Combined cycle power generation facilities

Abstract

To provide a combined-cycle power generation facility which can raise temperature of steam introduced into a steam turbine, to high temperature, can obtain large heat drop in a heat cycle, and can improve heat efficiency.SOLUTION: A combined cycle power generation facility 1 in the present embodiment comprises: a first waste heat recovery boiler 30 provided with a reheating unit 50 and a high-pressure steam generation unit 41 using exhaust from a gas turbine 10; a high-pressure turbine 71 into which steam is introduced from the high-pressure steam generation unit 41; a combustor 75 for combusting hydrogen and oxygen; a reheat steam pipe 63 connecting the high-pressure turbine 71 and the combustor 75 together with the reheating unit 50 interposed; an oxygen-hydrogen combustion turbine 72 into which the steam is introduced from the combustor 75; a second waste heat recovery boiler 80 having a steam generation unit 90 for utilizing exhaust from the oxygen-hydrogen combustion turbine 72; a low-pressure turbine 73 into which the steam is introduced from the steam generation unit 90; and a condenser 74 for condensing the steam which is discharged from the low-pressure turbine 73.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a combined cycle power plant. [Background technology]

[0002] In recent years, there has been an increasing demand for combined cycle power generation equipment, which can achieve high thermal efficiency, in thermal power plants. Conventional combined cycle power generation equipment includes a gas turbine, a heat recovery steam generator, a steam turbine, and a generator. In this combined cycle power generation equipment, high-temperature exhaust gas from the gas turbine is introduced into the heat recovery steam generator. Steam generated in the heat recovery steam generator is introduced into the steam turbine.

[0003] In such combined cycle power generation facilities, techniques for improving the thermal efficiency of the cycle are being studied. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-85608 Summary of the Invention [Problem to be solved by the invention]

[0005] In a conventional combined cycle power plant, the temperature of the steam generated by the heat recovery steam generator is lower than the exhaust temperature of the gas turbine. Furthermore, there is a limit to how much the temperature of the steam introduced into the steam turbine can be increased while maintaining the exhaust temperature of the conventional gas turbine. Therefore, it is difficult to further improve the thermal efficiency of the cycle while maintaining the exhaust temperature of the conventional gas turbine.

[0006] The problem to be solved by the present invention is to provide a combined cycle power generation facility that can increase the temperature of steam introduced into a steam turbine, obtain a large heat drop in the thermal cycle, and improve thermal efficiency. [Means for solving the problem]

[0007] The combined cycle power generation facility of the embodiment includes a gas turbine, a first heat recovery boiler having a first steam generation section that generates steam using the heat of exhaust from the gas turbine and a reheat section that reheats the steam, and a first steam turbine into which the steam generated in the first steam generation section is introduced.

[0008] The combined cycle power generation equipment also includes a combustor that combusts hydrogen and oxygen, a reheat steam pipe that connects the steam outlet of the first steam turbine to the combustor via the reheat section, a second steam turbine that is connected to the combustor and into which steam discharged from the combustor is introduced, a second heat recovery boiler that has a second steam generating section that generates steam using the heat of the steam discharged from the second steam turbine, a third steam turbine that receives the steam generated in the second steam generating section, and a condenser that condenses the steam discharged from the third steam turbine. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a system diagram schematically illustrating a configuration of a combined cycle power generation facility according to an embodiment. [Figure 2] 1 is an hs diagram showing a part of a thermal cycle of a combined cycle power generation facility according to an embodiment. [Figure 3] FIG. 1 is an hs diagram showing a part of the thermal cycle of a combined cycle power generation facility of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] Fig. 1 is a system diagram schematically illustrating the configuration of a combined cycle power generation facility 1 according to an embodiment. As shown in Fig. 1, the combined cycle power generation facility 1 includes a gas turbine 10, a steam turbine system 70, and a generator 20 as main components.

[0012] The gas turbine 10 includes a compressor 11, a combustor 12, and a turbine 13. The generator 20 is arranged on the same axis as the compressor 11 and the turbine 13. The rotors of the compressor 11, the turbine 13, and the generator 20 are configured to rotate integrally.

[0013] The compressor 11, for example, takes in and compresses air and supplies the air to the combustor 12. The fuel supply unit 14 supplies fuel to the combustor 12. In the combustor 12, the fuel and compressed air are combusted to generate combustion gas.

[0014] Although an example in which compressed air is used as the oxidant is shown here, the oxidant is not limited to air. For example, oxygen may be used as the oxidant. The fuel is not particularly limited. For example, hydrocarbons such as methane and natural gas, hydrogen, ammonia, a composite fuel of hydrocarbons and hydrogen, or a composite fuel of hydrocarbons and ammonia may be used as the fuel. Furthermore, for example, a coal gasification gas fuel containing carbon monoxide and hydrogen, or a coal gasification gas fuel containing ammonia may be used as the fuel.

[0015] The combustion gas generated in the combustor 12 is supplied to the turbine 13 to rotate the turbine 13. The rotation of the turbine 13 drives the generator 20 and the compressor 11. The combustion gas discharged from the turbine 13 is guided to the first heat recovery boiler 30 as exhaust gas.

[0016] The steam turbine system 70 includes a first heat recovery steam generator (HRSG) 30, multiple steam turbines, a combustor 75, a second heat recovery steam generator (HRSG) 80, and a condenser 74. The steam turbine system 70 also includes a condensate supply system and a condensate discharge system.

[0017] The first heat recovery boiler 30 includes a flow path 31 into which exhaust gas from the gas turbine 10 is introduced, a steam generating section 40 and a reheating section 50 provided in the flow path 31, and a chimney 32 that discharges the exhaust gas that has passed through the steam generating section 40 to the outside. The steam generating section 40 generates steam by utilizing the heat contained in the exhaust gas. The reheating section 50 reheats the steam by utilizing the heat contained in the exhaust gas.

[0018] The steam generating unit 40 includes, for example, a high-pressure steam generating unit 41, a medium-pressure steam generating unit 42, and a low-pressure steam generating unit 43. These steam generating units are arranged in the order of the high-pressure steam generating unit 41, the medium-pressure steam generating unit 42, and the low-pressure steam generating unit 43 from the side where the exhaust gas is introduced.

[0019] The high-pressure steam generating unit 41 includes a first high-pressure superheater 41a, a second high-pressure superheater 41b, a high-pressure steam drum 41c, a high-pressure evaporator 41d, and a high-pressure economizer 41e. The high-pressure steam drum 41c is connected to the high-pressure evaporator 41d. The high-pressure economizer 41e is connected to a feedwater pipe 67 that introduces feedwater from the condenser 74. Note that although an example including two high-pressure superheaters is shown here, a configuration including one high-pressure superheater may also be used.

[0020] The water heated in the high-pressure economizer 41e is introduced into the high-pressure steam drum 41c and becomes steam in the high-pressure evaporator 41d. The steam generated in the high-pressure evaporator 41d is introduced into the second high-pressure superheater 41b and the first high-pressure superheater 41a and superheated. The superheated steam is introduced to the high-pressure turbine 71 via the main steam pipe 60.

[0021] The intermediate-pressure steam generating unit 42 includes an intermediate-pressure superheater 42a, an intermediate-pressure steam drum 42b, an intermediate-pressure evaporator 42c, and an intermediate-pressure economizer 42d. The intermediate-pressure steam drum 42b is connected to the intermediate-pressure evaporator 42c. The intermediate-pressure economizer 42d is connected to, for example, a low-pressure economizer 43d.

[0022] The water supplied from the low-pressure economizer 43d is heated in the intermediate-pressure economizer 42d. The water heated in the intermediate-pressure economizer 42d is introduced into the intermediate-pressure steam drum 42b and converted into steam in the intermediate-pressure evaporator 42c. The steam generated in the intermediate-pressure evaporator 42c is introduced into the intermediate-pressure superheater 42a and superheated. The superheated steam is introduced via a steam pipe 62 to a low-temperature reheat steam pipe 64, which will be described later. A steam valve 62a that adjusts the flow rate of steam introduced into the low-temperature reheat steam pipe 64 is interposed in the steam pipe 62.

[0023] The low-pressure steam generating unit 43 includes a low-pressure superheater 43a, a low-pressure steam drum 43b, a low-pressure evaporator 43c, and a low-pressure economizer 43d. The low-pressure steam generating unit 43 functions as a third steam generating unit. The low-pressure steam drum 43b is connected to the low-pressure evaporator 43c. The low-pressure economizer 43d is connected to a feedwater pipe 67a that introduces feedwater from the condenser 74.

[0024] The water heated in the low-pressure economizer 43d is introduced into the low-pressure steam drum 43b and becomes steam in the low-pressure evaporator 43c. Note that a portion of the water heated in the low-pressure economizer 43d is introduced into the intermediate-pressure economizer 42d. The steam generated in the low-pressure evaporator 43c is introduced into the low-pressure superheater 43a and superheated. The superheated steam is introduced to a predetermined turbine stage of the low-pressure turbine 73 via a steam supply pipe 61. Note that a steam valve 61a that adjusts the flow rate of steam introduced into the low-pressure turbine 73 is interposed in the steam supply pipe 61.

[0025] The steam is introduced into a turbine stage downstream of the first turbine stage, for example, via a steam supply pipe 61. By introducing steam into a predetermined turbine stage in this manner, the turbine output is increased.

[0026] The reheat section 50 is disposed, for example, between the first high-pressure superheater 41 a and the second high-pressure superheater 41 b. A steam inlet of the reheat section 50 is connected to a low-temperature reheat steam pipe 64, and a steam outlet of the reheat section 50 is connected to a high-temperature reheat steam pipe 65.

[0027] The multiple steam turbines include a high-pressure turbine 71, an oxygen-hydrogen combustion turbine 72, and a low-pressure turbine 73. The high-pressure turbine 71 functions as a first steam turbine, the oxygen-hydrogen combustion turbine 72 functions as a second steam turbine, and the low-pressure turbine 73 functions as a third steam turbine.

[0028] 1, the compressor 11, turbine 13, generator 20, high-pressure turbine 71, oxygen-hydrogen combustion turbine 72, and low-pressure turbine 73 are arranged on the same axis, and their rotors are configured to rotate integrally. Note that, for example, the gas turbine 10 and steam turbines 71, 72, and 73 may each be connected to a separate generator.

[0029] The steam inlet of the high-pressure turbine 71 is connected to the first high-pressure superheater 41a via a main steam pipe 60. A steam valve 60a that adjusts the flow rate of steam introduced into the high-pressure turbine 71 is provided in the main steam pipe 60.

[0030] A steam outlet of the high-pressure turbine 71 is connected to the combustor 75 via a reheat steam pipe 63 that interposes the reheat section 50. The reheat steam pipe 63 includes a low-temperature reheat steam pipe 64 that connects the steam outlet of the high-pressure turbine 71 and the reheat section 50, and a high-temperature reheat steam pipe 65 that connects the reheat section 50 and the combustor 75. For example, a steam valve 65a that adjusts the flow rate of steam introduced into the combustor 75 is interposed in the high-temperature reheat steam pipe 65.

[0031] The combustor 75 combusts fuel and an oxidizer. The combustor 75 is provided, for example, at the steam inlet portion of the oxygen-hydrogen combustion turbine 72. The combustor 75 includes a fuel supply unit 75a that supplies fuel and an oxidizer supply unit 75b that supplies an oxidizer. The fuel supplied to the combustor 75 is hydrogen (H2). The oxidizer supplied to the combustor 75 is oxygen (O2). Therefore, the combustor 75 generates water vapor as combustion gas.

[0032] The steam generated in the combustor 75 is mixed with steam introduced into the combustor 75 via the high-temperature reheat steam pipe 65, and is introduced into the oxygen-hydrogen combustion turbine 72. That is, the oxygen-hydrogen combustion turbine 72 receives steam that is a mixture of steam reheated in the reheat section 50 and the steam generated in the combustor 75.

[0033] The steam outlet of the oxygen-hydrogen combustion turbine 72 is connected to the second heat recovery steam generator 80 via a steam pipe 102. In other words, the steam pipe 102 connects the steam outlet of the oxygen-hydrogen combustion turbine 72 and the steam inlet of the second heat recovery steam generator 80.

[0034] A steam inlet of the low-pressure turbine 73 is connected to a superheater 90a of the second heat recovery boiler 80 via a steam pipe 100. A steam valve 100a that adjusts the flow rate of steam introduced into the low-pressure turbine 73 is disposed in the steam pipe 100. A steam outlet of the low-pressure turbine 73 is connected to a condenser 74 via an exhaust pipe 66.

[0035] The second heat recovery boiler 80 includes a flow path 81 into which exhaust gas from the oxygen-hydrogen combustion turbine 72 is introduced, and a steam generating unit 90 provided in the flow path 81. The steam generating unit 90 generates steam by utilizing the heat of the steam discharged from the oxygen-hydrogen combustion turbine 72. The steam generating unit 90 functions as a second steam generating unit.

[0036] The steam generating unit 90 includes a superheater 90a, a steam drum 90b, an evaporator 90c, and an economizer 90d. The steam drum 90b is connected to the evaporator 90c. The economizer 90d is connected to a feedwater pipe 67b that introduces feedwater from the condenser 74. A steam outlet of the second heat recovery boiler 80 is connected to the steam supply pipe 61 via a steam pipe 101. A steam valve 101a that adjusts the flow rate of steam introduced into the steam supply pipe 61 is provided in the steam pipe 101.

[0037] The water heated in the economizer 90d is introduced into the steam drum 90b and becomes steam in the evaporator 90c. The steam generated in the evaporator 90c is introduced into the superheater 90a and superheated. The superheated steam is introduced to the low-pressure turbine 73 via a steam pipe 100.

[0038] The steam discharged from the second heat recovery boiler 80 is introduced into the steam supply pipe 61 via a steam pipe 101. The steam introduced into the steam supply pipe 61 is led to a predetermined turbine stage of the low-pressure turbine 73 together with the steam discharged from the low-pressure superheater 43a.

[0039] The condensate supply system supplies condensate generated in the condenser 74 to the first heat recovery steam generator 30 and the second heat recovery steam generator 80. The condensate supply system includes water supply pipes 67, 67a, 67b, a low-pressure water supply pump 76, and high-pressure water supply pumps 77a, 77b.

[0040] One end of the water supply pipe 67 is connected to the condenser 74, and the other end of the water supply pipe 67 is connected to the high-pressure economizer 41e. A low-pressure water supply pump 76 and a high-pressure water supply pump 77a are interposed in the water supply pipe 67.

[0041] One end of the water supply pipe 67a is connected to the water supply pipe 67 downstream of the high-pressure water supply pump 77a. The other end of the water supply pipe 67a is connected to the low-pressure economizer 43d.

[0042] One end of the water supply pipe 67b is connected to the water supply pipe 67 between the low-pressure water supply pump 76 and the high-pressure water supply pump 77a. The other end of the water supply pipe 67b is connected to the economizer 90d. A high-pressure water supply pump 77b is interposed in the water supply pipe 67b.

[0043] The condensate generated in the condenser 74 is pumped to the high-pressure economizer 41e and the low-pressure economizer 43d by the low-pressure feed water pump 76 and the high-pressure feed water pump 77a. The condensate generated in the condenser 74 is also pumped to the economizer 90d by the low-pressure feed water pump 76 and the high-pressure feed water pump 77b.

[0044] The condensate discharge system removes the amount of water condensed from the steam generated in the combustor 75 from the condensate generated in the condenser 74. The condensate discharge system includes a discharge pipe 69 and a flow rate adjustment valve 69a.

[0045] One end of the discharge pipe 69 is connected to the water supply pipe 67 between the low-pressure water supply pump 76 and the high-pressure water supply pump 77a. A flow rate adjustment valve 69a is provided in the discharge pipe 69 to adjust the amount of water discharged. The other end of the discharge pipe 69 is open to the outside, for example.

[0046] Of the condensate pumped by the low-pressure feedwater pump 76, an amount equivalent to the amount of water condensed from the steam generated in the combustor 75 is discharged to the outside via the discharge pipe 69.

[0047] Here, the operation of the steam turbine system 70 will be described.

[0048] The steam introduced into the high-pressure turbine 71 via the main steam pipe 60 rotates the high-pressure turbine 71, and then is discharged to the low-temperature reheat steam pipe 64. The steam discharged to the low-temperature reheat steam pipe 64 is led to the reheat section 50. At this time, for example, steam is introduced into the low-temperature reheat steam pipe 64 from the intermediate-pressure superheater 42a via the steam pipe 62.

[0049] The steam guided to the reheat section 50 via the low-temperature reheat steam pipe 64 is reheated and guided to the high-temperature reheat steam pipe 65. The steam is then introduced into the combustor 75 via the high-temperature reheat steam pipe 65.

[0050] In the combustor 75, high-temperature steam is generated by the combustion of hydrogen and oxygen. The steam generated in the combustor 75 is mixed with steam introduced into the combustor 75 via the high-temperature reheat steam pipe 65, and becomes steam introduced into the oxygen-hydrogen combustion turbine 72. The temperature of the steam introduced into the combustor 75 is increased by being mixed with the steam generated in the combustor 75. In other words, by providing the combustor 75, steam at a temperature higher than the temperature of the steam reheated in the reheat section 50 is introduced into the oxygen-hydrogen combustion turbine 72.

[0051] The steam introduced into the oxygen-hydrogen combustion turbine 72 rotates the oxygen-hydrogen combustion turbine 72, and then is introduced into the second heat recovery boiler 80 via a steam pipe 102. Steam generated in a steam generating section 90 of the second heat recovery boiler 80 is introduced into the low-pressure turbine 73 via a steam pipe 100. The steam introduced into the low-pressure turbine 73 rotates the low-pressure turbine 73, and then is discharged into the exhaust pipe 66.

[0052] The state of the steam introduced into the oxygen-hydrogen combustion turbine 72 is adjusted by settings such as the amount of heat input into the combustor 75. The state of the steam discharged from the oxygen-hydrogen combustion turbine 72 is adjusted by settings such as the configuration of the oxygen-hydrogen combustion turbine 72 and the amount of heat input into the combustor 75. The pressure and temperature of the steam introduced into the low-pressure turbine 73 are adjusted by the state of the steam introduced into the second heat recovery boiler 80 and the configuration of the steam generating unit 90.

[0053] Here, the pressure of the steam introduced into the low-pressure turbine 73 via the steam pipe 100 is set to be higher than the pressure of the steam discharged from the oxygen-hydrogen combustion turbine 72. The state of the steam from the steam inlet of the combustor 75 to the steam outlet of the low-pressure turbine 73 will be described in detail later.

[0054] The steam discharged from the low-pressure superheater 43a is guided to a predetermined turbine stage of the low-pressure turbine 73 via a steam supply pipe 61. Furthermore, the steam discharged from the second heat recovery boiler 80 is guided to a predetermined turbine stage of the low-pressure turbine 73 via a steam pipe 101 and a steam supply pipe 61. By introducing the steam discharged from the low-pressure superheater 43a and the steam discharged from the second heat recovery boiler 80 into the predetermined turbine stage, the turbine output is increased.

[0055] The steam introduced into the low-pressure turbine 73 rotates the low-pressure turbine 73, and then is discharged to the exhaust pipe 66. The steam discharged to the exhaust pipe 66 is introduced into the condenser 74 and becomes condensed water.

[0056] As described above, the condensate from the condenser 74 is pumped by the low-pressure feed water pump 76 and the high-pressure feed water pumps 77a and 77b and is guided to the high-pressure economizer 41e, the low-pressure economizer 43d, and the economizer 90d via the feed water pipes 67, 67a, and 67b. Note that the amount of water condensed in the condenser 74 from the steam generated in the combustor 75 is discharged via the discharge pipe 69.

[0057] Next, the state of steam from the steam inlet of the combustor 75 to the steam outlet of the low-pressure turbine 73 will be described.

[0058] 2 is an hs diagram showing a part of the thermal cycle of the combined cycle power generation facility 1 according to the embodiment. In FIG. 2, the state of steam from the steam inlet of the combustor 75 to the steam outlet of the low-pressure turbine 73 is shown.

[0059] In Figure 2, the horizontal axis represents the steam specific entropy (kJ / (kg·K)), and the vertical axis represents the steam specific enthalpy h (kJ / kg). Also in Figure 2, isobars are shown by dashed lines, and isotherms are shown by dashed double-dashed lines. In Figure 2, the saturation limit line is indicated by BC.

[0060] In FIG. 2, state a is the state of steam introduced into the combustor 75 via the high-temperature reheat steam pipe 65 .

[0061] State b is the state of steam discharged from the combustor 75, in other words, the state of steam introduced into the steam inlet of the oxygen-hydrogen combustion turbine 72. The temperature of the steam in state b is higher than the temperature of the steam introduced into the high-pressure turbine 71. The temperature of the steam in state b can also be higher than the temperature of the exhaust gas introduced from the gas turbine 10 into the first heat recovery steam generator 30. In FIG. 2, the hydrogen input heat amount input in the combustor 75 is indicated by H1.

[0062] State c is the state of steam at the steam outlet of the oxygen-hydrogen combustion turbine 72, in other words, the state of steam introduced into the second heat recovery steam generator 80. The line connecting state b and state c is the expansion line in the oxygen-hydrogen combustion turbine 72.

[0063] State d is the state of steam introduced into the steam inlet of the low-pressure turbine 73 via the steam pipe 100. State e is the state of steam at the steam outlet of the low-pressure turbine 73, in other words, the state of steam introduced into the condenser 74. The line connecting state d and state e is the expansion line in the low-pressure turbine 73. As shown in FIG. 2, the steam in state e becomes wet steam.

[0064] Here, in FIG. 2, the expansion lines (lines connecting state a and state f) in the intermediate-pressure turbine and low-pressure turbine of a conventional combined-cycle power generation facility are shown by dashed lines.

[0065] Conventional combined cycle power generation equipment does not include a combustor in the intermediate-pressure turbine. Furthermore, conventional combined cycle power generation equipment does not include a second heat recovery steam generator. Therefore, steam reheated in the reheat section 50 is introduced into the intermediate-pressure turbine via a high-temperature reheat steam pipe. Then, steam discharged from the intermediate-pressure turbine is introduced into the low-pressure turbine.

[0066] Therefore, in a conventional combined cycle power plant, state a is the state of steam introduced into the steam inlet of the intermediate pressure turbine through the hot reheat steam pipe, and state f is the state of steam at the steam outlet of the low pressure turbine.

[0067] 2, the enthalpy of steam at the steam inlet of the oxygen-hydrogen combustion turbine 72 of this embodiment is higher than the enthalpy of steam at the steam inlet of the intermediate-pressure turbine of a conventional combined cycle power generation facility by an amount equivalent to the hydrogen input heat quantity H1. Also, the pressure and enthalpy of steam at the steam outlet of the low-pressure turbine 73 of this embodiment are reduced to the same levels as the pressure and enthalpy of steam at the steam outlet of the low-pressure turbine of a conventional combined cycle power generation facility.

[0068] 2, in the combined cycle power generation facility 1 of this embodiment, the pressure of the steam introduced into the steam inlet of the low-pressure turbine 73 (pressure in state d) is set higher than the pressure of the steam at the steam outlet of the oxygen-hydrogen combustion turbine 72 (pressure in state c). Therefore, the expansion line in the low-pressure turbine 73 is shifted to the left on the hs diagram in FIG.

[0069] 2, the enthalpy of the steam discharged from the low-pressure turbine 73 is maintained at approximately the same level as the enthalpy of the steam discharged from a conventional low-pressure turbine. That is, even when the temperature of the steam introduced into the oxygen-hydrogen combustion turbine 72 is increased, the enthalpy of the steam discharged from the low-pressure turbine 73 can be maintained at approximately the same level as the enthalpy of the steam discharged from a conventional low-pressure turbine.

[0070] This provides a large heat drop between the oxygen-hydrogen combustion turbine 72 and the low-pressure turbine 73. Therefore, the hydrogen input heat amount H1 in the combustor 75 is effectively converted into power, improving thermal efficiency.

[0071] Furthermore, by setting the pressure in state d higher than the pressure in state c, the steam in state f can be made wet steam. This makes it possible to increase the temperature of the steam at the steam inlet of the oxygen-hydrogen combustion turbine 72 while using an existing low-pressure turbine 73 in which the stationary vanes and rotor blades of the downstream turbine stages are designed to handle wet steam.

[0072] Here, FIG. 3 is an hs diagram showing a part of the thermal cycle of a combined cycle power generation facility of a comparative example.

[0073] In the combined cycle power generation system of the comparative example, it is assumed that a combustor is provided at the steam inlet of the intermediate-pressure turbine of a conventional combined cycle power generation system. The configuration of the combustor provided in the intermediate-pressure turbine is the same as the combustor 75 of this embodiment. The comparative example is shown for comparison with this embodiment, and is not included in this embodiment.

[0074] In conventional combined cycle power plants, steam from the heat recovery steam generator is introduced into the high-pressure turbine. The steam discharged from the high-pressure turbine is reheated in the reheat section of the heat recovery steam generator and introduced into the intermediate-pressure turbine. The steam discharged from the intermediate-pressure turbine is introduced into the low-pressure turbine.

[0075] The combined cycle power generation system of the comparative example is assumed to be equipped with a combustor at the steam inlet of the intermediate-pressure turbine in this conventional combined cycle power generation system. Therefore, in the combined cycle power generation system of the comparative example, steam discharged from the high-pressure turbine is reheated in a reheat section in the heat recovery steam generator and introduced into the combustor via a high-temperature reheat steam pipe. The steam discharged from the combustor is introduced into the intermediate-pressure turbine. The steam discharged from the intermediate-pressure turbine is introduced into the low-pressure turbine. The combined cycle power generation system of the comparative example does not have the second heat recovery steam generator 80 that is equipped in the combined cycle power generation system 1 of this embodiment.

[0076] FIG. 3 shows the state of steam from the steam inlet of the combustor to the steam outlet of the low-pressure turbine.

[0077] In Fig. 3, state a is the state of steam introduced into the combustor through the high-temperature reheat steam pipe, and state f is the state of steam at the steam outlet of the low-pressure turbine of a conventional combined cycle power plant that does not have a combustor in the intermediate-pressure turbine, as described with reference to Fig. 2.

[0078] State m is the state of the steam discharged from the combustor, in other words, the state of the steam introduced into the steam inlet of the intermediate-pressure turbine. In Figure 3, the hydrogen input heat amount input in the combustor is indicated by H2.

[0079] State n is the state of the steam at the steam outlet of the low-pressure turbine, in other words, the state of the steam introduced into the condenser. The line connecting state m and state n is the expansion line for the intermediate-pressure turbine and the low-pressure turbine.

[0080] 3, the increase in enthalpy of the steam discharged from the low-pressure turbine due to an increase in the temperature of the steam introduced into the steam inlet of the intermediate-pressure turbine is indicated by H3. That is, the increase in enthalpy H3 is the difference between the enthalpy of the steam discharged from the low-pressure turbine when a combustor is provided and the enthalpy of the steam discharged from the low-pressure turbine when a combustor is not provided.

[0081] As described above, in the comparative example, by providing a combustor, the expansion lines in the intermediate-pressure turbine and the low-pressure turbine shift from the line connecting state a and state f to the line connecting state m and state n. Here, the hydrogen input heat quantity H2 is adjusted so that the steam in state n becomes wet steam.

[0082] In the comparative example shown in Figure 3, the increase in heat drop ΔH in the intermediate-pressure turbine and low-pressure turbine due to the inclusion of a combustor is H2 - H3. As shown in Figure 3, in the comparative example, even with the inclusion of a combustor, the increase in heat drop ΔH relative to the hydrogen input heat amount H2 is small. This tendency remains the same even when the hydrogen input heat amount H2 is further increased. Note that the hydrogen input heat amount H2 is limited in order to reduce the enthalpy of state n to the enthalpy required for wet steam formation.

[0083] Thus, in the comparative example not provided with the second heat recovery boiler 80, even if a combustor is provided, a sufficient improvement in thermal efficiency cannot be expected.

[0084] In contrast, according to the combined cycle power generation equipment 1 of the embodiment, by providing the combustor 75 and the second heat recovery boiler 80, it is possible to increase the temperature of the steam introduced into the oxygen-hydrogen combustion turbine 72 while making the pressure of the steam introduced into the low-pressure turbine 73 higher than the pressure of the steam exhausted from the oxygen-hydrogen combustion turbine 72.

[0085] This provides a large heat drop in the heat cycle, effectively utilizing the hydrogen input heat amount H1 in the combustor 75 and improving thermal efficiency. In addition, the steam discharged from the low-pressure turbine 73 can be made wet steam, allowing an existing low-pressure turbine to be used as the low-pressure turbine 73.

[0086] According to the embodiment described above, it is possible to increase the temperature of steam introduced into the steam turbine, and a large heat drop can be obtained in the thermal cycle, thereby making it possible to improve thermal efficiency.

[0087] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0088] 1... combined cycle power generation equipment, 10... gas turbine, 11... compressor, 12, 75... combustor, 13... turbine, 14, 75a... fuel supply section, 20... generator, 30... first heat recovery boiler, 31, 81... flow path, 32... chimney, 40, 90... steam generation section, 41... high-pressure steam generation section, 41a... first high-pressure superheater, 41b... second high-pressure superheater, 41c... high-pressure steam drum, 41d... high-pressure evaporator, 41e... high-pressure economizer, 42... intermediate-pressure steam generation section, 42a... intermediate-pressure superheater, 42b... intermediate-pressure steam drum, 42c... intermediate-pressure evaporator, 42d... intermediate-pressure economizer, 43... low-pressure steam generation section, 43a... low-pressure superheater, 43b... low-pressure steam drum, 43c... low-pressure evaporator, 43d... low-pressure economizer, 50... Reheat section, 60...main steam pipe, 60a, 61a, 62a, 65a, 100a, 101a...steam valve, 61...steam supply pipe, 62, 100, 101, 102...steam pipe, 63...reheat steam pipe, 64...low-temperature reheat steam pipe, 65...high-temperature reheat steam pipe, 66...exhaust pipe, 67, 67a, 67b...feed water pipe, 69...discharge pipe, 69a...flow control valve, 70...steam turbine system, 71...high-pressure turbine, 72...oxygen-hydrogen combustion turbine, 73...low-pressure turbine, 74...condenser, 75b...oxidizer supply section, 76...low-pressure feed water pump, 77a, 77b...high-pressure feed water pump, 80...second heat recovery boiler, 90a...superheater, 90b...steam drum, 90c...evaporator, 90d...economiter, BC...saturation limit line.

Claims

1. A gas turbine, a first heat recovery boiler including a first steam generating section that generates steam and a reheating section that reheats the steam by utilizing heat of exhaust gas from the gas turbine; a first steam turbine into which steam generated in the first steam generating section is introduced; a combustor that burns hydrogen and oxygen; a reheat steam pipe connecting a steam outlet of the first steam turbine and the combustor via the reheat section; a second steam turbine coupled to the combustor and receiving steam discharged from the combustor; a second heat recovery boiler including a second steam generating unit that generates steam by utilizing heat of the steam discharged from the second steam turbine; a third steam turbine into which the steam generated in the second steam generating section is introduced; a condenser that condenses the steam discharged from the third steam turbine; A combined cycle power generation facility comprising:

2. 2. The combined cycle power generation facility according to claim 1, wherein the pressure of the steam introduced into the third steam turbine is higher than the pressure of the steam discharged from the second steam turbine.

3. 2. The combined cycle power generation facility according to claim 1, wherein the steam discharged from the second heat recovery boiler is introduced into a predetermined turbine stage of the third steam turbine.

4. the first heat recovery boiler includes a third steam generating unit that generates steam having a pressure lower than the pressure of the steam generated in the first steam generating unit, 2. The combined cycle power generation facility according to claim 1, wherein the steam generated in the third steam generating section is introduced into a predetermined turbine stage of the third steam turbine.

5. 2. The combined cycle power generation facility according to claim 1, further comprising a condensate supply system that supplies the condensate generated in the condenser to the first heat recovery boiler and the second heat recovery boiler.

6. 2. The combined cycle power generation facility according to claim 1, further comprising a condensate discharge system for removing from the condensate generated in the condenser an amount of water equivalent to the amount of water condensed from the steam generated in the combustor.

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