U.S. patent application number 15/368900 was filed with the patent office on 2017-03-23 for sorbents for removal of mercury.
The applicant listed for this patent is CALGON CARBON CORPORATION. Invention is credited to Richard A. MIMNA, Walter G. TRAMPOSCH.
Application Number | 20170080402 15/368900 |
Document ID | / |
Family ID | 49715470 |
Filed Date | 2017-03-23 |
United States Patent
Application |
20170080402 |
Kind Code |
A1 |
TRAMPOSCH; Walter G. ; et
al. |
March 23, 2017 |
SORBENTS FOR REMOVAL OF MERCURY
Abstract
Methods and systems for reducing mercury emissions from fluid
streams are provided herein, as are adsorbent materials having high
volumetric iodine numbers.
Inventors: |
TRAMPOSCH; Walter G.; (Moon
Township, PA) ; MIMNA; Richard A.; (Oakdale,
PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CALGON CARBON CORPORATION |
Moon Township |
PA |
US |
|
|
Family ID: |
49715470 |
Appl. No.: |
15/368900 |
Filed: |
December 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13841315 |
Mar 15, 2013 |
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15368900 |
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61658258 |
Jun 11, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 2251/304 20130101;
B01D 2253/25 20130101; B01J 20/103 20130101; B01J 20/02 20130101;
B01J 20/041 20130101; B01J 20/18 20130101; B01J 20/12 20130101;
B01D 53/04 20130101; B01D 2258/0283 20130101; B01J 20/22 20130101;
B01D 53/64 20130101; B01J 20/20 20130101; B01J 20/28016 20130101;
B01J 20/043 20130101; B01D 2251/402 20130101; B01J 20/28004
20130101; B01D 2253/102 20130101; B01J 20/0288 20130101; B01D
2257/602 20130101; B01D 2251/404 20130101; B01J 20/046
20130101 |
International
Class: |
B01J 20/20 20060101
B01J020/20; B01J 20/28 20060101 B01J020/28; B01J 20/02 20060101
B01J020/02; B01D 53/04 20060101 B01D053/04; B01D 53/64 20060101
B01D053/64 |
Claims
1. A mercury adsorptive material comprising an adsorptive material
having a volumetric iodine number of greater than about 450
mg/cc.
2. The mercury adsorptive material of claim 1, wherein the
volumetric iodine number is about 500 mg/cc to about 650 mg/cc.
3. The mercury adsorptive material of claim 1, wherein the
volumetric iodine number is about 500 mg/cc to about 700 mg/cc.
4. The mercury adsorptive material of claim 1, wherein the
adsorptive material is selected from the group consisting of
activated carbon, reactivated carbon, graphite, graphene carbon
black, zeolite, silica, silica gel, clay, and combinations
thereof.
5. The mercury adsorptive material of claim 1, wherein the
adsorptive material is an activated carbon derived from coal.
6. The mercury adsorptive material of claim 1, wherein the
adsorptive material has a mean particle diameter (MPD) of about 1
.mu.m to about 30 .mu.m.
7. The mercury adsorptive material of claim 1, further comprising
one or more oxidizing agent.
8. The mercury adsorptive material of claim 7, wherein the one or
more oxidizing agent is selected from the group consisting of
chlorine, bromine, iodine, ammonium bromide, ammonium chloride,
calcium hypochlorite, calcium hypobromite, calcium hypoiodite,
calcium chloride, calcium bromide, calcium iodide, magnesium
chloride, magnesium bromide, magnesium iodide, sodium chloride,
sodium bromide, sodium iodide, potassium tri-chloride, potassium
tri-bromide, potassium tri-iodide, and combinations thereof.
9. The mercury adsorptive material of claim 7, wherein the one or
more oxidizing agent comprises about 5 wt. % to about 50 wt. % of a
total adsorptive material.
10. The mercury adsorptive material of claim 1, further comprising
one or more nitrogen source.
11. The mercury adsorptive material of claim 10, wherein the one or
more nitrogen source is selected from the group consisting of
ammonium containing compounds, ammonia containing compounds, amines
containing compounds, amides containing compounds, imines
containing compounds, quaternary ammonium containing compounds, and
combinations thereof.
12. The mercury adsorptive material of claim 10, wherein the one or
more nitrogen source is selected from the group consisting of
ammonium iodide, ammonium bromide, or ammonium chloride, amine
halides, a quaternary ammonium halides, and combinations
thereof.
13. The mercury adsorptive material of claim 10, wherein the one or
more nitrogen source comprises about 5 wt. % to about 50 wt. % of a
total adsorptive material.
14. The mercury adsorptive material of claim 1, further comprising
an alkaline agent.
15. The mercury adsorptive material of claim 14, wherein the
alkaline agent is selected from the group consisting of alkaline
agent may be calcium carbonate, calcium oxide, calcium hydroxide,
magnesium carbonate, magnesium hydroxide, magnesium oxide, sodium
carbonate, sodium bicarbonate, trisodium hydrogendicarbonate
dihydrate, and combinations thereof.
16. The mercury adsorptive material of claim 14, wherein the
alkaline agent is provided at a concentration of greater than or
equal to about 0.15 equivalents per 100 grams of absorptive
material.
17. A mercury adsorptive material comprising: an adsorptive
material having a volumetric iodine number of greater than about
450 mg/cc; one or more oxidizing agent; and one or more nitrogen
source.
18. The mercury adsorptive material of claim 17, wherein the
volumetric iodine number is about 500 mg/cc to about 650 mg/cc.
19. The mercury adsorptive material of claim 17, wherein the
volumetric iodine number is about 500 mg/cc to about 700 mg/cc.
20. The mercury adsorptive material of claim 17, wherein the
adsorptive material is selected from the group consisting of
activated carbon, reactivated carbon, graphite, graphene carbon
black, zeolite, silica, silica gel, clay, and combinations
thereof.
21. The mercury adsorptive material of claim 17, wherein the one or
more oxidizing agent is selected from the group consisting of
chlorine, bromine, iodine, ammonium bromide, ammonium chloride,
calcium hypochlorite, calcium hypobromite, calcium hypoiodite,
calcium chloride, calcium bromide, calcium iodide, magnesium
chloride, magnesium bromide, magnesium iodide, sodium chloride,
sodium bromide, sodium iodide, potassium tri-chloride, potassium
tri-bromide, potassium tri-iodide, and combinations thereof.
22. The mercury adsorptive material of claim 17, wherein the one or
more nitrogen source is selected from the group consisting of
ammonium iodide, ammonium bromide, or ammonium chloride, amine
halides, a quaternary ammonium halides, and combinations
thereof.
23. A mercury adsorptive material comprising: an adsorptive
material having a volumetric iodine number of greater than about
450 mg/cc; one or more oxidizing agent; and one or more alkaline
agent.
24. The mercury adsorptive material of claim 23, wherein the
volumetric iodine number is about 500 mg/cc to about 650 mg/cc.
25. The mercury adsorptive material of claim 23, wherein the
volumetric iodine number is about 500 mg/cc to about 700 mg/cc.
26. The mercury adsorptive material of claim 23, wherein the
adsorptive material is selected from the group consisting of
activated carbon, reactivated carbon, graphite, graphene carbon
black, zeolite, silica, silica gel, clay, and combinations
thereof.
27. The mercury adsorptive material of claim 23, wherein the one or
more oxidizing agent is selected from the group consisting of
chlorine, bromine, iodine, ammonium bromide, ammonium chloride,
calcium hypochlorite, calcium hypobromite, calcium hypoiodite,
calcium chloride, calcium bromide, calcium iodide, magnesium
chloride, magnesium bromide, magnesium iodide, sodium chloride,
sodium bromide, sodium iodide, potassium tri-chloride, potassium
tri-bromide, potassium tri-iodide, and combinations thereof.
28. The mercury adsorptive material of claim 23, wherein the
alkaline agent is selected from the group consisting of alkaline
agent may be calcium carbonate, calcium oxide, calcium hydroxide,
magnesium carbonate, magnesium hydroxide, magnesium oxide, sodium
carbonate, sodium bicarbonate, trisodium hydrogendicarbonate
dihydrate, and combinations thereof.
29. A system for removing mercury from flue gas, the system
comprising an adsorptive material having a volumetric iodine number
of greater than 450 mg/cc.
30. The system of claim 29, wherein the volumetric iodine number is
about 500 mg/cc to about 650 mg/cc.
31. The system of claim 29, wherein the volumetric iodine number is
about 500 mg/cc to about 700 mg/cc.
32. The system of claim 29, wherein the adsorptive material is
selected from the group consisting of activated carbon, reactivated
carbon, graphite, graphene carbon black, zeolite, silica, silica
gel, clay, and combinations thereof.
33. The system of claim 29, wherein the adsorptive material is an
activated carbon derived from coal.
34. The system of claim 29, wherein the adsorptive material has a
mean particle diameter (MPD) of about 1 .mu.m to about 30
.mu.m.
35. The system of claim 29, further comprising one or more
oxidizing agent.
36. The system of claim 35, wherein the one or more oxidizing agent
is selected from the group consisting of chlorine, bromine, iodine,
ammonium bromide, ammonium chloride, calcium hypochlorite, calcium
hypobromite, calcium hypoiodite, calcium chloride, calcium bromide,
calcium iodide, magnesium chloride, magnesium bromide, magnesium
iodide, sodium chloride, sodium bromide, sodium iodide, potassium
tri-chloride, potassium tri-bromide, potassium tri-iodide, and
combinations thereof.
37. The system of claim 35, wherein the one or more oxidizing agent
comprises about 5 wt. % to about 50 wt. % of a total adsorptive
material.
38. The system of claim 29, further comprising one or more nitrogen
source.
39. The system of claim 38, wherein the one or more nitrogen source
is selected from the group consisting of ammonium containing
compounds, ammonia containing compounds, amines containing
compounds, amides containing compounds, imines containing
compounds, quaternary ammonium containing compounds, and
combinations thereof.
40. The system of claim 38, wherein the one or more nitrogen source
is selected from the group consisting of ammonium iodide, ammonium
bromide, or ammonium chloride, amine halides, a quaternary ammonium
halides, and combinations thereof.
41. The system of claim 38, wherein the one or more nitrogen source
comprises about 5 wt. % to about 50 wt. % of a total adsorptive
material.
42. The system of claim 29, further comprising an alkaline
agent.
43. The system of claim 42, wherein the alkaline agent is selected
from the group consisting of alkaline agent may be calcium
carbonate, calcium oxide, calcium hydroxide, magnesium carbonate,
magnesium hydroxide, magnesium oxide, sodium carbonate, sodium
bicarbonate, trisodium hydrogendicarbonate dihydrate, and
combinations thereof.
44. The system of claim 42, wherein the alkaline agent is provided
at a concentration of greater than or equal to about 0.15
equivalents per 100 grams of absorptive material.
45. A method for mercury removal comprising: injecting an
adsorptive material having a volumetric iodine number of greater
than 450 mg/cc.
46. The method of claim 45, wherein the volumetric iodine number is
about 500 mg/cc to about 650 mg/cc.
47. The method of claim 45, wherein the volumetric iodine number is
about 500 mg/cc to about 700 mg/cc.
48. The method of claim 45, wherein the adsorptive material is
selected from the group consisting of activated carbon, reactivated
carbon, graphite, graphene carbon black, zeolite, silica, silica
gel, clay, and combinations thereof.
49. The method of claim 45, wherein the adsorptive material is an
activated carbon derived from coal.
50. The method of claim 45, wherein the adsorptive material has a
mean particle diameter (MPD) of about 1 .mu.m to about 30
.mu.m.
51. The method of claim 45, further comprising one or more
oxidizing agent.
52. The method of claim 51, wherein the one or more oxidizing agent
is selected from the group consisting of chlorine, bromine, iodine,
ammonium bromide, ammonium chloride, calcium hypochlorite, calcium
hypobromite, calcium hypoiodite, calcium chloride, calcium bromide,
calcium iodide, magnesium chloride, magnesium bromide, magnesium
iodide, sodium chloride, sodium bromide, sodium iodide, potassium
tri-chloride, potassium tri-bromide, potassium tri-iodide, and
combinations thereof.
53. The method of claim 51, wherein the one or more oxidizing agent
comprises about 5 wt. % to about 50 wt. % of a total adsorptive
material.
54. The method of claim 45, further comprising one or more nitrogen
source.
55. The method of claim 54, wherein the one or more nitrogen source
is selected from the group consisting of ammonium containing
compounds, ammonia containing compounds, amines containing
compounds, amides containing compounds, imines containing
compounds, quaternary ammonium containing compounds, and
combinations thereof.
56. The method of claim 54, wherein the one or more nitrogen source
is selected from the group consisting of ammonium iodide, ammonium
bromide, or ammonium chloride, amine halides, a quaternary ammonium
halides, and combinations thereof.
57. The method of claim 54, wherein the one or more nitrogen source
comprises about 5 wt. % to about 50 wt. % of a total adsorptive
material.
58. The method of claim 45, further comprising an alkaline
agent.
59. The method of claim 58, wherein the alkaline agent is selected
from the group consisting of alkaline agent may be calcium
carbonate, calcium oxide, calcium hydroxide, magnesium carbonate,
magnesium hydroxide, magnesium oxide, sodium carbonate, sodium
bicarbonate, trisodium hydrogendicarbonate dihydrate, and
combinations thereof.
60. The method of claim 58, wherein the alkaline agent is provided
at a concentration of greater than or equal to about 0.15
equivalents per 100 grams of absorptive material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 61/658,258, entitled, "Sorbents for Removal of
Mercury," filed Jun. 11, 2012, which is incorporated herein by
reference in its entirety.
GOVERNMENT INTERESTS
[0002] NOT APPLICABLE
PARTIES TO A JOINT RESEARCH AGREEMENT
[0003] NOT APPLICABLE
INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT
DISC
[0004] NOT APPLICABLE
BACKGROUND
[0005] Mercury is a known environmental hazard and leads to health
problems for both humans and non-human animal species.
Approximately 50 tons per year are released into the atmosphere in
the United States, and a significant fraction of the release comes
from emissions from coal burning facilities such as electric
utilities. To safeguard the health of the public and to protect the
environment, the utility industry is continuing to develop, test,
and implement systems to reduce the level of mercury emissions from
its plants. In the combustion of carbonaceous materials, it is
desirable to have a process wherein mercury and other undesirable
compounds are captured and retained after the combustion phase so
that they are not released into the atmosphere.
[0006] One of the most promising solutions for mercury removal from
flue gas is Activated Carbon Injection (ACI). Activated carbon is a
highly porous, non-toxic, readily available material that has a
high affinity for mercury vapor. This technology is already
established for use with municipal incinerators. Although the ACI
technology is effective for mercury removal, the short contact time
between the activated carbon and the flue gas stream results in an
inefficient use of the full adsorption capacity of the activated
carbon. Mercury is adsorbed while the carbon is conveyed in the
flue gas stream along with fly ash from the boiler. The carbon and
fly ash are then removed by a particulate capture device such as an
Electrostatic Precipitator (ESP) or baghouse.
SUMMARY OF THE INVENTION
[0007] Various embodiments are directed to a mercury adsorptive
material comprising an adsorptive material having a volumetric
iodine number of greater than 450 mg/cc based on the gravimetric
iodine number determined using standard test method (ASTM) D-4607
or an equivalent thereof and the apparent density determined using
(ASTM) D-2854 or an equivalent thereof. In some embodiments, the
volumetric iodine number is about 500 mg/cc to about 650 mg/cc. The
adsorptive material can be any material known in the art including,
but not limited to activated carbon, reactivated carbon, graphite,
graphene, carbon black, zeolite, silica, silica gel, clay, and
combinations thereof. In some certain embodiments, the adsorptive
material has a mean particle diameter (MPD) of about 1 .mu.m to
about 30 .mu.m. In particular embodiments, the mercury adsorptive
material may include one or more oxidizing agent, such as, but not
limited to, chlorine, bromine, iodine, ammonium bromide, ammonium
chloride, calcium hypochlorite, calcium hypobromite, calcium
hypoiodite, calcium chloride, calcium bromide, calcium iodide,
magnesium chloride, magnesium bromide, magnesium iodide, sodium
chloride, sodium bromide, sodium iodide, potassium tri-chloride,
potassium tri-bromide, potassium tri-iodide, and combinations
thereof, and the one or more oxidizing agent may be about 5 wt. %
to about 50 wt. % of a total adsorptive material. In certain
embodiments, the mercury adsorptive material may include one or
more nitrogen source such as, for example, ammonium containing
compounds, ammonia containing compounds, amines containing
compounds, amides containing compounds, imines containing
compounds, quaternary ammonium containing compounds, and
combinations thereof, and the one or more nitrogen source may be
about 5 wt. % to about 50 wt. % of a total adsorptive material. In
some embodiments, the one or more nitrogen source may be ammonium
iodide, ammonium bromide, or ammonium chloride, amine halides, a
quaternary ammonium halides, organo-halides, and combinations
thereof. In further embodiments, the mercury adsorptive material
may include an alkaline agent such as, but not limited to, calcium
carbonate, calcium oxide, calcium hydroxide, magnesium carbonate,
magnesium hydroxide, magnesium oxide, sodium carbonate, sodium
bicarbonate, trisodium hydrogendicarbonate dihydrate, and
combinations thereof, and the alkaline agent may be provided at a
concentration of greater than or equal to about 0.15 equivalents
per 100 grams of absorptive material.
[0008] Other embodiments are directed to a system for removing
mercury from flue gas including an adsorptive material having a
volumetric iodine number of greater than 450 mg/cc based on the
gravimetric iodine number determined using standard test method
(ASTM) D-4607 or an equivalent thereof and the apparent density
determined using (ASTM) D-2854 or an equivalent thereof. In some
embodiments, the volumetric iodine number is about 500 mg/cc to
about 650 mg/cc. The system can be any material known in the art
including, but not limited to activated carbon, reactivated carbon,
graphite, graphene, zeolite, silica, silica gel, clay, and
combinations thereof. In some certain embodiments, the adsorptive
material has a mean particle diameter (MPD) of about 1 .mu.m to
about 30 .mu.m. In particular embodiments, the system may include
one or more oxidizing agent, such as, but not limited to, chlorine,
bromine, iodine, ammonium bromide, ammonium chloride, calcium
hypochlorite, calcium hypobromite, calcium hypoiodite, calcium
chloride, calcium bromide, calcium iodide, magnesium chloride,
magnesium bromide, magnesium iodide, sodium chloride, sodium
bromide, sodium iodide, potassium tri-chloride, potassium
tri-bromide, potassium tri-iodide, and combinations thereof, and
the one or more oxidizing agent may be about 5 wt. % to about 50
wt. % of a total adsorptive material. In certain embodiments, the
system may include one or more nitrogen source such as, for
example, ammonium containing compounds, ammonia containing
compounds, amines containing compounds, amides containing
compounds, imines containing compounds, quaternary ammonium
containing compounds, and combinations thereof, and the one or more
nitrogen source may be about 5 wt. % to about 50 wt. % of a total
adsorptive material. In some embodiments, the one or more nitrogen
source may be ammonium iodide, ammonium bromide, or ammonium
chloride, amine halides, a quaternary ammonium halides,
organo-halides, and combinations thereof. In further embodiments,
the system may include an alkaline agent such as, but not limited
to, calcium carbonate, calcium oxide, calcium hydroxide, magnesium
carbonate, magnesium hydroxide, magnesium oxide, sodium carbonate,
sodium bicarbonate, trisodium hydrogendicarbonate dihydrate, and
combinations thereof, and the alkaline agent may be provided at a
concentration of greater than or equal to about 0.15 equivalents
per 100 grams of absorptive material.
[0009] Further embodiments are directed to a method for mercury
removal including the step of injecting an adsorptive material
having a volumetric iodine number of greater than 450 mg/cc based
on the gravimetric iodine number determined using standard test
method (ASTM) D-4607 or an equivalent thereof and the apparent
density determined using (ASTM) D-2854 or an equivalent thereof
into a flue gas stream. In some embodiments, the adsorptive
material may have a volumetric iodine number is about 500 mg/cc to
about 650 mg/cc. The adsorptive material may be, for example,
activated carbon, reactivated carbon, graphite, graphene, zeolite,
silica, silica gel, clay, and combinations thereof and may have a
mean particle diameter (MPD) of about 1 .mu.m to about 30 .mu.m.
The adsorptive material may further include any of the additives
described above.
DESCRIPTION OF DRAWINGS
[0010] In the following detailed description, reference is made to
the accompanying drawings, which form a part hereof. In the
drawings, similar symbols typically identify similar components
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 herein. It will be readily understood
that the aspects of the present disclosure, as generally described
herein and illustrated in the Figures, can be arranged,
substituted, combined, separated, and designed in a wide variety of
different configurations, all of which are explicitly contemplated
herein.
[0011] FIG. 1 is a graph showing the relationship between
gravimetric iodine number and adsorption of mercury.
[0012] FIG. 2 is a graph showing the relationship between
volumetric iodine number and adsorption of mercury for an
adsorbent.
DETAILED DESCRIPTION
[0013] Before the present compositions and methods are described,
it is to be understood that this invention is not limited to the
particular processes, compositions, or methodologies described, as
these may vary. It is also to be understood that the terminology
used in the description is for the purpose of describing the
particular versions or embodiments only, and is not intended to
limit the scope of the present invention, which will be limited
only by the appended claims. Unless defined otherwise, all
technical and scientific terms used herein have the same meaning as
commonly understood by one of ordinary skill in the art. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of embodiments of the
present invention, the preferred methods, devices, and materials
are now described. All publications mentioned herein are
incorporated by reference in their entirety. Nothing herein is to
be construed as an admission that the invention is not entitled to
antedate such disclosure by virtue of prior invention.
[0014] It must also be noted that as used herein and in the
appended claims, the singular forms "a," "an," and "the" include
plural reference unless the context clearly dictates otherwise.
Thus, for example, reference to "a combustion chamber" is a
reference to "one or more combustion chambers" and equivalents
thereof known to those skilled in the art, and so forth.
[0015] As used herein, the term "about" means plus or minus 10% of
the numerical value of the number with which it is being used.
Therefore, about 50% means in the range of 45%-55%.
[0016] Embodiments of the invention are directed to mercury
sorbents having enhanced mercury removal capabilities in flue gas
streams. Such mercury sorbents have include a mercury adsorptive
material having an iodine number of greater than 300 mg/g, and in
other embodiments, the mercury adsorptive material may have an
iodine number from about 700 mg/g to about 1500 mg/g. In still
other embodiments, these mercury sorbents may include one or more
additives that may further enhance the effectiveness of the mercury
adsorptive material.
[0017] The mercury adsorptive material of the sorbent composition
of various embodiments may include any material having an affinity
for mercury. For example, in some embodiments, the mercury
adsorptive material may be a porous sorbent having an affinity for
mercury including, but not limited to, activated carbon,
reactivated carbon, graphite, graphene, zeolite, silica, silica
gel, clay, and combinations thereof, and in particular embodiments,
the mercury adsorptive material may be activated carbon. The
mercury adsorptive material may have any mean particle diameter
(MPD). For example, in some embodiments, the MPD of the mercury
adsorptive material may be from about 0.1 .mu.m to about 100 .mu.m,
and in other embodiments, the MPD may be about 1 .mu.m to about 30
.mu.m. In still other embodiments, the MPD of the mercury
adsorptive material may be less than about 15 .mu.m, and in some
particular embodiments, the MPD may be about 2 .mu.m to about 10
.mu.m, about 4 .mu.m to about 8 .mu.m, or about 5 .mu.m or about 6
.mu.m. In certain embodiments, the mercury adsorptive materials may
have an MPD of less than about 12 .mu.m, or in some embodiments,
less than 7 .mu.m, which may provide increased selectivity for
mercury oxidation.
[0018] In certain embodiments, the mercury adsorbent may have high
activity as determined by having an iodine number of greater than
300 mg/g. Iodine number is used to characterize the performance of
adsorptive materials based on the adsorption of iodine from
solution. This provides an indication of the pore volume of the
adsorbent material. More specifically, iodine number is defined as
the milligrams of iodine adsorbed by one gram of carbon when the
iodine concentration in the residual filtrate is 0.02 normal.
Greater amounts of adsorbed iodine indicates that the activated
carbon has a higher surface area for adsorption and a higher degree
of activation activity level. Thus, a higher "iodine number"
indicates higher activity. As used herein, the term "iodine number"
can refer to either a gravimetric iodine number or a volumetric
iodine number. Gravimetric iodine number can be determined using
standard test method (ASTM) D-4607, which is hereby incorporated by
reference in its entirety, or equivalent thereof. Volumetric iodine
number is a product of the gravimetric iodine number (mg of iodine
adsorbed/gram of carbon) and the apparent density of the activated
carbon (grams of carbon/cc of carbon), which an apparent density
can be determined using ASTM D-2854, which is hereby incorporated
by reference in its entirety, or an equivalent thereof. In other
embodiments, granular or powdered carbon or any other form of
carbon where the ASTM apparent density test cannot properly be
applied, the apparent density can be determined using mercury
porosimetry test ASTM 4284-12 to determine the void volume via
mercury intrusion volume at 1 pound per square inch actual
pressure. This intrusion volume defines the void volume of the
carbon sample to allow calculation of the carbon particle density,
and the apparent density is then calculated by correcting this
particle density for the void fraction in a dense packed container
of the carbon sample. The void fraction is 40% for a typical 3 fold
range in particle size for the sample. Thus, Calculated Apparent
Density (g.Carbon/cc.Carbon container)=Particle Density
(g.carbon/cc.carbon particle volume)*(100%-40% voids)/100%. The
result is a volume based activity with the units of mg of iodine
adsorbed per cc of carbon.
[0019] Adsorbent materials typically used for mercury adsorption
have an iodine number, based on the gravimetric iodine number, of
about 300 mg/g to about 400 mg/g, which is thought to provide
equivalent performance in mercury adsorption characteristics to
adsorptive materials having higher iodine numbers. Various
embodiments of the invention are directed to mercury sorbents that
include adsorbent materials having gravimetric iodine number for
greater than 400 mg/g, greater than 500 mg/g, greater than 600
mg/g, greater than 700 mg/g, greater than 800 mg/g, greater than
900 mg/g, and so on or any gravimetric iodine number therebetween.
In other embodiments, the adsorptive material may have an iodine
number of from about 500 mg/g to about 1500 mg/g, about 700 mg/g to
about 1200 mg/g, or about 800 mg/g to about 1100 mg/g, or any
gravimetric iodine number between these exemplary ranges. In
further embodiments, mercury adsorbents exhibiting an iodine number
within these exemplary ranges may be an activated carbon or
carbonaceous char.
[0020] As determined using volumetric iodine number methods,
adsorbent materials for mercury adsorption may have a volumetric
iodine number from about 350 mg/cc to about 800 mg/cc. In
embodiments of the invention described herein, the volumetric
iodine number may be greater than 400 mg/cc, greater than 500
mg/cc, greater than 600 mg/cc, greater than 700 mg/cc, and so on or
any volumetric iodine number therebetween. In other embodiments,
the adsorptive material may have a volumetric iodine number of from
about 350 mg/cc to about 650 mg/cc, about 400 mg/cc to about 600
mg/cc, about 500 mg/cc to about 600 mg/cc, about 500 mg/cc to about
700 mg/cc, or any volumetric iodine number between these ranges. In
further embodiments, mercury adsorbents exhibiting an iodine number
within these exemplary ranges may be an activated carbon or
carbonaceous char, and in certain embodiments, these activated
carbon or carbonaceous chars exhibiting a volumetric iodine number
of 400 mg/cc or greater may be combined with activated carbons and
carbonaceous chars exhibiting a volumetric iodine number that is
less than 400 mg/cc.
[0021] Without wishing to be bound by theory, adsorbent materials
having an iodine number within these exemplary ranges may provide
improved adsorption over adsorbent materials having a gravimetric
iodine number within the commonly used range of about 300 mg/g to
about 400 mg/g. For example, in certain embodiments, about one half
as much activated carbon having a gravimetric iodine number between
about 700 mg/g to about 1200 mg/g or a volumetric iodine number of
about 500 mg/cc to about 2200 mg/cc may be necessary to adsorb the
amount of mercury adsorbed by conventional activated carbon. Thus,
certain embodiments, are directed to methods in which about 5
lbs/hr to about 10 lbs/hr of activated carbon having an iodine
number of from about 700 mg/g to about 1200 mg/g or a volumetric
iodine number of about 500 mg/cc to about 2200 mg/cc can adsorb an
equivalent amount of mercury as about 15 lbs/hr of an activated
carbon having an gravimetric iodine number of about 500 mg/g (see,
Example 1).
[0022] In still other embodiments, any of the adsorptive materials
described above may be treated with one or more oxidizing agents
that enhance mercury adsorption. For example, in some embodiments,
the oxidizing agent may be a halogen salt including inorganic
halogen salts, which for bromine may include bromides, bromates,
and hypobromites, for iodine may include iodides, iodates, and
hypoiodites, and for chlorine may be chlorides, chlorates, and
hypochlorites. In certain embodiments, the inorganic halogen salt
may be an alkali metal or an alkaline earth element containing
halogen salt where the inorganic halogen salt is associated with an
alkali metal such as lithium, sodium, and potassium or alkaline
earth metal such as magnesium, and calcium counterion. Non-limiting
examples of inorganic halogen salts including alkali metal and
alkali earth metal counterions include calcium hypochlorite,
calcium hypobromite, calcium hypoiodite, calcium chloride, calcium
bromide, calcium iodide, magnesium chloride, magnesium bromide,
magnesium iodide, sodium chloride, sodium bromide, sodium iodide,
potassium tri-chloride, potassium tri-bromide, potassium
tri-iodide, and the like. The oxidizing agents may be included in
the composition at any concentration, and in some embodiments, no
oxidizing agent may be included in the compositions embodied by the
invention. In embodiments in which oxidizing agents are included,
the amount of oxidizing agent may be from about 5 wt. % or greater,
about 10 wt. % or greater, about 15 wt. % or greater, about 20 wt.
% or greater, about 25 wt. % or greater, about 30 wt. % or greater,
about 40 wt. % or greater of the total sorbent, or about 5 wt. % to
about 50 wt. %, about 10 wt. % to about 40 wt. %, about 20 wt. % to
about 30 wt. %, or any amount therebetween.
[0023] In further embodiments, any of the adsorptive materials
described above may be treated with one or more nitrogen source.
The nitrogen source of such agents may be any nitrogen sources are
known in the art and can include, for example, ammonium, ammonia,
amines, amides, imines, quaternary ammonium, and the like. In
certain embodiments, the agent may be, for example, chlorine,
bromine, iodine, ammonium halide, such as, ammonium iodide,
ammonium bromide, or ammonium chloride, an amine halide, a
quaternary ammonium halide, or an organo-halide and combinations
thereof. In some embodiments, the nitrogen containing agent may be
ammonium halide, amine halide, or quaternary ammonium halide, and
in certain embodiments, the agent may be an ammonium halide such as
ammonium bromide. In various embodiments, the nitrogen containing
agent may be provided about 5 wt. % or greater, about 10 wt. % or
greater, about 15 wt. % or greater, about 20 wt. % or greater,
about 25 wt. % or greater, about 30 wt. % or greater, about 40 wt.
% or greater of the total sorbent, or about 5 wt. % to about 50 wt.
%, about 10 wt. % to about 40 wt. %, about 20 wt. % to about 30 wt.
%, or any amount therebetween.
[0024] The ammonium halide, amine halide, or quaternary ammonium
halide may be absent in some embodiments, in other embodiments, the
ammonium halide, amine halide, or quaternary ammonium halide may be
the only additive included in the sorbent composition, and in still
other embodiments, the ammonium halide, amine halide, or quaternary
ammonium halide may be combined with other agents such as, for
example, halide salts, halide metal salts, alkaline agents, and the
like to prepare a composition or sorbent encompassed by the
invention. In particular embodiments, sorbent may include at least
one of a halogen salt such as sodium bromide (NaBr), potassium
bromide (KBr), or ammonium bromide (NH.sub.4Br).
[0025] In some embodiments, the adsorbent material may be combined
with an acid gas suppression agent such as, for example, alkaline
agent. Numerous alkaline agents are known in the art and currently
used to remove sulfur oxide species from flue gas and any such
alkaline agent may be used in the invention. For example, in
various embodiments, the alkaline additive may be alkali oxides,
alkaline earth oxides, hydroxides, carbonates, bicarbonates,
phosphates, silicates, aluminates, and combinations thereof, and in
certain embodiments, the alkaline agent may be calcium carbonate
(CaCO.sub.3; limestone), calcium oxide (CaO; lime), calcium
hydroxide (Ca(OH).sub.2; slaked lime); magnesium carbonate
(MgCO.sub.3; dolomite), magnesium hydroxide (Mg(OH).sub.2),
magnesium oxide (MgO), sodium carbonate (Na.sub.2CO.sub.3), sodium
bicarbonate (NaHCO.sub.3), trisodium hydrogendicarbonate dihydrate
(Na.sub.3H(CO.sub.3).sub.2.2H.sub.2O; trona), and combinations
thereof. In various embodiments, the alkaline agent may be provided
at a concentration greater than or equal to about 0.15 equivalents
per 100 grams of absorptive material, wherein one equivalent of the
alkaline agent is defined as the amount required to produce one
mole of hydroxyl ions or to react with one mole of hydrogen ions.
In particular embodiments, such alkaline agents may have a
relatively high surface area such as, for example, above 100
m.sup.2/g for neat materials. High surface area materials may
provide improved kinetics and capabilities for acid gas or SO.sub.x
mitigation while complementing halogen compounds and other added
oxidants to provide oxidation of elemental mercury. Because
alkaline agents are highly polar materials that may associate and
bond with water, in various embodiments, alkaline agents may be
combined with the primary mercury sorbent as a physical admixture
and may not generally be present on the sorbent surface or
contained within the sorbent pore structure.
[0026] In other embodiments, the mercury adsorptive material may be
treated to enhance the hydrophobicity of the adsorptive materials
with, for example, one or more hydrophobicity enhancement agents
that impede the adsorption and transport of water or other
treatments of the sorbent that achieve similar results. Embodiments
are not limited to the type of treated mercury adsorptive material
or the means by which the mercury adsorptive material has been
treated with a hydrophobicity enhancement agent. For example, in
some embodiments, the mercury adsorptive material may be treated
with an amount of one or more elemental halogen that can form a
permanent bond with the surface. The elemental halogen may be any
halogen such as fluorine (F), chlorine (Cl), or bromine (Br), and
in certain embodiments, the elemental halogen may be fluorine (F).
In other embodiments, the mercury adsorptive material may be
treated with a hydrophobicity enhancement agent such as a fluorine
salt, organo-fluorine compound, or fluorinated polymer, such as,
TEFLON.RTM..
[0027] In such embodiments, treatment may be effectuated by
grinding the mercury adsorptive material with the organo-fluorine
compound or fluorinated polymer. In still other embodiments, carbon
sorbents used as the mercury adsorptive material may be treated
with mineral acids such as but not limited to, hydrochloric acid,
nitric acid, boric acid, and sulfuric acid, under high temperature,
e.g., greater than about 400.degree. C. or greater than 600.degree.
C. or greater than 800.degree. C. The concentration of the acid is
not critical to such treatments and concentrations as low as 1.0
percent by weight or less may be used. Without wishing to be bound
by theory, such treatment may enhance hydrophobicity and decreased
activity for the catalytic oxidation of sulfur dioxide to sulfuric
acid in the presence of oxygen and water. Evidence of such
treatments can be found in a high contact pH and a reduced tendency
for the carbon alone to decompose hydrogen peroxide when compared
to the same carbon without such treatments.
[0028] The adsorbent material may be combined with an oxidizing
agent, nitrogen containing compound, hydrophobicity agent, acid gas
suppression agent, or other mercury removal agent (collectively,
"additives") in any way known in the art. For example, in some
embodiments, the one or more additive may be introduced onto the
surface of the adsorbent material by impregnation in which the
adsorbent material is immersed in a liquid mixture of additives or
the liquid mixture of additives is sprayed or otherwise applied to
the adsorbent material. Such impregnation processes result in an
adsorbent material in which the additives are dispersed on the
surface of the adsorbent material.
[0029] In various other embodiments, treatment of the adsorbent
material may be combined with one or more additive as a dry
admixture in which particles of adsorbent are separated and apart
from particles of additive having substantially the same size. For
example, in some embodiments, may be provided by co-milling
activated carbon with one or more additive to a mean particle
diameter (MPD) of less than or equal to about 12 .mu.m, less than
or equal to about 10 .mu.m, or less than about 7 .mu.m. Without
wishing to be bound by theory, reducing the mean particle diameter
of the sorbent and additives by co-milling allows for a close
localization of the sorbent and the additives, but the additives
are not contained within the sorbent pore structure. These dry
admixtures have been found to be surprisingly effective in
facilitating rapid and selective mercury adsorption. This effect
has been shown particularly effective when all of components of the
sorbent are combined and co-milled or otherwise sized to a mean
particle diameter of less than or equal to about 12 .mu.m.
Co-milling may be carried out by any means. For example, in various
embodiments, the co-milling may be carried out using bowl mills,
roller mills, ball mills, jet mills or other mills or any grinding
device known to those skilled in the art for reducing the particle
size of dry solids.
[0030] Although not wishing to be bound by theory, the small MPD
may improve the selectivity of mercury adsorption as the halide
effectively oxidizes the mercury. As such, dry admixtures of
adsorbent materials and additive may allow for a higher percentage
of active halide and alkaline agents to be included in the injected
sorbent. Mercury adsorbents that are impregnated with an additive
by treating with an aqueous solution of the additive, for example,
commercial brominated carbon sorbents, especially those impregnated
with elemental bromine, can only retain a small percentage of the
additive on the surface of the adsorbent, and impregnation tends to
clog the pores of porous mercury adsorbents reducing the surface
area available for mercury adsorption. In contrast, the percentage
of additive in a dry mixture may be greater than about 10 wt. %,
greater than about 15 wt. %, greater than about 20 wt. %, or
greater than about 30 wt. % and up to about 50 wt. %, up to about
60 wt. %, or up to about 70 wt. % without exhibiting a reduction in
mercury adsorption efficiency.
[0031] While co-grinding is useful in some embodiments, adsorptive
material and additives may be combined by any method. For example,
in some embodiments, an adsorptive material and one or more
additive may be combined by blending or mixing the materials into a
single mercury sorbent that can then be injected into a flue gas
stream. In other embodiments, combining may occur during use such
that the adsorptive material and the one or more additive are held
in different reservoirs and injected simultaneously into a flue gas
stream.
[0032] Further embodiments are directed to methods for removing
mercury from flue gas by injecting a mercury adsorbent including a
mercury sorbent described above including an adsorbent material and
one or more oxidizing agent, nitrogen containing compound,
hydrophobicity agent, acid gas suppression agent, or other mercury
removal agent into a flue gas stream. The sorbents described herein
may be used to adsorb mercury in any flue gas stream. For example,
the sorbents of various embodiments may be used in flue gas streams
having no or extremely low SO.sub.3 content or flue gas streams
containing high concentrations of other acid gases such as HCl, HF,
or NO.sub.x species.
[0033] In some embodiments, the mercury adsorptive material and one
or more additive may be combined prior to injection into the flue
gas stream by, for example, mixing or blending, the mercury
adsorptive material with the one or more additives. In other
embodiments, the mercury adsorptive material and one or more
additives may be injected separately into the flue gas stream and
combined in the flue gas stream itself. In still other embodiments,
the mercury adsorbent material and the one or more additives may be
introduced into a flue gas stream in different portions of the flue
gas stream. For example, in some embodiments, all adsorbent
materials and additives may be introduced into the flue gas stream
simultaneously and at the same portion of the flue gas stream. In
other embodiments, an additive such as, for example, a halide salt
may be introduced into a boiler or a upstream portion of the flue
gas stream and the adsorbent and one or more additional additives
may be introduced into the flue gas stream either simultaneously or
separately in one or more downstream portions of the flue gas
stream.
EXAMPLES
[0034] Although the present invention has been described in
considerable detail with reference to certain preferred embodiments
thereof, other versions are possible. Therefore the spirit and
scope of the appended claims should not be limited to the
description and the preferred versions contained within this
specification. Various aspects of the present invention will be
illustrated with reference to the following non-limiting
examples.
Example 1
[0035] Activated carbons of various activity levels were
investigated for their ability to remove mercury from flue gas.
Activity was based on the gravimetric iodine number (ASTM D-4607)
and volumetric iodine number which the gravimetric iodine number
converted to a volumetric basis using the density of the granular
material (ASTM D2854). Carbons were all approximately 7 um in size
and were injected into test flue gas upstream of the electrostatic
precipitator (ESP) either alone or in a dry admixture with 30% w/w
ammonium bromide. Results are reported based on lbs/hr required to
remove 90% of the mercury in the flue gas stream.
[0036] FIGS. 1 and 2 shows performance curves for base carbons (no
additive) and the base carbon in a dry admixture of 30% w/w
ammonium bromide. FIG. 1 shows the relationship of gravimetric
iodine number (mg/g) to the amount of adsorbent required to reach
90% mercury removal, and FIG. 2 shows the relationship between
volumetric iodine number (mg/cc) and the amount of adsorbent
required to 90% mercury removal. Table 1 shows the apparent density
and gravimetric iodine number used to calculate the volumetric
iodine number.
TABLE-US-00001 TABLE 1 Apparent Gravimetric Iodine Volumetric
Iodine Density Number Number (g/cc) (mg/g) (mg/cc) 0.78 490 382
0.63 850 536 0.53 1150 610
[0037] As illustrated in FIGS. 1 and 2, 15.4 lbs/hr of carbon
having an gravimetric iodine number of 462 mg/g and a volumetric
iodine number of about 382 mg/cc is required to remove 90% of the
mercury from the flue gas stream. In contrast, about 8.3 lbs/hr is
required to remove 90% of the mercury from the flue gas stream with
activated carbon having a gravimetric iodine number of 1150 mg/g
and a volumetric iodine number of about 610 mg/cc. This provides an
about 45% reduction in the amount of activated carbon required to
remove 90% of the mercury from a flue gas stream when the activity
as determined by iodine number is increased by 40%.
[0038] FIGS. 1 and 2 also show performance curves for carbons
including 30% w/w additive (ammonium bromide) is combined with the
activated carbon in a dry admixture before being injected into the
flue gas upstream of the ESP. Initially, a 40% reduction in the
amount of activated carbon (from 15.4 lbs/hr to 6.2 lbs/hr)
necessary to remove 90% of the mercury from the flue gas stream was
observed by the addition of ammonium bromide to the activated
carbon having an gravimetric iodine number of 462 mg/g. The
adsorption of mercury is further enhanced by the introduction of
adsorbent having higher activity based on iodine number.
Specifically, 1.8 lbs/hr of activated carbon is necessary to remove
90% of the mercury from the flue gas when activated carbon having a
gravimetric iodine number of 1150 mg/g and a volumetric iodine
number of about 610 mg/cc. This represents a 60% reduction in the
amount of activated carbon necessary to reduce the amount of
mercury in a full gas stream by 90%. Additionally, the performance
curves resulting from activated carbon ammonium bromide mixtures
exhibit a non-linear relationship which could be indicative of a
synergetic interaction between ammonium bromide addition and both
volumetric and gravimetric iodine activity.
[0039] FIG. 2 also shows a non-linear decrease in the amount of
carbon required when the volumetric iodine number is above about
500 mg/cc when ammonium bromide is present as an admix.
Additionally in FIG. 2. increasing the volume iodine value of the
base carbon does not have a large effect on the performance of this
material.
* * * * *