JPS6137762Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a cooling device for a rotor blade embedded in a rotor of an axial flow machine.

[Conventional technology]

Generally, in large-capacity steam turbines, the upstream stage of the reheat turbine (intermediate-pressure turbine) is at high temperature and has a long blade length, so the stress generated in the rotor blades and implants is reduced by the material used for the rotor blades and impeller. The stress may exceed the specified allowable stress. In such cases, the allowable stress of the material has been increased by introducing lower temperature steam or gas into the rotor blade implant. That is,
As shown in FIG. 1, steam 2 whose pressure and temperature have been lowered to some extent due to work is extracted from a mid-stage of a high-pressure turbine 1, and is connected to a cooling steam line 5 consisting of a cooling steam pipe 3 and a cooling steam stop valve 4. through the sleeve 7 to the intermediate pressure turbine 6 and the intermediate pressure outer casing 8 and the intermediate pressure inner casing 9 to the stator vane diaphragm 1.
0 and flows into an impeller 13 consisting of a rotor blade 11 and a blade wheel 12 that supports the rotor blade for cooling.

Alternatively, as shown in FIG. 2, in other turbines, an odd number of balance holes 15 are made in the impeller 14 and a steam scoop 16 is attached to guide the low-temperature steam after the stage upstream to the impeller 17. It was cooling down. Note that S indicates working steam.

[Problem that the invention attempts to solve]

However, according to the configuration shown in FIG. 1, the cooling steam pipe 3, the flange 18 for attaching it to the casing, the tightening bolt 19, the cooling steam,
The structure requires a stop valve 4 to turn off the engine, a sleeve 7 to penetrate the medium-pressure inner and outer compartments and the diaphragm, and a sealing link 20 to prevent unnecessary leakage of the cooling steam 2. However, it was very complicated, expensive, and sometimes caused trouble. In addition, keeping the cooling steam line alive at all times may cause steam and water to backflow and damage the turbine if there is a problem with extremely low flow rate timing, so the timing of opening and closing the cooling steam stop valve 4 is Driving operations were also complicated because of the need to be careful.

In addition, in the one shown in FIG. 2 above, the balance hole 15 is opened at a position away from the rotor blade installation part 21, so that the cooling steam 22 passing through the balance hole 15 is the high-temperature steam leaking through the nozzle labyrinth 23. 24, the temperature rose and the cooling effect of the rotor blade implanted portion 21 was reduced.

[Means for solving problems]

The present invention provides a rotor blade implantation part that cools the rotor blade implantation part by drilling a passage hole in the impeller and guiding steam from the downstream side of the impeller to the upstream side of the impeller through the passage hole. This is an improved cooling device, and its configuration is as illustrated in Fig. 1.
A guide piece and a cut-off part are formed to face each other, and (b) on the steam upstream side, a guide piece is formed at the edge in the rotational direction of the impeller, and a cut-off part is formed opposite to the guide piece on the steam upstream side. A guide piece and a cut-off part are formed on the steam downstream side so as to be opposite to the upstream side.

The passage holes may be formed in the rotor blade implant, the blade wheel, or both, and such selection depends on the degree of cooling required. This can be done as appropriate.

[Effect]

When the guide piece and the cut-off part are formed as described above, as schematically shown in FIG. A high-pressure section is formed, and as a result, low-temperature, low-pressure steam on the downstream side flows toward the upstream side through the passage hole, thereby cooling the rotor blade implantation section.

〔Example〕

An embodiment of the invention will be described with reference to FIGS. 1 to 3. The impeller 30 is fitted with a rotor (not shown) or has an impeller 31 formed integrally with the rotor, and a groove 3 formed at the circumferential end of the impeller 31.
The rotating blade 34 is fixed to the rotor blade 2 via a implanted portion 33, and the implanted portion 33 and the impeller 31 are provided with oblong passage holes 35 and 36 in the rotor axial direction. Guide pieces 37 and 38 having a triangular cross section are provided at the edges of the steam upstream openings of these passage holes 35 and 36 in the impeller rotation direction, and furthermore, guide pieces 37 and 38 having a triangular cross section are provided at the edges of the openings on the side opposite to the guide pieces. portions 39 and 40 are formed, respectively, and these passage holes 35 and 36
A guide piece 41 is provided on the edge of the opening on the upstream side of the steam so as to be opposite to the opening on the upstream side of the steam.
42 and cut-off portions 43 and 44 are formed.

FIG. 2 shows the passage hole 35, the guide pieces 37, 41,
This diagram schematically shows the cut-off parts 39 and 43. According to this configuration, when the impeller rotates in the direction of the arrow, the guide piece 41 and the cut-off part 43 are cut off at the downstream opening of the passage hole 35 for the steam S. As a result, the pressure in this area is increased, and conversely, the guide piece 37 is formed so that the upstream side opening is on the opposite side from the downstream side.
The pressure is lowered by the action of the cut-off portion 39, and as a result, the steam LS flows through the passage hole 35 from the downstream side of the turbine driving steam S to the upstream side. Since the steam LS flowing through this passage hole 35 is guided from the downstream side, it is lower temperature than the turbine driving steam S.
The pressure is low, so the blade implants are exposed to this steam.
It will be cooled by LS. The amount of cooling steam LS can be arbitrarily changed without affecting the efficiency of the turbine by selecting the size of the passage hole, the number of holes, the guide piece, and the shape of the cutout.

In addition, when determining which part of the implantation part 33 of the rotor blade 34 and the blade wheel 31 to drill a passage hole, stress fringes a, b, In order to ensure the reliability of the impeller, it is desirable to avoid areas where c... is dense.

[Effect of idea]

According to the present invention, the cooling steam flows smoothly through the passage holes, and the present invention can be said to be an extremely effective means for cooling the implanted portion of the impeller, particularly the rotor blade.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a rotor blade embedded cooling device according to an embodiment of the present invention, Fig. 2 is a diagram schematically showing an implementation of the present invention, and Fig. 3 is a perspective view showing the embedded part and the blade. Figures 4 and 5 showing the stress distribution of a vehicle are cross-sectional views showing the prior art. 30... Impeller, 31... Impeller, 33... Implanted portion, 34... Moving blade, 35, 36... Passage hole, 3
7, 38, 41, 42...Guide piece, 39, 40,
43, 44...Cut off part.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A passage hole is bored in the impeller and steam is guided from the downstream side of the impeller to the upstream side through the passage hole to cool the rotor blade embedded part. A guide piece having a triangular cross section is provided on the edge of the opening on the steam upstream side of the passage hole in the impeller rotation direction, and a cut-out portion is further provided on the edge of the opening on the side opposite to the guide piece. , and a guide piece and a cut-off portion are formed on the edge of the opening on the downstream side of the steam in the passage hole so as to be opposite to the opening on the upstream side. Wing implant cooling system. (2) The rotor blade embedded cooling device according to claim 1, wherein the passage hole is bored in the rotor blade embedded. (3) The rotor blade embedded cooling device according to claim 1, wherein the passage hole is formed in the blade wheel.