JPH09324602A - Double step balance piston steam chamber for steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double step balance piston steam chamber with which axial length of a steam turbine is reduced and a compact structure is attained. SOLUTION: An airtight ring 11 having a half divided structure is arranged in a circular steam chamber formed between a casing 2 and a nozzle chamber 3 on a low pressure side of a labyrinth ring 7. The circular steam chamber is partitioned into an outer steam chamber 9 and an inner steam chamber 10 in a diameter direction. High pressure balance steam is introduced to the outer steam chamber 9 through plural balance steam conduction holes formed on the labyrinth ring 7, while low pressure balance steam is enclosed inside the inner steam chamber 10, and thereby a double step balance piston steam chamber is formed. Axial length of a turbine is thus reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stage balanced piston steam chamber of a horizontal two-divided steam turbine.

[0002]

2. Description of the Related Art FIG. 5 is a longitudinal sectional view showing a two-stage balanced piston steam chamber of a conventional horizontal two-division steam turbine.
The rotor 1 is housed in a casing 2, and the casing 2 includes a nozzle chamber 3 and a nozzle 4. A labyrinth ring 7, a gland packing 8 and first-stage labyrinth fins 20a and 2 are provided between the rotor 1 and the casing 2.
It has a labyrinth fin 20b at the stage. The main steam enters from the main steam inlet 6, passes through the nozzle 4, and is injected to the impulse blade 5 and flows rightward and is injected to the reaction blade. The reaction turbine has a pressure difference before and after the moving blades, but the rotor receives a considerable amount of axial steam thrust as the sum of the pressures at each stage.
As a countermeasure against this, a balance piston is provided in the direction opposite to the moving blades to create a thrust in the direction opposite to the steam flow and cancel the steam thrust applied to the row of moving blades. As shown in FIG. 5, annular high-pressure balanced steam chambers 14 and low-pressure balanced steam chambers 15 are provided on both sides of the labyrinth ring 7.
The steam is guided to the high pressure balanced steam outlet nozzle 14a and the low pressure balanced steam outlet 15a to generate a balance force in a direction opposite to the thrust applied to the blade row.

[0003]

If the two-stage balanced piston steam chamber is an annular steam chamber arranged in two axial directions, the length of the casing 2 in the axial direction increases. Since the balance piston portion has a high temperature and uses expensive cast and forged steel, increasing the axial length increases the cost of the turbine.

An object of the present invention is to provide a two-stage balanced piston steam chamber having a compact structure by shortening the axial length of the steam turbine.

[0005]

According to the present invention, a labyrinth ring having a two-stage labyrinth fin is mounted in a casing, and a two-stage balanced piston is formed in front of and behind the labyrinth fin. In the steam turbine of, in the annular steam chamber formed on the low pressure side of the labyrinth ring between the casing and the nozzle chamber,
An airtight ring having a two-part structure is provided to partition the annular steam chamber into an outer steam chamber and an inner steam chamber in the radial direction, and the outer steam is passed through a plurality of balance steam outlet holes formed in the labyrinth ring. The high-pressure balanced steam on the steam outlet side of the first-stage labyrinth fin was introduced into the chamber, and the low-pressure balanced steam on the steam outlet side of the second-stage labyrinth fin was confined to the inner steam chamber. It serves as a high-pressure balanced steam chamber, and the inner steam chamber serves as a low-pressure balanced steam chamber. Moreover, since the outer steam chamber is arranged on the outer diameter side of the inner steam chamber, the axial lengths of the cast steel casing and the rotor are shortened, and the size is made compact, so that the cost can be reduced.

According to the present invention, a labyrinth ring having two-stage labyrinth fins is mounted in the casing, and a horizontal two-division structure steam turbine in which two-stage balancing pistons are formed in front of and behind the labyrinth fin is used as a casing. And the labyrinth ring, a ring-shaped steam chamber formed on the low-pressure side of the labyrinth ring is provided with an airtight ring with a two-part structure, and the ring-shaped steam chamber is divided into an outer steam chamber and an inner steam chamber. The high-pressure balanced steam on the steam outlet side of the first-stage labyrinth fin through the plurality of balanced steam discharge holes formed in the labyrinth ring and directed to the outer steam chamber, and to the inner steam chamber. Since the low pressure balanced steam on the steam outlet side of the labyrinth fin of the first stage is confined, the outer steam chamber functions as a high pressure balanced steam chamber, Air chamber is the role of the low-pressure balance steam chamber. Moreover, since the outer steam chamber is arranged on the outer system side of the inner steam chamber, the axial lengths of the cast steel casing and the rotor are shortened to be compact and the cost can be reduced.

[0007]

Embodiment 1 FIG. 1 is a longitudinal sectional view showing an embodiment of a two-stage balanced piston steam chamber in which an annular steam chamber is partitioned between a casing and a nozzle chamber of the present invention. 2 is a II-II sectional view of FIG. 1, and FIG. 3 is an enlarged sectional view of the airtight ring of FIG. The arrows show the flow of steam. 1, the same parts as those in FIG. 5 are designated by the same reference numerals. In the annular steam chamber formed on the low pressure side of the labyrinth ring 7 between the casing 2 and the nozzle chamber 3,
An airtight ring 11 having a two-part structure is provided to partition the annular steam chamber into an outer steam chamber 9 and an inner steam chamber 10 in the radial direction. The airtight ring 11 is fitted in the two casing grooves 12 and the one nozzle chamber groove 13, and the radial airtight surface 18 and the axial airtight surface 19 form the outer steam chamber 9 and the inner steam chamber 1.
It is kept airtight with 0. In FIG. 2, the labyrinth ring 7 has a plurality of high-pressure balanced steam outlet holes 17. The high-pressure balanced steam on the steam outlet side of the labyrinth fin 20a of the first stage is guided to the outer steam chamber 9 through the plurality of balance steam derivation holes 17 formed in the labyrinth ring 7, and to the inner steam chamber 10 of the second stage. The low-pressure balanced steam on the steam outlet side of the labyrinth fin 20b is trapped. The steam in the outer steam chamber 9 is the high pressure balanced steam outlet 14 below the turbine.
The steam in the inner steam chamber 10 is guided to the low pressure balanced steam outlet 15a below the turbine. The outer steam chamber 9 functions as a high pressure balanced steam chamber, and the inner steam chamber 10 functions as a low pressure balanced steam chamber. According to the present invention, the axial lengths of the cast steel casing 2 and the rotor 1 are shortened,
The turbine can be made compact.

Embodiment 2 FIG. 4 is a longitudinal sectional view showing an embodiment of a two-stage balanced piston steam chamber for partitioning an annular steam chamber between a casing and a labyrinth ring according to the present invention. FIG. Shows a reaction turbine without. The arrows show the flow of steam. The labyrinth ring 7 is provided between the casing 2 and the labyrinth ring 7.
The annular steam chamber formed on the low-pressure side is provided with an airtight ring 11 having a two-part structure to partition the annular steam chamber into an outer steam chamber 9 and an inner steam chamber 10 in the radial direction. The airtight ring 11 is
It is fitted in the two casing grooves 12 and the one nozzle chamber groove 13, and the radial steamtight surface 18 and the axial airtight surface 19 keep the outer steam chamber 9 and the inner steam chamber 10 airtight. The labyrinth ring 7 is provided with a plurality of high pressure balanced steam outlet holes 17 as shown in FIG. A plurality of balanced steam outlet holes 1 formed in the labyrinth ring 7.
Labyrinth fin 20a of the first stage to the outside steam chamber 9 through 7
The high-pressure balanced steam on the steam outlet side is confined to the inner steam chamber 10 and the low-pressure balanced steam on the steam outlet side of the second-stage labyrinth fin 20b is confined. The steam in the outer steam chamber 9 is guided to the high pressure balanced steam outlet 14a below the turbine, and the steam in the inner steam chamber 10 is guided to the low pressure balanced steam outlet 15a below the turbine. The outer steam chamber 9 functions as a high pressure balanced steam chamber, and the inner steam chamber 10 functions as a low pressure balanced steam chamber. According to the present invention, the axial length of the cast steel casing 2 and the rotor 1 can be shortened, and the turbine can be made compact.

[0009]

According to the present invention, the annular steam chamber formed between the casing and the nozzle chamber on the low-pressure side of the labyrinth ring is provided with the air-tight ring having a two-part structure, and the annular steam chamber is removed from the outside. The high-pressure balanced steam on the steam outlet side of the first-stage labyrinth fin is guided to the outer steam chamber through a plurality of balance steam discharge holes formed in the labyrinth ring and partitioned in the radial direction into the steam chamber and the inner steam chamber. At the same time, the low-pressure balanced steam at the steam outlet side of the second labyrinth fin was confined in the inner steam chamber, so the outer steam chamber functions as the high-pressure balanced steam chamber and the inner steam chamber functions as the low-pressure balanced steam chamber. And a two-stage balanced piston steam chamber is formed,
Moreover, since the outer steam chamber and the inner steam chamber are partitioned in the radial direction, the axial length of the turbine is shortened, and the turbine can be made compact and the cost can be reduced. Further, since the axial length is shortened, it is also useful for improving the reliability of the rotor.

According to the present invention, between the casing and the labyrinth ring, the annular steam chamber formed on the low-pressure side of the labyrinth ring is provided with the airtight ring of the two-part structure so that the annular steam chamber is not exposed. The high-pressure balanced steam on the steam outlet side of the first-stage labyrinth fin is divided into the steam chamber and the inner steam chamber in the radial direction, and is guided to the outer steam chamber through a plurality of balance steam discharge holes formed in the labyrinth ring. ,
Since the low-pressure balanced steam on the steam outlet side of the labyrinth fin of the second stage is confined in the inner steam chamber, the outer steam chamber serves as the high-pressure balanced steam chamber, and the inner steam chamber serves as the low-pressure balanced steam chamber. Since a two-stage balanced piston steam chamber is formed and the outer steam chamber and the inner steam chamber are partitioned in the radial direction, the axial length of the turbine is shortened,
It can be made compact and cost can be reduced. Further, since the axial length is shortened, it is also useful for improving the reliability of the rotor.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a two-stage balanced piston steam chamber according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

3 is an enlarged cross-sectional view of the airtight ring of FIG.

FIG. 4 is a vertical sectional view of a two-stage balanced piston steam chamber according to a second embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a two-stage balanced piston steam chamber of a conventional horizontal two-split steam turbine.

[Explanation of symbols]

 1 rotor 2 casing 3 nozzle chamber 4 nozzle 5 impulse blade 6 main steam inlet 7 labyrinth ring 8 gland packing 9 outer steam chamber 10 inner steam chamber 11 airtight ring 12 casing groove 13 nozzle chamber groove 14 high pressure balanced steam chamber 14a high pressure balanced steam outlet Nozzle 15 Low pressure balanced steam chamber 15a Low pressure balanced steam outlet nozzle 16 Drain outlet 17 High pressure balanced steam outlet hole 18 Radial airtight surface 19 Axial airtight surface 20a 1st labyrinth fin 20b 2nd labyrinth fin

Claims (2)

[Claims] 1. A steam turbine having a horizontal two-division structure in which a labyrinth ring having two-stage labyrinth fins is mounted in a casing, and two-stage balancing pistons are formed before and after the labyrinth fin. The annular steam chamber formed on the low pressure side of the labyrinth ring between and is provided with an airtight ring having a two-part structure, and the annular steam chamber is radially partitioned into an outer steam chamber and an inner steam chamber, In addition, the high-pressure balanced steam on the steam outlet side of the first-stage labyrinth fin is guided to the outer steam chamber through a plurality of balanced steam outlet holes formed in the labyrinth ring, and the second-stage labyrinth to the inner steam chamber. A two-stage balanced piston steam chamber for a steam turbine, which is characterized by confining low-pressure balanced steam on the steam outlet side of the fin. 2. A steam turbine having a horizontal two-division structure in which a labyrinth ring having two-stage labyrinth fins is mounted in a casing, and two-stage balanced pistons are formed in front of and behind the labyrinth fin. In between, an annular steam chamber formed on the low pressure side of the labyrinth ring is provided with an airtight ring having a two-part structure, and the annular steam chamber is partitioned into an outer steam chamber and an inner steam chamber in a radial direction, In addition, the high-pressure balanced steam on the steam outlet side of the first-stage labyrinth fin is guided to the outer steam chamber through a plurality of balanced steam outlet holes formed in the labyrinth ring, and the second-stage labyrinth to the inner steam chamber. A two-stage balanced piston steam chamber for a steam turbine, which is characterized by confining low-pressure balanced steam on the steam outlet side of the fin.