JPH08254106A - Supporting structure for shroud casing for turbine - Google Patents

Abstract

PURPOSE: To provide a supporting structure of a shroud casing for turbines, which is capable of permitting radial expansion of the shroud casing exposed to high temperatures, and of preventing the shroud easing from being off-centered. CONSTITUTION: In a supporting structure of a shroud casing of turbines in which a ring-shaped shroud casing 1 is arranged a specified gap apart from the tips of plural turbine blades 12 circumferentially installed on a turbine disk 10, and the shroud casing 14 is supported by supporting members 29x, 29y, at least three or more radial pins 28 are provided to the supporting members 29x, 29y so that they are on radial lines passed through the center of the shroud casing 14 at about equal intervals in the circumferential direction of the shroud casing 14. Thus, the shroud casing 14 is supported on the supporting members 29x, 29y through the radial pins 28 so that it can freely expand and contract in relation to heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a shroud casing for a turbine used in a gas turbine or a jet engine.

[0002]

2. Description of the Related Art An outline of a gas turbine is shown in FIG. As shown in the figure, the air sucked through the intake duct 1 is compressed in two stages by the first and second stage compressors 2 and 3 and then introduced into the combustion chamber 4 to be mixed with fuel. It is ignited by the ignition device 5. The combustion gas is in the duct 6
After driving the first-stage and second-stage turbines 7, 8 through the exhaust pipe, the exhaust gas is discharged. The rotations of the first-stage and second-stage turbines 7 and 8 are transmitted to the first-stage and second-stage compressors 2 and 3 via the carbic joints 7a and 8a provided at the front portions of the turbine disks.

Details of the first and second stage turbines 7, 8 are shown in FIG. Tension bolt 9 as shown
In addition, the turbine disk 10 for the first stage and the second stage
a and 11a are fixed, and a plurality of turbine blades 12a and 13a are provided on these turbine disks 10a and 11a at intervals in the circumferential direction. Ring-shaped shroud casings 14a and 15a are arranged outside the turbine blades 12a and 13a with a predetermined gap from the tips of the blades.

The shroud casings 14a and 15a are
The bolt 17a is attached to the support member 16a provided outside thereof.
It is supported and fixed by. A plurality of bolts 17a are provided at predetermined intervals in the circumferential direction. A turbine blade 18a for stationary blades is provided on the upstream side of each of the turbine blades 12a and 13a for moving blades.

[0005]

By the way, since the shroud casing 14a is exposed to combustion gas at a high temperature (800 ° C. or higher), it is expanded in diameter by thermal expansion. Therefore, the bolt 17 supporting the shroud casing 14a
There is a risk that a acts to suppress the diameter expansion of the shroud casing 14a and is damaged.

Further, the shroud casing 14a whose diameter expansion is suppressed may be deformed and eccentric, and the casing 14a and the blade 12a may come into contact with each other to damage the turbine blade 12a. Further, due to such a problem, restarting after operation may not be possible. Further, the bolt 17a may be seized and may not be disassembled.

An object of the present invention, which was devised in view of the above circumstances, is to allow the radial expansion of the shroud casing exposed to high temperature and to prevent the eccentricity of the shroud casing from supporting the structure of the shroud casing. To provide.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a ring-shaped shroud casing with a predetermined gap from the tips of a plurality of turbine blades provided around a turbine disk. In a support structure for a shroud casing for a turbine, the support member provided on the outer side of the shroud has at least three radial pins provided on the support member at substantially equal intervals in the circumferential direction of the shroud casing. The shroud casing is provided on a radial line passing through the center of the casing, and the shroud casing is supported by a support member so as to be expandable and contractible with respect to heat via these radial pins.

[0009]

According to the above construction, even if the shroud ring is expanded in diameter due to the difference in thermal expansion between when the shroud is cold and when it is hot, the radial pins are oriented in the radial direction, and the expansion deformation can be escaped. Further, since at least three radial pins are provided on the radial line passing through the center of the shroud casing at substantially equal intervals in the circumferential direction of the shroud casing, the core of the shroud ring that expands in diameter is also held.

[0010]

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an enlarged view of the first and second stage turbines 7, 8 of the gas turbine shown in FIG. As shown in the drawing, the first-stage and second-stage turbine disks 10 and 11 are inserted into the tension bolt 9, and are tightened and fixed by a nut 19 screwed to the end of the tension bolt 9. ing. That is, the turbine disks 10 and 11 are connected to the second
It is connected to the impeller 21 of the compressor of the stage and is fixed by being tightened by the nut 19.

A plurality of turbine blades 12, 1 are provided on the turbine disks 10, 11 at predetermined intervals in the circumferential direction.
3 are installed around. Ring-shaped shroud casings 14 and 15 are arranged outside the turbine blades 12 and 13 with a predetermined gap from the tips of the blades.

As shown in FIG. 2, the shroud casing 14 is composed of an integrally molded ring body. On the outer circumference of the shroud casing 14, a convex portion 24 is formed along the circumferential direction at a substantially central portion in the axial direction.
As shown in FIG. 4, on the convex portion 24, five casing-side pin holes 25 are formed on a radial line 27 passing through the center 26 of the shroud casing 14 at intervals of 72 degrees in the circumferential direction. A radial pin 28 is slidably fitted in these pin holes 25.

As shown in FIG. 2, the convex portion 24 has a supporting member 29 provided outside the shroud casing 14.
It is sandwiched from the front and back and supported so that it can expand and contract in the radial direction. The support member 29 includes a front ring body 29x integrally formed with the fixed frame 30 and a rear ring body 29y fastened to the front ring body 29x with bolts 31. As shown in FIG. 3, a plurality of bolts 31 are provided at equal intervals in the circumferential direction.

Front ring body 29 which constitutes the support member 29
On the inner peripheral surface of x, as shown in FIG. 4, the support member side pin hole 32 into which the radial pin 28 is slidably inserted.
Is perforated. Similar to the casing-side pin holes 25, five pin holes 32 are formed on the radial line 27 passing through the center 26 of the shroud casing 14 at 72 ° intervals in the circumferential direction. As a result, the rotation of the shroud casing 14 is restricted via the radial pin 28, and the shroud casing 14 is coaxially supported by the support member 29 via the radial pin 28.

As shown in FIG. 4, between the outer peripheral surface of the convex portion 24 and the inner peripheral surface of the front ring body 29x, thermal expansion (thermal expansion) of the shroud casing 14 in the radial direction is performed. A clearance 33 is provided to allow it. Similarly, FIG.
As shown in FIG. 4, a gap 34 is formed between the outer peripheral surface of the shroud casing 14 and the inner peripheral surfaces of the front and rear ring bodies 29x, 29y for allowing thermal expansion of the shroud casing 14 outward in the radial direction. Is provided.

Further, as shown in FIG. 2, a ring-shaped cover plate 35 is attached to the outer periphery of the front ring body 29x with bolts 36. The lid plate 35 functions as a lid that prevents the radial pin 28 from falling off. As shown in FIG. 3, the plurality of bolts 36 are provided at equal intervals in the circumferential direction.

The operation of this embodiment having the above configuration will be described.

When the gas turbine is operated, the shroud casing 14 is exposed to high-temperature (800 ° C. or higher) combustion gas, so that the shroud casing 14 expands in diameter due to thermal expansion. Here, since the radial pin 28 that supports the shroud casing 14 on the support member 29 is oriented in the radial direction, the shroud casing 14 expands and contracts in the range of the gaps 33 and 34, and its expansion deformation is released.

Further, five radial pins 28 are arranged at substantially equal intervals in the circumferential direction of the shroud casing 14,
Radial line 27 passing through the center 26 of the shroud casing 14.
Since it is provided above, the core of the shroud casing 14 that expands in diameter is also held. That is, the shroud casing 14 is guided by the five radial pins 28 and expands / contracts along the radial pins 28, so that the center deviation of the shroud casing 14 due to the expansion / contraction is prevented.

That is, the radial pin 28 allows the shroud casing 14 to expand and contract due to thermal expansion, and at the same time, has a function of preventing the center deviation due to the thermal expansion and contraction of the shroud casing 14. In order to exert such a function, the number of radial pins 28 is not limited to five, and may be three or more at substantially equal intervals in the circumferential direction. However, the larger the number, the higher the supporting rigidity.

Further, since the shroud casing 14a is not fastened with the bolts 17a unlike the conventional one shown in FIG. 6, there is no possibility that the bolts 17a will be seized and cannot be disassembled. Further, the support member 29 is composed of a front ring body 29x and a rear ring body 29y, and the protrusion 24 formed in a brim shape along the circumferential direction of the shroud casing 14 is fitted into the ring-shaped groove between them. Therefore, gas leakage from the high pressure side (upstream side of the turbine blade 12) to the low pressure side (downstream side of the turbine blade 12) is prevented.

The supporting structure of the shroud casing 14 according to this embodiment is applied only to the first stage turbine 7 side as shown in FIG. 1, and the shroud casing 15 on the second stage turbine 8 side is the same as the conventional one. The bolts 17 are used because the first-stage turbine 7 side has a thermally severer condition. However, it goes without saying that it may be applied to the second stage turbine 8 side. Also, in FIG.
18 is a turbine blade for a stationary blade.

[0024]

In summary, according to the turbine shroud casing support structure of the present invention, it is possible to allow radial expansion of the shroud casing exposed to high temperatures and prevent eccentricity of the shroud casing.
Therefore, the deformation and eccentricity of the shroud casing due to thermal stress can be prevented, and the eccentric contact with the turbine blade can be prevented in advance.

[Brief description of drawings]

FIG. 1 is a side sectional view of a main part of a support structure for a shroud casing for a turbine showing an embodiment of the present invention.

FIG. 2 is a side sectional view of the support structure, which is taken along line II-O- of FIG.
It is a II sectional view.

FIG. 3 is a view taken along the line III-III of FIG.

FIG. 4 is a view taken along the line IV-IV of FIG.

FIG. 5 is a schematic diagram of a gas turbine.

FIG. 6 is a side sectional view of a main part of a supporting structure for a shroud casing for a turbine showing a conventional example.

[Explanation of symbols]

 10 Turbine Disk 12 Turbine Blade 14 Shroud Casing 26 Center 27 Radius 28 Radial Pin 29 Support Member

Claims (1)

[Claims] 1. A ring-shaped shroud casing is arranged with a predetermined gap from the tips of a plurality of turbine blades provided around a turbine disk, and the shroud casing is supported by a support member provided outside thereof. In the support structure for a shroud casing for a turbine, at least three or more radial pins are provided on the support member on a radial line passing through the center of the shroud casing at substantially equal intervals in the circumferential direction of the shroud casing, and these radial pins are provided. A support structure for a shroud casing for a turbine, wherein the shroud casing is supported by a support member so as to be expandable and contractible with respect to heat.