RU2605876C1 - Steam turbine diaphragm - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: diaphragm for double-tier low pressure cylinder (LPC) lower tier first stage. Diaphragm is made double-tier, wherein in lower part steam turbine stage typical diaphragm is arranged, and in upper tier aerodynamic filter is installed. Filter consists of radially arranged flat perforated plates, continuously arranged around lower tier diaphragm external rim outer circumference with angle pitch, not exceeding 5°. Engineering problem, solved by disclosed diaphragm, consists in non-uniform inlet velocities field aligning, reduction of pressure pulsations amplitudes in steam flow before LPC upper tier first stage.

EFFECT: technical result, achieved due to disclosed diaphragm installation on double-tier LPC first stage consists in solving problems, associated with its fixture in LPC housing, as well as in upper tier blade systems operation under conditions of velocities uniform distribution in circumferential direction.

1 cl, 2 dwg

Description

The invention relates to the field of power engineering and is associated with the creation of a new two-tiered low-pressure cylinder with an increased maximum passage of steam into the condenser.

The design feature of the cylinder in question is that the number of pressure steps in the upper tier is always lower than the number of steps in the lower tier [1] (Zaryankin AE, Arianov SV, Zaryankin VA Flow part of a steam turbine. Patent for invention No. 2296224 RU with priority dated June 22, 2006 BI No. 9 03/27/2007), in connection with this, serious problems arise with the organization of steam supply to the first stage of the upper tier and with the fastening of the lower tier diaphragm in the low-pressure cylinder housing.

Known diaphragms of the first stage of the low pressure cylinder consist of the body of the diaphragm and the rim of the diaphragm, between which nozzle vanes of the turbine stage are installed. The diaphragms have a horizontal connector and are installed in the holder of the diaphragm connected with the cylinder body [2] (Trukhny AD Stationary steam turbines. M. Energoatomizdat. 1990).

The main disadvantage of such diaphragms, when used in the first stage of a two-tier low pressure cylinder, is associated with the problems that arise when they are installed in the diaphragm cage. This is explained by the fact that in the upper tier the number of steps is less than in the lower, and the first step of the upper tier is shifted relative to the first step of the lower tier. It is also worth noting that when installing such apertures, the non-uniformity of the velocity field in front of the nozzle apparatus of the first stage of the upper tier greatly increases.

The technical problem solved by the proposed diaphragm of a steam turbine is to equalize the uneven input velocity field and reduce the amplitudes of the pressure pulsations in the steam stream before the first stage of the upper stage of the low-pressure cylinder.

The technical result obtained due to the proposed diaphragm is to solve the problems associated with its fastening in the case of a two-tier low-pressure cylinder, as well as the operation of the upper tier vanes under conditions of uniform distribution of speeds in the circumferential direction and is achieved by the fact that the known diaphragm, mainly for the first stage of the two-tier low-pressure cylinder, containing a disk, an outer contour of the lower tier, nozzle blades of the first stage of the lower tier, an outer contour of the upper tier and perforated plates Astin, is performed in two tiers, with the usual diaphragm of the steam turbine stage located in the lower part, and in the upper tier an aerodynamic filter consisting of flat radially mounted perforated plates continuously located along the entire outer circumference of the outer contour of the lower tier aperture with an angular step not exceeding 5 °.

The list of drawings:

In FIG. 1 shows the design of the diaphragm for the first stage of a two-tier LPC, which is a two-tier structure.

In FIG. 2 for reference is a longitudinal section of a two-tier low pressure cylinder with the proposed two-tier diaphragm of the first stage.

The lower tier of the diaphragm in question consists of a disk 1, an outer bypass 2, between which nozzle blades of the first stage of the lower tier 3 are installed. Between the outer bypass of the upper tier 4 and the outer bypass of the lower tier 2 with an angular pitch not exceeding 5 °, perforated plates 5 are radially mounted which are essentially aerodynamic filters.

The nozzle vanes of the lower tier 3 and the perforated plates 5 of the upper tier are rigidly connected to the disk 1 and the contours 2 and 4, thereby forming a single rigid, non-separable structure with a horizontal connector, like all conventional diaphragms. The lower and upper halves of the diaphragm are mounted in a diaphragm cage connected to the low-pressure cylinder housing.

The proposed diaphragm of a steam turbine for a two-tier LPC works as follows. Most of the steam flowing through the lower tier expands in the channels of the nozzle gratings 3, the other part of the steam flowing through the upper tier of the diaphragm interacts with an aerodynamic filter having a low aerodynamic drag and not letting large discrete vortex formations pass to the input section of the nozzle apparatus of the first stage of the upper stage tier. The perforation holes on the plates suppress the circumferential unevenness of the steam flow and practically reduce the shear forces acting on the plates to zero when the steam velocity vectors deviate from the axial direction.

Bibliography

1. Zaryankin A.E., Arianov SV., Zaryankin V.A. Flowing part of a steam turbine. Patent for invention No. 2296224 RU with priority dated 06/22/2006, BI No. 9 03/27/2007.

2. Trukhny A.D. Stationary steam turbines. M. Energoatomizdat, 1990.

Claims (1)

A diaphragm, mainly for the first stage of a two-tier low-pressure cylinder, comprising a disk, an outer contour of the lower tier, nozzle blades of the first stage of the lower tier, an outer contour of the upper tier and perforated plates, characterized in that it is made of two-tier, with the usual diaphragm of the step being located in the lower part steam turbine, and in the upper tier there is an aerodynamic filter consisting of flat radially mounted perforated plates continuously located throughout the entire outer circumference the outer circumference of the diaphragm of the lower tier with an angular step not exceeding 5 °.

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