Gas treatment process and system

• US 8,329,128 B2
• Filed: 02/01/2011
• Issued: 12/11/2012
• Est. Priority Date: 02/01/2011
• Status: Active Grant

• Current Assignee: General Electric Technology GmbH (GE Vernova, Inc.)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Dube, Sanjay Kumar, Muraskin, David James
• Primary Examiner(s): VANOY, TIMOTHY C
• Application Number:
  US13/018,456
• Publication Number:
  US 20120195816A1
• Time in Patent Office: 679 Days
• Field of Search: 423/220, 423/243.06, 423/DIG.6, 422/168, 422/169, 422/170, 422/171, 422/172
• US Class Current: 423/220
• CPC Class Codes: B01D 2251/2062 Ammonia
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/304 Hydrogen sulfide
• CPC Class Codes: B01D 2257/406 Ammonia
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 53/1406 Multiple stage absorption
• CPC Class Codes: B01D 53/1475 Removing carbon dioxide
• CPC Class Codes: B01D 53/1481 Removing sulfur dioxide or sulfur trioxide
• CPC Class Codes: B01D 53/343 Heat recovery
• CPC Class Codes: B01D 53/501 by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
• CPC Class Codes: B01D 53/58 Ammonia
• CPC Class Codes: B01D 53/62 Carbon oxides
• CPC Class Codes: B01D 53/75 Multi-step processes
• CPC Class Codes: Y02A 50/20 Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A gas stream containing carbon dioxide and sulfur dioxide is cleaned by removing, in a sulfur removal stage, sulfur dioxide from the gas stream. Sulfur dioxide is removed from the gas stream by bringing the gas stream into direct contact with ammonia. The used ammonia may be recycled.

In a carbon dioxide removal stage, carbon dioxide is removed from the gas stream depleted in sulfur dioxide by bringing the gas stream into contact with an ammoniated liquid. Following sulfur dioxide and carbon dioxide removal, in an ammonia removal stage, ammonia from the gas stream is removed. Ammonia is removed from the gas stream by bringing the gas stream into direct contact with an acidic liquid to absorb into the acidic liquid, ammonia from the gas stream. The used acidic liquid may be recycled.

Claims

1. A process for cleaning a gas stream containing carbon dioxide and sulfur dioxide, including removal of carbon dioxide from the gas stream in a carbon dioxide removal stage;

the process comprising

a) removing, in a sulfur removal stage, sulfur dioxide from the gas stream by bringing the gas stream into direct contact with a liquid comprising ammonia, to absorb into the liquid sulfur dioxide from the gas stream such that the gas stream is depleted in sulfur dioxide;

b) cooling, in a gas cooling stage, the gas stream such that a cooled gas stream is formed;

c) removing, in the carbon dioxide removal stage, carbon dioxide from the cooled gas stream depleted in sulfur dioxide by bringing the gas stream into contact with ammoniated liquid to absorb into the liquid carbon dioxide from the gas stream such that the gas stream is depleted in carbon dioxide and enriched in ammonia;

d) removing, in an ammonia removal stage, ammonia from the gas stream depleted in carbon dioxide by bringing the gas stream into direct contact with an acidic liquid, to absorb into the acidic liquid ammonia from the gas stream such that the gas stream is depleted in ammonia; and

e) heating, in a gas heating stage, the gas stream depleted in ammonia such that a heated gas stream is formed;

wherein at least a portion of the used liquid from stage a) is withdrawn and directed for reuse in stage a), and at least a portion of the used liquid from stage d) is withdrawn and directed for reuse in stage d).

2. The process of claim 1, wherein stage a) is performed before stage b).

3. The process of claim 1, wherein stage b) is performed before stage a).

4. The process of claim 1, wherein

the cooling stage b) comprises

cooling, in a gas cooling step, the gas stream by bringing it into contact with a cooling liquid to allow transfer of heat from the gas to the cooling liquid and to condense water from the gas, such that the gas stream is cooled and the liquid is heated;

and

the heating stage e) comprises

heating, in a gas heating step, the gas stream depleted in ammonia from stage d) by bringing the gas stream into contact with a heating liquid to allow transfer of heat from the liquid to the gas, such that the gas stream is heated and the liquid is cooled; and

the gas cooling step and the gas heating step are in liquid connection such that heat energy of the heated liquid from the gas cooling step is transferred to the cooled liquid from the gas heating step to form a heated liquid for use in the gas heating step and a cooled liquid for use in the gas cooling step.

5. The process of claim 4, wherein the heated liquid from the gas cooling step is subjected to heat-exchanging with the cooled liquid from the gas heating step, to heat the cooled liquid from the gas heating step prior to reuse in the gas heating step and to cool the heated liquid from the gas cooling step prior to reuse in the gas cooling step.

6. The process of claim 4, wherein the gas cooling step and the gas heating step are in liquid connection such that at least a portion of the heated liquid from the gas cooling step is withdrawn and directed for use as a heating liquid in the gas heating step, and at least a portion of the cooled liquid from the gas heating step is withdrawn and directed for use in the gas cooling step as the cooling liquid.

7. The process of claim 6, further comprising

cooling, in a liquid cooling step, the cooled liquid from the gas heating step by bringing the cooled liquid into contact with the acidic liquid from the ammonia removal stage, prior to directing the cooled liquid for use in the gas cooling step and the acidic liquid for reuse in the ammonia removal stage, to allow transfer of heat from the cooled liquid to the acidic liquid, such that the cooled liquid is further cooled and the acidic liquid is heated.

8. The process of claim 4, wherein

the cooling stage b) further comprises

cooling, in a second gas cooling step, the gas stream from the gas cooling step of claim 4 by bringing the gas stream into contact with a second cooling liquid to allow transfer of heat from the gas to the cooling liquid and to condense water from the gas, such that the gas stream is cooled and the liquid is heated.

9. The process of claim 8, further comprising

cooling, in a second liquid cooling step, the heated liquid from the second gas cooling step by subjecting the heated liquid to heat-exchanging with a cooling medium, such that a cooled liquid is formed;

and

directing the cooled liquid for reuse as the second cooling liquid in the second gas cooling step.

10. The process of claim 1, wherein the pH-value of the liquid comprising ammonia utilized for sulfur removal is controlled to be in the range of between 4 and 6.

11. The process of claim 1, wherein the pH-value of the acidic liquid utilized for ammonia removal is controlled to be below 4.

12. The process of claim 11, wherein the pH-value of the acidic liquid is controlled by addition of sulfuric acid.

13. A gas cleaning system for cleaning a gas stream containing carbon dioxide and sulfur dioxide, including a carbon dioxide removal arrangement, the system comprising

a sulfur removal device arranged upstream of the carbon dioxide removal arrangement, with respect to the flow direction of the gas stream, configured to receive and to bring the gas stream into contact with a liquid comprising ammonia, to form and to discharge a gas stream depleted in sulfur dioxide;

a gas cooling arrangement arranged upstream of the carbon dioxide removal arrangement, with respect to the flow direction of the gas stream, configured to receive and to cool the gas stream, and to discharge a cooled gas stream;

a carbon dioxide removal arrangement comprising at least one carbon dioxide absorber configured to receive the cooled gas stream depleted in sulfur dioxide and to bring the gas stream into contact with ammoniated liquid, to form and to discharge a gas stream depleted in carbon dioxide and enriched in ammonia;

an ammonia removal device arranged downstream of the carbon dioxide removal arrangement, with respect to the flow direction of the gas stream, configured to receive the gas stream from the carbon dioxide removal arrangement and to bring the gas stream into contact with an acidic liquid to form and to discharge a gas stream depleted in ammonia; and

a gas heating arrangement arranged downstream of the carbon dioxide removal arrangement, with respect to the flow direction of the gas stream, configured to receive the gas stream depleted in ammonia, to heat the gas stream and to discharge a heated gas stream;

wherein the sulfur removal device is configured to receive and reuse at least a portion of the used liquid discharged from the sulfur removal device, and the ammonia removal device is configured to receive and reuse at least a portion of the used liquid discharged from the ammonia removal device.

14. The system of claim 13, wherein the gas cooling arrangement is arranged downstream of the sulfur removal device, with respect to the flow direction of the gas stream, and is configured to receive the gas stream depleted in sulfur dioxide from the sulfur removal device.

15. The system of claim 13, wherein the sulfur removal device is arranged downstream of the gas cooling arrangement, with respect to the flow direction of the gas stream, and is configured to receive the cooled gas stream from the gas cooling arrangement.

16. The system of claim 13, wherein

the gas cooling arrangement comprises a gas cooling device, configured to receive the gas stream and to bring the gas stream into contact with a cooling liquid, to form and to discharge a cooled gas stream and a heated liquid;

and

the gas heating arrangement comprises a gas heating device configured to receive the gas stream depleted in ammonia discharged from the ammonia removal device and to bring the gas stream into contact with a heating liquid, to form and to discharge a heated gas stream and a cooled liquid.

17. The system of claim 16, comprising a heat-exchanger, configured to receive the cooled liquid from the gas heating device and to bring it into contact with the heated liquid from the gas cooling device, to form and discharge a heated heating liquid for reuse in the gas heating device and a cooled cooling liquid for reuse in the gas cooling device.

18. The system of claim 16, wherein the gas heating device is configured to receive at least a portion of the heated liquid discharged from the gas cooling device for use as the heating liquid, and the gas cooling device is configured to receive at least a portion of the cooled liquid discharged from the gas heating device for use as the cooling liquid.

19. The system of claim 18, comprising a heat-exchanger configured to receive the cooled heating liquid from the gas heating device and to bring it into contact with the acidic liquid from the ammonia removal device, to form and to discharge a cooled cooling liquid for use in the gas cooling device and a heated acidic liquid for reuse in the ammonia removal device.

20. The system of claim 16, wherein the gas cooling arrangement further comprises

a second gas cooling device configured to receive the gas stream discharged from the gas cooling device of claim 16 and to bring the gas stream into contact with a second cooling liquid, to form and to discharge a cooled gas stream and a heated liquid.

21. The system of claim 20, further comprising

a liquid cooling device configured to receive at least a portion of the heated liquid discharged from the second gas cooling device and to bring the heated liquid into contact with a cooling medium, to form and to discharge a cooled liquid;

wherein the second gas cooling device is configured to receive at least a portion of the cooled liquid discharged from the liquid cooling device for use as the second cooling liquid.