U.S. patent application number 14/243395 was filed with the patent office on 2014-08-21 for oxy-fuel combustion with integrated pollution control.
The applicant listed for this patent is JUPITER OXYGEN CORPORATION. Invention is credited to Thomas L. Ochs, Danylo B. Oryshchyn, Brian R. Patrick, Cathy A. Summers, Paul C. Turner.
Application Number | 20140230703 14/243395 |
Document ID | / |
Family ID | 38228936 |
Filed Date | 2014-08-21 |
United States Patent
Application |
20140230703 |
Kind Code |
A1 |
Patrick; Brian R. ; et
al. |
August 21, 2014 |
OXY-FUEL COMBUSTION WITH INTEGRATED POLLUTION CONTROL
Abstract
An oxygen fueled integrated pollutant removal and combustion
system includes a combustion system and an integrated pollutant
removal system. The combustion system includes a furnace having at
least one burner that is configured to substantially prevent the
introduction of air. An oxygen supply supplies oxygen at a
predetermine purity greater than 21 percent and a carbon based fuel
supply supplies a carbon based fuel. Oxygen and fuel are fed into
the furnace in controlled proportion to each other and combustion
is controlled to produce a flame temperature in excess of 3000
degrees F. and a flue gas stream containing CO2 and other gases.
The flue gas stream is substantially void of non-fuel borne
nitrogen containing combustion produced gaseous compounds. The
integrated pollutant removal system includes at least one direct
contact heat exchanger for bringing the flue gas into intimated
contact with a cooling liquid to produce a pollutant-laden liquid
stream and a stripped flue gas stream and at least one compressor
for receiving and compressing the stripped flue gas stream.
Inventors: |
Patrick; Brian R.; (Chicago,
IL) ; Ochs; Thomas L.; (Albany, OR) ; Summers;
Cathy A.; (Albany, OR) ; Oryshchyn; Danylo B.;
(Philomath, OR) ; Turner; Paul C.; (Independence,
OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
JUPITER OXYGEN CORPORATION |
Schiller Park |
IL |
US |
|
|
Family ID: |
38228936 |
Appl. No.: |
14/243395 |
Filed: |
April 2, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13340198 |
Dec 29, 2011 |
8714968 |
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14243395 |
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11306437 |
Dec 28, 2005 |
8087926 |
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13340198 |
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Current U.S.
Class: |
110/345 ;
110/203; 110/204; 110/263; 110/297 |
Current CPC
Class: |
Y02E 20/322 20130101;
Y02E 20/363 20130101; Y02E 20/344 20130101; F23J 2900/15061
20130101; F23J 15/06 20130101; F23L 7/007 20130101; F23C 9/00
20130101; F23J 15/006 20130101; Y02E 20/34 20130101; F23L
2900/07001 20130101; Y02E 20/326 20130101; F23D 1/005 20130101;
Y02E 20/32 20130101; B01D 53/002 20130101; Y02E 20/30 20130101;
B01D 2257/504 20130101 |
Class at
Publication: |
110/345 ;
110/203; 110/297; 110/263; 110/204 |
International
Class: |
F23L 7/00 20060101
F23L007/00; B01D 53/00 20060101 B01D053/00; F23J 15/06 20060101
F23J015/06; F23C 9/00 20060101 F23C009/00; F23D 1/00 20060101
F23D001/00 |
Claims
1. An oxygen fueled integrated pollutant removal and combustion
system comprising: a combustion system including a furnace having
at least one burner, and configured to substantially prevent the
introduction of air, an oxygen supply for supplying oxygen at a
predetermine purity greater than 21 percent, a carbon based fuel
supply for supplying a carbon based fuel, means for feeding the
oxygen and the carbon based fuel into the furnace in controlled
proportion to each other, means for controlling the combustion of
the carbon based fuel to produce a flame temperature in excess of
3000 degrees F. and a flue gas stream containing CO2 and other
gases and substantially void of non-fuel borne nitrogen containing
combustion produced gaseous compounds; and a pollutant removal
system including at least one direct contact heat exchanger for
bringing the flue gas into intimated contact with a cooling liquid
to produce a pollutant-laden liquid stream and a stripped flue gas
stream and at least one compressor for receiving and compressing
the stripped flue gas stream.
2. The integrated combustion system in accordance with claim 1
wherein the cooling liquid is water.
3. The integrated combustion system in accordance with claim 1
including at least two compressors.
4. The integrated combustion system in accordance with claim 1
wherein the stripped flue gas stream is separated into
non-condensable gases and condensable gases.
5. The integrated combustion system in accordance with claim 4
wherein the condensable gases are condensed into a substantially
liquid state.
6. The integrated combustion system in accordance with claim 5
wherein the gases condensed into the substantially liquid state are
sequestered.
7. The integrated combustion system in accordance with claim 6
wherein the gases condensed into the substantially liquid state
are, in large part, CO2.
8. The integrated combustion system in accordance with claim 1
wherein the carbon based fuel is a solid fuel and wherein the
stripped flue gas stream is recirculated, in part, to carry the
carbon based fuel into the furnace.
9. The integrated combustion system in accordance with claim 8
wherein the stripped flue gas stream is substantially CO2.
10. The integrated combustion system in accordance with claim 1
including a plurality of heat exchangers and compressors, wherein
at least two of the heat exchangers are direct contact heat
exchangers for intimately contacting cooling water with the flue
gas stream and wherein at least one compressor is disposed between
the heat exchangers for compressing the stripped flue gas stream
between the heat exchangers.
11. An oxygen fueled combustion system comprising: a combustion
system having a furnace having a controlled environment with
substantially no in-leakage from an external environment, and
configured to substantially prevent the introduction of air, an
oxidizing agent supply for supplying oxygen having a predetermined
purity and a carbon based fuel supply for supplying a carbon based
fuel and including means for feeding the oxygen and the carbon
based fuel into the furnace in a stoichiometric proportion to one
another limited to an excess of either the oxygen or the carbon
based fuel to less than 5 percent over the stoichiometric
proportion, and means for controlling the combustion of the carbon
based fuel to produce an flue gas stream from the furnace having
substantially zero nitrogen-containing combustion produced gaseous
compounds from the oxidizing agent; and a pollutant removal system
including at least one direct contact heat exchanger for bringing
the flue gas stream into intimated contact with a cooling water to
produce a pollutant-laden liquid stream and a stripped flue gas
stream and at least one compressor for receiving and compressing
the stripped flue gas stream.
12. The integrated combustion system in accordance with claim 11
including at least two heat exchangers and at least two
compressors.
13. The integrated combustion system in accordance with claim 11
wherein the stripped flue gas stream is separated into
non-condensable gases and condensable gases.
14. The integrated combustion system in accordance with claim 13
wherein the condensable gases are condensed into a substantially
liquid state.
15. The integrated combustion system in accordance with claim 14
wherein the gases condensed into the substantially liquid state are
sequestered.
16. The integrated combustion system in accordance with claim 15
wherein the gases condensed into the substantially liquid state
are, in large part, CO2.
17. The integrated combustion system in accordance with claim 1
wherein the carbon based fuel is a solid fuel and wherein the
stripped flue gas stream is recirculated, in part, to carry the
carbon based fuel into the furnace.
18. The integrated combustion system in accordance with claim 17
wherein the carbon based fuel is coal and/or a mixture of coal and
another solid fuel.
19. The integrated combustion system in accordance with claim 18
wherein the stripped flue gas stream is substantially CO2.
20. The integrated combustion system in accordance with claim 11
including a plurality of heat exchangers and compressors, wherein
at least two of the heat exchangers are direct contact heat
exchangers for intimately contacting cooling water with the flue
gas stream and wherein at least one compressor is disposed between
heat exchangers for compressing the stripped flue gas stream
between the heat exchangers.
21. A combustion and integrated pollutant removal method comprising
the steps of: providing a furnace having at least one burner, and
configured to substantially prevent the introduction of air;
providing an oxygen supply for supplying oxygen at a predetermine
purity greater than 21 percent; providing a carbon based fuel
supply for supplying a carbon based fuel limiting an excess of
either the oxygen or the carbon based fuel to less than 5 percent
over the stoichiometric proportion; controlling the combustion of
the carbon based fuel to produce a flame temperature in excess of
3000 degrees F. and a flue gas stream containing CO2 and other
gases and substantially void of non-fuel borne nitrogen containing
combustion produced gaseous compounds; providing a pollutant
removal system including a direct contact heat exchanger in serial
arrangement with a compressor; bringing the flue gas into intimated
contact with a cooling liquid in the heat exchanger to produce a
pollutant-laden liquid stream and a stripped flue gas stream
feeding the stripper flue gas stream into the compressor to
compress the stripped flue gas stream.
22. The method in accordance with claim 21 including the steps of
cooling the stripped flue gas stream compressing the cooled
stripped flue gas stream.
23. The method in accordance with claim 22 including the step of
sequestering the compressed cooled stripped flue gas stream.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention pertains to an integrated oxygen
fueled combustion and pollution control system. More particularly,
the present invention pertains to an oxy-fueled combustion system
having integrated pollution control to effectively reduce, to near
zero, emissions from combustion sources.
[0002] Oxy-fueled combustion systems are known in the art. Such
systems use essentially pure oxygen for combustion with fuel in
near stoichiometric proportions and at high flame temperatures for
high efficiency energy production. Oxy-fuel systems are used in
boilers to produce steam for electrical generation and in
industrial settings, such as in aluminum recycling to melt aluminum
for recasting. It is also contemplated that oxy-fueled combustion
can be used for waste incineration as well as other industrial and
environmental applications. Oxy-fuel technology and uses for this
technology are disclosed in Gross, U.S. Pat. Nos. 6,436,337,
6,596,220, 6,797,228 and 6,818,176, all of which are commonly owned
with the present application and are incorporated herein by
reference.
[0003] Advantageously, because oxy-fuel combustion uses oxygen
rather than air as an oxygen source, there is concomitant reduction
in flue gas produced. In addition, combustion is carried out so
that the NOx combustion products are near zero and are due almost
exclusively to fuel-borne nitrogen. That is, because oxygen rather
than air is used as an oxygen source, there is less mass flow and
no nitrogen to contribute to the formation of NOx.
[0004] Although oxy-fuel combustion provides fuel efficiency and
reduced emission energy generation, there is still a fairly
substantial amount of emissions that are produced during the
combustion process. In addition, because the volume of gas is less,
due to the use of oxygen instead of air, the concentration of other
pollutants is higher. For example, the mass of SOx and particulate
matter will not change, however, the concentration will increase
because of the reduced overall volume.
[0005] Pollution control or removal systems are known in the art.
These systems can, for example, use intimate contact between the
flue gases and downstream process equipment such as precipitators
and scrubbers to remove particulate matter, sulfur containing
compounds and mercury containing compounds. Other systems use
serial compression stripping of pollutants to remove pollutants and
recover energy from the flue gas stream. Such a system is disclosed
in Ochs, U.S. Pat. No. 6,898,936, incorporated herein by
reference.
[0006] Accordingly, there is a need for a combustion system that
produces low flue gas volume with integrated pollution removal.
Desirably, such a system takes advantage of known combustion and
pollution control systems to provide fuel efficient energy
production in conjunction with reduced pollutant production and
capture of the remaining pollutants that are produced.
BRIEF SUMMARY OF THE INVENTION
[0007] An integrated oxygen fueled combustion system and pollutant
removal system, reduces flue gas volumes, eliminates NOx and
capture condensable gases. The system includes a combustion system
having a furnace with at least one burner that is configured to
substantially prevent the introduction of air. An oxygen supply
supplies oxygen at a predetermine purity greater than 21 percent
and a carbon based fuel supply supplies a carbon based fuel. Oxygen
and fuel are fed into the furnace in controlled proportion to each
other. Combustion is controlled to produce a flame temperature in
excess of 3000 degrees F. and a flue gas stream containing CO2 and
other gases and is substantially void of non-fuel borne nitrogen
containing combustion produced gaseous compounds.
[0008] The pollutant removal system includes at least one direct
contact heat exchanger for bringing the flue gas into intimated
contact with a cooling liquid, preferably water, to produce a
pollutant-laden liquid stream and a stripped flue gas stream. The
system includes at least one compressor for receiving and
compressing the stripped flue gas stream.
[0009] Preferably, the system includes a series of heat exchangers
and compressors to cool and compress the flue gas. The flue gas can
be cooled and compressed to and the stripped flue gas stream can
separated into non-condensable gases and condensable gases. The
condensable gases, in large part CO2, are condensed into a
substantially liquid state and can be sequestered. The CO2 can be
recirculated, in part, to carry a solid fuel such as coal into the
furnace.
[0010] A method oxy-fuel combustion integrated with pollutant
removal includes providing a furnace having at least one burner,
and configured to substantially prevent the introduction of air,
providing an oxygen supply for supplying oxygen at a predetermine
purity greater than 21 percent and providing a carbon based fuel
supply for supplying a carbon based fuel.
[0011] Either or both of the oxygen and carbon based fuel are
limited to less than 5 percent over the stoichiometric proportion
and combustion is controlled to produce a flame temperature in
excess of 3000 degrees F. and a flue gas stream containing CO2 and
other gases and substantially void of non-fuel borne nitrogen
containing combustion produced gaseous compounds.
[0012] The pollutant removal system is provided which includes a
direct contact heat exchanger in serial arrangement with a
compressor. The flue gas is brought into intimated contact with a
cooling liquid, preferably water, in the heat exchanger to produce
a pollutant-laden liquid stream and a stripped flue gas stream. The
stripped flue gas stream is fed into the compressor to compress the
stripped flue gas stream.
[0013] In a preferred method, the steps of cooling the stripped
flue gas stream and compressing the cooled stripped flue gas stream
are carried out as well as sequestering the compressed cooled
stripped flue gas stream.
[0014] These and other features and advantages of the present
invention will be apparent from the following detailed description,
in conjunction with the appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0015] The benefits and advantages of the present invention will
become more readily apparent to those of ordinary skill in the
relevant art after reviewing the following detailed description and
accompanying drawings, wherein:
[0016] FIG. 1 is flow diagram of an integrated oxy-fuel combustion
and pollutant removal system that was assembled for testing the
principles of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] While the present invention is susceptible of embodiment in
various forms, there is shown in the drawings and will hereinafter
be described a presently preferred embodiment with the
understanding that the present disclosure is to be considered an
exemplification of the invention and is not intended to limit the
invention to the specific embodiment illustrated. It should be
further understood that the title of this section of this
specification, namely, "Detailed Description Of The Invention",
relates to a requirement of the United States Patent Office, and
does not imply, nor should be inferred to limit the subject matter
disclosed herein.
[0018] As discussed in the aforementioned patents to Gross, an
oxy-fuel combustion system uses essentially pure oxygen, in
combination with a fuel source to produce heat, by flame production
(i.e., combustion), in an efficient, environmentally non-adverse
manner. Oxygen, which is supplied by an oxidizing agent, in
concentrations of about 85 percent to about 99+ percent can be
used, however, it is preferable to have oxygen concentration (i.e.,
oxygen supply purity) as high as possible.
[0019] In such a system, high-purity oxygen is fed, along with the
fuel source in stoichiometric proportions, into a burner in a
furnace. The oxygen and fuel is ignited to release the energy
stored in the fuel. For purposes of the present disclosure,
reference to furnace is to be broadly interpreted to include any
industrial or commercial heat generator that combusts fossil
(carbon-based) fuel. For example, water-tube-walled boilers for
electrical power generation, as well as direct fired furnaces for
industrial applications are contemplated to use the oxy-fueled
combustion system. In a preferred system, oxygen concentration or
purity is as high as practicable to reduce green-house gas
production.
[0020] It is contemplated that essentially any fuel source can be
used. For example, oxygen can be fed along with natural gas, for
combustion in a furnace. Other fuel sources contemplated include
oils including refined as well as waste oils, wood, coal, coal
dust, refuse (garbage waste), animal wastes and products and the
like. Those skilled in the art will recognize the myriad fuel
sources that can be used with the present oxy-fuel system.
[0021] Compared to conventional combustion processes which use air
as an oxidizing agent to supply oxygen, rather than essentially
pure oxygen, for combustion, the oxy-fuel system has an overall
flow throughput that is greatly reduced. The oxygen component of
air (about 21 percent) is used in combustion, while the remaining
components (essentially nitrogen) are heated in and exhausted from
the furnace. Moreover, the present process uses oxygen in a
stoichiometric proportion to the fuel. That is, only enough oxygen
is fed in proportion to the fuel to assure complete combustion of
the fuel. Thus, no "excess" oxygen is fed into the combustion
system.
[0022] Many advantages and benefits are achieved using the oxy-fuel
combustion system. Aside from increased efficiency (or conversely
reduced fuel consumption to produce an equivalent amount of power),
because of the reduced input of gas, there is a dramatic decrease
in the volume of flue gas. Based on the difference between using
air which is 21 percent oxygen and pure oxygen, the volumetric flow
rate is about one-fifth (1/5) using an oxy-fuel combustion system,
compared to a conventional air-fed combustion system. In addition,
because there is no energy absorbed by non-combustion related
materials (e.g., excess oxygen or nitrogen), more energy is
available for the underlying process.
[0023] Advantageously, the reduced gas volume (and thus flue gas
volume) also increases the residence time of the gases in the
furnace or boiler to provide additional opportunity for heat
transfer.
[0024] In that the overall flue gas volume is so greatly reduced,
highly efficient downstream processing that would otherwise not be
available or would be impractical can now be used in large scale
industrial and power generation settings.
[0025] Accordingly, the present invention uses oxy-fuel combustion
in conjunction with the removal of multiple pollutants through the
integrated condensation of H2O and CO2 with entrainment of
particulates and dissolution and condensation of other pollutants
including SO2. Such a pollutant removal system and method is
disclosed in the aforementioned patent to Ochs et al.
[0026] Consolidating the removal of pollutants into one process has
the potential to reduce costs and reduce power requirements for
operation of such a system. Non-condensable combustion products
including oxygen and argon may be present in combustion products.
Although the oxy-fuel combustion system is operated at or very near
stoichiometry (preferably within 5 percent of stoichiometry),
oxygen may be present in the flue gas. Argon can come from the air
separation process (remaining in the produced oxygen). Some
relatively small amounts of nitrogen may also be present as
fuel-borne or as air in-leakage into the underlying process
equipment.
[0027] Condensable vapors such as H2O, CO2, SOx, and although
minimal, NOx, are produced in the combustion process and are the
targets for condensation. When referring to combustion products in
this invention it is assumed that these condensable vapors and
non-condensable gases are present as well as particulates and other
pollutants.
[0028] The pollutant control portion of the system can also
accomplish remediation and recovery of energy from combustion
products from a fossil fuel power plant having a fossil fuel
combustion chamber (e.g., a boiler, furnace, combustion turbine or
the like), a compressor, a turbine, a heat exchanger, and a source
of oxygen (which could be an air separation unit). Those skilled in
the art will understand and appreciate that reference to, for
example, a compressor, includes more than one compressor.
[0029] The fossil fuel power plant combustion products can include
non-condensable gases such as oxygen and argon; condensable vapors
such as water vapor and acid gases such as SOX and (again, although
minimal, NOX); and CO2 and pollutants such as particulates and
mercury. The process of pollutant removal and sequestration,
includes changing the temperature and/or pressure of the combustion
products by cooling and/or compressing the combustion products to a
temperature/pressure combination below the dew point of some or all
of the condensable vapors.
[0030] This process is can out to condense liquid having some acid
gases dissolved and/or entrained therein and/or directly condensing
the acid gases (such as CO2 and SO2) from the combustion products.
It is carried out further to dissolve some of the pollutants thus
recovering the combustion products. Dissolve in the context of this
disclosure means to entrain and/or dissolve.
[0031] This process is repeated through one or more of cooling
and/or compressing steps with condensation and separation of
condensable vapors and acid gases. The recovery of heat in the form
of either latent and/or sensible heat cab also be accomplished. The
condensation reduces the energy required for continued compression
by reducing mass and temperature, until the partially remediated
flue gas is CO2, SO2, and H2O poor. Thereafter the remaining flue
gases are sent to an exhaust.
[0032] The fossil fuel can be any of those discussed above. In
certain instances, the pollutants will include fine particulate
matter and/or heavy metals such as mercury other metals such as
vanadium.
[0033] The present invention also relates to a method of applying
energy saving techniques, during flue gas recirculation and
pollutant removal, such that power generation systems can improve
substantially in efficiency. For example, in the case of a
subcritical pulverized coal (PC) system without energy recovery,
the performance can drop from 38.3% thermal efficiency (for a
modern system without CO2 removal) to as low as 20.0% (for the
system with CO2 removal and no energy recovery). A system according
to one embodiment of the present invention can perform at 29.6%
(with CO2 removal) when energy recovery is included in the model
design. it is anticipated that better efficiencies will be
achieved. The present oxy-fuel combustion with integrated pollution
control is applicable to new construction, repowering, and
retrofits.
[0034] In an exemplary system using the present oxy-fuel and IPR
process, flue gases as described in the table below are predicted.
The flue gases will exit from the combustion region or furnace
area, where they would pass through a cyclone, bag house or
electrostatic precipitator for gross particulate removal. The
combustion gas then passes through a direct contact heat exchanger
(DCHX). In this unit the flue gases come into contact with a cooler
liquid. This cooling step allows the vapors to condense. The step
also allows for dissolving the entrained soluble pollutants and
fine particles.
[0035] The gases exiting the first column are now cleaner and
substantially pollutant free. These gases are compressed and can
proceed into a successive DCHX and compression step. A final
compression and heat exchange step is used to separate the oxygen,
argon, and nitrogen (minimal) from the CO2. Also a mercury trap is
used to remove gaseous mercury before release to atmosphere.
[0036] The table below shows the expected results as a comparison
of the present oxy-fuel combustion and IPR system to a conventional
air fueled combustion process. As the results show, the volume of
flue gas at the outset, is less in the oxy-fuel combustion system
by virtue of the elimination of nitrogen from the input stream. In
the present system, the IPR serves to further reduce the volume and
gas flow through successive compression and cooling stages. As the
flue gases progress through the combined processes the final
product is captured CO2 for sequestration.
TABLE-US-00001 TABLE 1 A COMPARISON OF THE PROPERTIES AND
COMPOSITIONS OF IPR-TREATED OXY-FUEL COMBUSTION PRODUCTS WITH THOSE
FROM A CONVENTIONAL COAL FIRED BOILER Conventional after Oxyfuel
After 1.sup.st After 2.sup.nd After 3rd economizer exhaust
compression compression compression Gas Flow (kg/hr) 1,716,395
686,985 364,367 354,854 353,630 Vol flow (m.sup.3/hr) 1,932,442
826,995 72,623 15,944 661 Inlet Pressure 14.62 15.51 62 264 1,500
(psia) Inlet Temp. (.degree.F.) 270 800 342 323 88.2 Density
(kg/m.sup.3) 0.8882 0.8307 5.02 22.26 534.61 H.sub.2O (fraction)
0.0832 0.33222 0.0695 0.00994 0.0004 Ar (fraction) 0.0088 0.01152
0.0163 0.01730 0.0175 CO.sub.2 (fraction) 0.1368 0.61309 0.8662
0.92161 0.9305 N.sub.2 (fraction) 0.7342 0.00904 0.0128 0.01359
0.0137 O.sub.2 (fraction) 0.0350 0.02499 0.0353 0.03755 0.0379
SO.sub.2 (fraction) 0.0020 0.00913 0.0000 0.00000 0.0000
[0037] As can be seen from the data of Table 1, the volume of the
combustion products has dropped significantly as a result of the
successive compressing and cooling stages. The result is a capture
of CO2 and subsequent sequestration, which is the ultimate goal.
The CO2 thus resulting can be stored or used in, for example, a
commercial or industrial application.
[0038] A test system 10 was constructed to determine the actual
results vis-a-vis oxy-fuel combustion in conjunction with CO2
sequestration and pollutant removal. A schematic of the test system
is illustrated in FIG. 1. The system 10 includes an oxy-fueled
combustor 12 having a coal feed 14 (with CO2 as the carrier gas
16), and an oxygen feed 18. Coal was fed at a rate of 27 lbs per
hour (pph), carried by CO2 at a rate of 40 pph, and oxygen at a
rate of 52 pph. In that the system 10 was a test system rather than
a commercial or industrial system (for example, a commercial boiler
for electrical generation), the combustor 12 was cooled with
cooling water to serve as an energy/heat sink.
[0039] The combustor exhaust 20 flowed to a cyclone/bag house 22 at
which ash (as at 24) was removed at a rate of about 1 pph.
Following ash removal 24, about 118 pph of combustion gases
remained in the flue gas stream 26 at an exit temperature that was
less than about 300.degree. F.
[0040] The remaining flue gases 26 were then fed to a direct
contact heat exchanger 28 (the first heat exchanger). Water
(indicated at 30) was sprayed directly into the hot flue gas stream
26. The cooling water condensed some of the hot water vapor and
further removed the soluble pollutants and entrained particulate
matter (see discharge at 32). About 13 pph of water vapor was
condensed in the first heat exchanger 28--the flue gases that
remained 34 were present at a rate of about 105 pph.
[0041] Following exit from the first heat exchanger 28, the
remaining gases 34 were fed into a first, a low pressure compressor
36, (at an inlet pressure of about atmospheric) and exited the
compressor 36 at a pressure of about 175 lbs per square inch gauge
(psig). As a result of the compression stage, the temperature of
the gases 38 increased. The remaining flue gases were then fed into
a second direct contact heat exchanger 40 where they were brought
into intimate contact with a cooling water stream as at 42. The
exiting stream 44 released about an additional 4 pph of water and
thus had an exiting exhaust/flue gas 44 flow rate of about 101
pph.
[0042] Following the second heat exchanger 40, the gases 44 were
further compressed to about 250 psig at a second compressor 46.
Although the second compression stage resulted in a temperature
increase, it was determined during testing that a third heat
exchange step was not necessary. It will be appreciated that in
larger scale operation, however, such additional heat
exchange/cooling stages may be necessary.
[0043] A third compression stage, at a third compressor 48 was then
carried out on the remaining flue gases 50 to increase the pressure
of the exiting gas stream 52 to about 680 psig. Again, it was
determined that although the temperature of the gases increased,
active or direct cooling was not necessary in that losses to
ambient through the piping system carrying the gases were
sufficient to reduce the temperature of the gases.
[0044] A final compression, at a final compressor 52, of the gases
was carried out to increase the pressure of the gases to about 2000
psig. Following the final compression stage, the remaining gases 56
were fed into a heat exchanger 58, the final heat exchanger, in
which the temperature of the stream 56 was reduced to below the dew
point of the of the gases and as a result, condensation of the
gases commenced. The condensate (as at 60), which was principally
liquefied CO2 (at a rate of 80 pph), was extracted and sequestered.
In the present case, the CO2 was bottled, and retained.
[0045] The non-condensable gases (as at 62), which included a small
amount of CO2, were passed through a mercury filter 64 and
subsequently bled into an accumulator 66. The accumulator 66
provided flexibility in control of the system flow rate. The
exhaust 68 from the accumulator 66 was discharged to the
atmosphere. The flow rate from the accumulator 66, normalized to
steady state from the overall system, was about 21 pph.
[0046] It will be appreciated by those skilled in the art that the
above-presented exemplary system 10 was for testing and
verification purposes and that the number and position of the
compression and cooling stages can and likely will be changed to
accommodate a particular desired design and/or result. In addition,
various chemical injection points 70, filters 72, bypasses 74 and
the like may also be incorporated into the system 10 and,
accordingly, all such changes are within the scope and spirit of
the present invention.
[0047] The projected fuel savings and other increased efficiencies
of the present oxy-fuel combustion system with IPR are such that
the cost of this combined process is anticipated to be competitive
with current combustion technologies. Additionally, the prospect of
new regulatory requirements are causing power plant designers to
revisit the conventional approaches used to remove pollutants which
would only serve to improve the economics behind this approach.
[0048] It will be appreciated that the use of oxy-fueled combustion
systems with IPR in many industrial and power generating
applications can provide reduced fuel consumption with equivalent
power output or heat generation. Reduced fuel consumption, along
with efficient use of the fuel (i.e., efficient combustion) and
integrated R provides significant reductions in overall operating
costs, and reduced and sequestered emissions of other exhaust/flue
gases.
[0049] Due to the variety of industrial fuels that can be used,
such as coal, natural gas, various oils (heating and waste oil),
wood and other recycled wastes, along with the various methods,
current and proposed, to generate oxygen, those skilled in the art
will recognize the enormous potential, vis-a-vis commercial and
industrial applicability, of the present combustion system. Fuel
selection can be made based upon availability, economic factors and
environmental concerns. Thus, no one fuel is specified; rather a
myriad, and in fact, all carbon based fuels are compatible with the
present system. Accordingly, the particulate removal stages of the
integrated IPR system may vary.
[0050] As to the supply of oxygen for the oxy-fueled burners
(combustion system), there are many acceptable technologies for
producing oxygen at high purity levels, such as cryogenics,
membrane systems, absorption units, hydrolysis and the like. All
such fuel uses and oxygen supplies are within the scope of the
present invention.
[0051] In general, the use of oxygen fuel fired combustion over
current or traditional air fuel systems offers significant
advantages in many areas. First is the ability to run at precise
stoichiometric levels without the hindrance of nitrogen in the
combustion envelope. This allows for greater efficiency of the fuel
usage, while greatly reducing the NOx levels in the burn
application. Significantly, less fuel is required to achieve the
same levels of energy output, which in turn, reduces the overall
operating costs. In using less fuel to render the same power
output, a natural reduction in emissions results. Fuel savings and
less emissions are but only two of the benefits provided by the
present system. In conjunction with the integrated pollutant
removal (IPR) system, the present oxy-fuel IPR system provides far
greater levels of efficiency and pollution control than known
systems.
[0052] It is anticipated that combustors (e.g., boilers) will be
designed around oxygen fueled combustion systems with integrated
IPR to take full advantage of the benefits of these systems. It is
also anticipated that retrofits or modifications to existing
equipment will also provide many of these benefits both to the
operator (e.g., utility) and to the environment.
[0053] In the present disclosure, the words "a" or "an" are to be
taken to include both the singular and the plural. Conversely, any
reference to plural items shall, where appropriate, include the
singular.
[0054] From the foregoing it will be observed that numerous
modifications and variations can be effectuated without departing
from the true spirit and scope of the novel concepts of the present
invention. It is to be understood that no limitation with respect
to the specific embodiments illustrated is intended or should be
inferred. The disclosure is intended to cover by the appended
claims all such modifications as fall within the scope of the
claims.
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