JP2008274818A - Gas turbine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine cooling a gas turbine blade with reduced flow rate of coolant, and improving heat efficiency. <P>SOLUTION: The gas turbine has structure to reduce consumption of cooling air supplied from a compressor 3, by guiding the cooling air that cooled a turbine stator blade 21 disposed to a rear stage side with respect to a working gas flow direction, to a turbine stator blade 20 disposed on a front stage side through a flow passage in a turbine casing to surely cool each turbine blade, and then flowing the cooling air out to a working gas flow passage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gas turbine having a cooling system for cooling a stationary blade using air extracted or discharged from a compressor as a refrigerant.

  Conventionally, a gas turbine for power generation has a compressor and a turbine arranged on one shaft, and burns fuel in the combustor using compressed air compressed by the compressor as an oxidant to generate high-temperature and high-pressure gas. The turbine is configured to be driven by high-pressure gas. And it produces electric power by driving the generator couple | bonded with the turbine shaft.

  It is desirable that the amount of power generation is greater than the amount of fuel that has been added. For this purpose, it is important to improve the performance of the gas turbine. By the way, the temperature of the gas turbine high-temperature combustion gas exceeds the operating temperature of the material used around the working gas flow path, and in the turbine blade that would be exposed to the hottest combustion gas in the current gas turbine, As a hollow structure, a method of cooling a blade by supplying a cooling medium to the hollow portion is generally employed.

  What is important in this cooling method is that, in a gas turbine, cooling air that serves as a cooling medium is often extracted from a compressor and used. Therefore, a large amount of cooling air consumption reduces the efficiency of the gas turbine.

  As a conventional cooling structure for a turbine stationary blade, there is a structure in which cooling air that has cooled the stationary blade on the upstream side in the working medium flow direction is cooled by introducing the cooling air into the stationary blade on the downstream side again. .

JP 2002-327627 A

  The temperature of the working medium of the gas turbine is highest at the combustor outlet, and decreases as it proceeds downstream with respect to the flow direction of the working medium. Therefore, the temperature of the stationary blades exposed to the working medium also decreases as the temperature of the stationary blades moves downstream with respect to the working medium flow direction.

  Here, as in the prior art described above, cooling is performed from the stationary blade on the upstream side with respect to the flow direction of the working medium, and the stationary blade on the downstream side is cooled using the cooling air that has cooled the stationary blade on the upstream side. When cooled, the temperature of the cooling air that has cooled the stationary blade on the upstream side is higher than the temperature of the cooling air before cooling the stationary blade on the upstream side, and is necessarily lower than the temperature of the stationary blade on the downstream side. Is not limited.

  An object of the present invention is to provide a gas turbine capable of cooling gas turbine blades with a small refrigerant flow rate and improving thermal efficiency.

  To achieve the above object, a compressor for compressing air, a turbine having a plurality of turbine stages, and a cooling system for cooling the stationary blades and turbine wheels of the turbine with air extracted or discharged from the compressor, In the gas turbine provided, the cooling air supplied from the compressor to the turbine is an internal flow path of a stationary blade disposed on the rear stage side with respect to the flow direction of the working gas, a flow path provided in the turbine casing, the front stage side The cooling system is configured so as to flow in the order of the internal path of the stationary blades arranged in the flow, and to flow out from the preceding stationary blade to the working gas flow path.

  According to the present invention, it is possible to provide a gas turbine capable of cooling gas turbine blades with a small refrigerant flow rate and improving thermal efficiency.

  FIG. 1 is a circuit diagram schematically showing the entire configuration of a gas turbine. As shown in FIG. 1, a gas turbine includes a compressor 1 that compresses intake air and supplies the compressed air, and a combustor that burns the compressed air from the compressor 1 together with fuel to generate high-temperature and high-pressure combustion gas. 2 and a turbine 3 that obtains rotational power by the combustion gas from the combustor 2. A compressor rotor (not shown) of the compressor 1 is concentrically connected to a turbine rotor 6 (see FIG. 2 described later) of the turbine 3 by a central shaft 4. For example, a generator rotor (not shown) is concentrically connected to the turbine rotor 6 and converted into electric energy.

  FIG. 2 is a cross-sectional view showing a detailed structure of the turbine which is a main part of the embodiment of the gas turbine of the present invention. The turbine 3 provided in the present embodiment includes a casing 10, stationary blades 20 and 21 disposed on the inner periphery of the casing 10, and a turbine rotor 6 disposed rotatably inside the casing 10. .

  The casing 10 includes a substantially cylindrical peripheral wall 11, and shrouds 12 and 13 arranged at predetermined intervals in the turbine rotor longitudinal direction on the inner peripheral portion of the peripheral wall 11. The shroud 13 has a compressed air flow path 14. The outer ring 22 of the stationary blade 20 and the outer ring 23 of the stationary blade 21 are supported on the shrouds 12 and 13 adjacent to each other in the longitudinal direction of the turbine rotor 6, and in the longitudinal direction of the stationary blade outer rings 22 and 23 and the turbine rotor 6. The adjacent shrouds 12 and 13, the partition wall fixed to the casing peripheral wall 11 on the outer peripheral side of the stationary blade 20, and the casing peripheral wall 11 define the cavity 15 on the outer peripheral side of the stationary blade 20 and the cavities 16 and 17 on the outer peripheral side of the stationary blade 21. Is formed. The casing peripheral wall 11 is provided with one or a plurality of air introduction holes 18 connected to the cavity 17. The air introduction hole 18 is connected to an extraction slit or the like provided in an extraction stage having a required pressure in the compressed air flow path of the compressor 1 via independent pipes 5.

  The stationary blade outer ring 22 is provided with an opening 25 for connecting the cavity 15 and the stationary blade inner flow path 24. Further, the stationary blade outer ring 23 is provided with an opening 27 for connecting the cavity 16 and the flow channel 26 in the stationary blade, and an opening 28 for connecting the cavity 17 and the flow channel 26 in the stationary blade. A plurality of stationary blades 20 and 21 are arranged at a predetermined interval in the circumferential direction to form a single-stage stationary blade cascade, and are supported via stationary blade inner rings 29 and 30 that connect the inner circumferential sides. The stationary vane diaphragms 31 and 32 are provided. The vane inner ring 29 is provided with an opening 35 that connects the vane inner flow path 24 and the cavity 33 in the vane diaphragm 31. Further, the stator blade inner ring 30 is provided with an opening 36 that connects the stator blade inner flow path 26 and the cavity 34 of the stator blade diaphragm 32. An orifice is provided in front of the stationary blade diaphragms 31 and 32. A plurality of rotor blades 40 are annularly arranged on the outer periphery of the turbine rotor to constitute a rotor blade cascade. The stationary blade cascade of the same paragraph is arranged on the front side of the rotor blade cascade of each stage.

  When the gas turbine having the above configuration is operated, as indicated by a dotted arrow 50, for example, compressed air extracted from the compressor 1 flows into the cavity 17 on the outer peripheral side of the stationary blade 21 through the pipe 5 and the air introduction hole 18. . The compressed air in the cavity 17 flows into the stationary blade inner passage 26 through the opening 28 provided in the stationary blade outer ring 23, and cools the stationary blade 21. The compressed air that has flowed into the stationary blade inner passage 26 branches off from the dotted arrow 50 at the inlet 36 of the opening provided in the stationary blade inner ring 30 as indicated by the dotted arrow 51. The compressed air indicated by the dotted arrow 51 cools the turbine rotor 6 through the opening 36 provided in the stationary blade inner ring 30, the cavity 34 provided in the stationary blade diaphragm 32, and the orifice 38, and then joins the working medium flow path 7. .

  In the gas turbine, the temperature of the working medium is the highest at the combustor outlet, and the working medium temperature decreases as it proceeds downstream in the working medium flow direction. Accordingly, the temperature of the stationary blades exposed to the working medium also decreases as the temperature of the stationary blades goes downstream with respect to the working medium flow direction. Therefore, at the stage where the compressed air passes through the opening 27 provided in the stationary blade outer ring 23, the temperature of the compressed air is at most the metal temperature of the stationary blade 21, and is surely lower than the metal temperature of the stationary blade 20. Can cool the stationary blade 20 positioned upstream of the stationary blade 21 by using compressed air at the stage of passing through the opening 27 provided in the stationary blade outer ring 23.

  Therefore, the compressed air indicated by the dotted arrow 52 includes the opening 27 provided in the stationary blade outer ring 23, the cavity 16, the compressed air flow path 14 provided in the shroud 13, the cavity 15 outside the stationary blade 20 and the stationary blade outer ring 22. The air flows into the stationary blade flow path 24 through the opening 25 provided to cool the stationary blade 20. The compressed air indicated by the dotted arrow 52 cools the turbine rotor 6 through the opening 35 provided in the stationary blade inner ring 29, the cavity 33 provided in the stationary blade diaphragm 31, and the orifice 37, and then joins the working medium flow path 7. .

  Although the cooling system has been described in the above embodiment, for example, the present invention is applied to the case where the stationary blade 20 has a cooling hole for connecting the stationary blade flow path 24 and the working medium flow path 7 for performing film cooling. It is effective to do.

The system system diagram of a gas turbine. 1 is a longitudinal sectional view of a rotor of a gas turbine that is an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Combustor 3 Turbine 6 Turbine rotor 10 Casing 11 Circumferential wall 12, 13 Shroud 14 Compressed air flow path 15, 16, 17, 33, 34 Cavity 18 Air introduction hole 20, 21 Stator blade 22, 23 Stator blade outer ring 24 , 26 Inner flow passages 25, 27, 28 Openings 29, 30 Stator blade inner rings 31, 32 Stator blade diaphragm 40 Moving blade

Claims (1)

In a gas turbine comprising: a compressor that compresses air; a turbine having a plurality of turbine stages; and a cooling system that cools a stationary blade and a turbine wheel of the turbine with air extracted or discharged from the compressor.
The cooling air supplied from the compressor to the turbine is a flow path of a stationary blade disposed on the rear stage side with respect to the flow direction of the working gas, a flow path provided in the turbine casing, and a stationary blade disposed on the front stage side. A gas turbine characterized in that the cooling system is configured so as to flow in the order of the internal paths and flow out from the preceding stage stationary vane to the working gas flow path.

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