U.S. patent application number 11/460547 was filed with the patent office on 2008-08-14 for oil shale derived pollutant control materials and methods and apparatuses for producing and utilizing the same.
This patent application is currently assigned to BATTELLE ENERGY ALLIANCE, LLC. Invention is credited to Richard D. Boardman, Robert A. Carrington.
Application Number | 20080193351 11/460547 |
Document ID | / |
Family ID | 38981783 |
Filed Date | 2008-08-14 |
United States Patent
Application |
20080193351 |
Kind Code |
A9 |
Boardman; Richard D. ; et
al. |
August 14, 2008 |
OIL SHALE DERIVED POLLUTANT CONTROL MATERIALS AND METHODS AND
APPARATUSES FOR PRODUCING AND UTILIZING THE SAME
Abstract
Pollution control substances may be formed from the combustion
of oil shale, which may produce a kerogen-based pyrolysis gas and
shale sorbent, each of which may be used to reduce, absorb, or
adsorb pollutants in pollution producing combustion processes,
pyrolysis processes, or other reaction processes. Pyrolysis gases
produced during the combustion or gasification of oil shale may
also be used as a combustion gas or may be processed or otherwise
refined to produce synthetic gases and fuels.
Inventors: |
Boardman; Richard D.; (Idaho
Falls, ID) ; Carrington; Robert A.; (Idaho Falls,
ID) |
Correspondence
Address: |
BATTELLE ENERGY ALLIANCE, LLC
P.O. BOX 1625
IDAHO FALLS
ID
83415-3899
US
|
Assignee: |
BATTELLE ENERGY ALLIANCE,
LLC
P.O. Box 1625
Idaho Falls
ID
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20060280666 A1 |
December 14, 2006 |
|
|
Family ID: |
38981783 |
Appl. No.: |
11/460547 |
Filed: |
July 27, 2006 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11004698 |
Dec 2, 2004 |
7384615 |
|
|
11460547 |
Jul 27, 2006 |
|
|
|
Current U.S.
Class: |
423/210 ;
423/445R |
Current CPC
Class: |
B01D 53/60 20130101;
Y02A 50/2344 20180101; C04B 7/4446 20130101; F23G 2900/7013
20130101; C04B 7/364 20130101; B01D 53/46 20130101; F23J 7/00
20130101; B01D 2251/20 20130101; B01D 2257/204 20130101; B01D
2257/404 20130101; B01D 2253/20 20130101; Y10S 502/514 20130101;
B01D 2257/308 20130101; B01D 2257/602 20130101; F23J 15/003
20130101; Y02A 50/20 20180101; Y02C 20/30 20130101; B01D 2257/302
20130101 |
Class at
Publication: |
423/210 ;
423/445.00R |
International
Class: |
B01D 47/00 20060101
B01D047/00 |
Goverment Interests
GOVERNMENT RIGHTS
[0002] The United States Government has rights in the following
invention pursuant to Contract No. DE-AC07-05-ID14517, between the
United States Department of Energy and Battelle Energy Alliance,
LLC.
Claims
1. A method for decreasing pollutants produced in a thermal
conversion process, comprising: producing at least one pollutant in
a thermal conversion process; introducing a plurality of shale
sorbent particles to the thermal conversion process; and contacting
the at least one pollutant with at least one of the plurality of
shale sorbent particles.
2. The method of claim 1, wherein producing at least one pollutant
comprises producing at least one pollutant selected from the group
consisting of nitrogen-containing pollutants, sulfuric acid, sulfur
trioxide, carbonyl sulfide, carbon disulfide, chlorine, hydroiodic
acid, iodine, hydrofluoric acid, fluorine, hydrobromic acid,
bromous acid, bromine, phosphoric acid, phosphorous pentaoxide,
phosphine, phosphonium compounds, elemental mercury, and mercuric
chloride.
3. The method of claim 1, wherein the thermal conversion process
comprises a thermal conversion process selected from the group
consisting of a coal boiler process, a pulverized coal combustor
process, a cement kiln process, an ore refining process, a metals
refining process, a calcination process, and a metal pyrolysis
process.
4. The method of claim 1, wherein the thermal conversion process
comprises a thermal conversion process producing heat from a device
selected from the group consisting of a furnace, a combustion
chamber, a pulverized coal combustion chamber, a fluidized bed
combustion chamber, a circulating bed combustion chamber, a staged
reactor combustion chamber, an entrained-flow combustion chamber, a
boiler, a reactor, a retort, a pyrolizer, a gasifier, a calcination
device, an ore refining process, a metals refining process, an
offgas duct, an offgas cleanup transport reactor, and a cement
kiln.
5. The method of claim 1, wherein the plurality of shale sorbent
particles comprises at least one shale sorbent particle produced by
the combustion of oil shale.
6. The method of claim 1, wherein introducing a plurality of shale
sorbent particles to the thermal conversion process further
comprises introducing at least a portion of the plurality of shale
sorbent particles to the thermal conversion process with a material
selected from the group consisting of a cement clinker producing
material, coal, pulverized coal, a fuel, a combustion product, a
combustible material, and a gas.
7. The method of claim 1, wherein introducing a plurality of shale
sorbent particles to the thermal conversion process comprises
introducing a plurality of shale sorbent particles into a product
stream of the thermal conversion process.
8. The method of claim 1, wherein contacting the at least one
pollutant with at least one of the plurality of shale sorbent
particles further comprises adsorption of the at least one
pollutant by the at least one of the plurality of shale sorbent
particles.
9. The method of claim 1, wherein contacting the at least one
pollutant with at least one of the plurality of shale sorbent
particles further comprises absorption of the at least one
pollutant by the at least one of the plurality of shale sorbent
particles.
10. The method of claim 1, further comprising: introducing a
pyrolysis gas to the thermal conversion process; and contacting the
at least one pollutant with the pyrolysis gas.
11. The method of claim 10, wherein introducing a pyrolysis gas to
the thermal conversion process comprises introducing a pyrolysis
gas produced by the combustion of oil shale to the thermal
conversion process.
12. The method of claim 1, further comprising: introducing oil
shale to the thermal conversion process; and thermally converting
the oil shale in the thermal conversion process to produce a
pyrolysis gas and shale sorbent particles.
13. A method of producing a pollutant control substance,
comprising: exposing oil shale to a thermal source; and producing a
shale sorbent from the oil shale exposed to the thermal source.
14. The method of claim 13, wherein exposing oil shale to a thermal
source comprises exposing the oil shale to at least one process
selected from the group consisting of heating the oil shale,
pyrolyzing the oil shale, devolatilizing the oil shale, calcining
the oil shale, reforming the oil shale, gasifying the oil shale,
retorting the oil shale, coking the oil shale, and combusting the
oil shale.
15. The method of claim 13, wherein exposing oil shale to a thermal
source comprises exposing the oil shale to a thermal source in an
apparatus selected from the group consisting of a cement kiln
combustion chamber, a calcining reactor, a coal combustion chamber,
a pulverized coal combustion chamber, a gas combustion chamber, a
furnace, a boiler, a fluidized bed combustion chamber, a
circulating bed combustion chamber, a staged reactor combustion
chamber, an entrained-flow combustion chamber, an offgas duct, and
an offgas cleanup transport reactor.
16. The method of claim 13, further comprising diverting at least a
portion of the shale sorbent to at least one process selected from
the group consisting of a storage process, a gas/oil combustion
process, a cement kiln combustion process, a calcination process,
an ore refining process, a metals refining process, a coal
combustion process, a Fischer-Tropsch process, and a fuel
refinement process.
17. The method of claim 13, further comprising contacting at least
a portion of the shale sorbent with a pollutant.
18. The method of claim 13, further comprising producing a
pyrolysis gas from the oil shale exposed to the thermal source.
19. The method of claim 18, further comprising diverting at least a
portion of the pyrolysis gas to at least one process selected from
the group consisting of a storage process, a gas/oil combustion
process, a cement kiln combustion process, a coal combustion
process, a calcination process, an ore refining process, a metals
refining process, a Fischer-Tropsch process, and a fuel refinement
process.
20. The method of claim 18, further comprising contacting at least
a portion of the pyrolysis gas with a pollutant.
21. The method of claim 20, wherein contacting at least a portion
of the pyrolysis gas with a pollutant comprises contacting at least
a portion of the pyrolysis gas with a pollutant at a temperature
between about 450.degree. C. and about 1150.degree. C.
22. A combustion apparatus, comprising: a thermal conversion zone
configured to combust a combustible material and produce at least
one pollutant selected from the group consisting of
nitrogen-containing pollutants, sulfuric acid, sulfur trioxide,
carbonyl sulfide, carbon disulfide, chlorine, hydroiodic acid,
iodine, hydrofluoric acid, fluorine, hydrobromic acid, bromous
acid, bromine, phosphoric acid, phosphorous pentaoxide, phosphine,
phosphonium compounds, elemental mercury, and mercuric chloride; at
least one pollution control material feed zone configured to accept
a pollutant control material; and a pollutant contact zone
configured to facilitate contact between a pollutant control
material introduced to the at least one pollution control material
feed zone and the at least one pollutant produced in the thermal
conversion zone.
23. The combustion apparatus of claim 22, wherein the at least one
pollution control material feed zone is configured to introduce the
pollutant control material into the thermal conversion zone.
24. The combustion apparatus of claim 22, wherein the pollutant
control material comprises a pollutant control material selected
from the group consisting of a shale sorbent produced by the
combustion of oil shale, and a pyrolysis gas produced by the
combustion of oil shale.
25. The combustion apparatus of claim 22 wherein the pollutant
control material comprises a pollutant control material produced by
the combustion of oil shale in an apparatus selected from the group
consisting of a cement kiln combustion chamber, a calcining
reactor, a coal combustion chamber, a pulverized coal combustion
chamber, a gas combustion chamber, a furnace, a boiler, a fluidized
bed combustion chamber, a circulating bed combustion chamber, a
staged reactor combustion chamber, an entrained-flow combustion
chamber, an offgas duct, and an offgas cleanup transport
reactor.
26. The combustion apparatus of claim 22, wherein the thermal
conversion zone is operated at a temperature of between about
450.degree. C. and about 1150.degree. C.
27. The combustion apparatus of claim 22, wherein the combustion
apparatus comprises at least one component selected from the group
consisting of a cement kiln combustion chamber, a calcination
reactor, a coal combustion chamber, a pulverized coal combustion
chamber, a gas combustion chamber, a furnace, a boiler, a gasifier,
a fluidized bed combustion chamber, a circulating bed combustion
chamber, a staged reactor combustion chamber, an entrained-flow
combustion chamber, a fixed-bed reactor, a fluidized-bed reactor, a
transport-bed reactor, a steam reformer reactor, a rotary-bed
reactor, an offgas duct, and an offgas cleanup transport reactor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 11/004,698, entitled "METHOD AND APPARATUS FOR
OIL SHALE POLLUTANT SORPTION/NO.sub.x REBURNING MULTI-POLLUTANT
CONTROL," which was filed on Dec. 2, 2004, and which is
incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The invention relates to the production of pollutant
sorbents, the reduction of pollutants, and energy providing fuels.
Generally, the invention relates to the use of oil shale and oil
shale products as sorbents or reductants for reducing pollutants,
and, in particular, to the thermal processing of oil shale to
produce pollutant absorbing and adsorbing solids and combustible or
reducing gases.
[0005] 2. State of the Art
[0006] Coal, oil, natural gas, oil shale, oil sands, and other
carbon-containing fuel feedstock materials (for example: forestry
industry products, byproducts, and residues; agriculture crops,
byproducts, and residues; animal wastes and carcasses; municipal
solid waste, sewage sludge solids, construction and demolition
debris, waste tires, and other forms of refuse-derived fuel) can be
converted from chemical potential energy to heat and gaseous
products that can be used to generate electrical power, or to
produce higher value chemicals and components.
[0007] In the context of this document, the term "thermal
conversion" generally implies any gaseous or solid process that
liberates or transforms the chemical potential energy into heat,
hot gases, combustible gases, combustible liquids, combustible
solids such as char, and/or non-combustible solids such as ash or
calcined minerals, or any subset of these.
[0008] Thermal conversion of such gaseous and solid materials
produces various pollutants, such as nitrogen compounds or sulfur
compounds, which are believed to be involved in the formation of
smog and acid rain. If the fuel includes mercury, the combustion
also produces mercury compounds, which have been identified by the
Environmental Protection Agency ("EPA") as a significant toxic
pollutant. Air pollutant control legislation, such as the Clean Air
Act ("CAA"), the Clean Air Interstate Regulation ("CAIR"), and the
Clean Air Mercury Regulation ("CAMR"), regulate emissions of many
of the pollutants released from thermal conversion processes.
[0009] The composition of the pollutant species produced by thermal
conversion processes is a strong function of the availability of
oxygen in the process. Under the reducing conditions of pyrolysis
and gasification, sulfur bound in the fuel is typically converted
to reduced forms of sulfur, such as hydrogen sulfide, carbonyl
sulfide, and carbon disulfide. Nitrogen contained in the fuel is
converted to reduced nitrogen compounds, including ammonia,
hydrogen cyanide, and molecular nitrogen. Most of the mercury in a
fuel is converted to volatile elemental mercury ("Hg.degree.") and
speciated mercury, such as mercury chloride ("HgCl.sub.2"). Under
reducing conditions, phosphorus ("P") reacts with metals to form
phosphate compounds, and may also be converted to phosphine
("PH.sub.3"), phosphonium compounds, and other reduced forms of
phosphorus. Chlorine ("Cl") may react with alkali metals (such as
sodium and potassium), alkali-earth metals (such as calcium and
magnesium), and other metals (such as mercury, zinc, and iron), but
it is also converted to diatomic chlorine gas ("Cl.sub.2") and
hydrochloric acid gas ("HCl"). Fluorine, bromine, and iodine behave
similar to chlorine.
[0010] Under the oxidizing conditions of combustion, sulfur bound
in the fuel is converted to gaseous sulfur dioxide or sulfur
trioxide. These sulfur compounds quickly equilibrate with moisture
("H.sub.2O") to form sulfuric acid ("H.sub.2SO.sub.4"). Nitrogen
bound in the fuel is converted to nitric oxide and nitrogen dioxide
or other oxides of nitrogen. Combustion with air also results in
nitrogen oxides as a result of high temperature reactions of atomic
oxygen ("O") and hydroxide radicals with molecular nitrogen.
Phosphorus, chlorine, fluorine, bromine, and iodine are readily
converted to phosphoric acid ("H.sub.3PO.sub.4"), hydrochloric acid
("HCl"), and hydrofluoric acid ("HF"), bromous acid ("HBrO"), and
iodic acid ("HIO.sub.3"), as well as other reactive volatile
compounds. These acid gases are corrosive to equipment used in
combustion processes, such as in a combustion device or in boiler
tubes in a combustor. Therefore, it is desirable to limit the
formation of the acid gases or to remove the acid gases close to
their point of generation in a combustion device or thermal
conversion process.
[0011] Various technologies have been developed to decrease
emissions from coal-fired powerplants. Limestone has been used as a
sorbent for SO.sub.x pollutants, as disclosed in U.S. Pat. No.
3,995,006 to Downs et al., U.S. Pat. No. 5,176,088 to Amrhein et
al. ("Amrhein"), and U.S. Pat. No. 6,143,263 to Johnson et al. This
technology is known as limestone injection multiple burner ("LIMB")
technology or limestone injection dry scrubbing ("LIDS")
technology. The limestone is injected into a region of a furnace
having a temperature of 2,000.degree. F. to 2,400.degree. F.
[0012] Limestone (mainly CaCO.sub.3) and dolomite
("CaCO.sub.3--MgCO.sub.3") and their derivatives have also been
shown to react with H.sub.2S. Either uncalcined limestone or
dolomite, half-calcined dolomite, fully calcined limestone or
dolomite, lime, or hydrated lime ("CaOH") will react to form
calcium sulfide ("CaS") or magnesium sulfide ("MgS").
[0013] Organic and amine reducing agents, such as ammonia or urea,
are used to selectively reduce NO.sub.x pollutants, as disclosed in
U.S. Pat. No. 3,900,554 to Lyon. This technique is known as
selective noncatalytic reduction ("SNCR"). The reducing agent is
injected into a furnace at a temperature from about 975K to about
1375K so that a noncatalytic reaction selectively reduces the
NO.sub.x to molecular nitrogen ("N.sub.2"). The ammonia is injected
into a region of the furnace having a temperature of 1,600.degree.
F.-2,000.degree. F.
[0014] The LIMB and SCNR technologies have been combined to
simultaneously remove the NO.sub.x pollutants and the SO.sub.x
pollutants. The limestone is used to absorb the SO.sub.x pollutants
while the ammonia is used to reduce the NO.sub.x pollutants.
However, this combination technology is expensive to implement and
adds increased complexity to the process.
[0015] NO.sub.x reburning has also been used to remove the NO.sub.x
pollutants, as disclosed in U.S. Pat. No. 5,139,755 to Seeker et
al. In NO.sub.x reburning, the coal is combusted in two stages. In
the first stage, a portion of the coal is combusted with a normal
amount of air (about 10% excess), producing the NO.sub.x
pollutants. In the second stage, the remaining portion of the coal
is combusted in a fuel-rich environment. Hydrocarbon radicals
formed by combustion of the coal react with the NO.sub.x pollutants
to form N.sub.2. Fuel/air staging has also been used to reduce the
NO.sub.x pollutants. Fuel and air are alternately injected into a
combustor to provide a reducing zone where the nitrogen in the fuel
is evolved, which promotes the conversion of the nitrogen to
N.sub.2. The air is injected at a separate location to combust the
fuel volatiles and char particles. By staging or alternating the
fuel and the air, the local temperature and the mixture of air and
fuel are controlled to suppress the formation of the NO.sub.x
pollutants. Fuel/air staging attempts to prevent NO.sub.x formation
while NO.sub.x reburning promotes NO.sub.x reduction and
destruction.
[0016] To absorb mercury or mercury-containing pollutants,
activated carbon is used as a sorbent, as disclosed in U.S. Pat.
No. 5,827,352 to Altman et al. and U.S. Pat. No. 6,712,878 to Chang
et al. The activated carbon is present as a fixed or fluidized bed
or is injected into the flue gas.
[0017] Oil shale is a sedimentary rock that includes an inorganic
matrix of carbonate, oxide, and silicate compounds impregnated with
a polymeric material called kerogen. Kerogen is an organic
substance that is insoluble in petroleum solvents. When heated, the
kerogen pyrolyzes to produce gas, oil, bitumen, and an organic
residue. Pyrolyzing the kerogen is also known as retorting. Oil
shale also includes carbonate minerals, such as calcium carbonate,
and other hydrocarbon materials, such as paraffins, cycloparaffins,
aliphatic and aromatic olefins, single ring aromatics, aromatic
furans, aromatic thiophenes, hydroxyl-aromatics, dihydroxy
aromatics, aromatic pyrroles, and aromatic pyridines, and other
poly-nuclear aromatic hydrocarbons. Oil shale is typically
co-located with coal and oil and is found in various regions of the
western United States, such as in Utah, Colorado, and Wyoming, and
in the eastern United States, such as in Virginia and Pennsylvania.
Large deposits of oil shale are also found in Canada, Australia,
Europe, Russia, China, Venezuela, and Morocco. Given the abundance
of oil shale throughout the world, its value would be significant
if beneficial uses are identified and employed. Oil shale
utilization has not been presently appreciated due to the high cost
of recovering the kerogen from the shale.
[0018] When oil shale containing considerable amounts of calcium
carbonate is heated, the calcium carbonate undergoes calcination,
which is an endothermic reaction in which the calcium carbonate
("CaCO.sub.3") is converted to lime ("CaO"). For each kilogram of
calcium carbonate that is calcined, as much as 1.4 MJ to 1.6 MJ (or
about 600 British Thermal Units ("BTU") to 700 BTU per pound mass)
of the available heat energy is consumed. This loss of energy
translates to a process efficiency penalty when limestone or
dolomite is used as an injected sorbent. In the case of oil shale,
the kerogen can be oxidized to offset the heat sink associated with
carbonate calcination.
[0019] To extract energy from the oil shale, the oil shale can be
heated in a retorting zone of a fluidized bed reactor vessel to a
temperature sufficient to release, but not combust, volatile
hydrocarbons from the oil shale, as disclosed in U.S. Pat. No.
4,373,454 to Pitrolo et al. The temperature used in the retorting
zone provides minimal calcination of the calcium carbonate. The
volatile hydrocarbons flow to a combustion zone of the fluidized
bed combustor, where the volatile hydrocarbons are combined with
excess air and are combusted. Calcination of the calcium carbonate
occurs in the combustion zone. During retorting, nitrogen compounds
in the oil shale are converted to NO.sub.x compounds and are
reduced to nitrogen and water or oxygen by the volatile
hydrocarbons.
[0020] Oil shale has been used to absorb SO.sub.2 and HCl in a
circulating fluidized bed, as disclosed in "Combustion of Municipal
Solid Wastes with Oil Shale in a Circulating Fluidized Bed,"
Department of Energy Grant No. DE-FG01-94CE15612, Jun. 6, 1996,
Energy-Related Inventions Program Recommendation Number 612,
Inventor R. L. Clayson, NIST Evaluator H. Robb, Consultant J. E.
Sinor and in "Niche Market Assessment for a Small-Scale Western Oil
Shale Project," J. E. Sinor, Report No. DOE/MC/11076-2759.
[0021] Many of the pulverized coal combustors in operation do not
meet the new standards promulgated by the United States
Environmental Protection Agency under CAIR and CAMR. Upwards of
about 75 percent of all currently existing pulverized coal
combustors may have to be phased out or retrofit to satisfy the new
pollutant standards.
BRIEF SUMMARY OF THE INVENTION
[0022] The present invention relates to a method of decreasing
pollutants produced in a pyrolysis, combustion, gasification,
stream reforming, retorting, calcination, metal refining, ore
smelting, cement production, or any other thermal conversion
process, which processes are collectively referred to herein as a
"thermal conversion" processes. The term "thermal conversion"
encompasses equivalent derivate nouns, adjectives, and verb
conjugations of this term, such as "combusting" or "combusted";
"gasifying" or "gasified"; "reforming" or "reformed"; "retorting"
or "retorted"; "calcining" or "calcined"; and "pyrolyzing" or
"pyrolyzed." The method comprises thermally converting coal or any
other carbon-containing fuel in a thermal conversion chamber to
produce at least one pollutant selected from the group consisting
of a nitrogen-containing pollutant, sulfuric acid, sulfur trioxide,
carbonyl sulfide, carbon disulfide, chlorine, hydroiodic acid,
iodic acid iodine, hydrofluoric acid, fluorine, hydrobromic acid,
bromous acid, bromine, phosphoric acid, phosphorous pentaoxide,
phosphine, phosphonium compounds, elemental mercury, and mercuric
chloride.
[0023] According to some embodiments, oil shale particles are
introduced into the thermal conversion chamber and are thermally
converted to produce sorbent particulates and a reductant or
reactive gas. The shale sorbent particulates and the reductant may
generally be produced by thermally converting the oil shale
particles at a temperature necessary to pyrolyze, retort, or
devolatilize kerogen, for example, at a temperature of greater than
or equal to approximately 200.degree. C.
[0024] In some embodiments, the oil shale particles may be
introduced into a thermal conversion process used to react with any
carbonaceous fuel, including oil shale itself. Such processes shall
be referred to as "in-situ" oil shale conversion processes.
[0025] In other embodiments, the oil shale particles may be
introduced into a separate, independent, or auxiliary thermal
conversion process used to convert the oil shale particles into
shale sorbent particles and reactive gas. These sorbent particles
and reactive gases may be routed, conveyed, or transported
separately or in combination to a coupled carbon-containing fuel
thermal conversion process. Such processes may generally be
referred to as "ex-situ" oil shale conversion processes. The shale
sorbent particles may act as a pollutant sorbent or as a pollutant
reductant.
[0026] The oil shale particles may be thermally converted to shale
sorbent particles and reducing or reactive gas in a close-coupled
reactor using the heat or the hot gases produced by a primary
carbonaceous fuel thermal conversion process. Such processes can
generally be referred to as a "close-coupled" oil shale conversion
processes.
[0027] The oil shale particles may be introduced into at least one
of a burner or combustion zone, a gasification zone, a superheater
zone, a reheat zone, or an economizer zone of any
tangentially-fired, wall-fired, or cyclonic pulverized-coal
combustion chamber. The at least one pollutant is contacted with at
least one of the sorbent particulates and the reductant to decrease
an amount of the at least one pollutant in the combustion chamber.
The reductant may chemically reduce the at least one pollutant,
such as by reducing the nitrogen-containing pollutant to molecular
nitrogen, water, and carbon dioxide. The sorbent particulates may
be used to adsorb or absorb the at least one pollutant, such as
adsorbing or absorbing at least one of sulfuric acid, sulfur
trioxide, carbonyl sulfide, carbon disulfide, chlorine, hydroiodic
acid, iodic acid, iodine, hydrofluoric acid, fluorine, hydrobromic
acid, bromous acid, bromine, phosphoric acid, phosphorous
pentaoxide, phosphine, phosphonium compounds, elemental mercury,
and mercuric chloride.
[0028] The present invention also relates to a combustion chamber
for producing decreased pollutants in a combustion process. The
combustion chamber may also comprise a burner zone that is
configured to combust coal and to produce at least one pollutant
selected from the group consisting of a nitrogen-containing
pollutant, sulfuric acid, sulfur trioxide, carbonyl sulfide, carbon
disulfide, chlorine, hydroiodic acid, iodic acid, iodine,
hydrofluoric acid, fluorine, hydrobromic acid, bromous acid,
bromine, phosphoric acid, phosphorous pentaoxide, phosphine,
phosphonium compounds, elemental mercury, and mercuric chloride.
The burner zone is also configured to thermally convert oil shale
particles to produce sorbent particulates and a reductant, which
are contacted with the at least one pollutant. The burner zone may
be configured to contact the nitrogen-containing pollutant with the
reductant to reduce the nitrogen-containing pollutant to molecular
nitrogen, carbon dioxide, and water.
[0029] The combustion chamber also comprises at least one of a
combustion zone, gasification zone, superheater zone and a reheat
zone that are each configured to thermally convert the oil shale
particles to produce the sorbent particulates and the reductant.
The superheater zone and the reheat zone are also each configured
to contact the sorbent particulates and the reductant with the at
least one pollutant. The combustion chamber also comprises at least
one of an economizer zone, an air preheat zone, and a gas cleaning
unit, which are each configured to contact the sorbent particulates
and the reductant with the at least one pollutant. Each of the
superheater zone, the reheat zone, the economizer zone, the air
preheat zone, and the gas cleaning zone is configured to contact at
least one of sulfuric acid, sulfur trioxide, carbonyl sulfide,
carbon disulfide, chlorine, hydroiodic acid, iodic acid, iodine,
hydrofluoric acid, fluorine, hydrobromic acid, bromous acid,
bromine, phosphoric acid, phosphorous pentaoxide, phosphine,
phosphonium compounds, elemental mercury, and mercuric chloride
with the sorbent particulates to adsorb or absorb at least one of
these pollutants.
[0030] In one embodiment, the combustion chamber is configured as a
pulverized coal combustor.
[0031] In other embodiments of the invention, oil shale may be
introduced into a pryolyzer, a gasifier, a combustion reactor, a
retorting reactor, a metal refining process, ore smelting process,
cement kiln, or any other thermal converter to liberate kerogen
from the oil shale, which produces a kerogen-based pyrolysis gas
and shale sorbent particles.
[0032] In other embodiments of the invention, oil shale may be
introduced into a packed bed that is contacted either directly or
indirectly with the hot gases produced by a pryolyzer, a gasifier,
a combustor, a retort, or any other thermal converter to liberate
kerogen from the oil shale, which produces a kerogen-based
pyrolysis gas and shale sorbent particles.
[0033] The pyrolysis gas produced according to embodiments of the
invention may be used as a reductant gas for reducing pollutants
such as nitrogen-containing pollutants in various processes. The
pyrolysis gas may also be used as a combustion gas or heating gas
which may be fed to a combustion process or to various combustion
zones of a combustor. In other embodiments, the pyrolysis gas may
be processed, refined, or otherwise altered to produce synthetic
gas and fuel products such as syngas and synfuels.
[0034] The shale sorbents produced according to embodiments of the
invention may be used to reduce pollutants produced in a process
such as a coal combustion process, a gasification process, a
pyrolysis process, a metal refining or smelting process, a cement
production process, or other thermal conversion process where
nitrogen-containing pollutants, sulfur-containing pollutants,
mercury-containing pollutants, or other pollutants are produced.
Introduction of the shale sorbent produced according to embodiments
of the invention into a process may result in the contact of the
shale sorbent with a pollutant such that the shale sorbent absorbs
or adsorbs the pollutant, thereby reducing the amount of pollutants
in the process.
[0035] According to still other embodiments of the invention, the
shale sorbent may be used to form cement clinker or other additives
used to enhance cement production.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0036] While the specification concludes with claims particularly
pointing out and distinctly claiming that which is regarded as the
present invention, the advantages of this invention may be more
readily ascertained from the following description of the invention
when read in conjunction with the accompanying drawing in
which:
[0037] FIG. 1 is a schematic illustration of an embodiment of a
pulverized coal combustor in which in-situ conversion of oil shale
is used to decrease pollutant levels;
[0038] FIG. 2 illustrates a simplified flow diagram of a thermal
converter for producing pyrolysis gases and shale sorbents
according to embodiments of the invention;
[0039] FIG. 3 is a schematic illustration of a coal boiler system
and a thermal converter used to produce ex-situ reducing gas and
oil shale solid sorbent according to embodiments of the
invention;
[0040] FIG. 4 is a schematic illustration of a cement kiln process
and a gasifier according to embodiments of the invention; and
[0041] FIG. 5 is a schematic illustration of a gasifier and a
syngas and/or synfuels production process according to embodiments
of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0042] Oil shale has been used to decrease or eliminate one or more
pollutants produced during combustion of a primary fuel, such as
coal, biomass, municipal solid waste ("MSW"), refuse derived fuel
("RDF"), mixtures thereof, or other fuel feed stocks. For example,
U.S. patent application Ser. No. 11/004,698, which is incorporated
herein in its entirety by reference, describes processes wherein
oil shale may be added to a combustion chamber burning a primary
fuel to reduce the amount of pollutants within the combustion
chamber and the combustion process. During combustion of a primary
fuel, the oil shale may function as a sorbent to decrease an amount
of the pollutant(s) released from the combustion chamber.
Alternatively, combustion of the oil shale may produce a reductant,
which reduces the pollutant(s) to a more benign chemical species,
decreasing the amount of the pollutant(s) released. By adjusting or
controlling a temperature or the gas composition in the combustion
chamber, the pollutant(s) may be adsorbed or absorbed onto the oil
shale or may be reduced by the reductant produced by the oil shale.
The pollutant(s) may be removed from the combustion chamber by
contacting the pollutant with the oil shale for a sufficient amount
of time for the oil shale to function as a sorbent or for the
reductant to chemically reduce the pollutant(s). The amount of time
sufficient to remove the pollutant(s) is referred to herein as a
residence time or a contact time. Pollutants that may be decreased
or eliminated by the addition of oil shale to a thermal conversion
process chamber may include, but are not limited to,
nitrogen-containing pollutants, sulfur-containing pollutants, acid
gases, and metals. Nitrogen-containing pollutants may include, for
example, NO, NO.sub.2, N.sub.2O, N.sub.2O.sub.5, or mixtures
thereof. Sulfur-containing pollutants may include, for example,
SO.sub.2, SO.sub.3, H.sub.2SO.sub.4, H.sub.2S, COS, CS.sub.2, or
mixtures thereof. In some instances, SO.sub.2 may be a major
sulfur-containing pollutant and SO.sub.3 a minor sulfur-containing
pollutant produced during combustion of primary fuels that contain
sulfur. In other instances, H.sub.2S and COS may be major
sulfur-containing pollutants produced during pyrolysis,
gasification, or thermal conversion of sulfur-containing primary
fuels. Acid gases may include, but are not limited to,
halide-containing volatile gases, such as HCl, chlorine
("Cl.sub.2"), hydroiodic acid ("HI"), iodic acid (HIO.sub.3")
iodine ("I.sub.2"), hydrofluoric acid ("HF"), fluorine ("F"),
hydrobromic ("HBr"), bromous acid ("HBrO"), bromine ("Br"), or
mixtures thereof.
[0043] Acid gases may also include phosphate-containing gases, such
as phosphoric acid ("H.sub.3PO.sub.4"), phosphorus pentaoxide
("P.sub.2O.sub.5"), phosphine ("PH.sub.3"), any phosphonium
compounds, or mixtures thereof. Metal pollutants may include one or
more elemental metals or one or more metal compounds including, but
not limited to, elemental mercury ("Hg.degree."), mercuric chloride
("HgCl.sub.2"), mercury adsorbed on particulate matter, lead ("Pb")
or compounds thereof, arsenic ("As") or compounds thereof, chromium
("Cr") or compounds thereof, or mixtures thereof. The oil shale may
be used to remove a single pollutant or multiple pollutants from
the combustion chamber. In one embodiment, the oil shale is used to
remove nitrogen-containing pollutants, H.sub.2SO.sub.4, SO.sub.3,
SO.sub.2, H.sub.2S, COS, CS.sub.2, elemental mercury, and mercuric
chloride from the combustion chamber.
[0044] Pollution control processes used with combustion chambers
have included processes where oil shale is fed directly to a
combustion chamber and, more particularly, directly to a burner
portion of a combustion chamber. In such processes, when the oil
shale is heated in the combustion chamber, shale minerals, char
particles, and kerogen are produced, as shown in Reaction 1: oil
shale+heat.fwdarw.shale minerals+char particles+kerogen+hydrocarbon
derivatives (1).
[0045] A temperature of greater than or equal to approximately
200.degree. C. may be used to pyrolyze or retort the oil shale. As
the oil shale is heated, the heat may cause the kerogen to
depolymerize and devolatilize while the shale minerals may be
calcined. The extent of depolymerization, devolatilization,
pyrolysis, and char formation of the oil shale may vary depending
on particle heat up rates, particle temperature, surrounding gas
temperature, surrounding gas temperature, and an amount of time
that the oil shale is heated. When the kerogen is devolatilized or
released from the oil shale, a porous matrix of oxides, carbonates,
or silicates may remain including, but not limited to, oxides,
carbonates, or silicates of calcium ("Ca"), magnesium ("Mg"),
sodium ("Na"), potassium ("K"), iron ("Fe"), or zinc ("Zn"). These
oxides, carbonates, and silicates are collectively referred to
herein as the shale minerals. For the sake of example only, the
shale minerals may include, but are not limited to, calcium oxide,
magnesium oxide, iron oxide, calcium carbonate, or mixtures
thereof. The char particles or particles of residual carbon may
also remain after the kerogen is devolatilized from the oil shale.
The shale minerals and char particles are collectively referred to
herein as sorbent particulates or shale sorbent particles. The
sorbent particulates are porous particles that have an increased
surface area. As such, the sorbent particulates have an increased
adsorption or absorption capability relative to that of the oil
shale and may be used to adsorb or absorb mercury and other
pollutants, as explained in detail below. Since the sorbent
particulates are porous, the pollutants may readily diffuse into
the sorbent particulates and react with the oxides, carbonates, and
silicates therein.
[0046] When oil shale is introduced into a thermal conversion
chamber, kerogen in the oil shale is released. The kerogen released
from the oil shale may provide a source of the reductant used to
reduce the nitrogen-containing pollutants in the thermal conversion
chamber. As shown in Reaction 2, the kerogen may be exposed to
additional heat to crack or scission the kerogen, forming light and
heavy hydrocarbons: kerogen+heat+radicals.fwdarw.heavy and light
hydrocarbons (C.sub.xH.sub.y)+CO+H.sub.2+CO.sub.2 (2), where x and
y depend on the carbon and hydrogen ratio in the kerogen and
temporal conditions. For instance, x may range from 1 to 7 for a
light hydrocarbon, from approximately 8 to 13 for an intermediate
hydrocarbon, or from approximately 14 to 42 for a heavy
hydrocarbon. In correlation, y may range from 1 to 90 and is
typically equal to nominally two times "x" for a given hydrocarbon.
A temperature of greater than or equal to approximately 350.degree.
C. may be used to crack and scission the polymeric kerogen. The
heavy hydrocarbons are thus progressively converted to lighter
hydrocarbons. The presence of steam helps crack and reform the
heavy hydrocarbons. The heavy and light hydrocarbons may be used to
reduce the nitrogen-containing pollutants to N.sub.2, carbon
dioxide ("CO.sub.2"), and water ("H.sub.2O") by heating the heavy
and light hydrocarbons to a temperature of greater than or equal to
approximately 400.degree. C. according to the chemistries shown in
Reactions 3 and 4:
C.sub.xH.sub.y+(2x+y/2)NO.fwdarw.(x+y/4)N.sub.2+xCO.sub.2+y/2H.sub.2O
(3),
C.sub.xH.sub.y+(x+y/4)NO.sub.2.fwdarw.(x/2+y/8)N.sub.2+xCO.sub.2+y/-
2H.sub.2O (4), where x is typically 1 or 2 and y is typically 1, 2,
3, or 4. Generally, Reactions 3 and 4 show the reduction of
oxidized compounds of nitrogen to a reduced nitrogen compound, such
as N.sub.2. Oil shale char will also reduce nitrogen-containing
pollutants to N.sub.2, CO.sub.2, and H.sub.2O by heterogeneous
reactions according or similar to the chemistries shown in
Reactions 5 and 6:
Char+(2+x)NO.fwdarw.1/2(2+x)N.sub.2+yCO.sub.2+zH.sub.2O (5),
Char+(2+x)NO.sub.2.fwdarw.1/2(2+x)N.sub.2+yCO.sub.2+zH.sub.2O (6).
Where x, y, and z are dependent on the carbon to hydrogen ratio in
the char.
[0047] The shale minerals or char particles resulting from the
combustion of the oil shale may also have an affinity for chemical
bonding with mercury or mercury compounds (adsorption) and for
physical bonding with mercury or mercury compounds (absorption).
Therefore, the shale minerals or char particles produced by the
pyrolysis of the oil shale (see Reaction 1) may adsorb or absorb
mercury or mercuric chloride according to the chemistries shown in
Reactions 7, 8, 9, and 10: char particles+Hg.degree..fwdarw.char
particles-Hg.degree. (7), char particles+HgCl.sub.2.fwdarw.char
particles-HgCl.sub.2 (8), shale
minerals+Hg.degree..fwdarw.M-Hg.degree. (9), shale
minerals+HgCl.sub.2.fwdarw.M-HgCl.sub.2 (10), where M is a metal or
metal compound present in the oil shale that has affinity for
mercury or mercuric chloride. M may include, but is not limited to,
any one of Fe, Zn, lead ("Pb"), silver ("Ag"), aluminum ("Al"),
cadmium ("Cd"), chromium ("Cr"), nickel ("Ni"), titanium ("Ti"),
selenium ("Se"), arsenic ("As"), or sulfur, including sulfur that
has been captured by the particle. When the shale minerals or char
particles come into contact with these pollutants for a sufficient
residence time, the sorbent particulates may capture the elemental
mercury or mercuric chloride. The adsorption or absorption of the
elemental mercury or mercuric chloride by the shale minerals or
char particles may also depend on a temperature at which the shale
minerals or char particles contact the elemental mercury or
mercuric chloride. The temperature may be maintained so that is it
favorable for chemical or physical adsorption, so as not to
dissociate. For example, at a temperature of less than or equal to
approximately 200.degree. C. in some embodiments. This temperature
may be achieved in a number of locations in the combustion chamber,
such as in a process duct, in a particle cake collected by a gas
cleaning unit, such as a baghouse or electrostatic precipitator
("ESP"), or in a packed-bed/gas reactor.
[0048] Other volatile and semi-volatile metals that may be removed
by the shale sorbent char and inorganic ash produced by the thermal
conversion process, include lead, arsenic, beryllium, and other
metals liberated from the carbon-containing fuel materials by the
thermal conversion process.
[0049] Carbonate or oxide compounds produced by the combustion of
the oil shale may also be used to remove sulfur-containing
pollutants, such as H.sub.2SO.sub.4, SO.sub.3, SO.sub.2, H.sub.2S,
COS, CS.sub.2, or mixtures thereof, according to the chemistries
shown in Reactions 11-19:
M.sub.x-(CO.sub.3).sub.y+heat.fwdarw.M.sub.x-O.sub.y+yCO.sub.2
(11), CaCO.sub.3+SO.sub.2+1/2O.sub.2.fwdarw.CaSO.sub.4+CO.sub.2
(12), CaCO.sub.3+SO.sub.3.fwdarw.CaSO.sub.4+CO.sub.2 (13),
CaCO.sub.3+H.sub.2SO.sub.4.fwdarw.CaSO.sub.4+CO.sub.2+H.sub.2O (14)
CaCO.sub.3+H.sub.2S.fwdarw.CaS+H.sub.2O+CO.sub.2 (15),
CaO+SO.sub.2+1/2O.sub.2.fwdarw.CaSO.sub.4 (16),
CaO+SO.sub.3.fwdarw.CaSO.sub.4 (17),
CaO+H.sub.2SO.sub.4.fwdarw.CaSO.sub.4+H.sub.2O (18)
CaO+H.sub.2S.fwdarw.CaS+H.sub.2O (19), where M is a metal, such as
Ca, Mg, Na, K, Fe, or Zn, and where x and y vary depending on the
metal carbonates present in the oil shale. For instance, x may be 1
or 2 and y may be 1, 2, or 3. While the reactions shown above are
between SO.sub.2, SO.sub.3, H.sub.2SO.sub.4, or H.sub.2S and
calcium carbonate or calcium oxide, similar reactions may occur
between SO.sub.2, SO.sub.3, or H.sub.2S and carbonates or oxides of
Mg, Na, K, Fe, or Zn.
[0050] When COS, CS.sub.2, or a combination of COS and CS.sub.2 are
present in the gas produced by a thermal conversion process such as
a pyrolysis process or a gasifier, COS and CS.sub.2 may be shifted
to H.sub.2S using a shift reactor according to the Reactions 20-21:
COS+H.sub.2O.fwdarw.H.sub.2S+CO.sub.2 (20),
CS.sub.2+2H.sub.2O.fwdarw.2H.sub.2S+CO.sub.2 (21), which may be
followed by Reactions 15 and 19.
[0051] The shift reactions illustrated by Reactions 20 and 21 may
be promoted by Ca, Mg, NA, K, Cu, Fe, Al, and other elements or
mineral compounds contained in the oil shale or oil shale
sorbents.
[0052] The shale minerals, such as the carbonate compounds, may be
calcined by heating the oil shale to a temperature greater than or
equal to approximately 450.degree. C. The adsorption of the
sulfur-containing pollutant may occur in a location of the
combustion chamber where the temperature is relatively hot. The
temperature may be sufficiently high to achieve favorable reaction
of the sulfur-containing pollutant with the alkali compounds,
alkaline-earth compounds, or other metal oxides present in the oil
shale to produce sulfate or sulfide compounds. However, the
temperature may be less than the dissociation temperatures of the
compounds. To achieve reaction between the shale minerals and the
H.sub.2SO.sub.4, SO.sub.2, SO.sub.3, H.sub.2S, COS, or CS.sub.2, a
temperature ranging from greater than or equal to approximately
450.degree. C. to less than approximately 1150.degree. C. may be
used.
[0053] The shale minerals, such as the carbonate or oxide
compounds, may also be used to remove HCl and Cl.sub.2 according to
the example chemistries shown in Reactions 22 and 23:
CaO+2HCl.fwdarw.CaCl.sub.2+H.sub.2O (22),
CaO+Cl.sub.2.fwdarw.CaCl.sub.2+1/2O.sub.2 (23).
[0054] While the reactions shown above are between calcium oxide
and chlorine-containing compounds, similar reactions may occur
between HCl or Cl.sub.2 and Mg, Na, K, Fe, or Zn. Similar reactions
may also occur with fluorine, fluorine-containing compounds,
iodine, iodine-containing compounds, bromine, bromine-containing
compounds, phosphate, and phosphate-containing compounds. The
adsorption of fluorine, fluorine-containing compounds, iodine,
iodine-containing compounds, bromine, bromine-containing compounds,
phosphate, and phosphate-containing compounds may occur in a
location of the thermal conversion process chamber where the
temperature is relatively hot. The temperature may be sufficiently
high to achieve favorable reaction of the fluorine,
fluorine-containing compounds, iodine, iodine-containing compounds,
bromine, bromine-containing compounds, phosphate, and
phosphorus-containing compounds with the alkali compounds,
alkaline-earth compounds, or other metal oxides present in the oil
shale to produce halogen or phosphorus compounds. However, the
temperature may be less than the dissociation temperatures of the
compounds. For example, for the reaction of HCl with the shale
minerals, the temperature of the reaction may be maintained from
greater than or equal to approximately 450.degree. C. to less than
approximately 1150.degree. C.
[0055] In processes such as those describe in U.S. patent
application Ser. No. 11/004,698, the oil shale used in and fed to
combustion chambers may include ore that is obtained from a
conventional oil shale mine and pulverized into particles. The oil
shale may be obtained from a source, such as mines in Utah,
Colorado, or Wyoming that yield approximately 10 gallons of oil per
ton of ore to approximately 80 gallons of oil per ton of ore. Other
sources of oil shale around the world may also be used, each of
which contain varying concentrations of kerogen and other minerals.
The oil shale may initially be ground or milled to a desired coarse
particle size of less than or equal to approximately 5 cm
(approximately 2 inches). The oil shale may be ground using
conventional techniques, similar to the crushing and grinding
techniques used in coal mining. The oil shale particles may be
further pulverized into microsize particles having a particle size
ranging from approximately 2 .mu.m to approximately 150 .mu.m,
which are introduced into the combustion chamber. The microsize
particles may be pulverized, classified, and entrained in an air
stream using conventional techniques, similar to the techniques for
pulverizing, classifying, and entraining coal in an air stream. As
such, existing coal pulverizers, classifiers, and injectors may be
used to produce and inject the oil shale particles into the
combustion chamber. The oil shale particles may be unreacted, in
that the oil shale particles have not been pyrolyzed or
devolatilized. However, oil shale retort (devolatilized oil shale
particles) may also be used in the combustion chamber.
[0056] To decrease the amount of the pollutants produced by
combustion of a primary fuel, oil shale particles may be introduced
into a combustion chamber, for example a pulverized coal combustor
("PCC"), a furnace, a boiler, fluidized bed combustor or gasifier,
a circulating bed combustor or gasifier, a staged reactor combustor
or gasifier, an entrained-flow combustor or gasifier, an offgas
duct, an offgas cleanup transport reactor, a packed-bed combustor
or gasifier, a rotary-bed combustor or gasifier, or calcining
devices such as a cement kiln. Oil shale particles may also be used
in a metallurgical process, such as during the production of iron
ore or the smelting or refining of metals. A combustion chamber may
be configured to combust coal or other fossil fuels, biomass, MSW,
RDF, or other carbon-containing feedstock materials. While some
embodiments herein describe using the oil shale particles in a PCC,
oil shale particles may be used in other types of thermal
conversion chambers as long as the thermal conversion chamber is
capable of producing the temperatures at which the reactions with
the oil shale particles occur. In addition, while the embodiments
herein describe using coal as a primary fuel, other fuels, such as
oil, natural gas, oil shale, oil sands, and other carbon-containing
fuel feedstock materials (for example: forestry industry products,
byproducts, and residues; agriculture crops, byproducts, and
residues; animal wastes and carcasses; municipal solid waste,
sewage sludge solids, construction and demolition debris, waste
tires, and other forms of refuse-derived fuel) may be used.
[0057] PCCs are designed to burn coal as a primary fuel and to
convert the chemical energy (enthalpy) of the burning coal into
heat, which is transferred to steam tubes to produce super-heated,
high pressure steam. PCCs typically produce from approximately 50
MW.sub.e to approximately 1000 MW.sub.e of energy. PCCs typically
comprise a long, vertical burner box that is lined with the steam
tubes or has pendant arrangements of the steam tubes. PCCs are
known in the art and, therefore, are not discussed in further
detail herein. A schematic illustration of a PCC 100 into which oil
shale particles 120 may be introduced is shown in FIG. 1. The PCC
100 includes a burner zone 106, a superheater zone 108, a reheat
zone 110, an economizer zone 112, an air preheat zone 114, and a
gas cleaning unit 116. To decrease the pollutants produced by
combusting the coal in the PCC 100, the temperature in each of
these zones may be controlled to achieve the desired reactions
between the pollutants and the kerogen and between the pollutants
and the sorbent particulates.
[0058] Pulverized coal 128 may be introduced into the burner zone
106 of the PCC 100 and combusted with air 130. An amount of
pulverized coal 128 added to the PCC 100 may depend on an
efficiency of the PCC 100 and its desired power output. A feed rate
at which the pulverized coal 128 is introduced into the PCC 100 may
be calculated based on the efficiency of the PCC 100 and desired
power output, as known in the art. The pulverized coal 128 may be
entrained with the air 130 and injected into the PCC 100 through
multiple burners (not shown), which are also referred to in the art
as burner registers or burner boxes. Alternatively, the pulverized
coal 128 may be injected into the burner zone 106 through primary
ports (not shown). The air 130 may be injected with the pulverized
coal 128 or may be injected through secondary or tertiary ports
(not shown). To combust the pulverized coal 128, the burner zone
106 may be maintained at a temperature ranging from approximately
1085.degree. C. to approximately 1625.degree. C. (approximately
2000.degree. F. to approximately 3000.degree. F.). Upon combustion,
nitrogen present in the pulverized coal 128 and the air 130 may be
converted to nitrogen-containing pollutants. Sulfur in the
pulverized coal 128, such as organically-bound sulfur or inorganic
or pyrite-phase sulfur, may be released and oxidized or converted
to the sulfur-containing pollutants, such as H.sub.2SO.sub.4,
SO.sub.2, SO.sub.3, H.sub.2S, COS, CS.sub.2, or mixtures thereof.
Chlorine in the pulverized coal 128 may be converted to HCl,
Cl.sub.2, or other volatile chlorine compounds. Iodine in the
pulverized coal 128 may be converted to HI, I.sub.2, or other
volatile iodine compounds while fluorine in the pulverized coal 128
may be converted to HF, F, or other volatile fluoride compounds.
Bromine in the pulverized coal 128 may be converted to HBr, Br, or
other volatile bromide compounds. Phosphorus in the pulverized coal
128 may be converted to phosphorous containing compounds. Mercury
present in the pulverized coal 128 may be released as Hg.degree. or
HgCl.sub.2. Arsenic, lead, beryllium, and other toxic metals may be
released as volatile and semi-volatile compounds.
[0059] The oil shale particles 120 may be entrained and injected
into the PCC 100 in at least one of the burner zone 106, the
superheater zone 108, and the reheat zone 110, depending on the
temperature profile of the PCC 100 and the properties of the oil
shale. For the sake of clarity and simplicity, the oil shale
particles 120 are shown in FIG. 1 as being injected into the
superheater zone 108. The oil shale particles 120 may be injected
into the PCC 100 through multiple burners (not shown), primary
ports (not shown), or secondary or tertiary ports (not shown). The
oil shale particles 120 are not injected into a zone of the PCC 100
where the oil shale particles 120 would fuse and slag since this
may affect the ability of the oil shale particles 120 to capture
the pollutant in later stages of the gas exit path. A feed rate at
which the oil shale particles 120 are introduced into the PCC 100
may depend on the efficiency of the sorbent reactions. This feed
rate may be determined as known in the art. In one embodiment, the
oil shale particles 120 are injected into an upper region of the
burner zone 106 or a lower region of the superheater zone 108. Oil
shale retort (devolatilized oil shale particles) may also be
injected into the reheat zone 110. After being injected into the
PCC 100, the oil shale particles 120 may begin to devolatilize and
release the kerogen, which reacts with the nitrogen-containing
pollutant as described in Reactions 1-4. The temperature in at
least one of the burner zone 106, the superheater zone 108, and the
reheat zone 110 may be maintained so that it is favorable to
chemical reduction of the nitrogen-containing pollutants to
N.sub.2, CO.sub.2, and H.sub.2O, significantly decreasing the
amount of the nitrogen-containing pollutants that exit the PCC
100.
[0060] The shale minerals produced after the kerogen is released
may react with gaseous H.sub.2SO.sub.4, SO.sub.3, SO.sub.2, HCl,
H.sub.2S, COS, CS.sub.2, or mixtures thereof as described in
Reactions 9-17. Calcium oxide, magnesium oxide, iron oxide, and
other metal oxides from the oil shale may react and capture the
H.sub.2SO.sub.4, SO.sub.3, SO.sub.2, HCl, H.sub.2S, COS, CS.sub.2,
or mixtures thereof when the reaction kinetics and thermodynamics
are favorable for the formation of CaSO.sub.4 or CaS. Generally,
favorable reactions may occur at a temperature ranging from
approximately 450.degree. C. to approximately 1125.degree. C.
Temperatures within this range may occur in at least one of the
superheater zone 108, the reheat zone 110, and the economizer zone
112. Therefore, the capture of the HCl, H.sub.2SO.sub.4, SO.sub.3,
SO.sub.2, H.sub.2S, COS, CS.sub.2, or mixtures thereof may occur as
the oil shale particles 120 pass out of the superheater zone 108
and into the reheat zone 110 and the economizer zone 112. The
capture of the HCl, H.sub.2SO.sub.4, SO.sub.3, SO.sub.2, H.sub.2S,
COS, CS.sub.2, or mixtures thereof may also continue into a lower
portion of the air preheat zone 114. A residence time or contact
time between the shale minerals and the pollutants may be greater
than or equal to approximately 5 seconds to capture these
pollutants.
[0061] Mercury or mercuric chloride may react with the shale
minerals or char particles by two mechanisms: physical absorption
or chemical adsorption. As the shale minerals or char particles
pass into portions of the PCC 100 having cooler temperatures,
mercury or mercuric chloride may be adsorbed or absorbed, as
described in Reactions 5-8. For instance, mercury or mercuric
chloride may be adsorbed or absorbed by the sorbent particulates in
the air preheat zone 114 or the gas cleaning unit 116. These
reactions may occur when the temperature drops below approximately
200.degree. C. (approximately 392.degree. F.). Since temperatures
within this range may occur in the air preheat zone 114 or the gas
cleaning unit 116, these portions of the PCC 100 may be the most
effective in removing mercury or mercuric chloride. To effectively
capture these pollutants, the contact time between the sorbent
particulates and the mercury or mercuric chloride may be greater
than approximately 30 seconds. Such long contact times may be
achieved in the gas cleaning unit 116.
[0062] The hot gases and entrained flyash particles produced by
combusting the pulverized coal 128 may exit the burner zone 106 and
pass into the superheater zone 108, where the hot gases contact the
steam tubes 140. The steam tubes 140 extract heat from the hot
gases and increase the steam temperature. In the superheater zone
108, the temperature of the hot gases ranges from approximately
975.degree. C. to approximately 1320.degree. C. (from approximately
1800.degree. F. to approximately 2400.degree. F.). The hot gases
and entrained flyash particles may pass into the reheat zone 110,
which is a transition zone between the superheater zone 108 and the
economizer zone 112. Steam tubes 140 may also be present in the
reheat zone 110. The temperature in the reheat zone 110 may vary
from approximately 650.degree. C. to approximately 980.degree. C.
(from approximately 1200.degree. F. to approximately 1800.degree.
F.). The hot gases may be cooled in the economizer zone 112 by
additional steam tubes 140. The temperature of the hot gases in the
economizer zone 112 may range from approximately 535.degree. C. to
approximately 650.degree. C. (from approximately 1000.degree. F. to
approximately 1200.degree. F.).
[0063] The gases that exit the economizer zone 112 are referred to
in the art as flue gas. At this point, the flue gas may include
air, combustion products, water vapor, carbon dioxide, mercury, and
particulate matter. The flue gas may be substantially free of the
nitrogen-containing pollutants, the sulfur-containing pollutants,
and HCl because these pollutants are removed in the burner zone
106, the superheater zone 108, or the reheat zone 110. The flue gas
may be further cooled by gas-to-gas heat exchangers (not shown) in
the air preheat zone 114 to preheat the incoming combustion air.
The temperature of the flue gas in the air preheat zone 114 may
range from approximately 120.degree. C. to approximately
230.degree. C. (from approximately 250.degree. F. to approximately
450.degree. F.). The flue gas 150 may flow into the gas cleaning
unit 116, such as the baghouse or electrostatic precipitator (ESP),
to remove the particulate matter, such as the flyash 152. The
flyash 152 may be collected on a filter in the gas cleaning unit
116.
[0064] Since introducing the oil shale particles 120 into the PCC
100 utilizes many existing coal handling and processing
technologies, this method of decreasing levels of pollutants in the
flue gas 150 may be readily implemented in existing PCCs because it
does not require the installation of new equipment. The use of the
oil shale particles 120 may also be incorporated into future PCC
designs without significant costs.
[0065] As described above, the oil shale particles 120 may be used
to decrease the amount of a single type of pollutant, such as a
nitrogen-containing pollutant, H.sub.2SO.sub.4, SO.sub.3, SO.sub.2,
H.sub.2S, COS, CS.sub.2, mercury, or mercury chloride, in the flue
gas 150. The oil shale particles 120 may also be used to decrease
the amount of different types of pollutants in the flue gas 150.
Therefore, the oil shale particles 120 may provide multi-pollutant
control. In addition, since pyrolization of the oil shale particles
120 produces porous sorbent particulates, higher pollutant loadings
may be achieved. As such, lower injection rates of the oil shale
particles 120 may be used, which decreases the amount of solid
material for disposal. While the oil shale particles 120
effectively decrease the pollutant levels in the flue gas 150, the
oil shale particles 120 may also be used in combination with other
technologies to further decrease the amounts of the pollutants,
such as the LIMB, LIDS, SNCR, and NO.sub.x reburning
technologies.
[0066] In addition to removing the pollutants, the oil shale
particles 120 may add enthalpy (i.e., heating value) since the oil
shale particles 120 are combusted along with the primary fuel. The
char particles and the heavy and light hydrocarbons, which are
produced during the combustion of the oil shale, may be fully or
partially combusted to provide additional heat, as shown by
Reactions 24-31:
C.sub.xH.sub.y+(x+y/4)O.sub.2.fwdarw.xCO.sub.2+y/2H.sub.2O (24),
CO+1/2O.sub.2.fwdarw.CO.sub.2 (25),
C.sub.xH.sub.y+x/2O.sub.2.fwdarw.xCO+y/2H.sub.2 (26),
C.sub.xH.sub.y+xH.sub.2O.fwdarw.xCO+(x+y/2)H.sub.2 (27), Char
carbon+O.sub.2.fwdarw.CO.sub.2 (28), Char
carbon+1/2O.sub.2.fwdarw.CO (29), Char carbon+CO.sub.2.fwdarw.2CO
(30), Char carbon+H.sub.2O.fwdarw.CO+H.sub.2 (31).
[0067] While not all of Reactions 24-31 are exothermic, the
reactions either produce heat or produce reactive gases that may be
used to produce heat. The oil shale may provide a net positive heat
of combustion that ranges from approximately 4.7 MJ/kg (or
approximately 2,000 BTU/lb) to approximately 9.3 MJ/kg (or
approximately 4,000 BTU/lb). The energy provided by the combustion
of the oil shale may offset the heat lost due to the pollutant
sorption reactions.
[0068] The unreacted heavy and light hydrocarbons may be completely
reacted in the superheater zone 108 or the reheat zone 110 with
excess oxygen or air (not shown) that is introduced. In addition,
supplementary oxygen (not shown) may be added to the superheater
zone 108 or the reheat zone 110 as needed to combust the heavy and
light hydrocarbons. Most combustion chambers are equipped with soot
blowing air injectors or air lances, which may be used to adjust
the oxygen concentration to achieve complete combustion of the
heavy and light hydrocarbons.
[0069] Using the oil shale particles 120 in the combustion process
may also improve the disposal of flyash produced during the
combustion of the primary fuel. The combustion of the oil shale may
also produce flyash 152 and slag 154 (coal and oil shale byproduct
mineral matter). The oil shale particles 120 may be used to make
the flyash 152 or the slag 154 suitable for disposal in a landfill.
During combustion, the oil shale particles 120 are calcined and
converted to a pozzolanic material that includes oxide compounds.
The pozzolanic material may encapsulate and immobilize the metals,
slag 154, and flyash 152 produced during the combustion. The flyash
152 may also be used as a road bed material or a construction
material.
[0070] Not only may oil shale be used as an agent to reduce
pollution in a combustion process, metal pyrolysis process,
calcination process, or other processes, devolatilized oil shale
may also be used as a pollutant control material. Kerogen in oil
shale may be reacted and devolatilized in an ex-situ thermal
conversion process to produce shale minerals and char particles and
a combustible kerogen-based fuel. The shale minerals and char
particles may be fed to a separate, coupled thermal conversion
process, such as, but not limited to, a combustion process, a
cement kiln, or ore smelting or metals refining processes, to
absorb or adsorb pollutants in much the same way that the shale
minerals produced by the addition of oil shale to a combustion
process absorb and adsorb pollutants. In addition, the
kerogen-based fuel may also be fed to the process to act as a
reduction agent to remove pollutants. Alternatively, the
kerogen-based fuel may be used as a heating fuel or may be
processed into useful fuel products.
[0071] Embodiments of the invention involve the devolatilization of
kerogen from oil shale to produce a shale sorbent and a
kerogen-based fuel. The devolatilization of kerogen from oil shale
may be controlled such that desired characteristics of shale
sorbent and kerogen released from the oil shale may be
produced.
[0072] According to certain embodiments of the invention, the
gasification, pyrolysis, devolatilization, or retorting of oil
shale may be performed to produce a solid ash, or shale sorbent,
having pollutant sorbent qualities. Oil shale may be introduced to
a gasification process to controllably release kerogen from the oil
shale. The controlled release of kerogen from the oil shale may
result in the formation of a solid ash having pollutant control
characteristics. For instance, the shale sorbent may act as a
sorbent for pollutants or as a reductant for pollutants.
[0073] For example, oil shale may be introduced to a gasification
process where the oil shale undergoes gasification to release
kerogen from the oil shale. The gasification may be controlled to
release large amounts of kerogen stored in the oil shale.
Devolatilized oil shale exits the gasification process as a shale
sorbent. The shale sorbent may be ground or otherwise processed to
produce a shale sorbent having the desired size for use with
processing operations to adsorb or absorb pollutants or to
otherwise be used as a pollution sorbent. In some embodiments, the
shale sorbent may be fed to a process to control pollutants in the
process or contacted with process products to reduce pollutants
therein.
[0074] According to other embodiments of the invention, the
gasification of oil shale may be controlled to produce solid
particles of pollutant sorbent, wherein the particles include fixed
carbon which may assist in the absorption or adsorption of
pollutants. The gasification of the oil shale may be controlled to
ensure that portions of the oil shale are charred to produce a
shale sorbent having an amount of carbon contained within or on the
shale sorbent particles. The charred shale sorbent may be collected
and used as a pollutant control sorbent.
[0075] According to still other embodiments of the invention, the
gasification of oil shale may produce a reducing gas that may be
used for pollutant control. For example, a gas that may be used in
the reduction of NO.sub.x emissions may be produced according to
embodiments of the invention. The devolatilization of kerogen from
oil shale introduced to a gasification process to produce a
reducing gas may include control and optimization of the
devolatilization process to produce a gas having high quantities of
reduced forms of carbon, such as CH.sub.4, C.sub.2H.sub.4,
C.sub.2H.sub.6, C.sub.3H.sub.8, and low quantities of heavy
hydrocarbons. The reducing gas may be fed directly to a process or
process product streams where it may be used as a reducing gas or
it may be stored according to conventional methods and used with
other processes.
[0076] In other embodiments of the invention, a hydrocarbon gas may
be produced by the gasification of oil shale. The devolatilization
of kerogen from oil shale may be controlled to produce hydrocarbon
gases. The devolatilization conditions may be controlled such that
particular amounts of desired hydrocarbons are produced from the
gasification process. In this manner, hydrocarbon gases may be
formed that can be separated and marketed as synthetic natural
gases or that can be altered to produce synthetic gases and gas
products. Hydrocarbon gas streams may also be produced which may be
cooled, condensed, and then distilled, cracked, or hydrogenated to
produce higher value synthetic petroleum crude products.
[0077] FIG. 2 illustrates a simplified material flow diagram of a
pyrolysis or gasifier system that may be used to carry out
embodiments of the invention. As illustrated in FIG. 2, ground oil
shale 210 may be introduced into the gasifier 200 with steam 212
and one or more oxidizer gases 214. The gasification of the oil
shale 210 introduced into the gasifier 200 may cause the
devolatilization of kerogen from the oil shale 210, which may
result in the production of a pyrolysis gas 220 and a shale sorbent
230. The pyrolysis gas 220 may be removed from the gasifier 200 and
stored, burned, utilized, or otherwise processed as desired.
Similarly, the shale sorbent 230 may be used as a pollution sorbent
according to embodiments of the invention or may be used with other
processes.
[0078] The gasifier 200 represented by the block diagram
illustrated in FIG. 2 may include any type of gasifier 200 or
thermal conversion unit capable of devolatilizing the kerogen from
oil shale and capable of calcining the shale to produce a shale
sorbent. For example, conventional fixed-bed gasifiers, fluid-bed
gasifiers, or entrained-flow gasifiers may be used with embodiments
of the invention. Other conventional gasifiers or rotary-driven
pyrolysis operations may also be used with embodiments of the
invention.
[0079] According to those embodiments of the invention where the
oil shale 210 is being devolatilized of kerogen to produce a shale
sorbent 230 to capture pollutants from other processes, a fixed-bed
or bubbling fluidized-bed gasifier may be used to gasify the oil
shale 210. The use of such a gasifier 200 may even be preferred if
the oil shale 210 particles being devolatilized of kerogen include
crushed, coarse oil shale 210 particles with sizes, for example,
between about 0.5 to 10 mm in diameter. The use of a fixed-bed or
bubbling fluidized-bed gasifier may help to produce high quality
shale sorbent 230 wherein most of the kerogen contained in the oil
shale 210 is removed from the oil shale 210 within the gasifier
200. The shale sorbent 230 produced in such a manner may have a
high "loss on ignition" value. Other types of gasifiers may also be
used to produce such shale sorbents 230.
[0080] In those embodiments of the invention where the oil shale
210 includes a finely ground oil shale 210, such as oil shale
having particle sizes between about 0.001 to about 0.01 mm
diameter, an entrained gasifier may be used as gasifier 200 to
devolatilize kerogen from the oil shale 210. For example, oil shale
210 particles having a diameter of between about 0.001 and about
0.01 millimeters may be introduced into an entrained gasifier 200
to devolatilize kerogen therefrom. The pyrolysis gases 220 produced
from the devolatilization process may be burned within the gasifier
200 to aid in the devolatilization process.
[0081] The choice of gasifiers 200 for use with embodiments of the
invention may also depend upon the pyrolysis gases 220 desired from
the process. For example, when the pyrolysis gases 220 are to be
burned or otherwise used as reducing gases to reduce the presence
of NO.sub.x pollutants or other pollutants in other gas streams,
the gasifier 200 or other thermal conversion process may be
selected to optimize the production of reduced forms of carbon,
such as CH.sub.4 and C.sub.2H.sub.4.
[0082] The production of heavy hydrocarbons in a pyrolysis gas may
not be desired; therefore, a gasifier 200 or other thermal
conversion process may be selected to limit the production of such
heavy hydrocarbons. For instance, the presence of heavy
hydrocarbons in a feed stream from a gasifier 200 to a secondary
process may cause unwanted condensation of the feed stream. In some
embodiments, the pyrolysis gas 220 exiting the gasifier 200 or
other thermal conversion process may be routed to a tar cracker
(not shown) or a gas reformer (not shown) to further breakdown or
otherwise remove the heavy hydrocarbons from the pyrolysis gas 220.
Conventional processes may be used to alter or change the heavy
hydrocarbons in a pyrolysis gas 220 stream before the pyrolysis gas
220 stream is routed to another process.
[0083] In other embodiments of the invention, the production of
reduced forms of hydrocarbons in the pyrolysis gas 220 may not be
desirable. For example, in syngas and synfuels production
processes, the amount of hydrocarbons in the pyrolysis gas 220 is
preferably minimized. Instead, the production of carbon monoxide
("CO") and hydrogen ("H.sub.2") is preferably maximized. Therefore,
a gasifier 200 or other thermal conversion process may be selected
to maximize the production of carbon monoxide and hydrogen during
the pyrolysis of the oil shale 210 in the gasifier 200. In some
embodiments, the gasifier 200 may even be selected or operated to
produce an optimized ratio of carbon monoxide and hydrogen for
Fischer-Tropsch synthetic fuel production processes.
[0084] The introduction of oil shale 210, steam 212, and oxidizer
gas 214 to a gasifier 200 as illustrated in FIG. 2 may result in a
number of different reactions within the gasifier 200 or other
thermal conversion process. For example, when oil shale is heated
in the gasifier 200 or other thermal conversion process, shale
minerals, char particles, and kerogen are produced. The shale
minerals and char particles make up the shale sorbent 230. The
production of the shale minerals, char particles, and kerogen is
similar to the reaction that occurs when oil shale 210 is
introduced directly into a combustion chamber or other thermal
conversion process, such as a combustion chamber of a pulverized
coal boiler. The formation of the shale sorbent 230 and kerogen may
be represented by Reaction 32: oil shale+heat.fwdarw.shale
sorbent+kerogen (32). A temperature of greater than or equal to
approximately 200.degree. C. may be used to pyrolyze the oil shale
210 in a gasifier 200 or other thermal conversion process. As the
oil shale 210 is heated, the heat may cause the kerogen to
depolymerize and devolatilize while the shale minerals may be
calcined. The extent of depolymerization, devolatilization,
pyrolysis, and char formation of the oil shale 210 may vary
depending on particle heat up rates, particle temperature,
surrounding gas temperature, and the amount of time that the oil
shale 210 is heated in the gasifier 200 or other thermal conversion
process. When the kerogen is devolatilized or released from the oil
shale, a porous matrix of oxides, carbonates, or silicates may
remain including, but not limited to, silicon dioxide
("SiO.sub.2"), and oxides, and carbonates of calcium ("Ca"),
magnesium ("Mg"), sodium ("Na"), potassium ("K"), iron ("Fe"), or
zinc ("Zn"). For the sake of example only, the shale minerals may
include, but are not limited to, calcium oxide, magnesium oxide,
iron oxide, calcium carbonate, or mixtures thereof. The char
particles or particles of residual carbon may also remain after the
kerogen is devolatilized from the oil shale 210. The shale sorbent
230 comprises the shale minerals and char particles. The shale
sorbent 230 may include porous particles that have an increased
surface area. As such, the shale sorbent 230 may have an increased
adsorption or absorption capability relative to that of the oil
shale 210 and may be used to adsorb or absorb mercury and other
pollutants. In addition, the shale sorbents 230 may be porous,
allowing pollutants to diffuse into the shale sorbent 230 and react
with the oxides, carbonates, and silicates therein.
[0085] The introduction of steam 212 into the gasifier 200 or other
thermal conversion process may react with the char particles of the
shale sorbent 230, forming activated carbon within, or on, the
shale sorbent 230 as represented by Reaction 33: oil
shale+heat.fwdarw.shale minerals+char particles+kerogen+hydrocarbon
derivatives (33).
[0086] Kerogen in the oil shale 210 may be released within the
gasifier 200. Kerogen released from the oil shale 210 may provide a
source of a reductant used to reduce pollutants in other processes.
As shown in Reaction 34, the kerogen may be exposed to additional
heat to crack or scission the kerogen, forming light and heavy
hydrocarbons: kerogen+heat+radicals.fwdarw.heavy and light
hydrocarbons (C.sub.xH.sub.y)+CO+H.sub.2+ (34), where x and y
depend on the carbon and hydrogen ratio in the kerogen and temporal
conditions. For instance, x may range from 1 to 7 for a light
hydrocarbon, from 8 to 12 for an intermediate hydrocarbon, or from
12 to 42 for a heavy hydrocarbon. In correlation, y may range from
1 to 90 and is typically equal to two times x for a given
hydrocarbon. A temperature of greater than or equal to
approximately 350.degree. C. may be used to crack and scission the
polymeric kerogen. The heavy hydrocarbons are thus progressively
converted to lighter hydrocarbons. The presence of steam helps
crack and reform the heavy hydrocarbons.
[0087] Embodiments of the invention may be incorporated with any
pollution producing processes to reduce the amount of pollution
produced in a process. For example, a gasifier 200 for converting
oil shale 210 to pyrolysis gases 220 and shale sorbent 230 may be
incorporated with a pulverized coal boiler, a cement production
process, a synfuels or syngas production process, a metallurgy
pyrolysis process, a pulverized coal combustor, a furnace, a
boiler, fluidized bed combustor or gasifier, a circulating bed
combustor or gasifier, a staged reactor combustor or gasifier, an
entrained-flow combustor or gasifier, an offgas duct, or an offgas
cleanup transport reactor. The embodiments of the invention may be
used to produce a shale sorbent 230 for absorbing or adsorbing
pollutants produced in the respective processes or to produce a
kerogen-based fuel that may be used with the processes. Embodiments
of the invention are not limited to these recited uses and it is
understood that a gasifier for producing shale sorbents 230,
pyrolysis gases 220, or pollutant reduction gases may be
incorporated with many conventional processes and especially
processes which produce pollutants which are desired to be
controlled.
[0088] The incorporation of a gasifier 200 or other thermal
conversion process according to embodiments of the invention with a
pollutant forming process is illustrated in FIG. 3. As illustrated,
a gasifier 200 or other thermal conversion process may be
incorporated with a pulverized coal boiler system 300. The
incorporation of a gasifier 200 or other thermal conversion process
according to embodiments of the invention with a pulverized coal
boiler system 300 may be used to provide shale sorbent 230,
pyrolysis gas 220, or reduction gases to the pulverized coal boiler
system 300. Although the system illustrated in FIG. 3 includes a
gasifier 200 or other thermal conversion process incorporated with
a coal boiler system 300, it is understood that embodiments of the
invention may be incorporated with many different systems where
pollutants are generated and where reduction of such pollutants is
desired.
[0089] As illustrated in FIG. 3, a conventional coal boiler system
300 may include a burner zone 306, a superheater zone 308, a reheat
zone 310, an economizer zone 312, an air preheat zone 314, and a
gas cleaning unit 316. Coal 328, such as pulverized coal, may be
introduced into the burner zone 306 where it may undergo
combustion, forming gasses and slag 354. Air 330 may also be
introduced into the burner zone 306 to facilitate the combustion of
the coal 328 in the coal boiler system 300. The introduction of air
330 may include the introduction of combustion air, primary air,
and infiltration air as known with conventional coal boiler systems
300. Slag 354 produced in the burner zone 306 may be removed from
the coal boiler system 300 as conventionally known.
[0090] The coal 328 may be combusted in the burner zone 306, which
may be maintained at a temperature of about 800.degree. C. to about
1650.degree. C. Reactions within the burner zone 306 include
reactions related to the combustion of coal 328, such as Reactions
35-44: C+O.sub.2.fwdarw.CO.sub.2 (35),
2H+1/2O.sub.2.fwdarw.H.sub.2O (36), N+1/2O.sub.2.fwdarw.NO (37),
2N.fwdarw.N.sub.2 (38), 2Cl+H.sub.2O.fwdarw.2HCl+1/2O.sub.2 (39),
S+O.sub.2.fwdarw.SO.sub.2 (40), 2O.fwdarw.O.sub.2 (41),
2FeS.sub.2+11/2O.sub.2.fwdarw.Fe.sub.2O.sub.3+4SO.sub.2 (42),
HgS.fwdarw.Hg.degree.+SO.sub.2 (43)
Carbonates.fwdarw.Oxide+CO.sub.2 (44). As indicated by the
reactions which occur during the combustion of coal 328, pollutants
such as SO.sub.2, NO, and HCl may be produced. Other pollutants may
also be formed. The pollutants are undesirable and may be removed
by the burning of pyrolysis gases 220 from a gasifier 200 or other
thermal conversion process according to embodiments of the
invention or by the introduction of shale sorbent 230 into the coal
boiler system 300.
[0091] Gases and particulates formed during the combustion of the
coal 328 exit the burner zone 306 and enter the superheater zone
308. The gases and particulates from the superheater zone 308 pass
into the reheat zone 310 and then into the economizer zone 312
before entering the air preheat zone 314. Temperatures in each of
the zones may be controlled by the presence of steam tubes 340 in
each of the zones. Flue gases 350 exiting the air preheat zone 314
may be fed to a gas cleaning unit 316 such as a baghouse or
electrostatic precipitator (ESP). Particulate matter, such as
flyash 352, may be collected from the gas cleaning unit 316 and the
waste gasses from the coal boiling system 300 may be released or
fed to other gas cleaning processes.
[0092] According to embodiments of the invention, pollutants
produced in the burner zone 306 and throughout the remainder of the
coal boiler system 300 may be reduced by the introduction of shale
sorbent 230 or pyrolysis gases 220 into the coal boiler system 300
or into product streams produced by the coal boiler system 300. For
example, NO.sub.x pollutants formed in the burner zone 306 of the
coal boiler system 300 may be reduced by the simultaneous burning
of pyrolysis gases 220 formed from the gasification of oil shale
210 in the burner zone 306. The pyrolysis gases 220 from a gasifier
200 may be fed from the gasifier 200 to an input in the burner zone
306 of the coal boiler system 300. When fed or otherwise injected
into the burner zone 306, the pyrolysis gases 220 may be oxidized
by the presence of NO.sub.x, thereby reducing the
nitrogen-containing pollutants to N.sub.2 or other
nitrogen-containing compounds, carbon dioxide ("CO.sub.2"), and
water ("H.sub.2O") in accordance with Reactions 3 and 4 previously
described.
[0093] Additional oxidizing reactions may also occur with the
introduction of pyrolysis gas 220 to the burner zone 306. For
example, Reactions 45 and 46 may occur within the burner zone 306
in addition to the reduction of NO.sub.x shown in Reactions 3 and
4: C.sub.xH.sub.y+(x+y/4)O.sub.2.fwdarw.xCO.sub.2+y/2H.sub.2O (45),
CO+1/2O.sub.2.fwdarw.CO.sub.2 (46), where x may range from 1 to 7
for a light hydrocarbon, from approximately 8 to 12 for an
intermediate hydrocarbon, or from approximately 13 to 42 for a
heavy hydrocarbon. In correlation, y may range from 1 to 90 and is
typically equal to nominally two times x for a given hydrocarbon.
In some instances, the pyrolysis gases 220 may be introduced into
the burner zone 306 in two or more locations. The introduction of
pyrolysis gases 220 in more than one location may facilitate both
the reduction reactions of NO.sub.x pollutants as shown by
Reactions 3 and 4 and the oxidation reactions of Reactions 45 and
46. An illustrative example of multiple pyrolysis gas 220 feed
inputs into the burner zone 306 is represented by the two pyrolysis
gas 220 feed inputs 220(a) and 220(b) illustrated in FIG. 3. As
illustrated, one or more of the pyrolysis gas 220 feed inputs
220(b) may be located on a dividing zone between the burner zone
306 and the superheater zone 308 or may be located at the entrance
of the superheater zone 308 from the burner zone 306.
[0094] Gasses and particulate matter from the burner zone 306 may
pass into the superheater zone 308 where additional reactions
occur. The superheater zone 308 may be maintained at between about
675.degree. C. and about 1320.degree. C. Steam tubes 340 may be
positioned in the superheater zone 308 to provide heat as known
with conventional coal boiler systems 300.
[0095] Pollutants in the gases and particulate matter produced in
the burner zone 306 may be at least partially removed by adsorption
or absorption of the pollutants by shale sorbent 230 introduced
into the superheater zone 308. Shale sorbent 230 from the gasifier
200 may be introduced into the superheater zone 308 in one or more
locations. For instance, shale sorbent 230 from the gasifier 200
may be introduced into the superheater zone 308 of the coal boiler
system 300 to absorb and adsorb pollutants transferred from the
burner zone 306 to the superheater zone 308. The shale sorbent 230
may be ground to a desired size and entrained in air such that it
may be injected into the coal boiler system 300. An example of the
introduction of shale sorbent 230 is illustrated in FIG. 3, where
the shale sorbent 230 from the gasifier 200 is injected into the
superheater zone 308 at inlet 230(a). Although only one shale
sorbent 230 inlet 230(a) into the superheater zone 308 is
illustrated, it is understood that one or more inlets may be used
and that the positioning of the inlets to feed shale sorbent 230
into the superheater zone 308 may be customized to maximize or
customize the removal of pollutants from the gases and particulate
matter in the superheater zone 308.
[0096] Pollutants passed from the superheater zone 308 to the
reheat zone 310 of the coal boiler system 300 may also be at least
partially removed by the introduction of shale sorbent 230 into the
reheat zone 310. Shale sorbent 230 from a gasifier 200 may be
introduced into the reheat zone 310 through one or more inlets
230(b) in much the same manner that it may be introduced into the
superheater zone 308. Shale sorbent 230 may also be introduced into
the economizer zone 312 or air preheat zone 314 to help remove
pollutants from the gases and particulates in the coal boiler
system 300.
[0097] Shale sorbent 230 in the air preheat zone 314 may help to
capture mercury and mercury based pollutants in particulate matter
passed to the air preheat zone 314. Shale sorbent 230 may be
introduced into the air preheat zone 314 from a gasifier 200 or
other source. In addition, shale sorbent 230 introduced in earlier
process steps of the coal boiler system 300 may be passed into the
air preheat zone 314 where the shale sorbent 230 may react with
mercury-containing pollutants in the particulate matter found
therein. The reactions of shale sorbent 230 with mercury may
include reactions such as those shown by Reactions 5 through 8
herein.
[0098] In other embodiments of the invention, the shale sorbent 230
need not be fed to the coal boiler system 300 directly from the
gasifier 200 or other thermal conversion process. Instead, shale
sorbent 230 produced in a gasifier 200 or other thermal conversion
process according to embodiments of the invention may be stored for
later use and the stored shale sorbent 230 may be introduced to the
coal boiler system 300 at a desired time and in a desired manner.
For example, stored shale sorbent 230 from a storage facility may
be introduced into one or more shale sorbent inlets 230(a) in a
superheater zone 308 of a coal boiler system 300 and into one or
more shale sorbent inlets 230(b) in a reheat zone 310 of a coal
boiler system 300.
[0099] The introduction of shale sorbent 230 into a coal boiler
system 300 may reduce pollutants present in the products of the
coal boiler system 300, such as particulate matter and gases. The
shale sorbent 230 may adsorb or absorb some of the pollutants and
may react with others. For example, shale sorbent 230 comprising
calcium and magnesium may decrease pollutants according to
Reactions 47 and 48:
Ca/MgO+SO.sub.2+1/2O.sub.2.fwdarw.Ca/Mg-Sulfates (47),
Ca/MgO+2HCl.fwdarw.Ca/MgCl.sub.2+H.sub.2O (48).
[0100] The shale sorbent 230 may be introduced into a coal boiler
system 300 by entraining the shale sorbent 230 with air and
injecting the shale sorbent 230 into the coal boiler system 300 in
an air stream. The size of the shale sorbent 230 used may be
dependent upon the desired reactions and the pollutant control
desired for the type of coal 328 being combusted in the coal boiler
system 300. For example, in many coal boiler systems 300, the shale
sorbent 230 introduced into the coal boiler system 300 may have a
diameter of about 0.002 mm to about 0.015 mm. Shale sorbent 230
having a desired size may be produced in the gasifier 200 or other
thermal conversion process by introducing oil shale 210 having
sizes which result in the production of the desired shale sorbent
230 sizes into the gasifier 200 or other thermal conversion
process. In other embodiments, the shale sorbent 230 produced by
the gasifier 200 or other thermal conversion process may be ground
to a desired size prior to introduction of the shale sorbent 230
into the coal boiler system 300. For example, as illustrated in
FIG. 3, a grinder/classifier 290 may be incorporated with
embodiments of the invention to grind the shale sorbent 230
produced by the gasifier 200 into desired particle sizes.
Entrainment air 291 may also be introduced to the
grinder/classifier 290 to entrain the shale sorbent 230 for
delivery to the coal boiler system 300. In other embodiments of the
invention, pyrolysis gases 220 may be used to help fire the burners
in the burner zone 306 or may be burned to heat water and form
steam that is fed to the steam tubes 340. For example, some or all
of the pyrolysis gases 220 produced by the gasifier 200 or other
thermal conversion process during the gasification of oil shale 210
may be fed directly to the coal boiler system 300 as a source of
fuel for burners or for steam generation processes. The pyrolysis
gases 220 from the gasifier 200 or other thermal conversion process
may also be treated or otherwise processed to produce a desired
fuel composition in the pyrolysis gases 220 before such gases are
used as fuel for the coal boiler system 300.
[0101] According to still other embodiments of the invention, shale
sorbent 230 and pyrolysis gases 220 from a gasifier 200 or other
thermal conversion process may be introduced into a cement kiln or
other calcining process to help control pollutants formed in cement
kilns and cement production processes. For example, many cement
kiln processes do not meet the new pollution control requirements
being promulgated by the Environmental Protection Agency.
Incorporation of embodiments of the invention within such cement
kiln processes may effectively retrofit the cement kiln processes
such that the pyrolysis gases 220 and shale sorbent 230 may be used
to reduce pollutants from the cement kiln processes
[0102] A gasifier 200 or other thermal conversion process
incorporated with a cement kiln 400 according to particular
embodiments of the invention is illustrated in FIG. 4. The cement
kiln 400 may include any type of conventional cement kiln or kiln
designed for producing cement or cement clinker. As illustrated in
FIG. 4, the cement kiln 400 may include a dehydration zone 410, a
calcination zone 420, and a clinkering zone 430. Clay 402 for
producing cement clinker may be introduced into the dehydration
zone 410 at a solids input 404 according to conventional methods.
Moisture in the clay 402 is removed from the clay 402 in the
dehydration zone 410 of the cement kiln 400. The temperature in the
dehydration zone 410 may be controlled to achieve a desired amount
of dehydration based upon the moisture content of the clay 402
being fed to the cement kiln 400. For instance, the temperature in
the dehydration zone 410 may be set at between about 400.degree. C.
to about 500.degree. C.
[0103] Dehydrated clay 402 is transported from the dehydration zone
410 into the calcination zone 420 where the temperature may also be
controlled. The temperature in the calcination zone 420 may be
between, for example, about 500.degree. C. and about 1250.degree.
C. The clay 402 is calcined in the calcination zone 420 according
to conventional calcination techniques.
[0104] Calcined clay 402 may advance into the clinkering zone 430
where the final heating of the calcined clay 402 forms clinker 450
that may be used with cement. The temperature in the clinkering
zone 430 may be controlled between about 1250.degree. C. to about
1550.degree. C. The clinker 450 may exit the cement kiln 400 and
may be used according to conventional processes.
[0105] Heat may be provided to the cement kiln 400 according to
conventional processes, such as by use of gas/oil burners 440
located in or around the clinkering zone 430 of the cement kiln
400. The combustion of gas or oil in the gas/oil burners 440 may be
controlled such that the desired temperatures are achieved in the
clinkering zone 430, the calcination zone 420, and the dehydration
zone 410.
[0106] Effluent gases 460 generated in the cement kiln 400 may exit
the cement kiln and be fed to a process for cleaning the effluent
gases 460 of pollutants before being released into the environment
or biosphere. For example, as illustrated in FIG. 4, the effluent
gases 460 may exit the cement kiln 400 and be fed to a reactor 470
capable of scrubbing the effluent gases 460 or otherwise reducing
the amount of pollutants, if any, in the effluent gases.
[0107] According to embodiments of the invention, pyrolysis gases
220 from the gasifier 200 or other thermal conversion process may
be burned in the gas/oil burners 440 to provide heat to the cement
kiln 400. As illustrated in FIG. 4, a portion of the pyrolysis
gases 220 from the gasifier 200 or other thermal conversion process
may be fed to the gas/oil burners 440. The gasifier 200 or other
thermal conversion process may be operated such that pyrolysis
gases 220 produced within the gasifier 200 or other thermal
conversion process may be easily burned in the gas/oil burners 440
of the cement kiln 400. In this manner, additional sources of
heating gas for the gas/oil burners 440 may be provided by the
pyrolysis or gasification of oil shale 210 in a gasifier 200 or
other thermal conversion process according to embodiments of the
invention.
[0108] In other particular embodiments of the invention, at least a
portion of the pyrolysis gas 220 produced by the gasifier 200 or
other thermal conversion process may be fed to one or more zones of
the cement kiln 400 to help reduce pollutants in the various zones
of the cement kiln 400. Introduction of the pyrolysis gases 220
into the various zones of the cement kiln 400 may oxidize the
pyrolysis gases 220 and reduce pollutants contained in the gases
and solids within the cement kiln 400. For instance, pyrolysis
gases 220 introduced into various zones of the cement kiln 400 may
be oxidized in the presence of NO.sub.x in the cement kiln 400,
thereby reducing the nitrogen-containing pollutants to N.sub.2 or
other nitrogen-containing compounds, carbon dioxide ("CO.sub.2"),
and water ("H.sub.2O") in accordance with Reactions 3 and 4
previously described. Additional oxidization reactions, such as
those of Reactions 45 and 46, may also occur as a result of the
introduction of pyrolysis gas 220 or pyrolysis gas 220 products
into the various zones of a cement kiln 400. Such reactions may be
used to reduce the amount of pollutants in the cement kiln 400.
[0109] According to still other embodiments of the invention,
pyrolysis gases 220 may be fed to a cement kiln 400 from a storage
facility or other delivery process. For example, pyrolysis gases
220 produced by a gasifier 200 or other thermal conversion process
according to embodiments of the invention may be stored by
conventional methods before being used with a cement kiln 400 as
gas or fuel feed to a gas/oil burner 440 or as a pollutant control
gas in the various zones of the cement kiln 400. Pyrolysis gases
220 from a gasifier 200 or other thermal conversion process
according to embodiments of the invention may also undergo further
processing before being fed to a cement kiln 400 according to
embodiments of the invention. For instance, the pyrolysis gases 220
may be processed to form syngas or synfuels that may be used as a
fuel for the gas/oil burners 440 of a cement kiln 400.
[0110] The burning of pyrolysis gas 220 in a cement kiln 400 may
also reduce the burning of waste tires in a cement kiln 400 which
is conventionally done to increase the heat within a cement kiln
400 and to reduce NO.sub.x pollutants. The heat that may be
provided by pyrolysis gas 220 may replace the heat generated by the
burning of waste tires while still reducing NO.sub.x pollutants. In
addition, the removal of the burning of waste tires in the cement
kiln 400 may reduce the amounts of sulfur-containing pollutants and
mercury-containing pollutants in the cement kiln 400 which are
produced by the burning of waste tires.
[0111] In other particular embodiments of the invention, pollutants
formed or released in a cement kiln 400 may be reduced by the
introduction of shale sorbent 230 into the cement kiln 400. Shale
sorbent 230 may be introduced into a cement kiln 400 with the
introduction of clay 402 or at other locations in the cement kiln
400. As illustrated in FIG. 4, shale sorbent 230 from a gasifier
200 or other thermal conversion process may be combined with clay
402 and introduced in the cement kiln 400 or introduced with the
clay 402 into the cement kiln 400. Prior to introduction of the
shale sorbent 230 into the cement kiln 400, the shale sorbent 230
may be ground or otherwise processed to achieve a desired size for
the shale sorbent 230 entering the cement kiln 400. Shale sorbent
230 introduced into a cement kiln 400 may act as a reducing agent
for NO.sub.x pollutants found in the cement kiln 400 and
particularly in the upper end of the cement kiln 400 around the
dehydration zone 410 and calcination zone 420.
[0112] According to other embodiments, the shale sorbent 230
introduced into a cement kiln 400 clinkering process may entrain
pollutants produced in the process. For example, mercury-containing
pollutants formed during the clinkering process may be adsorbed or
absorbed by the shale sorbent 230 added to the clinkering process.
Mercury or mercuric chloride formed in the cement kiln 400 and
entrained in the cement retort being formed into cement clinker 450
may come into contact with shale sorbent 230 added to the
clinkering process. Contact between the shale sorbent 230 and the
mercury-containing compounds may result in the capture of the
mercury in the shale sorbent 230 in a manner similar to Reactions
7-10. In those instances where mercury or mercuric chloride
pollutant removal are desired, the shale sorbent 230 may be formed
in a gasifier 200 or other thermal conversion process such that the
amount of char or activated carbon in the shale sorbent 230 is
maximized for the reduction or capture of mercury-containing
compounds.
[0113] The introduction of shale sorbent 230 into a cement kiln 400
during a clinkering process may also reduce the amount of other
pollutants found in the cement retort or cement clinker 450 of the
cement kiln 400 according to embodiments of the invention. The
shale sorbents 230 produced by a gasifier 200 may be tailored such
that the amount of char or activated carbon in the shale sorbents
230 is at a desired level for the particular clinkering process to
which the shale sorbent 230 is being added. In addition, the size
of the shale sorbent 230 particles added to a cement kiln 400 may
be tailored to the desired reactions in the cement kiln 400. For
example, shale sorbent 230 from a gasifier 200 or other thermal
conversion process or from a storage facility may be ground or
otherwise processed to produce shale sorbent 230 having a desired
particle size for a particular clinkering process.
[0114] The introduction of shale sorbent 230 into the cement kiln
400 may also provide an additional source of material for forming
cement clinker 450. The use of oil shale as a cement clinker 450
production component has been conventionally used. As with the
clinkering of oil shale, the clinkering of shale sorbent 230 may
provide a cement clinker 450 that is desirable. The size of the
shale sorbent 230 used to produce cement clinker 450 may be
controlled, such as by feeding the shale sorbent 230 formed in
gasifier 200 to a grinder/classifier 290 prior to introduction of
the shale sorbent 230 into a cement kiln 400 as illustrated in FIG.
4.
[0115] In still other particular embodiments of the invention, the
shale sorbent 230 produced in a gasifier 200 or other thermal
conversion process may be used to scrub or otherwise remove
pollutants from effluent gases 460 from a cement kiln 400. For
example, as illustrated in FIG. 4, shale sorbent 230 produced by
gasifier 200 or other thermal conversion process may be fed to a
reactor 470 where effluent gases 460 from a cement kiln 400 may be
cleaned of pollutants. The reactor 470 may include a fixed or
transport reactor sorbent bed wherein shale sorbent 230 is used to
remove pollutants such as mercury-containing pollutants,
sulfur-containing pollutants, nitrogen-containing pollutants, and
hydrochloric acid.
[0116] As illustrated in FIG. 4, effluent gases 460 from a cement
kiln 400 may be fed to the reactor 470 along with shale sorbent 230
from a gasifier 200 or other thermal conversion process or other
source. Pollutants in the effluent gases 460 may react with the
shale sorbent 230 according to Reactions described herein. For
example, sulfur-containing pollutants may react with the shale
sorbent 230 in accordance with Reactions 9-15; mercury-containing
pollutants may react with the shale sorbent 230 in accordance with
Reactions 7-10; and hydrochloric acid ("HCl") may react with shale
sorbent 230 in accordance with Reactions 22-23.
[0117] Spent shale sorbent 230 which may have absorbed or adsorbed
its limits of pollutants maybe removed from the reactor 470 and
stored or otherwise disposed of according to conventional
methods.
[0118] Although embodiments of the invention have been described
with respect to the use of a shale sorbent 230 and pyrolysis gas
220 from a gasifier 200 or other thermal conversion process as
illustrated in FIG. 4, it is also understood that the shale sorbent
230 or pyrolysis gas 220 used with the cement kiln 400 may be
obtained from other sources. For example, pyrolysis gas 220 from a
gasifier 200 or other thermal conversion process may be stored or
otherwise processed offsite and delivered to a cement kiln 400 such
as by pipeline or tanker truck. Similarly, shale sorbent 230
produced by a gasifier 200 or other thermal conversion process may
be stored and later transported to a cement kiln 400 for use with a
clinkering process or as a pollutant control for scrubbing effluent
gases 460.
[0119] Shale sorbent 230 added to a cement kiln 400 may also
contribute energy to produce heat (or enthalpy) to the cement kiln
400 system. For example, the addition of shale sorbent 230 to a
cement kiln 400 may contribute some enthalpy to the cement kiln 400
in a manner similar to the addition of oil shale to increase
enthalpy of a system in accordance with Reactions 24-31.
[0120] According to still other embodiments of the invention, the
shale sorbent 230 and pyrolysis gas 220 products of a gasifier 200
or other thermal conversion process may be used in the production
of synthesis gas, or syngas, and synthesis fuels, or synfuels. As
illustrated in FIG. 5, a gasifier 200 or other thermal conversion
process according to embodiments of the invention may be combined
with a syngas or synfuels production process 500.
[0121] In a syngas production process, a feedstock 560 such as
coal, municipal waste, waste tires, biomass, or other synthesis gas
feedstock, may be fed to a syngas gasifier 550 where the feedstock
560 is burned to form carbon monoxide ("CO") and hydrogen
("H.sub.2"), or a syngas 565. The carbon monoxide and hydrogen may
then be used in a syngas or synfuels production process. Steam 512
and oxidizer air 514 may be fed to the syngas gasifier 550 to
promote the combustion of the feedstock 560 in the syngas gasifier
550. Waste products 568 from the syngas gasifier 550 may include
pollutants such as mercury-containing pollutants and other metal
pollutants.
[0122] According to particular embodiments of the invention, the
pyrolysis gases 220 from the gasifier 200 or other thermal
conversion process may be combined with the syngas 565 in a reactor
570, such as a fixed or fluid-bed reactor. The combination of the
pyrolysis gases 220 with the syngas 565 may form a product gas 572
which may be used in the further processing of syngas and synfuels.
For example, the product gas 572 may include components such as
carbon monoxide, carbon dioxide, hydrogen, light hydrocarbons, and
heavy hydrocarbons. The product gas 572 may be processed according
to conventional methods to form syngas and synfuels.
[0123] Shale sorbent 230 from the gasifier 200 or other thermal
conversion process may also be fed to the reactor 570. The shale
sorbent 230 in the reactor 570 may be used to absorb or adsorb
pollutants from the pyrolysis gas 220 and syngas 565 which is
combined in the reactor 570.
[0124] Shale sorbent 230 from the gasifier 200 or other thermal
conversion process may also be fed to a transport reactor 580, such
as a fixed or fluidized-bed reactor. Waste products 568 from the
syngas gasifier 550 may also be fed to the transport reactor 580.
The combination of the waste products 568 with the shale sorbent
230 in the transport reactor 580 may allow the shale sorbent 230 to
absorb or adsorb pollutants from the waste products 568. For
example, the shale sorbent 230 fed to the transport reactor 580 may
adsorb or absorb pollutants such as sulfur-containing pollutants,
halide compounds, mercury-containing pollutants, or other
pollutants from the waste products 568. The spent shale sorbent 231
may be reclaimed for construction material or may be discarded in
landfills according to conventional processes. In some instances,
the pozzolanic nature of the spent shale 231 will help immobilize
the pollutants and contaminants absorbed or adsorbed by the shale
sorbent 230 when stored in a landfill.
[0125] Although the transport reactor 580 illustrated in FIG. 5 is
a single reactor, a series of transport reactors may be used. In
some instances, the temperatures of a series of transport reactors
may be controlled such that different pollutants are adsorbed or
absorbed by the shale sorbent 230 fed to each of the transport
reactors.
[0126] According to still other embodiments of the invention, shale
sorbent 230 and pyrolysis gases 220 from a gasifier 200 or other
thermal conversion process may be used in metallurgical processes.
For example, in a metallurgical process such as an ore smelting or
refining process, large amounts of energy are used to provide heat
to the process. The process also creates pollutants which must be
captured or otherwise reduced from the waste products before being
disposed of. The combination of a gasifier 200 or other thermal
conversion process according to embodiments of the invention with a
metallurgical process may provide a heating gas, a pollutant
reduction gas, and a sorbent for adsorbing or absorbing pollutants
from the waste products produced by the process.
[0127] In a metallurgical process, pyrolysis gases 220 from a
gasifier 200 or other thermal conversion process may be used as
heating gasses or fuel to help provide the heat that is necessary
for the metallurgical process. The pyrolysis gases 220 may also be
burned or subject to oxidation to reduce pollutants such as
NO.sub.x pollutants in the process. The shale sorbent 230 created
by the gasifier 200 may be combined with the process or with the
waste products from the process to remove pollutants from the waste
products. For example, the shale sorbent 230 may be used to remove
sulfur-containing pollutants, mercury-containing pollutants, halide
compounds, metal pollutants, or other pollutants from the waste
products.
[0128] Embodiments of the invention, therefore, may be used or
combined with many different processes to provide additional
heating gases, pollutant reduction gases, or pollution sorbents for
the processes. Although embodiments of the invention have been
described with respect to particular processes, it is understood
that the embodiments of the invention, and the pyrolysis gases 220
and shale sorbents 230 of the invention, may be combined with other
process and particularly other processes where additional heating
supplies are desired or where additional pollutant control
mechanisms are desired.
[0129] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and have been described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Rather, the invention is to cover all modifications, equivalents,
and alternatives falling within the spirit and scope of the
invention as defined by the following appended claims.
* * * * *