RU2244182C1 - Labyrinth packing - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: ring comb of the turbine is mounted with a spaced relation to the stator. The distance from the comb is no less than the distance from the ring rotor to the cell.

EFFECT: improved design.

3 cl, 4 dwg

Description

Technical field

The invention relates to labyrinth seals using fine-mesh cells in axial turbines with a large temperature difference in the working environment. The preferred field of application of the invention are steam turbines.

State of the art

Closest to the proposed solution, the honeycomb seal disclosed in the drawing and in the description of the invention according to patent RU No. 2150627. Axial clearances in seals are selected taking into account the expansion of the rotor and cylinder when starting the turbine, during steady state and when stopping, including emergency (V. P. Bannik and M. A. Sluchaev “Installation of steam turbines”, 1954).

Disclosure of invention

The invention solves the problem of optimizing axial and radial clearances of sealing elements to increase its effectiveness in a wide range of operating modes.

The labyrinth seal includes an annular turbine rotor ridge mounted with axial clearances between the annular stator ridges. In the stator, fine-mesh honeycombs are installed. Honeycombs are installed between the annular ridges of the stator with an annular radial clearance relative to the annular ridge of the rotor.

According to the invention, the fine-mesh cells are made of a material with a hardness substantially lower than the hardness of the material of the rotor ridge. The honeycombs are installed with an overlap preventing the flow of steam or gas through the radial clearance in the axial direction. The distance from the annular ridge of the rotor to each of the edges of the fine-mesh cells in a direction approximately parallel to the axis of the rotor in the idle state of the turbine at approximately equal rotor and stator temperatures is from 40% to 60% of the cell width. The distance from the annular ridge of the rotor to each of the annular ridges of the stator is not less than the distance from the annular ridge of the rotor to the corresponding edge of the fine-mesh cells.

The labyrinth seal of the band of the turbine stage may be provided with steam or gas turbulization means made in the form of a sharp edge of the ridge of the rotor band with the possibility of separation of the flow during its flow and restrict its flow through the seal.

The labyrinth seal of the turbine shaft may contain several spaced apart sections of fine-meshed honeycomb spaced along the rotor axis, covering the corresponding rotor combs. In this case, the cylindrical surface of the rotor between each of its two ridges can be located relative to the annular ridge of the stator with an annular radial clearance separating the expansion ring cavities formed by the stator, rotor and their annular ridges. Each of the annular ridges of the stator is made of a material with a hardness substantially lower than the hardness of the material of the cylindrical surface of the rotor.

Brief Description of the Drawings

The invention is further illustrated by specific examples of its implementation with reference to the accompanying drawings, which depict:

Figure 1 - supra-part of the steam turbine, a longitudinal section;

Figure 2 - node A of figure 1 on an enlarged scale;

Figure 3 - node B of figure 1 on an enlarged scale;

Figure 4 - node In figure 1 on an enlarged scale.

Embodiments of the Inventions

The following describes possible embodiments of the invention as applied to a steam turbine. The turbine is located between the input 51 and output 52 devices. The turbine rotor 11 includes a shaft 41 with a large number of stages, the working blades of which are provided with bandages 38, 39, 40. The working blades of the stages are separated by guide devices on the diaphragms.

The labyrinth seal includes annular ridges 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 of the turbine rotor 11. The ridges of the rotor 11 are installed with axial gaps between the annular ridges of the stator: ridge 2 between the ridges 12 and 13 (Figure 2), ridge 3 between the ridges 13 and 14 (Figure 2), ridge 5 between the ridges 15 and 16 (Figure 3) ridge 6 between ridges 17 and 18 (FIG. 3), ridge 7 between ridges 19 and 20 (FIG. 3), ridge 8 between ridges 21 and 22 (FIG. 3), ridge 9 between ridges 23 and 24 (FIG. 4), ridge 10 between ridges 25 and 26 (Figure 4).

Small cell honeycombs 28, 29, 30, 31, 32, 33, 34, 35, 36, 37 are installed in the stator: cells 29 between ridges 12 and 13, cells 30 between ridges 13 and 14, cells 32 between ridges 15 and 16, cells 33 between ridges 17 and 18, honeycomb 34 between ridges 19 and 20, honeycomb 35 between ridges 21 and 22, honeycomb 36 between ridges 23 and 24, honeycomb 37 between ridges 25 and 26. Honeycombs are installed with an annular radial clearance relative to the corresponding annular rotor ridge . The fine-mesh cells are made of material with a hardness less than the hardness of the material of the rotor flanges and are installed with the possibility of restricting the flow of steam or gas through the radial clearance in the axial direction.

The turbine rotor is set so that the ridges of the rotor brace are relative to the stator ridges at a distance of 40% to 60% of the width of the cells. This is due to the difference in temperature and expansion coefficients of the rotor and turbine body parts. Both when starting the turbine and when it stops, the rotor has a greater axial displacement both in the positive and in the negative direction from the thrust bearing.

In the idle state of the turbine at approximately equal temperatures of the rotor and stator, the distance from the annular ridge of the rotor to each of the edges of the fine-mesh cells in a direction approximately parallel to the axis of the rotor is from 40% to 60% of the width of the cells. The width of the cells is equal to the largest difference in the linear expansions of the rotor and stator in the same direction when the turbine enters the operating mode or when it stops. The distance from the annular ridge of the rotor to each of the annular ridges of the stator is not less than the distance from the annular ridge of the rotor to the corresponding edge of the fine-mesh cells.

The labyrinth seal of each of the bandages 38, 39 and 40 of the turbine stage is provided with means for turbulizing steam or gas. This tool is made in the form of a sharp edge of the corresponding crest of the rotor brace. The sharp edge of the ridge provides separation of the flow during its flow and limitation of the flow of gas or steam through the seal.

As shown in figure 2, the labyrinth seal of the turbine rotor along the shaft 41 contains several spaced apart sections of fine-meshed honeycomb spaced along the rotor axis, covering the corresponding rotor ridges. The cylindrical surface of the rotor shaft between each two ridges is located relative to the annular ridge of the stator with an annular radial clearance separating the expansion annular cavities 42, 43, 44, 45, 46, 47. The cavities are formed by the stator, rotor and their annular ridges.

Each of the stator annular ridges is made of a material with a hardness substantially less than the hardness of the material of the cylindrical surface of the rotor shaft.

Claims (3)

1. A labyrinth seal comprising an annular turbine rotor ridge mounted with axial gaps between the stator annular ridges, fine-mesh cells installed in the stator between its annular ridges with an annular radial clearance with respect to the annular rotor ridge, characterized in that the fine-mesh honeycombs are made of material with hardness less than the hardness of the material of the rotor ridge and installed with the possibility of limiting the flow of steam or gas through the radial clearance in the axial direction, while not working In the state of a turbine with approximately equal rotor and stator temperatures, the distance from the annular rotor ridge to each of the edges of the fine-mesh cells in a direction approximately parallel to the rotor axis is 40-60% of the honeycomb width, and the distance from the annular rotor ridge to each of the annular stator ridges does not less than the distance from the annular ridge of the rotor to the corresponding edge of the fine-mesh cells. 2. The labyrinth seal according to claim 1, characterized in that it is provided with steam or gas turbulization means, which is made in the form of a sharp edge of the rotor ridge with the possibility of separation of the flow during its flow and limiting its flow through the seal. 3. The labyrinth seal according to claim 1, characterized in that it contains several sections of fine-mesh cells spaced along the axis of the rotor, covering the respective rotor ridges, the cylindrical surface of the rotor between each of its two ridges is located relative to the annular ridge of the stator with an annular radial clearance separating the expansion ring cavities formed by the stator, rotor and their annular ridges, each of the annular stator ridges is made of a material with a hardness less than the hardness of the cylinder material rotor surface.

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