Process for the removal of heat stable salts from acid gas absorbents

• US 10,118,123 B2
• Filed: 03/17/2011
• Issued: 11/06/2018
• Est. Priority Date: 03/17/2010
• Status: Expired due to Fees

• Current Assignee: Shell Oil Company (Shell Plc)
• Original Assignee: Shell Oil Company (Shell Plc)
• Inventors: Bhambhani Godhwani, Vijay, Sarlis, John Nicholas
• Primary Examiner(s): Diggs, Tanisha
• Application Number:
  US13/634,569
• Publication Number:
  US 20130193375A1
• Time in Patent Office: 2,791 Days
• Field of Search: None
• CPC Class Codes: B01D 2251/21 Organic compounds not provided for in groups B01D2251/206 or B01D2251/208
• CPC Class Codes: B01D 2251/30 Alkali metal compounds
• CPC Class Codes: B01D 2251/304 of sodium
• CPC Class Codes: B01D 2251/40 Alkaline earth metal or magnesium compounds
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01J 20/20 comprising free carbon; comprising carbon obtained by carbonising processes
• CPC Class Codes: B01J 39/08 Use of material as cation exchangers; Treatment of material for improving the cation exchange properties

Abstract

A process for the regeneration of an acid gas absorbent comprising an amine and heat stable salts by phase separation, comprising a) mixing the acid gas absorbent with an alkaline solution, to form a mixture with a pH above the pH equivalence point of the amine; b) cooling the mixture to a temperature below 500 C; c) separating the mixture into a regenerated acid gas absorbent and a waste stream; d) collecting the regenerated acid gas absorbent separate from the waste stream.

Claims

1. A process for the regeneration of an acid gas absorbent comprising an amine and heat stable salts by phase separation, comprising:

a) mixing the acid gas absorbent with an alkaline solution, to form a mixture with a pH above the pH equivalence point of the amine, wherein the acid gas absorbent comprises in the range of from 15 up to 40 wt % of amine based on the total weight of the acid gas absorbent;

b) cooling the mixture to a temperature below 50°

C.;

c) separating the mixture into a regenerated acid gas absorbent and a waste stream; and

d) collecting the regenerated acid gas absorbent separated from the waste stream.

2. A process according to claim 1, wherein step c) is performed by leaving the mixture undisturbed for at least 30 minutes to allow separation of the regenerated acid gas absorbent and the waste stream.

3. A process according to claim 1, wherein the acid gas absorbent is an aqueous amine solvent.

4. A process according to claim 1, wherein the acid gas absorbent comprises in the range of from 10 to 25 wt % of sulfate based on the total weight of the acid gas absorbent.

5. A process according to claim 1, wherein the acid gas absorbent comprises in the range of from 13 up to 16 wt % of sulfate, in the range of from 23 up to 27 wt % of the amine and in the range of from 57 up to 64 wt % of water, in such amounts that the total equals 100 wt %.

6. A process according to claim 1, wherein the alkaline solution comprises a Group I or a Group II hydroxide.

7. A process according to claim 1, wherein the mixture has a pH in the range of from 10 to 13.

8. A process according to claim 1, wherein mixing takes place in a stirred tank reactor.

9. A process according to claim 8, wherein the stirred tank reactor furthermore comprises a recirculation loop.

10. A process according to claim 1, wherein the mixture is cooled to a temperature in the range of from 20 to 45°

C.

11. A process according to claim 1, wherein a top layer comprises the regenerated acid gas absorbent and a bottom layer comprises the waste stream.

12. A process according to claim 6, wherein the regenerated acid gas absorbent is further treated according to the following step:

e) treating the regenerated acid gas absorbent via cationic ion exchange to remove a Group I or Group II metal compound present in the regenerated absorbent.

13. A process according to claim 12, wherein the regenerated acid gas absorbent is further treated according to the following step:

f) treating the regenerated acid gas absorbent with activated carbon to remove at least hydrocarbons.

14. A process according to claim 13, wherein the regenerated acid gas absorbent is further treated according to the following step:

g) passing the regenerated acid gas absorbent through a filtration and/or microfiltration unit.