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Steam Turbine, and Steam Turbine Stationary Blade

a steam turbine and stationary blade technology, applied in the field of steam turbines, can solve the problems of reducing the reliability the inability to always set the erosion shield, and the erosive action of the blade surface, so as to reduce the erosive action and improve the reliability

Inactive Publication Date: 2014-01-30
MITSUBISHI HITACHIPOWER SYST LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a way to reduce the build-up of liquid on the blade surface of a stationary blade, which can lead to erosion on the moving blade. By eliminating the liquid film, the invention improves the reliability of the blade system.

Problems solved by technology

Then, the coarse droplets do not sharply turn along the passage as in the case of steam due to its inertial force, and collide against the downstream moving blade at a high speed, which causes erosion to erode the blade surface, or causes loss due to action of a force against the rotation of the turbine blade.
Note that the erosion shield cannot be always set because of its workability.
Further, generally, the mere protection of the blade surface is less than perfect as an erosion countermeasure, accordingly, it is employed together with another erosion countermeasure.

Method used

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  • Steam Turbine, and Steam Turbine Stationary Blade
  • Steam Turbine, and Steam Turbine Stationary Blade
  • Steam Turbine, and Steam Turbine Stationary Blade

Examples

Experimental program
Comparison scheme
Effect test

embodiment 1

[0036]A first embodiment according to the present invention will be described.

[0037]FIGS. 3 to 5 are explanatory diagrams showing the structure where the preset invention is applied to the stationary blade 1 in FIG. 1. FIG. 3 is a schematic perspective diagram of the stationary blade 1 according to the present embodiment, FIG. 4, a cross-sectional diagram in a position indicated with an alternate long and two short dashes line in FIG. 3, and FIG. 5, an enlarged diagram of a blade tail part in FIG. 4.

[0038]As shown in FIG. 3, the stationary blade 1 of the present embodiment is formed by joining a main body 5 and a blade tail part 8 formed as a separate body of the main body 5 along a welding line 9. As shown in FIG. 4, the main body 5 is formed by plastically deforming a metal plate by pressing or the like, and has a hollow blade shape structure having a hollow part 26 inside. On the other hand, the tail part 8 has a suction side plate 20 which is a metal plate forming a suction side...

embodiment 2

[0053]Next, a second embodiment of the present invention will be described using FIG. 7. In the present embodiment, the slit is not formed in the entire region in the stationary blade height direction, but limitedly in a region opposite to the tip part of the moving blade 2 shown in FIG. 1.

[0054]The liquid film is eliminated with the slit 24 and the second slit 23, however, the steam is also sucked at the same time of the elimination of the liquid film. The increment of the steam removal directly influences the degradation of the performance of the steam turbine. Further, the erosion amount by the liquid droplets flying from the stationary blade is increased in accordance with the increment of the circumferential velocity of the moving blade. Accordingly, the blade structure in the 70% or greater region in the blade height direction is formed with the joint body between the main body 5 and the blade tail part 8 shown in the embodiment 1.

[0055]In the present embodiment, it is possibl...

embodiment 3

[0057]Next, a third embodiment of the present invention is shown in FIG. 8 and FIG. 9. FIG. 8 shows a cross-section of the stationary blade according to the third embodiment, and FIG. 9 is an enlarged diagram of the blade tail part of the stationary blade shown in FIG. 8.

[0058]In the present embodiment, the blade tail part 8 is not formed completely independently of the main body 5, but the member forming the blade surface of the main body 5 is extended and applied to the suction side plate 20 of the blade tail part 8. That is, on the suction side of airfoil, the main body 5 and the blade tail part 8 are formed with one metal plate. On the other hand, on the pressure side of airfoil, as in the case of the embodiment 1, the metal plates forming the main body 5 and the blade tail part 8 are separate bodies. The pressure side plate 21 is overlaid on the step part 27 of the suction side plate 20 integrally formed with the main body 5 with a gap therebetween, and its one end is welded an...

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Abstract

The present invention is a steam turbine comprising a turbine stage having a stationary blade and a moving blade provided on the downstream side of the stationary blade in a working fluid flow direction, wherein the stationary blade is formed in a hollow blade shape by deformation processing a metal plate, and wherein a slit to guide liquid droplets deposited on a blade wall surface to the inside of the blade is formed in the blade wall by overlaying an airfoil suction-side metal plate and an airfoil pressure-side metal plate with a gap therebetween in a blade tail part of the stationary blade.

Description

CLAIM OF PRIORITY[0001]The present application claims priority from Japanese Patent application serial No. 2012-167902, filed on Jul. 30, 2012, the content of which is hereby incorporated by reference into this application.TECHNICAL FIELD[0002]The present invention relates to a steam turbine, and more particularly, to a stationary blade structure to eliminate a liquid film generated on a stationary blade surface so as to reduce moving blade erosion due to collision of water droplets, which are generated particularly with wet steam, with a moving blade.BACKGROUND ART[0003]In the final stage of a low pressure turbine or a stage prior to the final stage by 1 or 2 stages, generally, the pressure is very low, accordingly, steam as a working fluid is in a state of wet steam including liquefied minute water droplets (molecules of the vapor). The molecules of the vapor condensed and deposited to the blade surface coalesce to each other and form a liquid film on the blade surface. Further, t...

Claims

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Application Information

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IPC IPC(8): F01D5/28
CPCF01D5/28F01D5/147F01D25/32F05D2240/122
Inventor NAKANO, SUSUMUMIZUMI, SHUNSUKEKUDO, TAKESHISAKAKIBARA, KAZUYAISHIBASHI, KOJIMATSUDA, MASAKI
Owner MITSUBISHI HITACHIPOWER SYST LTD
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