Configurations and Methods for Acid Gas Absorption and Solvent Regeneration

• US 20080184887A1
• Filed: 04/18/2006
• Published: 08/07/2008
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Fluor Technologies Corporation (Fluor Corporation)
• Original Assignee: Fluor Technologies Corporation (Fluor Corporation)
• Inventors: Mak, John
• Granted Patent: US 8,398,748 B2
• Time in Patent Office: Days
• US Class Current: 95/174
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1468 Removing hydrogen sulfide
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

Contemplated configurations and methods include a solvent regenerator (58) that has an upper (93) and a lower stripping section (94). Cooled rich solve is used as reflux while heated rich solvent (11) is used as a source of stripping agent in the upper section (91). A reboiler (62) in the lower section provides further stripping agent, hi especially preferred configurations, a portion of lean solved from the regenerator (58) is further stripped in a separate or integrated regenerator (62) to form an ultra-lean solvent. Both lean and ultra-lean solvents are preferably used in a two-stage absorber (52) to thereby from the rich solvent and an offgas that is very low in acid gas.

Claims

1. A plant comprising:

a solvent regenerator having a upper section and a lower section;

wherein the upper section has a first rich solvent inlet that is configured to provide a rich solvent reflux, and a second rich solvent inlet that is configured to provide a heated rich solvent regenerator feed;

wherein the lower section is configured to produce a lean solvent from both the rich solvent reflux and the heated rich solvent regenerator feed; and

a heater operationally coupled to the regenerator and configured to heat a portion of a rich solvent to thereby provide the heated rich solvent regenerator feed.

2. The plant of claim 1 further comprising a second regenerator that is configured to receive the lean solvent from the lower section of the solvent regenerator and to produce an ultra-lean solvent from the lean solvent.

3. The plant of claim 2 further comprising an absorber having an upper section and a lower section, wherein absorber is configured to receive the ultra-lean solvent and the lean solvent in the respective upper and lower sections.

4. The plant of claim 3 further comprising a flash vessel coupled to the absorber and configured to flash the rich solvent from the absorber.

5. The plant of claim 1 further comprising a heat exchanger that is configured to heat untreated gas prior to entry into the absorber to thereby cool the rich solvent reflux.

6. The plant of claim 1 wherein the lean solvent comprises an amine-based solvent.

7. A method of regenerating a solvent, comprising:

feeding a first portion of a rich solvent as reflux to a first section of a regenerator, and feeding a heated second portion of the rich solvent to the first section of the regenerator;

wherein the second portion has a temperature sufficient to provide at least a portion of striping medium to the first section; and

forming in a second section of the regenerator a lean solvent from the first ad second portions to thereby regenerate the solvent.

8. The method of claim 7 wherein a heat exchanger hears the second portion of the rich solvent using heat from a bottom product of the regenerator.

9. The method of claim 7 further comprising a step of cooling the first portion of the rich solvent prior to the step of feeding the first portion to the first section of the regenerator.

10. The method of claim 7 further comprising a step of feeding at least a portion a bottom product of the regenerator to a second regenerator to thereby form an ultra-lean solvent.

11. The method of claim 10 further comprising a step of coupling an absorber to the regenerator, wherein the absorber produces the rich solvent.

12. The method of claim 11 wherein the absorber has an upper section and a lower section, and wherein the ultra-lean solvent and the lean solvent are fed to the respective upper and lower sections of the absorber.

13. The method of claim 11 further comprising a step of flashing the rich solvent before the rich solvent is divided in a first and second portion.

14. The method of claim 11 further comprising a step of heating untreated gas in a heat exchanger prior to entry into the absorber to thereby cool the first portion of the rich solvent.

15. The method of claim 11 wherein the absorber produces an absorber overhead product, and wherein the absorber overhead product is combined with a portion of the ultra-lean solvent to produce a semi-lean solvent.

16. The method of claim 15 further comprising a step of feeding the semi-lean solvent as a reflux stream to the upper section of the regenerator.

17. A plant comprising:

a two-stage absorber that has an upper section aid a lower section, wherein the absorber is configured to produce a rich solvent;

a flow control element fluidly coupled to the absorber and configured to split the rich solvent from the absorber into a first and a second portion;

a heater coupled to a conduit that is configured to receive the second portion of the rich solvent and wherein the heater is configured to heat the second portion of the rich solvent;

a regenerator that has an upper section and a lower section, wherein the regenerator is configured to produce a lean solvent from the first and second portions of the rich solvent;

a first and second conduit fluidly coupled to the flow control element such that

(a) the first conduit feeds the first portion of the rich solvent to the upper section of the regenerator as reflux; and

(b) the second conduit feeds the heated second portion of the rich solvent to the upper section of the regenerator as regenerator feed.

18. The plant of claim 17 wherein the heater is a heat exchanger that is configured to use heat of the lean solvent for the heating the first portion of the rich solvent.

19. The plant of claim 17 further comprising a heat exchanger that is configured to heat untreated gas before entry into the absorber using heat from the second portion of the rich solvent.

20. The plant of claim 17 further comprising a flash vessel that receives the rich solvent, and wherein the flash vessel is coupled to the absorber in a position upstream of the first and second conduits.

21. A plant comprising:

a solvent regenerator having a upper section, an intermediate section, and a lower section, and wherein a chimney tray is disposed between the intermediate section and the lower section;

wherein the upper section has a first rich solvent inlet that is configured to provide a rich solvent reflux, and further has a second rich solvent inlet that is configured to provide a heated rich solvent regenerator feed;

wherein the intermediate section is configured to produce a lean solvent from the rich solvent reflux and the heated rich solvent regenerator feed;

wherein the lower section is configured to form an ultra lean solvent from the lean solvent; and

a heater operationally coupled to the regenerator and configured to heat a portion of a rich solvent to thereby provide the heated rich solvent regenerator feed.

22. The plant of claim 21 further comprising a side reboiler that is configured to reboil a portion of the lean solvent.

23. The plant of claim 21 wherein the lean solvent has a hydrogen sulfide to amine loading ratio of at least 0.01, and wherein the ultra lean solvent has a hydrogen sulfide to amine loading ratio of no more than 0.01.