels, bins, totes, sacks, and roll-offs. This
secondary sweep gas with volatiles may be sent to the process gas
heater, or back to the main BPU, for example. To cool the final
product, another stream of inert gas, which is initially at ambient
temperature for example, may be passed through the solids to cool
the solids, and then returned to an inert gas preheat system. In
various embodiments, the secondary process takes place in a
separate carbonization or pyrolysis reactor, in which preheated
substantially inert gas is inputted to pyrolyze the material and
drive carbonization.
[0483] Some embodiments of the present disclosure provide a
biogenic activated carbon production system comprising: [0484] (a)
a material feed system configured to introduce a carbon-containing
feedstock; [0485] (b) an optional dryer, disposed in operable
communication with the material feed system, configured to remove
moisture contained within a carbon-containing feedstock; [0486] (c)
a biomass processing unit including a plurality of zones, disposed
in operable communication with the dryer, wherein the biomass
processing unit contains at least a pyrolysis zone disposed in
operable communication with a spatially separated cooling zone, and
wherein the biomass processing unit is configured with an outlet to
remove condensable vapors and non-condensable gases from solids;
[0487] (d) an external cooler, disposed in operable communication
with the biomass processing unit; and [0488] (e) a carbon recovery
unit, disposed in operable communication with the cooler.
[0489] Some embodiments of the present disclosure provide a
biogenic activated carbon production system comprising: [0490] (a)
a material feed system configured to introduce a carbon-containing
feedstock; [0491] (b) an optional dryer, disposed in operable
communication with the material feed system, configured to remove
moisture contained within a carbon-containing feedstock; [0492] (c)
an optional preheater, disposed in operable communication with the
dryer, configured to heat and/or mildly pyrolyze the feedstock;
[0493] (d) a pyrolysis reactor, disposed in operable communication
with the preheater, configured to pyrolyze the feedstock; [0494]
(e) a cooler, disposed in operable communication with the pyrolysis
reactor, configured to cool pyrolyzed solids; and [0495] (f) a
carbon recovery unit, disposed in operable communication with the
cooler, [0496] wherein the system is configured with at least one
gas outlet to remove condensable vapors and non-condensable gases
from solids.
[0497] The material feed system may be physically integrated with
the BPU, such as through the use of a screw material feed system or
auger mechanism to introduce feed solids into one of the reactors
or zones.
[0498] In some embodiments, the system further comprises a
preheating zone, disposed in operable communication with the
pyrolysis zone. Each of the pyrolysis zone, cooling zone, and
preheating zone (it present) may be located within a single BPU, or
may be located in separate BPUs.
[0499] Optionally, the dryer may be configured as a drying zone
within the BPU. Optionally, the cooler may be disposed within the
BPU (i.e., configured as an additional cooling zone or integrated
with the cooling zone discussed above).
[0500] The system may include a purging means for removing oxygen
from the system. For example, the purging means may comprise one or
more inlets to introduce a substantially inert gas, and one or more
outlets to remove the substantially inert gas and displaced oxygen
from the system. In some embodiments, the purging means is a
deaerater disposed in operable communication between the dryer and
the BPU.
[0501] The BPU can be configured with at least a first gas inlet
and a first gas outlet. The first gas inlet and the first gas
outlet may be disposed in communication with different zones, or
with the same zones.
[0502] In some embodiments, the BPU is configured with a second gas
inlet and/or a second gas outlet. In some embodiments, the BPU is
configured with a third gas inlet and/or a third gas outlet. In
some embodiments, the BPU is configured with a fourth gas inlet
and/or a fourth gas outlet. In some embodiments, each zone present
in the BPU is configured with a gas inlet and a gas outlet.
[0503] Gas inlets and outlets allow not only introduction and
withdrawal of vapor, but gas outlets (probes) in particular allow
precise process monitoring and control across various stages of the
process, up to and potentially including all stages of the process.
Precise process monitoring would be expected to result in yield and
efficiency improvements, both dynamically as well as over a period
of time when operational history can be utilized to adjust process
conditions.
[0504] In some embodiments (see, generally, FIG. 4), a reaction gas
probe is disposed in operable communication with the pyrolysis
zone. Such a reaction gas probe may be useful to extract gases and
analyze them, in order to determine extent of reaction, pyrolysis
selectivity, or other process monitoring. Then, based on the
measurement, the process may be controlled or adjusted in any
number of ways, such as by adjusting feed rate, rate of inert gas
sweep, temperature (of one or more zones), pressure (of one or more
zones), additives, and so on.
[0505] As intended herein, "monitor and control" via reaction gas
probes should be construed to include any one or more sample
extractions via reaction gas probes, and optionally making process
or equipment adjustments based on the measurements, if deemed
necessary or desirable, using well-known principles of process
control (feedback, feedforward, proportional-integral-derivative
logic, etc.).
[0506] A reaction gas probe may be configured to extract gas
samples in a number of ways. For example, a sampling line may have
a lower pressure than the pyrolysis reactor pressure, so that when
the sampling line is opened an amount of gas can readily be
extracted from pyrolysis zone. The sampling line may be under
vacuum, such as when the pyrolysis zone is near atmospheric
pressure. Typically, a reaction gas probe will be associated with
one gas output, or a portion thereof (e.g., a line split from a gas
output line).
[0507] In some embodiments, both a gas input and a gas output are
utilized as a reaction gas probe by periodically introducing an
inert gas into a zone, and pulling the inert gas with a process
sample out of the gas output ("sample sweep"). Such an arrangement
could be used in a zone that does not otherwise have a gas
inlet/outlet for the substantially inert gas for processing, or,
the reaction gas probe could be associated with a separate gas
inlet/outlet that is in addition to process inlets and outlets. A
sampling inert gas that is introduced and extracted periodically
for sampling (in embodiments that utilize sample sweeps) could even
be different than the process inert gas, if desired, either for
reasons of accuracy in analysis or to introduce an analytical
tracer.
[0508] For example, acetic acid concentration in the gas phase of
the pyrolysis zone may be measured using a gas probe to extract a
sample, which is then analyzed using a suitable technique (such as
gas chromatography, GC; mass spectroscopy, MS; GC-MS, or
Fourier-Transform Infrared Spectroscopy, FTIR). CO and/or CO.sub.2
concentration in the gas phase could be measured and used as an
indication of the pyrolysis selectivity toward gases/vapors, for
example. Terpene concentration in the gas phase could be measured
and used as an indication of the pyrolysis selectivity toward
liquids, and so on.
[0509] In some embodiments, the system further comprises at least
one additional gas probe disposed in operable communication with
the cooling zone, or with the drying zone (if present) or the
preheating zone (if present).
[0510] A gas probe for the cooling zone could be useful to
determine the extent of any additional chemistry taking place in
the cooling zone, for example. A gas probe in the cooling zone
could also be useful as an independent measurement of temperature
(in addition, for example, to a thermocouple disposed in the
cooling zone). This independent measurement may be a correlation of
cooling temperature with a measured amount of a certain species.
The correlation could be separately developed, or could be
established after some period of process operation.
[0511] A gas probe for the drying zone could be useful to determine
the extent of drying, by measuring water content, for example. A
gas probe in the preheating zone could be useful to determine the
extent of any mild pyrolysis taking place, for example.
[0512] In certain embodiments, the cooling zone is configured with
a gas inlet, and the pyrolysis zone is configured with a gas
outlet, to generate substantially countercurrent flow of the gas
phase relative to the solid phase. Alternatively, or additionally,
the preheating zone (when it is present) may be configured with a
gas outlet, to generate substantially countercurrent flow of the
gas phase relative to the solid phase. Alternatively, or
additionally, the drying zone may be configured with a gas outlet,
to generate substantially countercurrent flow.
[0513] The pyrolysis reactor or reactors may be selected from any
suitable reactor configuration that is capable of carrying out the
pyrolysis process. Exemplary reactor configurations include, but
are not limited to, fixed-bed reactors, fluidized-bed reactors,
entrained-flow reactors, augers, rotating cones, rotary drum kilns,
calciners, roasters, moving-bed reactors, transport-bed reactors,
ablative reactors, rotating cones, or microwave-assisted pyrolysis
reactors.
[0514] In some embodiments in which an auger is used, sand or
another heat carrier can optionally be employed. For example, the
feedstock and sand can be fed at one end of a screw. The screw
mixes the sand and feedstock and conveys them through the reactor.
The screw can provide good control of the feedstock residence time
and does not dilute the pyrolyzed products with a carrier or
fluidizing gas. The sand can be reheated in a separate vessel.
[0515] In some embodiments in which an ablative process is used,
the feedstock is moved at a high speed against a hot metal surface.
Ablation of any char forming at surfaces can maintain a high rate
of heat transfer. Such apparatus can prevent dilution of products.
As an alternative, the feedstock particles may be suspended in a
carrier gas and introduced at a high speed through a cyclone whose
wall is heated.
[0516] In some embodiments in which a fluidized-bed reactor is
used, the feedstock can be introduced into a bed of hot sand
fluidized by a gas, which is typically a recirculated product gas.
Reference herein to "sand" shall also include similar,
substantially inert materials, such as glass particles, recovered
ash particles, and the like. High heat-transfer rates from
fluidized sand can result in rapid heating of the feedstock. There
can be some ablation by attrition with the sand particles. Heat is
usually provided by heat-exchanger tubes through which hot
combustion gas flows.
[0517] Circulating fluidized-bed reactors can be employed, wherein
gas, sand, and feedstock move together. Exemplary transport gases
include recirculated product gases and combustion gases. High
heat-transfer rates from the sand ensure rapid heating of the
feedstock, and ablation is expected to be stronger than with
regular fluidized beds. A separator can be employed to separate the
product gases from the sand and char particles. The sand particles
can be reheated in a fluidized burner vessel and recycled to the
reactor.
[0518] In some embodiments, the BPU is a continuous reactor
comprising a feedstock inlet, a plurality of spatially separated
zones configured for separately controlling the temperature and
mixing within each of the zones, and a carbonaceous-solids outlet,
wherein one of the zones is configured with a first gas inlet for
introducing a substantially inert gas into the BPU, and wherein one
of the zones is configured with a first gas outlet.
[0519] In some embodiments the reactor includes at least two,
three, four, or more zones. Each of the zones is disposed in
communication with separately adjustable heating means
independently selected from the group consisting of electrical heat
transfer, steam heat transfer, hot-oil heat transfer, phase-change
heat transfer, waste heat transfer, and combinations thereof. In
some embodiments, at least one zone is heated with an effluent
stream from the process gas heater, if present.
[0520] The BPU may be configured for separately adjusting gas-phase
composition and gas-phase residence time of at least two zones, up
to and including all zones present in the BPU.
[0521] The BPU may be equipped with a second gas inlet and/or a
second gas outlet. In some embodiments, the BPU is configured with
a gas inlet in each zone. In these or other embodiments, the BPU is
configured with a gas outlet in each zone. The BPU may be a
cocurrent or countercurrent reactor.
[0522] In some embodiments, the material feed system comprises a
screw or auger feed mechanism. In some embodiments, the
carbonaceous-solids outlet comprises a screw or auger output
mechanism.
[0523] Some embodiments utilize a rotating calciner with a screw
material feed system. In these embodiments, some or all of the BPU
is axially rotatable, i.e. it spins about its centerline axis. The
speed of rotation will impact the solid flow pattern, and heat and
mass transport. Each of the zones may be configured with flights
disposed on internal walls, to provide agitation of solids. The
flights may be separately adjustable in each of the zones.
[0524] Other means of agitating solids may be employed, such as
augers, screws, or paddle conveyors. In some embodiments, the BPU
includes a single, continuous auger disposed throughout each of the
zones. In other embodiments, the reactor includes twin screws
disposed throughout each of the zones.
[0525] Some systems are designed specifically with the capability
to maintain the approximate size of feed material throughout the
process--that is, to process the biomass feedstock without
destroying or significantly damaging its structure. In some
embodiments, the pyrolysis zone does not contain augers, screws, or
rakes that would tend to greatly reduce the size of feed material
being pyrolyzed.
[0526] In some embodiments of the disclosure, the system further
includes a process gas heater disposed in operable communication
with the outlet at which condensable vapors and non-condensable
gases are removed. The process gas heater can be configured to
receive a separate fuel (such as natural gas) and an oxidant (such
as air) into a combustion chamber, adapted for combustion of the
fuel and at least a portion of the condensable vapors. Certain
non-condensable gases may also be oxidized, such as CO or CH.sub.4,
to CO.sub.2.
[0527] When a process gas heater is employed, the system may
include a heat exchanger disposed between the process gas heater
and the dryer, configured to utilize at least some of the heat of
the combustion for the dryer. This embodiment can contribute
significantly to the overall energy efficiency of the process.
[0528] In some embodiments, the system further comprises a material
enrichment unit, disposed in operable communication with the
cooler, configured for combining condensable vapors, in at least
partially condensed form, with the solids. The material enrichment
unit may increase the carbon content of the biogenic activated
carbon obtained from the carbon recovery unit.
[0529] The system may further include a separate pyrolysis zone
adapted to further pyrolyze the biogenic activated carbon to
further increase its carbon content. The separate pyrolysis zone
may be a relatively simply container, unit, or device, such as a
tank, barrel, bin, drum, tote, sack, or roll-off.
[0530] The overall system may be at a fixed location, or it may be
made portable. The system may be constructed using modules which
may be simply duplicated for practical scale-up. The system may
also be constructed using economy-of-scale principles, as is
well-known in the process industries.
[0531] Some embodiments of the present disclosure relating to
carbon enrichment of solids will now be further described. In some
embodiments, a process for producing a biogenic activated carbon
comprises: [0532] (a) providing a carbon-containing feedstock
comprising biomass; [0533] (b) optionally drying the feedstock to
remove at least a portion of moisture contained within the
feedstock; [0534] (c) optionally deaerating the feedstock to remove
at least a portion of interstitial oxygen, if any, contained with
the feedstock; [0535] (d) in a pyrolysis zone, pyrolyzing the
feedstock in the presence of a substantially inert gas for at least
10 minutes and with a pyrolysis temperature selected from about
250.degree. C. to about 700.degree. C., to generate hot pyrolyzed
solids, condensable vapors, and non-condensable gases; [0536] (e)
separating at least a portion of the condensable vapors and at
least a portion of the non-condensable gases from the hot pyrolyzed
solids; [0537] (f) in a cooling zone, cooling the hot pyrolyzed
solids, in the presence of the substantially inert gas for at least
5 minutes and with a cooling temperature less than or equal to
about the pyrolysis temperature, to generate warm pyrolyzed solids;
[0538] (g) optionally cooling the warm pyrolyzed solids in a cooler
to generate cool pyrolyzed solids; [0539] (h) subsequently passing
at least a portion of the condensable vapors and/or at least a
portion of the non-condensable gases from step (e) across the warm
pyrolyzed solids and/or the cool pyrolyzed solids, to form enriched
pyrolyzed solids with increased carbon content; and [0540] (i) in a
carbon recovery unit, recovering a biogenic activated carbon
comprising at least a portion of the enriched pyrolyzed solids.
[0541] In some embodiments, step (h) includes passing at least a
portion of the condensable vapors from step (e), in vapor and/or
condensed form, across the warm pyrolyzed solids, to produce
enriched pyrolyzed solids with increased carbon content. In some
embodiments, step (h) includes passing at least a portion of the
non-condensable gases from step (e) across the warm pyrolyzed
solids, to produce enriched pyrolyzed solids with increased carbon
content.
[0542] It should be appreciated that in various embodiments, carbon
enrichment increases carbon content, energy content, as well as
mass yield.
[0543] Alternatively, or additionally, vapors or gases may be
contacted with the cool pyrolyzed solids. In some embodiments, step
(h) includes passing at least a portion of the condensable vapors
from step (e), in vapor and/or condensed form, across the cool
pyrolyzed solids, to produce enriched pyrolyzed solids with
increased carbon content. In some embodiments, step (h) includes
passing at least a portion of the non-condensable gases from step
(e) across the cool pyrolyzed solids, to produce enriched pyrolyzed
solids with increased carbon content.
[0544] In certain embodiments, step (h) includes passing
substantially all of the condensable vapors from step (e), in vapor
and/or condensed form, across the cool pyrolyzed solids, to produce
enriched pyrolyzed solids with increased carbon content. In certain
embodiments, step (h) includes passing substantially all of the
non-condensable gases from step (e) across the cool pyrolyzed
solids, to produce enriched pyrolyzed solids with increased carbon
content.
[0545] The process may include various methods of treating or
separating the vapors or gases prior to using them for carbon
enrichment. For example, an intermediate feed stream consisting of
at least a portion of the condensable vapors and at least a portion
of the non-condensable gases, obtained from step (e), may be fed to
a separation unit configured to generate at least first and second
output streams. In certain embodiments, the intermediate feed
stream comprises all of the condensable vapors, all of the
non-condensable gases, or both.
[0546] Separation techniques can include or use distillation
columns, flash vessels, centrifuges, cyclones, membranes, filters,
packed beds, capillary columns, and so on. Separation can be
principally based, for example, on distillation, absorption,
adsorption, or diffusion, and can utilize differences in vapor
pressure, activity, molecular weight, density, viscosity, polarity,
chemical functionality, affinity to a stationary phase, and any
combinations thereof.
[0547] In some embodiments, the first and second output streams are
separated from the intermediate feed stream based on relative
volatility. For example, the separation unit may be a distillation
column, a flash tank, or a condenser.
[0548] Thus in some embodiments, the first output stream comprises
the condensable vapors, and the second output stream comprises the
non-condensable gases. The condensable vapors may include at least
one carbon-containing compound selected from terpenes, alcohols,
acids, aldehydes, or ketones. The vapors from pyrolysis may include
aromatic compounds such as benzene, toluene, ethylbenzene, and
xylenes. Heavier aromatic compounds, such as refractory tars, may
be present in the vapor. The non-condensable gases may include at
least one carbon-containing molecule selected from the group
consisting of carbon monoxide, carbon dioxide, and methane.
[0549] In some embodiments, the first and second output streams are
separated intermediate feed stream based on relative polarity. For
example, the separation unit may be a stripping column, a packed
bed, a chromatography column, or membranes.
[0550] Thus in some embodiments, the first output stream comprises
polar compounds, and the second output stream comprises non-polar
compounds. The polar compounds may include at least one
carbon-containing molecule selected from the group consisting of
methanol, furfural, and acetic acid. The non-polar compounds may
include at least one carbon-containing molecule selected from the
group consisting of carbon monoxide, carbon dioxide, methane, a
terpene, and a terpene derivative.
[0551] Step (h) may increase the total carbon content of the
biogenic activated carbon, relative to an otherwise-identical
process without step (h). The extent of increase in carbon content
may be, for example, about 1%, 2%, 5%, 10%, 15%, 25%, or even
higher, in various embodiments.
[0552] In some embodiments, step (h) increases the fixed carbon
content of the biogenic activated carbon. In these or other
embodiments, step (h) increases the volatile carbon content of the
biogenic activated carbon. Volatile carbon content is the carbon
attributed to volatile matter in the reagent. The volatile matter
may be, but is not limited to, hydrocarbons including aliphatic or
aromatic compounds (e.g., terpenes); oxygenates including alcohols,
aldehydes, or ketones; and various tars. Volatile carbon will
typically remain bound or adsorbed to the solids at ambient
conditions but upon heating, will be released before the fixed
carbon would be oxidized, gasified, or otherwise released as a
vapor.
[0553] Depending on conditions associated with step (h), it is
possible for some amount of volatile carbon to become fixed carbon
(e.g., via Boudouard carbon formation from CO). Typically, the
volatile matter will be expected to enter the micropores of the
fixed carbon and will be present as condensed/adsorbed species, but
still relatively volatile. This residual volatility can be more
advantageous for fuel applications, compared to product
applications requiring high surface area and porosity.
[0554] Step (h) may increase the energy content (i.e., energy
density) of the biogenic activated carbon. The increase in energy
content may result from an increase in total carbon, fixed carbon,
volatile carbon, or even hydrogen. The extent of increase in energy
content may be, for example, about 1%, 2%, 5%, 10%, 15%, 25%, or
even higher, in various embodiments.
[0555] Further separations may be employed to recover one or more
non-condensable gases or condensable vapors, for use within the
process or further processing. For example, further processing may
be included to produce refined CO or syngas.
[0556] As another example, separation of acetic acid may be
conducted, followed by reduction of the acetic acid into ethanol.
The reduction of the acetic acid may be accomplished, at least in
part, using hydrogen derived from the non-condensable gases
produced.
[0557] Condensable vapors may be used for either energy in the
process (such as by thermal oxidation) or in carbon enrichment, to
increase the carbon content of the biogenic activated carbon.
Certain non-condensable gases, such as CO or CH.sub.4, may be
utilized either for energy in the process, or as part of the
substantially inert gas for the pyrolysis step. Combinations of any
of the foregoing are also possible.
[0558] A potential benefit of including step (h) is that the gas
stream is scrubbed, with the resulting gas stream being enriched in
CO and CO.sub.2. The resulting gas stream may be utilized for
energy recovery, recycled for carbon enrichment of solids, and/or
used as an inert gas in the reactor. Similarly, by separating
non-condensable gases from condensable vapors, the CO/CO.sub.2
stream is prepared for use as the inert gas in the reactor system
or in the cooling system, for example.
[0559] Other variations of the disclosure are premised on the
realization that the principles of the carbon-enrichment step may
be applied to any feedstock in which it is desired to add
carbon.
[0560] In some embodiments, a batch or continuous process for
producing a biogenic activated carbon comprises: [0561] (a)
providing a solid stream comprising a carbon-containing material;
[0562] (b) providing a gas stream comprising condensable
carbon-containing vapors, non-condensable carbon-containing gases,
or a mixture of condensable carbon-containing vapors and
non-condensable carbon-containing gases; and [0563] (c) passing the
gas stream across the solid stream under suitable conditions to
form a carbon-containing product with increased carbon content
relative to the carbon-containing material.
[0564] In some embodiments, the starting carbon-containing material
is pyrolyzed biomass or torrefied biomass. The gas stream may be
obtained during an integrated process that provides the
carbon-containing material. Or, the gas stream may be obtained from
separate processing of the carbon-containing material. The gas
stream, or a portion thereof, may be obtained from an external
source (e.g., an oven at a lumber mill). Mixtures of gas streams,
as well as mixtures of carbon-containing materials, from a variety
of sources, are possible.
[0565] In some embodiments, the process further comprises recycling
or reusing the gas stream for repeating the process to further
increase carbon and/or energy content of the carbon-containing
product. In some embodiments, the process further comprises
recycling or reusing the gas stream for carrying out the process to
increase carbon and/or energy content of another feedstock
different from the carbon-containing material.
[0566] In some embodiments, the process further includes
introducing the gas stream to a separation unit configured to
generate at least first and second output streams, wherein the gas
stream comprises a mixture of condensable carbon-containing vapors
and non-condensable carbon-containing gases. The first and second
output streams may be separated based on relative volatility,
relative polarity, or any other property. The gas stream may be
obtained from separate processing of the carbon-containing
material.
[0567] In some embodiments, the process further comprises recycling
or reusing the gas stream for repeating the process to further
increase carbon content of the carbon-containing product. In some
embodiments, the process further comprises recycling or reusing the
gas stream for carrying out the process to increase carbon content
of another feedstock.
[0568] The carbon-containing product may have an increased total
carbon content, a higher fixed carbon content, a higher volatile
carbon content, a higher energy content, or any combination
thereof, relative to the starting carbon-containing material.
[0569] In related variations, a biogenic activated carbon
production system comprises: [0570] (a) a material feed system
configured to introduce a carbon-containing feedstock; [0571] (b)
an optional dryer, disposed in operable communication with the
material feed system, configured to remove moisture contained
within a carbon-containing feedstock; [0572] (c) a BPU, disposed in
operable communication with the dryer, wherein the BPU contains at
least a pyrolysis zone disposed in operable communication with a
spatially separated cooling zone, and wherein the BPU is configured
with an outlet to remove condensable vapors and non-condensable
gases from solids; [0573] (d) a cooler, disposed in operable
communication with the BPU; [0574] (e) a material enrichment unit,
disposed in operable communication with the cooler, configured to
pass the condensable vapors and/or the non-condensable gases across
the solids, to form enriched solids with increased carbon content;
and [0575] (f) a carbon recovery unit, disposed in operable
communication with the material enrichment unit.
[0576] The system may further comprise a preheating zone, disposed
in operable communication with the pyrolysis zone. In some
embodiments, the dryer is configured as a drying zone within the
BPU. Each of the zones may be located within a single BPU or in
separate BPUs. Also, the cooler may be disposed within the BPU.
[0577] In some embodiments, the cooling zone is configured with a
gas inlet, and the pyrolysis zone is configured with a gas outlet,
to generate substantially countercurrent flow of the gas phase
relative to the solid phase. In these or other embodiments, the
preheating zone and/or the drying zone (or dryer) is configured
with a gas outlet, to generate substantially countercurrent flow of
the gas phase relative to the solid phase.
[0578] In particular embodiments, the system incorporates a
material enrichment unit that comprises: [0579] (i) a housing with
an upper portion and a lower portion; [0580] (ii) an inlet at a
bottom of the lower portion of the housing configured to carry the
condensable vapors and non-condensable gases; [0581] (iii) an
outlet at a top of the upper portion of the housing configured to
carry
[0582] a concentrated gas stream derived from the condensable
vapors and non-condensable gases; [0583] (iv) a path defined
between the upper portion and the lower portion of the housing; and
[0584] (v) a material transport system following the path, the
material transport system configured to transport the solids,
wherein the housing is shaped such that the solids adsorb at least
some of the condensable vapors and/or at least some of the
non-condensable gases.
[0585] The present disclosure is capable of producing a variety of
compositions useful as biogenic activated carbons, and products
incorporating these reagents. In some variations, a biogenic
activated carbon is produced by any process disclosed herein, such
as a process comprising the steps of: [0586] (a) providing a
carbon-containing feedstock comprising biomass; [0587] (b)
optionally drying the feedstock to remove at least a portion of
moisture contained within the feedstock; [0588] (c) optionally
deaerating the feedstock to remove at least a portion of
interstitial oxygen, if any, contained with the feedstock; [0589]
(d) in a pyrolysis zone, pyrolyzing the feedstock in the presence
of a substantially inert gas for at least 10 minutes and with a
pyrolysis temperature selected from about 250.degree. C. to about
700.degree. C., to generate hot pyrolyzed solids, condensable
vapors, and non-condensable gases; [0590] (e) separating at least a
portion of the condensable vapors and at least a portion of the
non-condensable gases from the hot pyrolyzed solids; [0591] (f) in
a cooling zone, cooling the hot pyrolyzed solids, in the presence
of the substantially inert gas for at least 5 minutes and with a
cooling temperature less than or equal to about the pyrolysis
temperature, to generate warm pyrolyzed solids; [0592] (g) cooling
the warm pyrolyzed solids to generate cool pyrolyzed solids; and
[0593] (h) recovering a biogenic activated carbon comprising at
least a portion of the cool pyrolyzed solids.
[0594] In some embodiments, the process for producing a biogenic
activated carbon further comprises a step of sizing (e.g., sorting,
screening, classifying, etc.) the warm or cool pyrolyzed solids to
form sized pyrolyzed solids. The sized pyrolyzed solids can then be
used in applications which call for an activated carbon product
having a certain particle size characteristic.
[0595] In some embodiments, the biogenic activated carbon comprises
at least about 55 wt. %, for example at least 55 wt. %, at least 60
wt. %, at least 65 wt. %, at least 70 wt %, at least 75 wt. %, at
least 80 wt %, at least 85 wt. %, at least 90 wt %, at least 95 wt
%, at least 96 wt %, at least 97 wt %, at least 98 wt %, or at
least 99 wt % total carbon on a dry basis. The total carbon
includes at least fixed carbon, and may further include carbon from
volatile matter. In some embodiments, carbon from volatile matter
is about at least 5%, at least 10%, at least 25%, or at least 50%
of the total carbon present in the biogenic activated carbon. Fixed
carbon may be measured using ASTM D3172, while volatile carbon may
be estimated using ASTM D3175, for example.
[0596] Biogenic activated carbon according to the present
disclosure may comprise about 0 wt % to about 8 wt % hydrogen. In
some embodiments, biogenic activated carbon comprises greater than
about 0.5 wt % hydrogen, for example about 0.6 wt %, about 0.7 wt
%, about 0.8 wt %, about 0.9 wt %, about 1 wt %, about 1.2 wt %,
about 1.4 wt %, about 1.6 wt %, about 1.8 wt %, about 2 wt %, about
2.2 wt %, about 2.4 wt %, about 2.6 wt %, about 2.8 wt %, about 3
wt %, about 3.2 wt %, about 3.4 wt %, about 3.6 wt %, about 3.8 wt
%, about 4 wt %, or greater than about 4 wt % hydrogen. The
hydrogen content of biogenic activated carbon may be determined by
any suitable method known in the art, for example by the combustion
analysis procedure outlined in ASTM D5373. In some embodiments,
biogenic activated carbon has a hydrogen content that is greater
than the hydrogen content of activated carbon derived from fossil
fuel sources. Typically, fossil fuel based activated carbon
products have less than or equal to about 1 wt % hydrogen, for
example about 0.6 wt % hydrogen. In some embodiments, the
characteristics of an activated carbon product can be optimized by
blending an amount of a fossil fuel based activated carbon product
(i.e., with a very low hydrogen content) with a suitable amount of
a biogenic activated carbon product having a hydrogen content
greater than that of the fossil fuel based activated carbon
product.
[0597] The biogenic activated carbon may comprise about 10 wt % or
less, such as about 5 wt % or less, hydrogen on a dry basis. The
biogenic activated carbon product may comprise about 1 wt % or
less, such as about 0.5 wt % or less, nitrogen on a dry basis. The
biogenic activated carbon product may comprise about 0.5 wt % or
less, such as about 0.2 wt % or less, phosphorus on a dry basis.
The biogenic activated carbon product may comprise about 0.2 wt %
or less, such as about 0.1 wt % or less, sulfur on a dry basis.
[0598] In certain embodiments, the biogenic activated carbon
includes oxygen, such as up to 20 wt % oxygen, for example about
0.2 wt %, about 0.5 wt %, about 1 wt %, about 2 wt %, about 3 wt %,
about 4 wt %, about 5 wt %, about 6 wt %, about 7 wt %, about 7.5
wt %, about 8 wt %, about 9 wt %, about 10 wt %, about 11 wt %,
about 12 wt %, about 13 wt %, about 14 wt %, about 15 wt %, about
16 wt %, about 17 wt %, about 18 wt %, about 19 wt %, or about 20
wt % oxygen. The presence of oxygen may be beneficial in the
activated carbon for certain applications, such as mercury capture,
especially in conjunction with the presence of a halogen (such as
chlorine or bromine) In some embodiments, biogenic activated carbon
has a oxygen content that is greater than the oxygen content of
activated carbon derived from fossil fuel sources. Typically,
fossil fuel based activated carbon products have less than or equal
to about 10 wt % oxygen, for example about 7 wt % oxygen or about
0.3 wt % oxygen. In some embodiments, the characteristics of an
activated carbon product can be optimized by blending an amount of
a fossil fuel based activated carbon product (i.e., with a very low
oxygen content) with a suitable amount of a biogenic activated
carbon product having a oxygen content greater than that of the
fossil fuel based activated carbon product.
[0599] Carbon, hydrogen, and nitrogen may be measured using ASTM
D5373 for ultimate analysis, for example. Oxygen may be estimated
using ASTM D3176, for example. Sulfur may be measured using ASTM
D3177, for example.
[0600] Certain embodiments provide reagents with little or
essentially no hydrogen (except from any moisture that may be
present), nitrogen, phosphorus, or sulfur, and are substantially
carbon plus any ash and moisture present. Therefore, some
embodiments provide a material with up to and including 100%
carbon, on a dry/ash-free (DAF) basis.
[0601] Generally speaking, feedstocks such as biomass contain
non-volatile species, including silica and various metals, which
are not readily released during pyrolysis. It is of course possible
to utilize ash-free feedstocks, in which case there should not be
substantial quantities of ash in the pyrolyzed solids. Ash may be
measured using ASTM D3174, for example.
[0602] Various amounts of non-combustible matter, such as ash, may
be present. The biogenic activated carbon may comprise about 10 wt
% or less, such as about 5 wt %, about 2 wt %, about 1 wt % or less
than or equal to about 1 wt % of non-combustible matter on a dry
basis. In certain embodiments, the reagent contains little ash, or
even essentially no ash or other non-combustible matter. Therefore,
some embodiments provide essentially pure carbon, including 100%
carbon, on a dry basis.
[0603] Various amounts of moisture may be present. On a total mass
basis, the biogenic activated carbon may comprise at least 1 wt %,
at least 2 wt %, at least 5 wt %, at least 10 wt %, at least 15 wt
%, at least 25 wt %, at least 35 wt %, at least 50 wt %, or more
than 50 wt % of moisture. As intended herein, "moisture" is to be
construed as including any form of water present in the biogenic
activated carbon product, including absorbed moisture, adsorbed
water molecules, chemical hydrates, and physical hydrates. The
equilibrium moisture content may vary at least with the local
environment, such as the relative humidity. Also, moisture may vary
during transportation, preparation for use, and other logistics.
Moisture may be measured by any suitable method known in the art,
including ASTM D3173, for example.
[0604] The biogenic activated carbon may have various "energy
content" which for present purposes means the energy density based
on the higher heating value associated with total combustion of the
bone-dry reagent. For example, the biogenic activated carbon may
possess an energy content of about at least 11,000 Btu/lb, at least
12,000 Btu/lb, at least 13,000 Btu/lb, at least 14,000 Btu/lb, or
at least 15,000 Btu/lb. In certain embodiments, the energy content
is between about 14,000-15,000 Btu/lb. The energy content may be
measured by any suitable method known in the art, including ASTM
D5865, for example.
[0605] The biogenic activated carbon may be formed into a powder,
such as a coarse powder or a fine powder. For example, the reagent
may be formed into a powder with an average mesh size of about 200
mesh, about 100 mesh, about 50 mesh, about 10 mesh, about 6 mesh,
about 4 mesh, or about 2 mesh, in embodiments. In some embodiments,
the biogenic activated carbon has an average particle size of up to
about 500 .mu.m, for example less than or equal to about 10 .mu.m,
about 10 .mu.m, about 25 .mu.m, about 50 about 75 .mu.m, about 100
.mu.m, about 200 about 300 about 400 or about 500 .mu.m.
[0606] The biogenic activated carbon may be produced as powder
activated carbon, which generally includes particles with a size
predominantly less than or equal to about 0.21 mm (70 mesh). The
biogenic activated carbon may be produced as granular activated
carbon, which generally includes irregularly shaped particles with
sizes ranging from 0.2 mm to 5 mm. The biogenic activated carbon
may be produced as pelletized activated carbon, which generally
includes extruded and cylindrically shaped objects with diameters
from 0.8 mm to 5 mm.
[0607] In some embodiments, the biogenic activated carbon is formed
into structural objects comprising pressed, binded, or agglomerated
particles. The starting material to form these objects may be a
powder form of the reagent, such as an intermediate obtained by
particle-size reduction. The objects may be formed by mechanical
pressing or other forces, optionally with a binder or other means
of agglomerating particles together.
[0608] Following formation from pyrolysis, the biogenic activated
carbon may be pulverized to form a powder. "Pulverization" in this
context is meant to include any sizing, milling, pulverizing,
grinding, crushing, extruding, or other primarily mechanical
treatment to reduce the average particle size. The mechanical
treatment may be assisted by chemical or electrical forces, if
desired. Pulverization may be a batch, continuous, or
semi-continuous process and may be carried out at a different
location than that of formation of the pyrolyzed solids, in some
embodiments.
[0609] In some embodiments, the biogenic activated carbon is
produced in the form of structural objects whose structure
substantially derives from the feedstock. For example, feedstock
chips may produce product chips of biogenic activated carbon. Or,
feedstock cylinders may produce biogenic activated carbon
cylinders, which may be somewhat smaller but otherwise maintain the
basic structure and geometry of the starting material.
[0610] A biogenic activated carbon according to the present
disclosure may be produced as, or formed into, an object that has a
minimum dimension of at least about 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6
cm, 7 cm, 8 cm, 9 cm, 10 cm, or higher. In various embodiments, the
minimum dimension or maximum dimension can be a length, width, or
diameter.
[0611] Other variations of the disclosure relate to the
incorporation of additives into the process, into the product, or
both. In some embodiments, the biogenic activated carbon includes
at least one process additive incorporated during the process. In
these or other embodiments, the activated carbon includes at least
one product additive introduced to the activated carbon following
the process.
[0612] Other variations of the disclosure relate to the
incorporation of additives into the process, into the product, or
both. In some embodiments, the biogenic activated carbon includes
at least one process additive incorporated during the process. In
these or other embodiments, the reagent includes at least one
product additive introduced to the reagent following the
process.
[0613] In some embodiments, a biogenic activated carbon comprises,
on a dry basis:
[0614] 55 wt % or more total carbon;
[0615] 5 wt % or less hydrogen;
[0616] 1 wt % or less nitrogen;
[0617] optionally from 0.5 wt % to 10 wt % oxygen;
[0618] 0.5 wt % or less phosphorus;
[0619] 0.2 wt % or less sulfur; and [0620] an additive selected
from a metal, a metal oxide, a metal hydroxide, a metal halide, or
a combination thereof
[0621] The additive may be selected from, but is by no means
limited to, iron chloride, iron bromide, magnesium, manganese,
aluminum, nickel, chromium, silicon, magnesium oxide, dolomite,
dolomitic lime, fluorite, fluorospar, bentonite, calcium oxide,
lime, or combinations thereof.
[0622] In some embodiments, a biogenic activated carbon comprises,
on a dry basis:
[0623] 55 wt % or more total carbon;
[0624] 5 wt % or less hydrogen;
[0625] 1 wt % or less nitrogen;
[0626] optionally from 0.5 wt % to 10 wt % oxygen;
[0627] 0.5 wt % or less phosphorus;
[0628] 0.2 wt % or less sulfur; and [0629] an additive selected
from an acid, a base, or a salt thereof
[0630] The additive may be selected from, but is by no means
limited to, sodium hydroxide, potassium hydroxide, magnesium oxide,
hydrogen bromide, hydrogen chloride, sodium silicate, potassium
permanganate, organic acids (e.g., citric acid), or combinations
thereof.
[0631] In certain embodiments, a biogenic activated carbon
comprises, on a dry basis:
[0632] 55 wt % or more total carbon;
[0633] 5 wt % or less hydrogen;
[0634] 1 wt % or less nitrogen;
[0635] optionally from 0.5 wt % to 10 wt % oxygen;
[0636] 0.5 wt % or less phosphorus;
[0637] 0.2 wt % or less sulfur; [0638] a first additive selected
from a metal, metal oxide, metal hydroxide, a metal halide, or a
combination thereof; and [0639] a second additive selected from an
acid, a base, or a salt thereof, [0640] wherein the first additive
is different from the second additive.
[0641] The first additive may be selected from iron chloride, iron
bromide, magnesium, manganese, aluminum, nickel, chromium, silicon,
magnesium oxide, dolomite, dolomitic lime, fluorite, fluorospar,
bentonite, calcium oxide, lime, or combinations thereof, while the
second additive may be independently selected from sodium
hydroxide, potassium hydroxide, magnesium oxide, hydrogen bromide,
hydrogen chloride, sodium silicate, potassium permanganate, organic
acids (e.g., citric acid), or combinations thereof.
[0642] A certain biogenic activated carbon consists essentially of,
on a dry basis, carbon, hydrogen, nitrogen, oxygen, phosphorus,
sulfur, non-combustible matter, and an additive selected from the
group consisting of iron chloride, iron bromide, magnesium,
manganese, aluminum, nickel, chromium, silicon, magnesium oxide,
dolomite, dolomitic lime, fluorite, fluorospar, bentonite, calcium
oxide, lime, and combinations thereof.
[0643] A certain biogenic activated carbon consists essentially of,
on a dry basis, carbon, hydrogen, nitrogen, oxygen, phosphorus,
sulfur, non-combustible matter, and an additive selected from the
group consisting of sodium hydroxide, potassium hydroxide,
magnesium oxide, hydrogen bromide, hydrogen chloride, sodium
silicate, and combinations thereof.
[0644] The amount of additive (or total additives) may vary widely,
such as from about 0.01 wt % to about 25 wt %, including about 0.1
wt %, about 1 wt %, about 5 wt %, about 10 wt %, or about 20 wt %
on a dry basis. It will be appreciated then when relatively large
amounts of additives are incorporated, such as higher than about 1
wt %, there will be a reduction in energy content calculated on the
basis of the total activated carbon weight (inclusive of
additives). Still, in various embodiments, the biogenic activated
carbon with additive(s) may possess an energy content of about at
least 11,000 Btu/lb, at least 12,000 Btu/lb, at least 13,000
Btu/lb, at least 14,000 Btu/lb, or at least 15,000 Btu/lb, when
based on the entire weight of the biogenic activated carbon
(including the additive(s)).
[0645] The above discussion regarding product form applies also to
embodiments that incorporate additives. In fact, certain
embodiments incorporate additives as binders or other modifiers to
enhance final properties for a particular application.
[0646] In some embodiments, the majority of carbon contained in the
biogenic activated carbon is classified as renewable carbon. In
some embodiments, substantially all of the carbon is classified as
renewable carbon. There may be certain market mechanisms (e.g.,
Renewable Identification Numbers, tax credits, etc.) wherein value
is attributed to the renewable carbon content within the biogenic
activated carbon. In some embodiments, the additive itself is
derived from biogenic sources or is otherwise classified as derived
from a renewable carbon source. For example, some organic acids
such as citric acid are derived from renewable carbon sources.
Thus, in some embodiments, the carbon content of a biogenic
activated carbon consists of, consists essentially of, or consists
substantially of renewable carbon. For example, a fully biogenic
activated carbon formed by methods as disclosed herein consist of,
consist essentially of, or consist substantially of (a) pyrolyzed
solids derived solely from biomass from renewable carbon sources
and (b) one or more additives derived solely from renewable carbon
sources
[0647] The biogenic activated carbon produced as described herein
is useful for a wide variety of carbonaceous products. In
variations, a product includes any of the biogenic activated
carbons that may be obtained by the disclosed processes, or that
are described in the compositions set forth herein, or any
portions, combinations, or derivatives thereof.
[0648] Generally speaking, the biogenic activated carbons may be
combusted to produce energy (including electricity and heat);
partially oxidized or steam-reformed to produce syngas; utilized
for their adsorptive or absorptive properties; utilized for their
reactive properties during metal refining (such as reduction of
metal oxides) or other industrial processing; or utilized for their
material properties in carbon steel and various other metal alloys.
Essentially, the biogenic activated carbons may be utilized for any
market application of carbon-based commodities or advanced
materials, including specialty uses to be developed.
[0649] Biogenic activated carbon prepared according to the
processes disclosed herein has the same or better characteristics
as traditional fossil fuel-based activated carbon. In some
embodiments, biogenic activated carbon has a surface area that is
comparable to, equal to, or greater than surface area associated
with fossil fuel-based activated carbon. In some embodiments,
biogenic activated carbon can control pollutants as well as or
better than traditional activated carbon products. In some
embodiments, biogenic activated carbon has an inert material (e.g.,
ash) level that is comparable to, equal to, or less than or equal
to about an inert material (e.g., ash) level associated with a
traditional activated carbon product. In some embodiments, biogenic
activated carbon has a particle size and/or a particle size
distribution that is comparable to, equal to, greater than, or less
than or equal to about a particle size and/or a particle size
distribution associated with a traditional activated carbon
product. In some embodiments, a biogenic activated carbon product
has a particle shape that is comparable to, substantially similar
to, or the same as a particle shape associated with a traditional
activated carbon product. In some embodiments, a biogenic activated
carbon product has a particle shape that is substantially different
than a particle shape associated with a traditional activated
carbon product. In some embodiments, a biogenic activated carbon
product has a pore volume that is comparable to, equal to, or
greater than a pore volume associated with a traditional activated
carbon product. In some embodiments, a biogenic activated carbon
product has pore dimensions that are comparable to, substantially
similar to, or the same as pore dimensions associated with a
traditional activated carbon product. In some embodiments, a
biogenic activated product has an attrition resistance of particles
value that is comparable to, substantially similar to, or the same
as an attrition resistance of particles value associated with a
traditional activated carbon product. In some embodiments, a
biogenic activated carbon product has a hardness value that is
comparable to, substantially similar to, or the same as a hardness
value associated with a traditional activated carbon product. In
some embodiments, a biogenic activated carbon product has a
hardness value that is comparable to, substantially less than or
equal to about, or less than or equal to about a hardness value
associated with a traditional activated carbon product. In some
embodiments, a biogenic activated carbon product has a bulk density
value that is comparable to, substantially similar to, or the same
as a bulk density value associated with a traditional activated
carbon product. In some embodiments, a biogenic activated carbon
product has a bulk density value that is comparable to,
substantially less than or equal to about, or less than or equal to
about a bulk density value associated with a traditional activated
carbon product. In some embodiments, a biogenic activated carbon
product has an absorptive capacity that is comparable to,
substantially similar to, or the same as an absorptive capacity
associated with a traditional activated carbon product.
[0650] Prior to suitability or actual use in any product
applications, the disclosed biogenic activated carbons may be
analyzed, measured, and optionally modified (such as through
additives) in various ways. Some properties of potential interest,
other than chemical composition and energy content, include
density, particle size, surface area, microporosity, absorptivity,
adsorptivity, binding capacity, reactivity, desulfurization
activity, basicity, hardness, and Iodine Number.
[0651] Some variations of the present disclosure provide various
activated carbon products. Activated carbon is used in a wide
variety of liquid and gas-phase applications, including water
treatment, air purification, solvent vapor recovery, food and
beverage processing, sugar and sweetener refining, automotive uses,
and pharmaceuticals. For activated carbon, key product attributes
may include particle size, shape, and composition; surface area,
pore volume and pore dimensions, particle-size distribution, the
chemical nature of the carbon surface and interior, attrition
resistance of particles, hardness, bulk density, and adsorptive
capacity.
[0652] The surface area of the biogenic activated carbon may vary
widely. Exemplary surface areas range from about 400 m.sup.2/g to
about 2000 m.sup.2/g or higher, such as about 500 m.sup.2/g, 600
m.sup.2/g, 800 m.sup.2/g, 1000 m.sup.2/g, 1200 m.sup.2/g, 1400
m.sup.2/g, 1600 m.sup.2/g, or 1800 m.sup.2/g. Surface area
generally correlates to adsorption capacity.
[0653] The Iodine Number is a parameter used to characterize
activated carbon performance. The Iodine Number measures the degree
of activation of the carbon, and is a measure of micropore (e.g.,
0-20 .ANG.) content. It is an important measurement for
liquid-phase applications. Other pore-related measurements include
Methylene Blue, which measures mesopore content (e.g., 20-500
.ANG.); and Molasses Number, which measures macropore content
(e.g., >500 .ANG.). The pore-size distribution and pore volume
are important to determine ultimate performance. A typical bulk
density for the biogenic activated carbon is about 400 to 500
g/liter, such as about 450 g/liter.
[0654] Hardness or Abrasion Number is measure of activated carbon's
resistance to attrition. It is an indicator of activated carbon's
physical integrity to withstand frictional forces and mechanical
stresses during handling or use. Some amount of hardness is
desirable, but if the hardness is too high, excessive equipment
wear can result. Exemplary Abrasion Numbers, measured according to
ASTM D3802, range from about 1% to great than about 99%, such as
about 1%, about 5%, about 10%, about 15%, about 20%, about 25%,
about 30%, about 35%, about 40%, about 45%, about 50%, about 55%,
60%, about 65%, about 70%, about 75%, about 80%, about 85%, about
90%, about 95%, about 96%, about 97%, about 98%, about 99%, or
greater than about 99%.
[0655] In some embodiments, an optimal range of hardness can be
achieved in which the biogenic activated carbon is reasonably
resistant to attrition but does not cause abrasion and wear in
capital facilities that process the activated carbon. This optimum
is made possible in some embodiments of this disclosure due to the
selection of feedstock as well as processing conditions.
[0656] For example, it is known that coconut shells tend to produce
Abrasion Numbers of 99% or higher, so coconut shells would be a
less-than-optimal feedstock for achieving optimum hardness. In some
embodiments in which the downstream use can handle high hardness,
the process of this disclosure may be operated to increase or
maximize hardness to produce biogenic activated carbon products
having an Abrasion Number of about 75%, about 80%, about 85%, about
90%, about 95%, about 96%, about 97%, about 98%, about 99%, or
greater than about 99%.
[0657] The biogenic activated carbon provided by the present
disclosure has a wide range of commercial uses. For example,
without limitation, the biogenic activated carbon may be utilized
in emissions control, water purification, groundwater treatment,
wastewater treatment, air stripper applications, PCB removal
applications, odor removal applications, soil vapor extractions,
manufactured gas plants, industrial water filtration, industrial
fumigation, tank and process vents, pumps, blowers, filters,
pre-filters, mist filters, ductwork, piping modules, adsorbers,
absorbers, and columns.
[0658] Some variations provide a biogenic activated carbon
composition comprising, on a dry basis, about 55 wt % or more total
carbon, about 15 wt % or less hydrogen, and less than or equal to
about 1 wt % nitrogen; wherein the activated carbon composition is
characterized by an Iodine Number higher than about 500, and
wherein at least a portion of the carbon is present in the form of
graphene.
[0659] In some embodiments, the composition is responsive to an
externally applied magnetic field, or includes an additive that is
responsive to an externally applied magnetic field. Such an
additive may be iron or an iron-containing compound. The graphene
itself (with no additive) may be responsive to an externally
applied magnetic field.
[0660] Some variations provide a biogenic activated carbon
composition comprising, on a dry basis, about 55 wt % or more total
carbon, about 15 wt % or less hydrogen, less than or equal to about
1 wt % nitrogen, and from about 0.0001 wt % to about 1 wt % iron;
wherein at least a portion of the carbon is present in the form of
graphene, wherein the activated carbon composition is characterized
by an Iodine Number higher than about 500, and wherein the
composition is responsive to an externally applied magnetic
field.
[0661] Some variations provide a biogenic activated carbon
composition comprising, on a dry basis, about 55 wt % or more total
carbon, about 15 wt % or less hydrogen, less than or equal to about
1 wt % nitrogen, and from about 0.1 wt % to about 1 wt % iron;
wherein the activated carbon composition is characterized by an
Iodine Number higher than about 500, and wherein the composition is
responsive to an externally applied magnetic field.
[0662] Some variations provide a biogenic activated carbon
composition comprising, on a dry basis, about 55 wt % or more total
carbon, about 15 wt % or less hydrogen, and less than or equal to
about 1 wt % nitrogen; wherein the activated carbon composition is
characterized by an Iodine Number higher than about 500, and
wherein at least a portion of the carbon is present in the form of
graphene.
[0663] The present disclosure also provides a biogenic
graphene-containing product characterized by an Iodine Number
higher than about 500.
[0664] Some variations of this disclosure provide a method of using
a biogenic activated carbon composition to reduce emissions, the
method comprising: [0665] (a) providing activated carbon particles
comprising a biogenic activated carbon composition; [0666] (b)
providing a gas-phase emissions stream comprising at least one
selected contaminant; [0667] (c) providing an additive selected to
assist in removal of the selected contaminant from the gas-phase
emissions stream; [0668] (d) introducing the activated carbon
particles and the additive into the gas-phase emissions stream, to
adsorb at least a portion of the selected contaminant onto the
activated carbon particles, thereby generating contaminant-adsorbed
carbon particles within the gas-phase emissions stream; and [0669]
(e) separating at least a portion of the contaminant-adsorbed
carbon particles from the gas-phase emissions stream, to produce a
contaminant-reduced gas-phase emissions stream.
[0670] The additive for the biogenic activated carbon composition
may be provided as part of the activated carbon particles.
Alternatively, or additionally, the additive may be introduced
directly into the gas-phase emissions stream, into a fuel bed, or
into a combustion zone. Other ways of directly or indirectly
introducing the additive into the gas-phase emissions stream for
removal of the selected contaminant are possible, as will be
appreciated by one of skill in the art.
[0671] A selected contaminant (in the gas-phase emissions stream)
may be a metal, such as a metal is selected from the group
consisting of mercury, boron, selenium, arsenic, and any compound,
salt, and mixture thereof. A selected contaminant may be a
hazardous air pollutant, an organic compound (such as a VOC), or a
non-condensable gas, for example. In some embodiments, a biogenic
activated carbon product adsorbs, absorbs and/or chemisorbs a
selected contaminant in greater amounts than a comparable amount of
a non-biogenic activated carbon product. In some such embodiments,
the selected contaminant is a metal, a hazardous air pollutant, an
organic compound (such as a VOC), a non-condensable gas, or any
combination thereof. In some embodiments, the selected contaminant
comprises mercury. In some embodiments, the selected contaminant
comprises one or more VOCs. In some embodiments, the biogenic
activated carbon comprises at least about 1 wt % hydrogen and/or at
least about 10 wt % oxygen.
[0672] Hazardous air pollutants are those pollutants that cause or
may cause cancer or other serious health effects, such as
reproductive effects or birth defects, or adverse environmental and
ecological effects. Section 112 of the Clean Air Act, as amended,
is incorporated by reference herein in its entirety. Pursuant to
the Section 112 of the Clean Air Act, the United States
Environmental Protection Agency (EPA) is mandated to control 189
hazardous air pollutants. Any current or future compounds
classified as hazardous air pollutants by the EPA are included in
possible selected contaminants in the present context.
[0673] Volatile organic compounds, some of which are also hazardous
air pollutants, are organic chemicals that have a high vapor
pressure at ordinary, room-temperature conditions. Examples include
short-chain alkanes, olefins, alcohols, ketones, and aldehydes.
Many volatile organic compounds are dangerous to human health or
cause harm to the environment. EPA regulates volatile organic
compounds in air, water, and land. EPA's definition of volatile
organic compounds is described in 40 CFR Section 51.100, which is
incorporated by reference herein in its entirety.
[0674] Non-condensable gases are gases that do not condense under
ordinary, room-temperature conditions. Non-condensable gas may
include, but are not limited to, nitrogen oxides, carbon monoxide,
carbon dioxide, hydrogen sulfide, sulfur dioxide, sulfur trioxide,
methane, ethane, ethylene, ozone, ammonia, or combinations
thereof.
[0675] Multiple contaminants may be removed by the activated carbon
particles. In some embodiments, the contaminant-adsorbed carbon
particles include at least two contaminants, at least three
contaminants, or more. The biogenic activated carbon as disclosed
herein can allow multi-pollutant control as well as control of
certain targeted pollutants (e.g. selenium).
[0676] In certain embodiments, the contaminant-adsorbed carbon
particles include at least one, at least two, at least three, or
all of, carbon dioxide, nitrogen oxides, mercury, and sulfur
dioxide (in any combination).
[0677] The separation in step (e) may include filtration (e.g.,
fabric filters) or electrostatic precipitation (ESP), for example.
Fabric filters, also known as baghouses, may utilize engineered
fabric filter tubes, envelopes, or cartridges, for example. There
are several types of baghouses, including pulse-jet, shaker-style,
and reverse-air systems. The separation in step (e) may also
include scrubbing.
[0678] An electrostatic precipitator, or electrostatic air cleaner,
is a particulate collection device that removes particles from a
flowing gas using the force of an induced electrostatic charge.
Electrostatic precipitators are highly efficient filtration devices
that minimally impede the flow of gases through the device, and can
easily remove fine particulate matter from the air stream. An
electrostatic precipitator applies energy only to the particulate
matter being collected and therefore is very efficient in its
consumption of energy (electricity).
[0679] The electrostatic precipitator may be dry or wet. A wet
electrostatic precipitator operates with saturated gas streams to
remove liquid droplets such as sulfuric acid mist from industrial
process gas streams. Wet electrostatic precipitators may be useful
when the gases are high in moisture content, contain combustible
particulate, or have particles that are sticky in nature.
[0680] In some embodiments, the contaminant-adsorbed carbon
particles are treated to regenerate the activated carbon particles.
In some embodiments, the method includes thermally oxidizing the
contaminant-adsorbed carbon particles. The contaminant-adsorbed
carbon particles, or a regenerated form thereof, may be combusted
to provide energy.
[0681] In some embodiments, the additive is selected from an acid,
a base, a salt, a metal, a metal oxide, a metal hydroxide, a metal
halide, or a combination thereof. In certain embodiments, the
additive is selected from the group consisting of magnesium,
manganese, aluminum, nickel, iron, chromium, silicon, boron,
cerium, molybdenum, phosphorus, tungsten, vanadium, iron chloride,
iron bromide, magnesium oxide, dolomite, dolomitic lime, fluorite,
fluorospar, bentonite, calcium oxide, lime, sodium hydroxide,
potassium hydroxide, hydrogen bromide, hydrogen chloride, sodium
silicate, potassium permanganate, organic acids (e.g., citric
acid), and combinations thereof.
[0682] In some embodiments, the gas-phase emissions stream is
derived from combustion of a fuel comprising the biogenic activated
carbon composition.
[0683] In some embodiments relating specifically to mercury
removal, a method of using a biogenic activated carbon composition
to reduce mercury emissions comprises: [0684] (a) providing
activated carbon particles comprising a biogenic activated carbon
composition that includes iron or an iron-containing compound;
[0685] (b) providing a gas-phase emissions stream comprising
mercury; [0686] (c) introducing the activated carbon particles into
the gas-phase emissions stream, to adsorb at least a portion of the
mercury onto the activated carbon particles, thereby generating
mercury-adsorbed carbon particles within the gas-phase emissions
stream; and [0687] (d) separating at least a portion of the
mercury-adsorbed carbon particles from the gas-phase emissions
stream using electrostatic precipitation or filtration, to produce
a mercury-reduced gas-phase emissions stream.
[0688] In some embodiments, a method of using a biogenic activated
carbon composition to reduce emissions (e.g., mercury) further
comprises using the biogenic activated carbon as a fuel source. In
such embodiments, the high heat value of the biogenic activated
carbon product can be utilized in addition to its ability to reduce
emissions by adsorbing, absorbing and/or chemisorbing potential
pollutants. Thus, in an example embodiment, the biogenic activated
carbon product, when used as a fuel source and as a mercury control
product, prevents at least 70% of mercury from emanating from a
power plant, for example about 70%, about 75%, about 80%, about
85%, about 90%, about 95%, about 96%, about 97%, about 98%, 98.5%,
about 99%, about 99.1%, about 99.2%, about 99.3%, about 99.4%,
about 99.5%, about 99.6%, about 99.7%, about 99.8%, about 99.9%, or
greater than about 99.9% of mercury.
[0689] As an exemplary embodiment, biogenic activated carbon may be
injected (such as into the ductwork) upstream of a particulate
matter control device, such as an electrostatic precipitator or
fabric filter. In some cases, a flue gas desulfurization (dry or
wet) system may be downstream of the activated carbon injection
point. The activated carbon may be pneumatically injected as a
powder. The injection location will typically be determined by the
existing plant configuration (unless it is a new site) and whether
additional downstream particulate matter control equipment is
modified.
[0690] For boilers currently equipped with particulate matter
control devices, implementing biogenic activated carbon injection
for mercury control could entail: (i) injection of powdered
activated carbon upstream of the existing particulate matter
control device (electrostatic precipitator or fabric filter); (ii)
injection of powdered activated carbon downstream of an existing
electrostatic precipitator and upstream of a retrofit fabric
filter; or (iii) injection of powdered activated carbon between
electrostatic precipitator electric fields.
[0691] In some embodiments, powdered biogenic activated carbon
injection approaches may be employed in combination with existing
SO.sub.2 control devices. Activated carbon could be injected prior
to the SO.sub.2 control device or after the SO.sub.2 control
device, subject to the availability of a means to collect the
activated carbon sorbent downstream of the injection point.
[0692] When electrostatic precipitation is employed, the presence
of iron or an iron-containing compound in the activated carbon
particles can improve the effectiveness of electrostatic
precipitation, thereby improving mercury control.
[0693] The method optionally further includes separating the
mercury-adsorbed carbon particles, containing the iron or an
iron-containing compound, from carbon or ash particles that do not
contain the iron or an iron-containing compound. The carbon or ash
particles that do not contain the iron or an iron-containing
compound may be recovered for recycling, selling as a co-product,
or other use. Any separations involving iron or materials
containing iron may employ magnetic separation, taking advantage of
the magnetic properties of iron.
[0694] A biogenic activated carbon composition that includes iron
or an iron-containing compound is a "magnetic activated carbon"
product. That is, the material is susceptible to a magnetic field.
The iron or iron-containing compound may be separated using
magnetic separation devices. Additionally, the biogenic activated
carbon, which contains iron, may be separated using magnetic
separation. When magnetic separation is to be employed, magnetic
metal separators may be magnet cartridges, plate magnets, or
another known configuration.
[0695] Inclusion of iron or iron-containing compounds may
drastically improve the performance of electrostatic precipitators
for mercury control. Furthermore, inclusion of iron or
iron-containing compounds may drastically change end-of-life
options, since the spent activated carbon solids may be separated
from other ash.
[0696] In some embodiments, a magnetic activated carbon product can
be separated out of the ash stream. Under the ASTM standards for
use of fly ash in cement, the fly ash must come from coal products.
If wood-based activated carbon can be separated from other fly ash,
the remainder of the ash may be used per the ASTM standards for
cement production. Similarly, the ability to separate mercury-laden
ash may allow it to be better handled and disposed of, potentially
reducing costs of handling all ash from a certain facility.
[0697] In some embodiments, the same physical material may be used
in multiple processes, either in an integrated way or in sequence.
Thus, for example, an activated carbon may, at the end of its
useful life as a performance material, then be introduced to a
combustion process for energy value or to a metal process, etc.
[0698] For example, an activated carbon injected into an emissions
stream may be suitable to remove contaminants, followed by
combustion of the activated carbon particles and possibly the
contaminants, to produce energy and thermally destroy or chemically
oxidize the contaminants.
[0699] In some variations, a process for energy production
comprises: [0700] (a) providing a carbon-containing feedstock
comprising a biogenic activated carbon composition (which may
include one or more additives); and [0701] (b) oxidizing the
carbon-containing feedstock to generate energy and a gas-phase
emissions stream, [0702] wherein the presence of the biogenic
activated carbon composition within the carbon-containing feedstock
is effective to adsorb at least one contaminant produced as a
byproduct of the oxidizing or derived from the carbon-containing
feedstock, thereby reducing emissions of the contaminant.
[0703] In some embodiments, the contaminant, or a precursor
thereof, is contained within the carbon-containing feedstock. In
other embodiments, the contaminant is produced as a byproduct of
the oxidizing.
[0704] The carbon-containing feedstock may further include biomass,
coal, or any other carbonaceous material, in addition to the
biogenic activated carbon composition. In certain embodiments, the
carbon-containing feedstock consists essentially of the biogenic
activated carbon composition as the sole fuel source.
[0705] The selected contaminant may be a metal selected from the
group consisting of mercury, boron, selenium, arsenic, and any
compound, salt, and mixture thereof; a hazardous air pollutant; an
organic compound (such as a VOC); a non-condensable gas selected
from the group consisting of nitrogen oxides, carbon monoxide,
carbon dioxide, hydrogen sulfide, sulfur dioxide, sulfur trioxide,
methane, ethane, ethylene, ozone, and ammonia; or any combinations
thereof. In some embodiments, a biogenic activated carbon product
adsorbs, absorbs and/or chemisorbs a selected contaminant in
greater amounts than a comparable amount of a non-biogenic
activated carbon product. In some such embodiments, the selected
contaminant is a metal, a hazardous air pollutant, an organic
compound (such as a VOC), a non-condensable gas, or any combination
thereof. In some embodiments, the selected contaminant comprises
mercury. In some embodiments, the selected contaminant comprises
one or more VOCs. In some embodiments, the biogenic activated
carbon comprises at least about 1 wt % hydrogen and/or at least
about 10 wt % oxygen.
[0706] The biogenic activated carbon and the principles of the
disclosure may be applied to liquid-phase applications, including
processing of water, aqueous streams of varying purities, solvents,
liquid fuels, polymers, molten salts, and molten metals, for
example. As intended herein, "liquid phase" includes slurries,
suspensions, emulsions, multiphase systems, or any other material
that has (or may be adjusted to have) at least some amount of a
liquid state present.
[0707] A method of using a biogenic activated carbon composition to
purify a liquid, in some variations, includes the following steps:
[0708] (a) providing activated carbon particles comprising a
biogenic activated carbon composition; [0709] (b) providing a
liquid comprising at least one selected contaminant; [0710] (c)
providing an additive selected to assist in removal of the selected
contaminant from the liquid; and [0711] (d) contacting the liquid
with the activated carbon particles and the additive, to adsorb at
least a portion of the at least one selected contaminant onto the
activated carbon particles, thereby generating contaminant-adsorbed
carbon particles and a contaminant-reduced liquid.
[0712] The additive may be provided as part of the activated carbon
particles. Or, the additive may be introduced directly into the
liquid. In some embodiments, additives--which may be the same, or
different--are introduced both as part of the activated carbon
particles as well as directly into the liquid.
[0713] In some embodiments relating to liquid-phase applications,
an additive is selected from an acid, a base, a salt, a metal, a
metal oxide, a metal hydroxide, a metal halide, or a combination
thereof. For example an additive may be selected from the group
consisting of magnesium, manganese, aluminum, nickel, iron,
chromium, silicon, boron, cerium, molybdenum, phosphorus, tungsten,
vanadium, iron chloride, iron bromide, magnesium oxide, dolomite,
dolomitic lime, fluorite, fluorospar, bentonite, calcium oxide,
lime, sodium hydroxide, potassium hydroxide, hydrogen bromide,
hydrogen chloride, sodium silicate, potassium permanganate, organic
acids (e.g., citric acid), and combinations thereof.
[0714] In some embodiments, the selected contaminant (in the liquid
to be treated) is a metal, such as a metal selected from the group
consisting of arsenic, boron, selenium, mercury, and any compound,
salt, and mixture thereof. In some embodiments, the selected
contaminant is an organic compound (such as a VOC), a halogen, a
biological compound, a pesticide, or a herbicide. The
contaminant-adsorbed carbon particles may include two, three, or
more contaminants. In some embodiments, a biogenic activated carbon
product adsorbs, absorbs and/or chemisorbs a selected contaminant
in greater amounts than a comparable amount of a non-biogenic
activated carbon product. In some such embodiments, the selected
contaminant is a metal, a hazardous air pollutant, an organic
compound (such as a VOC), a non-condensable gas, or any combination
thereof. In some embodiments, the selected contaminant comprises
mercury. In some embodiments, the selected contaminant comprises
one or more VOCs. In some embodiments, the biogenic activated
carbon comprises at least about 1 wt % hydrogen and/or at least
about 10 wt % oxygen.
[0715] The liquid to be treated will typically be aqueous, although
that is not necessary for the principles of this disclosure. In
some embodiments, step (c) includes contacting the liquid with the
activated carbon particles in a fixed bed. In other embodiments,
step (c) includes contacting the liquid with the activated carbon
particles in solution or in a moving bed.
[0716] Some variations provide a method of using a biogenic
activated carbon composition to remove at least a portion of a
sulfur-containing contaminant from a liquid, the method comprising:
[0717] (a) providing activated-carbon particles comprising a
biogenic activated carbon composition; [0718] (b) providing a
liquid containing a sulfur-containing contaminant; [0719] (c)
providing an additive selected to assist in removal of the
sulfur-containing contaminant from the liquid; and [0720] (d)
contacting the liquid with the activated-carbon particles and the
additive, to adsorb or absorb at least a portion of the
sulfur-containing contaminant onto or into the activated-carbon
particles.
[0721] In some embodiments, the sulfur-containing contaminant is
selected from the group consisting of elemental sulfur, sulfuric
acid, sulfurous acid, sulfur dioxide, sulfur trioxide, sulfate
anions, bisulfate anions, sulfite anions, bisulfate anions, thiols,
sulfides, disulfides, polysulfides, thioethers, thioesters,
thioacetals, sulfoxides, sulfones, thiosulfinates, sulfimides,
sulfoximides, sulfonediimines, sulfur halides, thioketones,
thioaldehydes, sulfur oxides, thiocarboxylic acids, thioamides,
sulfonic acids, sulfinic acids, sulfenic acids, sulfonium,
oxosulfonium, sulfuranes, persulfuranes, and combinations, salts,
or derivatives thereof. For example, the sulfur-containing
contaminant may be a sulfate, in anionic and/or salt form.
[0722] In some embodiments, the biogenic activated carbon
composition comprises 55 wt % or more total carbon; 15 wt % or less
hydrogen; and 1 wt % or less nitrogen; and an additive if provided
as part of the activated-carbon particles. The additive may be
selected from an acid, a base, a salt, a metal, a metal oxide, a
metal hydroxide, a metal halide, iodine, an iodine compound, or a
combination thereof. The additive may alternatively (or
additionally) be introduced directly into the liquid.
[0723] In some embodiments, step (d) includes filtration of the
liquid. In these or other embodiments, step (d) includes osmosis of
the liquid. The activated-carbon particles and the additive may be
directly introduced to the liquid prior to osmosis. The
activated-carbon particles and the additive may be employed in
pre-filtration prior to osmosis. In certain embodiments, the
activated-carbon particles and the additive are incorporated into a
membrane for osmosis. For example, known membrane materials such as
cellulose acetate may be modified by introducing the
activated-carbon particles and/or additives within the membrane
itself or as a layer on one or both sides of the membrane. Various
thin-film carbon-containing composites could be fabricated with the
activated-carbon particles and additives.
[0724] In some embodiments, step (d) includes direct addition of
the activated-carbon particles to the liquid, followed by for
example sedimentation of the activated-carbon particles with the
sulfur-containing contaminant from the liquid.
[0725] The liquid may be an aqueous liquid, such as water. In some
embodiments, the water is wastewater associated with a process
selected from the group consisting of metal mining, acid mine
drainage, mineral processing, municipal sewer treatment, pulp and
paper, ethanol, and any other industrial process that is capable of
discharging sulfur-containing contaminants in wastewater. The water
may also be (or be part of) a natural body of water, such as a
lake, river, or stream.
[0726] Some variations provide a process to reduce the
concentration of sulfates in water, the process comprising: [0727]
(a) providing activated-carbon particles comprising a biogenic
activated carbon composition; [0728] (b) providing a volume or
stream of water containing sulfates; [0729] (c) providing an
additive selected to assist in removal of the sulfates from the
water; and [0730] (d) contacting the water with the
activated-carbon particles and the additive, to adsorb or absorb at
least a portion of the sulfates onto or into the activated-carbon
particles.
[0731] In some embodiments, the sulfates are reduced to a
concentration of about 50 mg/L or less in the water, such as a
concentration of about 10 mg/L or less in the water. In some
embodiments, the sulfates are reduced, as a result of absorption
and/or adsorption into the biogenic activated carbon composition,
to a concentration of about 100 mg/L, 75 mg/L, 50 mg/L, 25 mg/L, 20
mg/L, 15 mg/L, 12 mg/L, 10 mg/L, 8 mg/L, or less in the wastewater
stream. In some embodiments, the sulfate is present primarily in
the form of sulfate anions and/or bisulfate anions. Depending on
pH, the sulfate may also be present in the form of sulfate
salts.
[0732] The water may be derived from, part of, or the entirety of a
wastewater stream. Exemplary wastewater streams are those that may
be associated with a metal mining, acid mine drainage, mineral
processing, municipal sewer treatment, pulp and paper, ethanol, or
any other industrial process that could discharge sulfur-containing
contaminants to wastewater. The water may be a natural body of
water, such as a lake, river, or stream. In some embodiments, the
process is conducted continuously. In other embodiments, the
process is conducted in batch.
[0733] The biogenic activated carbon composition comprises 55 wt %
or more total carbon; 15 wt % or less hydrogen; and 1 wt % or less
nitrogen, in some embodiments. The additive may be selected from an
acid, a base, a salt, a metal, a metal oxide, a metal hydroxide, a
metal halide, iodine, an iodine compound, or a combination thereof.
The additive is provided as part of the activated-carbon particles
and/or is introduced directly into the water.
[0734] Step (d) may include, but is not limited to, filtration of
the water, osmosis of the water, and/or direct addition (with
sedimentation, clarification, etc.) of the activated-carbon
particles to the water.
[0735] When osmosis is employed, the activated carbon can be used
in several ways within, or to assist, an osmosis device. In some
embodiments, the activated-carbon particles and the additive are
directly introduced to the water prior to osmosis. The
activated-carbon particles and the additive are optionally employed
in pre-filtration prior to the osmosis. In certain embodiments, the
activated-carbon particles and the additive are incorporated into a
membrane for osmosis.
[0736] This disclosure also provides a method of using a biogenic
activated carbon composition to remove a sulfur-containing
contaminant from a gas phase, the method comprising: [0737] (a)
providing activated-carbon particles comprising a biogenic
activated carbon composition; [0738] (b) providing a gas-phase
emissions stream comprising at least one sulfur-containing
contaminant; [0739] (c) providing an additive selected to assist in
removal of the sulfur-containing contaminant from the gas-phase
emissions stream; [0740] (d) introducing the activated-carbon
particles and the additive into the gas-phase emissions stream, to
adsorb or absorb at least a portion of the sulfur-containing
contaminant onto the activated-carbon particles; and [0741] (e)
separating at least a portion of the activated-carbon particles
from the gas-phase emissions stream.
[0742] In some embodiments, the sulfur-containing contaminant is
selected from the group consisting of elemental sulfur, sulfuric
acid, sulfurous acid, sulfur dioxide, sulfur trioxide, sulfate
anions, bisulfate anions, sulfite anions, bisulfate anions, thiols,
sulfides, disulfides, polysulfides, thioethers, thioesters,
thioacetals, sulfoxides, sulfones, thiosulfinates, sulfimides,
sulfoximides, sulfonediimines, sulfur halides, thioketones,
thioaldehydes, sulfur oxides, thiocarboxylic acids, thioamides,
sulfonic acids, sulfinic acids, sulfenic acids, sulfonium,
oxosulfonium, sulfuranes, persulfuranes, and combinations, salts,
or derivatives thereof.
[0743] The biogenic activated carbon composition may include 55 wt
% or more total carbon; 15 wt % or less hydrogen; 1 wt % or less
nitrogen; and an additive selected from an acid, a base, a salt, a
metal, a metal oxide, a metal hydroxide, a metal halide, iodine, an
iodine compound, or a combination thereof. The additive may be
provided as part of the activated-carbon particles, or may be
introduced directly into the gas-phase emissions stream.
[0744] In some embodiments, the gas-phase emissions stream is
derived from combustion of a fuel comprising the biogenic activated
carbon composition. For example, the gas-phase emissions stream may
be derived from co-combustion of coal and the biogenic activated
carbon composition.
[0745] In some embodiments, separating in step (e) comprises
filtration. In these or other embodiments, separating in step (e)
comprises electrostatic precipitation. In any of these embodiments,
separating in step (e) may include scrubbing, which may be wet
scrubbing, dry scrubbing, or another type of scrubbing.
[0746] The biogenic activated carbon composition may comprise 55 wt
% or more total carbon; 15 wt % or less hydrogen; 1 wt % or less
nitrogen; 0.5 wt % or less phosphorus; and 0.2 wt % or less sulfur.
In various embodiments, the additive is selected from an acid, a
base, a salt, a metal, a metal oxide, a metal hydroxide, a metal
halide, iodine, an iodine compound, or a combination thereof. The
additive is provided as part of the activated-carbon particles, in
some embodiments; alternatively or additionally, the additive may
be introduced directly into the gas-phase emissions stream.
[0747] In certain embodiments, the gas-phase emissions stream is
derived from combustion of a fuel comprising the biogenic activated
carbon composition. For example, the gas-phase emissions stream may
be derived from co-combustion of coal and the biogenic activated
carbon composition.
[0748] The biogenic activated carbon composition comprises 55 wt %
or more total carbon; 15 wt % or less hydrogen; 1 wt % or less
nitrogen; 0.5 wt % or less phosphorus; and 0.2 wt % or less sulfur,
in some embodiments. The additive may be selected from an acid, a
base, a salt, a metal, a metal oxide, a metal hydroxide, a metal
halide, iodine, an iodine compound, or a combination thereof. The
additive may be provided as part of the activated-carbon particles.
The additive may optionally be introduced directly into the
wastewater stream.
[0749] The contaminant-adsorbed carbon particles may be further
treated to regenerate the activated carbon particles. After
regeneration, the activated carbon particles may be reused for
contaminant removal, or may be used for another purpose, such as
combustion to produce energy. In some embodiments, the
contaminant-adsorbed carbon particles are directly oxidized
(without regeneration) to produce energy. In some embodiments, with
the oxidation occurs in the presence of an emissions control device
(e.g., a second amount of fresh or regenerated activated carbon
particles) to capture contaminants released from the oxidation of
the contaminant-absorbed carbon particles.
[0750] In some embodiments, biogenic activated carbon according to
the present disclosure can be used in any other application in
which traditional activated carbon might be used. In some
embodiments, the biogenic activated carbon is used as a total
(i.e., 100%) replacement for traditional activated carbon. In some
embodiments, biogenic activated carbon comprises essentially all or
substantially all of the activated carbon used for a particular
application. In some embodiments, an activated carbon composition
comprises about 1% to about 100% of biogenic activated carbon, for
example, about 1%, about 2%, about 5%, about 10%, about 15%, about
20%, about 25%, about 30%, about 35%, about 40%, about 45%, about
50%, about 55%, about 60%, about 65%, about 70%, about 75%, about
80%, about 85%, about 90%, about 95%, about 96%, about 97%, about
98%, about 99%, or about 100% biogenic activated carbon.
[0751] For example and without limitation, biogenic activated
carbon can be used-alone or in combination with a traditional
activated carbon product-in filters. In some embodiments, a filter
comprises an activated carbon component consisting of, consisting
essentially of, or consisting substantially of a biogenic activated
carbon. In some embodiments, a filter comprises an activated carbon
component comprising about 1% to about 100% of biogenic activated
carbon, for example, about 1%, about 2%, about 5%, about 10%, about
15%, about 20%, about 25%, about 30%, about 35%, about 40%, about
45%, about 50%, about 55%, about 60%, about 65%, about 70%, about
75%, about 80%, about 85%, about 90%, about 95%, about 96%, about
97%, about 98%, about 99%, or about 100% biogenic activated
carbon.
[0752] In some embodiments, a packed bed or packed column comprises
an activated carbon component consisting of, consisting essentially
of, or consisting substantially of a biogenic activated carbon. In
some embodiments, a packed bed or packed column comprises an
activated carbon component comprising about 1% to about 100% of
biogenic activated carbon, for example, about 1%, about 2%, about
5%, about 10%, about 15%, about 20%, about 25%, about 30%, about
35%, about 40%, about 45%, about 50%, about 55%, about 60%, about
65%, about 70%, about 75%, about 80%, about 85%, about 90%, about
95%, about 96%, about 97%, about 98%, about 99%, or about 100%
biogenic activated carbon. In such embodiments, the biogenic
activated carbon has a size characteristic suitable for the
particular packed bed or packed column.
[0753] The above description should not be construed as limiting in
any way as to the potential applications of the biogenic activated
carbon. Injection of biogenic activated carbon into gas streams may
be useful for control of contaminant emissions in gas streams or
liquid streams derived from coal-fired power plants, biomass-fired
power plants, metal processing plants, crude-oil refineries,
chemical plants, polymer plants, pulp and paper plants, cement
plants, waste incinerators, food processing plants, gasification
plants, and syngas plants.
[0754] Essentially any industrial process or site that employs
fossil fuel or biomass for generation of energy or heat, can
benefit from gas treatment by the biogenic activated carbon
provided herein. For liquid-phase applications, a wide variety of
industrial processes that use or produce liquid streams can benefit
from treatment by the biogenic activated carbon provided
herein.
[0755] Additionally, when the biogenic activated carbon is
co-utilized as a fuel source, either in parallel with its use for
contaminant removal or in series following contaminant removal (and
optionally following some regeneration), the biogenic activated
carbon (i) has lower emissions per Btu energy output than fossil
fuels; (ii) has lower emissions per Btu energy output than biomass
fuels; and (iii) can reduce emissions from biomass or fossil fuels
when co-fired with such fuels. It is noted that the biogenic
activated carbon may also be mixed with coal or other fossil fuels
and, through co-combustion, the activated carbon enables reduced
emissions of mercury, SO.sub.2, or other contaminants.
[0756] In some variations, a method of using a biogenic activated
carbon composition comprises: [0757] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein the activated
carbon composition is characterized by an Iodine Number higher than
about 500, and wherein the composition is responsive to an
externally applied magnetic field; [0758] (b) providing a gas or
liquid stream containing one or more contaminants; and [0759] (c)
contacting the gas or liquid stream with the biogenic activated
carbon composition to absorb, adsorb, or react at least a portion
of the one or more contaminants from the gas or liquid stream.
[0760] In some variations, a method of using a biogenic activated
carbon composition comprises: [0761] (a) obtaining a biogenic
activated carbon composition comprising, on a dry basis, about 55
wt % or more total carbon, about 15 wt % or less hydrogen, and less
than or equal to about 1 wt % nitrogen; wherein the activated
carbon composition is characterized by an Iodine Number higher than
about 500, and wherein at least a portion of the carbon is present
in the form of graphene; [0762] (b) providing a gas or liquid
stream containing one or more contaminants; and [0763] (c)
contacting the gas or liquid stream with the biogenic activated
carbon composition to absorb, adsorb, or react at least a portion
of the one or more contaminants from the gas or liquid stream.
[0764] Methods of using graphene are also disclosed. In some
embodiments, a method of using graphene comprises: [0765] (a)
obtaining a biogenic activated carbon composition comprising, on a
dry basis, about 55 wt % or more total carbon, about 15 wt % or
less hydrogen, and less than or equal to about 1 wt % nitrogen;
wherein at least a portion of the carbon is present in the form of
graphene; [0766] (b) optionally separating the graphene from the
biogenic activated carbon composition; [0767] (c) using the
graphene, in separated form or as part of the biogenic activated
carbon composition, for filtration of a liquid (e.g., water)
containing a contaminant.
[0768] In some embodiments, a method of using graphene comprises:
[0769] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0770] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0771] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, for filtration of a gas containing a
contaminant
[0772] In some embodiments, a method of using graphene comprises:
[0773] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0774] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0775] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, in an adhesive, sealant, coating,
paint, or ink.
[0776] In some embodiments, a method of using graphene comprises:
[0777] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0778] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0779] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, as a component in a composite
material to adjust mechanical or electrical properties of said
composite material.
[0780] In some embodiments, a method of using graphene comprises:
[0781] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0782] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0783] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, as a catalyst, a catalyst support, a
battery electrode material, or a fuel cell electrode material.
[0784] In some embodiments, a method of using graphene comprises:
[0785] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0786] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0787] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, in a graphene-based circuit or memory
system.
[0788] In some embodiments, a method of using graphene comprises:
[0789] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0790] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0791] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, as an energy-storage material or as a
supercapacitor component.
[0792] In some embodiments, a method of using graphene comprises:
[0793] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0794] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0795] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, as a sink for static electricity
dissipation in a liquid or vapor fuel delivery system.
[0796] In some embodiments, a method of using graphene comprises:
[0797] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0798] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0799] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, in a high-bandwidth communication
system.
[0800] In some embodiments, a method of using graphene comprises:
[0801] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0802] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0803] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, as a component of an infrared,
chemical, or biological sensor.
[0804] In some embodiments, a method of using graphene comprises:
[0805] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0806] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0807] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, as a component of an electronic
display.
[0808] In some embodiments, a method of using graphene comprises:
[0809] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0810] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0811] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, as a component of a photovoltaic
cell.
[0812] In some embodiments, a method of using graphene comprises:
[0813] (a) obtaining a biogenic activated carbon composition
comprising, on a dry basis, about 55 wt % or more total carbon,
about 15 wt % or less hydrogen, and less than or equal to about 1
wt % nitrogen; wherein at least a portion of the carbon is present
in the form of graphene; [0814] (b) optionally separating the
graphene from the biogenic activated carbon composition; [0815] (c)
using the graphene, in separated form or as part of the biogenic
activated carbon composition, to form a graphene aerogel.
EXAMPLES
Example 1
Production of Biogenic Activated Carbon Product with Additive
[0816] This example demonstrates the production of a biogenic
activated carbon product having an additive, namely iron(II)
bromide.
[0817] An aqueous solution of iron(II) bromide hydrate was created
by mixing 72.6 grams of iron(II) bromide hydrate into 1 gallon of
water (e.g., 1.0% bromine aqueous solution). This solution was
added to 5.23 pounds (2.37 kg) of air-dried (12% moisture content)
red pine wood chips. Each wood chip was approximately
1''.times.1/2''.times.1/8''.
[0818] The container of wood chips and solution was sealed with a
water tight lid. The contents were mixed periodically over the
course of approximately four hours by tipping and rolling the
container and contents. The wood chips and solution were kept
sealed overnight to allow for saturation of the wood chips with the
solution.
[0819] Thereafter, the contents were transferred to an open
water-proof tub and allowed to air dry for several hours, with
periodic mixing until all free liquid had been absorbed by the wood
chips or evaporated. The contents were transferred to an air-dryer
and allowed to dry overnight.
[0820] The pretreated, air-dried wood chips were verified to have
12% moisture content. The mass of the pretreated, air dried wood
chips was determined to be 5.25 lbs (2.38 kg). The contents were
transferred to a pyrolysis reactor and processed at the following
conditions:
[0821] 370.degree. C. four-zone heat
Hot nitrogen introduction system operating at 300.degree. C.
[0822] Gas extraction probe flow rate of 0.4 cubic feet per
minute
[0823] Low oxygen environment
[0824] Product processing time of 30 minutes
[0825] The finished product was removed from the reactor at a
temperature of less than or equal to about 100.degree. C. Upon
reaching room temperature (approximately 23.degree. C.), the
finished product had a mass of 2.5 pounds (1.14 kg), indicating a
mass yield of 47.6% based upon feedstock mass at 12% moisture
content. On a dry basis (correcting out the 12% moisture), the mass
yield was 54.1%. As shown in Table 1 below, this represents an
increase of 28-39% in mass yield over untreated wood chips
processed under the same conditions.
TABLE-US-00001 TABLE 1 Pretreatment of Biomass with 1.0% Aqueous
Iron(II) Bromide Increases Mass Yield. Pretreatment Mass Yield (12%
Moisture) Mass Yield (Dry Basis) Iron(II) Bromide 47.6% 54.1% None
34.3% 39.0% None 35.4% 40.2% None 37.2% 42.2%
[0826] These data indicate a significant improvement in the mass
yield for wood chips treated with an iron (II) bromide solution
prior to pyrolytic processing.
Example 2
Performance of Iron(II) Bromide Pretreated Biogenic Activated
Carbon
[0827] A sample of the iron(II) bromide pretreated product prepared
according to Example 1 was size reduced and utilized in a mercury
capture experiment.
[0828] A sampling tube was prepared with an aliquot of the iron(II)
bromide pretreated biogenic activated carbon. A second tube
containing a reference material prepared in accordance with USEPA
Method 30B (supplied by Ohio Lumex) was used for comparison. Both
tubes sampled a vapor-phase mercury air sample at identical rates
(500 cubic centimeters per minute) for 25 minutes. The sampling
media from both tubes were immediately analyzed for mercury using
an Ohio Lumex RA-915 Plus Zeeman atomic absorption spectrometry
instrument. Both sets of tubes had collected the same mass on the
front sections (calculated as 136 ng/m.sup.3), and below detectable
levels for the second (backup) sections. As defined in Method 30B,
this indicates 100% capture of vapor phase mercury by each of the
respective reagents.
Example 3
Properties of Pretreated Biogenic Activated Carbon Products
[0829] Size-reduced pretreated biogenic activated carbons prepared
according to the method of Example 1 were subjected to a magnet.
Table 2 below summarizes the magnetic properties.
TABLE-US-00002 TABLE 2 Magnetic Properties of Pretreated Biogenic
Activated Carbon Products. Sample Pretreatment Magnetic A-1 1%
iron(II) bromide (aq) Yes A-2 0.5% iron(II) chloride (aq) Yes A-3
0.25% iron(II) chloride (aq) Yes A-4 0.1% iron(II) chloride (aq)
Yes B 1% sodium halide (aq) No C 1% potassium halide (aq) No D 1%
calcium halide (aq) No E 1% manganese halide (aq) No
[0830] To investigate the dispersion of magnetic particles in the
biogenic activated carbon material, an electromicrograph of a
portion of the Sample A material was obtained. As shown in FIG.
14A, dispersion of the magnetic particles is not limited to the
surface of the material, but rather is pervasive, complete, and
essentially uniform throughout. For comparison, FIG. 14B shows a
biogenic activated carbon product prepared by an identical method
except without iron(II) halide pretreatment. FIG. 15 illustrates
the magnetic properties of the biogenic activated carbon product
pretreated with iron(II) bromide as described herein.
Example 4
Reduction of Acid Gases by Potassium Permanganate-Pretreated
Biogenic Activated Carbon
[0831] A synthetic mixture of gases (nitrogen with 24.7 ppm carbon
monoxide, 24.9 ppm nitric oxide, and 25.1 ppm sulfur dioxide; Linde
Gas North America) was used to evaluate the adsorptive properties
of biogenic activated carbon pretreated with 1% aqueous potassium
permanganate according to Example 1. A MKS model 2030 Fourier
Transform Infrared (FTIR) detector was used to measure the
concentration of CO, NO and SO.sub.2 in real time.
[0832] A sample of 0.4 grams of the potassium permanganate
pretreated biogenic activated carbon was loaded into a Volatile
Organic Sampling Train (VOST) tube and secured in place with filter
frits and spring clamps.
[0833] The FTIR detector was operated on the standardize gas stream
to establish the baseline measured values. Then the VOST tube
containing the test material was placed into the gas stream before
the detector. As shown in FIG. 16, 100% of the sulfur dioxide was
rapidly removed. In addition, about 20% of the nitric oxide was
removed, while the carbon monoxide remained unchanged. The arrow in
FIG. 16 at about 90 seconds indicates t.sub.0, the moment when the
VOST tube was inserted into the gas stream.
Example 5
Reduction of Carbon Dioxide Emissions by Potassium
Permanganate-Pretreated Biogenic Activated Carbon Product
[0834] A synthetic mixture of gases (nitrogen with 8.52% carbon
dioxide and 11.00% oxygen; Linde Gas North America) was used to
evaluate the adsorptive properties of biogenic activated carbon
pretreated with 1% aqueous potassium permanganate according to
Example 1.
[0835] A sample of 0.4 grams of the potassium permanganate
pretreated biogenic activated carbon was loaded into a Volatile
Organic Sampling Train (VOST) tube and secured in place with filter
frits and spring clamps. A MKS model 2030 Fourier Transform
Infrared (FTIR) detector was used to measure the concentration of
CO.sub.2 in real time.
[0836] The FTIR detector was operated on the standardize gas stream
at a flow of 300 ccm to establish the baseline measured values.
Then the VOST tube containing the test material was placed into the
gas stream before the detector. As shown in FIG. 17, a large amount
of CO.sub.2 was initially adsorbed, followed by an equilibration
period which resulted in an average adsorption of 2.6% of the
carbon dioxide. The black arrow in FIG. 17 at about 90 seconds
indicates t.sub.0, the moment when the VOST tube was inserted into
the gas stream; the gray arrow at about 10.3 minutes indicates
t.sub.F, the moment the VOST tube was removed from the gas
stream.
Example 6
Preparation of Biogenic Activated Carbon--General Method
[0837] Wood substrate red pine large chips, Douglas fir cylinders
(1.25-inch diameter pieces) and Douglas fir pieces (approximately 2
inches by 2 inches), were loaded into a loading hopper having an
optionally heated nitrogen gas flow. Optionally, a 1% aqueous
solution of an additive (e.g., NaOH and/or KOH) was applied by
spray to the wood substrate while in the hopper or by soaking the
biomass in the aqueous additive solution. Regardless of the
application method, the additive solution was allowed to penetrate
the biomass for 30 minutes before the biomass was dried. Once the
reactor had reached the desired temperature, rotation of the
reactor was initiated and the wood substrate was fed slowly by
activating the material feed system. Average residence times in the
heated portion of the reactor for each batch are indicated in Table
3. After exiting the heated portion of the reactor, the pyrolyzed
material collected in a discharge hopper. A conveyor removed the
biogenic activated carbon product from the discharge hopper for
further analysis.
[0838] Biogenic activated carbon was prepared according to the
General Method above using various feedstock sizes, varying reactor
temperatures, heated or ambient nitrogen, additive, and residence
times. Table 3 summarizes the pyrolysis parameters for each
batch.
TABLE-US-00003 TABLE 3 Preparation of Biogenic Activated Carbon.
Substrate Reactor Nitrogen Residence Sample Size Temp. Temp.
Additive Time A Large chips 371.degree. C. Ambient None 0.5 hours
(20-25.degree. C.) B Large chips 350.degree. C. Ambient None 0.5
hours C Large chips 350.degree. C. 300.degree. C. None 0.5 hours D
1.25-inch 600.degree. C. 300.degree. C. None 2 hours cylinders E 2
.times. 2 inches 600.degree. C. 300.degree. C. None 2 hours F Large
chips 480.degree. C. Ambient None 4 hours G Large chips 480.degree.
C. Ambient KOH 4 hours H Large chips 370.degree. C. Ambient KOH 2.5
hours I Large chips 370.degree. C. Ambient KOH 2 hours J1 Treated
Input N/A N/A NaOH N/A J2 J1 Output 370.degree. C. Ambient NaOH 2
hours
Example 7
Analysis of Biogenic Activated Carbon
[0839] Parameters of the biogenic activated carbon products
prepared according to the General Method of Example 6 were analyzed
according to Table 4 below.
TABLE-US-00004 TABLE 4 Methods Used to Analyze Biogenic Activated
Carbon. Parameter Method Moisture (total) ASTM D3173 Ash content
ASTM D3174 Volatile Matter content ASTM D3175 Fixed Carbon content
(by calculation) ASTM D3172 Sulfur content ASTM D3177 Heating Value
(BTU per pound) ASTM D5865 Carbon content ASTM D5373 Hydrogen
content ASTM D5373 Nitrogen content ASTM D5373 Oxygen content (by
calculation) ASTM D3176
[0840] Results for Samples A through F, which were prepared without
the use of additives, are shown in Table 5 below.
TABLE-US-00005 TABLE 5 Characteristics of Biogenic Activated Carbon
Products A Through F. Sample A B C D E F Moisture (wt. %) 2.42 3.02
3.51 0.478 0.864 4.25 Ash (wt. %) 1.16 0.917 0.839 1.03 1.06 1.43
Volatile Matter (wt. %) 38.7 46.4 42.8 2.8 17.0 18.4 Fixed Carbon
(wt. %) 57.7 49.4 52.9 95.7 81.0 76.0 Sulfur (wt. %)
ND.sup..dagger. ND ND ND ND ND Heat Value (BTU/lb.) 12,807 12,452
12,346 14,700 13,983 13,313 Carbon (wt. %) 73.3 71.2 71.0
NT.sup..dagger-dbl. NT 84.1 Hydrogen (wt. %) 4.47 4.85 4.63 NT NT
2.78 Nitrogen (wt. %) 0.251 0.227 0.353 NT NT 0.259 Oxygen (wt. %)
18.3 19.7 19.6 NT NT 7.13 .sup..dagger.ND: less than or equal to
about 0.05 wt. % sulfur content. .sup..dagger-dbl.NT: Not
Tested.
[0841] Results for Samples G through J2, which were prepared with
the use of additives, are shown in Table 6 below.
TABLE-US-00006 TABLE 6 Characteristics of Biogenic Activated Carbon
Products G Through J2. Sample .fwdarw. G H I J1 J2 Moisture (wt. %)
3.78 5.43 1.71 15.2 4.05 Ash (wt. %) 5.97 12.6 15.8 7.9 20.2
Volatile Matter 17.8 30.2 19.7 59.1 25.3 (wt. %) Fixed Carbon 72.5
51.7 62.8 17.8 50.5 (wt. %) Sulfur (wt. %) ND.sup..dagger. ND ND ND
ND Heat Value 12,936 10,530 11,997 6,968 9,639 (BTU/lb.) Carbon
(wt. %) 81.1 64.4 69.6 41.9 67.2 Hydrogen (wt. %) 2.6 3.73 3.82
4.64 3.78 Nitrogen (wt. %) 0.20 0.144 0.155 0.145 0.110 Oxygen (wt.
%) 6.31 13.6 8.91 30.2 4.6 .sup..dagger.ND: less than or equal to
about 0.05 wt. % sulfur content.
Example 8
Production of a High Heat Value Biogenic Activated Carbon
Product
[0842] This example demonstrates production of a biogenic activated
carbon product having a high heat value.
[0843] A feedstock comprising Douglas fir cylindrical pieces
(11/8'' diameter, approx. 1.5-inch lengths) was pyrolyzed according
to the General Method of Example 6. The reactor was heated to
600.degree. C. and the feedstock was pyrolyzed with a residence
time of 30 minutes. After cooling, the resulting biogenic activated
carbon product was analyzed according to the methods described in
Example 7. Results are shown in Table 7.
TABLE-US-00007 TABLE 7 Analysis of High Heat Value Biogenic
Activated Carbon Product. Ash & Parameter ASTM Method
As-Received Moisture Free Moisture Free Proximate Analysis Moisture
(total) D3173 1.45 wt. % -- -- Ash D3174 0.829 wt. % 0.841 wt. % --
Volatile Matter D3175 7.15 wt. % 7.26 wt. % 7.32 wt. % Fixed Carbon
D3172 90.6 wt. % 91.9 wt. % 92.7 wt % Sulfur D3177 ND.sup..dagger.
ND ND Heat Value D5865 14,942 BTU/lb 15,162 BTU/lb 15,291 BTU/lb
Ultimate Analysis Moisture (total) D3173 1.45 wt. % -- -- Ash D3174
0.829 wt. % 0.841 wt. % -- Sulfur D3177 ND ND ND Carbon D5373 88.3
wt. % 89.6 wt. % 90.4 wt. % Hydrogen.sup..dagger-dbl. D5373 1.97
wt. % 2.00 wt. % 2.01 wt. % Nitrogen D5373 0.209 wt. % 0.212 wt. %
0.214 wt. % Oxygen.sup..dagger-dbl. D3176 7.19 wt. % 7.30 wt. %
7.36 wt. % .sup..dagger.ND: Sulfur content was less than or equal
to about 0.050 wt. % (as-received), less than or equal to about
0.051 wt. % (moisture-free), or less than or equal to about 0.052
wt. % (ash and moisture-free). .sup..dagger-dbl.Excluding
water.
Example 9
Production of a High Heat Value Biogenic Activated Carbon
Product
[0844] This example demonstrates production of a biogenic activated
carbon product having a high heat value.
[0845] A feedstock comprising red pine chips having an average
particle size of approximately 1-inch by 1/2 inches by 1/8 inches
was pyrolyzed according to the General Method of Example 6. The
reactor was heated to 550.degree. C. and the feedstock was
pyrolyzed with a residence time of 30 minutes. After cooling, the
resulting biogenic activated carbon product was analyzed according
to the methods described in Example 7. Results are shown in Table
8.
TABLE-US-00008 TABLE 8 Analysis of High Heat Value Biogenic
Activated Carbon Product. Ash Parameter ASTM Method As-Received
Moisture Free Moisture Free Proximate Analysis Moisture (total)
D3173 2.55 wt. % -- -- Ash D3174 1.52 wt. % 1.56 wt. % -- Volatile
Matter D3175 10.1 wt. % 10.4 wt. % 10.5 wt. % Fixed Carbon D3172
85.8 wt. % 88.1 wt. % 89.5 wt. % Sulfur D3177 ND.sup..dagger. ND ND
Heat Value D5865 14,792 BTU/lb 15,179 BTU/lb 15,420 BTU/lb Ultimate
Analysis Moisture (total) D3173 2.55 wt. % -- -- Ash D3174 1.52 wt.
% 1.56 wt. % -- Sulfur D3177 ND ND ND Carbon D5373 88.9 wt. % 91.2
wt. % 92.7 wt. % Hydrogen.sup..dagger-dbl. D5373 2.36 wt. % 2.42
wt. % 2.45 wt. % Nitrogen D5373 0.400 wt. % 0.410 wt. % 0.417 wt. %
Oxygen.sup..dagger-dbl. D3176 4.22 wt. % 4.33 wt. % 4.40 wt. %
ND.sup..dagger.: Sulfur content was less than or equal to about
0.050 wt. % (as-received), less than or equal to about 0.051 wt. %
(moisture-free), or less than or equal to about 0.052 wt. % (ash
and moisture-free). .sup..dagger-dbl.Excluding water.
Example 10
Production of a Biogenic Activated Carbon Product for Blending with
Met Coke
[0846] Biogenic activated carbon was prepared from milled
kiln-dried wood doweling substantially according to the General
Method of Example 6.
[0847] Blends of met coke (Sample ID No. SGS/427-1104014-001) with
2% and 5% of the biogenic activated carbon product were prepared by
mixing the met coke with the appropriate amount of biogenic
activated carbon product. Strength and reactivity values were
measured according to ASTM D5341 for the blends compared to met
coke alone are shown in Table 9 (values are the average of a
minimum of two tests per sample).
TABLE-US-00009 TABLE 9 CSR and CRI of Biogenic Activated Carbon
Product-Met Coke Blends. Amount of Biogenic Activated Carbon
Product CRI CSR 0 wt. % (baseline) 24.5% 62.8% 2 wt. % 25.7%
(+1.2%) 62.3% (-0.5%) 5 wt. % 28.0% (+3.5%) 61.2% (-1.6%)
Example 11
Production of an Enhanced Hot-Strength Biogenic Activated Carbon
Product
[0848] Red pine wood chips approximately sized
1''.times.1/2''.times.1/8'' were pyrolyzed according to the General
Method of Example 6 at 600.degree. C. with a residence time of 30
minutes. The resulting biogenic activated carbon product is
referred to as "Sample A."
[0849] Milled, kiln-dried wood doweling having a 11/8'' diameter
was cut into segments having a length of about 1.5 inches each. The
segments were pyrolyzed according to the General Method of Example
1 at 600.degree. C. with a residence time of 2 hours. The resulting
biogenic activated carbon product is referred to as "Sample B."
[0850] Samples A and B were each placed separately into quartz
tubes and heated at 1,100.degree. C. in the presence of CO.sub.2
gas for one hour. After one hour, Sample A had a CSR value of about
0%. After one hour, Sample B had a CSR value of 64.6%. These
results indicate that potential for increasing hot strength of a
biogenic coke replacement product and suitability for use as a
replacement for met coke in various metal production
applications.
Example 12
Preparation of Particularly Dimensioned Biogenic Activated Carbon
Product
[0851] As shown in Table 10 below, biogenic activated carbon
product having a particular shape and average dimension was
produced according to the General Method of Example 6.
TABLE-US-00010 TABLE 10 Properties of Particularly Dimensioned
Biogenic Activated Carbon Product. Fixed Initial Final Volume
Initial Final Mass Sample Carbon Volume Volume Change Mass Mass
Change Blocks 90 wt. % 3.15 in.sup.3 1.51 in.sup.3 -52% 22.77 g
4.91 g -78% Cylinders-1 80 wt. % 1.46 in.sup.3 0.64 in.sup.3 -56%
14.47 g 3.61 g -75% Cylinders-2 90 wt. % 1.46 in.sup.3 0.58
in.sup.3 -60% 14.47 g 3.60 g -75%
Example 13
Effect of Residence Time on Fixed Carbon Levels
[0852] The effect of residence time on fixed carbon levels in the
biogenic activated carbon product was investigated by dividing one
batch of feedstock into four groups of approximately equal mass
composed of pieces of feedstock of approximately equal particle
size. Each of the four groups was subjected to pyrolysis according
to the General Method of Example 6 at 350.degree. C. with residence
times of 0 minutes, 30 minutes, 60 minutes, and 120 minutes,
respectively. Fixed carbon content of each sample was determined by
ASTM D3172. Results are shown in Table 11 and corresponding FIG.
18.
TABLE-US-00011 TABLE 11 Effect of Residence Time on Fixed Carbon
Levels. Sample Residence Time Fixed Carbon Residence-1 0 minutes 17
wt. % Residence-2 30 minutes 50 wt. % Residence-3 60 minutes 66 wt.
% Residence-4 120 minutes 72 wt. %
Example 14
Effect of Pyrolysis Temperature on Fixed Carbon Levels
[0853] The effect of pyrolysis temperature on fixed carbon levels
in the biogenic activated carbon product was investigated by
dividing one batch of feedstock into five groups of approximately
equal mass composed of pieces of feedstock of approximately equal
particle size. Each of the five groups was subjected to pyrolysis
according to the General Method of Example 6 with a 30 minute
residence time. Fixed carbon content of each sample was determined
by ASTM D3172. Results are shown in Table 12 and corresponding FIG.
19.
TABLE-US-00012 TABLE 12 Effect of Residence Time on Fixed Carbon
Levels. Sample Prolysis Temp. Fixed Carbon Temperature-1
310.degree. C. 38 wt. % Temperature-2 370.degree. C. 58 wt. %
Temperature-3 400.degree. C. 64 wt. % Temperature-4 500.degree. C.
77 wt. % Temperature-5 600.degree. C. 83 wt. %
Example 15
Effect of Feedstock Particle Size on Fixed Carbon Levels
[0854] The effect of feedstock particle size on fixed carbon levels
in the biogenic activated carbon product was investigated by
pyrolyzing three groups of red pine biomass: sawdust (average
particle size of approximately 0.0625 inches), chips (average
particle size of approximately 1 inch by 1/2 inch by 1/8 inches),
and chunks (cylinders having a 11/8'' diameter and a length of
approximately 1.5 inches). Each of the three groups was subjected
to pyrolysis according to the General Method of Example 6 at
400.degree. C. for 30 minutes. Fixed carbon content of each sample
was determined by ASTM D3172. Results are shown in Table 13 and
corresponding FIG. 20.
TABLE-US-00013 TABLE 13 Effect of Residence Time on Fixed Carbon
Levels. Sample Average Particle Size Fixed Carbon Sawdust ~0.0625
inches 71 wt. % Chips ~1 inch .times. 1/2 inch .times. 64 wt. % 1/8
inch Chunks ~1.5'' lengths of 11/8'' 62 wt. % diameter
cylinders
Example 161
Effect of Oxygen Level During Pyrolysis on Mass Yield of Biogenic
Activated Carbon Product
[0855] This example demonstrates the effect of oxygen levels on the
mass yield of biogenic activated carbon product.
[0856] Two samples of hardwood sawdust (4.0 g) were each placed in
a quartz tube. The quartz tube was then placed into a tube furnace
(Lindberg Model 55035). The gas flow was set to 2,000 ccm. One
sample was exposed to 100% nitrogen atmosphere, while the other
sample was subjected to a gas flow comprising 96% nitrogen and 4%
oxygen. The furnace temperature was set to 290.degree. C. Upon
reaching 290.degree. C. (approximately 20 minutes), the temperature
was held at 290.degree. C. for 10 minutes, at which time the heat
source was shut off, and the tube and furnace allowed to cool for
10 minutes. The tubes were removed from the furnace (gas still
flowing at 2,000 ccm). Once the tubes and samples were cool enough
to process, the gases were shut off, and the pyrolyzed material
removed and weighed (Table 14).
TABLE-US-00014 TABLE 14 Effect of Oxygen Levels During Pyrolysis on
Mass Yield. Sample Atmosphere Mass Yield Atmosphere-1(a) 100%
Nitrogen 87.5% Atmosphere-2(a) 96% Nitrogen, 4% Oxygen 50.0%
Example 17
Effect of Oxygen Level During Pyrolysis on Fixed Carbon Content
Level and Heat Value of Biogenic Activated Carbon Product
[0857] The increase in fixed carbon content and heat value from the
use of a Carbon Recovery Unit ("CRU") is demonstrated.
[0858] Pyrolysis of hardwood sawdust according to Example 15 was
performed. A standard coconut shell charcoal ("CSC") tube (SKC Cat.
No. 226-09) was placed in the off-gas stream following a standard
midget impinger containing 10 mL of HPLC-grade water. Increases in
fixed carbon levels and heat value were compared to a CSC tube that
had not been exposed to any off-gases (Table 15, ash and
moisture-free data).
TABLE-US-00015 TABLE 15 Increase in Fixed Carbon Content and Heat
Value as a Function of Oxygen Content During Pyrolysis. Increase in
Increase Carbon in Heat Sample Atmosphere Content Value
Atmosphere-1(b) 100% Nitrogen +3.2% +567 BTU/lb (+4.0%)
Atmosphere-2(b) 96% Nitrogen, 4% +1.6% +928 BTU/lb Oxygen
(+6.5%)
[0859] The results of Examples 16 and 17 demonstrate the benefits
of maintaining a near-zero oxygen atmosphere to on mass yield and
commercial value of the disclosed pyrolyzation process. Using the
off-gases from these two experiments it was also possible to
demonstrate that the BTU-laden gases exiting the process can be
captured for the purpose of enhancing the BTU content and/or carbon
content, of a carbon substrate (coal, coke, activated carbon,
carbon).
Example 18
Effect of Heated Nitrogen on Fixed Carbon Content of a Biogenic
Activated Carbon Product
[0860] This example demonstrates the effect of introducing heated
nitrogen gas to the biomass processing unit.
[0861] Production of biogenic activated carbon product using a
biomass consisting of red pine wood chips having a typical
dimension of 1 inch by 1/2 inches by 1/8 inches was performed
according to the General Method of Example 6 with a four-zone heat
pilot-scale reactor at 350.degree. C. In the first run, nitrogen
was introduced at ambient temperature. In a second run, which was
performed immediately after the first run in order to minimize
variation in other parameters, nitrogen was preheated to
300.degree. C. before injection into the pyrolysis zone. In each
case, the nitrogen flow rate was 1.2 cubic feet per minute, and the
biomass was processed for 30 minutes.
[0862] Fixed carbon content was measured on a dry, ash-free basis
according to ASTM D3172 for each run (Table 16).
TABLE-US-00016 TABLE 16 Effect of Nitrogen Temperature on Fixed
Carbon Content of a Biogenic Activated Carbon Product. Sample
Nitrogen Temperature Fixed Carbon Content Atmosphere-1(c) Ambient
51.7% Atmosphere-2(c) 300.degree. C. 55.3%
[0863] These test results demonstrate a 7.0% increase
[(100)(55.3%-51.7%)/55.3%] in the fixed carbon content of the
biogenic activated carbon product carbonized product by utilizing
pre-heated nitrogen.
Example 19
Improvement of Mass Yield by Pretreatment of Biomass
[0864] This example demonstrates the production of a biogenic
activated carbon product having an additive, namely iron(II)
bromide.
[0865] An aqueous solution of iron(II) bromide hydrate was created
by mixing 72.6 grams of iron(II) bromide hydrate into 1 gallon of
water (e.g., 1.0% bromine aqueous solution). This solution was
added to 5.23 pounds (2.37 kg) of air-dried (12% moisture content)
red pine wood chips. Each wood chip was approximately
1''.times.1/2''.times.1/8''.
[0866] The container of wood chips and solution was sealed with a
water tight lid. The contents were mixed periodically over the
course of approximately four hours by tipping and rolling the
container and contents. The wood chips and solution were kept
sealed overnight to allow for saturation of the wood chips with the
solution.
[0867] Thereafter, the contents were transferred to an open
water-proof tub and allowed to air dry for several hours, with
periodic mixing until all free liquid had been absorbed by the wood
chips or evaporated. The contents were transferred to an air-dryer
and allowed to dry overnight.
[0868] The pretreated, air-dried wood chips were verified to have
12% moisture content. The mass of the pretreated, air dried wood
chips was determined to be 5.25 lbs (2.38 kg). The contents were
transferred to a pyrolysis reactor with nitrogen gas preheated to
300.degree. C. with a gas flow rate of 0.4 cubic feet per minute.
Pyrolysis occurred at 370.degree. C. for 30 minutes.
[0869] The finished product was removed from the reactor at a
temperature of less than or equal to about 100.degree. C. Upon
reaching room temperature (approximately 23.degree. C.), the
finished product had a mass of 2.5 pounds (1.14 kg), indicating a
mass yield of 47.6% based upon feedstock mass (e.g., the mass
contribution of the pretreatment additive was subtracted) at 12%
moisture content. On a dry basis (correcting out the 12% moisture
and the mass contribution of the pretreatment additive), the mass
yield was 54.1%. As shown in Table 17 below, this represents a
28-39% increase in mass yield over untreated wood chips processed
under the same conditions.
TABLE-US-00017 TABLE 17 Pretreatment of Biomass with 1.0% Aqueous
Iron(II) Bromide Increases Mass Yield. Mass Yield Mass Yield
Pretreatment (12% Moisture) (Dry Basis) None 34.3% 39.0% None 35.4%
40.2% None 37.2% 42.2% Average (No Pretreatment) 35.6% 40.5%
Iron(II) Bromide 47.6% 54.1% % INCREASE +33.7% +33.6%
[0870] These data indicate a significant improvement in the mass
yield for wood chips treated with an iron (II) bromide solution
prior to pyrolytic processing.
Example 20
Enhanced Activation Through Feedstock Enhancement
[0871] This example demonstrates the positive benefits of
recapturing gas-phase carbonaceous species onto a pre-carbonized
substrate prior to a subsequent activation step.
[0872] Pre-carbonized feedstock (carbonized at 370.degree. C.) was
utilized. In a first experiment, this material was pyrolyzed
(activated, thermally treated) without passing the pyrolysis
off-gases through the feedstock. The maximum achieved Iodine Number
in this configuration was 909.
[0873] In a second experiment, this same substrate was utilized as
a gas-phase carbonaceous capture material. In this mode, the
maximum Iodine Number was recorded as 950.
[0874] These results are consistent with multiple experiments
executed at pilot scale using both pre-carbonized feedstock
substrate, and feedstock that has not been pre-carbonized.
[0875] All publications, patents, and patent applications cited in
this specification are herein incorporated by reference in their
entirety as if each publication, patent, or patent application were
specifically and individually put forth herein.
[0876] Where methods and steps described above indicate certain
events occurring in certain order, those of ordinary skill in the
art will recognize that the ordering of certain steps may be
modified and that such modifications are in accordance with the
variations of the disclosure. Additionally, certain of the steps
may be performed concurrently in a parallel process when possible,
or performed sequentially.
* * * * *