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Title:
PROCESS FOR CARBON DIOXIDE RECAPTURE WITH IMPROVED ENERGY RECAPTURE
Document Type and Number:
WIPO Patent Application WO/2018/200526
Kind Code:
A1
Abstract:
A method includes providing a stream containing carbon dioxide and at least one other condensable component; pressuring the stream containing carbon dioxide and at least one other condensable component to thereby produce a pressurized stream; and indirectly exchanging thermal energy between the pressurized stream and a thermal- energy accepting stream including a boilable component. A method includes providing a first stream containing carbon dioxide; adsorbing at least a portion of the carbon dioxide in the first stream in an adsorbing means; desorbing at least a portion of the carbon dioxide in the adsorbing means to obtain a desorbed carbon dioxide stream; and compressing the desorbed carbon dioxide stream immediately following said step of desorbing.

Inventors:
KEISER DANIEL R (US)
LOPEZ ANDRES S (US)
Application Number:
PCT/US2018/029142
Publication Date:
November 01, 2018
Filing Date:
April 24, 2018
Export Citation:
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Assignee:
OXY USA INC (US)
International Classes:
B01D1/28; B01D53/14; B01D53/62; C01B32/50; F01K3/26; F26B9/02; F26B21/10
Domestic Patent References:
WO2016005226A12016-01-14
Foreign References:
US4270937A1981-06-02
US20110265477A12011-11-03
US20100050637A12010-03-04
US20100024476A12010-02-04
Attorney, Agent or Firm:
REGINELLI, Arthur M. et al. (US)
Download PDF:
Claims:
CLAIMS

What is claimed is:

1. A method of recapturing carbon dioxide comprising steps of:

(i) providing a stream containing carbon dioxide and at least one other condensable component;

(ii) pressuring the stream containing carbon dioxide and at least one other condensable component to thereby produce a pressurized stream; and

(iii) indirectly exchanging thermal energy between the pressurized stream and a thermal- energy accepting stream including a boilable component.

2. The method of any of the preceding claims, wherein the step of indirectly exchanging thermal energy results in condensing at least a portion of the at least one condensable component and boiling at least a portion of the boilable component.

3. The method of any of the preceding claims, wherein the step of pressuring occurs prior to any step of providing the stream containing carbon dioxide and at least one other condensable component to a heat exchanger.

4. The method of any of the preceding claims, wherein the stream containing carbon dioxide and at least one other condensable component is provided as an outlet stream of a carbon dioxide adsorbing and desorbing process, wherein the step of pressuring is immediately sequential following the stream containing carbon dioxide and at least one other condensable component exiting the carbon dioxide adsorbing and desorbing process.

5. The method of any of the preceding claims, wherein the step of indirectly exchanging thermal energy between the pressurized stream and the thermal- energy accepting stream includes the condensable component in the pressurized stream having a condensation temperature at least 5 °F greater than the boiling temperature of the boilable component in the thermal-energy accepting stream.

6. A method of recapturing carbon dioxide from a stream including carbon dioxide comprising steps of:

(i) providing a first stream containing carbon dioxide;

(ii) adsorbing at least a portion of the carbon dioxide in the first stream in an adsorbing means;

(iii) desorbing at least a portion of the carbon dioxide in the adsorbing means to obtain a desorbed carbon dioxide stream; and

(iv) compressing the desorbed carbon dioxide stream immediately following said step of desorbing.

7. The method of any of the preceding claims, wherein the first stream containing carbon dioxide further includes a condensable component, wherein said step of compressing produces a pressurized stream, the method further comprising a step of:

(v) indirectly exchanging thermal energy between the pressurized stream and a thermal- energy accepting stream having a boilable component therein, wherein the condensable component in the pressurized stream has a condensation temperature at least 5 °F greater than the boiling temperature of the boilable component in the thermal- energy accepting stream.

8. The method of any of the preceding claims, wherein the thermal- energy accepting stream includes water, such that the step of indirectly exchanging thermal energy results in vaporization of a substantial portion of the water in the thermal- energy accepting stream upon sufficient thermal energy exchange.

9. The method of any of the preceding claims, wherein the at least one other condensable component is water vapor.

10. The method of any of the preceding claims, wherein the condensing of the water vapor subsequently results in a separate condensate stream from a knock out drum, the method further comprising the step of returning the condensate stream to the thermal-energy accepting stream.

11. The method of any of the preceding claims, wherein the stream containing carbon dioxide includes 50% by volume carbon dioxide.

12. The method of any of the preceding claims, wherein the stream containing carbon dioxide includes from 10% to 90% by volume carbon dioxide.

13. The method of any of the preceding claims, wherein the adsorbing means is a solid sorbent.

14. The method of any of the preceding claims, wherein the thermal- energy accepting stream is water.

15. The method of any of the preceding claims, wherein the step of desorbing occurs in a solid sorbent, wherein the vaporization of a substantial portion of the water in the thermal-energy accepting stream produces a steam stream, wherein the steam stream is routed back to the solid sorbent.

16. The method of any of the preceding claims, wherein the absorbing means is an amine solution within an amine system.

17. The method of any of the preceding claims, wherein the thermal- energy accepting stream includes amine, such that the step of indirectly exchanging thermal energy results in vaporization of a substantial portion of the amine in the thermal- energy accepting stream upon sufficient thermal energy exchange.

18. The method of any of the preceding claims, wherein the step of desorbing occurs in a regenerator, wherein the thermal-energy accepting stream is routed from the bottom of the regenerator, to a heat exchanger where the step of indirectly exchanging thermal energy is performed, and back to a side inlet of the regenerator.

19. The method of any of the preceding claims, wherein the stream containing carbon dioxide and at least one other condensable component is provided as an outlet stream of a fuel cell, wherein the step of pressuring is immediately sequential following the stream containing carbon dioxide and at least one other condensable component exiting the fuel cell.

20. The method of any of the preceding claims, wherein the stream containing carbon dioxide and at least one other condensable component is provided as an outlet stream of an oxy-fuel combustion process, wherein the step of pressuring is immediately sequential following the stream containing carbon dioxide and at least one other condensable component exiting the oxy-fuel combustion process.

Description:
PROCESS FOR CARBON DIOXIDE RECAPTURE WITH

IMPROVED ENERGY RECAPTURE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 62/489,133 and U.S. Provisional Application Serial No. 62/489,141, both of which were filed on April 24, 2017, and are incorporated herein by reference.

FIELD OF THE INVENTION

[0002] Embodiments of the present invention relate to CO2 recapture systems that have enhanced recovery of thermal energy. Specific embodiments include C0 2 sorption- desorption processes which include a C0 2 desorption step that produces a stream containing CO2 and steam. This stream is subsequently pressurized and water present in the stream is separated by condensation at elevated temperatures. Energy is recovered from this condensing water to produce low-pressure steam that can be used in the C0 2 desorption step.

BACKGROUND OF THE INVENTION

[0003] It has been desirable to capture C0 2 produced in combustion processes. For example, in the combustion of fossil fuels for the generation of power, techniques have been developed to capture and isolate the carbon dioxide product. Once captured and isolated, the C0 2 can be used in a variety of uses including enhanced oil recovery processes. To this end, the C0 2 is typically pressurized after isolation.

[0004] An exemplary process is disclosed in U.S. Patent No. 8,900,347, which discloses a method where a component, such as carbon dioxide, is adsorbed on an adsorbent material. A desorption fluid, which may include steam, is provided to desorb the carbon dioxide. This results in a stream containing the carbon dioxide and the steam. This stream may subsequently be cooled to condense the steam from the carbon dioxide. [0005] One technique for the capture and isolation of C0 2 from combustion streams is an absorption-desorption process. According to these processes, C0 2 is absorbed to an absorbent and then subsequently released in a desorption step. For example, a common process involves the treatment of C0 2 containing gaseous streams within an absorber that includes an aqueous solution of an amine, such as an alkanolamine, which acts as the absorbent. The C0 2 -rich amine solution is then transferred to a regeneration unit where the C0 2 -rich amine is heated with low-pressure steam to strip the amine of the

C0 2 and thereby produce a gaseous stream of C0 2 , steam, and amine solvent.

[0006] Most C0 2 recapture processes, such as the amine process, ultimately produce streams that include a mixture of C0 2 and steam (as well as other constituents as the process may provide) via the desorption process. In order to obtain a highly concentrated stream of C0 2 , the C0 2 must be separated from the steam. Once separated, the C0 2 is typically pressurized. In separating the steam from the C0 2 , it is conventional to condense the steam and then subsequently pressurize the C0 2 -rich stream.

SUMMARY OF THE INVENTION

[0007] One or more embodiments of the present invention provide a method including steps of providing a stream containing carbon dioxide and at least one other condensable component; pressuring the stream containing carbon dioxide and at least one other condensable component to thereby produce a pressurized stream; and indirectly exchanging thermal energy between the pressurized stream and a thermal- energy accepting stream including a boilable component.

[0008] One or more embodiments of the present invention provide a method including steps of providing a first stream containing carbon dioxide; adsorbing at least a portion of the carbon dioxide in the first stream in an adsorbing means; desorbing at least a portion of the carbon dioxide in the adsorbing means to obtain a desorbed carbon dioxide stream; and compressing the desorbed carbon dioxide stream immediately following said step of desorbing. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Fig. 1 is a flow chart representation of a process according to one or more embodiments of the present invention.

[0010] Fig. 2 is a flow chart representation of a process according to one or more embodiments of the present invention.

[0011] Fig. 3 is a flow chart representation of a process according to one or more embodiments of the present invention.

[0012] Fig. 4 is a flow chart representation of a process according to one or more embodiments of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0013] Embodiments of the present invention are based, at least in part, on the discovery of a carbon dioxide (C0 2 ) recapture process that includes pressurizing a desorbed C0 2 stream, which includes a mixture of C0 2 and steam, and subsequently condensing the pressurized steam while utilizing the thermal energy released during condensation (i.e. the latent heat of condensation). Embodiments produce low-pressure steam, which can advantageously be used in the subsequent desorption of C0 2 . The present invention advantageously includes the ability to utilize the energy from condensation, such as for the production of low-pressure steam. Embodiments of the present invention first pressurize the desorbed stream, which advantageously provides a means by which the latent heat of condensation can be utilized, such as for the production of low-pressure steam.

PROCESS OVERVIEW

[0014] One or more embodiments of the invention can be described with reference to Fig. 1, which shows a C0 2 recapture process 10, which may also be described as an energy-integrated process 10. C0 2 recapture process 10 includes a C0 2 sorption- desorption process 12, which may also be referred to as a C0 2 adsorption- desorption process 12, which produces an outlet vapor phase stream 14' including steam and C0 2 . Vapor phase stream 14', which may also be referred to as a C0 2 -desorbed stream 14', is provided to a compressor 16. Within compressor 16, C0 2 -desorbed stream 14' is pressurized to form a pressurized stream 18', which may also be referred to as a first- stage pressurized stream 18'.

[0015] First-stage pressurized stream 18' is introduced to a first pass of a heat exchanger 20, which may also be described as a boiler 20 or steam boiler 20, and an opposing stream 22', which may also be referred to as a thermal- energy accepting stream 22', is introduced to the opposing pass of heat exchanger 20. Opposing stream 22' may be provided by a water source, such as a boiler feed water source, or may be a process stream. Within heat exchanger 20, at least a portion of the water within pressurized stream 18' is condensed at elevated pressure, where elevated pressure is defined as the extra pressure provided by compressor 16 to pressurized stream 18' compared to vapor phase stream 14'. This condensation of stream 18' releases the latent heat of condensation to thereby transfer this thermal energy to opposing stream 22' in accord with the design properties of heat exchanger 20. Based on this thermal energy transfer, at least a portion of the liquid water within opposing stream 22' is vaporized to become water vapor. Heat exchanger 20 may be a shell-and-tube heat exchanger as generally known to those skilled in the art.

[0016] In order to achieve this thermal energy transfer, first-stage pressurized stream 18' includes a suitable elevated pressure such that the increased condensation temperature is higher than the temperature at which opposing stream 22' will boil to produce steam in stream 24'. It should be appreciated that by first pressurizing stream 14' including C0 2 and steam to produce pressurized stream 18', water in pressurized stream 18' is condensed at temperatures above the condensation temperature of the water in vapor phase stream 14'. As a result, the energy of condensation, coupled with the temperature at which the energy is released, is sufficient to vaporize at least a portion of the water 22 in opposing stream 22'.

[0017] In one or more embodiments, the temperature at which a substantial part of the water in pressurized stream 18' will condense is at least 5 °F, in other embodiments, at least 10 °F, in other embodiments, at least 15 °F, in other embodiments, at least 20 °F, in other embodiments, at least 25 °F, in other embodiments, at least 30 °F, in other embodiments, at least 35 °F, in other embodiments, at least 50 °F, in other embodiments, at least 75 °F, and in other embodiments, at least 100 °F, more than the temperature at which the water 22 in opposing stream 22' will boil. In one or more embodiments, the temperature at which a substantial part of the water in pressurized stream 18' will condense is at most 10 °F, in other embodiments, at most 15 °F, in other embodiments, at most 20 °F, in other embodiments, at most 25 °F, in other embodiments, at most 30 °F, in other embodiments, at most 35 °F, in other embodiments, at most 40 °F, in other embodiments, at most 75 °F, in other embodiments, at most 100 °F, and in other embodiments, at most 125 °F, more than the temperature at which the water 22 in opposing stream 22' will boil. In one or more embodiments, the temperature at which a substantial part of the water in pressurized stream 18' will condense is from 2 °F to 40 °F, in other embodiments, from 5 °F to 30 °F, and in other embodiments, from 10 °F to 20 °F, more than the temperature at which the water 22 in opposing stream 22' will boil.

[0018] As used here, the term "substantial" may be defined as greater than 50% of the water condensing. In one or more embodiments, at least 80%, in other embodiments, at least 90%, in other embodiments, at least 95%, in other embodiments, at least 98%, in other embodiments, at least 99%, of the water in pressurized stream 18' condenses via passing through heat exchanger 20.

[0019] In one or more embodiments, a substantial portion of the water 22 in opposing stream 22' may be vaporized, where the term "substantial" may be defined as greater than 50%. In one or more embodiments, at least 70%, in other embodiments, at least 80%, in other embodiments, at least 90%, in other embodiments, at least 95%, in other embodiments, at least 98%, in other embodiments, at least 99%, in other embodiments, about 100%, of the water 22 in opposing stream 22' may be vaporized.

[0020] In one or more embodiments, a substantial portion of the latent heat of condensation of stream 18' may be transferred to opposing stream 22', where the term "substantial" may be defined as greater than 50%. In one or more embodiments, at least 70%, in other embodiments, at least 80%, in other embodiments, at least 90%, in other embodiments, at least 95%, in other embodiments, at least 99%, of the latent heat of condensation of stream 18' may be transferred to opposing stream 22'.

[0021] In one or more embodiments, compressor 16 may utilize a suitable compression ratio in order to achieve the above described temperature difference, where compression ratio may be defined as the absolute pressure of the compressor discharge divided by the absolute pressure of the compressor suction. In one or more embodiments, the compression ratio of compressor 16 is at least 1.1, in other embodiments, at least 1.4, in other embodiments, at least 1.7, in other embodiments, at least 2.0, in other embodiments, at least 2.5, in other embodiments, at least 2.7, and in other embodiments, at least 3.0. In one or more embodiments, the compression ratio of compressor 16 is at most 3.3, in other embodiments, at most 3.0, in other embodiments, at most 2.5, in other embodiments, at most 2.0, in other embodiments, at most 1.5, and in other embodiments, at most 1.3. In one or more embodiments, the compression ratio of compressor 16 is from 1.1 to 3.3, in other embodiments, from 1.5 to 2.5, and in other embodiments, from 1.7 to 2.3.

[0022] In one or more embodiments, compressor 16 may have an inlet pressure of at least -5 psig, in other embodiments, at least 2 psig, and in other embodiments, at least 3 psig. In one or more embodiments, compressor 16 may have an inlet pressure of at most 50 psig, in other embodiments, at most 10 psig, and in other embodiments, at most 7 psig. In one or more embodiments, compressor 16 may have an inlet pressure of from -5 psig to 50 psig, in other embodiments, from 2 psig to 10 psig, and in other embodiments, from 3 psig to 7 psig.

[0023] It is understood that this temperature difference between the temperature at which the water in pressurized stream 18' will condense and the temperature at which the water 22 in opposing stream 22' will boil enables thermal energy transfer from stream 18' to stream 22'. In embodiments of the invention, this thermal energy transfer between stream 18' and stream 22' is sufficient to convert at least 50% of the liquid water 22 in stream 22' to steam 24 in stream 24'. Thus, steam 24 can advantageously be utilized as an inlet stream for CO2 adsorption-desorption process 12, such as being utilized to desorb C0 2 . [0024] Pressurized stream 18' exits heat exchanger 20 as stream 26' and enters a first pass of heat exchanger 28, which may also be described as interstage cooler 28. Interstage cooler 28 serves to further reduce the temperature of stream 20' in order to condense residual water in stream 20' and to improve subsequent compressing efficiency. The opposing stream 30' of interstage cooler 28 is water 32, such as cooling water or boiler feed water. Stream 30' exits interstage cooler 28 as pre-heated boiler feed water stream 34' and may be routed back to opposing stream 22'. Stream 26' exits interstage cooler 28 as stream 36', which enters a knock out drum 38 for separating condensate via a condensate stream 40'. Condensate stream 40' exiting knock out drum 38 may be treated, such as at treatment 42, and may be routed back to opposing stream 22'.

[0025] A gaseous stream 44', which includes C0 2 and a minor amount of uncondensed water, and which may be referred to as a product stream 44' or an intermediary product stream 44', may be suitably utilized as a product stream. In one or more embodiments, intermediary product stream 44' may be supplied to further processing, such as to remove the remaining water. In one or more embodiments, intermediary product stream 44' may be further pressurized. Any number of additional pressurization compression stages may be utilized. An exemplary product stream is for utilization with an enhanced oil recovery process.

[0026] As will be further described, C0 2 recapture process 10 may include an additional compressor, and associated equipment, such as at unit operation 46, in addition to compressor 16. The additional compressor may be after compressor 16. The one or more additional compressor stages may be utilized to increase the pressure based on the intended use for the product stream.

PROCESS OVERVIEW (SOLID SORBENT)

[0027] One or more embodiments of the invention operate in conjunction with a C0 2 recapture system that employs a solid sorbent. For example, as shown in Fig. 2, C0 2 recapture process 100, which may also be described as an energy- integrated process 100, includes a C0 2 adsorption-desorption process 102, which generally includes means for adsorbing C0 2 and means for desorbing C0 2 , such as solid sorbents. In one or more embodiments, the solid sorbent for adsorbing C0 2 and the solid sorbent for desorbing C0 2 are the same, such as the solid sorbent being in a first position for adsorbing C0 2 and then moving to a second position for desorbing C0 2 . In one or more embodiments, the adsorbing and desorbing of C0 2 includes a solid sorbent with a valve system to accomplish a first step of adsorbing C0 2 in the solid sorbent and a subsequent step of desorbing C0 2 from the solid sorbent. One or more additional details regarding C0 2 adsorption-desorption process 102 may be disclosed in U.S. Pat. Nos. 7,314,847; 8,163,066; 8,202,350; 8,591,627; 8,888,895; 9,073,005; 9,120,049; 9,146,035; 9,168,484; 9,446,343; and International Pub. Nos. WO2016011032 and WO2014015243, all of which are incorporated herein by reference.

[0028] C0 2 adsorption-desorption process 102, which generally includes a C0 2 - containing inlet stream (not shown), produces an outlet vapor phase stream 104' including steam and C0 2 , which may also be referred to as a mixture 104' of carbon dioxide and steam or C0 2 -desorbed stream 104'. In one or more embodiments, vapor phase stream 104' may have a composition of about 50% C0 2 by volume and the balance water vapor. In one or more embodiments, vapor phase stream 104' may have a composition of greater than 10% C0 2 by volume, in other embodiments, greater than

40% C0 2 by volume, and the balance water vapor. In one or more embodiments, vapor phase stream 104' may have a composition of less than 90% C0 2 by volume, in other embodiments, less than 60% C0 2 by volume, and the balance water vapor. In one or more embodiments, vapor phase stream 104' may include trace amounts of exhaust gases formed in the combustion of hydrocarbons.

[0029] Vapor phase stream 104' is provided to a compressor 106. Within compressor 106, C0 2 -desorbed stream 104' is pressurized to form a pressurized stream 108', which may also be referred to as a first-stage pressurized stream 108'. Compressor 106 may utilize any of the above-described compression ratios and inlet pressures. [0030] First-stage pressurized stream 108' is introduced to heat exchanger 110, which may also be described as a steam boiler 110. Within heat exchanger 110, at least a portion of the water within stream 108' is condensed at elevated pressure, and thermal energy is transferred to water contained in an opposing pass water stream 112'. The water may be provided by a water source, such as a boiler feed water make-up source 114, or by a pre-heated water stream, as will be further described herein, or a combination of pre-heated water and make-up. Opposing pass water stream 112' may also be referred to as thermal- energy accepting stream 112'.

[0031] Advantageously, the thermal energy exchanged from first-stage pressurized stream 108' to opposing pass water stream 112' is sufficient to vaporize water in stream 112' to produce a low-pressure steam stream 116'. It should be appreciated that by first pressurizing C0 2 -desorbed stream 104' including C0 2 and steam, water in pressurized stream 108' is condensed at temperatures above the condensation temperature of the water in stream 104'. As a result, the energy of condensation coupled with the temperature at which the energy is released is sufficient to vaporize water in stream 112'. The above description relating to the difference between the temperature at which the water in the pressurized stream will condense and the temperature at which the water in the opposing stream will boil also applies here.

[0032] After passing through heat exchanger 110, heat-exchanged stream 110' proceeds to a knock out drum 126 for separating condensed water via a condensate water stream 128'. Condensate water stream 128' exiting knock out drum 126 may be routed back to opposing pass water stream 112'.

[0033] A gaseous stream 130', which includes C0 2 and uncondensed water, and which may be referred to as a second-stage inlet stream 130', is introduced to a second- stage compressor 132, which pressurizes second-stage inlet stream 130' to form a second-stage pressurized stream 134'.

[0034] Second-stage pressurized stream 134' is introduced to heat exchanger 135, which may also be described as a steam boiler 135. Within heat exchanger 135, at least a portion of the water within stream 134' is condensed at elevated pressure, and thermal energy is transferred to water contained in an opposing pass water stream 137'. The water may be provided by a water source, such as a boiler feed water make-up source 114, or by a pre-heated water stream, as will be further described herein, or a combination of pre-heated water and make-up. Opposing pass water stream 137' may also be referred to as thermal- energy accepting stream 137'.

[0035] Advantageously, the thermal energy exchanged from second-stage pressurized stream 134' to opposing pass water stream 137' is sufficient to vaporize water in stream 137' to produce a low-pressure steam stream 139'. It should be appreciated that by first pressurizing CC^-desorbed stream 130' including CO2 and steam, water in pressurized stream 134' is condensed at temperatures above the condensation temperature of the water in stream 130'. As a result, the energy of condensation coupled with the temperature at which the energy is released is sufficient to vaporize water in stream 137'. The above description relating to the difference between the temperature at which the water in the pressurized stream will condense and the temperature at which the water in the opposing stream will boil also applies here.

[0036] Low-pressure steam stream 139' joins low-pressure steam stream 116' to form a return steam stream 141', which may be advantageously returned to C0 2 adsorption-desorption process 102 to be used for desorbing C0 2 within CO2 adsorption- desorption process 102. A make-up steam stream 143' may also be provided to C0 2 adsorption-desorption process 102.

[0037] After passing through heat exchanger 135, heat-exchanged stream 145' proceeds to an interstage cooler 118. Interstage cooler 118 serves to further reduce the temperature of stream 145' in order to condense residual water in stream 145' and to improve subsequent compressing efficiency. Interstage cooler 118 may use boiler feed water, cooling water, air, or other thermal energy accepting streams to cool stream 145'.

[0038] After passing through interstage cooler 118, cooled stream 140' proceeds to a knock out drum 142 for separating condensed water via a condensate water stream 144'. Condensate water stream 144' exiting knock out drum 142 may be routed back to opposing pass water stream 112'. Condensate water stream 144' and condensate water stream 128' may be provided to a treatment system 146, such as water polishing system 146, for minor treatment to remove impurities before being used with stream 112'.

[0039] A gaseous stream 148', which includes C0 2 and a minor amount of uncondensed water, and which may be referred to as product stream 148' or intermediary product stream 148', exits knock out drum 142 and may be suitably utilized as a product stream. In one or more embodiments, intermediary carbon dioxide product stream 148' may be supplied to further processing, such as to remove the remaining water. In one or more embodiments, intermediary product stream 148' may be further pressurized in additional compression stages in order to sufficiently pressurize the stream for suitable use as a product stream. Any number of additional pressurization compression stages may be utilized. An exemplary product stream is for utilization with an enhanced oil recovery process.

PROCESS OVERVIEW (AMINE)

[0040] One or more embodiments of the invention operate in conjunction with a C0 2 recapture system that employs an amine scrubbing process. For example, as shown in Fig. 3, C0 2 recapture process 200 includes amine scrubbing process 202, which may also be described as C0 2 absorption-desorption process 202 or C0 2 recapture amine process 202, integrated with C0 2 recovery process 204. Amine scrubbing process 202 includes amine regenerator column 208, which receives rich-amine solution 206 via rich- amine stream 210'. As those of ordinary skill in the art appreciate, rich-amine solution 210 is provided by an absorption subprocess (not shown) wherein C0 2 , such as from a sour gas stream or power plant flue gas, is absorbed to a rich amine solvent within an aqueous solution. In one or more embodiments, the amine is an alkanol amine, such as diethanolamine (DEA), monoethanolamine (MEA), methyldiethanolamine (MDEA), diisopropanolamine (DIPA), aminoethoxyethanol (Diglycolamine) (DGA), and combinations thereof.

[0041] Within regenerator 208, a heated lean amine solution stream 212', which may also be referred to as vaporized stream 212', is provided to regenerator 208 to thereby strip C0 2 from the rich amine solution (i.e., C0 2 is desorbed from the amine), where the stripping of C0 2 occurs upon providing sufficient heat. This produces C0 2 desorbed stream 214', which includes a mixture of steam, CO2, and amine solvent.

[0042] Liquid amine solution exits regenerator 208 as lean-amine solution 216 via stream 216'. At least a portion of lean-amine stream 216' is routed back to the absorption subprocess (not shown), as generally known to those skilled in the art. At least a portion of lean-amine stream 216' may be routed to amine solvent boiler 219 and amine solvent boiler 230 as stream 218', where a substantial portion of stream 218' is converted to a vapor to form vaporized stream 212'. Then, vaporized stream 212' is reintroduced to regenerator 208. In one or more embodiments, at least a portion of lean-amine stream 216' may be routed to reboiler 220 as stream 220', to provide further heat input to regenerator 208, such as for a start-up as generally known to those skilled in the art.

[0043] Consistent with the explanation provided above with respect to Fig. 1, C0 2 desorbed stream 214', which is a vapor stream of carbon dioxide, steam, and amine, is routed to a first-stage compressor 222. Within compressor 222, stream 214' is pressurized to form a first-stage pressurized stream 224'. In one or more embodiments, vapor phase stream 214' may have a composition of about 50% C0 2 by volume and the balance water vapor and amine. In one or more embodiments, vapor phase stream 214' may have a composition of greater than 5% C0 2 by volume, in other embodiments, greater than 40% C0 2 by volume, and the balance water vapor and amine. In one or more embodiments, vapor phase stream 214' may have a composition of less than 80% C0 2 by volume, in other embodiments, less than 60% C0 2 by volume, and the balance water vapor and amine. In one or more embodiments, vapor phase stream 214' may include hydrogen sulfide or other gases generally found in known sour gases. Compressor 222 may utilize any of the above-described compression ratios and inlet pressures.

[0044] First-stage pressurized stream 224' is introduced to heat exchanger 219, which may also be described as amine solvent boiler 219. Consistent with the description above, it is desired that a sufficient temperature difference exists between the temperature at which the water and amine in the pressurized stream will condense and the temperature at which the boilable component in the opposing stream will boil. This generates sufficient vaporization of the water and amine in an opposing stream 228' of amine solvent boiler 219. As said above, opposing stream 228' of amine solvent boiler 219 is lean amine from regenerator 208.

[0045] Advantageously, the thermal energy exchanged from first-stage pressurized stream 224' to opposing stream 228' is sufficient to vaporize a substantial amount of the water and amine in stream 228' to produce vaporized stream 212'. It should be appreciated that by first pressurizing stream 214', first-stage pressurized stream 224' is condensed at temperatures above the condensation temperature of the water and amine in stream 214'. As a result, the energy of condensation coupled with the temperature at which the energy is released is sufficient to vaporize at least a portion of the water and amine in stream 228'. The above description relating to the difference between the temperature at which the water and amine in the pressurized stream will condense and the temperature at which the water and amine in the opposing stream will boil also applies here.

[0046] After passing through heat exchanger 219, heat-exchanged stream 226' is routed to a knock out drum 232 for separating a gaseous stream 236' from condensed amine solution in a condensate aqueous amine solution stream 232'. Stream 232' may be routed to a reflux drum 234 to return the solution back to regenerator 208. A pump may or may not be required to return the amine solution to regenerator 208.

[0047] Gaseous stream 236', which may also be referred to as second-stage inlet stream 236' and which includes C0 2 , steam, and amine, is introduced to a second-stage compressor 238, which pressurizes second-stage inlet stream 236' to form a second-stage pressurized stream 240'. Compressor 238 may utilize any of the above-described compression ratios and inlet pressures.

[0048] Second-stage pressurized stream 240' proceeds to heat exchanger 230, which may also be described as amine solvent boiler 230. Consistent with the description above, it is desired that a sufficient temperature difference exists between the temperature at which the water and amine in the pressurized stream will condense and the temperature at which the boilable component in the opposing stream will boil. This generates sufficient vaporization of the water and amine in an opposing stream 241' of amine solvent boiler 230. As said above, opposing stream 241' of amine solvent boiler 230 is lean amine from regenerator 208.

[0049] Advantageously, the thermal energy exchanged from second-stage pressurized stream 240' to opposing stream 241' is sufficient to vaporize a substantial amount of the water and amine in stream 241' to produce vaporized stream 212'. By first pressurizing stream 236', second-stage pressurized stream 240' is condensed at temperatures above the condensation temperature of the water and amine in stream 236'. As a result, the energy of condensation coupled with the temperature at which the energy is released is sufficient to vaporize at least a portion of the water and amine in stream 241'. The above description relating to the difference between the temperature at which the water and amine in the pressurized stream will condense and the temperature at which the water and amine in the opposing stream will boil also applies here.

[0050] Heat-exchanged stream 242' may proceed to an additional heat exchanger 246, which may also be referred to as amine condenser 246, for further indirect thermal energy exchange. Amine condenser 246 has an opposing input pass of water 248, such as cooling water, in a water stream 248' with the opposing output being sent to a cooling water return 250. Amine condenser 246 serves to further reduce the temperature of stream 242' in order to condense residual water and amine in stream 242' and to improve subsequent compressing efficiency. In addition to cooling water, boiler feed water, ambient air, and other thermal energy accepting fluids may be used at amine condenser 246.

[0051] After passing through amine condenser 246, second-stage further condensed stream 252' proceeds to a knock out drum 254 for separating a condensate water and amine solution stream 256' from a gaseous stream 258', which may also be referred to as a product stream 258' or an intermediary carbon dioxide product stream 258'. Product stream 258' may be suitably utilized as a product stream, such as with an enhanced oil recovery process. Liquid amine solution stream 256' may be routed back to reflux drum 234 to return the solution back to regenerator 208.

[0052] In one or more embodiments, intermediary carbon dioxide product stream 258' may be supplied to further processing, such as to remove the remaining water. In one or more embodiments, intermediary carbon dioxide product stream 258' may be further pressurized for suitable use as a product stream. Any number of additional pressurization compression stages may be utilized.

[0053] In one or more embodiments, boilers such as amine solvent boiler 219 and amine solvent boiler 230 may be utilized to generate low pressure steam. In such embodiments, the low pressure steam may be utilized to deliver heat to amine regenerator column reboiler 220 or be utilized for another useful purpose.

[0054] One or more embodiments of the invention operate in conjunction with systems that employ hydrocarbons to produce energy and also produce by-product streams. Exemplary systems employing hydrocarbons to produce energy include fuel cells and oxy-fuel combustion. Fuel cells, such as solid oxide fuel cells and molten carbonate fuel cells, convert the chemical energy within the hydrocarbon into electricity through an electrochemical reaction of the fuel with oxygen. Oxy-fuel combustion, which may also be referred to as oxicombustion, generally relates to processes that utilize high purity oxygen gas, e.g. 90% or more, as the oxidizing agent in the combustion process for combusting the hydrocarbon stream. These systems that employ a hydrocarbon to produce energy may produce an effluent or by-product stream comprised primarily of C0 2 and water vapor.

[0055] For example, as shown in Fig. 4, C0 2 recapture process 300 includes energy producing process 301, which may also be described as fuel cell process 301 or oxy-fuel combustion process 301. Energy producing process 301 includes an energy producer 302, which receives a hydrocarbon fuel stream 303 and an oxygen- containing stream 304. Energy producer 302 may be a fuel cell, furnace, boiler, combustor, gas turbine, or any other suitable system for converting hydrocarbons to energy. Hydrocarbon fuel stream 303 may include one or more suitable hydrocarbons, such as natural gas and propane. Oxygen-containing stream 304 may be air, a stream containing 90% or more oxygen gas, pure oxygen, or any other suitable oxygen-containing stream.

PROCESS OVERVIEW (HYDROCARBON STREAM TO PRODUCE ENERGY)

[0056] Energy producer 304 produces an outlet vapor phase stream 305' including steam and CO2, which may also be referred to as a mixture 305' of carbon dioxide and steam. In one or more embodiments, vapor phase stream 305' may have a composition of about 33% C0 2 by volume and the balance water vapor. In one or more embodiments, vapor phase stream 305' may have a composition of greater than 10% CO2 by volume, in other embodiments, greater than 25% CO2 by volume, and the balance water vapor. In one or more embodiments, vapor phase stream 305' may have a composition of less than 90% CO2 by volume, in other embodiments, less than 40% CO2 by volume, and the balance water vapor. In one or more embodiments, vapor phase stream 305' may include trace amounts of exhaust gases formed in the combustion of hydrocarbons.

[0057] Vapor phase stream 305' is provided to a compressor 306. Within compressor 306, outlet vapor phase stream 305' is pressurized to form a pressurized stream 308', which may also be referred to as a first-stage pressurized stream 308'. Compressor 306 may utilize any of the above-described compression ratios and inlet pressures.

[0058] Optionally, a portion of outlet vapor phase stream 305' may be provided as a flue gas recycle stream 307' back to the inlet of energy producer 302. Flue gas recycle stream 307' may be utilized to improve mixing between the hydrocarbon fuel and oxygen and to cool energy producer 302 in order to better control combustion. In one or more embodiments, from 70% to 80%, in other embodiments, from 60% to 90%, of outlet vapor phase stream 305' may be recycled as flue gas recycle stream 307'. In one or more embodiments, at least 10%, in other embodiments, at least 60%, in other embodiments, at least 70%, in other embodiments, at least 95%, of outlet vapor phase stream 305' may be recycled as flue gas recycle stream 307'. [0059] First-stage pressurized stream 308' is introduced to heat exchanger 310, which may also be described as a steam boiler 310. Within heat exchanger 310, at least a portion of the water within stream 308' is condensed at elevated pressure, and thermal energy is transferred to water contained in an opposing pass water stream 312'. The water may be provided by a water source, such as a boiler feed water make-up source 314, or by a pre-heated water stream, as will be further described herein, or a combination of pre-heated water and make-up. Opposing pass water stream 312' may also be referred to as thermal- energy accepting stream 312'.

[0060] Advantageously, the thermal energy exchanged from first-stage pressurized stream 308' to opposing pass water stream 312' is sufficient to vaporize water in stream 312' to produce a low-pressure steam stream 316'. It should be appreciated that by first pressurizing stream 305' including C0 2 and steam, water in pressurized stream 308' is condensed at temperatures above the condensation temperature of the water in stream 305'. As a result, the energy of condensation coupled with the temperature at which the energy is released is sufficient to vaporize water in stream 312'. The above description relating to the difference between the temperature at which the water in the pressurized stream will condense and the temperature at which the water in the opposing stream will boil also applies here.

[0061] In one or more embodiments, thermal energy in first-stage pressurized stream 308' may be heat exchanged with, and thereby preheat, one or more of hydrocarbon fuel stream 303, oxygen- containing stream 304, and energy producer 302 (e.g. a process side stream of energy producer 302).

[0062] After passing through heat exchanger 310, heat-exchanged stream 310' proceeds to a knock out drum 326 for separating condensed water via a condensate water stream 328'. Condensate water stream 328' exiting knock out drum 326 may be routed back to opposing pass water stream 312'.

[0063] A gaseous stream 330', which includes C0 2 and uncondensed water, and which may be referred to as a second-stage inlet stream 330', is introduced to a second- stage compressor 332, which pressurizes second-stage inlet stream 330' to form a second-stage pressurized stream 334'. [0064] Second-stage pressurized stream 334' is introduced to heat exchanger 335, which may also be described as a steam boiler 335. Within heat exchanger 335, at least a portion of the water within stream 334' is condensed at elevated pressure, and thermal energy is transferred to water contained in an opposing pass water stream 337'. The water may be provided by a water source, such as a boiler feed water make-up source 314, or by a pre-heated water stream, as will be further described herein, or a combination of pre-heated water and make-up. Opposing pass water stream 337' may also be referred to as thermal- energy accepting stream 337'.

[0065] Advantageously, the thermal energy exchanged from second-stage pressurized stream 334' to opposing pass water stream 337' is sufficient to vaporize water in stream 337' to produce a low-pressure steam stream 339'. It should be appreciated that by first pressurizing stream 330' including C0 2 and steam, water in pressurized stream 334' is condensed at temperatures above the condensation temperature of the water in stream 330'. As a result, the energy of condensation coupled with the temperature at which the energy is released is sufficient to vaporize water in stream 337'. The above description relating to the difference between the temperature at which the water in the pressurized stream will condense and the temperature at which the water in the opposing stream will boil also applies here.

[0066] Low-pressure steam stream 339' joins low-pressure steam stream 316' to form a return steam stream 341'. Steam stream 341' may be utilized wherever a low- pressure steam might be desired. In one or more embodiments, thermal energy in steam stream 341' may be heat exchanged with, and thereby preheat, one or more of hydrocarbon fuel stream 303, oxygen- containing stream 304, and energy producer 302 (e.g. a process side stream of energy producer 302).

[0067] After passing through heat exchanger 335, heat-exchanged stream 345' proceeds to an interstage cooler 318. Interstage cooler 318 serves to further reduce the temperature of stream 345' in order to condense residual water in stream 345' and to improve subsequent compressing efficiency. Interstage cooler 318 may use boiler feed water, cooling water, air, or other thermal energy accepting streams to cool stream 345'. [0068] After passing through interstage cooler 318, cooled stream 340' proceeds to a knock out drum 342 for separating condensed water via a condensate water stream 344'. Condensate water stream 344' exiting knock out drum 342 may be routed back to opposing pass water stream 312'. Condensate water stream 344' and condensate water stream 328' may be provided to a treatment system 346, such as water polishing system 346, for minor treatment to remove impurities before being used with stream 312'.

[0069] A gaseous stream 348', which includes CO2 and a minor amount of uncondensed water, and which may be referred to as product stream 348' or intermediary product stream 348', exits knock out drum 342 and may be suitably utilized as a product stream. In one or more embodiments, intermediary carbon dioxide product stream 348' may be supplied to further processing, such as to remove the remaining water. In one or more embodiments, intermediary product stream 348' may be further pressurized in additional compression stages in order to sufficiently pressurize the stream for suitable use as a product stream. Any number of additional pressurization compression stages may be utilized. An exemplary product stream is for utilization with an enhanced oil recovery process.

INDUSTRIAL APPLICABILITY

[0070] In one or more embodiments, methods of the present invention possess industrial applicability as providing thermally integrated methods for recapturing carbon dioxide.

[0071] Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not to be duly limited to the illustrative embodiments set forth herein.