초록

Adsorption of CO2 from flue gas streams using temperature swing adsorption. The resulting CO2 rich stream is compressed for sequestration into a subterranean formation and at least a portion of the heat of compression is used in the desorption step of the temperature swing adsorption process.

대표청구항 ▼

What is claimed is: 1. A process for the removing CO2 from a flue gas stream containing CO2, which process comprises: a) conducting said flue gas stream to a temperature swing adsorption gas separation unit wherein the gas separation unit contains at least one adsorbent contactor having a plurality

What is claimed is: 1. A process for the removing CO2 from a flue gas stream containing CO2, which process comprises: a) conducting said flue gas stream to a temperature swing adsorption gas separation unit wherein the gas separation unit contains at least one adsorbent contactor having a plurality of open flow channels through which the flue gas stream flows, wherein the surface of said flow channels are comprised of an adsorbent material that is capable of adsorbing CO2 from said flue gas stream, thereby resulting in a substantially CO2 free flue gas stream and CO2 adsorbed onto said adsorbent material; b) venting said substantially CO2 free flue gas stream into the atmosphere; c) heating said contactor having CO2 adsorbed thereon to an effective temperature that results in the desorption of at least a fraction of CO2 thereby resulting in a CO2-rich stream; d) compressing said CO2-rich stream to a pressure in excess of about 1000 psig thereby resulting in a compressed CO2-rich stream whose temperature has been substantially raised during compressing; e) cooling said compressed CO2-rich stream by use of a suitable heat-exchange fluid at a first temperature that captures heat from said CO2-rich stream thereby resulting in a CO2-rich stream of substantially reduced temperature and a heat-exchange fluid having a substantially higher second temperature; f) using at least a portion of the heat from the heat-exchange fluid of substantially higher second temperature to provide heat to the contactor during the desorption step c) above. 2. The process of claim 1 wherein a temperature swing adsorption cycle is performed at a cycle time of less than about 2 minutes between successive adsorption steps. 3. The process of claim 1 wherein at least about 75 mol % of the CO2 in the flue gas stream is removed to produce the substantially CO2 free flue gas stream. 4. The process of claim 1 wherein the adsorbent material is comprised of a zeolite. 5. The process of claim 4 wherein the zeolite is a cationic zeolite having Si/Al molar ratio of less than about 5. 6. The process of claim 1 wherein the compressing is done in multiple compression stages and cooling is done between compression stages and at the end of the last compression stage. 7. The process of the claim 6 wherein a compression stage, other than the last compression stage, ends when the CO2-rich stream reaches a temperature of about 350° C. 8. The process of claim 1 wherein heat-exchange fluid is comprised of a fluid selected from the group consisting of water and a hydrocarbon oil. 9. The process of claim 1 wherein there are multiple adsorbent contactors, each comprised of: i) a gas inlet end; and ii) a gas outlet end; wherein the gas inlet end and the gas outlet end are in fluid connection by a plurality of open flow channels wherein the surface of the open flow channels are comprised of an adsorbent material has a selectivity for CO2 over N2 of greater than 1. 10. The process of claim 9 wherein the contactor has less than about 20% of its open pore volume in pores greater than about 20 angstroms. 11. The process of claim 1 wherein the contactor is comprised of at least two adsorbent materials and the first adsorbent material has a selectively for water over CO2 of greater than 1 and is located upstream with respect to the flow of flue gas stream to a second adsorbent material that has a selectivity for CO2 over N2 of greater than 1. 12. The process of claim 11 wherein water is adsorbed from the flue gas stream in the first adsorbent material so that less than about 400 ppmv of water remains in the flue gas stream downstream of the first adsorbent material. 13. The process of claim 12 wherein water is adsorbed from the flue gas stream in the first adsorbent material so that less than about 50 ppmv of water remains in the flue gas stream downstream of the first adsorbent material. 14. The process of claim 1 wherein a first adsorbent material that has a selectivity for water over CO2 of greater than 1 is part of an adsorbent contactor that is separate from an adsorbent contactor containing the second adsorbent material that has a selectivity CO2 over N2 of greater than 1. 15. The process of claim 1 wherein the substantially CO2 rich stream contains greater than 85 mol % CO2. 16. The process of claim 11 wherein NOx, SOx or both NOx and SOx are adsorbed. 17. The process of claim 11 wherein the second adsorbent material is a cationic zeolite having a Si/Al molar ratio of less than about 5. 18. The process of claim 1 wherein the adsorbent contactor is directly heated by passing the heat exchange fluid through the same flow channels as the flue gas stream, thereby desorbing CO2 into the heat exchange fluid. 19. The process of claim 18 wherein the heat exchange fluid is passed co-current or counter-current through the flow channels compared to the direction of flow of the flue gas stream. 20. The process of claim 1 wherein a first fraction of the flow channels of the contactor are for receiving the flow of flue gas stream and a second fraction of flow channels are for receiving the flow of heat exchange fluid and wherein at least a portion of the channels of the two fractions are contiguous to each other, but not in fluid communication, so that heat flowing through said second fraction of flow channels is capable of effectively indirectly heating said first fraction of flow channels to provide heat for desorption. 21. The process of claim 20 wherein there are provided multiple contactors at least one of which is upstream to at least one other contactor wherein said at least one upstream contactor contains an adsorbent material that has a selectivity for at least one component selected for the group consisting of water, SOx, and NOx over CO2 greater than 1. 22. The process of claim 1 wherein the separation unit further comprises at least one upstream contactor has a selectivity for water over any other component in the flue gas stream of greater than 1. 23. The process of claim 1 wherein said contactor contains at least two adsorbent materials and the first adsorbent material has a selectivity for water over CO2 of greater than 1 and the second adsorbent material has a selectivity for CO2 over water of greater than 1, and wherein the first adsorbent material is located upstream, with respect to the flow of said flue gas stream, of the second adsorbent material. 24. The process of claim 1 wherein all flow channels of said contactor have substantially the same channel gap. 25. The process of claim 1 wherein the of the flue gas entering the temperature swing adsorption gas separation unit is at a temperature from about 100° C. to about 250° C. 26. The process of claim 18 wherein at least a fraction of the CO2 is separated from the heat exchange fluid after desorption thereby resulting in a second CO2 rich stream which is then compressed to a higher pressure. 27. The process of claim 1 wherein at least one contactor contains an adsorbent that is capable of removing at least 2 molecular species. 28. The process of claim 27 wherein the molecular species are water and CO2.