U.S. patent application number 13/710951 was filed with the patent office on 2013-06-20 for process for the enhancement of power plant with co2 capture and system for realization of the process.
The applicant listed for this patent is Alexander Alekseev, Ramachandran Krishnamurthy, Rob Smith. Invention is credited to Alexander Alekseev, Ramachandran Krishnamurthy, Rob Smith.
Application Number | 20130152595 13/710951 |
Document ID | / |
Family ID | 48608737 |
Filed Date | 2013-06-20 |
United States Patent
Application |
20130152595 |
Kind Code |
A1 |
Alekseev; Alexander ; et
al. |
June 20, 2013 |
PROCESS FOR THE ENHANCEMENT OF POWER PLANT WITH CO2 CAPTURE AND
SYSTEM FOR REALIZATION OF THE PROCESS
Abstract
Improved methods and systems for power plants with CO2 capture
and especially power plants with CO2 capture for enhanced oil
recovery (EOR) purposes.
Inventors: |
Alekseev; Alexander;
(Wolfratshausen, DE) ; Smith; Rob; (Hampshire,
GB) ; Krishnamurthy; Ramachandran; (Chestnut Ridge,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Alekseev; Alexander
Smith; Rob
Krishnamurthy; Ramachandran |
Wolfratshausen
Hampshire
Chestnut Ridge |
NY |
DE
GB
US |
|
|
Family ID: |
48608737 |
Appl. No.: |
13/710951 |
Filed: |
December 11, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61577872 |
Dec 20, 2011 |
|
|
|
Current U.S.
Class: |
60/772 ;
60/39.52 |
Current CPC
Class: |
F01N 3/00 20130101; Y02C
10/04 20130101; Y02E 20/32 20130101; Y02A 50/20 20180101; Y02E
20/34 20130101; B01D 2257/102 20130101; F23C 9/00 20130101; Y02A
50/2342 20180101; B01D 2252/204 20130101; Y02C 20/40 20200801; Y02E
20/344 20130101; Y02E 20/322 20130101; B01D 2258/0283 20130101;
B01D 2256/12 20130101; F23J 2215/50 20130101; F23L 7/007 20130101;
F23L 2900/07001 20130101; B01D 53/265 20130101; B01D 2257/504
20130101; B01D 53/62 20130101 |
Class at
Publication: |
60/772 ;
60/39.52 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Claims
1. A power plant system comprising: a fossil fueled power plant
having an inlet and an exhaust; a flue gas treatment unit
communicating with the exhaust of the power plant; a recycle line
communicating with the flue gas treatment unit and the inlet of the
power plant; an air separation unit communicating with the inlet of
the power plant; an ambient air source communicating with the inlet
of the power plant; wherein at least a portion of a CO.sub.2
enriched gas stream from the flue gas treatment unit is mixed with
oxygen enriched gas from the air separation unit and ambient air
from the ambient air source to form a mixed gas stream that is
delivered by the recycle line to the inlet of the power plant.
2. The power plant system of claim 1 wherein the power plant is a
power plant for an enhanced oil recovery system.
3. The power plant system of claim 1 wherein the power plant is a
gas turbine, a steam generator or a combined gas turbine and steam
generator.
4. The power plant system of claim 1 wherein the air separation
unit is a cryogenic air separation unit.
5. The power plant system of claim 1 further comprising a heater
communicating with the flue gas treatment unit and with the recycle
line, for preheating the CO.sub.2 enriched gas stream.
6. The power plant system of claim 1 further comprising a chemical
processing unit communicating with the flue gas treatment unit
wherein the portion of the CO.sub.2 enriched gas stream that is not
recycled is treated in the chemical processing unit.
7. The power plant system of claim 6 wherein the chemical
processing unit is an amine wash unit.
8. The power plant system of claim 1 wherein the flue gas treatment
unit is a direct contact flue gas cooler or a chilled water direct
contact flue gas cooler.
9. The power plant system of claim 1 wherein the portion of the
CO.sub.2 enriched gas stream that is not recycled is provided to
end users.
10. The power plant system of claim 9 wherein the end user is an
enhanced oil recovery operation.
11. The power plant system of claim 1 wherein the air separation
unit produces a nitrogen enriched gas stream that may be provided
directly to an end user.
12. The power plant system of claim 11 further comprising a mixing
unit communicating with the flue gas treatment unit and with the
air separation unit wherein the portion of the CO.sub.2 enriched
gas stream that is not recycled and the nitrogen enriched gas
stream from the air separation unit are mixed for supply to end
users.
13. A method of enhancing the operation of a power plant
comprising: collecting flue gas from the power plant; recycling at
least a portion of the collected flue gas to the power plant;
mixing the recycled flue gas with air and oxygen enriched gas; and
delivering the mixed gases to the power plant.
14. The method of claim 13 further comprising supplying the oxygen
enriched gas from an air separation unit.
15. The method of claim 13 wherein the oxygen enriched gas is from
50% to 100% oxygen.
16. The method of claim 13 further comprising treating the flue gas
prior to the step of recycling a portion of the flue gas.
17. The method of claim 16 wherein treating the flue gas comprises
processing the flue gas through a direct contact flue gas cooler or
through a chilled water direct contact flue gas cooler.
18. The method of claim 13 further comprising delivering the
portion of the flue gas that is not recycled to an end user.
19. The method of claim 18 wherein the end user is an enhanced oil
recovery operation.
20. The method of claim 13 further comprising producing a nitrogen
enriched gas stream from the air separation unit; and delivering
the nitrogen enriched gas stream to an end user.
21. The method of claim 20 further comprising mixing the portion of
the flue gas that is not recycled with the nitrogen enriched gas
stream; and delivering the mixture to an end user.
22. The method of claim 21 further comprising removing oxygen from
the flue gas prior to mixing with the nitrogen enriched gas
stream.
23. A method of enhancing the operation of a power plant
comprising: collecting flue gas from the power plant; recycling at
least a portion of the collected flue gas to the power plant; and
delivering air and oxygen enriched gas to the power plant.
Description
FIELD OF THE INVENTION
[0001] The present invention generally concerns power plants with
CO.sub.2 capture and especially power plants with CO.sub.2 capture
for enhanced oil recovery (EOR) purposes.
BACKGROUND OF THE INVENTION
[0002] It is known that power plants for the generation of
electrical and thermal energy having gas and/or steam turbines
driven by fossil fuels may be equipped with systems based on
chemical solvent processes (amines, chilled ammonia and others) for
the capture of carbon dioxide (CO.sub.2) from the flue gas
resulting from the combustion of the fossil fuels; the so called
"post combustion carbon capture process".
[0003] It is also known that exhaust gas recirculation can be used
in fossil-fired power plants to control the production of gaseous
emissions, in particular to enrich the CO.sub.2 content of the
exhaust gas, reducing or eliminating the need for costly CO.sub.2
capture.
[0004] It is also known that an alternative technology is the so
called "oxyfuel process" based on combustion of fossil fuels in an
oxygen-enriched stream instead of the ambient air (which contains
approximately 21% by volume of oxygen only). If nitrogen is removed
prior to combustion, the flue gas stream would then have less
nitrogen and the concentration of CO.sub.2 becomes higher, reducing
or eliminating the need for costly CO.sub.2 capture.
[0005] Following any necessary post-treatment, the separated
CO.sub.2 can be forwarded into storage or used for enhanced oil
recovery or other purposes.
[0006] Further information concerning this technical background can
be found in "Developments and innovations in carbon dioxide
(CO.sub.2) capture and storage technology"; Volume 1; Carbon
dioxide (CO.sub.2) capture, transport and industrial applications;
edited by M. Mercedes Maroto-Valer; Woodhead Publishing Limited,
2010, ISBN 978-1-84569-533-0.
[0007] In the post-combustion CO.sub.2 capture system the whole
flue gas flow is processed at low pressure, therefore this system
(apparatus, pipelines, etc.) becomes voluminous and expensive. Some
vessels can become so large, that the system is not feasible as a
one-train solution, therefore several trains working in parallel
are required for realization of such a process.
[0008] One issue with the post-combustion CO.sub.2 capture system
results from the low CO.sub.2 concentration in the flue gas (3-15%
depending on the fuel and combustion system). The efficiency of the
chemical solvent process plant depends on the CO.sub.2
concentration in the flue gas, a low CO.sub.2 concentration
generally resulting in a low efficiency.
[0009] The oxyfuel-based system has a similar problem, i.e. a large
amount of air is required to be treated in the air separation unit
for the production of the oxygen that goes into combustion. The
system therefore becomes large, possibly requiring a multi-train
solution and inefficient.
[0010] Exhaust gas recirculation has the problem that the oxygen
lean recirculation gas, when mixed with incoming ambient air
results in a oxygen depleted/CO.sub.2 enriched air stream for the
power plant that can affect the output, efficiency, stability and
operation of the power plant.
[0011] For all of the above reasons, there remains a need in the
art for improvements to CO.sub.2 capture from a power plant.
SUMMARY OF THE PRESENT INVENTION
[0012] The present invention provides improved techniques for
CO.sub.2 capture from a power plant and reuse thereof that is an
improvement over the techniques known in the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a schematic drawing showing a fossil fuel power
plant with CO.sub.2 capture according to the invention.
[0014] FIG. 2 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture according to the
invention.
[0015] FIG. 3 is a schematic drawing showing a fossil fuel fired
gas turbine cycle power plant with CO.sub.2 capture according to
the invention.
[0016] FIG. 4 is a schematic drawing showing a fossil fuel fired
steam cycle power plant with CO.sub.2 capture according to the
invention.
[0017] FIG. 5 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture for EOR according
to the invention.
[0018] FIG. 6 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture, for providing
CO.sub.2, N.sub.2 and CO.sub.2 /N.sub.2 mixtures for EOR according
to the invention.
[0019] FIG. 7 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture for EOR, having a
direct contact flue gas cooler according to the invention.
[0020] FIG. 8 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture for EOR, having a
chilled water direct contact flue gas cooler according to the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The present invention provides improved techniques for
CO.sub.2 capture from a power plant that is an improvement over the
techniques known in the prior art and particularly to CO.sub.2
capture for EOR (Enhanced Oil Recovery) purposes. One goal of the
present invention is to create an efficient power plant with
CO.sub.2 combustion.
[0022] The process according to the present invention is based on a
combination of the exhaust gas recirculation process, oxy-fuel
process and post combustion process (chemical solvent process). A
portion of the exhaust gas from the power plant is recirculated to
the air inlet and mixed with both incoming ambient air and an
oxygen rich gas stream. The oxygen content of the mixed stream is
adjusted by addition of the oxygen rich stream that may be provided
from an air separation unit, or other appropriate source. This
mixture results in a CO.sub.2 enriched flue gas from the power
plant that is partly recycled to the power plant with the remainder
flowing to the chemical solvent process unit, where the CO.sub.2 is
separated. This process of flue gas recycle and oxygen enrichment
are used to control the parameters of the combustion process for
the power plant and to make the CO.sub.2 separation easier.
[0023] The invention will be described in greater detail with
reference to the drawing figures, wherein like components are
labeled with like reference numerals. In particular, FIG. 1 is a
schematic drawing showing a fossil fuel power plant with CO.sub.2
capture according to the invention. In FIG. 1, a power plant 100 is
fueled by a fossil fuel source 10 that may be a solid, liquid or
gaseous source, in addition to air from an air source 20, and an
oxygen rich gas 32 from an air separation unit (ASU) 30 that is
supplied by an air source 34. The oxygen rich gas 32 is preferably
50% to 100% oxygen. The ASU separates the air supplying the oxygen
rich gas 32 to the power plant 100 and releasing a waste stream of
nitrogen enriched gas 36. The power plant 100 emits flue gas 42
that is treated in a flue gas treatment unit 40. The flue gas
treatment unit 40 operates to cool the flue gas 42 and to remove
water 44 and various waste 46 while emitting a CO.sub.2 enriched
gas stream 48. Part of the CO.sub.2 enriched gas stream 48 is
recycled and mixed with the air from the air source 20 and the
oxygen rich gas 32 prior to being fed to the power plant 100. An
optional process of heating part of the flue gas 42 in a heater 43
and then mixing the pre-heated gas with the recycled portion of
CO.sub.2 enriched gas stream 48 can be employed. This allows for
pre-heating of the feed gas to the power plant 100. The CO.sub.2
enriched gas stream 48 that is not recycled to the power plant 100
is processed for waste removal in a chemical solvent process unit
50 that emits a waste stream 52 and a CO.sub.2 containing gas 54.
The CO.sub.2 containing gas 54 can then be compressed and dried and
sent to storage units 60 from which it can be supplied for end user
processes 70.
[0024] FIG. 2 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture according to the
invention. The system shown in FIG. 2 is the same as that shown in
FIG. 1 with the exception that the power plant 100 has been replace
with a combined gas turbine and steam generator plant. In
particular, the mixed CO.sub.2 air and oxygen rich gas is delivered
to a gas turbine 200 with the flue gas 42 passing through a heat
recovery steam generator with rankine cycle 205 prior to the
delivery to the flue gas treatment unit 40. The heat recovery steam
generator can optionally be supplied with fossil fuel from the
fossil fuel source 10. Further, optionally the recycle CO.sub.2
stream can be fed directly to the plant 200 without premixing with
air or oxygen enriched gas.
[0025] FIG. 3 is a schematic drawing showing a fossil fuel fired
gas turbine cycle power plant with CO.sub.2 capture according to
the invention. The system shown in FIG. 3 is the same as that shown
in FIG. 1 with the exception that the power plant 100 is more
specifically identified as a gas turbine. In particular, the mixed
CO.sub.2 air and oxygen rich gas is delivered to a gas turbine 300
with the flue gas 42 delivered to the flue gas treatment unit
40.
[0026] FIG. 4 is a schematic drawing showing a fossil fuel fired
steam cycle power plant with CO.sub.2 capture according to the
invention. The system shown in FIG. 4 is the same as that shown in
FIG. 1 with the exception that the power plant 100 is more
specifically identified as a steam turbine. In particular, the
mixed CO.sub.2 air and oxygen rich gas is delivered to a steam
turbine 400 with the flue gas 42 delivered to the flue gas
treatment unit 40.
[0027] FIG. 5 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture for EOR according
to the invention. The system shown in FIG. 5 is the same as that
shown in FIG. 2 with the exception that the end user is
specifically identified as an EOR. In particular, CO.sub.2 62 can
be delivered from storage unit 60 to an EOR user 72. Alternatively,
the nitrogen rich gas 36 from the ASU 30 can be delivered to and
EOR user 74. In a further alternative, CO.sub.2 62 from the storage
unit 60 can be mixed with the nitrogen rich gas 36 from the ASU 30
and delivered as a mixture to an EOR user 76.
[0028] FIG. 6 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture, for providing
CO.sub.2, N.sub.2 and CO.sub.2/N.sub.2 mixtures for EOR according
to the invention. The system shown in FIG. 6 is the same as that
shown in FIG. 5 with the exception that the CO.sub.2/N.sub.2 gas
mixture is derived in a different manner. In particular, part of
the recycle CO.sub.2 stream can be treated in oxygen removal unit
600 to remove oxygen and provide a N.sub.2 enriched stream 602 that
is then mixed with the CO.sub.2 containing gas 54 to form a
CO.sub.2/N.sub.2 gas mixture that is delivered to storage unit 60
and delivery to EOR user 76. The oxygen removal unit 600 can be any
suitable unit, such as a catalytic de-oxo unit with CH.sub.4 or
H.sub.2 from an external source or from reforming of natural gas,
or a conventional burner with CH.sub.4 or H.sub.2.
[0029] FIG. 7 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture for EOR, having a
direct contact flue gas cooler according to the invention. The
system shown in FIG. 7 is the same as that shown in FIG. 5 with the
exception that the flue gas treatment unit has been replaced with a
more specific water coolant treatment unit and the chemical solvent
process has been more specifically identified as an amine wash
plant. In particular, the flue gas 42 is treated in water coolant
treatment unit 700 to remove water 44 and waste 46 prior to being
recycled or further treated in amine wash plant 750. In this system
the ASU 30 can be a cryogenic ASU.
[0030] FIG. 8 is a schematic drawing showing a fossil fuel fired
combined cycle power plant with CO.sub.2 capture for EOR, having a
chilled water direct contact flue gas cooler according to the
invention. The system shown in FIG. 8 is the same as that shown in
FIG. 7 with the exception that the water coolant treatment unit is
specifically identified as a chilled water direct contact flue gas
cooler. In particular, the flue gas 42 is treated in chilled water
direct contact flue gas cooler 800 to remove water 44 and waste 46
prior to being recycled or further treated in amine wash plant 750.
This system may also employ a cryogenic ASU.
[0031] The invention offers several advantages. By using oxygen
enriched air from an ASU as part of the recycle feed to the power
plant, the CO.sub.2 concentration in the recycle gas is greater
than a feed stream because there is less nitrogen in the feed. This
makes the power plant more efficient. In addition, since less
nitrogen is entering the system, there is a greater concentration
of CO.sub.2 in the flue gas. This makes the chemical solvent
treatment process more efficient and increases the efficiency of
the whole power plant system. In addition, only a fraction of the
air required needs to be separated in the air separation unit when
operating according to the invention. Therefore the irreversibility
caused by the air separation is reduced. The air separation plant
can be more compact in the invention because of the reduced air
flow requirement and the size of the absorption plant is also
reduced because of the lower nitrogen concentration in the flue
gas. It is therefore possible for the system of the invention to be
used in either a single-train- or double-train solution, which
allows for simpler control methodology.
[0032] By using the invention, the mixed gas provided to the power
plant is oxygen enriched and therefore the output, efficiency,
stability and operation of the power plant is enhanced. Further,
the system of the invention can advantageously be used for
retrofitting of existing power plants, because only minor changes
are required to the power plant input.
[0033] It is anticipated that other embodiments and variations of
the present invention will become readily apparent to the skilled
artisan in the light of the foregoing description, and it is
intended that such embodiments and variations likewise be included
within the scope of the invention as set out in the appended
claims.
* * * * *