Carbon dioxide removal from synthesis gas at elevated pressure

• US 8,696,797 B2
• Filed: 05/30/2008
• Issued: 04/15/2014
• Est. Priority Date: 05/30/2008
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Steele, Raymond Douglas
• Primary Examiner(s): Smith, Duane
• Assistant Examiner(s): MCKENZIE, THOMAS B
• Application Number:
  US12/130,297
• Publication Number:
  US 20090293723A1
• Time in Patent Office: 2,146 Days
• Field of Search: 423210-248, 95149-240, 95241-266, 96243-371, 96155-220, 96234-241
• US Class Current: 95/172
• CPC Class Codes: B01D 2251/80 Organic bases or salts
• CPC Class Codes: B01D 2257/308 Carbonoxysulfide COS
• CPC Class Codes: B01D 53/1425 Regeneration of liquid absorbents
• CPC Class Codes: B01D 53/1462 Removing mixtures of hydrogen sulfide and carbon dioxide
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: C10L 3/10 Working-up natural gas or synthetic natural gas
• CPC Class Codes: C10L 3/102 of acid contaminants
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A method for removing CO₂ from a pressurized gas stream with the effluent CO₂ remaining at system pressure or higher is disclosed. Specifically, the removal method provides near isothermal absorption of CO₂ from a gas stream in a suitable solvent at an elevated pressure and relatively low temperature. The solvent is then removed from contact with the gas stream, and the temperature is increased to such an extent that the CO₂ will flash from the solvent.

Claims

1. A method of removing carbon dioxide from a gas stream, the method comprising:

absorbing carbon dioxide from the gas stream using a solvent in a liquid gas contactor to form an acid gas rich-solvent, the solvent being capable of absorbing carbon dioxide at a low temperature and an inlet pressure of the gas stream into the liquid gas contactor;

introducing the acid gas rich solvent into a heating train that includes at least one flash drum coupled in reverse flow communication with at least one heat transfer apparatus and heating the acid gas rich solvent using a low pressure steam having a saturation pressure of between about 150 kPa to about 700 kPa;

flashing the heated acid gas rich-solvent to form a flash gas stream and a hot lean solvent, wherein the flash gas stream is rich in carbon dioxide;

cooling the hot lean solvent to form a cooled lean solvent;

recycling the cooled lean solvent into the liquid gas contactor;

removing at least one of water and residual solvent from the flash gas stream; and

channeling at least one of the water and the residual solvent to at least one flash drum coupled in the heating train.

2. The method as set forth in claim 1 wherein absorbing carbon dioxide from the gas stream comprises absorbing carbon dioxide from the gas stream comprising at least one of carbon dioxide, hydrogen sulfide, carbon monoxide, sulfur-containing compound, and mixtures thereof.

3. The method as set forth in claim 1 wherein absorbing carbon dioxide from the gas stream comprises absorbing the carbon dioxide using the solvent selected from an amine or an amine derivative, wherein the amine or amine derivative is selected from the group consisting of triethanolamine, methyldiethanolamine, monoethanolamine, diethanolamine, diglycolamine, diisopropanolamine, and derivatives and combinations thereof.

4. The method as set forth in claim 1 wherein absorbing carbon dioxide from the gas stream comprises absorbing the carbon dioxide in a liquid gas contactor selected from the group consisting of a trayed column, a packed column, and at least one liquid gas mixer connected to a settler.

5. The method as set forth in claim 1 further comprising channeling the heated acid rich-solvent through the at least one heat transfer apparatus via at least one pump and at least two conduits.

6. The method as set forth in claim 1 wherein heating the acid gas rich solvent using a low pressure steam comprises heating the acid gas rich solvent using a heater comprising the low pressure steam having a temperature of from about 120°

C. to about 150°

C.

7. The method as set forth in claim 1 wherein absorbing carbon dioxide comprises absorbing carbon dioxide at a temperature of from about −

20°

C. to about 35°

C. and a total pressure of from about 1000 kPa to about 15000 kPa.

8. The method as set forth in claim 1 wherein flashing the heated acid gas rich-solvent to form a flash gas stream comprises flashing at a temperature of from about 100°

C. to about 130°

C. and a total pressure of from about 1000 kPa to about 15000 kPa.

9. A method of removing carbon dioxide and hydrogen sulfide from a gas stream, the method comprising:

absorbing carbon dioxide and hydrogen sulfide from the gas stream using a solvent in a liquid gas contactor to form an acid gas rich solvent, the solvent being capable of absorbing carbon dioxide at a low temperature and an inlet pressure of the gas stream into the liquid gas contactor;

introducing the acid gas rich solvent into a heating train that includes at least one flash drum coupled in reverse flow communication with at least one heat transfer apparatus and heating the acid gas rich-solvent using a low pressure steam having a saturation pressure of between about 150 kPa to about 700 kPa;

flashing the heated acid gas rich-solvent to form a flash gas stream and a hot lean solvent, wherein the flash gas stream is rich in carbon dioxide and hydrogen sulfide;

cooling the hot lean solvent to form a cooled lean solvent; and

recycling the cooled lean solvent back into the liquid gas contactor;

removing at least one of water and residual solvent from the flash gas stream; and

channeling at least one of the water and the residual solvent to at least one flash drum coupled in the heating train.

10. The method as set forth in claim 9 wherein absorbing carbon dioxide and hydrogen sulfide from the gas stream comprises absorbing carbon dioxide and hydrogen sulfide from the gas stream comprising at least one of carbon dioxide, hydrogen sulfide, carbon monoxide, sulfur-containing compound, and mixtures thereof.

11. The method as set forth in claim 9 wherein absorbing carbon dioxide and hydrogen sulfide from the gas stream comprises absorbing the carbon dioxide and hydrogen sulfide using the solvent selected from an amine or an amine derivative, wherein the amine or amine derivative is selected from the group consisting of triethanolamine, methyldiethanolamine, monoethanolamine, diethanolamine, diglycolamine, diisopropanolamine, and derivatives and combinations thereof.

12. The method as set forth in claim 9 wherein absorbing carbon dioxide and hydrogen sulfide from the gas stream comprises absorbing the carbon dioxide and hydrogen sulfide in a liquid gas contactor selected from the group consisting of a trayed column, a packed column, and at least one liquid gas mixer connected to a settler.

13. The method as set forth in claim 9 wherein heating the acid gas rich solvent comprises heating the acid gas rich solvent using a heater to heat the low pressure steam to a temperature of between about 120°

C. to about 150°

C.

14. The method as set forth in claim 9 wherein absorbing carbon dioxide and hydrogen sulfide comprises absorbing carbon dioxide and hydrogen sulfide at a temperature of from about −

20°

C. to about 35°

C. and a total pressure of from about 1000 kPa to about 15000 kPa.

15. The method as set forth in claim 9 wherein flashing the heated acid gas rich-solvent to form a flash gas stream comprises flashing at a temperature of from about 100°

C. to about 130°

C. and a total pressure of from about 1000 kPa to about 15000 kPa.

16. The method as set forth in claim 9 wherein cooling the solvent comprises cooling the solvent to a temperature of from about 15°

C. to about 45°

C.