Heat integration for hot solvent stripping loop in an acid gas removal process

• US 7,785,399 B2
• Filed: 01/16/2009
• Issued: 08/31/2010
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: UOP Llc (Honeywell International Inc.)
• Original Assignee: UOP Llc (Honeywell International Inc.)
• Inventors: Davis, Lamar A., Lechnick, William J., Zhu, Xin, Huang, Richard
• Primary Examiner(s): Hill, Jr.; Robert J
• Assistant Examiner(s): Jones; Christopher P
• Application Number:
  US12/354,949
• Publication Number:
  US 20100132554A1
• Time in Patent Office: 592 Days
• Field of Search: 951/86, 951/87, 951/91, 951/94, 952/27, 423/226, 423/228, 423/229
• US Class Current: 95/114
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/308 Carbonoxysulfide COS
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1456 Removing acid components
• CPC Class Codes: B01D 53/343 Heat recovery
• CPC Class Codes: B01D 53/77 Liquid phase processes
• CPC Class Codes: B01D 53/78 with gas-liquid contact

Abstract

Systems and processes utilize one or more methods of providing overhead waste process heat to increase the feed temperature of the hot solvent stripping regeneration loop in an acid gas removal process. A heated rich solvent stream can be the primary feed for the hot solvent stripping regeneration loop, and one or more slip streams can be heated and then combined with the heated rich solvent stream to form a combined rich solvent stream prior to further processing in downstream units to remove acid gas from the solvent. A first slip stream can be heated in a stripper gas heat exchanger by heat exchange with a stripped gas stream. A second slip stream can be heated in a regenerator exchanger by heat exchange with an acid gas stream. A third slip stream can be heated in a recycle gas exchanger by heat exchange with a compressed recycle gas stream.

Claims

1. An acid gas removal process comprising the steps of:

providing a feed gas including acid gas to at least one absorber, the at least one absorber including an absorbent material that absorbs acid gas;

removing acid gas from the feed gas by absorption to produce a first rich solvent stream including solvent and acid gas;

separating at least one slip stream from the first rich solvent stream and heating the at least one slip stream by heat exchange to produce at least one heated slip stream;

passing at least a portion of the first rich solvent stream to a bridge heat exchanger to produce a heated rich solvent stream;

combining the at least one heated slip stream with the heated rich solvent stream to form a combined rich solvent stream before any stripping; and

passing the combined rich solvent stream to a concentrator to produce a stripped solvent stream as a bottoms stream, and a stripped gas stream as an overhead stream.

2. The acid gas removal process of claim 1, wherein the at least one slip stream comprises a first slip stream that is heated in a stripper gas heat exchanger by heat exchange with the stripped gas stream to produce a heated first slip stream.

3. The acid gas removal process of claim 2, wherein the first slip stream is from about 5% by weight to about 20% by weight of the rich solvent stream.

4. The acid gas removal process of claim 2, wherein the first slip stream has a solvent mass quantity that is substantially equal to a solvent mass quantity of the stripped gas stream.

5. The acid gas removal process of claim 2, wherein a second slip stream has a solvent mass quantity that is substantially equal to a solvent mass quantity of the acid gas stream.

6. The acid gas removal process of claim 1, further comprising:

passing the stripped solvent stream to a regenerator to remove acid gas and produce an acid gas stream as an overhead stream, and a lean solvent stream as a bottoms stream.

7. The acid gas removal process of claim 6, wherein the at least one slip stream comprises a slip stream that is heated in a regenerator exchanger by heat exchange with the acid gas stream to produce a heated slip stream.

8. The acid gas removal process of claim 7, wherein the slip stream is from about 5% by weight to about 20% by weight of the rich solvent stream.

9. The acid gas removal process of claim 1, further comprising:

passing the stripped gas stream to a separator to produce a recycle gas stream as an overhead stream; and

passing the recycle gas stream to one or more compressors to produce compressed recycle gas stream.

10. The acid gas removal process of claim 9, wherein the at least one slip stream comprises a slip stream that is heated in a recycle gas exchanger by heat exchange with the compressed recycle gas stream to produce a heated slip stream.

11. The acid gas removal process of claim 10, wherein the slip stream is from about 5% by weight to about 20% by weight of the rich solvent stream.

12. The acid gas removal process of claim 10, wherein the slip stream has a solvent mass quantity that is substantially equal to a solvent mass quantity of the compressed recycle gas stream.

13. An acid gas removal process comprising the steps of:

providing a feed gas including acid gas to at least one absorber, the at least one absorber including an absorbent material that absorbs acid gas;

removing acid gas from the feed gas by absorption to produce a first rich solvent stream including solvent and acid gas;

separating at least one slip stream from the first rich solvent stream and heating the at least one slip stream by heat exchange to produce at least one heated slip stream;

passing at least a portion of the first rich solvent stream to a bridge heat exchanger to produce a heated rich solvent stream;

combining the at least one heated slip stream with the heated rich solvent stream to form a combined rich solvent stream before any stripping;

passing the combined rich solvent stream to a concentrator to produce a stripped solvent stream as a bottoms stream, and a stripped gas stream as an overhead stream;

passing the stripped solvent stream to a regenerator to remove acid gas and produce an acid gas stream as an overhead stream, and a lean solvent stream as a bottoms stream;

passing the stripped gas stream to a separator to produce a recycle gas stream as an overhead stream; and

passing the recycle gas stream to one or more compressors to produce compressed recycle gas stream.

14. The acid gas removal process of claim 13, wherein the at least one slip stream comprises a first slip stream that is heated in a stripper gas heat exchanger by heat exchange with the stripped gas stream to produce a heated first slip stream.

15. The acid gas removal process of claim 13, wherein the at least one slip stream comprises a slip stream that is heated in a regenerator exchanger by heat exchange with the acid gas stream to produce a heated slip stream.

16. The acid gas removal process of claim 13, wherein the at least one slip stream comprises a slip stream that is heated in a recycle gas exchanger by heat exchange with the compressed recycle gas stream to produce a heated slip stream.

17. The acid gas removal process of claim 13, wherein the at least one slip stream comprises:

a first slip stream that is heated in a stripper gas heat exchanger by heat exchange with the stripped gas stream to produce a heated first slip stream; and

at least one of a slip stream that is heated in a regenerator exchanger by heat exchange with the acid gas stream to produce another heated slip stream, or a slip stream that is heated in a recycle gas exchanger by heat exchange with the compressed recycle gas stream to produce a further heated slip stream.

18. An acid gas removal process comprising the steps of:

providing a feed gas including acid gas to at least one absorber, the at least one absorber including an absorbent material that absorbs acid gas;

removing acid gas from the feed gas by absorption to produce a first rich solvent stream including solvent and acid gas;

separating a first slip stream from the first rich solvent stream and heating the first slip stream in a stripper gas heat exchanger by heat exchange with the stripped gas stream to produce a heated first slip stream;

passing at least a portion of the first rich solvent stream to a bridge heat exchanger to produce a heated rich solvent stream; and

combining the first heated slip stream with the heated rich solvent stream to form a combined rich solvent stream before any stripping.

19. The process of claim 18, further comprising:

passing the combined rich solvent stream to a concentrator to produce a stripped solvent stream as a bottoms stream, and a stripped gas stream as an overhead stream;

passing the stripped solvent stream to a regenerator to remove acid gas and produce an acid gas stream as an overhead stream, and a lean solvent stream as a bottoms stream; and

separating a second slip stream from the first rich solvent stream that is heated in a regenerator exchanger by heat exchange with the acid gas stream to produce a heated second slip stream.

20. The process of claim 18, further comprising:

passing the combined rich solvent stream to a concentrator to produce a stripped solvent stream as a bottoms stream, and a stripped gas stream as an overhead stream;

passing the stripped solvent stream to a regenerator to remove acid gas and produce an acid gas stream as an overhead stream, and a lean solvent stream as a bottoms stream;

passing the stripped gas stream to a separator to produce a recycle gas stream as an overhead stream;

passing the recycle gas stream to one or more compressors to produce compressed recycle gas stream; and

separating a slip stream from the first rich solvent stream that is heated in a recycle gas exchanger by heat exchange with the compressed recycle gas stream to produce a further heated slip stream.