JPH10331608A - Closed steam cooling gas turbine combined plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make cooling steam serve as superheated steam and prevent generation of rotor vibration resulting from water being mixed in rotor blade cooling steam by supplying a part of steam from a high-pressure turbine to a cooling flow passage formed at turbine, and combining the steam passing through the cooling flow passage with the steam from a reheater. SOLUTION: This turbine combined plant supplies exhaust gas from a turbine 3 which forms a gas turbine device together with a compressor 1 and a combustor 2 to a exhaust heat recovery boiler 9 through a route 8, whereas a branch point 43 is formed on the way of the piping for steam from a high-pressure steam turbine 4, the steam branched at this point is guided to a combined point 49 through piping 48, and the outlet steam of a medium pressure superheater 18 in the exhaust heat recovery boiler 9 is made to join. The combined steam is supplied to the stationary blade 51 and the moving blade 52 of the turbine 3 from a branching point 50 as cooling steam. The steam after cooling is recovered at a combined point 53, combined with the steam from a secondary reheater 23 at a combined point 54, passes through a stop valve 33, and supplied to a medium pressure steam turbine 5 for intended work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an operation control method for a closed steam-cooled gas turbine combined plant.

[0002]

2. Description of the Related Art An operation control method for a closed steam-cooled gas turbine combined plant is disclosed in Japanese Patent Application Laid-Open No. H4-148035, in which the gas turbine is not cooled with steam at the time of startup or emergency, but with air from a compressor. And JP-A-4-242987. Also, 95Us-442583
Also describes the general operation method.

[0003]

The most efficient cooling steam supply and recovery system in a closed steam-cooled gas turbine combined plant having a reheat triple pressure bottoming cycle is a part of the steam at the outlet of the high-pressure steam turbine. This system cools the high-temperature part and collects the cooled steam at the inlet of the medium-pressure steam turbine. The present invention aims to solve the problem for this system.

[0004] In order to keep the metal temperature in the high temperature portion of the gas turbine low and to reduce the amount of cooling steam, it is necessary to lower the cooling steam temperature. However, when the cooling steam temperature is lowered while securing the cooling steam pressure, the temperature approaches the saturation temperature, and the possibility that the steam contains moisture may appear. Since the moving blade rotates at high speed and receives a centrifugal force, if water is mixed into the moving blade cooling steam, an imbalance in mass occurs, which may cause rotor vibration. Therefore, it is necessary to avoid using saturated steam which may cause drainage as the blade cooling steam. It is preferable to avoid using superheated steam with water or saturated steam to cool the rotor blades because steam may contain moisture.

[0005] The cooling steam must be at a higher pressure than the mainstream gas. If the mainstream gas is at a higher pressure than the cooling steam, the gas will enter the cooling steam from a slight gap in the cooling section. When gas is mixed into the cooling steam, the oxygen concentration in the steam increases, which causes corrosion of the steam turbine and the exhaust heat recovery boiler. Particularly when the gas turbine has a low load, the main stream gas may have a higher pressure than the cooling steam because the steam pressure generated in the exhaust heat recovery boiler is low.

When the steam generated by the exhaust heat recovery boiler is not guided to the steam turbine but is bypassed to the condenser at the time of low load on the gas turbine, the cooling steam is not supplied from the high-pressure steam turbine outlet. .
If no cooling steam is supplied to the gas turbine hot section, the gas will flow back into the cooling steam passage. Also, if the amount of cooling steam decreases because the cooling steam is not supplied from the high-pressure steam turbine outlet, the temperature of the cooling steam recovered from the gas turbine increases, and the temperature difference between the supplied steam and the recovered steam increases, causing The acting thermal stress can be excessive.

[0007]

SUMMARY OF THE INVENTION A steam-cooled gas turbine combined plant according to the present invention comprises a compressor for compressing air, a combustor for burning air and fuel compressed by the compressor, and a flue gas discharged from the combustor. A gas turbine including a turbine driven by a gas turbine, and an exhaust heat recovery boiler that generates steam using exhaust gas discharged from the gas turbine as a heat source,
A steam turbine driven by steam generated by the exhaust heat recovery boiler, wherein the steam turbine is supplied with steam generated by the exhaust heat recovery boiler;
A reheater provided in the exhaust heat recovery boiler for reheating steam from the high-pressure steam turbine, a medium-pressure turbine for supplying the reheated steam, and a supply of steam from the medium-pressure turbine In a gas turbine combined plant including a low-pressure turbine, the turbine includes a cooling passage, and a part of steam exiting from the high-pressure turbine is supplied to the cooling passage of the turbine and passes through the cooling passage of the turbine. Steam is configured to merge with the steam exiting the reheater. Then, the steam discharged from the reheater and the steam after cooling the turbine are merged and supplied to the medium-pressure turbine.

Further, the steam discharged from the high-pressure turbine is mixed with superheated steam generated from the exhaust heat recovery boiler at a lower temperature than the steam discharged from the high-pressure turbine, and then supplied to a cooling passage in the turbine. It is configured to be.

Further, the exhaust heat recovery boiler includes a steam generator for generating low-pressure, medium-pressure, and high-pressure steam, and the steam generators are respectively supplied from a conserving unit to which water is supplied and from a conserving unit. An evaporator to which supply water is supplied, and a superheater to which steam from the evaporator is supplied, wherein steam from the high-pressure turbine exits from a superheater provided in the medium-pressure steam generator section. After being mixed with the steam, it is configured to be supplied to a cooling passage in the turbine.

[0010] Further, the exhaust heat recovery boiler is provided with a medium pressure superheater,
A part or all of the intermediate-pressure superheated steam generated by the intermediate-pressure superheater is mixed with high-pressure steam turbine outlet steam for cooling a high-temperature portion of the gas turbine.

Further, the exhaust heat recovery boiler is provided with a medium pressure superheater,
A part or all of the intermediate-pressure superheated steam generated by the intermediate-pressure superheater is mixed with the high-pressure steam turbine outlet steam for cooling the high-temperature portion of the gas turbine, and the exhaust heat recovery boiler is used during the rated operation. The temperature of the intermediate-pressure superheated steam generated by the pressure superheater is set lower than the high-pressure steam turbine outlet steam temperature to cool a high-temperature portion of the gas turbine.

Further, a pipe for supplying superheated steam after cooling the high-temperature portion of the gas turbine and recovering the superheated steam and reheated by the reheater of the exhaust heat recovery boiler to the superheated steam to the medium pressure steam turbine. In addition, a valve for controlling the pressure of steam for cooling the high temperature portion of the gas turbine is provided.

A pipe for supplying the superheated steam after cooling the high-temperature portion of the gas turbine and mixing the superheated steam recovered by the reheater of the exhaust heat recovery boiler with the superheated steam to the intermediate-pressure steam turbine. A valve for controlling the pressure of steam for cooling the high-temperature portion of the gas turbine is provided above, and at least the outlet air pressure of the compressor is used as a control variable of the valve.

Further, a pipe for supplying the superheated steam after cooling the high temperature portion of the gas turbine and mixing the superheated steam recovered by the reheater of the exhaust heat recovery boiler to the intermediate pressure steam turbine. A valve for controlling the pressure of steam for cooling the high-temperature portion of the gas turbine is provided above, and an inlet pressure of the valve and an outlet air pressure of the compressor are used as control variables of the valve.

Further, a pipe for supplying the superheated steam after cooling the high temperature portion of the gas turbine and mixing the superheated steam recovered by the reheater of the exhaust heat recovery boiler to the intermediate pressure steam turbine. On top, a valve is installed to control the pressure of the steam that cools the gas turbine hot section, and as the control variables for the valve, the compressor outlet air pressure and the high pressure steam turbine outlet or the medium pressure superheater outlet are connected to the gas turbine hot section. It is characterized by using the pressure of steam during the process.

A pipe for supplying the superheated steam after cooling the high-temperature portion of the gas turbine and mixing the superheated steam recovered by the reheater of the exhaust heat recovery boiler to the intermediate-pressure steam turbine. On top, a valve is installed to control the pressure of the steam that cools the high-temperature section of the gas turbine. Is used.

Further, a stop valve is provided at the inlet of the high-pressure steam turbine, and a first pipe on which steam before the stop valve flows to the condenser while bypassing the high-pressure steam turbine, a first valve on the pipe, and a discharge pipe. A second pipe connecting any position from the high pressure evaporator outlet of the heat recovery boiler to just before the first pipe with a cooling steam supply pipe in the gas turbine high temperature section and high pressure steam flowing to the gas turbine high temperature section; And the second valve above. Further, when the stop valve is closed, the first valve and the second valve are both opened, and when the stop valve is open, both the first valve and the second valve are closed. Features.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

The gas turbine device comprises a compressor 1, a combustor 2, and a turbine 3. The steam turbine device comprises a high-pressure steam turbine 4, a medium-pressure steam turbine 5, and a low-pressure steam turbine 6, and a generator 7 and a gas turbine. The turbine device and the steam turbine device are installed coaxially.

From the turbine 3, a path 8 is connected to an exhaust heat recovery boiler 9. Exhaust heat recovery boiler 9 has low pressure economizer 1
0, low pressure drum 11, low pressure evaporator 12, medium pressure economizer 1
3, medium pressure drum 14, medium pressure evaporator 15, low pressure superheater 1
6, High pressure economizer 17, Medium pressure super heater 18, High pressure drum 1
9, high pressure evaporator 20, high pressure primary superheater 21, primary reheater 22, secondary reheater 23, high pressure secondary superheater 24, feed water pump 25, medium pressure pump 26, high pressure pump 27, recirculation A pump 28 is provided.

The exhaust heat recovery boiler 9 is provided with a steam generating section for generating high-pressure, medium-pressure and low-pressure steam.

The steam turbine system includes a high-pressure steam turbine 4,
It comprises a medium-pressure steam turbine 5, a low-pressure turbine 6, and a condenser 29. At the inlet of the high-pressure steam turbine 4, a stop valve 30 and a bypass pipe 31 connected to the condenser 29 from the inlet of the stop valve 30 and a bypass valve 32 on the bypass pipe 31.
Is installed. At the inlet of the intermediate-pressure steam turbine 5, a stop valve 33 and a bypass pipe 34 connected to the condenser 29 from the inlet of the stop valve 33 and a bypass valve 35 on the bypass pipe 34 are installed. At the inlet of the low-pressure steam turbine 6, a stop valve 36 and a bypass pipe 37 connected to the condenser 29 from before the inlet of the stop valve 36 and a bypass valve 38 on the bypass pipe 37 are provided.

The compressor inlet air 39 is pressurized by the compressor 1 and supplied to the combustor 2. The air supplied to the combustor 2 reacts with the fuel 40 and the high-temperature combustion gas is supplied to the turbine 3. The combustion gas that has passed through the turbine 3 becomes exhaust gas and is supplied to an exhaust heat recovery boiler 9 through a path 8. The exhaust gas recovered by the heat recovery boiler 9 is released to the atmosphere.

The water supplied from the condenser 29 is supplied to the water supply pump 25.
And flows into the low pressure economizer 10 in the exhaust heat recovery boiler 9. The outlet feedwater of the low-pressure economizer 10 is supplied to the low-pressure drum 11 and at the same time, the medium-pressure pump 26 and the recirculation pump 28
Supplied to The water supply at the outlet of the recirculation pump 28 joins the low-pressure economizer 10 inlet to raise the low-pressure economizer inlet feedwater temperature to prevent low-temperature corrosion of the low-pressure economizer 10 due to condensation.
The water supply at the outlet of the medium pressure pump 26 is guided to the medium pressure economizer 13 and supplied to the medium pressure drum 14 and the high pressure pump 27. The water supply at the outlet of the high-pressure pump 27 is supplied to the high-pressure drum 19 through the high-pressure economizer 17. The feed water of the high-pressure drum 19 becomes saturated steam in the high-pressure evaporator 20 and is supplied to the high-pressure primary superheater 21. The steam exiting the high-pressure primary superheater 21 is supplied to the high-pressure secondary superheater 2
4 is supplied. From the gas turbine rated operation to a predetermined low load, the stop valve 30 is opened and the bypass valve 32 is opened.
Is closed, and the high-pressure secondary superheater 24 outlet steam is supplied to the high-pressure steam turbine 4 through the main steam pipe 41. The steam that has worked in the high-pressure steam turbine 4 reaches the branch point 43 through the pipe 42, and a part of the steam is supplied to the primary reheater 22 through the pipe 45 and the throttle 44 on the pipe 45. The steam exiting the primary reheater 22 is supplied to a secondary reheater 23. From the gas turbine rated operation to a predetermined low load, the stop valve 33 is open and the bypass valve 35 is closed, and the steam exiting the secondary reheater 23 is supplied to the medium-pressure steam turbine 5 through the pipe 46. Is done. The steam that has worked in the medium-pressure steam turbine 5 is supplied to the low-pressure steam turbine 6 inlet through a pipe 55. On the other hand, the water supplied to the low-pressure drum 11 is evaporated by the low-pressure evaporator 12 and guided to the low-pressure superheater 16. From the gas turbine rated operation to a predetermined low load, the stop valve 36 is open, the bypass valve 38 is closed, and the low-pressure superheater 1 is closed.
The steam that has exited 6 passes through a pipe 47 and merges with the steam from the outlet of the medium-pressure steam turbine at the inlet of the low-pressure steam turbine 6 and is supplied to the low-pressure steam turbine 6. The steam that has exited the low-pressure turbine 6 becomes water in the condenser 29, and is supplied to the exhaust heat recovery boiler 9 by the water supply pump 25.

The cooling system of the gas turbine will be described. The steam that has passed through the pipe 48 from the branch point 43 is
Reach At the junction 49, it merges with the intermediate-pressure superheater outlet steam. The steam from the junction 49 reaches the branch point 50. From the branch point 50, the cooling steam is supplied to the stationary blade 51 and the moving blade 52,
The cooled steam is recovered from the stationary blades 51 and the moving blades 52 and reaches a junction 53. The steam that has reached the confluence point 53 is
At 4, the steam merges with the steam exiting the secondary reheater 23, passes through the stop valve 33, and is supplied to the medium-pressure steam turbine 5.
The amount of cooling steam supplied from the outlet of the high-pressure steam turbine 4 is set by a throttle 44 provided on a pipe 45 extending from the branch point 43 to the primary reheater 22. FIG. 2 shows the gas turbine load, the high-pressure steam turbine outlet steam, the medium-pressure superheater outlet steam, and the supply when the intermediate-pressure superheater outlet steam temperature is set to be lower than the high-pressure steam turbine outlet steam temperature at the rated point. The relationship of the side cooling steam temperature is shown. The gas turbine exhaust gas temperature at which the efficiency is maximized as a combined plant is about 600 ° C. at the rated point. When the gas turbine exhaust gas temperature is about 600 ° C., the conditions of the steam generated from the exhaust heat recovery boiler are 566 ° C. and 165 atm for the high pressure steam and 566 ° C. and 35 atm for the reheated steam. It is about 45ata.

The saturated steam pressure of 45ata is about 255 ° C., and if the outlet pressure of the medium pressure superheater is set to 280 ° C. at the rated point, the cooling steam temperature on the supply side becomes about 350 ° C. From this figure, since the outlet steam of the high-pressure steam turbine is cooled by mixing with the outlet steam of the intermediate-pressure superheater, the supply-side cooling steam is 30 ° C. lower than the outlet steam of the high-pressure steam turbine. By lowering the supply side cooling steam temperature, cooling can be performed with a small amount of cooling steam, which leads to an improvement in efficiency. Since the outlet steam of the high-pressure steam turbine 4 is always operated as superheated steam and the outlet steam of the intermediate-pressure superheater is also always superheated steam, the mixed steam of the outlet steam of the high-pressure steam turbine 4 and the intermediate-pressure superheater outlet steam is used. Is also superheated steam. Therefore, the possibility that moisture is mixed into the moving blade cooling steam is reduced, and the reliability is improved. Further, by combining the steam at the outlet of the high-pressure steam turbine with the steam at the outlet of the intermediate-pressure superheater, the temperature difference at the junction is smaller than in the case of mixing the steam with the medium-pressure saturated steam, leading to a reduction in the thermal stress of the piping.

FIG. 3 shows another embodiment of the present invention. This embodiment differs from the embodiment of FIG. 1 in that a pressure control valve 56 is provided on a pipe connecting a junction 54 and a turbine bypass branch point 57. FIG. 4 shows the relationship between the pressure of the cooling steam at the branch point 50 and the air pressure at the outlet of the compressor 1 when the pressure control valve 56 is not installed and when it is installed. Pressure control valve 5
When the gas turbine 6 is not installed, the steam pressure generated in the exhaust heat recovery boiler 9 decreases because the gas turbine exhaust gas temperature decreases as the gas turbine load decreases. As the steam pressure generated by the exhaust heat recovery boiler 9 decreases, the outlet pressure of the high-pressure steam turbine, that is, the cooling steam pressure also decreases. At the rated point, the supply steam pressure is 45ata, but the pressure drops to about 5ata at no load. On the other hand, the air pressure at the outlet of the compressor 1 also decreases as the load on the gas turbine decreases.
Since the cooling rate is smaller than that of the cooling steam, the pressure reversal occurs at a gas turbine load of about 25% (point A). This pressure reversal induces the mainstream gas to have a higher pressure than the cooling steam, and the gas enters the cooling steam from a slight gap in the cooling section. When gas is mixed into the cooling steam, the oxygen concentration in the steam increases, which causes corrosion of the steam turbine and the exhaust heat recovery boiler. By installing the pressure control valve 56 and performing pressure control by the pressure control valve 56 at a gas turbine load of about 45% or less (point B), the cooling steam pressure can be increased. It is possible to prevent the reversal of the air pressure, that is, the mainstream gas from being at a higher pressure than the cooling steam.

FIG. 5 shows another embodiment of the present invention. This embodiment is different from the embodiment of FIG. 3 in that the control variables of the pressure control valve 56 are the compressor 1 outlet air pressure 61 and the pressure control valve 5.
6 in that a steam pressure of 60 at the inlet is used. Here, the compressor 1 outlet air pressure 61 is a pressure at an arbitrary position from the compressor outlet to the combustion air taken into the combustor 2 as combustion air. The compressor 1 outlet air pressure 61 and the pressure control valve 56 inlet steam pressure 60 are taken into the controller 62, and the signal from the controller 62 controls the pressure control valve 56. Details of the controller 62 are shown in FIG. The signal Pc of the compressor 1 outlet air pressure 61 is input to a calculator a in the controller 62. The computing unit a calculates the pressure on the mainstream gas side of the part to be cooled from the air pressure at the outlet of the compressor 1 and calculates the mainstream gas side pressure signal P of the part to be cooled.
c 'is output. The signal Ps of the steam pressure 60 at the inlet of the pressure control valve 56 is input to a calculator b in the controller 62. The computing unit b calculates the pressure of the cooling steam of the portion to be cooled from the steam pressure at the inlet of the pressure control valve 56, and outputs a cooling steam pressure signal P of the portion to be cooled.
Output s'. Ps'-Pc 'passed through the subtractor 63
Is input to the calculator c. When Ps'-Pc 'is a positive value, it indicates that the cooling steam is higher in the cooled portion than in the mainstream gas side, and when Ps'-Pc' is a negative value, the cooling steam is The pressure is lower than that of the mainstream gas. The computing unit c outputs the opening signal Vc of the pressure control valve 56 so that Ps'-Pc 'matches a preset target value. When Ps'-Pc 'is smaller than the target value, the valve opening of the pressure control valve 56 is reduced to increase the pressure of the cooling steam, and when Ps'-Pc' is larger than the target value, the pressure control valve 56 is increased. The controller 62 operates so as to increase the valve opening degree and decrease the pressure of the cooling steam.

FIG. 7 shows another embodiment of the present invention. This embodiment differs from the embodiment of FIG. 5 in that only the air pressure 61 at the outlet of the compressor 1 is used as a control variable of the pressure control valve 56. In this embodiment, the compressor 1 outlet air pressure 61
From this, the pressure of the cooling steam and the mainstream gas in the portion to be cooled is calculated.

FIG. 8 shows another embodiment of the present invention. This embodiment is different from the embodiment of FIG. 5 in that the control variable of the pressure control valve 56 is not the steam pressure at the inlet of the pressure control valve 56 but the supply-side cooling steam pressure 64 after the junction 49. . In the present embodiment, the pressure of the cooling steam in the portion to be cooled is calculated from the supply-side cooling steam pressure 64.

FIG. 9 shows another embodiment of the present invention. This embodiment differs from the embodiment in FIG. 5 in that the control variable of the pressure control valve 56 is not the inlet steam pressure of the pressure control valve 56 but the recovery side cooling steam pressure 65 before the junction 54. . In the present embodiment, the pressure of the cooling steam in the portion to be cooled is calculated from the pressure 65 of the cooling steam on the recovery side.

FIG. 10 shows another embodiment of the present invention. This embodiment is different from the embodiment in FIG. 1 in that a medium-pressure superheater, which is a cooling steam supply pipe, is provided from a pipe 41 located between an outlet of the high-pressure evaporator 20 and a branch point 72 just before an inlet of the high-pressure steam turbine 4. The point is that a pipe 71 connecting the outlet pipe 73 and a valve 70 on the pipe 71 are provided. The turbine bypass operation may be performed when the gas turbine is under a low load or in an emergency. In the turbine bypass operation, the stop valves 30, 33, and 36 are closed and the bypass valves 32, 35, and 38 are opened, and the steam reaching the steam turbine inlet does not flow into the steam turbines 4, 5, and 6, and the pipes 31, 34 are not used. , 37 through condenser 2
Flow into 9 Therefore, in the turbine bypass operation, no cooling steam is supplied from the outlet of the high-pressure steam turbine 4, and cooling is performed only by the steam from the intermediate-pressure superheater 18, resulting in a shortage of cooling steam. When the cooling steam is insufficient, the stationary blade 51 and the moving blade 5
2 cannot be suppressed below the allowable temperature,
The temperature of the recovered steam increases, and the temperature difference between the supplied steam and the recovered steam in the rotor increases, which may cause a problem of thermal stress. Therefore, at the time of the turbine bypass operation, the valve 70 is opened, and the high-pressure secondary superheater outlet steam is also supplied as the cooling steam, so that the cooling steam amount can be secured.

[0033]

As described above, according to the present invention,
A medium-pressure superheater is provided in the exhaust heat recovery boiler, and a part or all of the medium-pressure superheated steam generated by the medium-pressure superheater is mixed with high-pressure steam turbine outlet steam for cooling a high-temperature portion of the gas turbine. As a result, the cooling steam becomes superheated steam,
Moisture is mixed into the moving blade cooling steam to cause an imbalance in mass, which eliminates the possibility of causing rotor vibration and improves reliability.

According to the present invention, the exhaust heat recovery boiler is provided with a medium-pressure superheater, and the medium-pressure superheated steam generated by the medium-pressure superheater is added to the high-pressure steam turbine outlet steam for cooling the high-temperature portion of the gas turbine. Part or all of the gas turbine, and the temperature of the medium-pressure superheated steam generated by the medium-pressure superheater of the exhaust heat recovery boiler during the rated operation is set to a temperature lower than the high-pressure steam turbine outlet steam temperature. By cooling the cooling water, the temperature of the cooling steam can be lowered, and the amount of the cooling steam decreases, and the plant efficiency improves.

According to the present invention, the superheated steam after cooling the high-temperature portion of the gas turbine and recovered is mixed with the superheated steam reheated by the reheater of the exhaust heat recovery boiler, and the superheated steam is mixed into the medium-pressure steam turbine. By installing a valve on the supply pipe to control the pressure of the steam that cools the high-temperature section of the gas turbine, the pressure of the cooling steam can be constantly maintained at a higher pressure than the mainstream gas pressure. Since backflow can be prevented, corrosion of the steam turbine and the exhaust heat recovery boiler can be suppressed.

According to the present invention, a stop valve is provided at the inlet of the high-pressure steam turbine, and the first pipe on which steam before the stop valve flows to the condenser while avoiding the high-pressure steam turbine and flows to the condenser. A second valve is connected to any position from the high-pressure evaporator outlet of the exhaust heat recovery boiler to just before the first pipe and the cooling steam supply pipe of the gas turbine high-temperature section, and the high-pressure steam flows to the gas turbine high-temperature section. By providing the pipe and the second valve on the pipe, the mixed steam of the steam and the high-pressure steam from the intermediate pressure superheater outlet can be used as the cooling steam during the turbine bypass operation, so that the cooling steam amount is secured. The temperature rise of the cooling steam recovered from the gas turbine can be suppressed, and the temperature difference between the supply steam and the recovered steam can be reduced, so that an increase in thermal stress acting on the rotor can be prevented.

[Brief description of the drawings]

FIG. 1 is a system diagram of a closed steam-cooled gas turbine combined plant according to an embodiment of the present invention.

FIG. 2 is a cooling steam temperature diagram according to an embodiment of the present invention.

FIG. 3 is a system diagram of a closed steam-cooled gas turbine combined plant according to an embodiment of the present invention.

FIG. 4 is a pressure diagram of supply-side cooling steam and compressor outlet air according to an embodiment of the present invention.

FIG. 5 is a system diagram of a closed steam-cooled gas turbine combined plant according to an embodiment of the present invention.

FIG. 6 is a valve control diagram according to an embodiment of the present invention.

FIG. 7 is a system diagram of a closed steam-cooled gas turbine combined plant according to an embodiment of the present invention.

FIG. 8 is a system diagram of a closed steam-cooled gas turbine combined plant according to an embodiment of the present invention.

FIG. 9 is a system diagram of a closed steam-cooled gas turbine combined plant according to an embodiment of the present invention.

FIG. 10 is a system diagram of a closed steam-cooled gas turbine combined plant according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Compressor, 2 ... Combustor, 3 ... Turbine, 4 ... High pressure steam turbine, 5 ... Medium pressure steam turbine, 51 ... Stator vane, 52 ...
Moving blades, 56: pressure control valve, 60: pressure steam at inlet of pressure control valve, 61: air pressure at compressor outlet, 62: controller, 64 ...
Supply side cooling steam pressure, 65 ... collection side cooling steam pressure, 70
... Valve, 71 ... Piping.

Claims (10)

[Claims] An air and a fuel compressed by a compressor are burned in a combustor, and a combustion gas is used to drive a turbine. An exhaust heat recovery boiler having a steam generator for generating steam of three types of pressures of medium pressure and low pressure; and a high-pressure, medium-pressure, and low-pressure steam turbine driven by the steam generated from the exhaust heat recovery boiler. A part of the steam at the steam turbine outlet is reheated by the reheater of the exhaust heat recovery boiler, and the high temperature part of the gas turbine is cooled and recovered by the rest of the steam at the high pressure steam turbine outlet. A closed steam cooling gas turbine combined plant that mixes with superheated steam reheated by a reheater of a heat recovery boiler and flows into the medium pressure steam turbine, wherein the waste heat recovery boiler includes a medium pressure superheater. Mixing part or all of the intermediate-pressure superheated steam generated by the intermediate-pressure superheater with the high-pressure steam turbine outlet steam that cools the high-temperature portion of the gas turbine, and cooling the high-temperature portion of the gas turbine. Features a closed steam-cooled gas turbine combined plant. 2. A gas turbine in which air and fuel compressed by a compressor are burned in a combustor, and a turbine driven by the obtained combustion gas is heat-exchanged between exhaust gas discharged from the gas turbine and feed water to produce a high-pressure gas. An exhaust heat recovery boiler for generating steam of three types of pressures, medium pressure and low pressure; and a high pressure, medium pressure, and low pressure steam turbine driven by the steam generated from the exhaust heat recovery boiler. A part of the steam is reheated by the reheater of the heat recovery steam generator, and the high temperature part of the gas turbine is cooled and recovered by the remaining steam at the outlet of the high pressure steam turbine. A closed steam-cooled gas turbine combined plant that mixes with superheated steam reheated by a heater and flows into the medium-pressure steam turbine, wherein the exhaust heat recovery boiler includes a medium-pressure superheater, and the gas turbine A part or all of the intermediate-pressure superheated steam generated by the intermediate-pressure superheater is mixed with the high-pressure steam turbine outlet steam that cools the high-temperature portion of the exhaust heat recovery boiler during rated operation. Wherein the temperature of the intermediate-pressure superheated steam generated in the step (b) is lower than the outlet steam temperature of the high-pressure steam turbine to cool a high-temperature portion of the gas turbine. 3. A gas turbine for driving air and fuel compressed by a compressor in a combustor and driving the turbine with the obtained combustion gas, and an exhaust gas and a feed water discharged from the gas turbine are heat-exchanged to produce a high-pressure gas. An exhaust heat recovery boiler for generating steam of three types of pressures, medium pressure and low pressure; and a high pressure, medium pressure, and low pressure steam turbine driven by the steam generated from the exhaust heat recovery boiler. A part of the steam is reheated by the reheater of the heat recovery steam generator, and the high temperature part of the gas turbine is cooled and recovered by the remaining steam at the outlet of the high pressure steam turbine. A closed steam-cooled gas turbine combined plant that mixes with superheated steam reheated by a heater and flows into the intermediate-pressure steam turbine, wherein the superheated steam that cools a high-temperature portion of the gas turbine and is recovered A valve for controlling the pressure of steam for cooling the high-temperature portion of the gas turbine on a pipe for supplying the superheated steam after being mixed with the superheated steam reheated by the reheater of the exhaust heat recovery boiler to the medium-pressure steam turbine A closed steam cooled gas turbine combined plant characterized by the installation of 4. A gas turbine, in which air and fuel compressed by a compressor are burned in a combustor, and the resulting combustion gas drives a turbine. An exhaust heat recovery boiler for generating steam of three types of pressures, medium pressure and low pressure; and a high pressure, medium pressure, and low pressure steam turbine driven by the steam generated from the exhaust heat recovery boiler. A part of the steam is reheated by the reheater of the heat recovery steam generator, and the high temperature part of the gas turbine is cooled and recovered by the remaining steam at the outlet of the high pressure steam turbine. A closed steam-cooled gas turbine combined plant that mixes with superheated steam reheated by a heater and flows into the intermediate-pressure steam turbine, wherein the superheated steam that cools a high-temperature portion of the gas turbine and is recovered A valve for controlling the pressure of steam for cooling the high-temperature portion of the gas turbine on a pipe for supplying the superheated steam after being mixed with the superheated steam reheated by the reheater of the exhaust heat recovery boiler to the medium-pressure steam turbine A closed steam-cooled gas turbine combined plant characterized by using at least an outlet air pressure of the compressor as a control variable of the valve. 5. A closed steam-cooled gas turbine combined plant according to claim 4, wherein an inlet pressure of said valve and an outlet air pressure of said compressor are used as control variables of said valve. 6. The method according to claim 4, wherein an air pressure at the outlet of the compressor and a steam pressure from the outlet of the high-pressure steam turbine or the outlet of the intermediate-pressure superheater to the high-temperature portion of the gas turbine are used as control variables of the valve. A closed steam-cooled gas turbine combined plant characterized by: 7. A closed steam system according to claim 4, wherein an air pressure at the outlet of the compressor and a steam pressure from the high temperature section of the gas turbine to a medium pressure steam turbine are used as control variables of the valve. Cooling gas turbine combined plant. 8. A gas turbine which burns air and fuel compressed by a compressor in a combustor and drives a turbine with the obtained combustion gas, and heat-exchanges exhaust gas and feed water discharged from the gas turbine to produce a high-pressure gas. An exhaust heat recovery boiler for generating steam of three types of pressures, medium pressure and low pressure; and a high pressure, medium pressure, and low pressure steam turbine driven by the steam generated from the exhaust heat recovery boiler. A part of the steam is reheated by the reheater of the heat recovery steam generator, and the high temperature part of the gas turbine is cooled and recovered by the remaining steam at the outlet of the high pressure steam turbine. A closed steam-cooled gas turbine combined plant that mixes with superheated steam reheated by a heater and flows into the intermediate-pressure steam turbine, comprising a stop valve at a high-pressure steam turbine inlet, and the stop valve A first pipe in which the previous steam flows to the condenser avoiding the high-pressure steam turbine, a first valve on the pipe, and any one of a portion from the high-pressure evaporator outlet of the exhaust heat recovery boiler to just before the first pipe. Closed steam cooling gas, comprising: a second pipe connecting the position of the gas turbine and a cooling steam supply pipe of the gas turbine hot section, and a second pipe on which high-pressure steam flows to the gas turbine hot section, and a second valve on the pipe. Turbine combined plant. 9. The system according to claim 8, wherein the first valve and the second valve are both opened when the stop valve is closed, and the first valve and the second valve are opened when the stop valve is open. Closed steam-cooled gas turbine combined plant characterized by closing both valves. 10. A gas turbine comprising a compressor for compressing air, a combustor for burning air and fuel compressed by the compressor, a turbine driven by combustion exhaust gas from the combustor, and exhaust gas from the gas turbine. An exhaust heat recovery boiler that generates steam using the exhaust gas to be discharged as a heat source, and a steam turbine that is driven by the steam generated by the exhaust heat recovery boiler. The steam turbine is supplied with steam generated by the exhaust heat recovery boiler. High pressure steam turbine, a reheater provided in the exhaust heat recovery boiler for reheating steam exiting from the high pressure steam turbine, a medium pressure turbine for supplying the reheated steam, and the medium pressure turbine And a low-pressure turbine for supplying steam exiting from the gas turbine, wherein the turbine has a cooling passage, and the steam exits from the high-pressure turbine. A part is supplied to the cooling passage of the turbine, and the steam that has passed through the cooling passage of the turbine is configured to be combined with the steam that has exited the reheater. Is combined with the cooled steam and supplied to the medium-pressure turbine, and the steam discharged from the high-pressure turbine is overheated from the exhaust heat recovery boiler at a lower temperature than the steam discharged from the high-pressure turbine. A gas turbine combined plant, which is configured to be supplied to a cooling flow path in the turbine after being mixed with steam.