GAS TURBINE COMBINED CYCLE OPTIMIZED FOR POST-COMBUSTION CO2 CAPTURE

• US 20170268425A1
• Filed: 04/29/2016
• Published: 09/21/2017
• Est. Priority Date: 03/15/2016
• Status: Active Grant

• Current Assignee: Bechtel Power Corporation (Bechtel Group Incorporated)
• Original Assignee: Bechtel Power Corporation (Bechtel Group Incorporated)
• Inventors: Gulen, Seyfettin Can
• Granted Patent: US 10,641,173 B2
• Time in Patent Office: Days
• CPC Class Codes: F01K 23/103 with afterburner in exhaust boiler
• CPC Class Codes: F01K 3/20 with heating by combustion gases of main boiler
• CPC Class Codes: F02C 3/34 with recycling of part of the working fluid, i.e. semi-closed cycles with combustion products in the closed part of the cycle
• CPC Class Codes: F02C 7/10 by means of regenerative heat-exchangers
• CPC Class Codes: F05D 2260/611 Sequestration of CO2
• CPC Class Codes: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
• CPC Class Codes: Y02E 20/32 Direct CO2 mitigation

Abstract

In a gas turbine system including a first gas turbine generator, a heat recovery steam generator and a steam turbine generator heat rejection system, the present invention relates to a method for CO₂ capture from flue gas in said system, said method including: (a) diverting an amount of heat recovery steam generator flue gas from the CO₂ capture plant; and (b) mixing the diverted heat recovery steam generator flue gas with an air stream, forming a combined gas stream, wherein (1) the combined gas stream is fed to a second gas turbine generator; (2) exhaust gas from the second gas turbine generator is mixed with exhaust gas from the first gas turbine generator, forming a combined exhaust gas stream; and (3) the combined exhaust gas stream enters the heat recovery steam generator, with the CO₂ content of the combined exhaust gas stream increased through supplementary firing in the heat recovery steam generator.

Claims

1. In a gas turbine system including a first gas turbine generator, a heat recovery steam generator and a steam turbine generator heat rejection system, a method for CO₂ capture from flue gas in said system, comprising:

diverting an amount of heat recovery steam generator flue gas from a CO₂ capture plant; and

mixing the diverted heat recovery steam generator flue gas with an air stream, thereby forming a combined gas stream;

feeding the combined gas stream to a second gas turbine generator;

mixing exhaust gas from the second gas turbine generator with exhaust gas from the first gas turbine generator, thereby forming a combined exhaust gas stream; and

,

applying the combined exhaust gas stream to the heat recovery steam generator, wherein a CO₂ content of the combined exhaust gas stream is increased by supplementary duct burner firing in the heat recovery steam generator.

2. The method as recited in claim 1, further comprising feeding a supplemental air stream to the second gas turbine generator.

3. The method as recited in claim 2, further comprising cooling the supplemental air stream using an inlet cooler.

4. The method as recited in claim 3, wherein the inlet cooler comprises at least one of an evaporative cooler, an electric chiller or an absorption chiller.

5. The method as recited in claim 4, comprising maintaining a temperature of the combined gas stream exiting the duct burner to about 1,600°

F. or higher.

6. The method as recited in claim 1, wherein the heat recovery steam generator is one of a drum-type or a once-through generator.

7. The method as recited in claim 1, wherein the steam turbine generator heat rejection system is at least one of water-cooled or air-cooled.

8. In a gas turbine system including a first gas turbine generator, a first heat recovery steam generator and a steam turbine generator heat rejection system, a method for CO₂ capture from flue gas in said system, said method comprising:

diverting an amount of heat recovery steam generator flue gas from a CO₂ capture plant; and

mixing the diverted heat recovery steam generator flue gas with an air stream, thereby forming a combined gas stream, wherein

the combined gas stream is fed to a second gas turbine generator;

exhaust gas from the second gas turbine generator is fed to a second heat recovery steam generator;

steam generated in the second heat recovery steam generator is sent to the CO₂ capture plant;

exhaust gas from the second heat recovery steam generator is mixed with exhaust gas from the first gas turbine generator, forming a combined exhaust gas stream; and

the combined exhaust gas stream enters the first heat recovery steam generator, with a CO₂ content of the combined exhaust gas stream increased through supplementary duct burner firing in the first heat recovery steam generator.

9. The method as recited in claim 8, comprising feeding a supplemental air stream to the second gas turbine generator.

10. The method as recited in claim 9, comprising cooling the supplemental air stream using an inlet cooler.

11. The method as recited in claim 10, wherein the inlet cooler comprises at least one of an evaporative cooler, an electric chiller or an absorption chiller.

12. The method as recited in claim 11, wherein the temperature of the combined gas stream exiting the duct burner is maintained at about 1,600°

F. or higher.

13. The method as recited in claim 8, wherein the first heat recovery steam generator comprises one of a drum-type or a once-through steam generator.

14. The method as recited in claim 8, wherein the second heat recovery steam generator comprises one of a drum-type or a once-through steam generator.

15. The method as recited in claim 8, wherein the steam turbine generator heat rejection system is one of water-cooled or air-cooled.