U.S. patent application number 14/945336 was filed with the patent office on 2016-05-26 for carbonized component-based fuel pellet.
This patent application is currently assigned to Washington State University. The applicant listed for this patent is TerraPower, LLC, Washington State University. Invention is credited to Karl Englund, Joshua C. Walter.
Application Number | 20160145519 14/945336 |
Document ID | / |
Family ID | 56009568 |
Filed Date | 2016-05-26 |
United States Patent
Application |
20160145519 |
Kind Code |
A1 |
Walter; Joshua C. ; et
al. |
May 26, 2016 |
CARBONIZED COMPONENT-BASED FUEL PELLET
Abstract
With the rapid increase in the price of fossil fuels and growing
concerns over climate change, the demand for renewable energy
sources continues to increase. Densified biomass fuels are an
alternative, renewable energy source that is becoming increasingly
popular. A densified biomass with increased and controllable energy
density is needed. Various embodiments of densified biomass and
process to manufacture are taught herein.
Inventors: |
Walter; Joshua C.;
(Kirkland, WA) ; Englund; Karl; (Moscow,
ID) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TerraPower, LLC
Washington State University |
Bellevue
Pullman |
WA
WA |
US
US |
|
|
Assignee: |
Washington State University
Pullman
WA
TerraPower, LLC
Bellevue
WA
|
Family ID: |
56009568 |
Appl. No.: |
14/945336 |
Filed: |
November 18, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62082354 |
Nov 20, 2014 |
|
|
|
Current U.S.
Class: |
44/553 ; 44/589;
44/590 |
Current CPC
Class: |
C10L 2290/28 20130101;
C10L 2290/06 20130101; Y02E 50/30 20130101; C10L 5/14 20130101;
C10L 5/44 20130101; C10L 2200/0438 20130101; C10L 5/447 20130101;
Y02E 50/10 20130101; C10L 2290/24 20130101; C10L 5/363 20130101;
C10L 5/146 20130101; C10L 2290/30 20130101; C10L 5/442 20130101;
C10L 2200/0469 20130101; C10L 2200/0484 20130101; C10L 2250/04
20130101 |
International
Class: |
C10L 5/44 20060101
C10L005/44; C10L 5/36 20060101 C10L005/36; C10L 5/14 20060101
C10L005/14 |
Claims
1. A process for manufacturing a densified biomass having an energy
density of greater than 8000 BTU/lb. comprising the steps of: a)
combining a carbonized component and at least one other component
chosen from the group consisting of biomass, lubricant, and binder
to form a combined carbonized component; and b) densifying the
combined carbonized mixture to form the densified biomass.
2. The process according to claim 1 where the combined carbonized
mixture, based on dry weight, is 10-80% carbonized component, 0-80%
biomass, 0-30% binder, 0-20% lubricant.
3. The process according to claim 1 where the combined carbonized
mixture, based on dry weight, is 10-40% carbonized component,
50-80% biomass, and 0-5% binder, and 0-5% lubricant.
4. The process according to claim 1 where the carbonized mixture,
based on dry weight, is 10-40% carbonized component, 50-80%
biomass, and 5% binder, and 5% lubricant.
5. The process according to claim 1 where the combined carbonized
mixture includes the carbonized component and the biomass.
6. The process according to claim 5 where the biomass is comprised
of both woody type and non-woody type biomasses.
7. The process according to claim 1 where the combined carbonized
mixture includes the carbonized component and the binder.
8. The process according to claim 7 where the combined carbonized
mixture, based on dry weight, is 80-90% carbonized component and
0-20% binder.
9. The process according to claim 7 where the binder includes at
least one chosen from a bio-polymer or non-bio polymer.
10. The process according to claim 9 where the binder includes high
density polyethylene.
11. The process according to claim 7 where the binder includes a
hydrophobic polymer.
12. The process according to claim 1 where the combined carbonized
component includes the carbonized component and the lubricant, the
lubricant is at least one chosen from the group consisting of
bio-oils, petro-based oils, and synthetic lubricant.
13. The process according to claim 12 where the lubricant includes
at least one bio-oil.
14. The process according to claim 1 where the lubricant includes a
hydrophobic lubricant.
15. The process according to claim 1 where the carbonized component
includes a carbonized component derived from a second biomass that
has a low lignin content.
16. The process according to claim 1, where the combined carbonized
component includes the carbonized component and a biomass.
17. The process according to claim 16, where the second biomass is
the same type as the biomass.
18. The process according to claim 17, where the second biomass is
the same species as the biomass.
19. The process according to claim 16 where the biomass is woody
type, non-woody type, or a combination thereof.
20. The process according to claim 1 where the carbonized component
is an organic substance converted into carbon or carbon-containing
residue.
21. The process according to claim 1 where densifying includes
pelletization.
22. The process according to claim 1 further comprising drying the
combined carbonized mixture prior to densifying.
23. The process according to claim 1 further comprising applying a
second lubricant to the densified biomass after densification.
24. The process according to claim 1 further comprising applying a
second binder to the densified biomass after densification.
25. A densified biomass having an energy density of greater than
8000 BTU/lb. comprising the steps of: a) mixing a carbonized
component and at least one other component chosen from the group
consisting of biomass, lubricant, and binder to form a combined
carbonized mixture; i) where the carbonized component includes
biochar derived from a second biomass of a woody type; ii) where
the biomass includes woody biomass; iii) where the lubricant
includes bio-oil; iv) where the binder includes high density
polyethylene. b) densifying the combined carbonized mixture into
the densified biomass; c) applying a hydrophobic component to the
densified biomass.
26. The densified biomass according to claim 25 where the combined
carbonized mixture, based on dry weight, is 10-80% carbonized
component, 0-80% biomass, 0-30% binder, 0-20% lubricant.
27. The densified biomass according to claim 25 where the combined
carbonized mixture, based on dry weight, is 10-40% carbonized
component, 50-80% biomass, and 0-5% binder, and 0-5% lubricant.
28. The densified biomass according to claim 25 where the
carbonized mixture, based on dry weight, is 10-40% carbonized
component, 50-80% biomass, and 5% binder, and 5% lubricant.
29. The densified biomass according to claim 25 where the combined
carbonized mixture includes the carbonized component and the
biomass.
30. The densified biomass according to claim 29 where the combined
carbonized mixture includes the carbonized component and the
binder.
31. The densified biomass according to claim 31 where the combined
carbonized mixture, based on dry weight, is 80-90% carbonized
component and 0-20% binder.
32. The densified biomass according to claim 25 where combined
carbonized mixture includes the carbonized component, the biomass
and the lubricant, the lubricant.
33. The densified biomass according to claim 39, where the second
biomass is of the same species as the biomass.
34. The densified biomass according to claim 26 where the
densifying includes pellitization.
35. The densified biomass according to claim 26 further comprising
creating a selected moisture content in the combined carbonized
mixture prior to densification.
36. The densified biomass according to claim 35, where creating a
selected moisture content includes adding moisture to the combined
carbonized mixture.
37. The densified biomass according to claim 35, where creating the
selected moisture content includes drying the combined carbonized
component.
38. The densified biomass according to claim 26 where a second
lubricant is applied to the densified biomass after densification
and includes a polymer.
39. The densified biomass according to claim 26 where a second
binder is applied to the densified biomass after densification.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 62/082,354 filed on Nov. 20, 2014 and incorporated
herein, in its entirety, by reference.
BACKGROUND
[0002] With the rapid increase in the price of fossil fuels and
growing concerns over climate change, the demand for renewable
energy sources continues to increase. Densified biomass fuels are
an alternative renewable energy source.
SUMMARY OF THE INVENTION
[0003] A carbonized component can be combined with at least one
other component chosen from biomass, a lubricant, and a binder, and
compressed into a densified biomass fuel. In one example, the
carbonized component can be combined with a biomass and one or both
of a lubricant and a binder. The carbonized component may be
derived from the same or different type and/or species of biomass
as the biomass component. The resulting densified biomass may have
an energy density greater than 8000 BTU/lb. The addition of a
carbonized component increases the energy density of densified
biomass fuels; and the addition of selected amounts and/or types of
carbonized components allows the energy density can be more
accurately predicted and controlled in manufacture. Conversion of a
wide variety of biomass to a carbonized component may allow a
greater variety of feedstocks to be used as a densified biomass
fuel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Other features and advantages of the present invention will
become apparent in the following detailed descriptions of the
preferred embodiment with reference to the accompanying drawings,
of which:
[0005] FIG. 1A shows an example process to make densified
biomass;
[0006] FIG. 1B shows an example process to make a densified
biomass;
[0007] FIG. 2A shows an example particle size distribution for the
screened sawdust biomass;
[0008] FIG. 2B shows an example particle size distribution for the
carbonized component; and
[0009] FIG. 3 shows an example biochar carbonized component content
percentage against the energy density heat of combustion value;
[0010] FIG. 4 shows an example process to make densified
biomass.
DETAILED DESCRIPTION OF THE INVENTION
[0011] In the following detailed description, reference is made to
the accompanying drawings, which form a part hereof. In the
drawings, the use of similar or the same symbols in different
drawings typically indicate similar or identical items, unless
context dictates otherwise. The illustrative embodiments described
in the detailed description, drawings, and claims are not meant to
be limiting. Other embodiments may be utilized, and other changes
may be made, without departing from the spirit or scope of the
subject matter presented here. One skilled in the art will
recognize that the herein described components (e.g., operations),
devices, objects, and the discussion accompanying them are used as
examples for the sake of conceptual clarity and that various
configuration modifications are contemplated. Consequently, as used
herein, the specific exemplars set forth and the accompanying
discussion are intended to be representative of their more general
classes. In general, use of any specific exemplar is intended to be
representative of its class, and the non-inclusion of specific
components (e.g., operations), devices, and objects should not be
taken as limiting.
[0012] The present application may use formal outline headings for
clarity of presentation. However, it is to be understood that the
outline headings are for presentation purposes, and that different
types of subject matter may be discussed throughout the application
(e.g., device(s)/structure(s) may be described under
process(es)/operations heading(s) and/or process(es)/operations may
be discussed under structure(s)/process(es) headings; and/or
descriptions of single topics may span two or more topic headings).
Hence, the use of the formal outline headings is not intended to be
in any way limiting. By way of overview, embodiments provide
improved densified biomass fuel and methods for manufacture.
[0013] Densified biomass fuels are typically made by the
densification of woody or non-woody biomass. The densification
process allows for non-uniform biomass material to be densified
into a generally geometrically uniform product that can be handled,
transported, and used in mostly standardized heating units, such as
pellet stoves or industrial boilers. Densification may be
accomplished by a cuber, briquetter, pellet mill, or extruder, for
example. The requirements of a particular combustion system (pellet
stove or industrial boilers), components of the combined carbonized
mixture, manufacturing availability, costs, etc. may be factors in
determining the appropriateness of determine the device used for
densification.
[0014] The amount of energy a densified biomass releases, or its
energy density, was previously dependent on the type of biomass
material used. For example, woody biomass, such as Abies Grandis,
commonly known as white fir, has a greater energy density than
pellets produced from non-woody forms of biomass. Depending on the
biomass, densification process, and various environmental factors,
it has been difficult to predict and manufacture, with any kind of
certainty, the energy density of a single piece of densified
biomass or a package of densified biomass having a plurality of
densified biomass pieces, for example, or at least specify a minim
energy density of the single piece or package of densified biomass.
Although densification processes are well known, most densified
biomass fuels lack the energy density and/or
predictability/uniformity that some combustion systems or user
applications require. Additionally, currently manufactured
densified biomass fuels are not resistant to moisture and lose
their integrity when exposed to rain or dew. Consequently,
densified biomass fuels need to be stored and transported in dry
facilities thereby increasing the cost of manufacture and use.
Also, for densified biomass fuels to be practical to use in
residential or commercial combustion systems, a higher energy
density, as compared to that of a standard pressed wood pellet, for
example, is needed as well as predictable and/or minimum energy
density.
[0015] Mixing a carbonized component to raw or dried biomass
feedstock prior to densification will increase the energy density
of densified biomass fuel as compared to standard pressed biomass,
such as wood, pellets. The energy value can be determined and then
controllably altered through the addition of a carbonized component
which is of higher energy density per unit mass relative to typical
raw biomass. Biomass feedstock may be wood, agricultural crops,
organic waste (e.g. residential, commercial, and/or agricultural
waste such as straw, corn cobs, fruit pomace, yard waste, etc.), or
other lingo-cellulosic materials, individually or in combination.
The biomass feedstock may be in particle form and/or shredded form
or combination thereof or in any other appropriate form. The
biomass may be of a single type (e.g., agricultural waste, etc.) or
of a single species (e.g. straw) for simplicity in sourcing but may
also be provided as combination two or more multiple types or
species of biomass (e.g., wood and non-wood, or straw and grass). A
carbonized component may be an organic substance that has been
converted into carbon or a carbon-containing residue through any
appropriate process such as pyrolysis, destructive distillation, or
other means obtaining the same or similar results. For example,
biochar is a solid material obtained from the carbonization,
through pyrolysis or heating in a low/no oxygen environment, of
biomass. Coal is another example of a carbonized component. Coke,
coal gas, gas carbon, coal tar, Buckministerfullerene, ammonia
liquor, and "coal oil" are examples of commercially available
carbonized components that are obtained from the destructive
distillation of coal. It will be appreciated that other forms of
carbon may also be used as a carbonized component as desired for a
particular application. The carbonized component may be of a single
type (e.g., biomass derivative or non-biomass, wood or non-wood) or
may be a combination. The carbonized component may include a single
or multiple types of carbonized components where the species may
include the type of biomass derivative (e.g., white fir wood). The
carbonized component may be derived from the same or different type
or even species of biomass as the biomass components (e.g., the
carbonized component may be derived from wood products and the
biomass be of the wood type, the carbonized component may be
derived from white fir and the biomass may include white fir,
etc.). The combination of a biomass feedstock and carbonized
component with an optional binder and/or lubricant can result in a
densified biomass which is structurally stable with heating values
(energy density) (HHV) in the range of 7,500-11,000 BTU/lb.
[0016] Referring generally to the FIGS. 1A and 1B, in various
embodiments, a carbonized component 10 can be combined in a mixer
20 or densifier 22 with at least one other component chosen from
biomass 12, a lubricant 14, and a binder 16 to form a combined
carbonized mixture 24. The biomass 12 can be a single type of
biomass, e.g., a particular type of wood such as white fir, or a
combination of various types of biomass, woody or non-wood.
Similarly, the lubricant 14 can be any suitable lubricant or
combination of lubricants; and the binder 16 can be any suitable
single type of binder or combination of binders. The combined
carbonized mixture 24 can be compressed in a densifier 22 into a
densified biomass fuel 18. Densification of the combined carbonized
mixture 24 in the densifier 22 may be accomplished by any
appropriate equipment and/or process such as a cuber, pellet mill,
or extruder, for example. In some examples, the biomass and/or
combined carbonized component, biomass, lubricant, and/or binder
can be dried prior to densification. The drying process can be
accomplished in a dryer, oven, natural ambient conditions, etc. In
various embodiments, moisture in the form of liquid water or steam,
for example, may be added to the carbonized component 10 and at
least one other component chosen from biomass 12, lubricant 14, and
binder 16. The moisture can be added to any one or more components
(e.g., the carbonized component, the biomass, the binder, and/or
the lubricant) before mixing into the combined carbonized mixture,
or may be added to the combined carbonized mixture, or may
additionally or alternatively added to the combined carbonized
mixture but before densification. The additional moisture may
promote even heating of the combined carbonized mixture 24 during
the densification process.
[0017] During densification, heating of the combined carbonized
mixture 24 may cause softening of lignin and hemicellulose. Upon
cooling, the lignin hardens and structurally stabilizes the
densified biomass 18. Depending upon the biomass 12 used in the
combination carbonized mixture 24, densified biomass 18 may have
higher energy densities that those created using existing biomass
alone without a carbonized component.
[0018] In various embodiments, the binder 16 may be included in the
combined carbonized mixture 24 to enhance a biomass 12 which
contains small amounts of lignin. For example, some biomass
feedstock component 12 may include a lignin content of only 10-20%
wt lignin (e.g., grasses) which may lead to structural instability
of the densified biomass or require specialized processing or
handling. The binder 16 may be any suitable binder, including
without limitation, biopolymers or manmade polymers. Biopolymers
may include, for example, corn starch, cotton, etc. Binders may
also be derived from non-bio sources (e.g., man-made); for example,
a plastic such as high density polyethylene (HDPE). The HDPE may be
obtained from refuse such as material destined for a landfills
(e.g., recycled or re-used) or may be manufactured. The binder 16
may partially break down during heating in the densifier 22, and
may harden and structurally stabilize densified biomass 18. In
various embodiments, the binder 16 used may be hydrophobic which in
one example includes a polymer.
[0019] In various embodiments, a carbonized component 10 may be
mixed with only a binder 16 before densification 22. In such
embodiments, the ratio of carbonized component 10 to binder 16 may
be low in order to form a more structurally densified biomass 18.
In some embodiments of densified biomass 18, based on dry weight
mass, the combined carbonized mixture 24 may include 80-90%
carbonized component and 0-20% binder 16 and in some cases may be
5% binder 16. A binder may be advantageous for mixing in a combined
carbonized mixture 24 with higher ratios of carbonized component 10
compared to biomass 12 to form a densified biomass 18 that is
structurally stable (e.g., a durability index of a selected value).
The binder 16 may be added in a similar fashion as the carbonized
component to adjust and/or increase the energy density of the
densified biomass 18. Binders 16 may be used within the mixer 20
and/or applied after the densifier 22 to fill pores that may occur
in the final densified biomass (e.g. pellet).
[0020] Lubricant 14 may be any appropriate lubricant including any
one or more of water or oil based which may include, vegetable oil,
or other bio-oils (including bio-oils from pyrolysis of bio-based
materials, naturally derived oils, etc.), petro-chemical based
oils, synthetic lubricants derived from petroleum or natural gas
origins (such as olefins, esters, glycols, paraffins, etc.), etc.
Lubricants 14 derived from bio-oils may also serve as a binder 16
due to the presence of reducible hydrocarbons and oxygenates. The
lubricant 14 may improve flow of the combined carbonized mixture 24
through the densification process, such as improving flow of the
mixture into die for formation of the densified biomass 18 (e.g.,
pucks, briquettes, logs and/or pellets) in the densifier 22. The
lubricant may also act to conduct heat evenly throughout the
mixture during the densification process.
[0021] Some lubricants 14, such as oils, may have hydrophobic
properties. In various embodiments, the addition of oil as a
lubricant 14 additionally decreases the roughness of densified
biomass creating an enhanced barrier to moisture. Oils may be added
to the carbonized component 10 in the mixer 20, as discussed above,
or applied (e.g., misted, sprayed, coated, etc.) onto the surface
of densified biomass 18 after leaving the densifier 22 or any other
suitable time afterward. In various embodiments, polymers which dry
may also be applied as appropriate onto densified biomass 18 after
the densifier 22. Exemplary drying polymers include alcohol soluble
polymers like ethylene glycol or poly vinyl alcohol.
[0022] Mixing biomass 12 with a carbonized component 10 has several
advantages including a higher energy density. Carbon has an energy
density of .about.14,500 BTU/lb. Biochar or other carbonized
components 10 can be formed with energy densities ranging from
5,100 to 19,000 BTU/lb. Dried wood (an example of a biomass 12) has
an energy density of .about.8,000 BTU/lb. Mixing a carbonized
component 10 that has an energy density greater than 8,000 BTU/lb
with the biomass 12 containing wood during or prior to
densification may lead to a densified biomass 18 with a higher
overall energy density than if made from wood (or other biomass)
alone. Mixing biomass 12 with a carbonized component 10 produced
from the same biomass 12 may produce a densified fuel pellet with
an energy density (by mass and volume) higher than that of a pellet
produced only from the biomass alone. For example, the carbonized
component 10 can be produced from a selected biomass 12 through an
appropriate carbonization process (converted into carbon or a
carbon-containing residue through any appropriate process such as
pyrolysis, destructive distillation, or other means obtaining the
same or similar result) and the carbonized component 10 can then be
combined in the mixer 20 with a biomass 12 of the same type and may
include one or more of a lubricant 14 and/or binder 16.
[0023] In various embodiments, a first biomass 12a with low lignin
content may be carbonized into a carbonized component 10 and mixed
with a second type of biomass 12b with a higher lignin content than
the first biomass 12a, yielding a densified biomass 18 that has an
energy density which is larger than the energy density of the first
biomass 12a and second biomass 12b together. Biomass feedstock with
low lignin content includes grasses, agricultural crops and
agricultural residues, food wastes, amongst others.
[0024] In various embodiments, the ratio of the carbonized
components to at least one component chosen from biomass,
lubricant, and binder may be adjusted to provide densified biomass
with an energy content or energy density at or above a preselected
value. In various embodiments, the mass density of the densified
form may be greater than 0.8 g/cc., the mass density may be greater
than 1 g/cc., the mass density may be greater than 1.2 g/cc. In
various embodiments the energy density may be greater than 8000
BTU/lb., the mass energy density may be greater than 9000 BTU/lb.,
and/or the mass energy density may be greater than 10,000
BTU/lb.
[0025] In one embodiment, a carbonized component 10 having an
energy density of 14,500 BTU/lb maybe mixed with biomass of 8,000
BTU/lb (such as some woody biomass) at a ratio of 25% biochar to
75% woody biomass to produce a densified biomass having 9,625
BTU/lb. The ratio of carbonized component 10 to biomass 12 may be
adjusted to account for the type of biomass being used (e.g.,
average energy density of the biomass, average desired energy
density of the densified biomass, biomass lignin content, etc.),
the desired durability of the densified biomass, the final
combustion system requirements, etc.
[0026] In various embodiments, the ratio of carbonized component 10
to at least one component chosen from biomass 12, a lubricant 14,
and a binder 16 may be adjusted to provide densified biomass 18
having a predetermined or exceeding a predetermined threshold
grindability rating (such as the Hargrove Grindability Index or
other appropriate grindability rating). In one exemplary
embodiment, the densified biomass 18 exhibits a grindability rating
resulting in less than a 100-micron average particle size. In
another exemplary embodiment, the densified biomass 18 exhibits a
grindability rating resulting in less than a 75-micron average
particle size. In another exemplary embodiment, the densified
biomass 18 exhibits a grindability rating resulting in less than a
50-micron average particle size. Generally increasing the ratio of
carbonized component to biomass and/or lubricant and binder can
increase the grindability as char can typically be brittle. The
densified biomass may be formed using a combination of carbonized
component and at least one of a biomass, lubricant and binder to
have a similar grindability index as coal under the Hardgroves
Grindability index (e.g. ball milling a source material until a
percentage of the source material can be filtered through a
specified mesh size) or any other grindability rating or standard,
and/or a similar particle size distribution as coal or any other
selected product or Hardgroves index which may be selected to match
expectations and/or requirements of existing or anticipated
combustion or processing equipment. Some existing coal plants have
a typical coal particle size distribution of approximately 75
micrometers with a range of 40-250 micrometers.
[0027] The ratio of the carbonized component 10 to at least one
component chosen from biomass 12, lubricant 14, and binder 16 may
be adjusted to provide densified biomass 18 that is resistant to
moisture. Some carbonized components such as biochar is less
susceptible to absorbing moisture than some forms of biomass
feedstock. In various embodiments, a larger concentration of a
carbonized component 10 as compared to biomass 12 may make
densified biomass less susceptible to the effects of moisture. As
noted above, addition of some types of lubricants and/or binders
may also increase the moisture resistance of the densified biomass
18.
[0028] In some embodiments of densified biomass, based on dry
weight mass, the combined carbonized mixture 24 may include 10-80%
carbonized component, 10-80% biomass, 0-30% binder, 0-20%
lubricant. In one embodiment, 10-40% carbonized component, 50-80%
biomass, 5% binder, and 5% lubricant may be used. The densified
biomass 18 may be densified using a densifier 22 which may include
conventional pelleting processes via ring or flat die
configuration, briquetting, and/or extrusion (screw- or ram-based
systems) or any other appropriate method and/or equipment.
[0029] FIG. 4 illustrates an example method 400 of manufacturing a
densified biomass of which not all steps or acts will be required
and may be optionally included as appropriate. The biomass
component (if included in the combined carbonized mixture may be
appropriately sized 410 using any suitable technique, such as
screening, filtering, agitating, etc. The biomass may be dried 412
to a selected range or approximate water content using any
appropriate technique such as drying in ambient conditions,
furnace, heater, air flow, etc. The binder may be selected 414 to
augment the lignin content (or lack thereof) in the carbonized
component and/or the biomass. The lubricant may be selected 416 to
augment the manufacturing consistency of the combined carbonized
component for densification and/or potential benefits of moisture
control (hydrophobic qualities), etc. The carbonized component may
be selected and sized 418 using any appropriate technique such as
screening, filtering, agitating, etc. The carbonized component may
be optionally dried 420 using any appropriate technique such as
ambient or controlled conditions, air flow, heating, etc. The
carbonized component may be combined or mixed 422 with the biomass,
lubricant, and/or binder in selected quantities into a combined
carbonized mixture to achieve the desired densified biomass
stability, heat combustion qualities, and/or any other quality of
the densified biomass or resulting combustion system. The combined
carbonized mixture may be dried 424 using any suitable technique
including drying in ambient or controlled conditions, heater, air
flow, etc. The combined carbonized mixture may be densified 426
into a densified biomass using any suitable technique and equipment
such as pressing, extrusion, etc. and formed into any suitable form
such as pellets, pucks, etc.
[0030] Prior to densification 426, moisture in the form of liquid
water or steam, for example, may be added 435 to the combined
carbonized mixture. The moisture may be added in any suitable
technique such as spraying, flow, etc. The moisture may be added
and/or removed to achieve a combined carbonized mixture having the
desired and preselected water content. The preselected water
content may be approximately 10% by mass weight but may be less
than 31%. An optional binder (which may have hydrophobic qualities
and which may be different or the same as the binder if used in the
combined carbonized component) may be applied 430 to the densified
biomass and/or an optional lubricant (which may have hydrophobic
qualities and which may be the same as or different from the
lubricant if used in the combined carbonized mixture) may be
applied 432 to the densified biomass. If an optional binder and/or
lubricant is applied to 432 to the densified biomass, then the
densified biomass may be dried 428 using any suitable technique
such as drying in ambient or controlled conditions, heater, air
flow, etc. The densified biomass may then be combusted 434 in a
combustion system to generate heat and/or energy.
[0031] Potential forms of densified biomass 18 include pellets made
by mixing a carbon component 24, biomass feedstock 12, binder 16,
and lubricant 14; where the carbon component 24 is biochar (derived
from a woody biomass), the biomass feedstock 12 is sawdust obtained
from band mill sawdust residuals of Grand Fir, the binder 16 is a
powdered high density polyethylene ("HDPE") (MFI--0.3-0.5), and the
lubricant is canola oil. The weight percentages for some
embodiments are shown in Table 1 although it is to be appreciated
that other ratios and/or types of carbonized component, biomass
feedstock, lubricant, and/or binder may be used as appropriate.
TABLE-US-00001 TABLE 1 Example Formulations for the biochar energy
pellets Component Level (%) Component Run #1 Run #2 Run #3 Run #4
Run #5 Grand fir sawdust 90 80 70 60 50 Biochar 0 10 20 30 40
Canola oil 5 5 5 5 5 HDPE 5 5 5 5 5
[0032] The heat of combustion for each component in Table 1 and the
pellets manufactured at each "run" was determined utilizing a bomb
calorimeter. Testing guidelines prescribed by ASTM D5865-07, 2007,
Standard Test Method for Gross Calorific Value of Coal and Coke,
West Conshocken, Pa., ASTM Int'l, were followed with a sample size
of n=5.
[0033] Based upon sawdust residuals size and shape, sawdust
residuals may be appropriate biomass feedstocks 12 for making most
densified biomass 18 fuel pellets. However, to make a consistent
product, screening and drying the sawdust residuals (biomass 12)
may be desired. A mechanical classifier with a 0.375'' screen may
be used to separate out "overs" or larger particles, although it is
to be appreciated that other sizes any or screening methods may be
used as appropriate. The screened biomass 12 material may be
allowed to air dry in ambient conditions for 2 days (although it is
to be appreciated that other drying and/or times may be
appropriate) to a moisture content below 31% (between 23-31%)
before combination in the mixer with the carbonized component.
[0034] The particle size distribution for the screened sawdust
(biomass 12) and the carbonized component 10 are shown in FIGS. 2A
and 2B respectively. As shown in the example distribution of FIG.
2B, the carbonized component 10 may have a bimodal population of
particles, where there are significant amounts of large (+0.425 mm)
and fine (<0.106 mm) particles. As shown in the example
distribution of FIG. 2A, the biomass feedstock 12 (which in some
cases like here may be Grand Fir sawdust) particle size
distribution has a common bell-shaped curve of a normal
distribution. The screen sizes used to characterize the carbonized
component 10 may be much smaller than the screens used for the
biomass feedstock 12 to characterize the possibility or existence
of finer particles within the carbonized component. The biomass
feedstock Grand Fir sawdust may be allowed to dry using any
appropriate technique including furnace/oven, ambient conditions,
etc. The Grand Fir sawdust utilized in the combined carbonized
mixture 24 may have a moisture content range between 23-31%. The
carbonized component 10 moisture content is approximately 5.3%.
[0035] The heat of combustion (energy density in BTU/lb) for the
individual components and the final densified biomass 18 pellets of
Table 1 are shown in Tables 2A, 2B, and 3 respectively. The data in
Table 2A shows actual heat of combustion values of the components
prior to mixing or densifying and Table 2B shows the reference
values of heat combustion values of the components prior to mixing
or densifying. The Grand Fir wood biomass feedstock 12 has the
lowest heat of combustion while HDPE (binder 16) has the highest
heat of combustion.
TABLE-US-00002 TABLE 2A Actual Bomb calorimetric values for the
individual component prior to pelletization. Heat of Heat of Drying
combustion combustion Component Method (Btu/lb) (KJ/kg) Grand fir
sawdust (biomass) Oven dry 8,705 .+-. 40 20,246 .+-. 90 Biochar
(carbonized Over dry 12,738 .+-. 96 29,628 .+-. 223 component)
Canola oil (lubricant) N/A 17,236 .+-. 24 40,090 .+-. 57 HDPE
(binder) N/A 20,212 .+-. 82 47,014 .+-. 191
TABLE-US-00003 TABLE 3 Physical and calorimetric values for the
pelletized material. Formulation Moisture Content Pellet wt % (wt
%) Density Heat of combustion Run # Biochar Feedstock Pellets
(g/cm.sup.3) (Btu/lb) (KJ/kg) 1 0 14.2 .+-. 0.7 7.5 .+-. 0.06 1.25
.+-. 0.01 9,289 .+-. 57 21,605 .+-. 134 2 10 23.7 .+-. 0.1 5.8 .+-.
0.07 1.29 .+-. 0.02 9,782 .+-. 58 22,753 .+-. 135 3 20 18.3 .+-.
0.6 3.2 .+-. 0.09 1.29 .+-. 0.03 10,069 .+-. 43 23,419 .+-. 101 4
30 22.4 .+-. 0.1 3.1 .+-. 0.09 1.26 .+-. 0.02 10,460 .+-. 12 24,331
.+-. 27 5 40 13.9 .+-. 0.2 2.9 .+-. 0.10 1.32 .+-. 0.04 10,977 .+-.
61 25,532 .+-. 142
[0036] By using the Rule of Mixtures (ROM) in the following
equation, a summation of the weight fraction (WF) of each component
(i) and their component heat of combustion (HC) was used to predict
the composite pellet HC.
Predicted HC = i = 0 n WF i * HC i ##EQU00001##
[0037] The plot in FIG. 3 shows the increasing trend with the
addition of biochar (carbonized component 10) in the formulation.
The ROM shows a similar increasing trend. However, the overall
results show a higher predicted HC than the experimental results.
The likely explanation for this discrepancy is that the moisture
was removed during the test of the individual components (the wood
biomass and biochar carbonized component), whereas the densified
biomass pellet HC values were based upon as-is MCs in the range of
2.9-7.5% (Table 3). To validate the influence of moisture, the
pellets were oven-dried at 103.degree. C. for 24 hours and tested.
The experimental results of the dried pellets showed a higher
calorific value than the ROM at the lower char levels, followed by
a shift at the 20% char level. A similar shift was seen with the
undried pellets. Since this trend has been observed in both data
sets, the shift might be indicative of potential interactions or
slight chemical alterations of the pellet composite. The data
provides an assessment of the influence biochar carbonized
component may have on the combustion characteristics of wood-based
energy pellets.
[0038] The bomb calorimetry tests performed followed closely with
literature values and showed an increasing HC trend that one would
expect to observe with the addition of biochar. The ROM provided a
simply model to predict the combustion values with reasonable
accuracy, which will be a valuable asset for any future work and
valuable for creating a mixed biomass product with a minimum energy
value at or below a selected value.
TABLE-US-00004 TABLE 2B Reference values for the HC of the
individual components in the pellet formulation. Component HHV
(Btu/lb) HHV (kJ/kg) Grand fir 8,738 20,235 Biochar 5,086~19,003
11,830~44,200 Canola oil 17,102 39,780 HDPE 19,905 46,300
[0039] Although the present invention has been described in
connection with embodiments thereof, it will be appreciated by
those skilled in the art that additions, deletions, modifications,
and substitutions not specifically described may be made without
departure from the spirit and scope of the invention as defined in
the appended claims.
[0040] With respect to the use of substantially any plural and/or
singular terms herein, those having skill in the art can translate
from the plural to the singular and/or from the singular to the
plural as is appropriate to the context and/or application. The
various singular/plural permutations are not expressly set forth
herein for sake of clarity.
[0041] The herein described subject matter sometimes illustrates
different components contained within, or connected with, different
other components. It is to be understood that such depicted
architectures are merely exemplary, and that in fact many other
architectures may be implemented which achieve the same
functionality. In a conceptual sense, any arrangement of components
to achieve the same functionality is effectively "associated" such
that the desired functionality is achieved. Hence, any two
components herein combined to achieve a particular functionality
can be seen as "associated with" each other such that the desired
functionality is achieved, irrespective of architectures or
intermedial components. Likewise, any two components so associated
can also be viewed as being "operably connected", or "operably
coupled," to each other to achieve the desired functionality, and
any two components capable of being so associated can also be
viewed as being "operably couplable," to each other to achieve the
desired functionality. Specific examples of operably couplable
include but are not limited to physically mateable and/or
physically interacting components, and/or wirelessly interactable,
and/or wirelessly interacting components, and/or logically
interacting, and/or logically interactable components.
[0042] In some instances, one or more components may be referred to
herein as "configured to," "configured by," "configurable to,"
"operable/operative to," "adapted/adaptable," "able to,"
"conformable/conformed to," etc. Those skilled in the art will
recognize that such terms (e.g., "configured to") can generally
encompass active-state components and/or inactive-state components
and/or standby-state components, unless context requires
otherwise.
[0043] While particular aspects of the present subject matter
described herein have been shown and described, it will be apparent
to those skilled in the art that, based upon the teachings herein,
changes and modifications may be made without departing from the
subject matter described herein and its broader aspects and,
therefore, the appended claims are to encompass within their scope
all such changes and modifications as are within the true spirit
and scope of the subject matter described herein. It will be
understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the
appended claims) are generally intended as "open" terms (e.g., the
term "including" should be interpreted as "including but not
limited to," the term "having" should be interpreted as "having at
least," the term "includes" should be interpreted as "includes but
is not limited to," etc.). It will be further understood by those
within the art that if a specific number of an introduced claim
recitation is intended, such an intent will be explicitly recited
in the claim, and in the absence of such recitation no such intent
is present. For example, as an aid to understanding, the following
appended claims may contain usage of the introductory phrases "at
least one" and "one or more" to introduce claim recitations.
However, the use of such phrases should not be construed to imply
that the introduction of a claim recitation by the indefinite
articles "a" or "an" limits any particular claim containing such
introduced claim recitation to claims containing only one such
recitation, even when the same claim includes the introductory
phrases "one or more" or "at least one" and indefinite articles
such as "a" or "an" (e.g., "a" and/or "an" should typically be
interpreted to mean "at least one" or "one or more"); the same
holds true for the use of definite articles used to introduce claim
recitations. In addition, even if a specific number of an
introduced claim recitation is explicitly recited, those skilled in
the art will recognize that such recitation should typically be
interpreted to mean at least the recited number (e.g., the bare
recitation of "two recitations," without other modifiers, typically
means at least two recitations, or two or more recitations).
Furthermore, in those instances where a convention analogous to "at
least one of A, B, and C, etc." is used, in general such a
construction is intended in the sense one having skill in the art
would understand the convention (e.g., "a system having at least
one of A, B, and C" would include but not be limited to systems
that have A alone, B alone, C alone, A and B together, A and C
together, B and C together, and/or A, B, and C together, etc.). In
those instances where a convention analogous to "at least one of A,
B, or C, etc." is used, in general such a construction is intended
in the sense one having skill in the art would understand the
convention (e.g., "a system having at least one of A, B, or C"
would include but not be limited to systems that have A alone, B
alone, C alone, A and B together, A and C together, B and C
together, and/or A, B, and C together, etc.). It will be further
understood by those within the art that typically a disjunctive
word and/or phrase presenting two or more alternative terms,
whether in the description, claims, or drawings, should be
understood to contemplate the possibilities of including one of the
terms, either of the terms, or both terms unless context dictates
otherwise. For example, the phrase "A or B" will be typically
understood to include the possibilities of "A" or "B" or "A and
B."
[0044] With respect to the appended claims, those skilled in the
art will appreciate that recited operations therein may generally
be performed in any order. Also, although various operational flows
are presented in a sequence(s), it should be understood that the
various operations may be performed in other orders than those
which are illustrated, or may be performed concurrently. Examples
of such alternate orderings may include overlapping, interleaved,
interrupted, reordered, incremental, preparatory, supplemental,
simultaneous, reverse, or other variant orderings, unless context
dictates otherwise. Furthermore, terms like "responsive to,"
"related to," or other past-tense adjectives are generally not
intended to exclude such variants, unless context dictates
otherwise.
[0045] Those skilled in the art will appreciate that the foregoing
specific exemplary processes and/or devices and/or technologies are
representative of more general processes and/or devices and/or
technologies taught elsewhere herein, such as in the claims filed
herewith and/or elsewhere in the present application.
[0046] While various aspects and embodiments have been disclosed
herein, other aspects and embodiments will be apparent to those
skilled in the art. The various aspects and embodiments disclosed
herein are for purposes of illustration and are not intended to be
limiting, with the true scope and spirit being indicated by the
following claims.
* * * * *