Methods and systems for deacidizing gaseous mixtures

• US 7,718,151 B1
• Filed: 10/13/2008
• Issued: 05/18/2010
• Est. Priority Date: 04/07/2006
• Status: Active Grant

• Current Assignee: Liang Hu
• Original Assignee: Liang Hu
• Inventors: Hu, Liang
• Primary Examiner(s): Vanoy; Timothy C
• Application Number:
  US12/250,257
• Time in Patent Office: 582 Days
• Field of Search: 423/220, 423/226, 423/228, 423/234, 423/242.1, 423/242.2, 423/242.7, 423/243.01, 423/243.06, 423/243.08, 423/243.11, 423/243.12, 423/240.R
• US Class Current: 423/220
• CPC Class Codes: B01D 2251/306 of potassium
• CPC Class Codes: B01D 2251/606 Carbonates
• CPC Class Codes: B01D 2252/20405 Monoamines
• CPC Class Codes: B01D 2252/20421 Primary amines
• CPC Class Codes: B01D 2252/20484 with one hydroxyl group
• CPC Class Codes: B01D 2252/504 Mixtures of two or more absorbents
• CPC Class Codes: B01D 2257/2045 Hydrochloric acid
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/306 Organic sulfur compounds, e.g. mercaptans
• CPC Class Codes: B01D 2257/308 Carbonoxysulfide COS
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1418 Recovery of products
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/1493 Selection of liquid materials for use as absorbents
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

Claims

1. A method for deacidizing a gaseous mixture comprising an acid gas, the process comprising:

contacting the gaseous mixture with an absorbent in an absorption unit, wherein the absorbent comprises a carrier phase and an organic phase that is immiscible with the carrier phase;

allowing the organic phase to absorb the acid gas and convert the acid gas into an absorbed acid gas, so as to convert the absorbent into a gas-rich absorbent and to convert the gaseous mixture into a purified gaseous mixture;

allowing the absorbed acid gas to be transferred into the carrier phase, so as to form a first gas-lean phase and a gas-rich phase in the gas-rich absorbent;

providing the gas-rich absorbent to a separation unit, so as to separate the first gas-lean phase from the gas-rich phase;

cycling the separated first gas-lean phase back into the absorption unit;

providing the separated gas-rich phase to a regeneration unit, so as to obtain the acid gas and a second gas-lean phase; and

cycling the second gas-lean phase back into the absorption unit.

2. The method of claim 1, wherein the organic phase comprises a component selected from the group consisting of an alkane, an unsaturated hydrocarbon, an alcohol, a glycol, an ether, an aldehyde, a ketone, a carbohydrate, an amine, an alkanolamine, and an amino acid.

3. The method of claim 2, wherein the alcohol comprises a C₈ to C₁₂ alcohol.

4. The method of claim 1, wherein the carrier phase is hydrophilic.

5. The method of claim 1, wherein the carrier phase comprises an aqueous phase.

6. The method of claim 1, wherein the carrier phase comprises a component selected from the group consisting of an amine salt, an ammonium salt, an alkanolamine salt, an alkaline salt, an alkaline-earth salt, an amino acid salt, and water.

7. The method of claim 1, wherein the volume ratio of the carrier phase to the organic phase is about 10000:

1 to about 1;

10000.

8. The method of claim 7, wherein the volume ratio is about 50:

1 to about 1;

50.

9. The method of claim 1, wherein the gas-rich phase is regenerated by a process selected from the group consisting of thermal decomposition, gas stripping, steam stripping, distillation, treatment through a membrane contractor, pervaporization, pressure differential treatment, and a combination thereof.

10. The method of claim 1, wherein the acid gas is selected from the group consisting of CO₂, SO₂, H₂S, COS, C₂S, mercaptans, fluorides, and HCl.

11. The method of claim 10, wherein the acid gas is CO₂.

12. The method of claim 11, wherein the organic phase comprises a component selected from the group consisting of monoethanolamine, diethanolamine, piperizine, dibutylamine, and diisopropylamine, wherein the component is dissolved in at least one of a glycol, a glycol ether and a C₈-C₁₂ alcohol.

13. The method of claim 11, wherein the carrier phase comprises a component selected from the group consisting of a monoethanolamine salt, a diethanolamine salt, a piperizine salt, a dibutylamine salt, a diisopropylamine salt, a potassium bicarbonate, and a potassium carbonate.

14. The method of claim 11, wherein the absorbent comprises a pair of the organic phase and the carrier phase selected from the group consisting of:

(1) a solution of monoethanolamine in at least one of an alcohol and a glycol, a glycol ether, and one or more reaction products of monoethanolamine and CO2;

(2) a solution of monoethanolamine in at least one of an alcohol, a glycol ether and a glycol, and an aqueous solution of one or more reaction products of monoethanolamine and CO2;

(3) a solution of diethanolamine in at least one of an alcohol, a glycol ether and a glycol, and one or more reaction products of diethanolamine and CO2;

(4) a solution of diethanolamine in at least one of an alcohol, a glycol ether and a glycol, and an aqueous solution of one or more reaction products of diethanolamine and CO2;

(5) a solution of piperizine in at least one of an alcohol, a glycol ether and a glycol, and one or more reaction products of piperizine and CO2;

(6) a solution of piperizine in at least one of an alcohol, a glycol ether and a glycol, and an aqueous solution of one or more reaction products of piperizine and CO2;

(7) a solution of dibutylamine in at least one of an alcohol, a glycol ether and a glycol, and one or more reaction products of dibutylamine and CO2;

(8) a solution of dibutylamine in at least one of an alcohol, a glycol ether and a glycol, and an aqueous solution of one or more reaction products of dibutylamine and CO2;

(9) a solution of dibutylamine in at least one of an alcohol, a glycol ether and a glycol, and an aqueous solution of potassium carbonate;

(10) a solution of diisopropylamine in at least one of an alcohol, a glycol ether and a glycol, and one or more reaction products of diisopropylamine and CO2;

(11) a solution of diisopropylamine in at least one of an alcohol, a glycol ether and a glycol, and an aqueous solution of one or more reaction products of diisopropylamine and CO2; and

(12) a solution of diisopropylamine in at least one of an alcohol, a glycol ether and a glycol, and an aqueous solution of potassium carbonate.

15. The method of claim 1, wherein the organic phase absorbs the acid gas physically.

16. The method of claim 1, wherein the organic phase absorbs the acid gas chemically.

17. The method of claim 1, wherein the first gas-lean phase and the second gas-lean phase are mixed together before they are cycled back into the absorption unit.

18. The method of claim 1, wherein the gas-rich absorbent is provided to the separation unit before, after, or simultaneously with the transfer of the absorbed acid gas into the carrier phase, thus the formation of the first gas-lean phase and the gas-rich phase.

19. The method of claim 1, wherein the gas-rich absorbent moves downward from the absorption unit to the separation unit by gravity.

20. The method of claim 1, wherein the separated gas-rich phase moves downward from the separation unit to the regeneration unit by gravity.

21. The method of claim 1, wherein the gas-rich absorbent moves downward from the absorption unit to the separation unit by gravity, and the separated gas-rich phase moves downward from the separation unit to the regeneration unit by gravity.