Combined thermal power generation system using feed water heater

Abstract

To provide a combined thermal power generation system capable of increasing efficiency of a bottoming cycle by arranging a feed water heater in a combined thermal power plant to which super critical and ultra super critical main steam pressure is applied, and applying a regenerative cycle.SOLUTION: A combined thermal power generation system using a feed water heater includes: a gas turbine for generating electric energy by mixing air and fuel and burning the mixture; an exhaust heat recovery boiler for discharging steam generated by exchanging heat with gas turbine exhaust gas discharged from the gas turbine and water; a steam turbine supplied with the steam discharged from the exhaust heat recovery boiler for generating electricity; a steam condenser for condensing the steam discharged from the steam turbine; and a low pressure feed water heater for increasing thermal efficiency by sending condensed water generated by recovering extraction steam generated from the steam turbine and exchanging heat to the steam condenser.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a combined cycle power generation system, and more particularly to a combined cycle power generation system using a feed water heater. [Background technology]

[0002] In general, combined cycle power generation is a system that generates electricity by combining a gas turbine generator and a steam turbine generator. Combined cycle power generation primarily uses the heat generated by burning fuel in the gas turbine, and then reuses it in a heat recovery boiler, thereby increasing the efficiency of energy usage.

[0003] In a conventional combined cycle power generation system, air is injected through a compressor and fuel is injected into a combustion device to burn the fuel. The high-temperature flue gas generated by the combustion of the fuel rotates a gas turbine, and electricity is primarily generated by the first generator. Then, to utilize the heat remaining in the exhaust gas, the exhaust gas is injected into a heat recovery steam generator (HRSG), and water is heated in the boiler heat exchanger of the HRSG to produce high-temperature, high-pressure steam. The high-temperature, high-pressure steam rotates a steam turbine, and electricity is secondarily generated by the second generator. At this time, the steam after rotating the steam turbine is cooled and condensed by a condenser, and the condensed water is supplied again to the HRSG by a condensate pump.

[0004] However, in the conventional combined cycle power generation system, although the efficiency of combustion heat can be improved, a large amount of heat loss occurs due to the warm waste heat generated in the condenser and the residual heat of the exhaust gas generated in the heat recovery boiler during the process of condensing the steam into water. If such waste heat and residual heat are not recovered, the efficiency of the entire power plant will decrease and a large amount of cooling water will be consumed for cooling. Summary of the Invention [Problem to be solved by the invention]

[0005] The technical problem to be solved by the present invention is to provide a combined cycle power generation system that can increase the efficiency of a bottoming cycle by arranging a feed water heater in a combined cycle power plant to which supercritical and ultra-supercritical main steam pressures are applied and applying a regenerative cycle, thereby reducing the equipment costs of the power plant by the increased efficiency.

[0006] The technical problems that the present invention aims to solve are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the art to which the present invention pertains from the following description. [Means for solving the problem]

[0007] In order to achieve the above technical objectives, one embodiment of the present invention provides a combined cycle power generation system using a feed water heater, the combined cycle power generation system including a gas turbine that generates electric energy by mixing air and fuel and burning the mixture, a heat recovery steam generator (HRSG) that exchanges heat with gas turbine exhaust gas discharged from the gas turbine and discharges the generated steam and water, a steam turbine that generates electricity by being supplied with the steam discharged from the heat recovery steam generator, a condenser that condenses the steam discharged from the steam turbine, and a low pressure feed water heater that increases thermal efficiency by sending condensed water generated by recovering extraction steam generated from the steam turbine and exchanging it with heat to the condenser.

[0008] In an embodiment of the present invention, the combined cycle power generation system may be used in a combined cycle power plant to which supercritical or ultra-supercritical main steam pressure is applied.

[0009] In an embodiment of the present invention, the steam turbine comprises a high-pressure turbine driven by steam having a first pressure range, an intermediate-pressure turbine driven by steam having a second pressure range, and a low-pressure turbine driven by steam having a third pressure range, and the condenser may be connected to the low-pressure turbine and supplied with steam discharged from the low-pressure turbine.

[0010] In an embodiment of the present invention, the combined cycle power generation system may further include a medium-pressure feedwater heater that extracts steam discharged from the steam turbine and performs heat exchange between the extracted steam and water supplied from the condenser, thereby generating condensed water, which is transmitted to the low-pressure feedwater heater side.

[0011] In an embodiment of the present invention, the combined cycle power generation system further includes an intermediate pressure feedwater pump that supplies water supplied from the condenser to the intermediate pressure feedwater heater, and the intermediate pressure feedwater heater may include a second intermediate pressure feedwater heater that performs heat exchange using steam discharged from the high pressure turbine and water supplied from the intermediate pressure feedwater pump, and a first intermediate pressure feedwater heater that performs heat exchange using steam discharged from the intermediate pressure turbine and water supplied from the intermediate pressure feedwater pump.

[0012] In an embodiment of the present invention, condensed water discharged by heat exchange in the first intermediate-pressure feedwater heater and the second intermediate-pressure feedwater heater may be recovered to the low-pressure feedwater heater side.

[0013] In an embodiment of the present invention, condensed water discharged from the condenser may be branched and fed to the medium pressure feed water heater and a condensate preheater side of the heat recovery boiler.

[0014] In an embodiment of the present invention, the heat recovery boiler may include a high-pressure superheater that discharges steam in a first pressure range generated by heat exchange with gas turbine exhaust gas discharged from the gas turbine to the steam turbine, a high-pressure once-through evaporator that heat exchanges water supplied thereto to convert it into steam and sends the converted steam to the high-pressure superheater, a medium-pressure evaporator connected to the medium-pressure feedwater heater and receives water from the medium-pressure feedwater heater and exchanges heat with it to generate steam in a second pressure range, a reheater connected to the steam turbine and discharges steam to the steam turbine, a low-pressure superheater that discharges steam in a third pressure range generated by heat exchange with exhaust gas from the gas turbine to the steam turbine, a condensate preheater that heats water condensed in the condenser, and a low-pressure evaporator that heat exchanges water supplied from the condensate preheater to convert it into steam and sends the converted steam to the low-pressure superheater.

[0015] In an embodiment of the present invention, the condensate preheater may be connected to the low pressure feed water heater and may be supplied with water to be heated and driven.

[0016] In an embodiment of the present invention, a plurality of the low pressure feed water heaters may be provided. Effect of the Invention

[0017] According to an embodiment of the present invention, by installing a feedwater heater in a combined cycle power plant to which supercritical main steam pressure or ultra-supercritical main steam pressure is applied and applying a regenerative cycle, it is possible to increase the efficiency of the bottoming cycle and reduce the equipment costs of the power plant by the amount of the increased efficiency.

[0018] The effects of the present invention are not limited to the effects described above, but should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the present invention or the claims. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a circuit diagram for explaining an operation method of a conventional combined cycle power plant. [Diagram 2] 1 is a circuit diagram showing a schematic configuration of a combined cycle power generation system using a feedwater heater according to an embodiment of the present invention. [Diagram 3] FIG. 11 is a circuit diagram showing a schematic configuration of a combined cycle power generation system using a feedwater heater according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. In the drawings, parts that are not relevant to the description are omitted in order to clearly explain the present invention, and the same reference numerals are used throughout the specification to refer to the same or similar components.

[0021] Throughout the specification, when a part is said to be "connected (connected, contacted, coupled)" to another part, this includes not only the case where the part is "directly connected" to another part, but also the case where the part is "indirectly connected" to another part via another element therebetween. Throughout the specification, when a part is said to "include" a certain component, this does not exclude other components, and means that the part may further include other components, unless otherwise specified.

[0022] The terms used in this application are merely used to describe certain embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this specification, the terms "include" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and are understood not to preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0024] FIG. 1 is a circuit diagram shown for explaining an operation method of a conventional combined cycle power plant.

[0025] Referring to FIG. 1, the operation method of a conventional cogeneration plant will be described. First, atmospheric air and natural gas (fuel) flow into a gas turbine, where the air and fuel are combusted to drive a generator and generate electricity.

[0026] The inflowing air and fuel are combusted in the gas turbine, and exhaust gas is discharged. The exhaust gas thus discharged flows into a heat recovery steam generator (HRSG).

[0027] Exhaust gas is supplied to each heat exchanger while passing through multiple heat exchangers installed in the heat recovery steam generator. The heat recovery steam generator uses the heat absorbed by each heat exchanger to raise the temperature of water, generate steam, and increase the temperature of the steam. The steam with increased temperature and pressure drives a steam turbine to generate steam, and after the steam turbine is driven, the steam is supplied to a condenser for regeneration and condensed, as there is a shortage of energy to drive the steam turbine. The condensate condensed in the condenser is sent back to the heat recovery steam generator (HRSG) and used to generate steam.

[0028] As described above, in the conventional combined cycle power generation system, the efficiency of using the heat of combustion can be improved, but in the process of cooling the steam with water, a large amount of heat loss occurs due to the waste heat of the warm wastewater generated in the condenser and the residual heat of the exhaust gas generated in the heat recovery boiler. If such waste heat and residual heat are not recovered, there is a problem that the efficiency of the entire power plant decreases and a large amount of cooling water is consumed for cooling.

[0029] The present invention relates to a combined cycle power generation system, and more particularly to a combined cycle power generation system using a feed water heater for solving the above-mentioned problems of the conventional technology.

[0030] FIG. 2 is a circuit diagram that shows a schematic configuration of a combined cycle power generation system using the feedwater heater according to one embodiment of the present invention.

[0031] The combined cycle power plant according to an embodiment of the present invention is a system used in a combined cycle power plant to which a supercritical 220 bar main steam pressure or an ultra-supercritical 240 bar main steam pressure is applied. The combined cycle power plant according to the present invention can increase the efficiency of the bottoming cycle by applying a regenerative cycle using a feedwater heater, and can reduce the cost of power plant equipment by the increased efficiency.

[0032] Specifically, as the main steam pressure for application to an ultra-supercritical pressure combined cycle power plant increases, the thickness of the heat exchanger tubes on the high pressure (HP) side of the HRSG becomes thicker, and in recent years, raw material costs have been rising. Due to such rising raw material costs, it is becoming difficult to build highly efficient supercritical or ultra-supercritical pressure combined cycle power plants in many places. In order to solve this problem, the present invention has the advantage of increasing the efficiency of the bottoming cycle by applying a feedwater heater, thereby reducing equipment costs by the amount of increased efficiency. Here, the bottoming cycle is a typical Rankine cycle consisting of a boiler and a steam turbine.

[0033] Referring to FIG. 2, air and fuel are mixed and fed to a gas turbine 100 to produce electrical energy and produce gas turbine exhaust gases.

[0034] The gas turbine 100 compresses atmospheric air, mixes it with fuel using a combustor, and generates combustion gas through a combustion process. The combustion gas thus generated expands while driving the blades of the gas turbine 100, at which time thermal energy is converted into rotational energy, and the rotational energy is converted into electrical energy to generate electricity.

[0035] The exhaust gas from the gas turbine flows into the heat recovery steam generator 300, which exchanges heat with the exhaust gas from the gas turbine to produce steam and increase the temperature of the steam. The steam generated in this process can be used to generate electricity, and the water generated in this process can be used to increase the temperature of the steam.

[0036] The heat recovery steam generator 300 uses high-temperature exhaust gas flowing in from the gas turbine 100 to increase the temperature of water (condensate), produces steam, and provides the steam with a degree of superheat (temperature increase) to supply the steam to the steam turbine 500.

[0037] A heat recovery steam generator 300 according to an embodiment of the present invention may be configured with a plurality of superheaters, evaporators, and economizers, as shown in FIG.

[0038] The heat recovery boiler 300 according to this embodiment may include a second reheater 310, a second high-pressure superheater 320, a first reheater 330, a first high-pressure superheater 340, a high-pressure once-through evaporator 350, an intermediate pressure superheater 360, a second high-pressure economizer 370, an intermediate pressure evaporator 380, an intermediate pressure drum 390, a first valve 400, a low-pressure superheater 410, a first high-pressure economizer 420, a low-pressure evaporator 430, a low-pressure drum 440, a high-pressure feedwater pump 450, a second valve 460, and a condensate preheater 470.

[0039] The second high pressure superheater 320 sends high temperature steam in a first pressure range, which is generated by heat exchange using the gas turbine exhaust gas discharged from the gas turbine 100, to the steam turbine 500 via the main steam piping 210. The first high pressure superheater 340 increases the temperature of the steam generated from the high pressure once-through evaporator 350, and then the steam with the increased temperature is supplied to the high pressure turbine 510 via the second high pressure superheater 320 and the main steam piping 210.

[0040] The high-pressure once-through evaporator 350 exchanges heat with the water sent from the second high-pressure economizer 370 to convert it into steam, and the steam thus converted is sent to the high-pressure superheater 340 .

[0041] The first high-pressure coal cutter 420 heats the water sent from the low-pressure drum 440 and sends it to the second high-pressure coal cutter 370.

[0042] The steam generated in the intermediate pressure evaporator 380 passes through the intermediate pressure superheater 360 where its temperature is primarily increased, and the steam whose temperature has been primarily increased passes through the first reheater 330 and flows into the second reheater 310 where its temperature is secondarily increased, and is then supplied to the intermediate pressure turbine 530 through the high temperature reheat steam piping 220.

[0043] The medium-pressure evaporator 380 is connected to the medium-pressure feed water heater 900, and generates steam in the second pressure range by heat exchange with water sent from the medium-pressure feed water heater 900. At this time, the generated steam is sent to the medium-pressure superheater 360 via the medium-pressure drum 390.

[0044] The low-pressure evaporator 430 converts the water delivered from the condensate preheater 470 into steam in a third pressure range and sends it to the low-pressure superheater 410 via the low-pressure drum 440. The steam with increased temperature is then supplied to the low-pressure turbine 550 via the low-pressure steam piping 240.

[0045] The water pumped through the low-pressure drum 440 is then sent to the first high-pressure coal cutter 420 via the high-pressure water supply pump 450.

[0046] The condensate preheater 470 receives and heats the water condensed in the condenser 700. For example, the condensate preheater 470 according to the embodiment of the present invention can heat the water (condensed water) of 20°C to 30°C condensed in the condenser 700 to 150°C. The condensate preheater of the present invention has substantially the same configuration as a low-pressure coal chopper.

[0047] At this time, the condensate preheater 470 is connected to the low pressure feed water heater 800 and can be supplied with water to be driven for heating.

[0048] The high-pressure feed water pump 450 can send the water whose temperature has been increased in the condensate preheater 470 to the high-pressure once-through evaporator 350 of the heat recovery steam generator 300 .

[0049] The steam turbine 500 can generate electricity by being supplied with steam discharged from the heat recovery steam generator 300. In the steam turbine 500, high-temperature and high-pressure steam generated in a steam generator such as a nuclear reactor, a boiler, or a heat recovery steam generator (HRSG) drives blades inside the turbine, causing an expansion process, and the thermal energy is converted into rotational energy, which is then converted into electrical energy to generate electricity.

[0050] A steam turbine 500 according to an embodiment of the present invention may be configured with a high-pressure turbine 510 driven using steam having a first pressure range, an intermediate-pressure turbine 530 driven using steam having a second pressure range, and a low-pressure turbine 550 driven using steam having a third pressure range.

[0051] More specifically, a generator 600 may be provided in communication with the steam turbine 500 for generating electricity using the rotational energy.

[0052] The condenser 700 condenses the steam discharged from the steam turbine 500 and forms a vacuum due to a density difference during the condensation process, thereby increasing the output and efficiency of the steam turbine 500.

[0053] In the present invention, the condenser 700 is connected to the low-pressure turbine 550 as shown in FIG. 2, and can be supplied with low-pressure steam discharged from the low-pressure turbine 550.

[0054] The low-pressure feed water heater 800 is connected to the low-pressure turbine 550 and the condenser 700, thereby recovering the extraction steam generated from the steam turbine 500 and exchanging heat therewith, and sending the condensed water generated to the condenser 700 to increase thermal efficiency.

[0055] In conventional condensers, 50% of the total energy was lost as waste heat, but the low-pressure feedwater heater of the present invention can recover and reuse part of the energy, thereby significantly reducing the proportion of heat wasted from the condenser to outside the power plant.

[0056] The condensate pump 710 serves to send the water condensed in the condenser 700 to the heat recovery steam generator 300 .

[0057] The intermediate-pressure feedwater heater 900 is supplied with steam extracted from the steam turbine 500, and performs heat exchange between the extracted steam and water supplied from the condenser 700, thereby enabling condensed water generated in the intermediate-pressure feedwater heater 900 to be recovered in the low-pressure feedwater heater 800. The intermediate-pressure feedwater heater 900 according to this embodiment can extract steam from each of the high-pressure turbine 510 and the intermediate-pressure turbine 530.

[0058] The medium-pressure feedwater heater 900 may be disposed on a pipe extending from the condensate system toward the medium-pressure evaporator 380 as shown in FIG.

[0059] The medium pressure feedwater pump 950 can supply water supplied from the condenser 700 to the medium pressure feedwater heater 900 .

[0060] A medium pressure feedwater heater 900 according to an embodiment of the present invention may be configured to include a second medium pressure feedwater heater 910 and a first medium pressure feedwater heater 930.

[0061] The second intermediate-pressure feedwater heater 910 extracts high-pressure steam from the high-pressure turbine 510 and exchanges heat with water supplied from the intermediate-pressure feedwater pump 950 .

[0062] The first intermediate-pressure feedwater heater 930 extracts intermediate-pressure steam from the intermediate-pressure turbine 530 and exchanges heat with water supplied from the intermediate-pressure feedwater pump 950 .

[0063] The condensed water discharged from the condenser 700 is branched and sent to the intermediate pressure feed water heaters 910 and 930 side and the condensate preheater 470 side of the heat recovery boiler 300 .

[0064] 3 is a circuit diagram showing a schematic configuration of a combined cycle power generation system using a feedwater heater according to another embodiment of the present invention. In the combined cycle power generation system according to this embodiment, the low-pressure feedwater heater 800 may be configured to include a second low-pressure feedwater heater 810 and a first low-pressure feedwater heater 830.

[0065] The second low pressure feed water heater 810 and the first low pressure feed water heater 830 are each connected to the low pressure turbine 550, and can recover the extracted steam generated from the low pressure turbine 550 and exchange heat therewith.

[0066] As described above, the combined cycle power generation system of the present invention is composed of a combination of two gas turbines, two heat recovery boilers, and one steam turbine (2:2:1 combination), and by arranging the low pressure feedwater heater 800, the first intermediate pressure feedwater heater 930, and the second intermediate pressure feedwater heater 910 on the combined cycle power generation system, the following advantages are obtained.

[0067] First, it is economical because it allows the heat exchange area of ​​the existing condensate preheater to be reduced.

[0068] Secondly, by providing the feedwater heater, it is no longer necessary to use a separate intermediate pressure economizer (IP economizer) that was previously used in conventional heat recovery boilers, which reduces the cost of constructing the HRSG.

[0069] Thirdly, the heat exchangers of heat recovery steam generators (HRSGs) are installed on top of each HRSG, but the feedwater heater of the present invention can be installed at 100% capacity in each building in which the steam turbine is installed, thereby reducing installation costs.

[0070] Fourth, the combined cycle power generation system of the present invention can form a regenerative cycle by providing a feed water heater, so that the amount of condensed water is reduced compared to conventional power generation systems, and accordingly the heat exchange area of ​​the condenser and the amount of piping can be reduced.

[0071] Fifth, it is possible to prevent corrosion of the condensate preheater due to an increase in the exhaust gas outlet temperature of the heat recovery steam generator (HRSG), and it is possible to omit the bypass pump and recirculation pump of the heat recovery steam generator that were installed in conventional combined cycle power plants.

[0072] Sixthly, according to the present invention, in the case of medium-pressure feed water, since the water is immediately sent to the medium-pressure heat exchanger of the heat recovery boiler, there is an advantage that the amount of water in the low-pressure drum can be reduced.

[0073] The above description of the present invention is for illustrative purposes only, and a person having ordinary skill in the art to which the present invention pertains can easily understand that the present invention can be easily modified into other specific forms without changing the technical idea or essential features of the present invention. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, each component described as a distributed type may be implemented in a combined form within the scope of understanding of a person skilled in the art.

[0074] The scope of the present invention is defined by the claims set forth below, and all modifications and variations that come within the meaning and scope of the claims and their equivalents are included within the scope of the present invention. [Explanation of symbols]

[0075] 100 Gas Turbine 300 Waste heat recovery boiler 450 High Pressure Water Pump 470 Condensate preheater 500 Steam Turbine 600 Generator 700 Condenser 800 Low pressure feed water heater 900 Medium pressure feed water heater 950 Medium pressure water pump

Claims

1. A combined cycle power generation system using a feed water heater, a gas turbine that generates electrical energy by mixing and burning air and fuel; a heat recovery steam generator (HRSG) that exchanges heat with gas turbine exhaust gas discharged from the gas turbine and discharges steam and water generated therefrom; a steam turbine that generates electricity by being supplied with steam discharged from the heat recovery boiler; a condenser for condensing steam discharged from the steam turbine; and a low-pressure feed water heater that recovers extraction steam generated from the steam turbine and exchanges heat therewith to send condensed water generated therefrom to the condenser, thereby increasing thermal efficiency. A combined cycle power generation system comprising:

2. The combined cycle power generation system comprises: Used in combined cycle power plants where super critical or ultra-super critical main steam pressure is applied The combined cycle power generation system according to claim 1 .

3. The steam turbine includes: a high pressure turbine driven with steam having a first pressure range; an intermediate pressure turbine driven with steam having a second pressure range; a low pressure turbine driven with steam having a third pressure range; The condenser is connected to the low-pressure turbine and is supplied with steam discharged from the low-pressure turbine. The combined cycle power generation system according to claim 1 .

4. The steam turbine is cooled by a high-pressure steam condenser, and the steam is cooled by a high-pressure steam condenser. The combined cycle power generation system according to claim 3 .

5. a medium-pressure feed water pump that supplies water supplied from the condenser to the medium-pressure feed water heater, The medium pressure feed water heater comprises: a second intermediate pressure feed water heater that exchanges heat between the steam discharged from the high pressure turbine and the water supplied from the intermediate pressure feed water pump; a first intermediate-pressure feed water heater that exchanges heat between the steam discharged from the intermediate-pressure turbine and the water supplied from the intermediate-pressure feed water pump. The combined cycle power generation system according to claim 4.

6. Condensed water discharged from the first intermediate pressure feed water heater and the second intermediate pressure feed water heater through heat exchange is recovered to the low pressure feed water heater side. The combined cycle power generation system according to claim 5.

7. Condensed water discharged from the condenser is branched and sent to the medium pressure feed water heater and the condensate preheater of the heat recovery boiler. The combined cycle power generation system according to claim 4.

8. The heat recovery boiler comprises: a high pressure superheater that discharges steam having a first pressure range generated by heat exchange with gas turbine exhaust gas discharged from the gas turbine to the steam turbine; a high-pressure once-through evaporator that converts the supplied water into steam by heat exchange and sends the converted steam to the high-pressure superheater; a medium pressure evaporator connected to the medium pressure feed water heater and configured to receive water from the medium pressure feed water heater and perform heat exchange to generate steam in a second pressure range; a reheater coupled to the steam turbine and configured to discharge steam to the steam turbine; a low pressure superheater that discharges steam having a third pressure range generated by heat exchange with exhaust gas from the gas turbine to the steam turbine; A condensate preheater that heats the water condensed in the condenser; a low-pressure evaporator that converts the water supplied from the condensate preheater into steam by heat exchange and sends the converted steam to the low-pressure superheater. The combined cycle power generation system according to claim 4.

9. The condensate preheater is It is connected to the low pressure water heater and is supplied with water to heat it. The combined cycle power generation system according to claim 8.

10. The low pressure feed water heater is provided in plurality. The combined cycle power generation system according to claim 1 .

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