JPH09280002A - Gas turbine moving blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve thermal efficiency of a gas turbine without deteriorating cooling performance of a blade profile part and a platform part by providing a serpentine flow passage on the blade profile part so as to perform cooling by steam, and providing a convection cooling passage or film cooling holes on the platform part 7 as to perform cooling by air. SOLUTION: The interior of a blade profile part 101 is provided with a serpentine flow passage 103 of which the inside is formed along the outer face of the blade profile part 101, and a blade root part is provided with a steam supply port 104 and a steam collect port 105. The platform part 102 is provided with a convection cooling passage 107 or film cooling holes 108 through which sealing air is passed for convection cooling or film cooling of the platform part 102A. Consequently, the blade profile part 101 is cooled by steam, and the platform part 102 is cooled by air. In addition, the air after cooling the platform part 102 is released in turbine main flow gas, but the air is the sealing air, and hence it is unnecessary to release surplus cooling medium in the turbine main flow gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine blade cooling technique.

[0002]

2. Description of the Related Art Conventionally, in a high temperature gas turbine used in a combined plant or the like, in order to protect the blade from the heat of the high temperature gas, a passage is provided inside the blade to allow cooling air having a relatively low temperature to flow therethrough. The temperature is kept lower than the gas temperature. In this blade cooling system using air, the cooling air supplied from the blade root passes through the cooling passage inside the blade and is then discharged to the outside of the blade (in the mainstream gas of the turbine) from the hole provided at the outer edge of the blade. are doing.

In contrast to this air cooling method, a blade cooling method using steam has been considered in recent years. In the blade cooling method using steam, the steam used for cooling is collected without being released, and this can be expected to improve the thermal efficiency of the gas turbine. In a combined plant, it is also possible to send the recovered steam to a steam turbine to improve the efficiency of the entire plant.

[0004]

In the moving blade of the gas turbine, the hot gas is directly affected by the airfoil portion and the platform portion, and these portions need to be uniformly cooled throughout. Usually, in order to perform such cooling, it is conceivable to provide a meandering passage (so-called serpentine passage) having a shape in which the inner surface is along the outer surface of the airfoil portion or the platform portion as a cooling passage inside.

In this case, since the airfoil portion has a certain thickness, it is possible to relatively easily provide the meandering passage as described above inside even when it is produced by precision casting. On the other hand, since the platform part has a thin and wide structure, it is difficult and uneconomical to provide the above serpentine passages in the entire interior by precision casting.

Further, in order to increase the efficiency of the entire combined plant, it is necessary to suppress the pressure loss caused in the cooling process of the gas turbine blades and supply the recovered steam to the steam turbine while keeping the pressure as high as possible. If cooling steam is passed through the meandering passage provided in the entire inside of the platform, the pressure loss will become extremely large, and it will not be possible to expect much improvement in efficiency.

[0007]

In order to solve the above problems, the present invention provides a gas turbine rotor blade with a steam supply port and a steam recovery port at the blade root portion, and communicates with the steam supply port and the steam recovery port. And a convection cooling passage for convectively cooling the platform or a film cooling hole for film cooling through the seal air.

By adopting such a structure, the airfoil portion is cooled by steam and the platform portion is cooled by air. The air that has cooled the platform is released into the turbine mainstream gas, but since the air is originally seal air that is released into the turbine mainstream gas, it is not necessary to release an extra cooling medium into the turbine mainstream gas. Absent.

[0009]

1 is a longitudinal sectional view showing an embodiment of a gas turbine rotor blade according to the present invention. In the figure, inside the airfoil portion 101, a meandering passage (serpentine flow passage) 1 having a shape in which the inner surface is along the outer surface of the airfoil portion 1
03 is provided, and the blade root portion is provided with a steam supply port 104 and a steam recovery port 105. The serpentine channel 103 is divided into a channel located on the blade leading edge side and a channel located on the blade trailing edge side.

The cooling steam supplied from the steam supply port 104 is divided into two directions by a bifurcated passage provided in the blade root portion, one is supplied to the serpentine flow passage 103 on the blade leading edge side, and the other is supplied to the blade trailing edge side. Serpentine channel 103
Is supplied to. As shown by the arrows in FIG. 1, in both flow paths, the cooling steam supplied from the steam supply port 104 meanders from the blade edge side toward the blade central portion. Then, the steam sent to the central portion of the blade advances to the steam recovery port 105 through the passage in the root portion of the blade and is recovered.

FIG. 2 is a sectional view taken along line AA of FIG. In the figure, a plurality of film cooling holes 108 are opened on the platform section 102.
Platform part 1 by cooling air blown from 08
Film cool 02. A broken line extending toward the film cooling hole 108 is a cooling air passage for supplying cooling air to the film cooling hole 108.

FIG. 3 is a sectional view taken along line BB of FIG. In the figure, the platform section 102 is provided with a convection cooling passage 107 for performing convection cooling by flowing cooling air. FIG. 4 shows a sectional view taken along the line CC of FIG.

FIG. 5 shows the supply and recovery paths of cooling steam and cooling air according to an embodiment of the present invention. In the figure, the cooling steam 106 is supplied to the first stage moving blades through the turbine rotor 110. The steam that has cooled the first-stage rotor blades passes through the turbine rotor 110, cools the second-stage rotor blades, and then is recovered through the turbine rotor 110.

Further, for cooling the platform section 102, seal air extracted from the compressor is used. Since there is a pressure difference between the seal side and the turbine mainstream side, the air flows into the turbine mainstream gas through the convection cooling passage 107 and the film cooling hole 108 provided in the platform 102. At that time, the platform section 10
2 will contribute to cooling.

[0015]

According to the present invention, the thermal efficiency of the gas turbine can be improved and the manufacturing cost of the blade can be suppressed without lowering the cooling performance of the airfoil portion and the platform portion. Further, if the present invention is applied to a gas turbine in a combined plant, the efficiency of the entire plant will be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a gas turbine rotor blade according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA in FIG.

FIG. 3 is a sectional view taken along line BB in FIG. 2;

FIG. 4 is a sectional view taken along line CC of FIG.

FIG. 5 is an internal cross-sectional view of a gas turbine showing supply and recovery paths of cooling steam and cooling air according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 101 Airfoil 102 Platform 103 Serpentine flow path 104 Steam inlet 105 Steam recovery port 106 Cooling steam 107 Convection cooling passage 108 Film cooling hole 109 Cooling air 110 Turbine rotor

Claims (1)

[Claims] 1. In a gas turbine rotor blade, a steam supply port and a steam recovery port are provided at a blade root portion, a meandering passage communicating with the steam supply port and the steam recovery port is provided inside the airfoil portion, and seal air is passed through. A gas turbine moving blade, comprising: a convection cooling passage for convectively cooling a platform portion or a film cooling hole for film cooling provided on the platform portion.