JP2000110509A - Combined cycle power plant - Google Patents

Abstract

(57) Abstract: Provided is a combined cycle power plant in which a gas turbine blade high-temperature section is effectively cooled by steam and energy efficiency is improved. A gas turbine 12, an exhaust heat recovery boiler,
And a steam turbine 13.
High pressure steam turbine 19 and second high pressure steam turbine 20
In the combined cycle power plant 11 including the medium-pressure steam turbine 21 and the low-pressure steam turbine 22, the exhaust steam of the first high-pressure steam turbine 19 is used as cooling steam for cooling the gas turbine blade high-temperature portion 24 of the gas turbine 12. A cooling steam supply pipe 25 for supplying, a cooling steam return pipe 25a for cooling the high temperature portion of the gas turbine blade to supply heated steam to the medium pressure steam turbine 21, a first high pressure steam turbine 19 and a second high pressure steam turbine 20, a pressure control valve 2 for controlling the pressure of the cooling steam.
7 was provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam-cooled combined cycle power plant for cooling a high temperature portion of a gas turbine blade of a gas turbine with steam, and in particular, to reduce a pressure loss due to a supply of cooling steam from a steam turbine. The present invention relates to a combined cycle power plant with improved energy efficiency.

[0002]

2. Description of the Related Art A combined cycle power plant is
It is a power plant that combines gas and steam turbines and has excellent performance and operability.Recently, with the increase in temperature and capacity of gas turbines, improvements have been made with the aim of further improving energy efficiency and increasing output. Is being done.

[0003] In this combined cycle power plant, it is known that the higher the gas turbine inlet temperature, the higher the output that can be obtained. However, when the gas turbine inlet temperature increases, a problem arises in the durability of the gas turbine blades arranged on the high temperature side.

Conventionally, air (hereinafter referred to as an air cooling system) has been used for cooling a high temperature portion of a gas turbine blade. However, at present, the gas turbine inlet temperature is about 1300 ° C.
And it is expected that the temperature will exceed 1500 ° C. and further exceed 1600 ° C. in the future. For this reason, in the conventional air cooling system, the required cooling air increases as the gas turbine inlet temperature increases, which causes a problem that the plant efficiency decreases.

Therefore, a steam cooling method of cooling a high temperature portion of a gas turbine blade using steam of a steam plant by utilizing the fact that steam has a higher specific heat than air has attracted attention. As the steam cooling method, for example, the paper 87-JPGC-GT-1 (ASME paper 87-JP)
GC-GT-1) "Closed circuit steam cooling of gas turbine (ClosedCir
cuit Steam Cooling in Gas Turbines). In this method, steam is extracted from the steam turbine system to cool the high temperature part of the gas turbine blades, and the steam heated by cooling is returned to the steam turbine system. However, in this closed circuit steam cooling system, the temperature and pressure requirements of the steam for cooling the gas turbine, the so-called heat recovery steam for cooling the gas turbine blades and returning. No consideration is given to the steam conditions between the heat recovery steam and the steam turbine system when the steam is returned to the steam turbine system.

FIG. 13 shows a combined cycle power plant for performing closed circuit steam cooling, for example. In the closed-cycle steam-cooled combined cycle power plant 1, the main steam superheated by the high-pressure superheater 2 is introduced into a reheat steam pipe 5 toward a reheater 4 after working in a high-pressure turbine 3. It has become. The reheat steam pipe 5 branches off from the cooling steam supply pipe 6 for cooling the high temperature part of the gas turbine blade before the reheater 4. To cool down. The cooling steam that has been superheated by cooling the gas turbine blade high-temperature section 7 joins the reheating steam pipe 5 again downstream of the reheater 4 via the cooling steam return pipe 8.

[0007]

However, in such steam cooling, the pressure loss of the cooling steam in the high temperature portion 7 of the gas turbine blade is large, so that the cooling steam branches off from the reheat steam supply pipe 5 and again flows through the reheat steam pipe 5. The pressure loss until merging is about 30% of the pressure immediately after branching. Therefore, considering the pressure loss of the steam flowing through the reheat steam pipe 5 at the reheater 4 and the pressure loss of the steam flowing through the cooling steam supply pipe 6 at the gas turbine high temperature section 7, It is necessary to reduce the pressure by about 20% by the pressure control valve 9 provided between the reheater 4 and the branch point of the cooling steam supply pipe 6, and it cannot be said that the energy efficiency is high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a combined power generation plant for cooling a gas turbine blade high-temperature section with steam in a gas turbine blade high-temperature section by relatively simple means. The present invention is to provide a combined cycle power plant that effectively cools, increases energy efficiency, increases output, and further improves operability.

[0009]

According to a first aspect of the present invention, there is provided a gas turbine, an exhaust heat recovery boiler, and a steam turbine. In a combined cycle power plant including a steam turbine, a second high-pressure steam turbine, a medium-pressure steam turbine, and a low-pressure steam turbine, the first high-pressure steam serves as cooling steam for cooling a high-temperature portion of a gas turbine blade of the gas turbine. A cooling steam supply pipe for supplying exhaust steam of the turbine, a cooling steam return pipe for cooling the high temperature portion of the gas turbine blade and supplying heated steam to the medium pressure steam turbine, the first high pressure steam turbine, And a pressure control valve provided between the second high-pressure steam turbine and adjusting a steam pressure of the cooling steam. To provide a plant.

[0010] In order to solve the above-mentioned problem, a second aspect is provided.
The invention according to claim 1, wherein the first high-pressure steam turbine, the second high-pressure steam turbine, the medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing. A combined cycle power plant.

[0011] In order to solve the above-mentioned problems, a third aspect of the present invention is provided.
The present invention provides the combined cycle power plant according to claim 1, wherein the gas turbine and the steam turbine are provided on different shafts.

[0012] In order to solve the above-mentioned problem, a fourth aspect of the present invention is provided.
The invention has a gas turbine, an exhaust heat recovery boiler, and a steam turbine, wherein the steam turbine is a combined cycle power plant including a high-pressure steam turbine, a medium-pressure steam turbine, and a low-pressure steam turbine. A cooling steam supply pipe for supplying steam extracted from the middle stage of the high-pressure steam turbine as cooling steam for cooling the gas turbine blade high-temperature portion of the gas turbine, and heating heated by cooling the gas turbine blade high-temperature portion A combined cycle comprising: a cooling steam return pipe for supplying steam to the medium-pressure steam turbine; and a pressure control valve provided in a path of the cooling steam supply pipe for adjusting a pressure of the cooling steam. Provide a power plant.

[0013] In order to solve the above-mentioned problems, a fifth aspect of the present invention is provided.
The present invention provides a combined cycle power plant according to claim 4, wherein the high-pressure steam turbine, the medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing.

[0014] In order to solve the above-mentioned problem, a sixth aspect of the present invention is provided.
The present invention provides a combined cycle power plant according to claim 4, wherein the gas turbine and the steam turbine are provided on different shafts.

[0015] In order to solve the above-mentioned problems, a seventh aspect of the present invention is provided.
The present invention has a gas turbine, an exhaust heat recovery boiler, and a steam turbine, and the steam turbine includes a high-pressure steam turbine, a mixed-pressure medium-pressure steam turbine, and a low-pressure steam turbine. A cooling steam supply pipe for supplying exhaust steam from the high-pressure steam turbine as cooling steam for cooling the gas turbine blade high-temperature section of the gas turbine; and heating steam heated by cooling the gas turbine blade high-temperature section. A cooling steam return pipe for supplying the cooling steam to the middle stage of the mixed-pressure medium-pressure steam turbine; and a pressure regulating valve provided in the middle of the cooling steam supply pipe for adjusting the pressure of the cooling steam. And a combined cycle power plant.

According to another aspect of the present invention, there is provided a computer system comprising:
The present invention provides the combined cycle power plant according to claim 7, wherein the high-pressure steam turbine, the mixed-pressure medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing. .

In order to solve the above-mentioned problem, a ninth aspect is provided.
The present invention provides a combined cycle power plant according to claim 7, wherein the gas turbine and the steam turbine are provided on different shafts.

[0018] In order to solve the above-mentioned problem, a first aspect of the present invention is provided.
The present invention provides a combined cycle power plant including a gas turbine, an exhaust heat recovery boiler, and a steam turbine, wherein the steam turbine includes a high-pressure steam turbine, a medium-pressure steam turbine, and a low-pressure steam turbine. A cooling steam supply pipe for supplying exhaust steam from the high-pressure steam turbine as cooling steam for cooling the gas turbine blade high-temperature portion of the gas turbine; and a heating steam heated by cooling the gas turbine blade high-temperature portion. Combined-cycle power generation, comprising: a cooling steam return pipe that supplies the cooling steam to the medium-pressure steam turbine; and a pressure control valve that is provided in the middle of the cooling steam supply pipe and that adjusts the pressure of the cooling steam. Provide a plant.

[0019] In order to solve the above-mentioned problems, a first aspect of the present invention is provided.
The invention according to claim 1 provides the combined cycle power plant according to claim 10, wherein the high-pressure steam turbine, the medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing.

[0020] In order to solve the above-mentioned problem, a first aspect of the present invention is provided.
A second invention provides the combined cycle power plant according to claim 10, wherein the gas turbine and the steam turbine are provided on different shafts.

[0021] In order to solve the above-mentioned problems, a first aspect of the present invention is described.
The invention according to claim 3 is characterized in that the steam pressure of the cooling steam return pipe is higher than the gas pressure of the turbine blade high-temperature section of the steam gas turbine. Provide a cycle power plant.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the combined cycle power plant according to the present invention will be described below with reference to the drawings.

First Embodiment (FIG. 1) FIG. 1 is a schematic system diagram showing a combined cycle power plant according to a first embodiment.

This combined cycle power plant 1
1 is a gas turbine 12 driven by the heat energy of the combustion gas, an exhaust heat recovery boiler (not shown) that generates superheated steam using the heat energy of the exhaust gas from the gas turbine 12, and A steam turbine 13 driven by thermal energy, and the gas turbine 12 and the steam turbine 13
7 for generating power. In the present embodiment, the gas turbine 12 and the steam turbine 13 are
1 shows a single-shaft combined cycle power plant connected by.

The gas turbine 12 is provided such that the air compressor 14 and the gas turbine blades 15 have a common axis.
A combustor (not shown) is provided between the air compressor 14 and the gas turbine blade 15. In this combustor, the air and fuel gas compressed by the air compressor 14 are mixed and burned, and the combustion gas expands the gas turbine blades 15 and rotates the gas turbine blades 15. ing.

The high-temperature exhaust gas that has completed the expansion work in the gas turbine blades 15 is guided to an exhaust heat recovery boiler (not shown). The exhaust heat recovery boiler includes at least a high-pressure superheater 16, a low-pressure superheater 17, and a reheater 18, and generates superheated steam by thermal energy of high-temperature exhaust gas from the gas turbine 12. I have.

On the other hand, the steam turbine 13 includes a first high-pressure steam turbine 19, a second high-pressure steam turbine 20, an intermediate-pressure steam turbine 21, and a low-pressure steam turbine 22, and is connected by a common rotor. It has become. And
The gas turbine blades 15 of the gas turbine 12 and the steam turbines 19, 20, 21, and 22 of the steam turbine 13 are interconnected by a single-shaft rotor 38, thereby forming a single-shaft combined cycle power plant 11. .

The superheated steam generated by the high-pressure superheater 16 is supplied to a first high-pressure steam turbine 19 via a first high-pressure steam pipe 23 to perform expansion work.
The steam that has completed the expansion work in the first high-pressure steam turbine 19 is converted into a second high-pressure steam pipe 26 that supplies steam to the second high-pressure steam turbine 20 and steam that cools the gas turbine blade high-temperature section 24 of the gas turbine 12. It is branched to a cooling steam supply pipe 25 to be supplied. A pressure control valve 27 that adjusts the pressure of steam supplied from the first high-pressure steam turbine is provided in the middle of the path of the second high-pressure steam pipe 26.

The steam introduced into the second high-pressure steam pipe 26 is adjusted in steam pressure by the pressure control valve 27 and supplied to the second high-pressure steam turbine 20 to perform expansion work. further,
The steam that has completed the expansion work in the second high-pressure steam turbine 20 is supplied to the reheater 18 via the reheat steam pipe 28, and is heated again by the reheater 18. The reheated steam is supplied to the medium-pressure steam turbine 21 via the reheat steam pipe 29.

On the other hand, the steam introduced into the cooling steam supply pipe 25 is guided by the gas turbine blade high temperature section 24 to perform cooling, and is heated by cooling the gas turbine blade high temperature section. The heated steam is returned to the cooling steam return pipe 25a.
Through the reheater 18 of the reheat steam pipe 29 through the reheat steam pipe 29.

The reheated steam reheated by the reheater 18 and the heated steam cooled by heating the gas turbine blade high temperature section 24 are combined and supplied to the medium-pressure steam turbine 21. The expansion work is performed again by the turbine 21.

The steam that has completed the expansion work in the medium-pressure steam turbine 21 is introduced into a low-pressure steam pipe 30. A pipe 31 for guiding the steam superheated by the low-pressure superheater 17 is connected in the middle of the low-pressure steam pipe 30, and the steam that has completed the expansion work in the medium-pressure steam turbine 21 and the low-pressure superheater 17 are superheated. The steam merges with the steam. The steam that has completed the expansion work in the medium-pressure steam turbine 21 and the steam that has been superheated in the low-pressure superheater 17 are supplied to the low-pressure steam turbine 22, and the low-pressure steam turbine 22 performs expansion work again.

The steam that has expanded by working in the low-pressure steam turbine 22 is supplied to a condenser 33 through a condenser pipe 32.
The steam is cooled and condensed by the condenser 33 to be condensed. The condensate in the condenser 33 is returned to the exhaust heat recovery boiler via the condensate water supply system 41 and turns into steam again.

In the figure, reference numeral 34 denotes the second high-pressure steam turbine 2
0 is a second high pressure steam turbine leak steam pipe that guides the leak steam from a shaft seal (not shown) provided to prevent the steam from leaking at 0 to the discharge side of the medium pressure turbine in order to work on the low pressure turbine again. Further, in the figure, reference numeral 35 denotes steam leaking from a gland seal provided for preventing steam from leaking from a casing (not shown) covering the steam turbines 19, 20, 21, 22 and the rotating rotor 38 to a condenser. This is the gland seal piping that leads. Further, reference numeral 36 denotes a second high-pressure steam turbine leaking steam pipe for guiding steam leaking from a shaft seal (not shown) to a condenser for preventing the steam from leaking in the medium-pressure steam turbine 21.

In the combined cycle power plant 11 according to the present embodiment, the fuel sent to the combustor (not shown) of the gas turbine 12 is mixed and burned with the air pressurized by the air compressor 14, and the combustion gas causes the gas turbine blades. 1
5 is rotated to generate power.

On the other hand, the exhaust gas expanded by the gas turbine blades 15 is guided to an exhaust heat recovery boiler, which exchanges heat with water supplied from the steam turbine 13 to generate steam. Released to the atmosphere.

The exhaust heat recovery boiler includes at least a high-pressure superheater 1
6, a reheater 18 and a low-pressure superheater 17, respectively, and the steam superheated or reheated by the high-pressure superheater 16, the reheater 18 and the low-pressure superheater 17 is supplied to the first high-pressure steam turbine 1.
9. Medium-pressure steam turbine 21 and low-pressure steam turbine 22
Are supplied to the steam turbines 19, 21 and 22, respectively.
Is rotated to generate power.

The steam discharged from the low-pressure steam turbine 22 is guided to a condenser 33 through a condensing pipe 32, is cooled and condensed, and is supplied to an exhaust heat recovery boiler to be converted into steam again.

This combined cycle power plant 1
1, the cooling of the gas turbine blade high-temperature section 24 is performed in the first mode.
This is performed by the steam that has completed the expansion work in the high-pressure steam turbine 19. That is, the steam that has completed the expansion work in the first high-pressure steam turbine 19 is branched into the second high-pressure steam pipe 26 and the cooling steam supply pipe 25. The steam introduced into the cooling steam supply pipe 25 is supplied as cooling steam to the gas turbine blade high temperature section 24 to cool the gas turbine blade high temperature section 24. The steam heated by cooling the gas turbine blade high temperature section 24 joins the reheat steam that has passed through the reheater 18 of the reheat steam pipe 29 via the cooling steam return pipe 25a.

On the other hand, the steam introduced into the second high-pressure steam pipe 26 is supplied to the second high-pressure steam turbine 20 after the pressure is adjusted by the pressure control valve 27, and performs expansion work again. The steam whose temperature has dropped due to this work is supplied to the reheater 18 through the reheat steam pipe 28, and is heated again by the reheater 18. The reheated steam merges with the heated steam from the cooling steam return pipe 25a to form the intermediate-pressure steam turbine 21.
Supplied to

The steam pressure of the cooling steam for cooling the gas turbine blade high-temperature section 24 is set to a steam pressure higher than the pressure of the combustion gas passing through the gas turbine blade 15. this is,
This is to prevent the combustion gas from entering the cooling steam return pipe 25a. Further, the steam pressure is adjusted by the pressure control valve 27, and the excess steam performs expansion work in the second high-pressure steam turbine 20, thereby eliminating waste of heat energy of the heated steam and improving energy efficiency.

According to the combined cycle power plant 11 of the present embodiment, the steam having a higher pressure than the pressure of the combustion gas supplied to the gas turbine blades 15 is guided from the first high-pressure steam turbine 19 and this steam is used as cooling steam. By doing so, the gas turbine blade high-temperature section 24 can be safely steam-cooled without the combustion gas entering the cooling steam return pipe 25a, and the combined cycle power plant 11
Can maintain soundness.

Further, in order to adjust the amount of cooling steam supplied to the gas turbine blade high temperature section 24, the first high-pressure steam turbine 1
The steam that has been worked in 9 is branched into cooling steam and steam to be introduced into the second high-pressure steam turbine 20, and one of them is expanded to work, thereby improving the energy efficiency of the steam turbine 13.

Further, the non-uniformity of the steam pressure due to the pressure loss in the high temperature section 24 of the cascade turbine blade can be positively eliminated by the bleeding control valve 27 at the junction of the steam return pipe 25a and the medium pressure steam pipe 29. By improving the energy efficiency of the steam turbine 13, the combined cycle power plant 1
1 can improve the energy efficiency.

Therefore, it is particularly suitable for use in a combined cycle power plant 11 having a gas turbine inlet temperature of 1500 ° C. class or higher. In addition, an excellent effect of improving the energy efficiency of the combined cycle power plant 11 is achieved.

Second Embodiment (FIG. 2) FIG. 2 is a schematic system diagram showing a combined cycle power plant according to a second embodiment.

In the combined cycle power plant 11A of this embodiment, each of the steam turbines 1
9, 20, 21 and 22 are formed in the same turbine casing 40.
This is different from the first embodiment in that it is provided inside. The other parts are substantially the same as those of the first embodiment shown in FIG.

According to the present embodiment, in addition to the same effects as in the first embodiment, the steam turbines 19, 20, 21, 21, and 22 are provided in the same turbine casing 40, so that An effect is obtained in that no coupling or the like is required between the 22 and the device configuration can be simplified.

Third Embodiment (FIG. 3) FIG. 3 is a schematic system diagram showing a combined cycle power plant according to a third embodiment.

The combined cycle power plant 11B according to the present embodiment is a multi-shaft combined cycle power plant in which the gas turbine 12 and the steam turbine 13 are provided on different shafts, and the generators 37a and 37b are respectively attached to the rotors 38a and 38b. Is provided. Other configurations are substantially the same as those of the first embodiment shown in FIG.

According to the present embodiment, in addition to the same effects as in the first embodiment, the gas turbine 12 and the steam turbine 13 are provided on the rotors 38a and 38b having different shafts. Can be started separately, and thermal stress can be easily monitored, etc.
The effect that drivability can be improved can be obtained.

Fourth Embodiment (FIG. 4) FIG. 4 is a schematic system diagram showing a combined cycle power plant according to a fourth embodiment.

The combined cycle power plant 11C according to the present embodiment is a three-pressure steam turbine 13b having a high-pressure steam turbine, a medium-pressure steam turbine, and a low-pressure steam turbine.

This combined cycle power plant 1
In 1C, a cooling steam supply pipe 25 is provided to supply cooling steam for cooling the high temperature portion of the gas turbine blades by extracting air from a middle stage of the high-pressure steam turbine 42, and a pressure regulating valve for adjusting the pressure of the cooling steam in the middle of the passage. 43 are provided.
Further, a reheat steam pipe 28 is provided from the last stage of the high-pressure steam turbine 42. Other configurations are substantially the same as those of the first embodiment shown in FIG.

In this embodiment, a cooling steam supply pipe 25 is provided from an intermediate stage of the high-pressure steam turbine 42 to extract cooling steam, and the gas turbine is controlled by a pressure control valve 43 provided in the middle of the cooling steam supply pipe 25. The cooling steam pressure is adjusted to be higher than the pressure of the combustion gas flowing into the high-temperature blade section 24, and is supplied to the high-temperature section 24 of the gas turbine so that the high-temperature section 24 of the gas turbine is effectively steam-cooled and the cooling steam return pipe The combustion gas is prevented from flowing into 25a.

According to this embodiment, in addition to the same effects as those of the first embodiment, the effect that the configuration of the apparatus is simplified because the high-pressure steam turbine 42 is used is obtained.

Fifth Embodiment (FIG. 5) FIG. 5 is a schematic system diagram of a combined cycle power plant according to a fifth embodiment. The combined cycle power plant 11D of the present embodiment is different from the fourth embodiment in that the steam turbines 42, 21, and 22 are provided in the same turbine casing 40. The other components are substantially the same as those of the fourth embodiment shown in FIG.

According to this embodiment, in addition to the same effects as in the fourth embodiment, since the steam turbines 42, 21, and 22 are provided in the same turbine casing 40, no coupling or the like is required, and the apparatus is not required. An effect that the configuration can be simplified can be obtained.

Sixth Embodiment (FIG. 6) FIG. 6 is a schematic system diagram of a combined cycle power plant according to a sixth embodiment. In the combined cycle power plant 11E of the present embodiment, the gas turbine 12
And a steam turbine 13 are provided on rotors 38a and 38b having different shafts, which is different from the fourth embodiment. The other components are substantially the same as those of the fourth embodiment shown in FIG.

According to the present embodiment, in addition to the same effects as in the fourth embodiment, the gas turbine 12 and the steam turbine 13 are provided on the rotors 38a and 38b having different shafts. Can be started separately, and thermal stress can be easily monitored, etc.
The effect that drivability can be improved can be obtained.

Seventh Embodiment (FIG. 7) FIG. 7 is a schematic system diagram of a combined cycle power plant according to a seventh embodiment.

In the combined cycle power plant 11F according to the present embodiment, the three-pressure steam turbine 13
, The mixed-pressure medium-pressure steam turbine 45 for introducing the heated steam after cooling the gas turbine blade high-temperature portion 24 to the middle stage of the turbine.
Are shown.

This combined cycle power plant 1
In 1F, the high-pressure steam turbine 46 is connected to the reheat steam pipe 28, and this reheat steam pipe 28 branches off the cooling steam supply pipe 25 having the pressure control valve 43 in the middle of the path.

The steam introduced into the cooling steam supply pipe 25 is adjusted to a pressure higher than the pressure of the combustion gas supplied to the gas turbine blades 15 by the pressure control valve 43, and is supplied to the gas turbine blade high temperature section 24 for cooling. Then, the heated steam heated by cooling is introduced into the middle stage of the mixed-pressure medium-pressure steam turbine 45 via the cooling steam return pipe 25a.

On the other hand, the steam in the reheat steam pipe 28 is supplied to the reheater 1
After being heated in 8, it is supplied to the mixed-pressure medium-pressure steam turbine 45. The other components are substantially the same as those of the fourth embodiment shown in FIG.

In the present embodiment, the steam in the cooling steam supply pipe 25 branched from the reheat steam pipe 28 is adjusted to a higher pressure than the combustion gas pressure supplied to the gas turbine blades 15 by the pressure control valve 43, Since the gas is supplied to the gas turbine blade high temperature section 24, the combustion gas is prevented from flowing into the cooling steam return pipe 25a.

According to this embodiment, in addition to the same effects as in the fourth embodiment, the reheat steam pipe 2 reheated by the reheater 18
8 is introduced into the first stage of the mixed-pressure medium-pressure steam turbine 45, while the steam of the cooling steam supply pipe 25 branched from the reheater 18 upstream of the reheat steam pipe 28 is supplied to the gas turbine blade high-temperature section. After the cooling of the cooling steam 24, the cooling steam return pipe 25
a, and is introduced into the middle stage of the mixed-pressure medium-pressure steam turbine 45, so that the steam heated by the reheater 18 and the steam heated when cooling the gas turbine blade high-temperature section 24 are efficiently separated. Available, combined cycle power plant 11F
The effect that the energy efficiency of this can be improved is acquired.

Eighth Embodiment (FIG. 8) FIG. 8 is a schematic system diagram of a combined cycle power plant according to an eighth embodiment. The combined cycle power plant 11 </ b> G of the present embodiment is different from the seventh embodiment in that the steam turbines 46, 45, 22 are provided in the same turbine casing 40. The other components are substantially the same as those of the seventh embodiment shown in FIG.

According to the present embodiment, in addition to the same effects as in the fourth embodiment, since the steam turbines 46, 45, and 22 are provided in the same turbine casing 40, no coupling or the like is required, and the apparatus is not required. An effect that the configuration can be simplified can be obtained.

Ninth Embodiment (FIG. 9) FIG. 9 is a schematic system diagram of a combined cycle power plant according to a ninth embodiment. In the combined cycle power plant 11H of the present embodiment, the gas turbine 12
This embodiment differs from the seventh embodiment in that it is a multi-shaft type in which the rotor and the steam turbine 13 are provided on rotors 38a and 38b having different shafts.
The other components are substantially the same as those of the seventh embodiment shown in FIG.

According to the present embodiment, in addition to the same effects as in the seventh embodiment, the gas turbine 12 and the steam turbine 13 are provided on the rotors 38a and 38b having different shafts to constitute a multi-shaft combined cycle power plant. Therefore, the gas turbine 12 and the steam turbine 13 can be started separately, and the monitoring of thermal stress can be easily performed, so that the effect of improving operability can be obtained.

Tenth Embodiment (FIG. 10) FIG. 10 is a schematic system diagram of a combined cycle power plant according to a tenth embodiment.

In the combined cycle power plant 11I according to this embodiment, a cooling steam supply pipe 25 having a pressure control valve 43 is provided in the middle of the path from the exhaust side of the high-pressure steam turbine 46, and the cooling steam supply pipe 25 is connected to the gas turbine blade high-temperature section. 24, and cools the gas turbine blade high temperature section 24. Further, a cooling steam return pipe 25a, which is a return flow path of heated steam heated by cooling the gas turbine blade high temperature section 24, is provided from the gas turbine blade high temperature section 24. The cooling steam return pipe 25a
Is introduced into the intermediate-pressure steam turbine 21. Figure 7 for others
Are substantially the same as those of the seventh embodiment shown in FIG.

This combined cycle power plant 1
In 1I, the steam that has completed the expansion work in the high-pressure steam turbine 46 is introduced into the cooling steam supply pipe 25, and the pressure of the cooling steam is supplied to the gas turbine 15 by the pressure regulating valve 43 provided in the middle of the cooling steam supply pipe. After the pressure is adjusted to a higher pressure than the supplied combustion gas pressure, it is supplied to the gas turbine blade high-temperature section 24 for cooling, and the heated steam heated by cooling is supplied through the cooling steam return pipe 25a. The steam is supplied to the high pressure steam turbine 21.

According to the present embodiment, in addition to the same effects as those of the first embodiment, there is obtained an effect that the apparatus configuration of the combined cycle power plant 11I can be simplified because no reheater is required.

Eleventh Embodiment (FIG. 11) FIG. 11 is a schematic system diagram of a combined cycle power plant according to an eleventh embodiment. The combined cycle power plant 11J of the present embodiment is different from the tenth embodiment in that the steam turbines 21, 22, and 46 are provided in the same turbine casing 40. The other components are substantially the same as those of the tenth embodiment shown in FIG.

According to the present embodiment, in addition to the same effects as in the tenth embodiment, since the steam turbines 21, 22, and 46 are provided in the same turbine casing, no coupling or the like is required, and the structure of the apparatus is reduced. Can be simplified.

Twelfth Embodiment (FIG. 12) FIG. 12 is a schematic system diagram of a combined cycle power plant according to a twelfth embodiment. In the combined-cycle power plant 11K of the present embodiment, the gas turbine 1
2 and the steam turbine 13 with rotors 38a, 38b having different shafts.
Is different from the tenth embodiment. The other components are substantially the same as those of the tenth embodiment shown in FIG.

According to the present embodiment, in addition to the same effects as in the tenth embodiment, the gas turbine 12 and the steam turbine 13
Are provided on separate shaft rotors 38a and 38b to form a multi-shaft combined cycle power plant, so that the gas turbine 12 and the steam turbine 13 can be started separately and thermal stress can be easily monitored. It is possible,
The effect is obtained that the operability of the combined cycle power plant 11K can be improved.

[0080]

As described above in detail, according to the combined cycle power plant of the present invention, the steam having a moderately higher pressure than the combustion gas pressure supplied from the steam turbine to the gas turbine is cooled by the steam turbine. As a result, the high temperature portion of the gas turbine blade can be cooled safely and effectively without the combustion gas entering the cooling steam supply pipe, and the soundness of the combined cycle power plant is maintained.

In addition, the excess steam generated when adjusting the pressure of the cooling steam supplied to the high temperature portion of the gas turbine blade is expanded by the steam turbine, thereby improving the energy efficiency of the steam turbine.

Further, since the unevenness of the steam pressure due to the pressure loss caused when passing through each steam pipe is positively eliminated and the pressure of the steam supplied to the steam turbine is effectively adjusted, the energy of the steam turbine is reduced. It is possible to improve the efficiency and thus the energy efficiency of the combined cycle plant.

Therefore, it is suitably used particularly in a combined cycle power plant having a gas turbine inlet temperature of 1500 ° C. class or higher, and appropriately cools a high temperature portion of a gas turbine blade by steam having a specific heat larger than that of air. In addition, an excellent effect of improving the plant efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic system diagram showing a first embodiment of a combined cycle power plant according to the present invention.

FIG. 2 is a schematic system diagram showing a second embodiment of a combined cycle power plant according to the present invention.

FIG. 3 is a schematic system diagram showing a third embodiment of the combined cycle power plant according to the present invention.

FIG. 4 is a schematic system diagram showing a fourth embodiment of the combined cycle power plant according to the present invention.

FIG. 5 is a schematic system diagram showing a fifth embodiment of the combined cycle power plant according to the present invention.

FIG. 6 is a schematic system diagram showing a sixth embodiment of the combined cycle power plant according to the present invention.

FIG. 7 is a schematic system diagram showing a seventh embodiment of the combined cycle power plant according to the present invention.

FIG. 8 is a schematic system diagram showing an eighth embodiment of a combined cycle power plant according to the present invention.

FIG. 9 is a schematic system diagram showing a ninth embodiment of a combined cycle power plant according to the present invention.

FIG. 10 is a schematic system diagram showing a tenth embodiment of a combined cycle power plant according to the present invention.

FIG. 11 is a schematic system diagram showing an eleventh embodiment of the combined cycle power plant according to the present invention.

FIG. 12 is a schematic system diagram showing a twelfth embodiment of the combined cycle power plant according to the present invention.

FIG. 13 is a schematic system diagram showing a conventional combined cycle power plant.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Combined cycle power plant 2 High pressure superheater 3 High pressure turbine 4 Reheater 5 Reheat steam pipe 6 Cooling steam supply pipe 7 Gas turbine blade high temperature section 8 Cooling steam return pipe 9 Pressure control valve 11, 11A, 11B, 11C, 11D , 11E, 11
F, 11G, 11H, 11I, 11J, 11K Combined cycle power plant 12 Gas turbine 13 Steam turbine 14 Air compressor 15 Gas turbine blade 16 High pressure superheater 17 Low pressure superheater 18 Reheater 19 First high pressure steam turbine 20 Second High-pressure steam turbine 21 Medium-pressure steam turbine 22 Low-pressure steam turbine 23 First high-pressure steam pipe 24 Gas turbine blade high-temperature section 25 Cooling steam supply pipe 25a Cooling steam return pipe 26 Second high-pressure steam pipe 27 Pressure control valve 28 Reheat steam pipe 29 Medium-pressure steam pipe 30 Low-pressure steam pipe 31 Pipe 32 Condensate pipe 33 Condenser 34 Second high-pressure steam turbine leak steam pipe 35 Ground seal pipe 36 Medium-pressure steam turbine ground seal pipe 37, 37a, 37b Generators 38, 38a, 38b rotor 40 turbine case Ring 41 condensate feed water system 42 high-pressure steam turbine 43 pressure regulating valve 45 in the mixed pressure steam turbine 46 high-pressure steam turbine

Claims (13)

[Claims] 1. A gas turbine, an exhaust heat recovery boiler, and a steam turbine, wherein the steam turbine is a first high-pressure steam turbine, a second high-pressure steam turbine, a medium-pressure steam turbine, and a low-pressure steam turbine. A cooling steam supply pipe for supplying exhaust steam of the first high-pressure steam turbine as cooling steam for cooling a high temperature portion of the gas turbine blades of the gas turbine, and a high temperature portion of the gas turbine blades. A cooling steam return pipe for supplying steam heated by cooling to the medium pressure steam turbine, and a cooling steam return pipe provided between the first high pressure steam turbine and the second high pressure steam turbine; A combined cycle power plant comprising a pressure control valve for adjusting. 2. The first high-pressure steam turbine and the second high-pressure steam turbine.
The combined cycle power plant according to claim 1, wherein the high-pressure steam turbine, the medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing. 3. The combined cycle power plant according to claim 1, wherein the gas turbine and the steam turbine are provided on different shafts. 4. A combined cycle power plant including a gas turbine, an exhaust heat recovery boiler, and a steam turbine, wherein the steam turbine includes a high-pressure steam turbine, a medium-pressure steam turbine, and a low-pressure steam turbine. A cooling steam supply pipe for supplying steam extracted from the middle stage of the high-pressure steam turbine as cooling steam for cooling the gas turbine blade high-temperature portion of the gas turbine, and the gas turbine blade high-temperature portion was cooled and heated. A combination comprising: a cooling steam return pipe for supplying heated steam to the medium-pressure steam turbine; and a pressure control valve provided in the course of the cooling steam supply pipe for adjusting the pressure of the cooling steam. Cycle power plant. 5. The combined cycle power plant according to claim 4, wherein the high-pressure steam turbine, the medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing. 6. The combined cycle power plant according to claim 4, wherein the gas turbine and the steam turbine are provided on different shafts. 7. A combined cycle power generator having a gas turbine, an exhaust heat recovery boiler, and a steam turbine, wherein the steam turbine includes a high-pressure steam turbine, a mixed-pressure medium-pressure steam turbine, and a low-pressure steam turbine. A cooling steam supply pipe for supplying exhaust steam from the high-pressure steam turbine as cooling steam for cooling a gas turbine blade high-temperature portion of the gas turbine, and a heated steam heated by cooling the gas turbine blade high-temperature portion; A cooling steam return pipe that supplies the cooling steam to the middle stage of the mixed-pressure medium-pressure steam turbine, and a pressure control valve that is provided in the middle of the cooling steam supply pipe and adjusts the pressure of the cooling steam. Features a combined cycle power plant. 8. The combined cycle power plant according to claim 7, wherein the high-pressure steam turbine, the mixed-pressure medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing. 9. The combined cycle power plant according to claim 7, wherein the gas turbine and the steam turbine are provided on different shafts. 10. A gas turbine, an exhaust heat recovery boiler,
Having a steam turbine, the steam turbine is a combined cycle power plant comprising a high-pressure steam turbine, a medium-pressure steam turbine, and a low-pressure steam turbine,
A cooling steam supply pipe for supplying exhaust steam from the high-pressure steam turbine as cooling steam for cooling the gas turbine blade high-temperature portion of the gas turbine, and heating steam heated by cooling the gas turbine blade high-temperature portion, A combined cycle power plant comprising: a cooling steam return pipe to be supplied to a pressurized steam turbine; and a pressure control valve provided in the course of the cooling steam supply pipe to adjust the pressure of the cooling steam. 11. The combined cycle power plant according to claim 10, wherein the high-pressure steam turbine, the medium-pressure steam turbine, and the low-pressure steam turbine are provided in the same turbine casing. 12. The combined cycle power plant according to claim 10, wherein said gas turbine and said steam turbine are provided on different shafts. 13. The combination according to claim 1, wherein a steam pressure of the cooling steam return pipe is higher than a gas pressure of a high temperature portion of a turbine blade of the steam gas turbine. Cycle power plant.