Configurations and method for improved gas removal

• US 20050000360A1
• Filed: 04/15/2002
• Published: 01/06/2005
• Est. Priority Date: 04/15/2002
• Status: Active Grant

• Current Assignee: Fluor Enterprises Incorporated (Fluor Corporation)
• Original Assignee: Fluor Enterprises Incorporated (Fluor Corporation)
• Inventors: Mak, John, Graham, Curt, Nielsen, Richard
• Granted Patent: US 7,192,468 B2
• Time in Patent Office: Days
• US Class Current: 95/236
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: C10L 3/10 Working-up natural gas or synthetic natural gas
• CPC Class Codes: C10L 3/102 of acid contaminants
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A plant includes an absorber (103) that operates in a gas phase supercritical region and removes an acid gas from a feed stream (9) at high recovery of the feed stream (10) while producing a high purity acid gas stream (36). Particularly preferred plants include gas purification plants that receive a feed gas with at least 5 mol % carbon dioxide at a pressure of at least 3000 psi.

Claims

1. A plant comprising an absorber that operates in a gas phase supercritical region and receiving a dehydrated feed gas comprising at least 5 mol % carbon dioxide, wherein a physical solvent absorbs at least part of the carbon dioxide in the absorber to form a carbon dioxide stream containing at least 95 mol % carbon dioxide.

2. The plant of claim 1 wherein the feed gas is cooled to a temperature above a hydrate point of the feed gas and wherein the cooled feed gas is dehydrated in a dehydration unit before entering the absorber.

3. The plant of claim 1 wherein the feed gas has a pressure of at least 3000 psi.

4. The plant of claim 1 wherein the feed gas comprises natural gas.

5. The plant of claim 1 wherein the physical solvent comprises propylene carbonate.

6. The plant of claim 1 wherein the absorber forms a rich solvent that is depressurized, thereby providing cooling of the carbon dioxide stream and further providing a first hydrocarbon recycle stream that is fed into the absorber.

7. The plant of claim 6 wherein the depressurized rich solvent is further depressurized, thereby providing cooling of the solvent in the absorber and further providing a second hydrocarbon recycle stream that is fed into the absorber.

8. The plant of claim 7 wherein the further depressurized rich solvent is let down and separated in a separator to form a lean solvent and the carbon dioxide stream.

9. The plant of claim 7 wherein a compressor compresses the first and second hydrocarbon recycle stream and wherein the compressed first and second hydrocarbon recycle streams are combined with the dehydrated feed gas.

10. The plant of claim 8 wherein the lean solvent is treated in a vacuum separator using lean gas thereby regenerating the physical solvent for the absorber and further generating a fuel gas.

11. The plant of claim 2 wherein the absorber produces a product gas, and wherein the feed gas is cooled by the product gas.

12. The plant of claim 11 wherein the feed gas comprises natural gas, and wherein the product gas comprises at least 99% of the natural gas.

13. The plant of claim 1 wherein the carbon dioxide stream is employed in an enhanced oil recovery.

14. A plant comprising:

an absorber that receives a feed gas at a pressure of at least 1000 psi and comprising at least 5 mol % carbon dioxide, wherein the absorber employs a physical solvent to produce a rich solvent and a product gas that is at least partially depleted from the carbon dioxide;

a first turbine that depressurizes the rich solvent and a first separator that separates a first hydrocarbon portion from the depressurized rich solvent, thereby producing a first hydrocarbon recycle stream and a first rich solvent;

a second turbine that further depressurizes the first rich solvent and a cooler that employs the further depressurized first solvent to cool the physical solvent to maintain a bottom temperature of the absorber in a desired temperature range; and

wherein the further depressurized first solvent is separated in a second separator that separates a second hydrocarbon portion from the further depressurized first solvent, thereby producing a second hydrocarbon recycle stream and a second rich solvent, and wherein the first and second hydrocarbon recycle streams are fed into the absorber.

15. The plant of claim 14 wherein the feed gas is at least partially dehydrated.

16. The plant of claim 15 wherein he feed gas is cooled by the product gas and dehydrated in a dehydration unit before entering the absorber.

17. The plant of claim 14 wherein the first rich solvent is employed as a refrigerant to cool a carbon dioxide stream.

18. The plant of claim 14 wherein the second rich solvent is further depressurized to remove at least part of the carbon dioxide, thereby forming a lean solvent.

19. The plant of claim 18 wherein the lean solvent is further processed in a vacuum separator that employs a lean gas and produces a fuel gas, thereby regenerating the physical solvent.

20. The plant of claim 18 wherein the physical solvent comprises propylene carbonate.

21. The plant of claim 18 wherein the carbon dioxide is employed in an enhanced oil recovery.

22. The plan of claim 14 further comprising a stripper having at least two stripping sections separated by a collecting tray, and wherein the stripper regenerates the physical solvent

23. A method of operating a plant, comprising;

providing an absorber that receives a feed gas at a pressure of at least 1000 psi wherein the feed gas comprises an acid gas;

removing at least pan of the acid gas from the feed gas using a physical solvent, thereby forming a product gas and a rich solvent;

reducing pressure of the rich solvent to form a hydrocarbon recycle stream that is fed into the absorber, thereby producing a depressurized rich solvent;

using the depressurized rich solvent to cool the physical solvent, thereby maintaining a bottom temperature of the absorber in a desired temperature range and forming a heated depressurized rich solvent; and

separating the heated depressurized rich solvent into a stream containing at least a portion of the acid gas, thereby forming a lean solvent.

24. The method of claim 23 wherein the fed gas has a pressure of between about 3000 psi and about 5000 psi.

25. The method of claim 23 wherein the acid gas is carbon dioxide.

26. The method of claim 23 wherein the physical solvent comprises propylene carbonate.