JPH0437201Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention prevents high-temperature fluid inside from leaking through a gap in a penetration part in which a turbine axle of a turbine, for example, a steam turbine, rotatably penetrates a casing. The present invention relates to a labyrinth structure of a turbine provided for the purpose of

[Prior art and its problems]

In a turbine, for example, a steam turbine, high-temperature, high-pressure steam is guided to a blade section formed by moving blades installed on the axle and stationary blades installed on the casing, rotates the turbine axle, and performs work, and then is exhausted. be done. In this case, a labyrinth is provided in the gap between the through parts through which the axle rotatably penetrates the casing, and is designed to prevent high-temperature, high-pressure steam from leaking to the outside from the through parts. The prior art will be described below with reference to the drawings.

FIG. 4 is a sectional view of a steam turbine having a conventional turbine labyrinth structure. In the figure 1
is a turbine axle equipped with a moving blade 2a, and a stationary blade 2
A two-split inner casing 3 with b is provided surrounding the turbine axle 1 such that the turbine axle 1 passes through the inner casing 3. The rotor blade 2a and the stationary blade 2b are inserted into each other to form a blade portion 2. Further, the turbine axle 1 is provided with a balance piston 1a. When the steam turbine is a single-flow steam turbine and the blade section 2 is composed of reaction blades, the balance piston 1a absorbs the thrust generated by the flow of steam that flows into the blade section 2 from the outside through an inlet pipe to be described later and performs work. Balance is achieved by the pressure of the inflowing steam applied to 1a. In order to reduce the leakage of the steam that has entered through the gap between the inner casing 3 and the turbine axle 1, a labyrinth ring is installed in the gap between the inner casing 3 and a labyrinth ring (hereinafter referred to as labyrinth ring 1a) that also serves as the balance piston 1a. There are 4. As shown in FIG. 5, the labyrinth 4 consists of fins 4a and 4b embedded in the labyrinth ring 1a and the inner wall 3a of the inner casing 3, respectively, and steam leaks and flows as shown by the arrow. The outer casing 6 which is divided into two parts supports and surrounds the inner casing 3 and also surrounds both ends of the turbine axle 1 with a gap therebetween, thereby allowing the turbine axle 1 to rotate. In the gap of this penetration part, a gland packing 5 is installed in order to prevent the steam in the space between the inner casing 3 and the outer casing 6 from leaking into the atmosphere.
For example, there is a labyrinth. Furthermore, a gland packing piping (not shown) is provided in the middle of the gland packing 5 to control the pressure of the steam flowing inside the gland packing 5 to near atmospheric pressure using a pressure regulating valve, a gland condenser, etc. (not shown), and the steam leaking through the gland packing 5 is prevented. The pressure is controlled to prevent it from leaking into the outside air.

Note that inlet pipes 6a and 3 serve as flow paths passing through the outer casing 6 and the inner casing 3, respectively.
b, which communicates with the inlet chamber 7 between the wing portion 2 and the labyrinth 4. A seal ring 10 is provided at the connection between the inlet pipes 6a and 3b to prevent leakage of steam from the connection.

With this configuration, the high temperature and high pressure flowing in from the inlet pipe 6a, for example, the pressure is about 35 Kg/cm ² and the temperature is about
Steam at 540°C passes through the inlet pipe 3b and enters the inlet chamber 7, which is the inlet of the blade section 2, flows into the blade section 2, expands adiabatically, and does work, rotating the turbine axle 1 and generating power. The air is then discharged to the exhaust chamber 8, which is the outlet space of the wing portion 2, at a low temperature, for example, about 350° C., and is taken out to the outside. On the other hand, the steam that has entered the inlet chamber 7 flows into the labyrinth 4, but leaks into the labyrinth outlet chamber 9 through the gap in the labyrinth 4. This leaked steam is further prevented from leaking to the outside by the gland packing 5.

However, labyrinth ring 4 as above
When high-temperature steam leaks into the chamber and flows from the inlet chamber 7 to the labyrinth outlet chamber 9, the high-temperature steam comes into contact with the outer casing 6.
There is a problem in that the material of the gland packing 5 must be made of a material that can withstand high temperatures, and the gland packing 5 must also be made of a material that can withstand high temperatures.

[Purpose of the invention] In view of the above-mentioned points, the present invention is designed to prevent steam leaking through the labyrinth provided in the gap between the axle and the inner casing from leaking out from the labyrinth outlet and coming into direct contact with the outer casing. The purpose is to provide a labyrinth structure for a turbine that

[Summary of the idea]

According to the present invention, a hole passing through the inner casing is provided in the middle of the labyrinth part of the steam leakage device provided at the inner casing of the steam turbine and the axle penetration part of the inner casing, and the hole is connected to the hole. By providing a conduit that communicates with the outlet space of the wing, the high-temperature fluid that has flowed into the inlet of the wing leaks through the labyrinth of the axle penetrating portion of the inner casing and flows through the hole and the conduit to the wing. This can be achieved by completely preventing the leakage of high-temperature steam from the labyrinth by guiding it to a low-temperature space at the outlet.

[Example of idea]

Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a sectional view of a turbine equipped with a turbine labyrinth structure according to an embodiment of the present invention. In FIG. 1 and FIGS. 2 and 3, which will be described later, the same parts as in the conventional example shown in FIGS. 4 and 5 are given the same reference numerals. In FIG. 1, the structure and operation of the turbine axle 1, blade section 2, inner casing 3, labyrinth 4, gland packing 5, outer casing 6, etc. are the same as those of the prior art, so their explanation will be omitted. In this embodiment, a hole 3c passing through the inner casing 3 is provided in the middle of a labyrinth 4 provided at a penetrating portion of the inner casing 3, and the hole 3c is connected to the exhaust chamber 8, which is the outlet space of the wing section 2. A conduit 12 is provided. The pipe line 12 is A in Fig. 1.
As shown in FIG. 2, which is a sectional view taken along line A, two through holes 3c are provided in the lower half of the casing 3d of the inner casing 3, and the inner casing 3 is made up of two pipes.

Therefore, high-temperature steam, for example steam at about 540° C., passes through the outer casing 6 and the inner casing 3 and enters the inlet chamber 7 of the wing section 2 via the connected inlet pipes 6a, 3b, and as described above, enters the inlet chamber 7 of the wing section 2. The air flows through the section 2, becomes low temperature, and flows into the exhaust chamber 8 of the outlet space. On the other hand, the high temperature steam in the inlet chamber 7 leaks through the labyrinth 4. However, as illustrated in FIG.
(see figure). In this case, the exhaust chamber 8 and the labyrinth outlet chamber 9 are in communication, so the pressures are the same. Therefore, the pressure in the through hole 3c becomes almost the same as that in the labyrinth outlet chamber 9, and furthermore, the flow path resistance flowing from the through hole 3c to the labyrinth outlet chamber 9 through the downstream labyrinth is between the through hole 3c and the conduit 12.
The high temperature steam does not flow from the through hole 3c to the labyrinth outlet chamber 9 because the resistance is very large compared to the flow path resistance through the through hole 3c.

Therefore, the temperature of the labyrinth outlet chamber 9 is the same as that of the low temperature exhaust chamber 8. Therefore, the material of the outer casing 6 that defines the labyrinth outlet chamber 9 does not need to be a material that can withstand high temperatures, such as high-alloy steel such as Cr-Mo cast steel, but may be a low-alloy steel such as Mo cast steel. .

Note that the gland packing piping disposed in the gland packing 5 also does not need to be made of a material that can withstand high temperatures.

[Effect of idea]

As is clear from the above explanation, according to the present invention, a hole passing through the internal casing is provided in the middle of the labyrinth provided at the penetration part between the turbine axle and the internal casing on the side of the high-temperature fluid inlet chamber. By providing a conduit that connects with the turbine blade and communicates with the low-temperature outlet space of the turbine blade, the high-temperature fluid that has entered the inlet chamber of the turbine blade leaks through the labyrinth, but flows through the hole and pipe into the turbine blade. The hot fluid does not leak into the labyrinth outlet chamber through the labyrinth downstream from the hole. For this reason, the labyrinth outlet chamber is in communication with the outlet space of the turbine blade, and therefore has a low temperature. Therefore, the external casing that defines the labyrinth exit chamber and the gland packing piping installed in the gland packing do not need to be made of materials that can withstand high temperatures as in the prior art, but can be made of materials that can withstand low temperatures, reducing material costs. This has the effect of making it cheaper.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a steam turbine equipped with a turbine labyrinth structure according to an embodiment of the present invention;
The figures are a sectional view taken along line A-A in Fig. 1, Fig. 3 is a partially enlarged sectional view of the labyrinth structure in Fig. 1, Fig. 4 is a sectional view of a steam turbine with a conventional turbine labyrinth structure, and Fig. 5. 4 is a partially enlarged sectional view of the labyrinth structure of FIG. 4. FIG. DESCRIPTION OF SYMBOLS 1... Turbine axle, 2... Blade part, 2a... Moving blade, 2b... Stationary blade, 3... Internal casing, 3b
...Flow path, 3c...hole, 4...labyrinth, 5...
...Grand Patskin as a labyrinth, 6...
External casing, 6a...channel, 8...outlet space, 12...pipe line.

Claims (1)

[Scope of utility model registration request] A turbine axle comprising a turbine axle having a rotor blade, a stationary vane that is combined with the rotor blade of the axle to form a blade part, and an axle penetration part that rotatably penetrates the axle at the closed end, and an open end. It consists of an inner casing that forms a wing outlet at an end, and an outer casing that surrounds the inner casing and has an axle penetration part at both ends that allows the axle to rotatably pass through the axle. In the steam turbine equipped with a leakage device, a hole passing through the inner casing is provided in the middle of a labyrinth portion of the steam leakage device provided in the axle penetrating portion of the inner casing, and an outlet of the blade portion is provided in the hole. A turbine labyrinth structure characterized by connecting pipes that communicate with the space.