GAS TURBINE POWER PLANT WITH FLUE GAS RECIRCULATION AND OXYGEN-DEPLETED COOLING GAS

• US 20120240590A1
• Filed: 03/21/2012
• Published: 09/27/2012
• Est. Priority Date: 03/22/2011
• Status: Active Grant

• Current Assignee: Ansaldo Energia IP UK Limited (Ansaldo Energia SPA)
• Original Assignee: Alstom Technology Ltd. (Alstom SA)
• Inventors: Rofka, Stefan, Benz, Eribert, Guethe, Felix, HELLAT, Jaan, Hoevel, Michael, Burdet, Andre, Sander, Frank
• Granted Patent: US 9,297,311 B2
• Time in Patent Office: Days
• US Class Current: 60/772
• CPC Class Codes: F01D 25/08 Cooling of machines or engines in general F01P; Heating; Heat-insulation of blade-carrying members, of blades F01D5/00
• CPC Class Codes: F01K 23/10 with exhaust fluid of one cycle heating the fluid in another cycle F01K17/025 takes precedence
• CPC Class Codes: F02C 1/08 Semi-closed cycles
• CPC Class Codes: F02C 3/30 Adding water, steam or other fluids for influencing combustion, e.g. to obtain cleaner exhaust gases F02C7/141, F02C7/30, F01D21/00, F01K21/04, F23D11/10 take precedence
• 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 6/18 using the waste heat of gas-turbine plants outside the plants themselves, e.g. gas-turbine power heat plants using waste heat as source of energy for refrigeration plants F25B27/02; using the waste heat of a gasturbine for steam generation or in a steam cycle see F01K23/10
• CPC Class Codes: F02C 7/04 Air intakes for gas-turbine plants or jet-propulsion plants
• CPC Class Codes: F02C 7/143 before or between the compressor stages
• CPC Class Codes: F05D 2270/082 with as little NOx as possible
• 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

A method is disclosed for operating a gas turbine power plant having a gas turbine, a heat recovery steam generator and an flue gas splitter which splits flue gases into a first flue gas flow for recirculation into an inlet flow of the gas turbine and into a second flue gas flow for discharge to an environment. An oxygen-depleted gas can be used in an open cooling system for cooling hot gas parts of the gas turbine. A split compressor intake can be provided for separate feed of recirculated flue gas and fresh air into a compressor intake. Compressor blades can include a separating band which blocks intermixing of recirculated flue gas and fresh air during compression.

Claims

1. A method for operating a gas turbine power plant having a gas turbine, a heat recovery steam generator and an flue gas splitter for splitting flue gases into a first flue gas flow for recirculation into an inlet flow of the gas turbine and into a second flue gas flow for discharge to an environment, the method comprising:

providing an oxygen-depleted gas; and

cooling hot gas parts of the gas turbine in an open cooling system with oxygen-depleted gas.

2. The method as claimed in claim 1, wherein the cooling gas contains flue gases of the gas turbine, or a gas mixture which consists of more than 50% of flue gases of the gas turbine.

3. The method as claimed in claim 1, wherein the cooling gas is steam.

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

introducing the first flue gas flow into a compressor intake without mixing with fresh air; and

tapping off at least a portion of the first flue gas flow compressed in the compressor tapping as cooling gas.

5. The method as claimed in claim 4, comprising:

feeding the first flue gas flow and the fresh air to the compressor in a radially stepped manner.

6. The method as claimed in claim 5, comprising:

feeding the first flue gas flow and the fresh air to the compressor via concentric annuluses.

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

feeding the fresh air to the compressor via an inner annulus; and

feeding the first flue gas flow via an outer annulus.

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

introducing the first flue gas flow via feeds arranged upstream of the compressor intake in a circumferentially distributed manner on a diameter of an intake duct.

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

adding fresh air, at partial load and/or during start-up of the gas turbine, to the first flue gas flow via a control element before the first flue gas flow is introduced into the compressor.

17. The method as claimed in claim 2, comprising:

introducing the first flue gas flow into a compressor intake without mixing with fresh air; and

tapping off at least a portion of the first flue gas flow compressed in the compressor tapping as cooling gas.

18. The method as claimed in claim 2, comprising:

introducing the first flue gas flow via feeds arranged upstream of the compressor intake in a circumferentially distributed manner on a diameter of an intake duct.

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

adding fresh air, at partial load and/or during start-up of the gas turbine, to the first flue gas flow via a control element before the first flue gas flow is introduced into the compressor.

10. A gas turbine power plant with flue gas recirculation, comprising:

a gas turbine with a governor;

a heat recovery steam generator;

a compressor intake through which an inlet flow will enter a compressor of the gas turbine; and

an flue gas splitter for splitting flue gases into a first flue gas flow for recirculation into an inlet flow of the gas turbine and into a second flue gas flow for discharge to an environment,

wherein the compressor intake is split into sectors connected with a flow passage of the compressor, with a feed for fresh air leading through a first sector of the compressor intake, and with a feed for the first flue gas flow leading through a second sector of the compressor intake.

11. The gas turbine power plant as claimed in claim 10, comprising:

an intake baffle plate for dividing the first sector and the second sector;

wherein the first sector and the second sector of the compressor intake are constructed as concentric annuluses at a connection to the flow passage of the compressor.

12. The gas turbine power plant as claimed in claim 10, wherein an area ratio of a connecting area of the first sector for the flow passage of the compressor to a connecting area of the second sector for the flow passage of the compressor is selected to be equal to a ratio of volumetric flows of supplied fresh air to the first flue gas flow during design conditions of the gas turbine.

13. The gas turbine power plant as claimed in claim 10, comprising:

a multiplicity of feed passages for introducing the first flue gas flow into the compressor, arranged in the compressor intake in a circumferentially distributed manner on a circle which is concentric to an axis of the gas turbine.

14. The gas turbine power plant as claimed in claim 13, comprising:

stator-blade separating band segments and/or rotor-blade separating band segments on compressor blades for block mixing of gases of recirculated first flue gas flow with fresh air in the compressor.

15. The gas turbine power plant as claimed in claim 14, comprising:

a control element for controlled adding of fresh air to recirculated first flue gas flow.

20. The gas turbine power plant as claimed in claim 10, comprising:

stator-blade separating band segments and/or rotor-blade separating band segments on compressor blades for block mixing of gases of recirculated first flue gas flow with fresh air in the compressor.

16. A compressor blade, comprising:

a blade root;

a blade airfoil for a gas turbine configured with flue gas recirculation; and

a separating band segment arranged between the blade root and a free end of the blade airfoil facing away from the blade root and forms a right angle to the longitudinal axis of the blade,

wherein separating band segments of all blades of a compressor stage are configured such that, when in an installed position, will form an essentially closed annular separating band which lies perpendicular to an axis of a gas turbine to block mixing of recirculated first flue gas flow with fresh air in a compressor.