JPH10103012A - Gas turbine shroud device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct practical shroud structure capable of effectively utilizing its characteristic even when a ceramic material is used, preventing the flow out of main gas to a cooling side, and using even at high temperature. SOLUTION: A gas turbine shroud device 9 has a cylindrical shroud 11 arranged on the outer circumference side of a moving blade of a main gas flow path inside a gas turbine casing and supported by the casing, and a ceramic fiber bundle 12. The cylindrical shroud 11 is constituted with a plurality of circular arc plate-shaped heat insulating segment 13...13 divided in the circumferential direction C. A ceramic fiber bundle 12 is closely wound in the circumferential direction around a plurality of heat insulating segments 13...13 so as to have the constant thickness (t) in the diameter direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine shroud device, and more particularly to a device for an optimal shroud structure when a ceramic material is used.

[0002]

2. Description of the Related Art In recent years, in the power generation business such as thermal power generation, a power generation system in which a turbine is rotated by high temperature, high pressure and high speed combustion gas to obtain a large output has become mainstream.
In such a power generation system, there is a tendency to increase the efficiency of the gas turbine, in particular, to increase the temperature of the gas turbine inlet, thereby improving the power generation efficiency.

[0003] As measures for raising the temperature of the gas turbine inlet, improvements have been made to metal materials and cooling techniques for various structural members constituting the high-temperature portion of the gas turbine.
In order to satisfy the recent demand for higher temperature, more advanced technology development in both material and cooling is required.

For this reason, in a structural member forming a high-temperature portion such as a gas turbine shroud exposed to a high temperature around the rotor blade,
In general, application of ceramic materials having higher heat resistance than metal materials is expected, and research and development are being vigorously pursued. FIG. 5 shows an example of a conventional gas turbine shroud device expected to be applied to ceramic materials.

FIG. 5 shows components of a cylindrical shroud which is disposed at a position on the outer peripheral side of the mainstream gas passage in the gas turbine casing which faces the rotor blades and which is supported by the casing. 5 illustrates a plurality of arcuate plate-shaped heat insulation segments divided into a plurality of segments.

The heat insulation segment 100 is normally supported by a cylindrical shroud support (not shown) mounted inside the casing. A groove is formed on the inner peripheral surface side of the support along the circumferential direction, and the heat insulating segment 100 is arranged on the opening side in the groove. That is,
The heat-insulating segment 100 is exposed to the high-temperature mainstream gas with its inner peripheral side facing the rotor blades of the mainstream gas passage. By receiving the cooling air supplied into the groove of the support on the outer peripheral side,
The metal part on the outer peripheral side is thermally isolated from the mainstream gas passage.

More specifically, the heat insulation segment 100
As shown in the figure, concave portions 101, 101 are formed at the axial end of the cylindrical shroud in the axial direction AX, and these are fitted and attached to the convex portions formed on the opposing surfaces in the grooves of the shroud support. I have. In addition, the heat insulation segment 10
The thickness of the center portion is smaller than that of the peripheral portion in order to reduce a thermal shock caused by a temperature difference between the outer surface (outer peripheral surface) on the mainstream gas side and the inner surface (inner peripheral surface) on the cooling side. A thin portion 102 is formed. Further, a concave portion 103 and a convex portion 104 forming a pair for a seam are formed at an end of the heat insulating segment 100 in the circumferential direction C, and a fitting structure between the heat insulating segments 100, 100 using the concave and convex portions 103, 104. This prevents the mainstream gas from flowing out from the gap between the segments to the cooling side.

[0008]

However, in the above-mentioned conventional gas turbine shroud device, the fitting structure and the like are premised under the restriction of preventing the mainstream gas from flowing out to the cooling side. Since it is composed of a heat-insulating segment having a complicated shape having many steps and corners, there are the following inconveniences when applying a ceramic material.

That is, in a complex-shaped part having many corners and the like,
Processing is extremely difficult due to restrictions during sintering of the ceramic material, and a complicated mold is required in the ceramic forming step, so that it is not always practical. Even if the above complex shaped parts are made of ceramics, ceramics are generally brittle, unlike metals, so there is also a problem that cracks are generated from steps and corners when subjected to impact, and they are easily broken. there were.

Therefore, in the conventional gas turbine shroud device, even if the heat insulating segment is simply replaced with a ceramic material from a metal material, it is not always possible to effectively exert the excellent heat resistance expected of ceramics.

The present invention has been made in consideration of such a conventional problem, and even when a ceramic material is used, its characteristics can be effectively utilized, and the mainstream gas flows to the cooling side. It is an object of the present invention to construct a practical shroud structure capable of withstanding use under a high temperature in order to prevent such a problem.

[0012]

In order to achieve the above object, the present inventor has found that the characteristics required of a gas turbine shroud when a ceramic material is used, that is, 1) sufficient heat resistance to a high-temperature mainstream gas. Exhibiting the metal that forms the structure around the blade by controlling the temperature rise 2): Avoid brittle and catastrophic failure even when the blade vibrates and comes into contact with the shroud. I have been studying and researching.

For example, in a conventional measure for suppressing the temperature of a metal from being raised,
Although the mainstream gas inflow from the gap between the heat insulation segments was suppressed by the fitting structure, requesting a similar structure for the ceramics was not advisable because of the problems of the processed surface and the brittle surface described above. Do you get it.

Further, as a measure for enhancing the toughness of ceramics,
In recent years, it has been conceived to use ceramic-based fiber composite materials, which have been in the limelight. However, in this case as well, it takes time and cost to accurately process complex-shaped components such as fitting structures, as described above. Not a target. Moreover, in the heat-insulating segments made from composite materials by various processes,
In addition to easily causing excessive damage to the fiber, even if the fiber is sound, when the high-temperature mainstream gas flows into the fitting part, thermal stress depending on the shape of the fitting part is likely to occur, and the toughness is enhanced. It turns out that the benefits cannot always be fully exploited.

Therefore, the present inventor has focused on a new shroud structure that fills the gap between the heat insulation segments with a relatively simple shape, instead of a fitting structure using a step, and as a result,
The inventor has found that the inflow of mainstream gas can be effectively suppressed by densely winding long fibers around the cooling side of the heat-insulating segment, and has completed the invention described below.

That is, according to the present invention, there is provided a cylindrical shroud which is disposed on the outer peripheral side of a moving blade of a mainstream gas passage in a gas turbine casing and is supported by the gas turbine casing. The gas turbine shroud device comprises a plurality of arc-shaped plate-shaped heat-insulating segments divided along, and separates an outer peripheral metal portion from the mainstream gas passage by the plurality of heat-insulating segments. It is characterized in that a ceramic fiber bundle is densely wound along the circumferential direction with a certain thickness in the radial direction on the outer peripheral side of the segment.

By arranging the ceramic fiber bundle in this manner, the mainstream gas flowing from the circumferential gap between adjacent heat-insulating segments can be more effectively suppressed by the fiber bundle. Therefore, there is no restriction on the fitting structure conventionally required for the heat-insulating segments, and a simple-shaped heat-insulating segment that does not require a step portion or the like assuming a non-fitting state can be constructed. However, it is possible to provide a practical gas turbine shroud that can be easily processed, fully exerts its advantages, and can withstand use at high temperatures.

In a preferred aspect of the present invention, the plurality of heat insulating segments are arranged side by side in a non-fitting state along the circumferential direction. The plurality of heat insulating segments are preferably made of a ceramic material, and the ceramic material is preferably a ceramic-based fiber composite material. In this case, since the toughness can be enhanced by compounding the fibers, there is an advantage that damage when a foreign object is received is hardly minimized, for example.

The ceramic fiber bundle is preferably composed of a SiC-based fiber bundle. The ceramic fiber bundle is preferably a woven structure woven by a manufacturing method such as braiding. In this case, there is an advantage that the number of times of winding the heat insulating segment around the outer periphery can be reduced.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a gas turbine shroud device according to the present invention will be described below with reference to FIGS. This embodiment is applied to a gas turbine shroud device arranged on the outer peripheral side of a first stage rotor blade in a mainstream gas passage.

FIG. 1 shows a peripheral portion of a mainstream gas passage F1 along a first stage stationary blade 2, a first stage moving blade 3, and a second stage stationary blade 4 in a gas turbine casing 1. As shown in FIG. A plurality of cylindrical structural members are arranged on the outer peripheral side of the mainstream gas passage F1.

The plurality of structural members are supported by a casing 1, specifically, a first stage and a second stage stationary blade 2,
4, a support wall 5 and 6, a seal wall 7 which is arranged on the outer peripheral side of the support 5 and is attached to the casing 1, a shroud support 8 which is arranged on a side facing the rotor blade 2, and a support The gas turbine shroud device 9 according to the present invention is disposed on the inner peripheral side of the gas turbine shroud 8. In these structural members, a cooling passage 10 part of which is connected to the mainstream gas passage is formed along the axial direction and the circumferential direction, and cooling air is caused to flow along the cooling passage 10. In addition, a rise in temperature due to a high-temperature mainstream gas from the inner wall of the passage is suppressed.

On the inner wall side of the shroud support 8, a groove 8a connected to the cooling passage 10 is formed in the circumferential direction, and the main flow gas passage F1 in the groove 8a has a surface facing the axial direction AX.
A pair of recesses 8b, 8b are formed. The shroud support 8 is configured such that the axial end of the gas turbine shroud device 9 is fitted and supported in the recesses 8b, 8b, so that the metal part on the outer peripheral side of the shroud device 9 which receives the cooling air flows. It is thermally isolated from the gas passage F1.

The gas turbine shroud device 9 includes a cylindrical shroud 11 disposed on the outer peripheral side of the rotor blade 3 of the mainstream gas passage F1 and supported by the shroud support 8, and a ceramic disposed on the outer peripheral side of the shroud 11. And a fiber bundle 12.

As shown in FIG. 2, the cylindrical shroud 11 is divided along the circumferential direction C and arranged in a groove 8a of the support 8 at regular intervals. .. 13).

Each of the heat-insulating segments 13 is made of, for example, a SiC ceramic material, and is arranged on the opening side in the groove 8a of the support body 8 and has an arc shape in the circumferential direction C as shown in FIGS. An extending base 13a and this base 13
a of the support 8 protruding from both ends in the axial direction AX to the bottom side in the groove 8a and located outside the axial direction AX.
A part having a channel structure having two side walls 13b, 13b extending in a brim shape so as to be fitted to the b, 8b sides, and a channel (recess) CH formed on the outer peripheral side by the base 13a and both side walls 13b, 13b. It is configured.

The ceramic fiber bundle 12 is made of, for example, SiC
The bundle is made of a woven structure obtained by weaving a bundle of long fibers by braiding or the like. As shown in FIGS. By tightly winding in the circumferential direction C with the thickness t, a gap in the circumferential direction C between the adjacent heat insulating segments 13 is filled.

Therefore, in this embodiment, by wrapping the fiber bundle around the outer circumference of the heat insulating segment, the main gas flowing from the gap between the adjacent heat insulating segments to the cooling side can be suppressed by the fiber bundle, and the main flow gas flowing to the cooling side can be suppressed. It is possible to more effectively avoid raising the temperature of the metal structural member around the rotor blade due to the gas.

In addition, instead of the conventional fitting structure, a heat-insulating segment having a simple shape that can be arranged at regular intervals can be newly constructed. As a result, a practical gas turbine shroud device using a ceramic material can be manufactured at a relatively low cost. Can be provided.

In this embodiment, the heat-insulating segments are formed in a channel structure. However, the present invention is not limited to this. The fiber bundle can be densely wound around at least the outer peripheral side of the cylindrical shroud. Any structure is acceptable.

Further, in this embodiment, the present invention is applied to the gas turbine shroud device of the first stage rotor blade, but is not limited to this, and the gas arranged on the outer peripheral side of the rotor blade of the second stage and subsequent stages in the mainstream gas passage is used. Even when applied to a turbine shroud device, the same effect as described above can be exerted.

[0032]

As described above, according to the present invention, the ceramic fiber bundle is densely wound around the outer periphery of the plurality of heat insulating segments with a constant thickness in the radial direction along the circumferential direction. The mainstream gas flowing out to the cooling side from the gap between the segments can be effectively suppressed by the fiber bundle, and the temperature rise of the metal part around the rotor blade caused by the mainstream gas can be effectively avoided.

In addition, instead of the conventional fitting structure, it is possible to newly construct a heat-insulating segment having a simple shape that can be arranged at a fixed interval, and as a result, a practical gas turbine shroud device using a ceramic material can be manufactured at a relatively low cost. Can be provided. This effect is maximized particularly when the heat insulation segment is formed of a ceramic material, preferably a ceramic base fiber material, when the ceramic fibers are formed of SiC-based fibers, or when the fiber bundle is formed of a woven structure. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a peripheral portion of a mainstream gas passage in which a gas turbine shroud device according to the present invention is disposed.

FIG. 2 is a schematic perspective view showing a main structure of the gas turbine shroud device.

FIG. 3 is a schematic plan view of the gas turbine shroud device as viewed from an outer peripheral side.

FIG. 4 is a schematic view of the gas turbine shroud device taken along line AA in FIG. 3;

FIG. 5 is a schematic perspective view illustrating a conventional heat insulating segment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas turbine casing 2 First stage stationary blade 3 First stage moving blade 4 Second stage stationary blade 5, 6 Support 7 Seal wall 8 Shroud support 8a Groove 8b Depression 9 Gas turbine shroud device 10 Cooling passage 11 Cylindrical shroud 12 Ceramic fiber bundle 13 Heat insulation segment 13a Base 13b Side wall CH channel

Claims (6)

[Claims] 1. A gas turbine according to claim 1, further comprising: a cylindrical shroud disposed on an outer peripheral side of a moving blade of a mainstream gas passage in the gas turbine casing and supported by the gas turbine casing. The cylindrical shroud is divided along a circumferential direction thereof. A gas turbine shroud device comprising a plurality of arc-shaped plate-shaped heat-insulating segments, and separating the metal part on the outer peripheral side from the mainstream gas passage by the plurality of heat-insulating segments. Characterized in that a ceramic fiber bundle is densely wound along a circumferential direction with a constant thickness in a radial direction. 2. The gas turbine shroud device according to claim 1, wherein the plurality of heat insulation segments are arranged side by side in a non-fitting state along the circumferential direction. 3. The gas turbine shroud device according to claim 1, wherein said plurality of heat insulating segments are made of a ceramic material. 4. The gas turbine shroud according to claim 3, wherein the ceramic material is a ceramic-based fiber composite material. 5. The gas turbine shroud according to claim 1, wherein the ceramic fiber bundle is a SiC-based fiber bundle. 6. The gas turbine shroud according to claim 1, wherein the ceramic fiber bundle is formed of a woven structure.