JPH07332002A - Ceramic gas turbine rotor - Google Patents

Abstract

(57) [Abstract] [Purpose] It is necessary to counter the torque fluctuation during operation of the ceramic shaft that rotates at high speed among the components of the gas turbine and to prevent it from loosening due to the difference in thermal expansion from the metal shaft. (EN) Provided is a ceramic gas turbine rotor which secures a tightening force, maintains a stable connected state, and is easy to connect the both, and which can be securely connected. [Structure] The ceramic shaft portion 11 has a coupling end portion 11a.
In the above, it is joined to the cup-shaped portion 25 of the joint shaft 21 by brazing or sintering. Labyrinth ring 31 provided with labyrinth seal 32 separately from joint shaft 21
Is fastened to the shoulder portion 25 c of the cup-shaped portion 25 so as to surround the outside of the cup-shaped portion 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic gas turbine rotor having a structure in which a ceramic shaft portion integrated with a ceramic turbine portion is connected to a metal rotor shaft.

[0002]

2. Description of the Related Art Due to recent rapid progress in molding and firing technology for ceramics, ceramics have been manufactured from various heat resistant structural parts to working parts such as internal combustion engine pistons that require high accuracy. Even in gas turbines, the adoption of ceramic parts has attracted attention due to the spread of cogeneration systems that can flexibly respond to heat and electric load fluctuations and require only a short warm-up time, and further improve thermal efficiency. As a result, the adoption of ceramic parts came to be considered for practical use. As one of the attempts, a nozzle, a turbine blade and a rotor are manufactured by using ceramic, and the high temperature combustion gas is not cooled from the combustor and is passed through the gas passage in the ceramic scroll as it is, and the turbine blade is passed through the nozzle. There is something that I tried to lead to. In such a ceramic gas turbine, the turbine thermal efficiency is improved by improving the turbine inlet temperature, performing the above-mentioned non-cooling, and performing heat recovery by opposing heat exchange between the turbine exhaust gas and the combustor intake air in the regenerative heat exchanger. It has become possible to greatly increase it.

However, at this stage, the parts that can be made of ceramics are limited in size and shape, and therefore, ceramic parts are used only at the portions that come into direct contact with high temperature combustion gas. Recently, for example, it has become possible to integrally manufacture a turbine of a GGT (gas generator turbine) rotor having an outer diameter smaller than that of a PT (power turbine) rotor by using ceramics. It is impossible to manufacture the shaft from ceramic, and it is currently formed from a metal material. Therefore, it is necessary to integrally connect the ceramic turbine to the tip of the metal rotor shaft. In the case of this type of coupling, the tip of the rotor shaft is formed into a cup-shaped portion, and the size of the cup-shaped portion is made slightly smaller than the shaft portion of the turbine blade portion, and the cup-shaped portion is heated and expanded. There has been proposed and implemented a method in which the shaft portion of the turbine blade portion is inserted in such a state, cooled, and contracted, so-called shrink-fitting and brazing are used for connection.

[0004]

However, although the dimensional accuracy of the ceramic parts has been secured to some extent, the ceramic shaft is fragile and has a very small thermal expansion coefficient as compared with the metal parts. Although it is difficult to tighten the parts with a metal cup-shaped part by caulking or join them by brazing, it is possible to join the ceramic shaft part and the cup-shaped part of the metal rotor shaft by shrink fitting. In the case of failure, the following inconvenience occurs.

That is, there is a possibility that the cup-shaped portion may expand due to being heated in contact with a high-temperature combustion gas or in a combustion gas atmosphere during use, resulting in loosening of the coupled state. In particular, in order to prevent the lubricating oil from flowing out of the bearing for rotatably supporting the rotor shaft near the root of the ceramic turbine part, that is, near the joint with the rotor shaft made of metal, due to the structure of the gas turbine. It is necessary to install a labyrinth seal, but since the labyrinth seal is in contact with the non-rotating part, the frictional heat generated between the two will heat the vicinity of the joint with the rotor shaft and the temperature may rise. .

The present invention has been made in view of the above points,
It is intended to eliminate the above-mentioned inconvenience in coupling a ceramic shaft portion integrally formed with a turbine blade portion and a metal rotor shaft, and to operate a ceramic shaft portion rotating at high speed among gas turbine component parts. It is an object of the present invention to provide a ceramic gas turbine rotor that can counteract the torque fluctuation of (1) and can be retained in a stable coupled state by securing a necessary tightening force without being loosened due to a difference in thermal expansion with a metal shaft.

[0007]

To achieve the above object, a ceramic gas turbine rotor according to the present invention comprises: a) a cup-shaped portion in which a ceramic shaft portion integral with a ceramic turbine portion is provided at the tip of a metal rotor shaft. In a ceramic gas turbine rotor having a structure connected to, b) the cup-shaped portion is provided at the tip of a low expansion alloy joint shaft that is separate from the rotor shaft, and this shaft joint is connected to the rotor shaft, c )
The ceramic shaft portion is joined to the cup-shaped portion at the tip of the joint shaft by shrink fitting or brazing, and d) an annular labyrinth seal is attached around the cup-shaped portion.

As described in claim 2, e) it is desirable to mount an annular body provided with the annular labyrinth seal around the root portion of the cup-shaped portion.

According to a third aspect of the present invention, f) the joint shaft is formed of a cylindrical shaft, and air passage holes communicating with the hollow interior are formed near both ends of the joint shaft to form a joint shaft. It is more preferable that the inside is formed as a flow passage for cooling air.

As described in claim 4, g) it is preferable that an air passage hole is bored through the annular body in the radial direction.

As described in claim 5, h), in addition to the annular body, a plurality of annular bodies including an impeller for a compressor having an annular labyrinth seal are continuously provided around the joint shaft and the rotor shaft. Are fixedly arranged, and the annular bodies are fixed by tightening between the cup-shaped portion and a nut screwed to the proximal end side screwed portion of the rotor shaft, and the rotor shaft and the rotor shaft are integrated with each other. While rotating each annular body, a part of the annular body can be rotatably supported by a bearing arranged between the labyrinth seals.

[0012]

According to the ceramic gas turbine rotor of the present invention constructed as above, the ceramic shaft portion of the ceramic turbine portion of the ceramic turbine rotor is fitted into the cup-shaped portion at the tip of the rotor shaft to couple the two. By using this ceramic gas turbine rotor in a gas turbine, it is possible to introduce high-temperature combustion gas from a combustor to a turbine blade through a ceramic scroll or nozzle without cooling it in the middle, at high temperature. Therefore, the cooling loss can be significantly reduced, and it is possible to dramatically improve the turbine thermal efficiency together with the significant reduction of the cooling loss and the exhaust heat recovery to the high temperature combustion gas. However, during operation, the ceramic turbine part and the rotor shaft rotate together, and the labyrinth seal around the cup-shaped part at the tip of the rotor shaft also rotates and friction heat is generated between the non-rotating part where this seal contacts. However, since both rotate at high speed, the joint between them is cooled by the surrounding air, and the temperature rise is minimized,
The joint shaft to which the labyrinth seal is attached is made of a low-expansion alloy that is separate from the rotor shaft, and the cup-shaped part does not expand easily even when heated, so the joint between the ceramic turbine part and the rotor shaft may loosen. Absent. In addition, since the cup-shaped portion is provided on the separate joint shaft, its processing is easy.

A gas turbine rotor is generally provided with a bearing for rotatably supporting the rotor shaft, and a labyrinth seal is attached near the bearing as described above so that the lubricating oil of the bearing does not flow out. In the rotor of Item 2, since the annular body provided with the labyrinth seal, which is separate from the metal joint shaft, is provided around the base of the cup-shaped portion of the joint shaft, the labyrinth seal is rubbed during operation to generate heat. However, the heat is not directly transmitted to the joint between the ceramic shaft and the metal joint shaft, and the influence of thermal expansion can be avoided to secure the bonding strength by sintering or brazing.

In the rotor according to the third aspect of the present invention, the cooling air is circulated in the metal joint shaft to cool the cup-shaped portion, so that the temperature in the vicinity of the cup-shaped portion can be lowered during the operation of the turbine. The coupling state between the ceramic shaft portion and the cup-shaped portion of the metal joint shaft does not loosen.

According to the rotor of claim 4, the cooling air is circulated in the vicinity of the labyrinth seal having the highest temperature due to frictional heat to cool the labyrinth seal and its periphery to lower the temperature. The joint with the joint shaft is cooled more effectively, and the looseness of the joint is reliably prevented.

In the rotor according to the fifth aspect of the present invention, the combustion gas passing through the turbine blades rotates the rotor, and at the same time, the impeller for the compressor can compress and send combustion air or the like. The annular body attached around the rotor shaft is fastened with the cup-shaped portion on the tip end side and the nut on the base end side so as to be integrally rotatable by so-called frictional force, so that a plurality of annular bodies can be fixed at the same time.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The ceramic gas turbine rotor of the present invention will now be described in detail below by way of embodiments with reference to the accompanying drawings.

FIG. 1 is a longitudinal cross-sectional view of a main portion of a gas turbine showing a coupling structure of a ceramic rotor shaft portion of a ceramic gas turbine rotor according to an embodiment of the present invention and a metal rotor shaft to which a compressor impeller is attached. FIG. 2 is an enlarged vertical sectional view of an essential part of the gas turbine of FIG. 1, FIG. 3 is a perspective view showing a combination state of a cup-shaped part of a joint shaft and a labyrinth ring, and FIG. 4 is a ceramic gas turbine rotor. Is a central vertical cross-sectional view showing the whole of FIG.

As shown in FIGS. 1 to 4, the gas turbine according to this embodiment is suitable for a cogeneration system which can flexibly cope with load fluctuations of heat and electricity and requires only a short warm-up time. A high temperature combustion gas G generated in a ceramic combustor or the like is introduced from a ceramic nozzle 6 to a ceramic turbine blade 7 via a ceramic scroll 5. This gas turbine has 2
The stage has separate turbine rotors, and the GGT (turbine) rotor 1 of the first stage rotatably drives a compressor (compressor) 4 that supplies pressurized combustion air to a combustor, and the GGT (turbine) rotor of the second stage of the second stage. A PT (turbine) rotor (not shown) rotationally drives a generator.

Here, the GG turbine rotor 1 having a coupling structure of the ceramic shaft portion 11 of the ceramic turbine portion 10 and the metallic rotor shaft 24, which is one of the features of the present invention.
~ The rotating system up to the compressor 4 will be described.
The turbine blade 7 is integrally formed of ceramic around a GG turbine rotor body (ceramic turbine portion) 10. Further, the GG turbine rotor body 10 is integrally provided with the ceramic shaft portion 11.

A cylindrical metallic joint shaft 21 is screwed onto the tip of the metallic rotor shaft 24 and is connected so as to be integrally rotatable. A cup-shaped portion 25 that bulges in the radial direction is formed at the tip of the joint shaft 21. As shown in Fig. 4, the rotor shaft 2
4, the compressor rotor body (impeller) 41
Is loosely inserted, and the rotor shaft 24 is
Tighten with the nut 50 of the threaded portion of the base of the joint shaft 21, and the compressor rotor body 41 is loosely inserted around the joint shaft 21 toward the cup-shaped portion 25 of the joint shaft 21, together with the spacer 28 and the labyrinth ring 31. I have tightened the sheets. In order to reliably transmit the rotational torque from the GG turbine rotor body 10, the compressor rotor body 41 and the sleeve body 23 mesh with each other at the face gear 42, and the sleeve body 23 and the joint shaft 21 mesh at the spline 22. The rotation system extending from the GG turbine rotor body 10 to the compressor rotor body 41 includes a suction side bearing 51 of the compressor 4 and the GG turbine rotor body 4.
It is rotatably supported by the first side bearing 29.

Ceramic GG turbine rotor body 10
The ceramic shaft portion 11 is joined to the cup-shaped portion 25 of the joint shaft 21 at the joint end portion 11a thereof by brazing or sintering. Further, the hollow inside of the joint shaft 21 is formed in the cooling air passage 21a, and from the pressure air discharge portion 4a of the compressor 4, as shown by an arrow A1, from the through hole 21b formed on the base side of the joint shaft 21. Cooling air is supplied to the air passage 21a. Further, since a plurality of through holes 25b are also formed near the cup-shaped portion 25, the joint between the ceramic shaft portion 11 and the cup-shaped portion 25 is forcibly cooled. Therefore, with its forced cooling,
It is cooled by heat exchange cooling with the surrounding air due to the high speed rotation, so that the coupled end portion 11a of the ceramic shaft portion 11 maintains the coupled state with the cup-shaped portion 25 of the joint shaft 21. Further, in order to enhance the cooling of the joint portion between the ceramic shaft portion 11 and the cup-shaped portion 25, a plurality of air circulation holes 31a penetrating the labyrinth ring 31 in the radial direction are formed so that cooling air having a higher pressure can be cooled. It is configured so that it can be directly sprayed onto the 25.

The joint shaft 21 is supported by a bearing 29 near its cup-shaped portion 25, and an inner race 29a of the bearing 29 is provided around the sleeve shaft 23 meshed with the joint shaft 21 at a spline 22 on the GG turbine rotor side. It is integrated. Since the lubricating oil is supplied to the bearing 29 from the supply pipe P1, the annular labyrinth seal 32 seals the lubricating oil against the lubricating oil.

The labyrinth seal 32 is attached to the outer peripheral surface of the labyrinth ring 31 as an annular body so as to push back the lubricating oil contained therein to the compressor side via air. The labyrinth ring 31 is close to the central shroud 3 of the gas turbine casing,
Although it may lightly contact and generate heat during rotation, the heat is not directly transmitted to (the cup-shaped portion 25 of) the joint shaft 21. This is a labyrinth ring 3 separate from the joint shaft 21.
1 is provided so as to surround the outer side of the cup-shaped portion 25, and the labyrinth ring 31 is fastened to the shoulder portion 25c of the cup-shaped portion 25. The labyrinth seal 32 also has an arrow A2 from the discharge portion 4b of the diffuser 43 that converts the dynamic pressure of the discharge air of the compressor 4 into a static pressure.
As shown by, cooling air is supplied through the radial hole 3a of the shroud 3 to prevent heat transfer and push back the lubricating oil that has entered to the compressor 4 side. The labyrinth seal 36 having the same structure as that of the compressor rotor body 41 and the sleeve shaft 23
It is also provided in the vicinity of the meshing portion of the face gear 42 with.

The tip portion of the joint shaft 21 has a cup-shaped portion 25 having a circular cross section, and the ceramic shaft portion 11 has a cylindrical shape corresponding thereto, but its corners are rounded so as not to cause stress concentration. The concavities and convexities may be formed on the coupling peripheral surface of the cup-shaped portion 25 and the ceramic shaft portion 11 so as to mesh with each other.

Further, as in the above embodiment, the rotor shaft 24
Instead of providing the cup-shaped portion 25 on the joint shaft 21 connected to, the cup-shaped portion 25 may be provided on the tip of the rotor shaft 24.

[0027]

As is apparent from the above description,
The ceramic gas turbine rotor of the present invention has the following excellent effects.

(1) The connecting portion between the ceramic shaft portion integrally formed with the turbine blade portion and the metal rotor shaft is not loosened, the required tightening force is secured, and the stable connected state is maintained. . Also, because it is provided at the tip of a separate joint shaft that connects the cup-shaped portion at the tip of the rotor shaft, the cup-shaped portion can be easily formed (worked), and the materials of the rotor shaft and the joint shaft can be changed. There is. .

(2) In the rotor of claim 2, since the rotor shaft (or the joint shaft) is provided with a separate labyrinth ring so as to surround the outside of the cup-shaped portion, the labyrinth seal rubs during operation. Even if the heat is generated, the heat is not directly transmitted to the joint between the ceramic shaft portion and the cup-shaped portion, the influence of thermal expansion can be avoided, and the joint strength due to the sintering can be stably ensured.

(3) In the rotor according to the third aspect, cooling air is circulated in the metallic joint shaft to cool the cup-shaped portion, so that the temperature near the cup-shaped portion can be lowered during operation of the turbine. As a result, the coupling state between the ceramic shaft portion and the cup-shaped portion of the metal joint shaft does not loosen.

(4) In the rotor according to claim 4, since the labyrinth seal having the highest temperature due to frictional heat and its surroundings are cooled by the cooling air, the cooling of the joint portion between the ceramic shaft portion and the joint shaft is further strengthened. Therefore, the looseness of the coupled state is reliably prevented.

(5) In the rotor according to the fifth aspect, the annular body mounted around the rotor shaft is fastened with the cup-shaped portion on the tip end side and the nut on the base end side so as to be integrally rotatable by so-called frictional force. As a result, a plurality of annular bodies can be fixed at the same time, and can be easily attached and detached.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a gas turbine showing a coupling structure of a ceramic rotor shaft portion of a ceramic gas turbine rotor according to an embodiment of the present invention and a metal rotor shaft to which a compressor impeller is attached. Is.

FIG. 2 is an enlarged vertical sectional view of a main part of the gas turbine of FIG.

FIG. 3 is a perspective view showing a combined state of a cup-shaped portion of a joint shaft and a labyrinth ring.

FIG. 4 is a central longitudinal sectional view showing the entire ceramic gas turbine rotor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic turbine rotor 7 Turbine blade 10 Turbine part 11 Ceramic shaft part 21 Joint shaft 25 Cup shape part 25b Cooling air passage 31 Labyrinth ring (annular body) 31 Labyrinth seal

Claims (5)

[Claims] 1. A ceramic gas turbine rotor having a structure in which a ceramic shaft portion integrated with a ceramic turbine portion is connected to a cup-shaped portion provided at the tip of a metal rotor shaft, wherein the cup-shaped portion is the rotor shaft. Provided at the tip of a separate low-expansion alloy joint shaft, this shaft joint is connected to the rotor shaft, the ceramic shaft portion is joined to the cup-shaped portion of the joint shaft tip by shrink fitting or brazing, A ceramic gas turbine rotor, wherein an annular labyrinth seal is attached around the cup-shaped portion. 2. Around the root of the cup-shaped portion,
The ceramic gas turbine rotor according to claim 1, wherein an annular body having the annular labyrinth seal is attached. 3. The joint shaft is formed of a cylindrical shaft, and air passage holes communicating with the hollow inside are formed near both ends of the joint shaft, and a cooling air flow passage is formed in the joint shaft. The ceramic gas turbine rotor according to claim 1 or 2, wherein the ceramic gas turbine rotor is configured as described above. 4. The ceramic gas turbine rotor according to claim 2, wherein an air passage hole is bored through the annular body in a radial direction. 5. In addition to the annular body, a plurality of annular bodies including a compressor impeller provided with an annular labyrinth seal are continuously arranged around the joint shaft and the rotor shaft,
The annular bodies are fixed by tightening between the cup-shaped portion and a nut screwed into the proximal end side screwing portion of the rotor shaft, and the annular bodies are rotated integrally with the rotor shaft. And a part of the annular body is rotatably supported by a bearing arranged between the labyrinth seals.
The ceramic gas turbine rotor according to any one of items 1 to 5.