Method for Generating Energy in an Energy Generating Installation Having a Gas Turbine, and Energy Generating Installation Useful for Carrying Out the Method

• US 20080010967A1
• Filed: 02/06/2007
• Published: 01/17/2008
• Est. Priority Date: 08/11/2004
• Status: Abandoned Application

• Current Assignee: Alstom Technology Ltd. (Alstom SA)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Abbott, David, Griffin, Timothy, Buecker, Dominikus
• Application Number:
  US11/671,515
• Publication Number:
  US 20080010967A1
• Time in Patent Office: Days
• US Class Current: 60/39.182
• CPC Class Codes: B01D 53/22 by diffusion manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00
• 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: Y02E 20/16 Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]

Abstract

In a method for generating energy in an energy generating installation (10) having a gas turbine (12), in a first step, an oxygen-containing gas is compressed in a compressor (13, 14) of the gas turbine (12), in a second step the compressed gas is supplied, with the addition of fuel, for combustion in a combustion chamber (15), in a third step the hot flue gas from the combustion chamber (15) is expanded in a turbine (16) of the gas turbine (12) so as to perform work, and, in a fourth step, a branched-off part stream of the expanded flue gas is recirculated into a part of the gas turbine (12) lying upstream of the combustion chamber (15) and is compressed. A reduction in the CO₂ emission, along with minimal losses of efficiency, is achieved in that carbon dioxide (CO₂) is separated from the circulating gas in a CO₂ separator (19), and in that measures are taken to compensate for the efficiency losses in the gas turbine cyclic process which are associated with the CO₂ separation.

Claims

1. A method for generating energy in an energy generating installation having a gas turbine, the method comprising:

compressing an oxygen-containing gas in a compressor of the gas turbine;

thereafter supplying the compressed, with fuel, for combustion in a combustion chamber, to generate hot flue gas;

thereafter expanding the hot flue gas from the combustion chamber in a turbine of the gas turbine to perform work, to generate expanded flue gas;

thereafter recirculating a branched-off part stream of the expanded flue gas into a part of the gas turbine upstream of the combustion chamber, and compressing said recirculated expanded flue gas;

separating carbon dioxide from the circulating gas in a CO₂ separator; and

compensating for efficiency losses in the gas turbine cyclic process associated with the CO₂separating.

2. The method as claimed in claim 1, wherein separating carbon dioxide is only partially separating carbon dioxide from the circulating gas.

3. The method as claimed in claim 1, further comprising:

before said compressing, enriching air with oxygen to generate the oxygen-containing gas compressed in the compressor of the gas turbine.

4. The method as claimed in claim 3, wherein said enriching air with oxygen is performed in an oxygen enrichment device including operating air separation membranes at low temperatures.

5. The method as claimed in claim 1, further comprising, between said expanding and said recirculating, generating steam with the expanded flue gas in a waste heat recovery steam generator.

6. The method as claimed in claim 1, wherein compressing the oxygen-containing gas comprises compressing in the compressor in at least two compressor stages connected in series, and further comprising intermediately cooling the oxygen-containing gas between compressing in the at least two compressor stages.

7. The method as claimed in claim 6, comprising:

adding the recirculated flue gas to the oxygen-containing gas upstream of the first compressor stage and

separating the carbon dioxide from the intermediately cooled oxygen-containing gas before entry into the second compressor stage.

8. The method as claimed in claim 7, wherein separating the carbon dioxide comprises passing the oxygen-containing gas through a CO₂ separator, setting the quantity of gas flowing through the CO₂ separator by a first adjustable valve arranged in a bypass to the CO₂ separator, and regulating the stream conducted through the CO₂ separator by a second valve arranged upstream of the CO₂ separator.

9. The method as claimed in claim 8, comprising:

opening the first adjustable valve in the bypass completely during a starting phase, during part-load operation, or during an emergency shutdown, to short-circuit the CO₂ separator.

10. The method as claimed in claim 7, further comprising:

cooling the branched-off part stream of the flue gas in a cooler before said recirculating, optionally extracting water from the part stream.

11. The method as claimed in claim 7, further comprising:

interrupting the branched-off part stream when the gas turbine cyclic process is to be run in a standard mode without the separation of carbon dioxide.

12. The method as claimed in claim 7, wherein separating the carbon dioxide comprises separating in the CO₂ separator in a wet method with membranes.

13. The method as claimed in claim 7, wherein intermediate cooling comprises spraying water into the stream of oxygen-containing gas.

14. The method as claimed in claim 7, further comprising:

inlet fogging with water into the stream of oxygen-containing gas at the inlet of the second compressor stage.

15. The method as claimed in claim 1, comprising:

compressing the branched-off part stream of flue gases in a separate compressor before said recirculating into the gas turbine.

16. The method as claimed in claim 15, comprising:

compressing the carbon dioxide from the compressed part stream of flue gas; and

thereafter adding the compressed part stream to the oxygen-containing gas upstream of the combustion chamber.

17. The method as claimed in claim 16, wherein separating the carbon dioxide (CO₂)comprises:

passing the compressed part stream through a CO₂ separator;

setting the quantity of gas flowing through the CO₂ separator by a first adjustable valve arranged in a bypass to the CO₂ separator; and

regulating the stream conducted through the CO₂ separator with a second valve arranged upstream of the CO₂ separator.

18. The method as claimed in claim 17, comprising:

cooling the compressed part stream in a cooler before entry into the CO₂ separator;

precooling the compressed part stream in a regenerative heat exchanger before entry into the cooler; and

preheating the compressed part stream after leaving the CO₂ separator in the regenerative heat exchanger.

19. The method as claimed in claim 15, comprising:

cooling the branched-off part stream of flue gas in a cooler before said recirculating, and optionally extracting water from the branched-off part stream.

20. The method as claimed in claim 15, comprising:

intermediately heating the flue gas expanded in the turbine of the gas turbine expanding the intermediately heated flue gas in a second turbine; and

driving the separate compressor with the second turbine.

21. The method as claimed in claim 1, comprising:

separating the carbon dioxide (CO₂) from the flue gas expanded in the turbine of the gas turbine; and

thereafter, branching off a part stream and recirculating said part stream to the inlet of the compressor of the gas turbine.

22. The method as claimed in claim 21, comprising:

cooling the flue gas expanded in the turbine of the gas turbine in a cooler before said separating of the carbon dioxide (CO₂), and optionally extracting water from the flue gas.

23. The method as claimed in claim 21, wherein expanding the flue gas comprises expanding to a few bar in the turbine of the gas turbine, and comprising further expanding the flue gas in an exhaust gas turbine after said separating of the carbon dioxide (CO₂).

24. The method as claimed in claim 21, further comprising:

precompresssing the oxygen-containing gas in a second compressor before said compressing in the gas turbine, and thereafter intermediately cooling the oxygen-containing gas in an intermediate cooler.

25. An energy generating installation useful for carrying out the method as claimed in claim 1, comprising:

a gas turbine with a compressor having an outlet, a turbine having an inlet and an outlet, and a combustion chamber arranged between the compressor outlet and the turbine inlet, and an exhaust gas line connected to the turbine outlet of the turbine;

a recirculation line branching off from the exhaust gas line, configured and arranged to recirculate gas into a part of the gas turbine upstream of the combustion chamber;

a CO₂ separator arranged within a gas circuit formed by the recirculation line; and

means for compensating for efficiency losses in the gas turbine cyclic process associated with CO₂ separation.

26. The energy generating installation as claimed in claim 25, further comprising:

an oxygen enrichment device configured and arranged to enrich with oxygen the air sucked in by the compressor, arranged upstream of the inlet of the compressor of the gas turbine.

27. The energy generating installation as claimed in claim 25, further comprising:

a waste heat recovery steam generator arranged in the exhaust gas line.

28. The energy generating installation as claimed in claim 25, wherein the compressor of the gas turbine comprises two compressor stages, wherein the CO₂ separator is arranged between the two compressor stages, further comprising an intermediate cooler between an outlet of the first compressor stage and an inlet of the CO₂ separator, and wherein the recirculation line is connected to the inlet of the first compressor stage.

29. The energy generating installation as claimed in claim 28, further comprising:

a bypass including a first adjustable valve bridging the CO₂ separator; and

a second valve configured and arranged to regulate the stream conducted through the CO₂ separator, arranged upstream of the CO₂ separator.

30. The energy generating installation as claimed in claim 25, wherein the recirculation line returns to the inlet of the combustion chamber, and further comprising a separate compressor arranged in series with the CO₂ separator in the recirculation line.

31. The energy generating installation as claimed in claim 30, further comprising:

a cooler between the separate compressor and the CO₂ separator; and

a regenerative heat exchanger arranged upstream of the cooler through which recirculated gas flows to the cooler and gas emerging from the CO₂ separator flows to the combustion chamber.

32. The energy generating installation as claimed in claim 30, further comprising:

a bypass bridging the CO₂ separator, the bypass including a first adjustable valve; and

a second valve configured and arranged for regulating the stream conducted through the CO₂ separator, arranged upstream of the CO₂ separator.

33. The energy generating installation as claimed in claim 30, further comprising:

an intermediate heater and a second turbine arranged in series in the exhaust gas line.

34. The energy generating installation as claimed in claim 25, further comprising a valve arranged in the recirculation line.

35. The energy generating installation as claimed in claim 25, further comprising:

a cooler arranged in the recirculation line.

36. The energy generating installation as claimed in claim 25, wherein the CO₂ separator is arranged in the exhaust gas line, wherein the recirculation line is returned from an outlet of the CO₂ separator to an inlet of the compressor of the gas turbine, and further comprising a valve in the recirculation line.

37. The energy generating installation as claimed in claim 36, further comprising:

a cooler arranged upstream of the inlet of the CO₂ separator; and

an exhaust gas turbine in the exhaust gas line at the outlet of the CO₂ separator.

38. The energy generating installation as claimed in claim 36, further comprising:

a second compressor with a following intermediate cooler arranged upstream of the inlet of the compressor of the gas turbine.

39. The energy generating installation as claimed in claim 26, wherein the oxygen enrichment device comprises air separation membranes.