Method for Treating a Diamine Absorbent Stream

• US 20100108610A1
• Filed: 11/06/2008
• Published: 05/06/2010
• Est. Priority Date: 11/06/2008
• Status: Active Grant

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Cansolv Technologies Inc. (Shell Plc)
• Inventors: Campbell, Matthew, Sarlis, John, Godhwani, Vijay Bhambhani, Infantino, Melina
• Granted Patent: US 8,097,068 B2
• Time in Patent Office: Days
• US Class Current: 210/670
• CPC Class Codes: B01D 2252/2041 Diamines
• CPC Class Codes: B01D 2252/20431 Tertiary amines
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• 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 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01J 39/05 in the strongly acidic form
• CPC Class Codes: B01J 41/07 in the weakly basic form
• CPC Class Codes: B01J 49/06 containing cationic exchangers
• CPC Class Codes: B01J 49/08 containing cationic and anionic exchangers in separate beds
• CPC Class Codes: C10L 3/103 Sulfur containing contaminants
• CPC Class Codes: C10L 3/104 Carbon dioxide

Abstract

A diamine absorbent that contains heat stable salts is regenerated using an ion exchange process wherein the concentration of heat stable salts in the feed stream provided to the cation exchange unit is limited.

Claims

1. A method for treating a diamine absorbent stream comprising at least one heat stable salt, the method comprising:

a. obtaining the diamine absorbent stream from an acid gas recovery unit, the diamine absorbent stream having a concentration of heat stable salts that is less than about 1 equivalent/mole of diamine unit; and

,

b. contacting the diamine absorbent stream with an acidic cation exchange resin and generating a salt lean diamine stream and used acidic cation exchange resin,

2. The method according to claim 1, wherein the at least one heat stable salt is at least one alkali metal salt of a strong acid.

3. The method according to claim 2, wherein the strong acid comprises sulfuric acid, nitric acid or hydrochloric acid.

4. The method according to claim 2, wherein the alkali metal comprises sodium or potassium.

5. The method according to claim 1, wherein the acidic cation exchange resin is a strong acid resin.

6. The method according to claim 1, wherein the concentration of the heat stable salts is less than about 0.7 equivalents/mole of diamine.

7. The method according to claim 1, wherein the concentration of the heat stable salts is less than about 0.5 equivalents/mole of diamine.

8. The method according to claim 1, wherein the concentration of the heat stable salts is less than about 0.2 equivalents/mole of diamine.

9. The method according to claim 1, further comprising recycling the salt lean diamine stream to the acid gas recovery unit.

10. The method according to claim 1, further comprising rinsing residual diamine absorbent from the used acidic cation exchange resin with water and generating a spent wash water stream.

11. The method according to claim 10, further comprising recycling a portion of the spent wash water stream to the acid gas recovery unit.

12. The method according to claim 10, further comprising the step of regenerating the used acidic cation exchange resin with an acid and subsequently rinsing the acidic cation exchange resin with water.

13. The method according to claim 1, further comprising contacting the diamine absorbent stream with a basic anion exchange resin and generating an anion lean diamine absorbent stream and using at least a portion of the anion lean diamine absorbent stream in step (b) of claim 1.

14. The method according to claim 13, wherein the anion lean diamine absorbent stream comprises a first portion and a second portion, the first portion is used in step (b) of claim 1 and the second portion is returned to the acid gas recovery unit.

15. The method according to claim 14, wherein the first portion that is directed to the acidic cation exchange resin has a concentration of heat stable salts that is less than 0.7 equivalent/mole of diamine.

16. The method according to claim 15, wherein the concentration of heat stable salts is less than about 0.5 equivalents/mole of diamine.

17. The method according to claim 16, wherein the concentration of heat stable salts is less than about 0.2 equivalents/mole of diamine.

18. The method according to claim 13, wherein the basic anion exchange resin is a weak base resin.