초록 ▼

The present invention generally relates to vacuum pressure swing adsorption (VPSA) processes and apparatus to recover carbon dioxide having a purity of approximately ≧90 mole % from streams containing at least carbon dioxide and hydrogen (e.g., syngas). The feed to the CO2 VPSA unit can be at

The present invention generally relates to vacuum pressure swing adsorption (VPSA) processes and apparatus to recover carbon dioxide having a purity of approximately ≧90 mole % from streams containing at least carbon dioxide and hydrogen (e.g., syngas). The feed to the CO2 VPSA unit can be at super ambient pressure. The CO2 VPSA unit produces three streams, a H2-enriched stream, a H2-depleted stream and a CO2 product stream. When the CO2 VPSA unit is installed between an SMR/shift reactor and a H2 PSA unit, hydrogen recovery is expected to be increased by extracting CO2, thereby increasing hydrogen partial pressure in the H2 PSA feed. The recovered CO2 can be further upgraded, sequestered or used in applications such as enhanced oil recovery (EOR).

대표청구항 ▼

What is claimed is: 1. A vacuum pressure swing adsorption (VPSA) process for the recovery of carbon dioxide from a multi-component gas mixture containing at least carbon dioxide and hydrogen in a VPSA unit containing at least one adsorption bed containing at least one CO2 -selective adsorbent, the

What is claimed is: 1. A vacuum pressure swing adsorption (VPSA) process for the recovery of carbon dioxide from a multi-component gas mixture containing at least carbon dioxide and hydrogen in a VPSA unit containing at least one adsorption bed containing at least one CO2 -selective adsorbent, the process comprising: feeding the multi-component gas mixture containing the at least carbon dioxide and the hydrogen to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream; depressurizing the at least one adsorption bed in a first depressurization step from the first pressure range to a second pressure within a second pressure range in a same direction as or in a direction opposite to the feed flow; depressurizing the at least one adsorption bed in a second depressurization step from the second pressure range to a third pressure within a third pressure range lower than the second pressure range and in a same direction as or in a direction opposite to the feed flow; depressurizing the at least one adsorption bed in a third depressurization step from the third pressure range to a predetermined pressure range (P*) in a same direction as the feed flow or in a direction opposite the feed flow to produce a hydrogen-depleted stream; depressurizing the at least one adsorption bed in a blowdown (BD) step from the P* pressure range to a pressure close to ambient pressure in a direction in a same direction or in a direction opposite as the feed flow to produce at least a first portion of CO2 product; evacuating the at least one adsorption bed from the pressure close to ambient to a pressure below ambient in a direction opposite or in a same direction as the feed flow to produce at least a second portion of CO2 product; pressure equalizing the at least one adsorption bed in a first pressure equalization step in a direction opposite or in a same direction as the feed flow; further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite or in a same direction as the feed flow; and repressurizing the at least one adsorption bed in a repressurization (RP) step to the first pressure range; wherein the process is repeated cyclically. 2. The process of claim 1, wherein the at least one adsorption bed comprises five beds. 3. The process of claim 1, wherein the first pressure range is between about 100-500 psia. 4. The process of claim 3, wherein the first pressure range is about 375 psia. 5. The process of claim 1, wherein the second pressure range is between about 80-400 psia. 6. The process of claim 1, wherein the third pressure range is between about 60-300 psia. 7. The process of claim 1, wherein P* is in the range of between about 30-130 psia. 8. The process of claim 1, wherein the first depressurization step is in a direction the same as the direction of the feed flow. 9. The process of claim 1, wherein the first depressurization step is in an opposite direction as the direction of the feed flow. 10. The process of claim 1, wherein the second depressurization step is in a direction the same as the direction of the feed flow. 11. The process of claim 1, wherein the second depressurization step is in an opposite direction as the direction of the feed flow. 12. The process of claim 1, wherein the third depressurization step is in a direction the same as the direction of the feed flow. 13. The process of claim 1, wherein the third depressurization step is in an opposite direction as the direction of the feed flow. 14. The process of claim 1, wherein the pressure range for the pressure close to ambient is about 20 psia. 15. The process of claim 1, wherein the pressure range for the pressure below ambient is 1-12 psia. 16. The process of claim 1, wherein the hydrogen-enriched stream is fed to a hydrogen recovery unit. 17. The process of claim 16, wherein the hydrogen recovery unit is a hydrogen pressure swing adsorption (PSA) unit. 18. The process of claim 1, wherein the first and second portion of the CO2 product are combined to form a final CO2 product. 19. The process of claim 1, wherein the at least one adsorption bed comprises eight beds. 20. The process of claim 19, wherein the first pressure range is between about 100-500 psia. 21. The process of claim 20, wherein the first pressure range is about 375 psia. 22. The process of claim 19, wherein the second pressure range is between about 80-400 psia. 23. The process of claim 19, wherein the third pressure range is between about 60-300 psia. 24. The process of claim 19, wherein P* is in the range of between about 30-130 psia. 25. The process of claim 24, wherein the first depressurization step is in a direction the same as the direction of the feed flow. 26. The process of claim 24, wherein the first depressurization step is in an opposite direction as the direction of the feed flow. 27. The process of claim 24, wherein the second depressurization step is in a direction the same as the direction of the feed flow. 28. The process of claim 24, wherein the second depressurization step is in an opposite direction as the direction of the feed flow. 29. The process of claim 24, wherein the third depressurization step is in a direction the same as the direction of the feed flow. 30. The process of claim 24, wherein the third depressurization step is in an opposite direction as the direction of the feed flow. 31. The process of claim 19, wherein the pressure range for the pressure close to ambient is about 20 psia. 32. The process of claim 19, wherein the pressure range for the pressure below ambient is 1-12 psia. 33. The process of claim 19, wherein the hydrogen-enriched stream is fed to a hydrogen recovery unit. 34. The process of claim 33, wherein the hydrogen recovery unit is a hydrogen pressure swing adsorption (PSA) unit. 35. The process of claim 19, wherein the first and second portion of the CO2 product are combined to form a final CO2 product. 36. A vacuum pressure swing adsorption (VPSA) process for the recovery of carbon dioxide from a multi-component gas mixture containing at least carbon dioxide and hydrogen in a VPSA unit containing at kast one adsorption bed containing at least one CO2 -selective adsorbent, the process comprising: feeding the multi-component gas mixture containing the at least carbon dioxide and the hydrogen to the at least one adsorption bed to a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream; depressurizing the at least one adsorption bed in a first depressurization step from the first pressure range to a second pressure within a second pressure range in a same direction as or in a direction opposite to the feed flow; depressurizing the at least one adsorption bed in a second depressurization step from the second pressure range to a third pressure within a third pressure range lower than the second pressure range and in a same direction as or in a direction opposite to the feed flow; depressurizing the at least one adsorption bed in a third depressurization step from the third pressure range to a fourth pressure within a fourth pressure range lower than the third pressure range and in a same direction as or in a direction opposite to the feed flow; depressurizing the at least one adsorption bed in a fourth depressurization step from the fourth pressure range to a predetermined pressure P* range in a same direction as the feed flow or in a direction opposite the feed flow to produce a hydrogen-depleted stream; depressurizing the at least one adsorption bed in a blowdown (BD) step from the P* pressure range to a pressure close to ambient pressure in a same direction as or in a direction opposite to the feed flow to produce at least a first portion of CO2 product; evacuating the at least one adsorption bed from the pressure close to ambient to a pressure below ambient in a same direction as or in a direction opposite to the feed flow to produce at least a second portion of CO2 product; pressure equalizing the at least one adsorption bed in a first pressure equalization step in a same direction as or in a direction opposite to the feed flow; further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a same direction as or in a direction opposite to the feed flow; further pressure equalizing the at least one adsorption bed in a third pressure equalization step in a same direction as or in a direction opposite to the feed flow; and repressurizing the at least one adsorption bed in a repressurization (RP) step to the first pressure range; wherein the process is repeated cyclically. 37. The process of claim 36, wherein the at least one adsorption bed comprises six beds. 38. The process of claim 36, wherein the first pressure range is between about 100-500 psia. 39. The process of claim 38, wherein the first pressure range is about 375 psia. 40. The process of claim 36, wherein the second pressure range is between about 80-400 psia. 41. The process of claim 36, wherein the third pressure range is between about 60-300 psia. 42. The process of claim 36, wherein the fourth pressure range is between about 50-200 psia. 43. The process of claim 36, wherein P* is in the range of between about 30-100 psia. 44. The process of claim 36, wherein the first depressurization step is in a direction the same as the direction of the feed flow. 45. The process of claim 36, wherein the first depressurization step is in an opposite direction as the direction of the feed flow. 46. The process of claim 36, wherein the second depressurization step is in a direction the same as the direction of the feed flow. 47. The process of claim 36, wherein the second depressurization step is in an opposite direction as the direction of the feed flow. 48. The process of claim 36, wherein the third depressurization step is in a direction the same as the direction of the feed flow. 49. The process of claim 36, wherein the third depressurization step is in an opposite direction as the direction of the feed flow. 50. The process of claim 36, wherein the fourth depressurization step is in a direction the same as the direction of the feed flow. 51. The process of claim 36, wherein the fourth depressurization step is in an opposite direction as the direction of the feed flow. 52. The process of claim 36, wherein the pressure range for the pressure close to ambient is about 20 psia. 53. The process of claim 36, wherein the pressure range for the pressure at or below ambient is 1-12 psia. 54. The process of claim 36, wherein the hydrogen-enriched stream is fed to a hydrogen recovery unit. 55. The process of claim 54, wherein the hydrogen recovery unit is a hydrogen pressure swing adsorption (PSA) unit. 56. The process of claim 36, wherein the first and second portion of the CO2 product are combined to form a final CO2 product.