JPH0886202A - Installation structure of ceramic blade - Google Patents

Abstract

PURPOSE: To realize the installation structure of a ceramic blade by which the ceramic blade exposed to high temperature gas can be stably attached to the peripheral part of a turbine disc having a comparatively large diameter without providing any mounting hole, and having excellent rotary balance and also including a small number of parts. CONSTITUTION: A ceramic blade 15 is fitted in and attached to the engagement grooves 12 of the outer circumferential part 11a of a metallic turbine disc 11 on its engagement projecting part 18. A contact part 13 brought in contact with one end of the platform part 17 of the turbine blade 15 fitted to and inserted in the engagement grooves 12 of the disc outer circumferential part 11a from the other disc end surface side, is provided on one disc end surface side of one side circumferential surface 11b between respective engagement grooves 12 of the disc 11. And, an engaging locking groove 14 to retain a presser ring 20 brought in contact with and presses the engagement protruding part 18 of the turbine blade 15 engaged with the engagement grooves 12, on the other side disc end surface, is formed on the other disc end surface of the disc outer circumferential part 11a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine for guiding a high temperature combustion gas to a ceramic turbine blade through a ceramic nozzle to obtain a rotational force. More specifically, a blade portion is provided on the outer peripheral side of a semi-circular cross-section platform portion. , A large number of ceramic turbine blades each provided with an engaging protrusion on the inner peripheral side of the ceramic blade to be fitted by fitting the engaging protrusions to the respective engaging grooves of the outer peripheral portion of the metal gas turbine disk Regarding mounting structure.

[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. Gas turbines have been attracting attention with the spread of cogeneration systems that can flexibly respond to load changes of heat and electricity and require only a short warm-up time, but ceramics are being used to further improve their thermal efficiency. The adoption of manufactured parts came to be considered. As one of the trials, a nozzle or turbine blade is manufactured using ceramics, and the high temperature combustion gas is not cooled from the combustor, and the ceramic turbine blade is passed through the gas passage in the ceramic scroll as it is through the ceramic nozzle. There is something that I tried to lead to. In such a ceramic gas turbine, the gas inlet temperature of the turbine is significantly increased to reach, for example, 1350 ° C., cooling loss can be significantly reduced, and further, in the regenerative heat exchanger. By recovering the heat by opposing heat exchange between the turbine exhaust gas and the intake air for the combustor, it has become possible to considerably improve the thermal efficiency (for example, about 42%).

However, although the dimensional accuracy of the ceramic parts has been secured, the ceramic parts can be positively used in parts such as turbine blades that require heat resistance, but compared with metal parts. It is brittle and has a very small coefficient of thermal expansion, so even when tightly tightening and combining ceramic parts and metal parts, they loosen or rattle at high temperatures or the tightening force increases and cracks into ceramic parts. I've come to often encounter the situation that said. Therefore, in fixing the ceramic component at a high temperature portion, it is necessary to hold it while avoiding an increase in thermal stress.

In consideration of the above points, in the ceramic gas turbine which has achieved the above-mentioned excellent thermal efficiency, as a prior art of the mounting structure for mounting the ceramic turbine blade to the outer peripheral portion of the metal disk, the actual open flat 1-14.
There is one disclosed in Japanese Patent No. 4401. In the mounting structure, as shown in FIG. 5, a ceramic turbine blade 50 having a blade portion 51, a platform portion 52, and an engaging protrusion 53 is provided at the outer peripheral portion of the metal turbine disk 55 at the engaging protrusion 53. Engaging groove 56
And a ceramic seal plate 61 is provided over the entire outer circumference of both side surfaces of the turbine disk 55, and the seal plate 61 is held from the outside by a fixed plate 62 to secure the turbine blade 50. It is restrained in the axial direction. Here, the seal plate 61 is divided into a plurality of pieces so as to withstand a large centrifugal stress during high-speed operation. The fixed plate 62 is a turbine disk 55.
It is fixed by bolts 63 and nuts 64 that pass through a plurality of mounting holes 57 that penetrate through the periphery of the. Further, cooling air is supplied from the supply hole 58 to the outer peripheral portion of the turbine disk 55 to reduce the heat load.

[0005]

Generally, in a small gas turbine, there is a possibility that the thermal efficiency is deteriorated because it is easily affected by leakage of working gas and frictional resistance. For this reason, it is advantageous to increase the number of revolutions to relatively reduce their influence and increase the specific output per unit flow rate of the working gas. Therefore,
Gas turbines using ceramic turbine blades are being manufactured at a peripheral speed of 570 m / s at the tip of the turbine blade, and even the turbine disk 55 made of a heat-resistant special alloy becomes high in temperature and When rotating at such a high peripheral speed, if the mounting hole 57 is provided in the circumferential direction at a peripheral portion having a relatively large diameter, a large centrifugal force may cause a large stress concentration around the mounting hole 57. The divided seal plate 61 and bolt 6
Since many members such as 3 and nut 64 are used, the number of parts is increased and the structure is complicated. On the other hand, there is also a disadvantage that the consumption of the cooling air is large due to the split seal plate 61.

The present invention solves the above-mentioned problems in the mounting structure of the ceramic parts at the high temperature and high peripheral speed. A ceramic blade mounting structure that can be stably mounted on a turbine disk without forming holes in the periphery of a large-diameter turbine disk, has excellent rotational balance, and has a simple structure with a small number of parts. Is intended.

[0007]

In order to achieve the above object, the ceramic blade mounting structure according to the present invention is a)
A large number of ceramic blades, each having a blade portion on the outer peripheral side of the semi-circular cross-section platform portion and an engaging protrusion portion on the inner peripheral side, are provided on the outer peripheral portion of the metal turbine disk by the engaging protrusion portions. In a mounting structure of a ceramic blade that is fitted into a mating groove, and b) is fitted to one disk end surface side between the engaging grooves of the turbine disk and the other disk end surface side to the engaging groove of the disk outer peripheral portion. An abutting portion that comes into contact with one end of the platform portion of the blade to be inserted is provided, and c) the other disc end surface of the turbine disc outer peripheral portion, the engagement of the blade fitted in the engaging groove of the turbine disc outer peripheral portion. The retaining groove of the pressing ring that is pressed against the mating protrusion is formed.

According to a second aspect of the present invention, it is preferable that the turbine disk is provided with a cooling air supply hole which is opened at a bottom of each of the engagement grooves and which supplies cooling air.

Further, as described in claim 3, a snap ring made of a heat-resistant alloy such as Waspaloy can be used for the pressing ring.

Further, as described in claim 4, the retaining ring engaging groove engages with the outer peripheral edge engaging portion and the inner peripheral side engaging portion of the retaining ring, respectively. It is preferable to obtain a larger locking force by constructing the two locking grooves.

Further, according to a fifth aspect of the present invention, in the engagement groove, one disc end face side of the abutting portion provided with a protrusion is higher than the axis line, and the other disc end face of the pressing ring is locked. It is more preferable that the side is formed on the outer peripheral portion of the turbine disk in a low inclined state so that the load is not applied to the pressing ring during high speed rotation.

[0012]

By using the ceramic blade of the present invention having the above-mentioned structure, the high temperature combustion gas generated in the combustor or the like is passed through the gas passage made of ceramic such as the ceramic scroll to obtain high temperature without passing through the cooling air. By directly introducing the same to the ceramic blade through the ceramic nozzle, the cycle temperature can be increased, the cooling loss can be greatly reduced, and the heat efficiency can be greatly improved together with the exhaust heat recovery to the high temperature combustion gas. By the way, the temperature of the combustion gas introduced to the turbine, which was conventionally suppressed to around 960 ° C, can now be increased to about 1350 ° C without the use of ceramics. It has become possible to significantly improve the thermal efficiency (up to around 42%) by recovering the exhaust heat to the intake air for the introduction combustion gas generation using a heater or the like. Each of the ceramic blades is fitted into and attached to the engaging groove of the outer peripheral portion of the metal disk at the engaging projection portion thereof, and is configured to withstand a large centrifugal force during high speed rotation.

Further, the axial restraint of the ceramic (turbine) blade is such that the contact portion provided on the outer peripheral surface between the engaging grooves of the metal disk on one disk end surface side is brought into contact with the disk from the other disk end surface side. The one end of the platform portion of the ceramic blade fitted into the engagement groove of the outer peripheral portion is brought into contact with the other end portion of the disk, and the engaging protrusion portion and / or the platform portion of the blade is held by the holding ring locked to the other disc end surface side of the outer peripheral portion of the disc This is achieved by pressing the other end of. The pressing ring is attached using a locking groove formed on the other disk end surface of the disk outer peripheral portion.

According to a second aspect of the present invention, the turbine disk is provided with a cooling air supply hole that opens to the bottom of the engagement groove formed on the outer peripheral portion of the turbine disk. The cooling air is supplied into the engagement groove by utilizing the pressure difference between the upstream side and the downstream side of the turbine, cools the outer peripheral portion of the turbine disk to reduce the heat load, and the high temperature combustion gas flows into the engagement groove. The flow of the cooling air is blocked by the holding ring, and the amount of cooling air consumed is also small.

When the pressing ring is made of a snap ring made of a heat-resistant alloy as in claim 3, the pressing ring can be easily attached and detached. Further, claim 4
As described above, when the holding ring locking groove is formed of two locking grooves on the outer peripheral side and the inner peripheral side that respectively engage with the outer peripheral edge locking portion and the inner peripheral side locking portion of the pressing ring, , The holding force of the presser ring can be increased.

According to a fifth aspect of the present invention, the engagement groove is inclined in such a state that one disc end face side provided with the abutting portion is high with respect to the axis and the other disc end face side with which the pressing ring is locked is low. If formed on the outer peripheral portion of the disk, the ceramic blade will be urged toward the abutting portion on the outer peripheral surface of the disk by the axial component force of the centrifugal force during high-speed rotation.
The pressing ring is less likely to be loaded.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a ceramic blade mounting structure according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a vertical cross-sectional view of a main part of a ceramic gas turbine showing a ceramic turbine blade mounting structure of a gas turbine according to an embodiment of the present invention, and FIG. 2 is a partial perspective view taken along the line II in FIG. 3 is a front view of a turbine blade pressing ring used in the same embodiment, and FIG. 4 is an enlarged vertical sectional view taken along the line IV-IV in FIG.

In FIG. 1, the gas turbine according to this embodiment is suitable for a cogeneration system that can flexibly cope with load fluctuations of heat and electricity and requires only a short warm-up operation time, such as a ceramic combustor. The high temperature combustion gas G generated in 1 is guided from the gas passage P of the ceramic scroll 5 through the ceramic gas generator turbine nozzle 6 and the ceramic turbine blade 8 to the ceramic power turbine blade 15 through the ceramic power turbine nozzle 9. I am trying. The turbine rotor disk 7 is made of ceramic integrally with the turbine blade 8 because the outer diameter is relatively small. On the other hand, since the power turbine rotor 10 has a relatively large outer diameter, it is difficult to integrally form the power turbine rotor 10 with ceramics. Therefore, in the power turbine rotor 10, the turbine disk 11 is made of a metal material such as a heat resistant alloy, and the outer peripheral portion 1 thereof is
A large number of ceramic turbine blades 15 are evenly planted in 1a.

In this ceramic gas turbine, since the rotational speed of the power turbine rotor 10 is increased, the torque that the turbine blade 15 takes is reduced, which is advantageous for the ceramic turbine blade 15. However, since the centrifugal force is increased by the amount of exposure to high-temperature gas and the increase in rotation speed, the unique ceramic blade mounting structure 1 of this embodiment is important.

As shown in FIGS. 1 and 2, in this blade mounting structure 1, a ceramic turbine blade 15 has a blade portion 16 on the outer peripheral side of a semicircular arc-shaped platform 17 and an inner peripheral side of the platform portion 17. The engaging protrusions (dovetails) 18 are respectively provided, and the outer peripheral portion 11 of the metal turbine disk 11 is provided at the engaging protrusions 18.
It is fitted in and attached to each of the engaging grooves 12 of a, and the outer peripheral side bulging portion (tongue portion) 12a of the engaging groove 12 prevents the engaging groove 12 from being separated outward in the radial direction.

The turbine disk 11 is fitted and inserted into the outer peripheral surface 11b between the engaging grooves of the turbine disk 11 on one disk end surface side (upstream side) and on the other disk end surface side (downstream side). An abutting portion 13 that abuts on an upstream end of the platform portion 17 of the turbine blade 15 is provided. Platform part 1 of turbine blade 15
No. 7 is inclined because the height of the blade portion 16 increases toward the downstream side in response to the expansion of the working gas G. Correspondingly to this, the turbine disk outer peripheral surface 11b and the engaging groove 12 are higher on the upstream side where the abutting portion 13 is projected than the axis X, and the turbine blade pressing ring 20 described later is locked. The downstream side is at a low inclination. Therefore, the turbine blade 15 is biased to the upstream contact portion 13 on the turbine disk outer peripheral surface 11b by the axial component force of the centrifugal force during high-speed rotation, and the pressing ring 20 is not loaded. become.
The abutment portion 13 is provided on the outer peripheral surface 11b between the engagement grooves 12 and the platform portion 1 for preventing heat transfer to the turbine blade 15.
It also serves to prevent the high-temperature working gas G from flowing into the gap C between the high-temperature working gas 7 and the gap 7.

On the other hand, on the downstream end surface of the turbine disk outer peripheral portion 11a, on the upstream side, the engaging projection 18 of the turbine blade 15 fitted and engaged in each engaging groove 12 of the disk outer peripheral portion 11a is provided. A locking groove 14 for holding the pressing ring 20 that abuts and presses is formed. The retaining ring locking groove 14 is composed of two retaining grooves 14a and 14b for respectively retaining the outer peripheral edge retaining portion 24a and the inner peripheral side retaining portion 24b of the retaining ring 20. Although the locking groove 14 has a portion having a large curvature in the axial direction, it has a small curvature in the circumferential direction, so that centrifugal stress (hoop stress) is concentrated even if the turbine disk 11 rotates at a high speed. Stable presser ring 20 that does not raise and does not use mounting holes
Can hold.

Further, the gas turbine disk 11 penetrates between the bottom 12a of each engaging groove 12 of the outer peripheral portion 11a and the disk intermediate portion 11c on the downstream side of the disk and is opened, and is engaged from the downstream intermediate portion 11c side. Cooling air supply holes 19 are formed radially to supply cooling air to the mating groove bottom 12a with a pressure difference. The cooling air serves to cool the turbine disk 11 itself, the outer peripheral portion 11 a and the pressing ring 20 to reduce the heat load, and to prevent the hot working gas G from flowing into the engagement groove 12. When the cooling air flows out from the engaging groove 12, the groove 12 is closed by the pressing ring 20 on the downstream side and receives the resistance of the working gas flow on the upstream side.
Its consumption is relatively small. Incidentally, the supply source of the cooling air is provided by being introduced into the rotor shaft surrounding space from the pressure air outlet part of the air compression blower rotatably driven by the turbine rotor 7 through the turbine rotor shaft labyrinth part.

As shown in detail in FIGS. 3 and 4, the holding ring 20 is a snap ring made of a heat-resistant alloy such as Waspaloy, and is elastic in the radial direction by the slits 21 which are formed by facing slopes overlapping each other. It can be scaled up and down slightly. Further, the presser ring 20 has the slit 2
A tab 22 having a hole 22a that can be engaged with a claw of an opening / closing tool used when mounting or removing the locking groove 14 is provided on both inner peripheral portions of 1 so as to face the tabs 22. A tab 23 having a hole 23a for engaging a claw of a similar tool is provided in a protruding manner for supporting the pressing ring 20 when mounting or dismounting and for rotational balance. Further, as described above, as the locking portion 24 of the ring 20, the outer peripheral edge locking portion 24a and the inner peripheral side locking portion 24b.
And are projected to the outside in a complementary manner. Locking groove 1
The pressing ring 20 mounted on the No. 4 tends to open due to centrifugal force when the turbine disk 11 rotates at a high speed,
Since the locking portions 24a and 24b face outward, they are more strongly received by the locking groove 14. When this pressing ring 20 is attached to the disk end surface on the downstream side of the turbine disk outer peripheral portion 11a, the high temperature gas G flows through the engagement groove 12 of the turbine disk outer peripheral portion 11a, similarly to the seal plate described in the conventional example. To prevent the turbine disk outer peripheral portion 11a from overheating.

The holding ring 20 may be formed of ceramics of the kind used for coil springs instead of the metal material such as the heat resistant alloy, and the shape memory of various shapes may be used instead of the snap ring shape. It may be formed of a ring made of an alloy.

[0027]

As described above, according to the ceramic blade mounting structure of the present invention, (1) the metal turbine disk having a relatively large diameter is exposed to the high temperature gas and swirls at a high peripheral speed. It can be mounted stably without concentration of centrifugal stress on the periphery of, and has excellent rotation balance, has a small number of parts, and has a simple structure and excellent durability.

(2) In the mounting structure according to the second aspect, the cooling air is provided in the engagement groove formed in the outer peripheral portion of the turbine disk so that the cooling air is provided in the engagement groove. Is supplied to cool the outer peripheral portion of the turbine disk to reduce the heat load, and it is possible to prevent the hot working gas from flowing into the engaging groove, and the consumption of the cooling air is relatively small. Complete.

(3) In the mounting structure according to the third aspect of the present invention, since the holding ring is made of the snap ring made of a heat-resistant alloy, the holding ring can be easily attached and detached, and the high temperature working gas can be engaged in the engaging groove. Can be prevented from flowing through.

(4) In the mounting structure according to the fourth aspect, the retaining groove for the presser ring is provided on the outer peripheral side and the inner peripheral side, which engage with the outer peripheral edge retaining portion and the inner peripheral side retaining portion of the retaining ring, respectively. If it is composed of two locking grooves, the locking force of the pressing ring can be increased.

(5) In the mounting structure of claim 5, the engaging groove is
Centrifuges during high-speed rotation are formed by forming the outer peripheral portion of the gas turbine disk in such a state that one end surface of the disk where the abutment part is provided is high with respect to the axis and the other end surface of the disk on which the pressing ring is locked is inclined low. Due to the axial component of the force, the ceramic blade tends to be urged to the abutting portion on the outer peripheral surface of the turbine disk, so that the pressing ring is hardly loaded.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a ceramic gas turbine showing a mounting structure of a ceramic blade according to an embodiment of the present invention.

FIG. 2 is a partial perspective view taken along the line II in FIG.

FIG. 3 is a front view showing a pressing ring for turbine blades used in the embodiment of FIG.

FIG. 4 is an enlarged vertical sectional view taken along the line IV-IV in FIG.

FIG. 5 is a vertical cross-sectional view of a main part showing a ceramic blade mounting structure according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic blade mounting structure 11a Disk outer peripheral part 11b Outer peripheral part upper surface 12 Engagement groove 12a Engaging groove bottom 13 Abutment part 14 Locking groove 14a Outer peripheral side engaging groove 14b Inner peripheral side engaging groove 15 Turbine blade 16 Blade part 17 Platform part 18 Engagement protrusion part 19 Cooling air supply hole 20 Holding ring (snap ring) 24a Outer peripheral edge locking part 24b Inner peripheral side locking part G High temperature combustion gas P Gas passage X Axis

Claims (5)

[Claims] 1. A large number of ceramic blades each having a blade portion on the outer peripheral side of a semi-circular cross-section platform portion and an engaging protrusion portion on the inner peripheral side, the engaging protrusion portions of a metal turbine disk In a mounting structure of a ceramic blade fitted and fitted in each engaging groove of an outer peripheral portion, engagement of the disk outer peripheral portion from one end surface side of the other disk between the engaging grooves of the turbine disk and the other end surface side of the disk. While providing an abutting portion that abuts one end of the platform portion of the blade that is fitted into the groove, on the other disc end surface of the turbine disc outer peripheral portion,
A structure for mounting a ceramic blade, characterized in that a retaining ring for a pressing ring that abuts and holds an engaging protrusion of the blade fitted in an engaging groove of the outer peripheral portion of the turbine disk is formed. 2. The mounting structure for a ceramic blade according to claim 1, wherein the turbine disk is provided with a cooling air supply hole which is provided at a bottom of each of the engagement grooves and which supplies cooling air. 3. The mounting structure for a ceramic blade according to claim 1, wherein the pressing ring is a snap ring made of a heat resistant alloy. 4. The retaining ring for a retaining ring is composed of two retaining grooves on an outer peripheral side and an inner peripheral side, which engage with an outer peripheral edge retaining portion and an inner peripheral retaining portion of the retaining ring, respectively. The mounting structure for a ceramic blade according to claim 1. 5. The outer peripheral portion of the turbine disk in the inclined state in which the engagement groove is inclined on one disk end surface side provided with a contact portion with respect to the axis and on the other disk end surface side with which the pressing ring is locked is low. The mounting structure for a ceramic blade according to claim 1 or 2, wherein