STEAM COOLED GAS TURBINE SYSTEM WITH REGENERATIVE HEAT EXCHANGE

Abstract

Steam cooled gas turbine system is improved to enhance a gas turbine efficiency and a combined efficiency by effecting steam-cooling of a combustor transition piece and a turbine blade. In a combined cycle system comprising; a gas turbine (8) having a generator (1), a compressor (2), a combustor (3), a blade cooling air cooler (4), a fan (5) and a turbine (6); a steam turbine (29) having a high pressure turbine (21), an intermediate pressure turbine (22) and a low pressure turbine (23); and a waste heat recovery boiler (9), saturated water of a high pressure pump (27) is partially led into a heat exchanger (110) for cooling steam to be supplied into a moving blade (52) and a stationary blade (53). Also, outlet steam of the high pressure turbine (21) is led into the moving blade (52), the stationary blade (53) and the combustor transition piece (54) for cooling thereof and the steam is then supplied to an inlet of the intermediate pressure turbine (22). Further, the outlet steam of the high pressure turbine (21) is led into the turbine (6) for cooling blades thereof and the steam used for cooling the stationary blade is supplied to the inlet of the intermediate pressure turbine (22) and the steam used for cooling the moving blade is supplied to a reheater (20). Thus, the efficiency is enhanced.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to a steam cooled gas turbine system and more particularly to a steam cooled gas turbine system in which temperature and flow rate of cooling steam are efficiently controlled and heating of fuel and cooling of gas turbine blade cooling air are carried out by steam generated at a waste heat recovery boiler.

[0003] 2. Description of the Prior Art

[0004] FIG. 26 is a diagram of a steam cooled gas turbine system in the prior art. In FIG. 26, the prior art steam cooled gas turbine system is constructed by a gas turbine 8, a waste heat recovery boiler 9 and a steam turbine 29. In the gas turbine 8, suction air is taken into a compressor 2 to be compressed to a predetermined pressure and while the compressed air is partially used for cooling a gas turbine blade, the most part thereof is led into a combustor 3 to be mixed with fuel 7 for generation of a high temperature gas. The high temperature gas enters a turbine 6 to expand for work and a turbine output after deduction of a compressor output is converted into an electric power at a generator 1. On the other hand, outlet steam of a high pressure turbine 21 flowing through a piping 101 is partially taken to be supplied into the turbine 6 for cooling the gas turbine blade via a cooling steam supply piping 101a. This steam is heated by cooling a steam cooled blade 51 and is recovered into an inlet of an intermediate pressure turbine 22 via a cooling steam recovery piping 102. Thus, for cooling the gas turbine blade, the air bled from the compressor 2 and a portion of the outlet steam of the high pressure turbine 21 are used.

[0005] While outlet air of the compressor 2 is partially used for blade cooling in the turbine 6, this air, being of a high temperature, is cooled to a predetermined temperature at a blade cooling air cooler 4 using a cooling fan 5 and is then used for the turbine blade cooling. Thus, the air so led from the compressor 2 is once cooled at the blade cooling air cooler 4 using the cooling fan 5 to be then supplied into the turbine 6.

[0006] In the waste heat recovery boiler 9, outlet steam of a low pressure turbine 23 is converted into water from steam at a condenser 25. Then, the water is pressurized at a feed water pump 26 and heated at a feed water heater 10 to become saturated water. This saturated water is separated into three systems of water. The first one becomes saturated steam at a low pressure evaporator 11 and becomes superheated steam at a low pressure superheater 15 and is then supplied to an inlet of the low pressure turbine 23. The second one is pressurized to a predetermined pressure at an intermediate pressure pump 28, becomes saturated water at an intermediate pressure economizer 12, becomes saturated steam at an intermediate pressure evaporator 14 and becomes superheated steam at an intermediate pressure superheater 16 and is then supplied to an inlet of a reheater 20. And the third one is pressurized to a predetermined pressure at a high pressure pump 27, becomes saturated water at a first high pressure economizer 13 and a second high pressure economizer 17, becomes saturated steam at a high pressure evaporator 18 and becomes superheated steam at a high pressure superheater 19 and is then led into the high pressure turbine 21. The mentioned superheated steam enters the high pressure turbine 21, the intermediate pressure turbine 22 and the low pressure turbine 23, respectively, to expand for generating an output and this output is converted into an electric power at a generator 24.

[0007] With respect to the abovementioned cooling by steam, it is impossible to use the steam in a quantity in excess of that of the steam obtainable at the outlet of the high pressure turbine 21. Hence, in order to secure a spare quantity of the available steam, it is preferable to reduce the flow rate of the cooling steam to the extent possible. Also, if the cooling steam is made less in the quantity, it becomes possible to control the temperature of the steam, after used for the cooling, with less variation in the quantity of the cooling steam. Especially, if the temperature of the cooling steam heated by the cooling is maintained to a predetermined level, it will not only enhance the reliability and life of the cooled blade, rotor, pipings, etc. of the gas turbine but also it will ensure an operation without damaging the enhanced combined efficiency. In order to reduce the quantity of the cooling steam, it is necessary to reduce the temperature of the cooling steam.

[0008] Thus, while the temperature of the cooling steam is necessary to be maintained lower for enhancing the reliability of the cooled blade or the like, in the system shown in FIG. 26, the cooling steam supply temperature is decided by the outlet condition of the high pressure turbine 21 and it is difficult to further reduce the cooling steam temperature in this system.

[0009] Also, the air bled from the compressor for cooling the gas turbine blade is once cooled at the blade cooling air cooler 4 using the cooling fan 5 to be supplied into the turbine 6, as mentioned above, and the heat obtained by such cooling is discharged outside in vain. This causes a reduction in the thermal efficiency (gas turbine efficiency and combined efficiency) of the gas turbine and of a combined cycle system using this gas turbine. Moreover, the fuel 7 is supplied into the combustor 3 without being heated (preheated).

SUMMARY OF THE INVENTION

[0010] In view of the mentioned problem in the prior art, therefore, it is an object of the present invention to provide a steam cooled gas turbine system in which the system is made such that cooling of a turbine blade is done by steam partially taken from an outlet of a high pressure turbine and temperature of this steam is adjusted by cooling water taken from a waste heat recovery boiler, a cooling steam supply system is made such that a moving blade, a stationary blade and a combustor transition piece are supplied with steam via their respective separate systems so that the steam supplied to the stationary blade and the combustor transition piece may be of a temperature higher than that supplied to the moving blade to thereby obtain a higher effect of the cooling by steam in the respective steam systems and also preheating of fuel is done to thereby enhance the combined efficiency.

[0011] In order to achieve the mentioned object, the present invention provides the means of the following inventions (1) to (13):

[0012] (1) In a steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling a high temperature portion of the gas turbine including a high temperature portion of the combustor and a high temperature portion of a blade of the turbine; and a waste heat recovery boiler being fed with exhaust gas of the gas turbine so as to heat and vaporize condensed water coming from the condenser for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, it is characterized that there is provided in the cooling steam system a heat exchanger for effecting a heat exchange so that outlet steam of the high pressure turbine flowing through the heat exchanger is cooled to be supplied into at least one of the high temperature portions of the gas turbine for cooling thereof and is then recovered into the waste heat recovery boiler and cooling water coming from the waste heat recovery boiler and flowing through the heat exchanger is heated and is then recovered into the waste heat recovery boiler.

[0013] (2) In a steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling a high temperature portion of the gas turbine including a high temperature portion of the combustor and a high temperature portion of a blade of the turbine; and a waste heat recovery boiler being fed with exhaust gas of the gas turbine so as to heat and vaporize condensed water coming from the condenser for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, it is characterized that there are provided in the cooling steam system a water sprayer for leading a high pressure water from the waste heat recovery boiler via a demineralizer to be sprayed into a passage for leading cooling steam from an outlet of the high pressure turbine to be supplied into at least one of the high temperature portions of the gas turbine and a drain separator being interposed in a passage between the water sprayer and the at least one of the high temperature portions and the cooling steam of which drain has been removed by the drain separator is supplied into the at least one of the high temperature portions for cooling thereof and is then recovered into the waste heat recovery boiler.

[0014] (3) In the steam cooled gas turbine system as mentioned in the invention (1) or (2), it is characterized that the high temperature portion of the gas turbine is a moving blade.

[0015] (4) In the steam cooled gas turbine system as mentioned in the invention (1) or (2), it is characterized that the high temperature portion of the gas turbine is a stationary blade and the steam heated by cooling the stationary blade is recovered into the waste heat recovery boiler.

[0016] (5) In the steam cooled gas turbine system as mentioned in the invention (1) or (2), it is characterized that the high temperature portion of the gas turbine is a combustor transition piece and the steam heated by cooling the combustor transition piece is recovered into the waste heat recovery boiler.

[0017] (6) In the steam cooled gas turbine system as mentioned in the invention (1) or (2), it is characterized that the high temperature portion of the gas turbine is a moving blade and a stationary blade and the steam heated by cooling the stationary blade is recovered into the waste heat recovery boiler.

[0018] (7) In the steam cooled gas turbine system as mentioned in the invention (1) or (2), it is characterized that the high temperature portion of the gas turbine is a moving blade, a stationary blade and a combustor transition piece and the steam heated by cooling the stationary blade and the combustor transition piece is recovered into the waste heat recovery boiler.

[0019] (8) In the steam cooled gas turbine system as mentioned in the invention (1) or (2), it is characterized that the high temperature portion of the gas turbine is a stationary blade and a combustor transition piece and the steam heated by cooling the stationary blade and the combustor transition piece is recovered into the waste heat recovery boiler.

[0020] (9) In the steam cooled gas turbine system as mentioned in any one of the inventions (1) to (8), it is characterized that there is provided in the cooling steam system a flow regulating valve for regulating a flow rate of the steam so as to correspond to a cooling ability of the high temperature portion of the gas turbine.

[0021] (10) In the steam cooled gas turbine system as mentioned in the invention (9), it is characterized that there is provided in a fuel inflow passage of the combustor of the gas turbine a fuel heater for heating fuel by steam coming from the waste heat recovery boiler and the steam cooled by heating the fuel is recovered into a feed water heater, and it is further characterized that a portion of outlet water of the feed water heater is taken to flow through a blade cooling air cooler for cooling blade cooling air of the turbine and the water heated by cooling the blade cooling air is recovered into the waste heat recovery boiler.

[0022] (11) In a steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low-pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling the combustor and a blade of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a first high pressure economizer, a second high pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator, a reheater, etc. and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, it is characterized that there is provided in the cooling steam system a heat exchanger for effecting a heat exchange so that outlet steam of the high pressure turbine flowing through the heat exchanger is cooled to be supplied into a moving blade of the gas turbine for cooling thereof and is then recovered into the reheater and cooling water coming from the first high pressure economizer and flowing through the heat exchanger is heated and is then recovered into the high pressure evaporator.

[0023] (12) In a steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling the combustor and a blade of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a first high pressure economizer, a second high pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator, a reheater, etc. and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, it is characterized that there are provided in the cooling steam system a water spray rate control valve for leading a high pressure water from the feed water heater, a demineralizer being connected to the water spray rate control valve, a water sprayer being connected to the demineralizer for spraying the high pressure water into a passage for leading cooling steam from an outlet of the high pressure turbine to be supplied into a moving blade of the gas turbine and a drain separator being interposed in a passage between the water sprayer and the moving blade and the cooling steam of which drain has been removed by the drain separator is supplied into the moving blade for cooling thereof and is then recovered into the reheater.

[0024] (13) In a steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling the combustor and a blade of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a first high pressure economizer, a second high pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator, a reheater, etc. and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, it is characterized that there are provided in the cooling steam system a water spray rate control valve for leading a high pressure water from the feed water heater, a demineralizer being connected to the water spray rate control valve, a water sprayer being connected to the demineralizer for spraying the high pressure water into a passage for leading cooling steam from an outlet of the high pressure turbine to be supplied into a moving blade of the gas turbine and a drain separator being interposed in a passage between the water sprayer and the moving blade and the cooling steam of which drain has been removed by the drain separator is supplied into the moving blade for cooling thereof and is then recovered into the reheater, and it is further characterized that there are provided a heat exchanger side flow regulating valve near a steam inlet of the reheater in an outlet steam piping of the high pressure turbine connecting to the steam inlet of the reheater and an outflow side flow regulating valve in a cooling steam outlet passage of each of the moving blade, a stationary blade and a combustor transition piece, and it is still further characterized that there is provided in a fuel inflow passage of the combustor a fuel heater for heating fuel by outlet steam of the intermediate pressure economizer and the steam cooled by heating the fuel is recovered into the feed water heater, and it is still further characterized that a portion of outlet water of the feed water heater is taken to flow through a blade cooling air cooler for cooling blade cooling air of the turbine and the water heated by cooling the blade cooling air is recovered into the high pressure evaporator.

[0025] In the invention (1), a portion of the high pressure turbine outlet steam is extracted to be used as cooling steam. This steam is cooled at the heat exchanger to be then supplied into the high temperature portion of the gas turbine. The steam heated by so cooling the high temperature portion of the gas turbine is recovered into the waste heat recovery boiler. On the other hand, for cooling the steam at the heat exchanger, a portion of water of the waste heat recovery boiler is taken as cooling water to be supplied into the heat exchanger. This water heated by so cooling the steam is recovered into an inlet side, or a high temperature side, of the waste heat recovery boiler. In a system in which the heat given to the cooling water at the heat exchanger is discharged outside, the combined efficiency is reduced. However, in the invention (1), this heat given to the cooling water is recovered into the high temperature side of the waste heat recovery boiler. Thereby, without the combined efficiency being hurt, the effect to reduce the temperature of the cooling steam for cooling the high temperature portion of the gas turbine can be obtained. Thus, according to the system of the present invention, while the combined efficiency is in no case reduced, the reduction in the supply temperature and supply quantity of the cooling steam becomes possible. Moreover, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0026] In the invention (2), the system is constructed such that the heat exchanger as used in the invention (1) is eliminated and instead a water spraying device, including the water spray rate control valve, the demineralizer, the water sprayer and the drain separator, for spraying water taken from the waste heat recovery boiler is employed. By such construction, the water spray rate is controlled by the water spray rate control valve and control of the supply temperature of the cooling steam for cooling the high temperature portion of the gas turbine can be done more quickly than in the invention (1). The demineralizer is such one as is usually used for removing dissolved minerals in the condenser of a supercritical pressure plant or a nuclear plant and impurities in the water are removed by the demineralizer. Also, the drain separator is used for separating drain that is generated in a small quantity after the water is sprayed into the steam by the water sprayer so that the cooling steam of which drain has been removed is supplied for the cooling. Thus, as the feature of the present invention, a quicker reduction in the supply temperature and supply quantity of the cooling steam of the gas turbine high temperature portion becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0027] In the inventions (3) to (8), the respective high temperature portions of the gas turbine to be cooled in the invention (1) or (2) are selected as follows: the moving blade only in the invention (3), the stationary blade only in the invention (4), the combustor transition piece only in the invention (5), the moving blade and stationary blade in the invention (6), the moving blade, stationary blade and combustor transition piece in the invention (7) and the stationary blade and combustor transition piece in the invention (8). Thereby, the respective portions of the gas turbine are cooled and, like in the invention (1) or (2), reduction in the respective supply temperature and supply quantity of the cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0028] In the invention (9), the flow regulating valve is provided at each appropriate position in the cooling steam system and, by opening and closing the valves, the supply temperature of the cooling steam for cooling the gas turbine high temperature portion becomes controllable at any load state from the rated load to the partial load. Thereby, the supply temperature of the cooling steam becomes controllable without changing the supply quantity of the cooling steam and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured. Also, control of the respective recovery steam temperature becomes possible and thereby the reliability and life elongation of the cooled blade, rotor and pipings can be ensured. In each of the flow regulating valves, if the valve is operated to the opening side, the supply quantity of the cooling steam is increased and the recovery temperature of the cooling steam is reduced. If the valve is operated to the closing side, the supply quantity of the cooling steam is reduced and the recovery temperature of the cooling steam is elevated. In the construction using the water spray rate control valve, demineralizer, water sprayer and drain separator, the water spray rate is controlled by the water spray rate control valve and, by adding the flow regulating valves to this construction, a quick control of the supply temperature of the cooling steam to be supplied into the gas turbine high temperature portion becomes possible. Also, as described with respect to the invention (2), the quick reduction in the supply temperature and supply quantity of the cooling steam becomes possible as well as the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0029] In the invention (10), the fuel is heated at the fuel heater. Also, a portion of water on an outlet side, or a low temperature side, of the waste heat recovery boiler is taken to be supplied into the blade cooling air cooler for effecting a heat exchange. At the blade cooling air cooler, the water cools the blade cooling air to be supplied into the gas turbine high temperature portion and the water heated by cooling the air is then recovered into the waste heat recovery boiler. Thus, the heat that has been so far discharged outside by the cooling fan is recovered into the waste heat recovery boiler and the combined efficiency is enhanced.

[0030] In the invention (11), in order to cool the steam cooled moving blade, a portion of the high pressure turbine outlet steam is extracted to be used as cooling steam for the steam cooled moving blade. This steam is cooled at the heat exchanger to be then supplied into the steam cooled moving blade of the gas turbine. The steam heated by so cooling the moving blade is recovered into the middle portion of the reheater. On the other hand, for cooling the steam at the heat exchanger, a portion of outlet water of the first high pressure economizer is taken as cooling water to be supplied into the heat exchanger. This water heated by so cooling the steam is recovered into an inlet of the high pressure evaporator. In a system in which the heat given to the cooling water at the heat exchanger is discharged outside, the combined efficiency is reduced. However, in the invention (11), this heat given to the cooling water is recovered into the inlet side, or the high temperature side, of the waste heat recovery boiler. Thereby, without the combined efficiency being hurt, the effect to reduce the temperature of the cooling steam for cooling the high temperature portion of the gas turbine can be obtained. Thus, according to the system of the present invention, while the combined efficiency is in no case reduced, the reduction in the supply temperature and supply quantity of the cooling steam becomes possible. Moreover, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0031] In the invention (12), the system is constructed such that the heat exchanger as used in the invention (11) is eliminated and instead a water spraying device, including the water spray rate control valve, the demineralizer, the water sprayer and the drain separator, for spraying water taken from the outlet water of the high pressure pump is employed. By such construction, the water spray rate is controlled by the water spray rate control valve and control of the supply temperature of the cooling steam for cooling the moving blade of the gas turbine can be done more quickly than in the invention (11). The demineralizer is such one as is usually used for removing dissolved minerals in the condenser of a supercritical pressure plant or a nuclear plant and impurities in the water are removed by the demineralizer. Also, the drain separator is used for separating drain that is generated in a small quantity after the water is sprayed into the steam by the water sprayer so that the cooling steam of which drain has been removed is supplied for the cooling. Thus, as the feature of the present invention, a quicker reduction in the supply temperature and supply quantity of the cooling steam for cooling the moving blade becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0032] In the invention (13), the construction is made such that the heat exchanger is eliminated and instead, like in the invention (12), the water spray rate control valve, demineralizer, water sprayer and drain separator are employed. By such construction, the water spray rate is controlled by the water spray rate control valve and a quicker control of the supply temperature of the moving blade cooling steam becomes possible. Also, by cooling the blade cooling air at the blade cooling air cooler, the moving blade is cooled efficiently and, as described with respect to the invention (12), the quicker reduction in the supply temperature and supply quantity of the moving blade cooling steam becomes possible. Further, by controlling the flow regulating valves, the flow rate of the steam can be controlled appropriately. Thus, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a diagram of a steam cooled gas turbine system of a first embodiment according to the present invention.

[0034] FIG. 2 is a diagram of a steam cooled gas turbine system of a second embodiment according to the present invention.

[0035] FIG. 3 is a diagram of a steam cooled gas turbine system of a third embodiment according to the present invention.

[0036] FIG. 4 is a diagram of a steam cooled gas turbine system of a fourth embodiment according to the present invention.

[0037] FIG. 5 is a diagram of a steam cooled gas turbine system of a fifth embodiment according to the present invention.

[0038] FIG. 6 is a diagram of a steam cooled gas turbine system of a sixth embodiment according to the present invention.

[0039] FIG. 7 is a diagram of a steam cooled gas turbine system of a seventh embodiment according to the present invention.

[0040] FIG. 8 is a diagram of a steam cooled gas turbine system of an eighth embodiment according to the present invention.

[0041] FIG. 9 is a diagram of a steam cooled gas turbine system of a ninth embodiment according to the present invention.

[0042] FIG. 10 is a diagram of a steam cooled gas turbine system of a tenth embodiment according to the present invention.

[0043] FIG. 11 is a diagram of a steam cooled gas turbine system of an eleventh embodiment according to the present invention.

[0044] FIG. 12 is a diagram of a steam cooled gas turbine system of a twelfth embodiment according to the present invention.

[0045] FIG. 13 is a diagram of a steam cooled gas turbine system of a thirteenth embodiment according to the present invention.

[0046] FIG. 14 is a diagram of a steam cooled gas turbine system of a fourteenth embodiment according to the present invention.

[0047] FIG. 15 is a diagram of a steam cooled gas turbine system of a fifteenth embodiment according to the present invention.

[0048] FIG. 16 is a diagram of a steam cooled gas turbine system of a sixteenth embodiment according to the present invention.

[0049] FIG. 17 is a diagram of a steam cooled gas turbine system of a seventeenth embodiment according to the present invention.

[0050] FIG. 18 is a diagram of a steam cooled gas turbine system of an eighteenth embodiment according to the present invention.

[0051] FIG. 19 is a diagram of a steam cooled gas turbine system of a nineteenth embodiment according to the present invention.

[0052] FIG. 20 is a diagram of a steam cooled gas turbine system of a twentieth embodiment according to the present invention.

[0053] FIG. 21 is a diagram of a steam cooled gas turbine system of a twenty-first embodiment according to the present invention.

[0054] FIG. 22 is a diagram of a steam cooled gas turbine system of a twenty-second embodiment according to the present invention.

[0055] FIG. 23 is a diagram of a steam cooled gas turbine system of a twenty-third embodiment according to the present invention.

[0056] FIG. 24 is a diagram of a steam cooled gas turbine system of a twenty-fourth embodiment according to the present invention.

[0057] FIG. 25 is a diagram of a steam cooled gas turbine system of a twenty-fifth embodiment according to the present invention.

[0058] FIG. 26 is a diagram of a steam cooled gas turbine system in the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] Herebelow, embodiments according to the present invention will be described concretely with reference to figures.

[0060] FIG. 1 is a diagram of a steam cooled gas turbine system of a first embodiment according to the present invention. In FIG. 1, the steam cooled gas turbine system of the first embodiment is constructed by a gas turbine 8, a waste heat recovery boiler 9 and a steam turbine 29. In the gas turbine 8, suction air is taken into a compressor 2 to be compressed to a predetermined pressure and while the compressed air is partially used for cooling a gas turbine blade, the most part thereof is led into a combustor 3 to be mixed with fuel for generation of a high temperature gas. The high temperature gas enters a turbine 6 to expand for work and a turbine output after deduction of a compressor output is converted into an electric power at a generator 1.

[0061] In the waste heat recovery boiler 9, outlet steam of a low pressure turbine 23 is converted into water from steam at a condenser 25. Then, the water is pressurized at a feed water pump 26 and heated at a feed water heater 10 to become saturated water. This saturated water is separated into three systems of water. The first one becomes saturated steam at a low pressure evaporator 11 and becomes superheated steam at a low pressure superheater 15 and is then supplied to an inlet of the low pressure turbine 23. The second one is pressurized to a predetermined pressure at an intermediate pressure pump 28, becomes saturated water at an intermediate pressure economizer 12, becomes saturated steam at an intermediate pressure evaporator 14 and becomes superheated steam at an intermediate pressure superheater 16 and is then supplied to an inlet of a reheater 20. And the third one is pressurized to a predetermined pressure at a high pressure pump 27, becomes saturated water at a first high pressure economizer 13 and a second high pressure economizer 17, becomes saturated steam at a high pressure evaporator 18 and becomes superheated steam at a high pressure superheater 19 and is then led into a high pressure turbine 21. The mentioned superheated steam enters the high pressure turbine 21, an intermediate pressure turbine 22 and the low pressure turbine 23, respectively, to expand for generating an output and this output is converted into an electric power at a generator 24.

[0062] In the present embodiment of FIG. 1, the portion corresponding to the cooled blade 51 in the prior art shown in FIG. 26 is divided into a steam cooled moving blade 52, a steam cooled stationary blade 53 and a steam cooled combustor transition piece 54. As for the steam cooled moving blade 52, in which the temperature of the steam, after used for the cooling, is low, outlet steam of the high pressure turbine 21 flowing through a piping 101 is partially extracted for cooling the steam cooled moving blade via a piping 109 and is cooled at a heat exchanger 110 to be supplied into the steam cooled moving blade 52 via a moving blade cooling steam supply piping 103. The steam heated by cooling the steam cooled moving blade 52 is recovered into a middle portion of the reheater 20 via a moving blade cooling steam recovery piping 104. For the cooling of the moving blade cooling steam at the heat exchanger 110, cooled water is partially taken from an outlet of the first high pressure economizer 13 and is supplied into the heat exchanger 110 via a piping 111 to be used for cooling the moving blade cooling steam. The water heated at the heat exchanger 110 is supplied into an inlet of the high pressure evaporator 18 via a piping 112.

[0063] In the present first embodiment constructed as above, if the construction is so made that the heat obtained by cooling the moving blade cooling steam at the heat exchanger 110 would be discharged outside, then it will bring forth a reduction in the combined efficiency, but actually in the present first embodiment, the heat obtained at the heat exchanger 110 is recovered into the inlet of the high pressure evaporator 18. By this arrangement, while there is no reduction in the combined efficiency, a reduction in the supply temperature and supply quantity of the moving blade cooling steam becomes possible. Moreover, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Thus, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured. As for the cooling of the steam cooled stationary blade 53 and the steam cooled combustor transition piece 54, steam extracted from the outlet steam of the high pressure turbine 21 is supplied into them via a stationary blade cooling steam supply piping 105 and a combustor transition piece cooling steam supply piping 107, respectively. Numerals 106 and 108 designate a stationary blade cooling steam recovery piping and a combustor transition piece cooling steam recovery piping, respectively. It is to be noted that reference numerals shown in FIG. 1 but not specifically described are the same as those of the prior art shown in FIG. 26.

[0064] FIG. 2 is a diagram of a steam cooled gas turbine system of a second embodiment according to the present invention. In the present second embodiment, as compared with the first embodiment shown in FIG. 1 where the moving blade cooling steam only is cooled at the heat exchanger 110, the stationary blade cooling steam also is flown through the heat exchanger 110 to be cooled there and is supplied into the steam cooled stationary blade 53 for cooling thereof via a stationary blade cooling steam supply piping 105a.

[0065] By this arrangement, while there is no reduction in the combined efficiency, a reduction in the supply temperature and supply quantity of the stationary blade and moving blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Thus, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0066] FIG. 3 is a diagram of a steam cooled gas turbine system of a third embodiment according to the present invention. In the present third embodiment, as compared with the second embodiment shown in FIG. 2 where the moving blade and stationary blade cooling steam is cooled at the heat exchanger 110, the combustor transition piece cooling steam also is flown through the heat exchanger 110 to be cooled there and is supplied into the combustor transition piece 54 for cooling thereof via a combustor transition piece cooling steam supply piping 107a.

[0067] By this arrangement, while there is no reduction in the combined efficiency, a reduction in the cooling steam supply temperature and supply quantity of the combustor transition piece, stationary blade and moving blade becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Thus, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0068] FIG. 4 is a diagram of a steam cooled gas turbine system of a fourth embodiment according to the present invention. In the present fourth embodiment, as compared with the first embodiment shown in FIG. 1 where the cooling steam for cooling the combustor transition piece 54 is taken from the outlet steam of the high pressure turbine 21, the system is so made that the cooling steam for cooling the combustor transition piece 54 is taken from outlet steam of the intermediate pressure superheater 16 via a combustor transition piece cooling steam supply piping 107b and is recovered into an inlet of the intermediate pressure turbine 22.

[0069] By this arrangement, the flow rate of the cooling steam extracted from the outlet of the high pressure turbine 21 via the piping 109 is reduced by the flow rate of the cooling steam supplied through the piping 107b and thereby a spare quantity of the available steam can be ensured.

[0070] FIG. 5 is a diagram of a steam cooled gas turbine system of a fifth embodiment according to the present invention. In the present fifth embodiment, as compared with the third embodiment shown in FIG. 3 where the cooling steam for cooling the combustor transition piece 54 is taken from the outlet steam of the heat exchanger 110, the system is so made that the cooling steam for cooling the combustor transition piece 54 is taken from the outlet steam of the intermediate pressure superheater 16 via the combustor transition piece cooling steam supply piping 107b and is recovered into the inlet of the intermediate pressure turbine 22.

[0071] By this arrangement, the flow rate of the cooling steam extracted from the outlet of the high pressure turbine 21 via the piping 109 is reduced by the flow rate of the cooling steam supplied through the piping 107b and thereby a spare quantity of the available steam can be ensured.

[0072] It is to be noted that, in the mentioned first to fifth embodiments, while the cases where the cooling steam cooled at the heat exchanger 110 is used for cooling the moving blade 52 only (FIGS. 1 and 4), the moving blade 52 and stationary blade 53 (FIGS. 2 and 5) and the moving blade 52, stationary blade 53 and combustor transition piece 54 (FIG. 3) have been described, the cases are not limited thereto but, for example, the cooling steam cooled at the heat exchanger 110 may be used for cooling the stationary blade 53 only, although not illustrated, and in this case also, the same effect can be obtained.

[0073] FIG. 6 is a diagram of a steam cooled gas turbine system of a sixth embodiment according to the present invention. In the present sixth embodiment, as compared with the first embodiment shown in FIG. 1, the system is so made that a flow regulating valve 151 in the piping 109, a piping 113 connecting the piping 101 and the piping 103 and a flow regulating valve 152 in the piping 113 are added and, by opening and closing these valves 151, 152, the supply temperature of the moving blade cooling steam becomes adjustable in any load state from the rating to the partial load. Further, a piping 117 connecting the piping 111 and the piping 112, a flow regulating valve 157 in the piping 117 and a flow regulating valve 158 in the piping 111 are added and, by opening and closing these valves 157, 158, the supply temperature of the moving blade cooling steam can be controlled quickly and securely.

[0074] By the above arrangement, the steam temperature at the outlet of the moving blade becomes adjustable without changing the flow rate of the steam supplied and there is obtained the effect to ensure the reliability and life elongation of the moving blade, rotor and pipings. In order to reduce the cooling steam temperature of the moving blade, the flow regulating valve 151 is operated to the opening side and the flow regulating valve 152 to the closing side. Or the flow regulating valve 157 is operated to the closing side and the flow regulating valve 158 to the opening side and thereby the cooled water flowing into the heat exchanger 110 is increased and the cooling steam temperature is reduced. Also, in order to elevate the cooling steam temperature of the moving blade, the flow regulating valve 151 is operated to the closing side and the flow regulating valve 152 to the opening side. Or the flow regulating valve 157 is operated to the opening side and the flow regulating valve 158 to the closing side and thereby the cooled water flowing into the heat exchanger 110 is suppressed and the cooling steam temperature is elevated.

[0075] Moreover, as compared with the first embodiment shown in FIG. 1, a flow regulating valve 153 in the piping 101, a flow regulating valve 154 in the piping 104, a flow regulating valve 155 in the piping 106 and a flow regulating valve 156 in the piping 108 are added and, by opening and closing these valves 153 to 156, the flow rate of the cooling steam of the moving blade, stationary blade and combustor transition piece becomes adjustable. Thereby, not only in the rating time but also in the partial load time, the temperature of the respective recovery steam can be controlled and there is obtained the effect to ensure the reliability and life elongation of the moving and stationary blades, combustor transition piece, rotor and pipings. If the respective flow regulating valves are operated to the opening side, the flow rate of the steam supplied increases and the temperature of the respective recovery steam is reduced. Also, if the respective flow regulating valves are operated to the closing side, the flow rate of the steam supplied is reduced and the temperature of the respective recovery steam is elevated.

[0076] FIG. 7 is a diagram of a steam cooled gas turbine system of a seventh embodiment according to the present invention. In the present seventh embodiment, as compared with the second embodiment shown in FIG. 2, the system is so made that a flow regulating valve 151 in the piping 109, a piping 113 connecting the piping 101 and the piping 103 and a flow regulating valve 152 in the piping 113 are added and, by opening and closing these valves 151, 152, the supply temperature of the moving blade and stationary blade cooling steam becomes adjustable in any load state from the rating to the partial load. Further, a piping 117 connecting the piping 111 and the piping 112, a flow regulating valve 157 in the piping 117 and a flow regulating valve 158 in the piping 111 are added and, by opening and closing these valves 157, 158, the supply temperature of the moving blade and stationary blade cooling steam can be controlled quickly and securely.

[0077] By the above arrangement, the steam temperature at the outlets of the moving blade and stationary blade becomes adjustable without changing the flow rate of the steam supplied and there is obtained the effect to ensure the reliability and life elongation of the moving blade, stationary blade, rotor and pipings. In order to reduce the cooling steam temperature of the moving blade and the stationary blade, the flow regulating valve 151 is operated to the opening side and the flow regulating valve 152 to the closing side. Or the flow regulating valve 157 is operated to the closing side and the flow regulating valve 158 to the opening side and thereby the cooled water flowing into the heat exchanger 110 is increased and the cooling steam temperature is reduced. Also, in order to elevate the cooling steam temperature of the moving blade and the stationary blade, the flow regulating valve 151 is operated to the closing side and the flow regulating valve 152 to the opening side. Or the flow regulating valve 157 is operated to the opening side and the flow regulating valve 158 to the closing side and thereby the cooled water flowing into the heat exchanger 110 is suppressed and the cooling steam temperature is elevated.

[0078] Moreover, as compared with the second embodiment shown in FIG. 2, a flow regulating valve 153 in the piping 101, a flow regulating valve 154 in the piping 104, a flow regulating valve 155 in the piping 106 and a flow regulating valve 156 in the piping 108 are added and, by opening and closing these valves 153 to 156, the flow rate of the cooling steam of the moving blade, stationary blade and combustor transition piece becomes adjustable. Thereby, not only in the rating time but also in the partial load time, the temperature of the respective recovery steam can be controlled and there is obtained the effect to ensure the reliability and life elongation of the moving and stationary blades, combustor transition piece, rotor and pipings. If the respective flow regulating valves are operated to the opening side, the flow rate of the steam supplied increases and the temperature of the respective recovery steam is reduced. Also, if the respective flow regulating valves are operated to the closing side, the flow rate of the steam supplied is reduced and the temperature of the respective recovery steam is elevated.

[0079] FIG. 8 is a diagram of a steam cooled gas turbine system of an eighth embodiment according to the present invention. In the present eighth embodiment, as compared with the third embodiment shown in FIG. 3, the system is so made that a flow regulating valve 151 in the piping 109, a piping 113 connecting the piping 101 and the piping 103 and a flow regulating valve 152 in the piping 113 are added and, by opening and closing these valves 151, 152, the supply temperature of the moving blade and stationary blade cooling steam and of the combustor transition piece cooling steam becomes adjustable in any load state from the rating to the partial load. Further, a piping 117 connecting the piping 111 and the piping 112, a flow regulating valve 157 in the piping 117 and a flow regulating valve 158 in the piping 111 are added and, by opening and closing these valves 157, 158, the supply temperature of the moving blade and stationary blade cooling steam and of the combustor transition piece cooling steam can be controlled quickly and securely.

[0080] By the above arrangement, the steam temperature at the outlets of the moving blade and the stationary blade as well as of the combustor transition piece becomes adjustable without changing the flow rate of the steam supplied and there is obtained the effect to ensure the reliability and life elongation of the moving blade, stationary blade, combustor transition piece, rotor and pipings. In order to reduce the cooling steam temperature of the moving blade and the stationary blade as well as of the combustor transition piece, the flow regulating valve 151 is operated to the opening side and the flow regulating valve 152 to the closing side. Or the flow regulating valve 157 is operated to the closing side and the flow regulating valve 158 to the opening side and thereby the cooled water flowing into the heat exchanger 110 is increased and the cooling steam temperature is reduced. Also, in order to elevate the cooling steam temperature of the moving blade and the stationary blade as well as of the combustor transition piece, the flow regulating valve 151 is operated to the closing side and the flow regulating valve 152 to the opening side. Or the flow regulating valve 157 is operated to the opening side and the flow regulating valve 158 to the closing side and thereby the cooled water flowing into the heat exchanger 110 is suppressed and the cooling steam temperature is elevated.

[0081] Moreover, as compared with the third embodiment shown in FIG. 3, a flow regulating valve 153 in the piping 101, a flow regulating valve 154 in the piping 104, a flow regulating valve 155 in the piping 106 and a flow regulating valve 156 in the piping 108 are added and, by opening and closing these valves 153 to 156, the flow rate of the cooling steam of the moving blade, stationary blade and combustor transition piece becomes adjustable. Thereby, not only in the rating time but also in the partial load time, the temperature of the respective recovery steam can be controlled and there is obtained the effect to ensure the reliability and life elongation of the moving and stationary blades, combustor transition piece, rotor and pipings. If the respective flow regulating valves are operated to the opening side, the flow rate of the steam supplied increases and the temperature of the respective recovery steam is reduced. Also, if the respective flow regulating valves are operated to the closing side, the flow rate of the steam supplied is reduced and the temperature of the respective recovery steam is elevated.

[0082] FIG. 9 is a diagram of a steam cooled gas turbine system of a ninth embodiment according to the present invention. In the present ninth embodiment, as compared with the fourth embodiment shown in FIG. 4, the system is so made that a flow regulating valve 151 in the piping 109, a piping 113 connecting the piping 101 and the piping 103 and a flow regulating valve 152 in the piping 113 are added and, by opening and closing these valves 151, 152, the supply temperature of the moving blade cooling steam becomes adjustable in any load state from the rating to the partial load. Further, a piping 117 connecting the piping 111 and the piping 112, a flow regulating valve 157 in the piping 117 and a flow regulating valve 158 in the piping 111 are added and, by opening and closing these valves 157, 158, the supply temperature of the moving blade cooling steam can be controlled quickly and securely.

[0083] By the above arrangement, the steam temperature at the outlet of the moving blade becomes adjustable without changing the flow rate of the steam supplied and there is obtained the effect to ensure the reliability and life elongation of the moving blade, rotor and pipings. In order to reduce the cooling steam temperature of the moving blade, the flow regulating valve 151 is operated to the opening side and the flow regulating valve 152 to the closing side. Or the flow regulating valve 157 is operated to the closing side and the flow regulating valve 158 to the opening side and thereby the cooled water flowing into the heat exchanger 110 is increased and the cooling steam temperature is reduced. Also, in order to elevate the cooling steam temperature of the moving blade, the flow regulating valve 151 is operated to the closing side and the flow regulating valve 152 to the opening side. Or the flow regulating valve 157 is operated to the opening side and the flow regulating valve 158 to the closing side and thereby the cooled water flowing into the heat exchanger 110 is suppressed and the cooling steam temperature is elevated.

[0084] Moreover, as compared with the fourth embodiment shown in FIG. 4, a flow regulating valve 153 in the piping 101, a flow regulating valve 154 in the piping 104, a flow regulating valve 155 in the piping 106 and a flow regulating valve 156 in the piping 108 are added and, by opening and closing these valves 153 to 156, the flow rate of the cooling steam of the moving blade, stationary blade and combustor transition piece becomes adjustable. Thereby, not only in the rating time but also in the partial load time, the temperature of the respective recovery steam can be controlled and there is obtained the effect to ensure the reliability and life elongation of the moving and stationary blades, combustor transition piece, rotor and pipings. If the respective flow regulating valves are operated to the opening side, the flow rate of the steam supplied increases and the temperature of the respective recovery steam is reduced. Also, if the respective flow regulating valves are operated to the closing side, the flow rate of the steam supplied is reduced and the temperature of the respective recovery steam is elevated.

[0085] FIG. 10 is a diagram of a steam cooled gas turbine system of a tenth embodiment according to the present invention. In the present tenth embodiment, as compared with the fifth embodiment shown in FIG. 5, the system is so made that a flow regulating valve 151 in the piping 109, a piping 113 connecting the piping 101 and the piping 103 and a flow regulating valve 152 in the piping 113 are added and, by opening and closing these valves 151, 152, the flow rate of the moving blade and stationary blade cooling steam is held constant and the supply temperature of the moving blade and stationary blade cooling steam becomes adjustable in any load state from the rating to the partial load. Further, a piping 117 connecting the piping 111 and the piping 112, a flow regulating valve 157 in the piping 117 and a flow regulating valve 158 in the piping 111 are added and, by opening and closing these valves 157, 158, the supply temperature of the moving blade and stationary blade cooling steam can be controlled quickly and securely.

[0086] By the above arrangement, the steam temperature at the outlets of the moving blade and the stationary blade becomes adjustable without changing the flow rate of the steam supplied and there is obtained the effect to ensure the reliability and life elongation of the moving blade, stationary blade, rotor and pipings. In order to reduce the cooling steam temperature of the moving blade and the stationary blade, the flow regulating valve 151 is operated to the opening side and the flow regulating valve 152 to the closing side. Or the flow regulating valve 157 is operated to the closing side and the flow regulating valve 158 to the opening side and thereby the cooled water flowing into the heat exchanger 110 is increased and the cooling steam temperature is reduced. Also, in order to elevate the cooling steam temperature of the moving blade and the stationary blade, the flow regulating valve 151 is operated to the closing side and the flow regulating valve 152 to the opening side. Or the flow regulating valve 157 is operated to the opening side and the flow regulating valve 158 to the closing side and thereby the cooled water flowing into the heat exchanger 110 is suppressed and the cooling steam temperature is elevated.

[0087] Moreover, as compared with the fifth embodiment shown in FIG. 5, a flow regulating valve 153 in the piping 101, a flow regulating valve 154 in the piping 104, a flow regulating valve 155 in the piping 106 and a flow regulating valve 156 in the piping 108 are added and, by opening and closing these valves 153 to 156, the flow rate of the cooling steam of the moving blade, stationary blade and combustor transition piece becomes adjustable. Thereby, not only in the rating time but also in the partial load time, the temperature of the respective recovery steam can be controlled and there is obtained the effect to ensure the reliability and life elongation of the moving and stationary blades, combustor transition piece, rotor and pipings. If the respective flow regulating valves are operated to the opening side, the flow rate of the steam supplied increases and the temperature of the respective recovery steam is reduced. Also, if the respective flow regulating valves are operated to the closing side, the flow rate of the steam supplied is reduced and the temperature of the respective recovery steam is elevated.

[0088] FIG. 11 is a diagram of a steam cooled gas turbine system of an eleventh embodiment according to the present. invention. In the present eleventh embodiment, as compared with the sixth embodiment shown in FIG. 6, the system is so made that saturated steam partially extracted from an outlet of the intermediate pressure economizer 12 is flown through a fuel heater 202 via a piping 201 for heating the fuel 7 and is then supplied to an inlet of the feed water heater 10 via a piping 203. By this arrangement, the fuel 7 is heated and the flow rate of the fuel is reduced. Thus, the gas turbine efficiency and the combined efficiency are enhanced.

[0089] Also, as compared with the sixth embodiment shown in FIG. 6, outlet water of the high pressure pump 27 is partially taken via a piping 204 to be supplied into the blade cooling air cooler 4. At the blade cooling air cooler 4, the water is heated by cooling air taken from the compressor 2 and the cooling air is cooled. The water is then recovered into an inlet of the high pressure evaporator 18. By this arrangement, the heat as has so far been discharged outside in vain by the cooling fan is recovered into the waste heat recovery boiler 9 and the combined efficiency is enhanced.

[0090] FIG. 12 is a diagram of a steam cooled gas turbine system of a twelfth embodiment according to the present invention. In the present twelfth embodiment, as compared with the seventh embodiment shown in FIG. 7, the system is so made that saturated steam partially extracted from the outlet of the intermediate pressure economizer 12 is flown through the fuel heater 202 via the piping 201 for heating the fuel 7 and is then supplied to the inlet of the feed water heater 10 via the piping 203. By this arrangement, the fuel 7 is heated and the flow rate of the fuel is reduced. Thus, the gas turbine efficiency and the combined efficiency are enhanced.

[0091] Also, as compared with the seventh embodiment shown in FIG. 7, outlet water of the high pressure pump 27 is partially taken via the piping 204 to be supplied into the blade cooling air cooler 4. At the blade cooling air cooler 4, the water is heated by cooling air taken from the compressor 2 and the cooling air is cooled. The water is then recovered into the inlet of the high pressure evaporator 18. By this arrangement, the heat as has so far been discharged outside in vain by the cooling fan is recovered into the waste heat recovery boiler 9 and the combined efficiency is enhanced.

[0092] FIG. 13 is a diagram of a steam cooled gas turbine system of a thirteenth embodiment according to the present invention. In the present thirteenth embodiment, as compared with the eighth embodiment shown in FIG. 8, the system is so made that saturated steam partially extracted from the outlet of the intermediate pressure economizer 12 is flown through the fuel heater 202 via the piping 201 for heating the fuel 7 and is then supplied to the inlet of the feed water heater 10 via the piping 203. By this arrangement, the fuel 7 is heated and the flow rate of the fuel is reduced. Thus, the gas turbine efficiency and the combined efficiency are enhanced.

[0093] Also, as compared with the eighth embodiment shown in FIG. 8, outlet water of the high pressure pump 27 is partially taken via the piping 204 to be supplied into the blade cooling air cooler 4. At the blade cooling air cooler 4, the water is heated by cooling air taken from the compressor 2 and the cooling air is cooled. The water is then recovered into the inlet of the high pressure evaporator 18. By this arrangement, the heat as has so far been discharged outside in vain by the cooling fan is recovered into the waste heat recovery boiler 9 and the combined efficiency is enhanced.

[0094] FIG. 14 is a diagram of a steam cooled gas turbine system of a fourteenth embodiment according to the present invention. In the present fourteenth embodiment, as compared with the ninth embodiment shown in FIG. 9, the system is so made that saturated steam partially extracted from the outlet of the intermediate pressure economizer 12 is flown through the fuel heater 202 via the piping 201 for heating the fuel 7 and is then supplied to the inlet of the feed water heater 10 via the piping 203. By this arrangement, the fuel 7 is heated and the flow rate of the fuel is reduced. Thus, the gas turbine efficiency and the combined efficiency are enhanced.

[0095] Also, as compared with the ninth embodiment shown in FIG. 9, outlet water of the high pressure pump 27 is partially taken via the piping 204 to be supplied into the blade cooling air cooler 4. At the blade cooling air cooler 4, the water is heated by cooling air taken from the compressor 2 and the cooling air is cooled. The water is then recovered into the inlet of the high pressure evaporator 18. By this arrangement, the heat as has so far been discharged outside in vain by the cooling fan is recovered into the waste heat recovery boiler 9 and the combined efficiency is enhanced.

[0096] FIG. 15 is a diagram of a steam cooled gas turbine system of a fifteenth embodiment according to the present invention. In the present fifteenth embodiment, as compared with the tenth embodiment shown in FIG. 10, the system is so made that saturated steam partially extracted from the outlet of the intermediate pressure economizer 12 is flown through the fuel heater 202 via the piping 201 for heating the fuel 7 and is then supplied to the inlet of the feed water heater 10 via the piping 203. By this arrangement, the fuel 7 is heated and the flow rate of the fuel is reduced. Thus, the gas turbine efficiency and the combined efficiency are enhanced.

[0097] Also, as compared with the tenth embodiment shown in FIG. 10, outlet water of the high pressure pump 27 is partially taken via the piping 204 to be supplied into the blade cooling air cooler 4. At the blade cooling air cooler 4, the water is heated by cooling air taken from the compressor 2 and the cooling air is cooled. The water is then recovered into the inlet of the high pressure evaporator 18. By this arrangement, the heat as has so far been discharged outside in vain by the cooling fan is recovered into the waste heat recovery boiler 9 and the combined efficiency is enhanced.

[0098] FIG. 16 is a diagram of a steam cooled gas turbine system of a sixteenth embodiment according to the present invention. In the present sixteenth embodiment, as compared with the first embodiment shown in FIG. 1, the system is so made that the heat exchanger 110, the piping 111 and the piping 112 which had been provided for cooling the moving blade cooling steam are eliminated and instead a water spray rate control valve 115, a demineralizer 118, a water sprayer 116 and a drain separator 114 are added for partially extracting outlet water of the high pressure pump 27 and controlling to spray the water for cooling the blade cooling steam.

[0099] By this arrangement, the water spray rate is controlled by the water spray rate control valve 115 and the supply temperature of the moving blade cooling steam becomes adjustable more quickly than in the first embodiment. However, in order to remove impurities in the water, it is necessary to provide such demineralizer 118 as is usually used for removing dissolved minerals in the condenser of a supercritical pressure plant or a nuclear plant. Also, as a small quantity of drain is generated after the water is sprayed by the water sprayer 116 into the blade cooling steam flowing through the piping 109, the drain separator 114 is provided for removing the drain of the steam.

[0100] Thus, a quicker reduction in the supply temperature and supply quantity of the moving blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0101] FIG. 17 is a diagram of a steam cooled gas turbine system of a seventeenth embodiment according to the present invention. In the present seventeenth embodiment, as compared with the second embodiment shown in FIG. 2, the system is so made, like in FIG. 16, that the heat exchanger 110, the piping 111 and the piping 112 are eliminated and instead the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are added for partially extracting outlet water of the high pressure pump 27 and controlling to spray the water for cooling the blade cooling steam. The function of the components so added is the same as that described with respect to FIG. 16 and description thereon is omitted.

[0102] By this arrangement, a reduction in the supply temperature and supply quantity of the moving blade and stationary blade cooling steam, which is quicker than in the second embodiment, becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0103] FIG. 18 is a diagram of a steam cooled gas turbine system of an eighteenth embodiment according to the present invention. In the present eighteenth embodiment, as compared with the third embodiment shown in FIG. 3, the system is so made, like in FIG. 16, that, instead of the heat exchanger 110, the piping 111 and the piping 112, the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are employed for partially extracting outlet water of the high pressure pump 27 and controlling to spray the water for cooling the blade cooling steam. The construction of other portions of the present embodiment is the same as that shown in FIG. 3. Also, the function of the components 114, 115, 116 and 118 so employed is the same as that described with respect to FIG. 16 and description thereon is omitted.

[0104] In the present eighteenth embodiment, a reduction in the supply temperature and supply quantity of the moving blade and stationary blade cooling steam as well as of the combustor transition piece cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, combustor transition piece, rotor and pipings can be ensured.

[0105] FIG. 19 is a diagram of a steam cooled gas turbine system of a nineteenth embodiment according to the present invention. In the present nineteenth embodiment, as compared with the fourth embodiment shown in FIG. 4, the system is so made, like in FIG. 16, that, instead of the heat exchanger 110, the piping 111 and the piping 112, the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are employed for partially extracting outlet water of the high pressure pump 27 and controlling to spray the water for cooling the blade cooling steam. The construction of other portions of the present embodiment is the same as that shown in FIG. 4. Also, the function of the components 114, 115, 116 and 118 so employed is the same as that described with respect to FIG. 16 and description thereon is omitted.

[0106] In the present nineteenth embodiment, a quicker reduction in the supply temperature and supply quantity of the moving blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0107] FIG. 20 is a diagram of a steam cooled gas turbine system of a twentieth embodiment according to the present invention. In the present twentieth embodiment, as compared with the fifth embodiment shown in FIG. 5, the system is so made, like in FIG. 16, that, instead of the heat exchanger 110, the piping 111 and the piping 112, the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are employed for partially extracting outlet water of the high pressure pump 27 and controlling to spray the water for cooling the blade cooling steam. The construction of other portions of the present embodiment is the same as that shown in FIG. 5. Also, the function of the components 114, 115, 116 and 118 so employed is the same as that described with respect to FIG. 16 and description thereon is omitted.

[0108] In the present twentieth embodiment, a quicker reduction in the supply temperature and supply quantity of the moving blade and stationary blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0109] FIG. 21 is a diagram of a steam cooled gas turbine system of a twenty-first embodiment according to the present invention. In the present twenty-first embodiment, as compared with the eleventh embodiment shown in FIG. 11, the system is so made that the heat exchanger 110, the piping 111 and the piping 112 which had been provided for cooling the moving blade cooling steam are eliminated and instead the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are added for partially extracting outlet water of the high pressure pump 27 and controlling to spray the water for cooling the blade cooling steam.

[0110] By this arrangement, the water spray rate is controlled by the water spray rate control valve 115 and the supply temperature of the moving blade cooling steam becomes adjustable more quickly than in the eleventh embodiment. However, in order to remove impurities in the water, it is necessary to provide such demineralizer 118 as is usually used for removing dissolved minerals in the condenser of a supercritical pressure plant or a nuclear plant. Also, as a small quantity of drain is generated after the water is sprayed by the water sprayer 116 into the blade cooling steam flowing through the piping 109, the drain separator 114 is provided for removing the drain of the steam.

[0111] Thus, a quicker reduction in the supply temperature and supply quantity of the moving blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0112] FIG. 22 is a diagram of a steam cooled gas turbine system of a twenty-second embodiment according to the present invention. In the present twenty-second embodiment, as compared with the twelfth embodiment shown in FIG. 12, the system is so made, like in FIG. 21, that, instead of the heat exchanger 110, the piping 111 and the piping 112, the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are employed for cooling the moving blade and stationary blade cooling steam. The function of the components so employed is the same as that described with respect to FIG. 21 and description thereon is omitted.

[0113] By this arrangement, a reduction in the supply temperature and supply quantity of the moving blade and stationary blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0114] FIG. 23 is a diagram of a steam cooled gas turbine system of a twenty-third embodiment according to the present invention. In the present twenty-third embodiment, as compared with the thirteenth embodiment shown in FIG. 13, the system is so made, like in FIG. 21, that, instead of the heat exchanger 110, the piping 111 and the piping 112, the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are employed. The construction of other portions of the present embodiment is the same as that shown in FIG. 13. Also, the function of the components 114, 115, 116 and 118 so employed is the same as that described with respect to FIG. 21 and description thereon is omitted.

[0115] In the present twenty-third embodiment, a reduction in the supply temperature and supply quantity of the moving blade and stationary blade cooling steam as well as of the combustor transition piece cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, combustor transition piece, rotor and pipings can be ensured.

[0116] FIG. 24 is a diagram of a steam cooled gas turbine system of a twenty-fourth embodiment according to the present invention. In the present twenty-fourth embodiment, as compared with the fourteenth embodiment shown in FIG. 14, the system is so made, like in FIG. 21, that, instead of the heat exchanger 110, the piping 111 and the piping 112, the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are employed. The construction of other portions of the present embodiment is the same as that shown in FIG. 14. Also, the function of the components 114, 115, 116 and 118 so employed is the same as that described with respect to FIG. 21 and description thereon is omitted.

[0117] In the present twenty-fourth embodiment, a quicker reduction in the supply temperature and supply quantity of the moving blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam. Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0118] FIG. 25 is a diagram of a steam cooled gas turbine system of a twenty-fifth embodiment according to the present invention In the present twenty-fifth embodiment, as compared with the fifteenth embodiment shown in FIG. 15, the system is so made, like in FIG. 21, that, instead of the heat exchanger 110, the piping 111 and the piping 112, the water spray rate control valve 115, the demineralizer 118, the water sprayer 116 and the drain separator 114 are employed. The construction of other portions of the present embodiment is the same as that shown in FIG. 15. Also, the function of the components 114, 115, 116 and 118 so employed is the same as that described with respect to FIG. 21 and description thereon is omitted.

[0119] In the present twenty-fifth embodiment, a quicker reduction in the supply temperature and supply quantity of the moving blade and stationary blade cooling steam becomes possible. Also, the temperature of the steam, after used for the cooling, can be controlled with less variation in the quantity of the cooling steam Hence, a spare quantity of the available steam is ensured and the reliability and life elongation of the cooled blade, rotor and pipings can be ensured.

[0120] It is to be noted that, in the mentioned embodiments, while a case where the cooling of the stationary blade only or the combustor transition piece only is done via the heat exchanger 110 or the water sprayer 116 has not been illustrated, such case is, needless to mention, possible and heated steam after used for the cooling in such case may be recovered into the waste heat recovery boiler 9.

[0121] Also, in the mentioned embodiments, while a case where the steam used for the cooling of the moving blade and stationary blade via the heat exchanger 110 or the water sprayer 116 is recovered into the waste heat recovery boiler 9 or a case where the steam used for the cooling of all the moving blade, stationary blade and combustor transition piece via the heat exchanger 110 or the water sprayer 116 is recovered into the waste heat recovery boiler 9 has not been illustrated, both of such cases are, needless to mention, possible and heated steam after used for the cooling in such cases may be recovered into the waste heat recovery boiler 9.

[0122] While preferred embodiments have been illustrated and described, it is to be understood that modifications thereof will be apparent to those skilled in the art without departing from the spirit of the invention. The scope of the invention, therefore, is to be determined solely by the appended claims.

Claims

1. A steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling a high temperature portion of the gas turbine including a high temperature portion of the combustor and a high temperature portion of a blade of the turbine; and a waste heat recovery boiler being fed with exhaust gas of the gas turbine so as to heat and vaporize condensed water coming from the condenser for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, wherein there is provided in the cooling steam system a heat exchanger for effecting a heat exchange so that outlet steam of the high pressure turbine flowing through the heat exchanger is cooled to be supplied into at least one of the high temperature portions of the gas turbine for cooling thereof and is then recovered into the waste heat recovery boiler and cooling water coming from the waste heat recovery boiler and flowing through the heat exchanger is heated and is then recovered into the waste heat recovery boiler.

2. A steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling a high temperature portion of the gas turbine including a high temperature portion of the combustor and a high temperature portion of a blade of the turbine; and a waste heat recovery boiler being fed with exhaust gas of the gas turbine so as to heat and vaporize condensed water coming from the condenser for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, wherein there are provided in the cooling steam system a water sprayer for leading a high pressure water from the waste heat recovery boiler via a demineralizer to be sprayed into a passage for leading cooling steam from an outlet of the high pressure turbine to be supplied into at least one of the high temperature portions of the gas turbine and a drain separator being interposed in a passage between the water sprayer and the at least one of the high temperature portions and the cooling steam of which drain has been removed by the drain separator is supplied into the at least one of the high temperature portions for cooling thereof and is then recovered into the waste heat recovery boiler.

3. A steam cooled gas turbine system as claimed in claim 1 or 2, wherein said high temperature portion of the gas turbine is a moving blade.

4. A steam cooled gas turbine system as claimed in claim 1 or 2, wherein said high temperature portion of the gas turbine is a stationary blade and the steam heated by cooling the stationary blade is recovered into the waste heat recovery boiler.

5. A steam cooled gas turbine system as claimed in claim 1 or 2, wherein said high temperature portion of the gas turbine is a combustor transition piece and the steam heated by cooling the combustor transition piece is recovered into the waste heat recovery boiler.

6. A steam cooled gas turbine system as claimed in claim 1 or 2, wherein said high temperature portion of the gas turbine is a moving blade and a stationary blade and the steam heated by cooling the stationary blade is recovered into the waste heat recovery boiler.

7. A steam cooled gas turbine system as claimed in claim 1 or 2, wherein said high temperature portion of the gas turbine is a moving blade, a stationary blade and a combustor transition piece and the steam heated by cooling the stationary blade and the combustor transition piece is recovered into the waste heat recovery boiler.

8. A steam cooled gas turbine system as claimed in claim 1 or 2, wherein said high temperature portion of the gas turbine is a stationary blade and a combustor transition piece and the steam heated by cooling the stationary blade and the combustor transition piece is recovered into the waste heat recovery boiler.

9. A steam cooled gas turbine system as claimed in any one of claims 1 to 8, wherein there is provided in the cooling steam system a flow regulating valve for regulating a flow rate of the steam so as to correspond to a cooling ability of the high temperature portion of the gas turbine.

10. A steam cooled gas turbine system as claimed in claim 9, wherein there is provided in a fuel inflow passage of the combustor of the gas turbine a fuel heater for heating fuel by steam coming from the waste heat recovery boiler and the steam cooled by heating the fuel is recovered into a feed water heater, and further wherein a portion of outlet water of the feed water heater is taken to flow through a blade cooling air cooler for cooling blade cooling air of the turbine and the water heated by cooling the blade cooling air is recovered into the waste heat recovery boiler.

11. A steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling the combustor and a blade of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a first high pressure economizer, a second high pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator, a reheater, etc. and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, wherein there is provided in the cooling steam system a heat exchanger for effecting a heat exchange so that outlet steam of the high pressure turbine flowing through the heat exchanger is cooled to be supplied into a moving blade of the gas turbine for cooling thereof and is then recovered into the reheater and cooling water coming from the first high pressure economizer and flowing through the heat exchanger is heated and is then recovered into the high pressure evaporator.

12. A steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling the combustor and a blade of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a first high pressure economizer, a second high pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator, a reheater, etc. and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, wherein there are provided in the cooling steam system a water spray rate control valve for leading a high pressure water from the feed water heater, a demineralizer being connected to the water spray rate control valve, a water sprayer being connected to the demineralizer for spraying the high pressure water into a passage for leading cooling steam from an outlet of the high pressure turbine to be supplied into a moving blade of the gas turbine and a drain separator being interposed in a passage between the water sprayer and the moving blade and the cooling steam of which drain has been removed by the drain separator is supplied into the moving blade for cooling thereof and is then recovered into the reheater.

13. A steam cooled gas turbine system comprising; a steam turbine having a high pressure turbine, an intermediate pressure turbine and a low pressure turbine; a condenser for condensing exhaust steam of the low pressure turbine of the steam turbine; a gas turbine having a compressor for compressing air, a combustor for combusting fuel with the air coming from the compressor and a turbine for expanding a high temperature combustion gas coming from the combustor for driving a generator; a cooling steam system for cooling the combustor and a blade of the turbine; and a waste heat recovery boiler having components of a feed water heater, an intermediate pressure economizer, a first high pressure economizer, a second high pressure economizer, a low pressure superheater, an intermediate pressure superheater, a high pressure superheater, a high pressure evaporator, a reheater, etc. and being fed with exhaust gas of the gas turbine so that condensed water coming from the condenser may be heated and vaporized via the components of the waste heat recovery boiler for supplying steam to the high pressure, intermediate pressure and low pressure turbines, respectively, wherein there are provided in the cooling steam system a water spray rate control valve for leading a high pressure water from the feed water heater, a demineralizer being connected to the water spray rate control valve, a water sprayer being connected to the demineralizer for spraying the high pressure water into a passage for leading cooling steam from an outlet of the high pressure turbine to be supplied into a moving blade of the gas turbine and a drain separator being interposed in a passage between the water sprayer and the moving blade and the cooling steam of which drain has been removed by the drain separator is supplied into the moving blade for cooling thereof and is then recovered into the reheater, and further wherein there are provided a heat exchanger side flow regulating valve near a steam inlet of the reheater in an outlet steam piping of the high pressure turbine connecting to the steam inlet of the reheater and an outflow side flow regulating valve in a cooling steam outlet passage of each of the moving blade, a stationary blade and a combustor transition piece, and still further wherein there is provided in a fuel inflow passage of the combustor a fuel heater for heating fuel by outlet steam of the intermediate pressure economizer and the steam cooled by heating the fuel is recovered into the feed water heater, and still further wherein a portion of outlet water of the feed water heater is taken to flow through a blade cooling air cooler for cooling blade cooling air of the turbine and the water heated by cooling the blade cooling air is recovered into the high pressure evaporator.