JPH07208107A - Reaction type steam turbine - Google Patents

Abstract

PURPOSE:To reduce the weight of a reaction type steam turbine, and also improve its inside efficiency. CONSTITUTION:The stationary blade 22 of a reaction step is formed integratedly with a partition plate 23 which is divided into two parts on a center surface, and also the center surface of the partition plate 23 is maintained to the outer part casing 1 and an inner part casing of a steam turbine. The blade train of a reaction step is constituted so as to set a reaction degree to 35 to 42 % at the time of constant operation of the steam turbine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reaction-type steam turbine, and more particularly to a reaction-type steam turbine whose weight is reduced.

[0002]

2. Description of the Related Art First, the structure of a conventional reaction type steam turbine will be described with reference to FIGS. FIG. 3 is a partial vertical cross-sectional view of a high-pressure turbine of a conventional large-capacity steam turbine taken along the rotor direction, and FIG. 4 is a cross-sectional view taken in the direction of arrow B in FIG.

As shown in these figures, in the conventional high-pressure turbine, a rotor 4 is located at the center of a steam chamber 3 surrounded by an outer casing 1 and an inner casing 2, and the rotor 4
Through the main steam inlet pipe, not shown,
A nozzle chamber 5 into which high temperature, high pressure main steam from the boiler is introduced is provided. A nozzle plate 6 is attached to the nozzle chamber 5 on the steam chamber 3 side to form a steam outlet 7. Impulse blades 8 forming a speed control stage are implanted in the rotor 4 so as to face the steam outlet 7 of the nozzle plate 6. Further, the rotor 4 is provided with a large number of reaction blades 9 implanted in each disk portion.
On the other hand, each of the stationary blades 10 forming a reaction stage is provided.

These vanes 10 are the first blade ring 1
The first blade ring 11 is divided into a group implanted in 1 and a group implanted in the second blade ring 12.
Is attached to the inner casing 2 and the second blade ring 12 is attached to the outer casing 1. The center of the first blade ring 11 is held in the inner casing 2 by the center key 13, and the center of the second blade ring 12 is held in the outer casing 1 by the center key 14. Therefore, the vane 1
0 is a blade ring 1 as shown in FIG.
It is in the form of being hung on 1 and 12.

In the high-pressure turbine configured as described above, the high-temperature, high-pressure main steam introduced into the nozzle chamber 5 from a boiler (not shown) or the like flows from the steam outlet 7 into the impulse blades 8 for work. After that, the steam is accelerated by the reaction stage stationary vanes 10 and sequentially worked by the reaction vanes 9, and the steam that has worked and has its temperature and pressure lowered is exhausted at high pressure.

[0006]

In the conventional turbine, since the center of the stationary blade of the reaction stage is held by the blade ring, it is difficult to align the core of the stationary blade 10 with the rotor 4. However, there is a problem that the structure of the turbine itself becomes extremely large.

Further, during warm-up operation such as startup of the steam turbine, the rotor 4 is provided with the blade rings 11 and 12.
It will be warmed up before. Since the stationary blade 10 has a structure suspended from the blade rings 11 and 12, the stationary blade 10 is warmed before the blade rings 11 and 12. Therefore, in order to prevent the rotating part from coming into contact with the stationary part during a transitional period such as startup, between the tip of the stationary blade 10 and the rotor 4 forming the reaction stage, and between the tip of the moving blade 9 and the blade ring 11. , 12, it was necessary to provide a considerable gap S (see FIG. 3) in advance. Due to this gap S, the clearance during steady operation cannot be reduced, which causes a leakage loss at the blade tip and causes a decrease in internal efficiency.

More generally, the total adiabatic heat drop h at the reaction stage
a is a reaction degree ρ of approximately 5 so that the adiabatic heat drop hb in the moving blade is substantially equal to the adiabatic heat drop hc in the stationary blade.
It is designed to be 0%. Here, the reaction degree ρ is expressed by the following mathematical expression 1.

[Mathematical formula-see original document] ρ = hb / ha At this time, the speed ratio, that is, the ratio of the absolute speed of steam at the inlet of the stationary blade to the rotational speed of the moving blade, or the relative speed of steam at the moving blade inlet and the rotation of the moving blade. The ratio to the speed is about 90% in each case. Therefore, although the blade element efficiency of the reaction stage is higher than that of the impulse stage, there is a problem that the number of reaction stages becomes large.

The present invention has been made in order to solve the problems of the prior art, and an object thereof is to reduce the weight of the reaction steam turbine and to improve the internal efficiency.

[0010]

In order to solve the above-mentioned problems, the present invention provides a recoil type steam turbine, in which a stationary blade of a reaction stage is integrally formed on a partition plate which is vertically divided into two parts at a center plane. At the same time, the center plane of the partition plate is held by the outer casing or the inner casing of the steam turbine.

[0011]

[Operation] According to the above means, the partition plate has a structure for supporting the center, and the center of the stationary blade is held even without the blade ring. Then, during a transitional period such as when the turbine is started, the partition plate expands outward, so the gap for preventing contact between the rotating part and the stationary part can be made narrower than before, and as a result, The leakage of steam from the blade tip can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a reaction type steam turbine according to the present invention will be described in detail below with reference to FIGS. 1 is a partial vertical cross-sectional view of a high-pressure turbine of a large-capacity steam turbine to which the present invention is applied, taken along the rotor direction, FIG. 2 is a cross-sectional view taken in the direction of arrow A in FIG. 1, and FIGS. Since the same parts as those shown in FIG.
Description of that part is omitted.

As shown in these figures, the steam chamber 3 is formed so as to be surrounded by the outer casing 1, and the rotor 4 is located at the center thereof. A nozzle chamber 5 is provided so as to surround the rotor 4, and to the nozzle chamber 5,
High-temperature, high-pressure main steam from a boiler (not shown) is introduced through the main steam inlet pipe 21. A nozzle plate 6 is attached to the steam chamber 3 side of the nozzle chamber 5 to form a steam outlet 7, and a speed control stage is formed on the rotor 4 so as to face the steam outlet 7 of the nozzle plate 6. Impulse wings 8 are implanted. Further, the rotor 4 is provided with a large number of reaction blades 9 implanted in each disk portion.

Each of the reaction blades 9 is provided with a stationary blade 22 which forms a reaction stage.
The partition plate 23 is formed integrally with the partition plate 23, and the partition plate 23 is fitted in the outer casing 1. The partition plate 23 has a structure in which the center plane is divided into upper and lower halves. By holding the center plane in the outer casing 1, the center of the vane 22 is held without providing a blade ring. There is.

Although not shown, the horizontal surface of the partition plate 23 is combined with a key to keep airtightness. Further, a labyrinth 24 is embedded in a portion of the partition plate 23 facing the rotor 4 so that the leaked steam from the gap is minimized. Similarly, the reaction blade 9
A spacer 26 having a labyrinth 25 is provided on the inner wall side of the outer casing 1 facing the tip of each of the stationary blades 22 of each reaction stage.
It is provided between the partition plates 23 forming the above so as to minimize the leaked steam at the tip of the reaction blade 9.

Next, in the present invention, during rated operation of the steam turbine, the reaction degree ρ, that is, the ratio of the adiabatic heat drop hb in the moving blade and the total adiabatic heat drop ha in the reaction stage shown in the above mathematical expression 1 Is designed to be 35 to 42%. That is, since the design is performed by lowering the ratio (speed ratio) of the rotation speed of the blade in the reaction stage and the steam velocity of the stationary blade or the blade inlet, it is possible to increase the adiabatic heat drop hb required for each stage. As a result, the number of reaction stages as a whole can be reduced. Therefore, it is possible to improve efficiency and reduce manufacturing cost.

It is needless to say that the present invention is not limited to the above-mentioned one embodiment, and can be variously modified and carried out without departing from the scope of the invention. For example, the partition plate 23 integrally formed with the stationary blades 22 may be fitted into the inner casing 2 (see FIG. 3).

[0018]

As described in detail above, according to the present invention,
In the reaction-type steam turbine, the number of reaction stages can be reduced, and since the blade ring is unnecessary, the weight of the turbine can be reduced, and the structure is simplified, so that maintenance is easy. For example, 350 MW
When the present invention is applied to a turbine for a 50 Hz generator, the weight of the high / intermediate pressure element is approximately one half that of the conventional turbine. Further, it is possible to reduce the leakage of steam from the blade tips and improve the internal efficiency of the turbine by about 1%.

[Brief description of drawings]

FIG. 1 is a partial vertical cross-sectional view of a high-pressure turbine of a large-capacity steam turbine to which the present invention is applied, taken along a rotor direction.

FIG. 2 is a sectional view taken in the direction of arrow A in FIG.

FIG. 3 is a partial vertical cross-sectional view of a high-pressure turbine of a conventional large-capacity steam turbine taken along the rotor direction.

FIG. 4 is a sectional view taken along the arrow B in FIG.

[Explanation of symbols]

 1 Outer Casing 4 Rotor 5 Nozzle Chamber 6 Nozzle Plate 7 Steam Outlet 8 Impulse Blade 9 Reaction Blade 21 Main Steam Inlet Pipe 22 Stator Blade 23 Partition Plate 24 Labyrinth 25 Labyrinth 26 Spacer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiro Tarutani 2-1-1, Niihama, Arai-cho, Takasago-shi, Hyogo Mitsubishi Heavy Industries Takasago Plant

Claims (2)

[Claims] 1. A stator blade of a reaction stage is integrally formed with a partition plate which is vertically divided into two parts with a center plane, and the center plane of the partition plate is held by an outer casing or an inner casing of a steam turbine. Characteristic reaction type steam turbine. 2. The reaction-type steam turbine according to claim 1, wherein the blade row of the reaction stage is configured such that the degree of reaction is 35 to 42% during rated operation of the steam turbine. .