JPH11200893A - Coolant recovery type gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coolant recovery type gas turbine performing efficiently closed cooling of a peripheral side end wall of a stationary blade, a blade part, and an internal peripheral side end wall, also improving performance and reliability. SOLUTION: In a coolant recovery type gas turbine having a cooler 4 extracting a compressor delivery fluid of the gas turbine as a coolant cooled, boost compressor 5 stepping up pressure of cooled coolant, supply system 73 supplying a pressure stepped up coolant in an internal cooling flow path of a stationary blade 6, and a recovery system 74 recovering coolant discharged from the internal cooling flow path of the stationary blade 6 in a compressor delivery part of this gas turbine, also supplying a fluid between the adjacent stationary blades to be formed so as to perform a seal between the adjacent stationary blades 6, a seal fluid supply system 75 is provided, which forms all of the pressure stepped up refrigerant so as to be supplied in the internal cooling flow path of the stationary blade 6 also supplies partly the compressor delivery part fluid of this gas turbine to a seal part between the adjacent stationary blades 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine of a refrigerant recovery type formed to recover a refrigerant (cooling medium) for cooling a gas turbine. The cooling medium is pressurized with a boost compressor to serve as a cooling medium, and this cooling medium is supplied to a refrigerant cavity formed inside the stationary blade to cool the stationary blade from the inside and collect the cooled refrigerant. The present invention relates to a formed refrigerant recovery type gas turbine.

[0002]

2. Description of the Related Art A refrigerant recovery type gas turbine generally employed in the prior art is configured such that fuel is added to a working fluid compressed by a compressor and burned to obtain a high-temperature and high-pressure working fluid to drive the turbine. ing. Typically, the rotational energy of the turbine is converted to electrical energy by a generator coupled to the turbine.

In recent years, great expectations have been placed on improving the efficiency of a combined cycle in which a gas turbine and a steam turbine are combined, and higher working fluid temperatures and higher pressure ratios have been achieved. In addition to this increase in temperature, the development of a closed cooling system that further improves efficiency by effectively utilizing heat energy by recovering the cooling medium in the gas turbine high-temperature section, which has been released into the mainstream gas, is also progressing. In.

[0004] For example, in a gas turbine disclosed in Japanese Patent Application Laid-Open No. 7-189938, air discharged from a gas turbine compressor is pressurized and supplied to a stationary blade, and an outer peripheral end wall, a wing portion, and an inner peripheral end wall are provided. After cooling,
It is collected in a combustor and the combustion air is heated by the heat obtained by cooling the stationary blades.

[0005]

For example, in a high-temperature gas turbine having a working fluid (working gas) temperature of 1400 ° C. or higher, a refrigerant used for cooling a stationary blade having a refrigerant recovery structure is a compressor discharge. There are two types: a refrigerant in which the fluid is cooled and pressurized by a cooler and a boost compressor, respectively, and a refrigerant in which the fluid discharged from the compressor is directly used as the refrigerant.

[0006] The refrigerant obtained by cooling and increasing the pressure of the former compressor discharge fluid by a cooler and a boost compressor, respectively, is used to cool the outer peripheral side and inner peripheral side end walls and wings, and is finally recovered. Is done. On the other hand, the latter, which uses the compressor discharge fluid as it is, is smaller in volume than the former, but uses film cooling for the seal and cooling fluid between the stator vane segments, or for parts with high heat loads. It is used when it is released into the mainstream gas.

Here, these two refrigerants have different pressures and temperatures, and also have different roles in the operation of the gas turbine. Therefore, if they are mixed, the efficiency will be reduced. Also, in the former case where the recovered refrigerant has a cooling capacity, even if a small amount of the refrigerant leaks, the work consumed in the cooler and the boost compressor is lost, and the efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and it is an object of the present invention to efficiently perform closed cooling of an outer peripheral end wall, a wing portion, and an inner peripheral end wall of a stationary blade, and to improve performance and reliability. An object of the present invention is to provide a refrigerant recovery type gas turbine of this type that can be improved.

[0009]

That is, the present invention provides a cooler for extracting and cooling a compressor discharge fluid of a gas turbine as a refrigerant, a boost compressor for increasing the pressure of the cooled refrigerant, and the boosted refrigerant. And a recovery system for recovering the refrigerant discharged from the internal cooling flow path of the vane to the compressor discharge portion of the gas turbine, In a refrigerant recovery type gas turbine configured to supply fluid between adjacent blades and to seal between adjacent stationary blades with the fluid, supply all of the pressurized refrigerant to an internal cooling flow path of the stationary blade. And a seal fluid supply system for supplying a part of the compressor discharge part fluid is provided in the seal portion between the adjacent stator vanes so as to achieve an intended purpose. .

Further, the present invention provides a cooler for extracting and cooling a refrigerant discharged from a compressor of a gas turbine as a refrigerant, a boost compressor for increasing the pressure of the refrigerant cooled by the cooler, and an outer peripheral side for the compressed refrigerant. A supply system that supplies the internal cooling flow path of the stationary blade through the refrigerant cavity of the end wall, and a refrigerant discharged from the internal cooling flow path of the stationary blade through the inner peripheral end wall to a compressor of the gas turbine. A refrigerant recovery type gas turbine, wherein the outer peripheral side end wall is provided so as to supply a fluid between adjacent vanes and seal the fluid between adjacent vanes. And a seal fluid flow passage communicating with the compressor discharge section is provided in the seal section.

In this case, a cooling portion of the inner peripheral side end wall is provided with a merging portion for merging a refrigerant supplied from a plurality of cooling passages formed in the wing portion. A plurality of cooling passages extending from the junction to the inner peripheral end wall frame portion, and a plurality of turbulence promoting ribs are arranged on a cooling surface or a surface facing the cooling surface in the plurality of cooling passages. The inner peripheral side end wall is formed so as to be convectively cooled by the refrigerant flowing from the junction.

Further, the height of the plurality of cooling passages of the inner peripheral side end wall is formed so as to decrease as the position approaches the inner peripheral side end wall frame from the junction. Further, the plurality of cooling passages of the inner peripheral side end wall are formed by a plurality of cooling passage forming ribs and a cooling passage forming cover provided on the inner peripheral side end wall cooling surface. is there.

On the cooling side of the inner peripheral side end wall, an impingement plate having a plurality of small holes is provided with a predetermined gap between the end wall cooling surface and a plurality of impingement plates formed on the wing portion. A converging portion for converging the refrigerant supplied from the cooling flow path is provided, an outlet of the converging portion is provided on the inner peripheral side of the impingement plate, and a part of the refrigerant impinges the inner peripheral end wall. After cooling, the refrigerant after impingement cooling is discharged from the film hole provided in the inner peripheral end wall to the mainstream gas side to cool the film, and a part of the refrigerant is recovered in the combustor. .

That is, in the refrigerant recovery type gas turbine formed as described above, in the gas turbine that performs closed cooling, the outer peripheral end wall of the stationary blade,
The wing portion and the inner peripheral end wall can be efficiently closed-cooled, and the refrigerant can be recovered to the compressor discharge portion, that is, the combustor. Therefore, the wing portion of the stationary blade and the inner and outer peripheral end wall can be efficiently closed-cooled. Thus, performance and reliability can be improved.

In addition, by making the recovered refrigerant cavity a closed type, it is possible to prevent the recovered refrigerant from leaking into the mainstream gas, thereby making it impossible to recover the refrigerant sufficiently, and preventing the overall performance of the gas turbine from deteriorating.

Further, when the refrigerant is recovered by convective cooling of the end wall, the cross-sectional area of the flow passage is adjusted by changing the height of the flow passage in a flow passage shape in which the width of the flow passage is widened structurally. A decrease in the flow rate of the refrigerant can be prevented, and efficient cooling performance can be obtained over the entire end wall. Furthermore, by adjusting the flow path height with a flow path cover,
The same effect as described above can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIG. 1 is a cross-sectional view of a main part of the refrigerant recovery type gas turbine. 1 is a compressor, 2 is a combustor, and 3 is a turbine. Reference numeral 4 denotes a compressor for cooling the air extracted from the discharge portion of the compressor, that is, the compressed air chamber 71, and reference numeral 5 denotes a boost compressor for increasing the pressure of the air from the cooler 4.

The operating principle of the gas turbine constructed as described above will be briefly described. Compressed air discharged from the compressor 1 is guided to a compressed air chamber 71, and a part of the compressed air is supplied to the combustor 2 as combustion air 7a. The supplied and burned air 8 at high temperature and high pressure is sent to the turbine 3 to rotate the turbine blade. The generator uses the rotational energy to generate electricity, but some are also used for compressor drive energy.

On the other hand, a part 7b of the compressed air is
1 and is cooled by the air cooler 4 and pressurized by the boost compressor 5 to become cooling air 9a.
Is supplied to the stationary blade 6 from the outer peripheral side. The supplied cooling air exchanges heat by cooling the stationary vanes 6, and then is collected into the compressed air chamber 71 via the collection system 74 (collected air 9c). At this time, the recovered air 9c is operated to have substantially the same physical property values as the compressor discharge air 7a, that is, the same temperature and the same pressure. A seal air supply system 75 for supplying a part of the compressor discharge section air is provided on the outer peripheral side of the stationary blade 6 at a seal portion between the stationary blade segments. The compressor discharge air 7c is supplied as the cooling air. This air is released into the mainstream gas after use.

FIG. 2 shows a detailed structure of the stationary blade 6, and the cooling of the stationary blade is performed as follows. That is, the cooling air 9 a cooled by the cooler and further boosted by the boost compressor is supplied to the outer peripheral end wall 2 of the stationary blade 6.
The outer peripheral end wall is supplied to the closed mold cavity 21 provided at 0 and is impingement cooled by the impingement plate 22.

After the impingement cooling, the air 9 b cools the wings 23, is guided to the inner peripheral end wall 24, and passes through the convection cooling flow passage 25 provided in the inner peripheral end wall 24 to form the inner peripheral end. The wall 24 is convectively cooled, and is eventually recovered in the compressed air chamber 71 and the combustor (9).
c) is done.

With such a cooling structure,
The outer end wall, the wing portion, and the inner end wall of the stationary blade can be cooled without releasing the cooling air into the mainstream gas, and can be collected in the combustor. Open cooling, which releases cooling air into the mainstream gas as in the past, has a high cooling performance, but has the disadvantage of lowering the mainstream gas temperature raised by the combustor due to the release of cooling air, and for that reason, the The temperature drop had to be borne by the combustion temperature rise. However, when the combustion temperature becomes 1400 ° C. or higher, the increase in the combustion temperature is closely related to the NOx generation amount. Therefore, it is necessary to reduce the decrease in the mainstream gas temperature as much as possible and to suppress the increase in the combustion temperature.

In the stationary blade of the present invention, since the stationary blade including the end wall is closed-cooled, the temperature drop that occurs while the mainstream gas passes through the stationary blade can be reduced. On the other hand, the compressor discharge air 7c, which is a seal and cooling air between the stator blade segments, is supplied to the outside of the cavity 21 as shown in FIG. 3, and therefore is completely mixed with the cooling air 9a. The air is supplied to the space 30 between the segments of the stationary blades without the need for the above.

The role of the compressor discharge air 7c will be described in more detail with reference to FIG. 4. The stator blades are provided with a seal plate groove 31 and a seal plate 2 provided on the side surface of the stator blade.
2 are connected. Here, the compressor discharge air 7c
Flows through the gap 33 between the seal plate 32 and the seal plate groove 31 and leaks into the mainstream gas, albeit in a small amount, to prevent the high-temperature mainstream gas from entering, that is, to seal. At this time, the vicinity of the stator blade seal plate groove, that is, the cooling of the end wall frame portion 34 is also performed.

Further, the cooling air 7c is provided, if necessary,
The convection hole 40 provided in the frame portion 34 allows the frame portion 34
Is cooled by convection, and after cooling, the film is discharged into the mainstream gas to cool the film.

The operating principle of the stationary blade according to the present invention has been described above. However, in the case of closed cooling of the stationary blade, it is necessary to completely separate the cooling air for recovery and the sealing air between the stationary blade segments. . For gas turbine operation, air for sealing between vane segments is indispensable, but apart from the vane inner peripheral side end wall where the temperature and pressure of the recovery cooling air are almost equal to the compressor discharge pressure, especially Substituting the sealing air with the recovered cooling air at the outer peripheral side end wall of the stator vanes releases the cooling air having the cooling capacity obtained by the cooler and the boost compressor, that is, the cooling air having the heat exchange capacity, into the mainstream gas. As a result, the temperature of the mainstream gas is greatly reduced, and the heat recovery is also insufficient. This leads to an immediate decrease in efficiency, thereby impairing the advantage of closed cooling.

In other words, the cooling air for recovery is not allowed to leak into the mainstream gas, even if only a small amount, on the outer peripheral side end wall of the stationary blade. In the gas turbine of the present invention, the closed type cavity for the cooling air for recovery is provided on the end wall on the outer peripheral side of the stationary blade, and is completely separated from the seal air between the stationary blade segments. It is possible to prevent the performance of the gas turbine as a whole from deteriorating without taking advantage of closed cooling due to leakage into gas.

FIG. 5 shows another embodiment of the present invention, in which the outer peripheral side end wall is cooled by convection cooling. The cooling air 9a, which is cooled by the air cooler and further boosted by the boost compressor, is supplied to the cavity 21 provided on the outer peripheral side end wall 20 of the stationary blade 6, and flows through the convection cooling flow path 26a. Convectively cools the outer peripheral side end wall 20, and the air 9 b after the convective cooling cools the wing portion 23, and cools the inner peripheral side end wall 24.
And the convective cooling of the inner peripheral end wall 24 through the convective cooling passage 25 provided in the inner peripheral end wall 24, and the recovered air 9c is recovered by the compressed air chamber 71 and further by the combustor.

In this embodiment, the same effect as that of the embodiment shown in FIGS. 1 to 4 can be obtained, and highly reliable closed cooling can be performed.

FIG. 6 shows still another embodiment. This drawing is a perspective view of the inner peripheral end wall, and a merging portion 51 where a plurality of cooling passages 50 of the wing merge into each other is formed at the wing lower end 23b.
4b, a plurality of cooling passages 25b extending from the confluence portion 51 to the inner peripheral end wall frame portion 35 are formed by a plurality of passage forming ribs 28 and a cover 27, and promote heat transfer to the cooling passages. A plurality of turbulence promoting ribs 29 are arranged.

In the structure thus formed, the cooling air 9b that has cooled the wings joins at the junction 51 at the lower end of the wing, and flows into the plurality of flow paths 25b that extend from the junction 51 to the end wall frame 35. Flows from the confluence portion 51 toward the end wall frame portion 35 to convectively cool the inner peripheral end wall. The cooled air 9c is recovered from the gap 70 formed between the end wall frame 35 and the cover 27, and is finally supplied again to the combustor. With such a structure, the inner peripheral end wall can be easily cooled with the air having cooled the wings, and the cooling air can be easily collected.

FIG. 7 shows a modification of the embodiment shown in FIG. FIG. 7 is a sectional view of the inner peripheral side end wall convection cooling passage 25b. When forming the plurality of convection cooling passages 25b shown in FIG. 6, since the peripheral length of the blade lower end portion 23b and the peripheral length of the end wall frame portion 35 are longer, the peripheral length of the end wall frame portion is longer. The width of the convection cooling channel must be formed so as to increase from the wing portion to the end wall frame portion. Therefore, when the height of the cooling flow path is the same, the flow path cross-sectional area increases from the wing portion to the end wall frame portion, and the flow velocity of the cooling air decreases. The temperature of the cooling air rises from the wings to the picture frame due to heat exchange for cooling. In other words, the closer to the frame, the lower the cooling effect, and it may not be possible to obtain efficient cooling.

Therefore, as shown in FIG. 7, the cover 27 reduces the flow path height 60 toward the picture frame, that is, the cross-sectional area of the cooling flow path is manipulated, and the cooling air near the picture frame is reduced. By preventing the flow velocity from decreasing, it is possible to obtain a uniform cooling effect in the flow path.

FIG. 8 shows a modification of the embodiment shown in FIG. FIG. 8 is a cross-sectional view of the inner peripheral side end wall convection cooling passage 25b, in which the turbulent flow promoting ribs 29 are arranged only on the cover 27 side. The cooling mechanism is the same as that shown in FIGS. Generally, the turbulence-promoting ribs provided on the cooling surface provide a higher heat transfer promoting effect.However, even if they are provided on the opposite surface on the opposite side, the performance slightly decreases, but the effect of promoting heat transfer on the cooling surface Confirmed in experiments.

That is, in the model experiment, one side is 10 mm,
The other side has a rectangular flow path of 1.5 mm, and one of the two surfaces opposed to the long side of 10 mm is regarded as a non-heated surface. The experiment was conducted using the other smooth surface as an overheating surface and using air as a cooling medium.

FIG. 9 is a characteristic diagram showing the results of the experiment. In FIG. 9, the horizontal axis represents the dimensionless Reynolds number Re representing the flow state of the cooling medium, and the vertical axis represents the dimensionless Nusselt number Nu representing the heat transfer characteristics.

[0037]

(Equation 1)

D: equivalent diameter of cooling medium flow path, v: cooling medium flow rate, α: heat transfer coefficient, ν: kinematic viscosity coefficient of cooling medium, λ: thermal conductivity of cooling medium, on the surface facing the cooling surface Even when the turbulence promoter was provided, the heat transfer characteristic was approximately 1.8 times that of the smooth channel. In the case where the turbulence promoting member is provided on the cooling surface, the heat transfer characteristic is about 4.4 times that of the smooth flow path. Therefore, in the example of the present invention, the turbulence promoting rib 29 is provided only on the cover 27 side where processing is easier, and the turbulent flow promoting effect is smaller than that in FIG. 7 in which the turbulent flow promoting rib is arranged on the cooling surface. Although somewhat inferior, when the turbulence promoting ribs cannot be arranged on the cooling surface due to processing restrictions, the cooling effect can also be obtained by this method.

FIG. 10 shows a further modification of the present invention, and shows a cooling structure for the inner peripheral side end wall of the stationary blade. The recovery cooling air 9b after the blade cooling does not have a cooling capacity capable of performing closed convection cooling of the inner peripheral end wall 24. At this time, the temperature and pressure of the recovery cooling air after the blade cooling are changed to the compressor discharge. When the air has reached the same level as the air, the wing cooling air merger outlet 5
2 is provided on the inner peripheral side of the impingement plate 53, the inner peripheral end wall 24 is impingement-cooled with a part of the recovered air 9b, and the air after the impingement cooling is applied to the film holes provided on the inner peripheral end wall 24. The film is released into the mainstream gas by 43 and the inner peripheral end wall surface is film-cooled.

The remaining cooling air 9c is collected at the combustor inlet. In this case, even if the cooling air used for the inner peripheral side end wall cooling is a part of the recovery cooling air, the cooling capacity is equivalent to that of the compressor discharge air, and even if a part of the cooling air is discharged, the gas turbine is cooled. There is no significant loss in performance.

As described above, according to the turbine formed as described above, in the refrigerant recovery type gas turbine, that is, in the gas turbine that performs closed cooling, the outer peripheral end wall, the wing portion, and the inner peripheral surface of the stationary blade are provided. Closed cooling of the side end wall can be efficiently performed, and the outer end wall, which is the cooling medium supply side of the stationary blade, has a closed cavity for supplying the recovery medium, and is completely separated from the sealing air between the stationary blade segments. For this reason, it is possible to prevent the recovery medium from leaking into the mainstream gas and to reduce the overall performance of the gas turbine, thereby improving reliability.

Although the above embodiment has been described with reference to the case where the cooling medium is air, it is needless to say that the cooling medium can be applied to various cooling media such as steam and nitrogen irrespective of air. is there.

[0043]

As described above, according to the present invention, the refrigerant capable of efficiently performing closed cooling of the outer peripheral end wall, the wing portion, and the inner peripheral end wall of the stationary blade, and improving performance and reliability. A recovery type gas turbine can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing one embodiment of a refrigerant recovery type gas turbine of the present invention.

FIG. 2 is an enlarged sectional view showing a wing portion of FIG. 1;

FIG. 3 is a perspective view of FIG. 2;

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a sectional view of a main part showing another embodiment of the present invention.

FIG. 6 is a perspective view of a main part showing another embodiment of the present invention.

FIG. 7 is a sectional view of a main part showing a modification of the present invention.

FIG. 8 is a sectional view of a main part showing a modification of the present invention.

FIG. 9 is a characteristic diagram showing a result of a heat transfer model experiment.

FIG. 10 is a sectional view of a main part showing a modification of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... gas path after a compressor, 2 ... combustor, 3 ... gas path of turbine part, 4 ... air cooler, 5 ... boost compressor, 6
... First stage stationary blades, 7a, 7b ... Compressor discharge air, 7c ... Seal air between stationary blade segments, 8 ... High temperature and high pressure air, 9a,
9b, 9c: recovery cooling air, 20: stationary blade outer peripheral side end wall, 21: recovery air cavity, 22: impingement plate, 23: blade, 23a: blade lower end, 24 ...
Inner peripheral end wall, 25, 25b convection cooling flow path,
26: convection cooling channel, 27: convection cooling channel forming cover,
28: convection cooling channel forming rib, 29: turbulence promoting rib, 3
0: between stator blade segments, 31: stator blade side seal plate groove, 32: seal plate, 33: seal gap, 3
4 ... stationary blade outer peripheral side end wall frame, 35 ... stationary blade inner peripheral side end wall frame, 40 ... convection cooling hole, 43 ... film cooling hole, 50 ... blade cooling passage, 51 ... cooling air junction, 52: cooling air junction outlet, 53: impingement plate, 60: convection cooling channel height, 70: cooling air recovery gap, 71: compressed air chamber, 72: casing, 73 ...
Supply system, 74: recovery system, 75: seal fluid supply system.

Claims (7)

[Claims] 1. A compressor for extracting and cooling a compressor discharge fluid of a gas turbine as a refrigerant, a boost compressor for increasing the pressure of the cooled refrigerant, and supplying the increased pressure refrigerant to an internal cooling passage of a stationary blade. A supply system for supplying the fluid, and a recovery system for recovering the refrigerant discharged from the internal cooling flow passage of the vane to a compressor discharge part of the gas turbine, and supplying a fluid between adjacent vanes. A refrigerant recovery type gas turbine formed to seal between adjacent stationary blades, wherein all of the pressurized refrigerant is formed to be supplied to an internal cooling flow path of the stationary blade, and A refrigerant recovery type gas turbine, wherein a seal fluid supply system that supplies a part of the compressor discharge section fluid is provided in the blade-to-blade seal section. 2. A cooler for extracting and cooling a refrigerant discharged from a compressor of a gas turbine as a refrigerant, a boost compressor for increasing the pressure of the refrigerant cooled by the cooler, and a booster for compressing the increased pressure of the refrigerant. A supply system for supplying the internal cooling passage of the stationary blade via the refrigerant cavity, and a refrigerant discharged from the internal cooling passage of the stationary blade via the inner peripheral side end wall to a compressor discharge portion of the gas turbine. A refrigerant recovery type gas turbine, wherein the refrigerant recovery type gas turbine is configured to supply a fluid between adjacent vanes and to perform a seal between the adjacent vanes by the fluid. A refrigerant recovery type gas turbine, wherein a seal fluid flow passage communicating with the compressor discharge portion is provided in the seal portion. 3. A cooling side of the inner peripheral end wall,
A plurality of cooling flows that are provided on the inner peripheral side end wall cooling surface and that extend from the converging portion to the inner peripheral side end wall frame portion; A passage is provided, and a plurality of turbulence promoting ribs are arranged on a cooling surface in the plurality of cooling passages, and the turbulence promoting ribs are formed so as to convectively cool the inner peripheral side end wall by the circulating refrigerant from the junction. 3. The refrigerant recovery type gas turbine according to 2. 4. A cooling side of the inner peripheral end wall,
A cooling portion provided with a plurality of cooling flows that are supplied from a plurality of cooling passages formed in the wing portion; and a plurality of cooling flows extending from the joining portion to the inner peripheral end wall frame on the inner peripheral end wall cooling surface. A path is provided, and a turbulence promoting rib is arranged on a surface of the plurality of cooling passages facing the cooling surface, and after supplying a refrigerant from a junction to convectively cool the inner peripheral end wall, the refrigerant is cooled. 3. A refrigerant recovery type gas turbine according to claim 2, wherein the refrigerant is recovered in a combustor. 5. A flow path height of the plurality of cooling flow paths of the inner peripheral side end wall is formed so as to decrease as approaching from the junction to the inner peripheral side end wall frame. Or the refrigerant recovery type gas turbine according to 4. 6. A plurality of cooling passages of the inner peripheral end wall are formed by a plurality of cooling passage forming ribs provided on the inner peripheral end wall cooling surface and a cooling passage forming cover. The refrigerant recovery type gas turbine according to claim 3. 7. An impingement plate having a plurality of small holes with a predetermined gap between the inner peripheral side end wall and a cooling surface of the end wall is provided on a cooling side of the inner peripheral side end wall. A converging portion for converging the refrigerant supplied from the cooling flow path is provided, an outlet of the converging portion is provided on the inner peripheral side of the impingement plate, and a part of the refrigerant impinges the inner peripheral end wall. Cool down,
5. The cooling method according to claim 3, wherein the refrigerant after the impingement cooling is discharged to a mainstream gas side from a film hole provided in an inner peripheral end wall to cool the film and a part of the refrigerant is recovered to a combustor. Refrigerant recovery type gas turbine.