JPH0749002A - Steam turbine high pressure casing - Google Patents

Abstract

PURPOSE:To prevent the thermal deformation of an outer casing by eliminating the contraflow of high temperature steam on the upper wheel side even with the generation of circumferential pressure unbalance at a medium pressure inlet part. CONSTITUTION:A thermal shield member 12 in a steam turbine high pressure casing is formed into double pipe structure constituted of an inner cylinder 12a and an outer cylinder 12b, and the inner surface of the inner cylinder 12a on the medium pressure inner casing 16 side is brought into contact with a medium pressure inner casing 16 through a metal O-ring 22 so as to shut off a slit 13 provided between an outer casing 4 and the thermal shield member 12. A slit 21 is provided at the whole periphery of the medium pressure inner casing side end face of the double pipe forming the thermal shield member 12, and a space 23 is provided between the inner and outer cylinders 12a, 12b. A hole 24 is further provided at the upper part of the inner cylinder 12a, and a shield internal space 11 is communicated with a medium pressure inlet part 10 through the slit 21, space 23 and hole 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine high pressure vehicle compartment, and more particularly to improvement of a thermal shield portion thereof.

[0002]

2. Description of the Related Art FIG. 3 shows the entire structure of a conventional steam turbine high-pressure casing, and FIG. 4 shows a detailed structure of a thermal shield part by enlarging a part of FIG.

In these drawings, the driving steam flows from the high pressure inlet pipe 1 into the speed control stage 2 and is guided to the high pressure section blade row 3. The steam that has flowed out from the high pressure section blade row 3 is then guided to the outside of the outer casing 4 and reheated,
The medium pressure inlet pipe 5 flows into the medium pressure part blade row 6.

A part of the steam flowing out from the high-pressure section blade row 3 passes through the gap 8 between the high-pressure inner casing 7 and the outer casing 4, and is discharged from the nozzle 9 provided in the high-pressure inner casing 7 to the inside. Inlet part 1
It flows into the shield inner space 11 adjacent to 0. This inflowing steam then merges into the intermediate pressure inlet portion 10 through the slit 13 provided between the outer casing 4 and the thermal shield member 12, as shown in detail in FIG. After passing through the pressure section blade row 6, the medium pressure exhaust chamber 14 flows out of the vehicle interior.

In this way, the thermal shield internal space 1
The temperature rise in the outer casing 4 is prevented by introducing the outflow steam from the high-pressure section blade row 3 having a temperature lower than that of the reheated steam into the outer casing 1.

[0006]

By the way, in the above-mentioned configuration, in the conventional case, the outer casing 4 is so arranged that the residual pressure of the cooling steam is likely to drop when the intermediate pressure inlet portion 10 becomes a low pressure when the load is cut off. The outflow area of the slit 13 provided between the heat shield member 12 and the thermal shield member 12 is set to be several tens of times larger than the outflow area of the nozzle 9. Therefore, the pressure difference between the shield internal space 11 and the intermediate pressure inlet 10 is several tens of mmAq.
Becomes extremely small. Further, since the intermediate pressure inlet pipe 5 is located on the lower vehicle side, the pressure at the intermediate pressure inlet portion 10 on the upper vehicle side is slightly higher than that on the lower vehicle side due to the influence of the dynamic pressure of the inflow steam.

Therefore, as shown in FIG. 5, a reverse flow 15 from the intermediate pressure inlet 10 to the shield inner space 11 is generated on the turbine upper side, and steam moves in the circumferential direction and flows out from the lower side. It becomes a pattern. Therefore, on the vehicle side, the temperature of the outer casing 4 becomes high due to the backflow 15 of the high-temperature reheated steam, causing a temperature imbalance in the circumferential direction, and the outer casing 4 is thermally deformed to cause a problem such as steam leakage. .

The present invention has been made in order to solve the above-mentioned problems of the prior art. Even if a temperature imbalance in the circumferential direction occurs at the intermediate pressure inlet, the backflow of high-temperature steam on the vehicle side is generated. It is an object of the present invention to provide a thermal shield for a steam turbine high-pressure vehicle compartment that effectively prevents thermal deformation of the outer vehicle compartment.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a part of the steam flowing out from a high pressure section blade row of a steam turbine is passed through a gap between a high pressure inner casing and an outer casing. From the nozzle provided in the high-pressure inner casing to flow into the shield internal space adjacent to the medium-pressure inlet portion, and the inflowing vapor is introduced from the slit provided between the outer casing and the thermal shield member to the medium-pressure inlet. In the steam turbine high-pressure vehicle compartment, which is made to join the engine part and passes through the middle-pressure section blade row together with the reheated steam to flow out from the medium-pressure exhaust chamber to the outside of the vehicle compartment, the thermal shield member is separated from the inner cylinder and the outer cylinder. A double tube structure having a double-pipe structure including: the inner cylinder inner surface on the medium-pressure inner casing side, which is in contact with the medium-pressure inner casing via an O-ring to block the slit, and which constitutes a thermal shield member. Slits are installed on the entire circumference of the end surface of the medium-pressure interior compartment. Rutotomoni, a space is provided between the inner and outer tubes, with a hole in the top of the inner cylinder is further provided, in which communicating the shield interior space in the middle pressure inlet portion.

[0010]

According to the above means, the thermal shield member in the steam turbine high-pressure casing is a double pipe consisting of the inner and outer cylinders, and the inner surface of the inner cylinder on the medium-pressure inner car side is connected to the medium-pressure inner cylinder through the metal O-ring. The slit provided between the outer casing and the thermal shield member is brought into contact with the passenger compartment, and a slit is provided on the entire circumference of the end face of the double pipe forming the thermal shield member on the side of the medium pressure inner casing. A space is provided between the inner and outer cylinders, and a hole is further provided in the upper part of the inner cylinder so that the shield inner space communicates with the medium pressure inlet portion, so that the cooling steam flowing into the shield inner space constitutes a thermal shield member. There is a pressure imbalance at the middle pressure inlet because the slits around the end surface of the double pipe in the middle pressure inner wheel side and the space between the inner and outer cylinders go through the hole in the upper part of the inner cylinder to the middle pressure inlet. However, the backflow of high-temperature steam can be prevented.

[0011]

Embodiments of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a sectional view showing a configuration of a main part of a steam turbine high-pressure vehicle cabin according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. Since the entire configuration is the same as that of the conventional one, refer also to FIG. 3 as it is, and the same reference numerals are used for the same components.

Also in the present invention, as shown in FIGS. 1 to 3, driving steam flows from the high pressure inlet pipe 1 into the speed control stage 2 and is guided to the high pressure section blade row 3. The steam that has flowed out from the high pressure section blade row 3 is then guided to the outside of the outer casing 4 and reheated,
The medium pressure inlet pipe 5 flows into the medium pressure part blade row 6. Further, a part of the steam flowing out from the high-pressure section blade row 3 is part of the high-pressure inner casing 7
It passes through the gap 8 between the outer casing 4 and the outer casing 4, and flows from the nozzle 9 provided in the high-pressure inner casing 7 into the shield inner space 11 adjacent to the medium pressure inlet portion 10. According to the present invention, this inflow steam Does not merge into the intermediate pressure inlet portion 10 through the slit 13 provided between the outer casing 4 and the thermal shield member 12, but through the slit 21 provided in the double-tube thermal shield member 12. Join the medium pressure inlet section 10,
Then, after passing through the middle pressure blade row 6 together with the reheated steam, it flows out from the middle pressure exhaust chamber 14 to the outside of the vehicle compartment.

That is, according to the present invention, as shown in FIG. 1 and FIG. 2, the thermal shield member 12 has a double pipe structure composed of an inner cylinder 12a and an outer cylinder 12b. Then, the inner surface of the inner cylinder 12a on the side of the medium-pressure inner casing 16 is covered with a metal O-ring 22.
The inner space 16 of the intermediate pressure through the slit 13
Is shut off. In addition, a slit 2 is formed on the entire circumference of the end surface of the double pipe forming the thermal shield member 12 on the side of the medium-pressure interior compartment.
1 is provided, an appropriate space 23 is provided between the inner and outer cylinders 12a and 12b, and a hole 24 is further provided at the upper portion of the inner cylinder 12a so that the shield inner space 11 communicates with the intermediate pressure inlet 10. .

With such a structure, the cooling steam that has flowed into the shield inner space 11 has slits 21 on the entire circumference of the end face on the side of the medium-pressure inner casing 16 of the double pipe forming the thermal shield member, the inside and the outside. Even if there is a pressure imbalance in the intermediate pressure inlet portion 10 by flowing out from the hole 24 in the upper portion of the inner cylinder 2a to the intermediate pressure inlet portion 10 through the space 23 between the cylinders 2a and 2b, the reverse flow of the high temperature steam is prevented. It can be prevented.

[0015]

As described above, according to the present invention, the thermal shield member in the steam turbine high-pressure casing is a double pipe consisting of the inner and outer cylinders, and the inner surface of the inner cylinder on the medium pressure inner car side is made of metal O. The inner surface of the double-pipe inner-pressure compartment, which is in contact with the inner-compartment inner-pressure compartment via a ring, blocks the slit provided between the outer compartment and the thermal shield member, and constitutes the thermal shield member. By providing a slit on the entire circumference, a space between the inner and outer cylinders, and a hole on the upper part of the inner cylinder, and communicating the shield inner space with the intermediate pressure inlet part, the cooling steam flowing into the shield inner space is Since the double pipe that constitutes the thermal shield member has a slit on the entire circumference of the end face on the side of the medium pressure inner car and the space between the inner and outer cylinders, it flows out from the hole in the upper part of the inner cylinder to the medium pressure inlet, Prevents backflow of high temperature steam even if there is pressure imbalance Kill.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a main part of a steam turbine high-pressure casing according to an embodiment of the present invention.

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

FIG. 3 is a cross-sectional view showing the overall configuration of a conventional steam turbine high-pressure casing.

FIG. 4 is an enlarged view of a part of FIG. 3 showing in detail the structure of a thermal shield part.

5 is a view showing a circumferential flow state of the thermal shield portion along the line VV in FIG.

[Explanation of symbols]

 1 High-pressure inlet pipe 2 Speed control stage 3 High-pressure part blade row 4 Outer casing 5 Medium-pressure inlet pipe 6 Medium-pressure portion blade-row 7 High-pressure inner casing 8 Gap 9 Nozzle 10 Medium-pressure inlet 11 Shield inner space 12 Thermal shield member 12a Inner cylinder 12b Outer cylinder 13 Slit 14 Medium pressure exhaust chamber 16 Medium pressure inner casing 21 Slit 22 O-ring 23 Space 24 hole

[Procedure amendment]

[Submission date] May 30, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

The present invention has been made in order to solve the problems of the prior art as described above.
An object of the present invention is to provide a thermal shield for a high-pressure steam turbine cabin that prevents backflow of high-temperature steam on the vehicle side even when a pressure imbalance occurs, and effectively prevents thermal deformation of the outer casing.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

With such a structure, the cooling steam that has flowed into the shield inner space 11 has slits 21 on the entire circumference of the end face on the side of the medium-pressure inner casing 16 of the double pipe forming the thermal shield member, the inside and the outside. Space 2 between the cylinders 12a and 12b
3 through the hole 24 in the upper part of the inner cylinder 12a to the intermediate pressure inlet 1
By flowing to 0, even if there is a pressure imbalance in the intermediate pressure inlet portion 10, it is possible to prevent the high temperature steam from flowing back.

Claims (1)

[Claims] 1. A part of steam flowing out from a blade row of a high-pressure part of a steam turbine is passed through a gap between a high-pressure inner casing and an outer casing from a nozzle provided in the high-pressure inner casing to a medium-pressure inlet portion. To the inner space of the shield adjacent to the, the inflowing steam is merged into the intermediate pressure inlet part from the slit provided between the outer casing and the thermal shield member, and the intermediate pressure blade row is passed together with the reheated steam. In a high-pressure steam turbine cabin that is designed to flow from the medium-pressure exhaust chamber to the outside of the vehicle compartment, the thermal shield member has a double-pipe structure consisting of an inner cylinder and an outer cylinder, and the inner cylinder inner surface on the medium-pressure inner compartment side. Is abutted on the medium-pressure inner casing via an O-ring to block the slit, and a slit is provided on the entire circumference of the end face on the medium-pressure inner casing side of the double pipe constituting the thermal shield member, A space is provided between the inner and outer cylinders, and there is a hole in the top of the inner cylinder. Provided, steam turbine high pressure casing, characterized in that communicating the shield interior space in the middle pressure inlet portion.