JPH10252490A - Ceramic gas turbine structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool an outer peripheral part of a back plate and reduce stress by forming a space surrounded by at least a part of the back plate and a housing on an outer peripheral side of a cylindrical part of the back plate and forming a hole into which air is introduced in the housing which constitutes this space. SOLUTION: A shroud 12 and a scroll 4 which are arranged on outer periphery of a rotor of a turbine 5 are accumulated on a ceramic back plate 3, and a cylindrical part 2 of the back plate 3 is elastically pressed against a bearing housing 1. A small hole for introducing cooling air to an outer peripheral side of the back plate 3 is provided in a ring plate 10, and a slit is formed in a contact part of the back plate 3 and a thermal insulation material 11. Consequently, when a clearance occurs in a fitting part A, cooling air from an outlet of a compressor flows along a surface on a housing side of the back plate 3 to reduce temperature gradient on inner and outer peripheries of the back plate 3 and reduce stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a structure of a ceramic gas turbine.

[0002]

2. Description of the Related Art As a structure of a conventional ceramic gas turbine, for example, there is a structure as shown in FIG. 10 as disclosed in Japanese Utility Model Publication No. 63-3361.
To explain the configuration of the prior art, reference numeral 5 denotes a turbine rotor, and a shaft 19 of the turbine rotor 5 is attached to the bearing housing 1 via a bearing 16. Hole 2
Numeral 0 denotes a path of the lubricating oil supplied to the bearing 16.
It communicates with a space with space. The hole 6 is a path for low-temperature and high-pressure air such as air at the outlet of the compressor.
It communicates between 1 and 7-2 to supply seal air.
In order to prevent a part of the lubricating oil from leaking into the turbine rotor side, the seal air has a smaller seal air pressure than the seal oil pressure supplied between the seal rings 7-1 and 7-2 than the lubricating oil pressure supplied to the space of the bearing 16. Is set to be higher. On the other hand, the seal air leaks into the lubricating oil side and the turbine rotor side.

[0003] Reference numeral 21 denotes a turbine shroud integrated with a diffuser. The resilient support structure 8 attached to the engine housing 9 fixed to the bearing housing allows the nozzle 17 and the nozzle 17 to move with respect to the bearing housing 9.
A part of the scroll 4, a shim 22 made of a fibrous heat insulating paper, a part of the back plate 3, and a member formed by being pressed through the formed heat insulating material 11. Also,
The turbine rotor 5, the nozzle 17, the scroll 4, the turbine shroud 21, and the back plate 3 are made of ceramic such as silicon carbide or silicon nitride.

[0004] The turbine shroud 21 needs to maintain its axis with respect to the turbine rotor 5 with high accuracy. For this reason, the turbine is attached to the bearing housing via the bearing 16, so that the axis of the turbine is accurately maintained with respect to the bearing housing. Further, the axial center of each of the ceramic components of the nozzle 17, the scroll 4, the turbine shroud 21, and the back plate 3 is maintained by fitting in the respective radial directions. Further, the shaft cores of the bearing housing 1 and the back plate 3 are structured to be held by the fitting portion A. Therefore, the turbine shroud 21
Can accurately maintain the axis with respect to the turbine rotor 5. At normal temperature during assembly, the back plate and the bearing housing form an axis by fitting A as described above. However, the conical tapered portion of the heat insulating material integrally attached to the back plate 3 and the bearing housing cone are formed. The configuration is also such that the shaft center is also provided at the same time in the tapered portion having the shape. Therefore, even when the bearing housing and the back plate having different thermal expansions become hot when operating under a high load, and a gap is generated in the fitting portion A, the conical taper portion of the heat insulating material and the conical taper of the bearing housing may be formed. The tapered portion is configured such that the axial center can be maintained only by a slight shift in the axial direction (a degree that does not affect a change in efficiency due to a change in chip clearance).

[0005]

However, in such a conventional ceramic gas turbine structure, the nozzle and the scroll become high in temperature near the gas temperature during operation at a high load of 1300 ° C. or higher at the turbine inlet temperature. The outer peripheral side of the back plate 3 that comes into contact therewith has a high temperature of, for example, about 1000 to 1200 ° C., though the heat insulating material is interposed. On the other hand, the inner peripheral side of the back plate 3 has a low temperature of about 100 ° C. which leaks to the turbine side and heat is radiated to the shaft of the turbine and the turbine.
The temperature will be as low as 800 ° C. For this reason, a temperature difference of about 400 ° C. is generated between the inner peripheral side and the outer peripheral side of the back plate, and the temperature gradient causes damage due to the maximum stress generated on the inner diameter side, thereby causing a secondary damage to the turbine rotor. there were.

The present invention has been made in view of such a conventional problem. During a high-load operation in which a maximum stress is generated in the back plate, the outer peripheral portion of the back plate is exposed to the compressor outlet air or the like. Cooled by cold air,
It is an object of the present invention to provide a ceramic gas turbine structure that can reduce the temperature gradient between the inner and outer circumferences, reduce stress, and prevent damage to the back plate.

[0007]

According to the present invention, a housing for supporting a turbine rotor shaft, a ceramic turbine shroud and a scroll disposed on the outer periphery of the turbine rotor are laminated on a ceramic back plate. In addition, in the ceramic gas turbine structure in which the cylindrical portion of the back plate is elastically pressed against the housing to regulate the relative relationship between the ceramic component and the turbine rotor, at least the back plate is provided on the outer peripheral side of the cylindrical portion. And a space surrounded by the housing and a housing, and a hole for introducing air from the compressor outlet or the outside of the housing is formed in the housing constituting the space.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a ceramic gas turbine structure according to an embodiment of the present invention. (First Embodiment) FIG. 1 is a diagram showing a first embodiment of a ceramic gas turbine structure according to the present invention.
In the present embodiment, the same components as those in the prior art shown in FIG. 10 are denoted by the same reference numerals, and redundant description is omitted here. First, the configuration will be described. In the ceramic gas turbine structure according to the first embodiment, as shown in FIG. 1, reference numeral 6-2 denotes a cooling air introduction hole, and high pressure such as compressor outlet air or an external air supply source. It is opened in the bearing housing 1 for introducing low-temperature air. The cooling air introduction hole 6-2 has the same path as the seal air introduction hole 6 or an independent path, and has a cross-sectional area of 0.1 to 5% with respect to the flow area of the turbine outlet. Have been. 10 is a ring plate,
It is configured to cover a ring-shaped groove formed in the turbine housing.

FIG. 2 and FIG. 3 are detailed views of the present embodiment. The ring plate 10 has a cross-sectional area of 0.01 to 0.5 times the cooling air introduction hole 6-2 at a pitch diameter of 0.7 to 1.3 times the outer diameter of the turbine rotor. Many small holes 10-1 are opened. Reference numeral 2 denotes a cylindrical part, and the end face of the cylindrical part on the back plate side is processed with high precision and is in contact with the outer peripheral side of the back plate with precisely processed surface, but there is no restriction in the radial direction. .
The end of the cylindrical part on the bearing housing 1 side is pressed against the bearing housing via a member 23 such as a heat insulating fiber having a contraction rate of 50 to 80%. Also,
The cylindrical part is made of a heat-resistant material such as ceramic.

Reference numeral 11 denotes a molded heat insulating material, which is configured to be attached to the inner diameter side of the back plate 3 as in the prior art. However, in this embodiment, as shown in FIG. Several slit portions 11-3 are formed on the circumference of the portion to be formed.

The outer diameter of the cylindrical portion 2-1 of the back plate 3 is 0.7 to 1.3 with respect to the outer diameter of the turbine rotor.
The bearing housing side, which is configured at the double position and in which this cylindrical portion fits, is similarly configured.

Next, the operation of the first embodiment will be described. In order to improve the efficiency, the ceramic gas turbine is used at an ultra-high temperature of 1300 ° C. or higher when the load is high at a turbine inlet temperature. FIG. 5 shows an example of the temperature state at this time. During operation with a high load of turbine inlet temperature 1300 ° C or higher,
For example, if the temperature of the bearing housing 1 is around 300 ° C.,
The temperature of the cylindrical portion 2-1 of the back plate 3 reaches 600 ° C. At this time, when a material such as silicon nitride is selected as the material of the back plate 3 and a heat-resistant material such as Hastelloy is used as the material of the bearing housing 1, the bearing housing has a smaller coefficient of thermal expansion than the bearing plate. 1 has a coefficient of thermal expansion of 5 to 6 times, the bearing housing 1 expands even if the temperature of the back plate 3 is nearly twice as high as that of the bearing housing 1, and the cylindrical portion of the back plate 3 and the bearing A gap is formed in the fitting portion A of the housing 1.

In the present embodiment, a small hole for introducing cooling air is provided on the outer peripheral side of the back plate 3 in the ring-shaped member, and a slit serving as a gap is formed in a contact portion between the back plate 3 and the heat insulating material. Therefore, if a gap is formed in the fitting portion A, the cooling air flows along the housing-side surface of the back plate 3 due to the pressure difference corresponding to the pressure loss from the compressor outlet to the turbine inlet or the external forced cooling air pressure. Flows. As a result, the outer periphery of the back plate 3 is cooled, and the cooling air heated by the heat of the outer periphery of the back plate 3 flows to the inner periphery of the back plate 3, so that the inner periphery of the back plate 3 is heated. Thereby, the temperature gradient between the inner and outer peripheries of the back plate 3 is reduced, the maximum stress generated in the back plate 3 is reduced, and the back plate 3 can be prevented from being damaged.

On the other hand, there is a case where a maximum stress is generated in another portion of the back plate 3 other than the above. FIG. 6 shows a temperature situation at the time of rapid acceleration of starting. At the time of starting rapid heating, the back plate 3 covered with a scroll
The portion exposed to the flow path of the back plate 3 is most susceptible to heat than the outer peripheral portion, and the temperature rise is faster at the inner circumference side exposed to the flow path of the back plate 3. At this time, the inner circumference has a higher temperature than the outer circumference, and the maximum stress occurs on the outermost circumference of the back plate 3. Further, when the remarkable rapid acceleration is frequently repeated, the strength of the ceramic member is reduced due to fatigue, and the back plate 3 may be damaged due to the reduced fatigue life strength. In such a situation, flowing the cooling air to the outer peripheral side regardless of the steady operation or the rapid acceleration of the start cools the outer periphery of the back plate 3, increases the temperature gradient of the inner and outer periphery, and reduces the thermal stress. Therefore, the life of the back plate 3 is shortened. In this respect, the present embodiment exhibits an excellent effect. In the starting state where the entire engine is cold, no gap is formed between the fitting portion A of the back plate 3 and the housing, no cooling air flows, and the high temperature Since the cooling air flows only during the operation, the life of the back plate 3 is not shortened by the thermal stress at the time of starting.

When the load on the engine is small, the temperature of the housing does not rise so much, the gap between the back plate 3 and the housing is small, and no cooling air flows.
Accordingly, at a low load, part of the compressor outlet air is not used as cooling air, so that there is an effect that a decrease in efficiency can be prevented.

(Second Embodiment) FIG. 7 is a view showing a ceramic gas turbine structure according to a second embodiment of the present invention. The differences from the first embodiment will be described. Small hole 10 penetrating in the axial direction of ring plate 10
−2, a turning angle α of 0 to 70 degrees with respect to the axial direction. As a result, the cooling air flowing on the outer surface of the back plate is swirled to make the flow smooth, to eliminate the non-uniformity of the local temperature distribution due to the cooling air, and to prevent the occurrence of local stress.

As described above, the second embodiment can prevent local stress from being generated when cooling air flows through the back plate during high-load operation.

(Third Embodiment) FIG. 8 is a view showing a ceramic gas turbine structure according to a third embodiment of the present invention. The differences from the first embodiment will be described. Reference numeral 15 denotes a cylindrical member made of ceramic. The back plate side of the cylindrical member is in contact with a surface that has been smoothly processed in the axial direction, and the cylindrical member is fitted so that the cylindrical member is on the outer peripheral side in the radial direction. It is configured. Further, the bearing housing 1 side of this cylindrical member has a tapered surface 15-1 formed in a conical shape, and is in contact with a surface 1-2 of the bearing housing having a tapered surface formed in a conical shape. The tubular member is fixed by being pressed against the back plate 3 and the housing by an elastic supporting force for attaching the ceramic component. Reference numeral 12 denotes a molded heat insulating material, and bolts 1 are inserted into several holes 12-1 formed in the heat insulating material.
4 and fixed to the bearing housing,
It is constituted by closing. Alternatively, it is fixed to the bearing housing 1 by another method such as an adhesive. Further, as shown in FIG. 9, no slit as in the first embodiment is formed on the back plate side surface of this molded heat insulating material, and furthermore, a gap is formed between the back plate and the heat insulating material. It is configured.

Next, the operation of the third embodiment will be described. When used under high load, due to the difference in thermal expansion between the bearing housing and back plate,
Even when the gap A occurs, the tapered surface 15-1 of the cylindrical member 15 and the tapered surface 1-2 of the bearing housing slightly move in the axial direction, but the radial axis is maintained. As a result, it is not necessary to maintain the axis of the bearing housing and the back plate with a molded heat insulating material that is difficult to achieve processing accuracy, and the heat insulating material can be fixed to the housing side without forming a slit between the back plate and the back plate. Since the cooling air passage can be formed, it is not necessary to form a slit on the surface of the heat insulating material having poor moldability. For this reason, there is an effect that the molding accuracy of the molded heat insulating material can be significantly reduced, and the production cost can be reduced. In addition, since the shaft cores of the bearing housing and the back plate can be maintained by using cylindrical ceramic parts that can be machined with high precision, the tip clearance between the turbine and the shroud can be made smaller, which can contribute to improving the efficiency of the gas turbine.

As described above, the third embodiment has the effects that the cost of the molded heat insulating material can be reduced and the turbine efficiency can be improved by maintaining the shaft core with high accuracy.

[0021]

As described above in detail, according to the present invention, the outer peripheral portion of the back plate is compressed by the compressor outlet air only during high-load operation in which the back plate is broken in the prior art. As a result, the temperature gradient between the inner and outer peripheries of the back plate is reduced, stress is reduced, and damage to the back plate can be prevented. Since cooling air does not flow at the time of rapid acceleration of the start and at the time of low load, there is an effect that a reduction in life due to thermal stress of the back plate and a decrease in engine efficiency at a low load due to flowing of cooling air can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a ceramic gas turbine structure according to the present invention.

FIG. 2 is a detailed view of the first embodiment.

FIG. 3 shows a ring plate 10 according to the first embodiment.
FIG.

FIG. 4 is a perspective view of a molded heat insulating material 11 according to the first embodiment.

FIG. 5 is a diagram showing a temperature situation under a high load.

FIG. 6 is a diagram showing a temperature situation at the time of rapid acceleration of starting.

FIG. 7 shows a ring plate 10 according to a second embodiment.
FIG.

FIG. 8 is a detailed view of the third embodiment.

FIG. 9 is a perspective view of a molded heat insulating material 12 according to a third embodiment.

FIG. 10 is a diagram showing a configuration of a conventional ceramic gas turbine structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bearing housing 2 Cylindrical part 3 Back plate 4 Scroll 5 Turbine 6 Seal air introduction hole 6-2 Cooling air introduction hole 7-1, 7-2 Seal ring 8 Elastic support structure 9 Engine housing 10 Ring plate 10-1, 10 -2 Small hole 11,12 Molded heat insulating material 13 Heat insulating material 14 Bolt 15 Cylindrical member 21 Turbine shroud 23 Member such as heat insulating fiber

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02C 7/18 F02C 7/18 E

Claims (6)

[Claims] 1. A housing for supporting a turbine rotor shaft, a ceramic turbine shroud and a scroll disposed on the outer periphery of the turbine rotor are laminated on a ceramic back plate, and a cylindrical portion of the back plate is elastically attached to the housing. In the ceramic gas turbine structure that regulates the relative relationship between the ceramic component and the turbine rotor, a space surrounded by at least a part of the back plate and the housing is formed on the outer peripheral side of the cylindrical portion. A ceramic gas turbine structure wherein a hole for introducing air from a compressor outlet or the outside of the housing is formed in a housing constituting a space. 2. The ceramic gas turbine structure according to claim 1, wherein said hole has an angle of 0 to 70 degrees with respect to an engine axial direction. 3. The ceramic gas turbine structure according to claim 1, wherein a ceramic tubular member is provided between an outer peripheral side of the back plate and the housing. 4. The ceramic gas turbine structure according to claim 3, wherein a conical tapered surface is provided on a contact surface between the cylindrical member and the housing. 5. The ceramic gas turbine structure according to claim 1, wherein a heat insulating material is interposed between the back plate and the housing, and a contact surface between the heat insulating material and the housing has a conical tapered surface shape. And a slit-shaped gap provided in the contact surface between the back plate and the heat insulating material and communicating from the inner periphery to the outer periphery and in the axial direction. 6. The ceramic gas turbine structure according to claim 1, wherein the heat insulating material interposed between the back plate and the housing is:
A ceramic gas turbine structure characterized by being fixed to a housing side by a method such as a bolt or an adhesive and forming a gap between a back plate and a heat insulating material.