JP2890907B2 - Steam turbine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-flow steam turbine having a labyrinth packing at a portion where a rotor penetrates a casing to prevent leakage of high-pressure and high-temperature steam flowing into the casing.

[0002]

2. Description of the Related Art FIG. 2 shows a labyrinth packing provided at a penetrating portion through which a rotor penetrates a casing so that high-pressure and high-temperature steam flowing into the casing and performing expansion work at a blade stage in the casing does not leak. A single-flow steam turbine having a double casing structure is known. In FIG. 2, the rotor 1 includes a rotor blade (not shown) and a balance piston 1a. The inner casing 2 includes a stationary blade (not shown), and forms a rotor blade and a high-pressure blade stage 3 to surround the rotor 1. A labyrinth ring 4 of the inner casing 2 and a balance piston 1a are provided in a penetrating portion where the rotor 1 penetrates the inner casing 2.
And a labyrinth packing 5 is provided between them. Reference numeral 6 denotes a steam inlet passage through which steam flows into the high-pressure blade stage 3. The stationary blade holder 8 includes stationary blades (not shown), and forms a rotor blade and a low-pressure blade stage 9 to surround the rotor 1.

[0003] The outer casing 10 surrounds the inner casing 2 and the vane holder 8, and the rotor 1 is connected to the outer casing 1 by the outer casing 1.
The holes 11 and 12 for shaft sealing steam
The high-pressure gland packing 15 and the low-pressure gland packing 16 are provided between the high-pressure gland ring 13 and the low-pressure gland ring 14 and the rotor 1, respectively. Also, a steam inlet 17 provided in the outer casing 10
Is connected to the steam inlet passage 6 of the inner casing 2. Reference numeral 18 denotes an exhaust port for discharging steam discharged from the low-pressure blade stage 9.

The leaked steam supply pipe 20 is a pipe for guiding steam leaked from the labyrinth packing 5 to a middle portion 19 of the low-pressure gland packing 16, and has a water injection device 21 on the way.

[0005] With such a structure, the high-pressure and high-temperature steam flowing into the inner casing 2 through the steam inlet 17 and the steam inlet passage 6 performs expansion work in the high-pressure blade stage 3 and the low-pressure blade stage 9 to cause the rotor 1 to rotate. The rotating steam generates power, and the exhaust steam discharged from the low-pressure blade stage 9 is sent out from the exhaust port 18 to the outside.

At this time, the steam flowing into the inner casing 2 is prevented from leaking out of the inner casing 3 by the labyrinth packing 5, but the steam room 22 between the labyrinth packing 5 and the balance piston 1a and the outer casing 10 is prevented. The high-pressure gland packing 15 prevents the leaked steam from leaking out of the outer casing 10. Similarly, the low-pressure gland packing 16 prevents low-pressure exhaust steam flowing to the exhaust port 18 from leaking out of the outer casing 10.

Here, the steam leaked from the labyrinth packing 5 into the steam chamber 22 flows through the leaked steam supply pipe 20 to the middle part 19 of the low-pressure gland packing 16 which is a low-pressure steam part, and is located on the steam chamber 22 side of the balance piston 1a. The steam pressure of the steam chamber 22 is applied to the piston surface. As a result, a thrust applied to the rotor 1 in the left direction in the figure is generated by the steam pressure applied to the piston surface between the blade stage side of the balance piston 1a and the steam chamber 22 side. This thrust is balanced with the thrust applied to the right in the diagram generated when steam flows through the wing stage and performs expansion work.

The temperature of the high-temperature steam leaked from the labyrinth packing 5 into the steam chamber 22 by the water injection device 21 is reduced by water injection to match the temperature of the steam in the middle portion 19 flowing through the low-pressure gland packing 16 at a low temperature.

[0009]

Since the steam flowing into the labyrinth packing 5 is high-pressure and high-temperature steam flowing into the turbine, the steam leaking from the labyrinth packing 5 also has a high temperature and a high enthalpy. This high enthalpy leaked steam passes through the leaked steam supply pipe 20 and is supplied to the water injection device 21.
Low temperature, low pressure gland packing 16
Enthalpy is not used effectively, and the turbine efficiency is reduced.

Further, since the leaked steam supply pipe 20 has a high temperature leaked steam, it is necessary to use a material which can withstand high temperatures, and furthermore, a water injection device 21 is required to reduce the temperature.
There is a disadvantage that the manufacturing cost is high.

An object of the present invention is to provide a steam turbine capable of improving turbine efficiency by effectively utilizing high-temperature and high-enthalpy steam flowing through a labyrinth packing and further reducing the manufacturing cost of a leaking steam supply pipe. That is.

[0012]

Means for Solving the Problems In order to solve the above,
ADVANTAGE OF THE INVENTION According to this invention, the rotor provided with a rotor blade, the stationary blade which surrounds this rotor, and forms the 1st blade stage into which steam flows in are provided, and the labyrinth packing is provided in the penetration part of the steam inflow side which a rotor penetrates. An inner casing, and an outer casing surrounding the inner casing and having a stationary blade forming a moving blade and a second blade stage downstream of the first blade stage; A high-pressure labyrinth packing portion into which the inflow steam flows, and a labyrinth packing provided separately from the labyrinth packing portion, and the exhaust steam from the first blade stage is disposed between the inner casing and the outer casing. And a low-pressure labyrinth packing portion flowing through the formed steam chamber, and further extracted from an intermediate portion of the high-pressure labyrinth packing portion. Steam piping for guiding the leaking steam to the second blade paragraph shall be provided between the inner casing and the outer casing.

[0013]

[0014]

The labyrinth packing provided on the side where the high pressure and high temperature steam through which the rotor penetrates the inner casing is formed by a high pressure labyrinth packing portion and a low pressure labyrinth packing portion. In the high-pressure labyrinth packing portion, introduction means for guiding the leaked steam from the middle of the high-pressure labyrinth packing portion into which the steam flowing into the turbine flows and leaks to the steam inlet of the second blade stage. By providing a steam pipe from the center to the steam inlet of the second blade stage between the inner casing and the outer casing, high-temperature leaked steam from the center of the high-pressure labyrinth packing is passed through the steam pipe to the second blade stage. Recover and prevent high-temperature leaked steam from leaking into the downstream side. As a result, since the leaked steam having a high enthalpy is collected in the second blade stage to perform work, the work amount (output) inside the turbine increases.

Further, in the low-pressure labyrinth packing portion, the exhaust steam which has been expanded at the first blade stage and has become low temperature flows into the low-pressure labyrinth packing portion through a space between the inner casing and the outer casing. The steam leaking from the low-pressure labyrinth packing portion has a low temperature and flows to a low-pressure steam portion such as a low-pressure gland packing portion.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of a steam turbine according to an embodiment of the present invention. In FIG. 1, the same parts as those in the conventional example of FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted. FIG. 1 differs from the conventional example in the following.

The labyrinth packing 5 comprises a high-pressure labyrinth packing portion 5a and a low-pressure labyrinth packing portion 5b provided separately therefrom. The high-pressure labyrinth packing portion 5a is provided between the high-pressure labyrinth ring 4a and the balance piston 1a of the rotor 1. The low-pressure labyrinth packing portion 5b is provided between the low-pressure labyrinth ring 4b and the balance piston 1a of the rotor 1.

Intermediate part 2 of high-pressure labyrinth packing part 5a
5 through the high-pressure labyrinth ring 4 a to reach the steam inlet of the low-pressure blade stage 9, and the port 26 of the leak-vapor recovery tube 27 directed to the low-pressure blade stage 9 is provided between the inner casing 2 and the outer casing 10. It is provided in the steam chamber 24.

A space 29 between the high-pressure labyrinth ring 5a and the low-pressure labyrinth packing 5b communicates with the exhaust portion 28 of the high-pressure blade stage 3 via the steam chamber 24.

With such a structure, the outer casing 1
The steam that has flowed into the inner casing 2 through the steam inlet 17 of the internal casing 2 and the steam inlet passage 6 of the inner casing 2 performs expansion work in the high-pressure blade stage 3 and the low-pressure blade stage 9 as described above. Is discharged. On the other hand, the steam leaking and flowing through the high-pressure labyrinth packing portion 5a is extracted from the middle portion 25, flows into the low-pressure blade stage 9 from the pipe port 26 via the recovery pipe 27, and performs expansion work.

On the other hand, low-temperature steam discharged from the high-pressure blade stage 3 through the steam chamber 24 between the inner casing 3 and the outer casing 10 flows into the low-pressure labyrinth packing portion 5b from the space 29, and flows into the low-pressure labyrinth ring portion. 5b, and leaks at a low temperature.
After that, it flows into the middle part 19 of the low-pressure gland packing 16.

[0022]

As is apparent from the above description, according to the present invention, the labyrinth packing is composed of a high-pressure labyrinth packing portion and a low-pressure labyrinth packing portion, and the high-pressure labyrinth packing portion has a leakage extracted from an intermediate portion thereof. A recovery pipe is provided to guide the steam to the low-pressure labyrinth stage.The exhaust steam from the high-pressure labyrinth stage flows into the low-pressure labyrinth packing section. Extraction from the middle part, through the recovery pipe, leads to the low-pressure blade stage for expansion work, so turbine efficiency is improved.In the low-pressure labyrinth packing part, low-temperature steam flows due to expansion work at the high-pressure blade stage. Since the steam leaks from the low-pressure labyrinth packing, the temperature of the leaked steam becomes low. Vapor portion leakage steam supply pipe delivering the need not be heat-resistant material, also water injection device for temperature decreasing since unnecessary, there is an effect that manufacturing cost is reduced. Further, in the present invention, a recovery pipe (steam pipe) for guiding leaked steam extracted from an intermediate portion of the high-pressure labyrinth packing portion to the second blade stage is provided between the inner casing and the outer casing, that is, in the steam turbine. Since we will provide
The difference in temperature and pressure between the inside and the outside of the collection tube is reduced, and the collection tube can be made of a material and a structure with low heat resistance and pressure resistance.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a steam turbine according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of a conventional steam turbine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor 2 Inner casing 3 High pressure blade stage 5 Labyrinth packing 5a High pressure labyrinth packing part 5b Low pressure labyrinth packing part 9 Low pressure blade stage 10 External casing 27 Recovery pipe

Claims (1)

(57) [Claims] A rotor having moving blades, a stationary blade surrounding the rotor and forming a first blade stage into which steam flows, and a labyrinth packing provided at a through-portion on a steam inflow side through which the rotor passes. A casing, and an outer casing surrounding the inner casing and including a stationary blade forming a moving blade and a second blade stage downstream of the first blade stage, wherein steam leaking from the labyrinth packing is sent to a low-pressure steam portion. In the leading steam turbine, the labyrinth packing is provided at a high pressure labyrinth packing portion into which the inflow steam flows, and is separated from the labyrinth packing portion, and exhaust steam from the first blade stage is formed between the inner casing and the outer casing. And a low-pressure labyrinth packing that flows in through a steam chamber that has been provided, and a leakage extracted from an intermediate portion of the high-pressure labyrinth packing. Steam turbine, characterized in that the steam pipe for guiding the steam to the second wing paragraph is provided between the inner casing and the outer casing.