Combined cycle power generation equipment

Abstract

To provide a combined-cycle power generation facility which can perform two-stage reheating, and is improved in heat efficiency and an output.SOLUTION: A combined-cycle power generation facility 1 in the present embodiment comprises: a gas turbine 10; a waste heat recovery boiler 30 including a high-pressure steam generation unit 41 for generating steam by exhaust from the gas turbine 10, and a reheating unit 50 for reheating the steam; a high-pressure turbine 71 into which the steam from the high-pressure steam generation unit 41 is introduced; a middle-pressure turbine 72 provided on a downstream side of the high-pressure turbine 71; a reheat steam pipe 63 connecting an outlet of the high-pressure turbine 71 and an inlet of the middle-pressure turbine 72 together with the reheating unit 50 interposed; a combustor 75 into which steam discharged from the middle-pressure turbine 72 is introduced and which reheats the introduced steam by combusting oxygen and hydrogen; a low-pressure turbine 73 into which the steam discharged from the combustor 75 is introduced; 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] Embodiments of the present invention relate to combined cycle power generation equipment.

Background Art

[0002] In recent years, in thermal power plants, the demand for combined cycle power generation equipment with high plant thermal efficiency has been increasing. Conventional combined cycle power generation equipment includes a gas turbine, a heat recovery boiler, a steam turbine, and a generator. In this combined cycle power generation equipment, the high-temperature exhaust gas from the gas turbine is introduced into the heat recovery boiler. The steam turbine is composed of, for example, a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine.

[0003] In the heat recovery boiler, in order to effectively utilize the heat quantity of the exhaust gas from the gas turbine to generate steam, a configuration including steam generation units at three pressure levels of high pressure, medium pressure, and low pressure is adopted. The steam generated in the steam generation unit is introduced into the steam turbine.

[0004] In conventional combined cycle power generation equipment, in order to improve the thermal efficiency, a reheat cycle is adopted in which the steam exhausted from the high-pressure turbine is reheated in the reheater of the heat recovery boiler and introduced into the medium-pressure turbine. In this case, the temperature of the reheated steam introduced into the medium-pressure turbine is set to be, for example, approximately the same as the temperature of the main steam introduced into the high-pressure turbine.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] As described above, in a waste heat recovery boiler, the exhaust from the gas turbine is used as a heat source to generate steam. Therefore, as the exhaust passes through each steam generation section, the temperature of the exhaust decreases.

[0007] When employing the reheat cycle described above, and setting the temperature of the reheat steam introduced into the intermediate-pressure turbine to approximately the same temperature as the main steam introduced into the high-pressure turbine, the number of reheat cycles is limited to one in order to properly perform both steam generation and steam reheating in the waste heat recovery boiler. In other words, in conventional combined-cycle power generation equipment, one stage of reheating is the limit in the waste heat recovery boiler.

[0008] Therefore, in combined cycle power generation facilities that employ a conventional reheat cycle configuration, it is difficult to achieve further improvements in thermal efficiency through reheating.

[0009] The problem that this invention aims to solve is to provide a combined cycle power generation system that enables two-stage reheating and can improve thermal efficiency and output. [Means for solving the problem]

[0010] The combined cycle power generation equipment of this embodiment includes a gas turbine and a waste heat recovery boiler which has a steam generation unit that generates steam using the heat of the exhaust from the gas turbine and a reheat unit that reheats the steam.

[0011] Furthermore, this combined cycle power generation equipment includes a first steam turbine into which the steam generated in the steam generation unit is introduced; a second steam turbine provided downstream of the first steam turbine in the direction of steam flow; a reheat steam pipe connecting the steam outlet of the first steam turbine and the steam inlet of the second steam turbine via the reheat unit; a combustor into which the steam discharged from the second steam turbine is introduced and which reheats the introduced steam by burning oxygen and hydrogen; a third steam turbine into which the steam discharged from the combustor is introduced; and a condenser into which the steam discharged from the third steam turbine is converted into condensate. Furthermore, the temperature of the steam introduced into the second and third steam turbines is the same as the temperature of the steam introduced into the first steam turbine. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram showing the configuration of the combined cycle power generation equipment according to the first embodiment. [Figure 2] This figure shows the Ts diagram for a combined cycle power generation facility according to the first embodiment. [Figure 3] This is a schematic diagram showing the configuration of the combined cycle power generation equipment according to the second embodiment. [Figure 4] This figure shows the Ts diagram for a combined cycle power generation facility according to the second embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0014] (First Embodiment) Figure 1 is a schematic diagram showing the configuration of the combined cycle power generation equipment 1 according to the first embodiment.

[0015] As shown in Figure 1, the combined cycle power generation equipment 1 mainly consists of a gas turbine 10, a heat recovery steam generator (HRSG) 30, a steam turbine system 70, and a generator 20.

[0016] The gas turbine 10 includes a compressor 11, a combustor 12, and a turbine 13. A generator 20 is disposed on the same axis as the compressor 11 and the turbine 13. The respective rotors of the compressor 11, the turbine 13, and the generator 20 are configured to rotate integrally.

[0017] The compressor 11, for example, sucks in and compresses air and supplies it to the combustor 12. Fuel is supplied to the combustor 12 from a fuel supply unit 14. In the combustor 12, the fuel and the compressed air burn to generate combustion gas.

[0018] Here, an example using compressed air as an oxidant is shown, but the oxidant is not limited to air. For example, oxygen may be used as the oxidant. The fuel is not particularly limited. As the fuel, for example, hydrocarbons such as methane and natural gas, hydrogen, ammonia, a composite fuel of hydrocarbon and hydrogen, a composite fuel of hydrocarbon and ammonia, etc. may be used. Also, as the fuel, for example, a coal gasification gas fuel containing carbon monoxide and hydrogen, or a coal gasification gas fuel containing ammonia may be used.

[0019] 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 led to an exhaust heat recovery boiler 30 as exhaust.

[0020] The exhaust heat recovery boiler 30 includes a flow path 31 into which the exhaust from the gas turbine 10 is introduced, a steam generation unit 40 and a reheating unit 50 provided in the flow path 31, and a chimney 32 that discharges the exhaust passing through the steam generation unit to the outside. The steam generation unit 40 generates steam using the heat quantity of the exhaust. The reheating unit 50 reheats the steam using the heat quantity of the exhaust. Here, a natural circulation type steam generation unit 40 is illustrated and described. Note that the configuration of the steam generation unit 40 may be a forced circulation type or a once-through type configuration.

[0021] The steam generation unit 40 includes, for example, a high-pressure steam generation unit 41, an intermediate-pressure steam generation unit 42, and a low-pressure steam generation unit 43. These steam generation units are arranged in the order of the high-pressure steam generation unit 41, the intermediate-pressure steam generation unit 42, and the low-pressure steam generation unit 43 from the side where the exhaust is introduced.

[0022] The high-pressure steam generation 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 4ld, 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 feed water pipe 67b that guides the feed water from the condenser 74. Here, an example with two high-pressure superheaters is shown, but a configuration with one high-pressure superheater may also be used.

[0023] The water heated by 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 guided to the second high-pressure superheater A1b and the first high-pressure superheater 41a and superheated. The superheated steam is guided to the high-pressure turbine 71 through the main steam pipe 60.

[0024] The intermediate-pressure steam generation 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, the low-pressure economizer 43d.

[0025] The water supplied from the low-pressure economizer 43d is heated in the intermediate-pressure economizer 42d. The water heated by the intermediate-pressure economizer 42d is introduced into the intermediate-pressure steam drum 42b and becomes steam in the intermediate-pressure evaporator 42c. The steam generated in the intermediate-pressure evaporator 42c is guided to the intermediate-pressure superheater 42a and superheated. The superheated steam is guided to the low-temperature reheater steam pipe 64 described later through the steam pipe 69. A steam valve 69a for adjusting the flow rate of the steam introduced into the low-temperature reheater steam pipe 64 is interposed in the steam pipe 69.

[0026] The low-pressure steam generation unit 43 comprises 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 drum 43b is connected to the low-pressure evaporator 43c. The low-pressure economizer 43d is connected to a feedwater pipe 67a that carries feedwater from the condenser 74.

[0027] 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. The steam generated in the low-pressure evaporator 43c is led to the low-pressure superheater 43a where it is superheated. The superheated steam is led to predetermined turbine stages of the low-pressure turbine 73 via the steam supply pipe 61. The steam is introduced via the steam supply pipe 61 to turbine stages downstream of the first stage, for example. By introducing steam via the steam supply pipe 61 in this way, the turbine output can be increased.

[0028] The reheat section 50 is located, for example, between the first high-pressure superheater 41a and the second high-pressure superheater 41b. The steam inlet of the reheat section 50 is connected to the low-temperature reheat steam pipe 64, and the steam outlet of the reheat section 50 is connected to the high-temperature reheat steam pipe 65.

[0029] The steam turbine system 70 comprises a plurality of steam turbines, a condenser 74, and a combustor 75. The plurality of steam turbines include a high-pressure turbine 71, an intermediate-pressure turbine 72, and a low-pressure turbine 73. In the direction of steam flow, the intermediate-pressure turbine 72 is located downstream of the high-pressure turbine 71, and the low-pressure turbine 73 is located downstream of the intermediate-pressure turbine 72.

[0030] Furthermore, the high-pressure turbine 71 functions as the first steam turbine, the intermediate-pressure turbine 72 functions as the second steam turbine, and the low-pressure turbine 73 functions as the third steam turbine.

[0031] In the configuration shown in Figure 1, the compressor 11, turbine 13, generator 20, high-pressure turbine 71, intermediate-pressure turbine 72, and low-pressure turbine 73 are arranged on the same axis, and their rotors are configured to rotate as a single unit. For example, the gas turbine 10 and steam turbine may each be connected to separate generators.

[0032] The steam inlet of the high-pressure turbine 71 is connected to the first high-pressure superheater 41a via the main steam pipe 60. The main steam pipe 60 contains a steam valve 60a that adjusts the flow rate of steam introduced into the high-pressure turbine 71.

[0033] The steam outlet of the high-pressure turbine 71 is connected to the steam inlet of the intermediate-pressure turbine 72 via a reheat steam pipe 63 interposed through a reheat section 50. The reheat steam pipe 63 comprises a low-temperature reheat steam pipe 64 connecting the steam outlet of the high-pressure turbine 71 to the reheat section 50, and a high-temperature reheat steam pipe 65 connecting the reheat section 50 to the steam inlet of the intermediate-pressure turbine 72. For example, the high-temperature reheat steam pipe 65 includes a steam valve 65a that adjusts the flow rate of steam introduced into the intermediate-pressure turbine 72.

[0034] The steam outlet of the intermediate-pressure turbine 72 is connected to the steam inlet of the low-pressure turbine 73 via a steam pipe 62. A combustor 75 is interposed in the steam pipe 62.

[0035] The combustor 75 burns fuel and an oxidizer. The combustor 75 includes a fuel supply unit 75a that supplies fuel and an oxidizer supply unit 75b that supplies oxidizer. The fuel supplied to the combustor 75 is hydrogen (H2). The oxidizer supplied to the combustor 75 is oxygen (O2). Therefore, water vapor is produced as a combustion gas in the combustor 75.

[0036] Furthermore, steam discharged from the intermediate-pressure turbine 72 is introduced into the combustor 75. The combustor 75 reheats the introduced steam with the steam generated therein. The steam generated in the combustor 75 then mixes with the steam discharged from the steam outlet of the intermediate-pressure turbine 72 and is supplied to the low-pressure turbine 73.

[0037] Here, the steam pipe 62 may be equipped with a bypass pipe (not shown) that bypasses the combustor 75. By providing a bypass pipe, for example, when the combustor 75 is stopped for maintenance, the conventional single-stage reheat cycle can be performed without stopping the combined cycle power generation equipment 1. In this case, the steam pipe 62 is equipped with steam valves (not shown) near the inlet and outlet of the combustor 75, respectively. By closing these steam valves, the inflow of steam into the combustor 75 can be prevented when steam flows through the bypass pipe. The bypass pipe is equipped with a steam valve for adjusting the steam flow rate.

[0038] Although this example shows the combustor 75 interposed in the steam pipe 62, the combustor 75 may also be provided at the steam inlet of the low-pressure turbine 73.

[0039] A predetermined turbine stage of the low-pressure turbine 73 is connected to the low-pressure superheater 43a via a steam supply pipe 61. As mentioned above, the predetermined turbine stage is a turbine stage downstream of the first stage. A steam valve 61a is interposed in the steam supply pipe 61 to adjust the flow rate of steam introduced into the low-pressure turbine 73.

[0040] The steam outlet of the low-pressure turbine 73 is connected to the condenser 74 via the exhaust pipe 66. The condenser 74 is connected to the high-pressure economizer 41e and the low-pressure economizer 43d via feedwater pipes 67, 67a, and 67b. For example, the low-pressure feedwater pump 76 and the high-pressure feedwater pump 77 are interposed in the feedwater pipe 67. The feedwater pipe 67 branches into feedwater pipe 67a and feedwater pipe 67b downstream of the location where the high-pressure feedwater pump 77 is installed.

[0041] The condensate generated in the condenser 74 is pumped under pressure to the high-pressure economizer 41e and the low-pressure economizer 43d by the low-pressure feedwater pump 76 and the high-pressure feedwater pump 77. The feedwater pipes 67, 67a, 67b, the low-pressure feedwater pump 76, and the high-pressure feedwater pump 77 function as a condensate supply system.

[0042] Furthermore, the water supply pipe 67 is equipped with a discharge pipe 68 for removing the amount of water that has condensed from the steam generated in the combustor 75 from the condensate produced in the condenser 74. The discharge pipe 68 is equipped with a flow control valve 68a for adjusting the amount of water discharged. The discharge pipe 68 is connected to the water supply pipe 67 located, for example, between the low-pressure water supply pump 76 and the high-pressure water supply pump 77. The discharge pipe 68 and the flow control valve 68a function as a condensate discharge system for discharging the amount of water that has condensed from the steam generated in the combustor 75.

[0043] In the steam turbine system 70, the steam introduced to the high-pressure turbine 71 via the main steam pipe 60 rotates the high-pressure turbine 71 and is then discharged into the low-temperature reheat steam pipe 64. The steam discharged into the low-temperature reheat steam pipe 64 is then 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 69.

[0044] 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 to the intermediate-pressure turbine 72 via the high-temperature reheat steam pipe 65.

[0045] The steam introduced into the intermediate-pressure turbine 72 rotates the turbine 72 and is then discharged into the steam pipe 62. The steam discharged into the steam pipe 62 is then introduced into the combustor 75.

[0046] In the combustor 75, steam is generated by the combustion of hydrogen and oxygen. The steam generated in the combustor 75 is mixed with the steam introduced into the combustor 75 to become the steam introduced into the low-pressure turbine 73.

[0047] Here, the flow rate of steam introduced into the low-pressure turbine 73 increases by the flow rate of steam produced in the combustor 75. Also, the temperature of the steam discharged from the intermediate-pressure turbine 72 increases as it mixes with the high-temperature steam produced in the combustor 75. In other words, the steam discharged from the intermediate-pressure turbine 72 is reheated.

[0048] The temperature and flow rate of the steam introduced into the low-pressure turbine 73 are controlled by adjusting the combustion conditions of the combustor 75. For example, the temperature of the steam introduced into the low-pressure turbine 73 is adjusted to be approximately the same as the temperature of the steam introduced into the high-pressure turbine 71.

[0049] By increasing the temperature of the steam introduced into the low-pressure turbine 73 and further increasing the flow rate of the steam introduced into the low-pressure turbine 73, the thermal efficiency and output of the low-pressure turbine 73 are increased. In other words, the thermal efficiency and output are increased by providing the combustor 75.

[0050] The steam introduced into the low-pressure turbine 73 rotates the turbine 73 and is then discharged into the exhaust pipe 66.

[0051] The steam discharged into the exhaust pipe 66 is introduced into the condenser 74 and becomes condensate. The condensate from the condenser 74 is then pumped by the low-pressure feedwater pump 76 and the high-pressure feedwater pump 77, and guided through the feedwater pipes 67, 67a, and 67b to the high-pressure economizer 41e and the low-pressure economizer 43d.

[0052] As described above, in the combined cycle power generation equipment 1 of the first embodiment, two-stage reheating is achieved, consisting of reheating in the combustor 75 and reheating in the waste heat recovery boiler 30.

[0053] Here, Figure 2 shows the Ts diagram for the combined cycle power generation equipment 1 of the first embodiment. In Figure 2, the horizontal axis represents the specific entropy of steam (kJ / (kg·K)). The temperature on the horizontal axis is absolute zero. The vertical axis represents the steam temperature (K).

[0054] In Figure 2, the saturation limit line BC is shown by a dashed line. At the saturation limit line BC, the saturated liquid line SL is located below the critical point CP in terms of entropy, and the saturated vapor line SV is located above the critical point CP in terms of entropy. In Figure 2, each state in the thermal cycle of combined cycle power generation equipment 1 is indicated by the letters aj.

[0055] As shown in Figure 2, the two-stage reheat cycle in the combined cycle power generation equipment 1 proceeds in the order of state a, state b, state c...state j, state a. Here, the state between state a and state b is the state between the inlet of the low-pressure feedwater pump 76 and the inlet of the high-pressure economizer 41e, the state between state b and state c is the state between the inlet of the high-pressure economizer 41e and the inlet of the high-pressure steam drum 41c, the state between state c and state d is the state between the inlet of the high-pressure steam drum 41c and the inlet of the second high-pressure superheater 41b, the state between state d and state e is the state between the inlet of the second high-pressure superheater 41b and the steam inlet of the high-pressure turbine 71, and the state between state e and state f is the state between the steam inlet of the high-pressure turbine 71 and the steam inlet of the reheat section 50. The intermediate states, the state between state f and state g represent the state between the steam inlet of the reheat unit 50 and the steam inlet of the intermediate-pressure turbine 72, the state between state g and state h represent the state between the steam inlet of the intermediate-pressure turbine 72 and the steam inlet of the combustor 75, the state between state h and state i represent the state between the steam inlet of the combustor 75 and the steam inlet of the low-pressure turbine 73, the state between state i and state j represents the state between the steam inlet of the low-pressure turbine 73 and the steam inlet of the condenser 74, and the state between state j and state a represents the state between the steam inlet of the condenser 74 and the inlet of the low-pressure feedwater pump 76.

[0056] Here, we show an example where the first stage of reheating between state f and state g is performed by the reheating unit 50, and the second stage of reheating between state h and state i is performed by the combustor 75.

[0057] In Figure 2, the area enclosed by abcdefghij corresponds to the net work done in the two-stage reheat cycle of combined cycle power generation equipment 1. The area enclosed by abcdefghk corresponds to the net work done in the cycle of combined cycle power generation equipment 1 when the second stage of reheating is not performed (single-stage reheating).

[0058] As shown in Figure 2, the temperature of the vapor in state j is lower than the temperature of dry saturated vapor on the saturated vapor line SV at a specific entropy equal to the specific entropy of the vapor in state j. In other words, the vapor in state j is wet vapor.

[0059] By implementing two-stage reheating using the combustor 75 and the waste heat recovery boiler 30, the net amount of work corresponding to the area enclosed by hijk increases compared to when single-stage reheating is implemented using only the waste heat recovery boiler 30. In Figure 2, the portion of the net amount of work obtained by reheating in the combustor 75 is shown with solid hatching.

[0060] Here, the area enclosed by jklm corresponds to the amount of heat released in the condenser 74 from the amount of heat obtained by reheating in the combustor 75. In Figure 2, this portion of the released heat is indicated by dashed hatching.

[0061] In Figure 2, the steam temperature at the steam inlet of the combustor 75 also depends on the steam temperature at the steam inlet of the intermediate-pressure turbine 72, but is approximately 350°C even under low-temperature conditions. The steam temperature at the steam inlet of the low-pressure turbine 73 is, for example, over 500°C. The steam temperature at the steam inlet of the condenser 74 is, for example, approximately 30°C.

[0062] Therefore, the net work obtained by reheating in the combustor 75 (area of ​​the solid hatched line) is greater than the amount of heat dissipated in the condenser 74 (area of ​​the dashed hatched line), which is a portion of the heat obtained by reheating in the combustor 75. In addition, the average temperature during the heating process in the combustor 75 (from state h to state i) is higher than the average temperature during the heating process excluding the heating process in the combustor 75 (from state a to state e and from state f to state g). In other words, reheating in the combustor 75 improves the thermal efficiency of the cycle.

[0063] The temperatures of each steam mentioned above are examples only and are not limited to these. Even considering the temperature range of each steam mentioned above, the net work obtained by reheating in the combustor 75 (area of ​​the solid hatched line) is greater than the amount of heat dissipated in the condenser 74 (area of ​​the dashed hatched line), which is a portion of the heat obtained by reheating in the combustor 75.

[0064] As described above, the combined cycle power generation equipment 1 of the first embodiment is equipped with a combustor 75 that burns hydrogen and oxygen to generate steam and reheats the steam, making it possible to perform two-stage reheating while employing the configuration of a conventional waste heat recovery boiler, which is limited to one reheating cycle. In other words, the combined cycle power generation equipment 1, by being equipped with a combustor 75, can perform a total of two reheating cycles: one reheating cycle in the reheating section 50 of the waste heat recovery boiler 30 and one reheating cycle in the combustor 75 other than the waste heat recovery boiler 30.

[0065] In the combined cycle power generation equipment 1 of the first embodiment, the thermal efficiency of the cycle is improved by providing such a two-stage reheat cycle.

[0066] Furthermore, in the combined cycle power generation equipment 1 of the first embodiment, steam at a temperature similar to that of the steam introduced into the high-pressure turbine 71 can be introduced into the intermediate-pressure turbine 72 and the low-pressure turbine 73. This improves the thermal efficiency of the cycle.

[0067] Furthermore, the flow rate of steam introduced into the low-pressure turbine 73 increases by the amount of steam generated in the combustor 75. As a result, the turbine output increases.

[0068] As mentioned above, the fuel used in the combustor 12 of the gas turbine 10 is not particularly limited. For example, if a fuel containing hydrocarbons is used in the combustor 12 of the gas turbine 10, hydrogen is used as fuel in the combustor 75 of the steam turbine system 70, thereby reducing the amount of carbon dioxide (CO2) emitted per unit output in the combined cycle power generation facility 1.

[0069] In other words, in the combined cycle power generation facility 1, a portion of the output is obtained by utilizing steam generated in the combustor 75, which uses hydrogen fuel. Therefore, the amount of carbon dioxide (CO2) emitted per unit output in the combined cycle power generation facility 1 is lower than the amount of carbon dioxide (CO2) emitted per unit output in a combined cycle power generation facility where the entire output is obtained by steam generated using the exhaust from a gas turbine 10 that uses a fuel containing hydrocarbons.

[0070] (Second Embodiment) Figure 3 is a schematic diagram showing the configuration of the combined cycle power generation equipment 2 of the second embodiment. In the second embodiment, the same reference numerals are used for components identical to those of the combined cycle power generation equipment 1 of the first embodiment, and redundant explanations are omitted or simplified.

[0071] In the combined cycle power generation equipment 2 of the second embodiment, the combustor 75 is positioned between the high-pressure turbine 71 and the intermediate-pressure turbine 72, and the steam discharged from the intermediate-pressure turbine 72 is reheated in the waste heat recovery boiler 30. The other configurations are the same as those of the combined cycle power generation equipment 1 of the first embodiment. Therefore, this section will mainly describe the configurations that differ from those of the combined cycle power generation equipment 1 of the first embodiment.

[0072] As shown in Figure 3, in the steam turbine system 70, the steam inlet of the high-pressure turbine 71 is connected to the first high-pressure superheater 41a via the main steam pipe 60. The steam outlet of the high-pressure turbine 71 is connected to the steam inlet of the intermediate-pressure turbine 72 via the steam pipe 62. A combustor 75 is interposed in the steam pipe 62. The configuration of the combustor 75 is as described above.

[0073] Here, steam discharged from the high-pressure turbine 71 is introduced into the combustor 75. The combustor 75 reheats the introduced steam with water vapor produced by the combustion of oxygen and hydrogen. The water vapor produced in the combustor 75 then mixes with the steam discharged from the steam outlet of the high-pressure turbine 71 and is supplied to the intermediate-pressure turbine 72.

[0074] In the second embodiment as well, the steam pipe 62 may be provided with a bypass pipe (not shown) that bypasses the combustor 75. In this case, steam valves are provided in the steam pipe 62 near the inlet and outlet of the combustor 75, respectively. The effects of providing the bypass pipe are as described in the first embodiment.

[0075] Although this example shows the combustor 75 interposed in the steam pipe 62, the combustor 75 may also be provided at the steam inlet of the intermediate pressure turbine 72.

[0076] The steam outlet of the intermediate-pressure turbine 72 is connected to the steam inlet of the low-pressure turbine 73 via a reheat steam pipe 63 interposed through a reheat section 50. The reheat steam pipe 63 comprises a low-temperature reheat steam pipe 64 connecting the steam outlet of the intermediate-pressure turbine 72 to the reheat section 50, and a high-temperature reheat steam pipe 65 connecting the reheat section 50 to the steam inlet of the low-pressure turbine 73. For example, the high-temperature reheat steam pipe 65 includes a steam valve 65a that adjusts the flow rate of steam introduced into the low-pressure turbine 73.

[0077] As mentioned above, the steam outlet of the low-pressure turbine 73 is connected to the condenser 74 via the exhaust pipe 66.

[0078] In the steam turbine system 70, the steam introduced to the high-pressure turbine 71 via the main steam pipe 60 rotates the high-pressure turbine 71 and is then discharged into the steam pipe 62. The steam discharged into the steam pipe 62 is then introduced into the combustor 75.

[0079] In the combustor 75, steam is generated by the combustion of hydrogen and oxygen. The steam generated in the combustor 75 is mixed with the steam introduced into the combustor 75 to become the steam introduced into the intermediate-pressure turbine 72.

[0080] Here, the flow rate of steam introduced into the intermediate-pressure turbine 72 increases by the flow rate of steam produced in the combustor 75. Also, the temperature of the steam discharged from the high-pressure turbine 71 increases as it mixes with the high-temperature steam produced in the combustor 75. In other words, the steam discharged from the high-pressure turbine 71 is reheated.

[0081] The temperature and flow rate of the steam introduced into the intermediate-pressure turbine 72 are controlled by adjusting the combustion conditions of the combustor 75. For example, the temperature of the steam introduced into the intermediate-pressure turbine 72 is adjusted to be approximately the same as the temperature of the steam introduced into the high-pressure turbine 71.

[0082] By increasing the temperature of the steam introduced into the intermediate-pressure turbine 72 and further increasing the flow rate of the steam introduced into the intermediate-pressure turbine 72, the thermal efficiency and output of the intermediate-pressure turbine 72 are increased. In other words, the thermal efficiency and output are increased by providing the combustor 75.

[0083] The steam introduced into the intermediate-pressure turbine 72 rotates the turbine 72 and is then discharged into the low-temperature reheat steam pipe 64. The steam discharged into the low-temperature reheat steam pipe 64 is then 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 69.

[0084] 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 to the low-pressure turbine 73 via the high-temperature reheat steam pipe 65. After rotating the low-pressure turbine 73, the steam is discharged into the exhaust pipe 66.

[0085] Here, the flow rate of steam introduced into the low-pressure turbine 73 increases by the flow rate of steam generated in the combustor 75. Therefore, by providing the combustor 75, the output of the low-pressure turbine 73 also increases.

[0086] The steam discharged into the exhaust pipe 66 is introduced into the condenser 74 and becomes condensate. The condensate from the condenser 74 is then pumped by the low-pressure feedwater pump 76 and the high-pressure feedwater pump 77, and guided through the feedwater pipes 67, 67a, and 67b to the high-pressure economizer 41e and the low-pressure economizer 43d.

[0087] As described above, in the combined cycle power generation equipment 2 of the second embodiment, two-stage reheating is achieved, consisting of reheating in the combustor 75 and reheating in the waste heat recovery boiler 30.

[0088] Here, Figure 4 shows the Ts diagram for the combined cycle power generation equipment 2 of the second embodiment. In Figure 4, as in Figure 2, the horizontal axis represents the specific entropy of steam (kJ / (kg·K)), and the vertical axis represents the temperature of the steam (K). In Figure 4, each state in the thermal cycle of the combined cycle power generation equipment 2 is indicated by the letters aj.

[0089] As shown in Figure 4, the two-stage reheat cycle in the combined cycle power generation equipment 2 proceeds in the order of state a, state b, state c...state j, state a. Here, the state between state a and state b is the state between the inlet of the low-pressure feedwater pump 76 and the inlet of the high-pressure economizer 41e, the state between state b and state c is the state between the inlet of the high-pressure economizer 41e and the inlet of the high-pressure steam drum 41c, the state between state c and state d is the state between the inlet of the high-pressure steam drum 41c and the inlet of the second high-pressure superheater 41b, the state between state d and state e is the state between the inlet of the second high-pressure superheater 41b and the steam inlet of the high-pressure turbine 71, and the state between state e and state f is the state between the steam inlet of the high-pressure turbine 71 and the steam inlet of the combustor 75. The intermediate states, the state between state f and state g represent the state between the steam inlet of the combustor 75 and the steam inlet of the intermediate-pressure turbine 72, the state between state g and state h represent the state between the steam inlet of the intermediate-pressure turbine 72 and the steam inlet of the reheat unit 50, the state between state h and state i represent the state between the steam inlet of the reheat unit 50 and the steam inlet of the low-pressure turbine 73, the state between state i and state j represents the state between the steam inlet of the low-pressure turbine 73 and the steam inlet of the condenser 74, and the state between state j and state a represents the state between the steam inlet of the condenser 74 and the inlet of the low-pressure feedwater pump 76.

[0090] This example shows that the first stage of reheating between state f and state g is performed by the combustor 75, and the second stage of reheating between state h and state i is performed by the reheating unit 50.

[0091] In Figure 4, the area enclosed by abcdefghij corresponds to the net work done in the two-stage reheat cycle of the combined cycle power generation facility 2. The area enclosed by abcdel corresponds to the net work done in the cycle without reheating in the combined cycle power generation facility 2. The area enclosed by abcdefgk corresponds to the net work done in the cycle without second-stage reheating (single-stage reheating in combustor 75) in the combined cycle power generation facility 2.

[0092] As shown in Figure 4, the temperature of the vapor in state j is lower than the temperature of dry saturated vapor on the saturated vapor line SV at a specific entropy equal to the specific entropy of the vapor in state j. In other words, the vapor in state j is wet vapor.

[0093] By implementing two-stage reheating using the combustor 75 and the waste heat recovery boiler 30, the net amount of work corresponding to the area enclosed by fgkl increases compared to when single-stage reheating is implemented using only the waste heat recovery boiler 30. In Figure 4, the portion of the net amount of work obtained by reheating in the combustor 75 is shown with a solid hatched line.

[0094] Here, the area enclosed by klmn corresponds to the amount of heat released in the condenser 74 from the amount of heat obtained by reheating in the combustor 75. In Figure 4, this portion of the released heat is indicated by dashed hatching.

[0095] In Figure 4, the steam temperature at the steam inlet of the combustor 75 also depends on the steam temperature at the steam inlet of the high-pressure turbine 71, but even under low conditions, it is approximately 350°C. The steam temperature at the steam inlet of the intermediate-pressure turbine 72 is, for example, over 500°C. The steam temperature at the steam inlet of the condenser 74 is, for example, approximately 30°C.

[0096] Therefore, the net work obtained by reheating in the combustor 75 (area of ​​the solid hatched line) is greater than the amount of heat dissipated in the condenser 74 (area of ​​the dashed hatched line), which is a portion of the heat obtained by reheating in the combustor 75. In addition, the average temperature during the heating process in the combustor 75 (from state f to state g) is higher than the average temperature during the heating process excluding the heating process in the combustor 75 (from state a to state e and from state h to state i). In other words, reheating in the combustor 75 improves the thermal efficiency of the cycle.

[0097] The temperatures of each steam mentioned above are examples only and are not limited to these. Even considering the temperature range of each steam mentioned above, the net work obtained by reheating in the combustor 75 (area of ​​the solid hatched line) is greater than the amount of heat dissipated in the condenser 74 (area of ​​the dashed hatched line), which is a portion of the heat obtained by reheating in the combustor 75.

[0098] As described above, the combined cycle power generation equipment 2 of the second embodiment provides the same effects as the combined cycle power generation equipment 1 of the first embodiment. Specifically, the combined cycle power generation equipment 2 includes a combustor 75 that burns hydrogen and oxygen to generate steam and heats the steam, making it possible to perform two-stage reheating while employing the configuration of a conventional waste heat recovery boiler, which is limited to one reheating cycle. By incorporating such a two-stage reheating cycle, the thermal efficiency of the cycle is improved.

[0099] Furthermore, in the combined cycle power generation equipment 2 of the second embodiment, steam at a temperature similar to that of the steam introduced into the high-pressure turbine 71 can be introduced into the intermediate-pressure turbine 72 and the low-pressure turbine 73. This improves the thermal efficiency of the cycle.

[0100] Furthermore, the flow rate of steam introduced into the low-pressure turbine 73 increases by the amount of steam generated in the combustor 75. As a result, the turbine output increases.

[0101] Furthermore, when a fuel containing hydrocarbons is used as fuel for the combustor 12 of the gas turbine 10, as mentioned above, hydrogen is used as fuel for the combustor 75 in the steam turbine system 70, thus reducing the amount of carbon dioxide (CO2) emitted per unit output in the combined cycle power generation facility 2.

[0102] According to the embodiments described above, two-stage reheating is possible, and thermal efficiency and output can be improved.

[0103] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0104] 1, 2…Combined cycle power generation equipment, 10…Gas turbine, 11…Air compressor, 12, 75…Combustor, 13…Turbine, 14, 75a…Fuel supply unit, 20…Generator, 30…Waste heat recovery boiler, 31…Flow path, 32…Chimney, 40…Steam generation unit, 41…High-pressure steam generation unit, 41a…First high-pressure superheater, 41b…Second high-pressure superheater, 41c…High-pressure steam drum, 41d…High-pressure evaporator, 41e…High-pressure economizer, 42…Medium-pressure steam generation unit, 42a…Medium-pressure superheater, 42b…Medium-pressure steam drum, 42c…Medium-pressure evaporator, 42d…Medium-pressure economizer, 43…Low-pressure steam generation unit, 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, 65a, 69a...Steam valve, 61...Steam supply pipe, 62, 69...Steam pipe, 63...Reheat steam pipe, 64...Low-temperature reheat steam pipe, 65...High-temperature reheat steam pipe, 66...Exhaust pipe, 67, 67a, 67b...Feedwater pipe, 68...Discharge pipe, 68a...Flow control valve, 70...Steam turbine system, 71...High-pressure turbine, 72...Intermediate-pressure turbine, 73...Low-pressure turbine, 74...Condenser, 75b...Oxidizer supply section, 76...Low-pressure feedwater pump, 77...High-pressure feedwater pump, BC...Saturation limit line, CP...Critical point, SL...Saturated liquid line, SV...Saturated steam line.

Claims

1. Gas turbine and A waste heat recovery boiler comprising a steam generation unit that generates steam using the heat energy of the exhaust from the gas turbine and a reheat unit that reheats the steam, A first steam turbine into which the steam generated in the steam generation unit is introduced, In the direction of steam flow, a second steam turbine is provided downstream of the first steam turbine, A reheat steam pipe connecting the steam outlet of the first steam turbine and the steam inlet of the second steam turbine, with the aforementioned reheat section in between, Steam discharged from the second steam turbine is introduced into a combustor that reheats the introduced steam by burning oxygen and hydrogen, A third steam turbine into which the steam discharged from the aforementioned combustor is introduced, A condenser that converts the steam discharged from the third steam turbine into condensate, Equipped with, A combined cycle power generation system characterized in that the temperature of the steam introduced into the second steam turbine and the third steam turbine is the same as the temperature of the steam introduced into the first steam turbine.

2. The steam generation unit is a first steam generation unit that generates a first steam, The heat recovery boiler includes a second steam generation unit that generates a second steam at a pressure lower than the pressure of the first steam, The combined cycle power generation equipment according to claim 1, characterized in that the second steam is introduced into the reheat steam pipe between the steam outlet of the first steam turbine and the reheat section.

3. Gas turbine and A waste heat recovery boiler comprising a steam generation unit that generates steam using the heat energy of the exhaust from the gas turbine and a reheat unit that reheats the steam, A first steam turbine into which the steam generated in the steam generation unit is introduced, A combustor is provided into which steam discharged from the first steam turbine is introduced, and which reheats the introduced steam by burning oxygen and hydrogen. A second steam turbine into which the steam discharged from the aforementioned combustor is introduced, In the direction of steam flow, a third steam turbine is provided downstream of the second steam turbine, A reheat steam pipe connecting the steam outlet of the second steam turbine and the steam inlet of the third steam turbine, with the aforementioned reheat section in between, A condenser that converts the steam discharged from the third steam turbine into condensate, Equipped with, A combined cycle power generation system characterized in that the temperature of the steam introduced into the second steam turbine and the third steam turbine is the same as the temperature of the steam introduced into the first steam turbine.

4. The steam generation unit is a first steam generation unit that generates a first steam, The heat recovery boiler includes a second steam generation unit that generates a second steam at a pressure lower than the pressure of the first steam, The combined cycle power generation equipment according to claim 3, characterized in that the second steam is introduced into the reheat steam pipe between the steam outlet of the second steam turbine and the reheat section.

5. The heat recovery boiler includes a third steam generation unit that generates a third steam at a pressure lower than the pressure of the second steam, The combined cycle power generation equipment according to claim 2 or 4, characterized in that the third steam is introduced into a predetermined turbine stage of the third steam turbine.

6. The combined cycle power generation equipment according to claim 1 or 3, further comprising a condensate discharge system for removing the amount of water that has condensed from the steam generated in the combustor from the condensate generated in the condenser.

7. The combined cycle power generation equipment according to claim 1 or 3, further comprising a condensate supply system for supplying condensate generated in the condenser to the steam generation unit.

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