STEAM SUPPLY SYSTEM AND STEAM SUPPLY METHOD

Abstract

A control method is provided that, in a plant combining a GTCC and a CO2 capture plant, makes it possible to supply sufficient steam to the CO2 capture plant even during start-up of the GTCC. Specifically, a steam supply system is provided for supplying steam generated in a heat recovery steam generator to a CO2 capture plant that captures CO2 from exhaust gas emitted by a power generation plant including a gas turbine, the heat recovery steam generator, and a steam turbine. Medium-pressure steam generated in the heat recovery steam generator is supplied to the CO2 capture plant during start-up of the power generation plant.

Description

Technical area

[0001] The present disclosure relates to a steam supply system and a steam supply method for supplying steam to a CO2 capture system. The present disclosure claims priority based on Japanese Patent Application No. 2023-012809, filed in Japan on January 31, 2023, the contents of which are incorporated herein by reference. State of the art

[0002] A system combining a CO2 capture system with a gas turbine combined cycle (GTCC) has been provided. Patent Publication No. 1 discloses a configuration in which, in the system combining a GTCC and a CO2 capture system, an auxiliary heat exchanger for a CO2 capture system is prepared separately from a heat exchanger for a steam turbine, and steam required for the CO2 capture system is supplied. In this configuration, it is necessary to review a heat exchange design in an HRSG. Patent Publication No. 2 discloses a configuration in which a system combining a steam turbine and a CO2 capture system includes a pipe that supplies steam for driving a high-pressure turbine to a low-pressure turbine, and a take-off pipe that branches off from the pipe and supplies part of the steam for driving the high-pressure turbine to the CO2 capture system.It is assumed that if this configuration is applied to the plant where the GTCC and the CO2 capture plant are combined, it is possible to combine the CO2 capture plant with the existing GTCC configuration without significantly changing the configuration. Citation listPatent literature [PTL 1] International Publication No. WO2019 / 208416 [PTL 2] Japanese Patent No. 5968176 Summary of the invention Technical problem

[0003] In a case where the GTCC is operating at rated load, the CO2 capture system can be operated to achieve a target CO2 capture rate by supplying a portion of the steam to drive the steam turbine of the CO2 capture system. However, since a sufficient amount of steam is not generated during GTCC startup, steam cannot be supplied to the CO2 capture system, and there is a possibility that the CO2 capture rate will decrease. Although it is conceivable to provide an auxiliary boiler or the like to temporarily generate steam separately in a case where steam is insufficient, such as during plant startup, there are still problems related to costs, for example.

[0004] The present disclosure provides a steam supply system and a steam supply method capable of solving the problems described above. Solution to the problem

[0005] According to the present disclosure, a steam supply system is provided that supplies steam generated in a heat recovery steam generator to a CO2 capture system that captures CO2 from exhaust gas discharged from a power generation plant including a gas turbine, the heat recovery steam generator, and a steam turbine. The steam supply system comprises: a first system that supplies medium-pressure steam generated in the heat recovery steam generator to the CO2 capture system; a second system that takes a portion of low-pressure steam from a low-pressure system that supplies the low-pressure steam from the heat recovery steam generator to the steam turbine and supplies the portion of the low-pressure steam to the CO2 capture system; and a control device that performs control for supplying the steam to the CO2 capture system by the first system during startup of the power generation plant.

[0006] According to the present disclosure, there is provided a steam supply method comprising: supplying medium-pressure steam generated in a heat recovery steam generator to a CO2 capture system that captures CO2 from exhaust gas discharged from a power generation system including a gas turbine, the heat recovery steam generator, and a steam turbine, during start-up of the power generation system in a system including the power generation system and the CO2 capture system. Advantageous effects of the invention

[0007] According to the steam supply system and steam supply method described above, in the plant that combines the GTCC and the CO2 capture plant, it is possible to supply sufficient steam to the CO2 capture plant even during the GTCC start-up. Short description of the drawings Fig. 1 is a schematic diagram of a system according to each embodiment. Fig. 2 is a first view showing an example of a main part of a plant configuration according to a first embodiment. Fig. 3 is a second view showing an example of the main part of the system configuration according to the first embodiment. Fig. 4 is a diagram showing an example of a transition of state variables of a GTCC and a CO2 capture system during system startup according to the first embodiment. Fig. 5 is a time chart showing an example of switching control of a steam supply system according to a second embodiment. Fig. 6 is a flowchart showing an example of switching control of a steam supply system according to the second embodiment. Fig. 7 is a flowchart showing an example of switching control of a steam supply system according to a third embodiment. Fig. 8 is a flowchart showing an example of switching control of a steam supply system according to a fourth embodiment. Fig. 9 is a diagram showing an example of a main part of a plant configuration according to a fifth embodiment. Fig. 10 is a diagram showing an example of a hardware configuration of a startup control device according to each embodiment. Description of embodiments (overview)

[0008] A steam supply control for a CO2 capture system according to the present disclosure will be described below with reference to Fig. 1 to 10 described.

[0009] Fig. 1 shows a schematic configuration of a plant in which a GTCC (combined cycle power generation plant) and a CO2 capture plant are combined. A plant 100 includes a gas turbine 10, a heat recovery steam generator (HRSG) 20, a steam turbine 30, a CO2 capture plant 40, generators G1 and G2, and a control device 50. The gas turbine 10 is connected to a generator G1 and drives the generator G1. The steam turbine 30 is connected to a generator G2 and drives the generator G2. Exhaust gas discharged from the gas turbine 10 is fed to the HRSG 20, and after being used in the HRSG 20, it is fed to the CO2 capture plant 40. The HRSG 20 recovers heat from the exhaust gas, generates high-pressure steam, medium-pressure steam and low-pressure steam, supplies the steam to the steam turbine 30 and supplies the low-pressure steam to a regenerator 42 of the CO2 capture system 40.The HRSG 20 sends the exhaust gas after heat recovery to the CO2 capture system 40. The CO2 capture system 40 includes an absorber 41 and the regenerator 42 and extracts CO2 from the exhaust gas conveyed by the HRSG 20 by circulating an absorption liquid between the absorber 41 and the regenerator 42. CO2 extraction requires steam as a heat source, but the system 100 uses low-pressure steam supplied by the HRSG 20 as the heat source. The low-pressure steam used in the CO2 extraction process is condensed to become low-pressure hot water, and the generated low-pressure hot water is supplied from the CO2 capture system 40 to the HRSG 20. In such a configuration, the steam cannot be supplied to the CO2 capture system 40 until a sufficient amount of low-pressure steam is generated in the HRSG 20 after GTCC start-up.Therefore, in the present embodiment, a startup medium-pressure extraction system L10 that extracts a portion of medium-pressure steam from the HRSG 20 and supplies the portion of the medium-pressure steam to the CO2 capture system 40, and a control device 50 that controls switching the supply of steam to the CO2 capture system 40 between a system that supplies low-pressure steam to the CO2 capture system 40 and the startup medium-pressure extraction system L10 are provided. During GTCC startup, a portion of the medium-pressure steam, in which a sufficient amount of steam is generated earlier than the low-pressure steam, is controlled to be supplied to the CO2 capture system 40 through the startup medium-pressure extraction system L10. In this way, it is possible to supply the steam to the CO2 capture system 40 even during GTCC startup. <Erste Ausführungsform> (Configuration)

[0010] Fig. 2 is a first view showing an example of a main part of a plant configuration according to the first embodiment. The HRSG 20 provided in a rear stage of the gas turbine 10 includes a low-pressure economizer 21L, a medium-pressure economizer 21I, a high-pressure economizer 21H, a low-pressure evaporator 22L, a medium-pressure evaporator 22I, a high-pressure evaporator 22H, a low-pressure superheater 23L, a medium-pressure superheater 23I, a high-pressure superheater 23H, a reheater 24, a low-pressure drum 25L, a medium-pressure drum 25I, and a high-pressure drum 25H. The steam turbine 30 includes a high-pressure turbine 31, a medium-pressure turbine 32, and a low-pressure turbine 33. Low-pressure steam is supplied from the low-pressure superheater 23L to the low-pressure turbine 33 through a system L1.A system L2 leading to the CO2 capture system 40 is connected to the system L1, and a portion of the low-pressure steam supplied from the low-pressure superheater 23L is branched by the system L2 and supplied to the CO2 capture system 40 (regenerator 42). Further, on an upstream side of a branch point between the system L1 and the system L2 (upstream side in a steam flow direction, hereinafter simply referred to as an upstream side and a downstream side), a system L3 branching from the system L1 is provided, and a low-pressure turbine bypass valve V1 is provided in the system L3. During a period in which an amount of low-pressure steam generated during plant startup is small, a low-pressure turbine bypass valve V1 is open, and the low-pressure steam bypasses the low-pressure turbine 33 and is passed through the system L3 to a condenser (not shown).A pressure gauge P3 is provided at the branch point between the system L1 and the system L2, and a low-pressure steam control valve V2 is provided on the upstream side of the branch point where the pressure gauge P3 is provided in the system L1, and a CCP inlet pressure control valve V4 is provided on a downstream side (CCP indicates a CO2 capture system). A pressure gauge P2 that measures the pressure of the low-pressure steam supplied to the CO2 capture system 40 is provided on a downstream side of the system L2, and a low-pressure steam extraction valve V3 is provided between the pressure gauge P2 and the pressure gauge P3 in the system L2. For example, a temperature-reducing spray SP1 for adjusting (cooling) a temperature of the low-pressure steam to an appropriate temperature is provided in the vicinity of the position where the pressure gauge P2 is provided.

[0011] The high-pressure steam is supplied from the high-pressure superheater 23H to the high-pressure turbine 31 through a system L4. A high-pressure main steam control valve V6, which controls a flow rate of the high-pressure steam, is provided in the system L4. A system L5 is connected to the system L4, and a high-pressure turbine bypass valve V7 is provided in the system L5. When the high-pressure turbine bypass valve V7 is open, the high-pressure steam bypasses the high-pressure turbine 31 and flows to an outlet side of the intermediate-pressure superheater 23I through the system L5. The high-pressure steam supplied to the high-pressure turbine 31 is returned to the reheater 24 through a system L6. The system L6 is a system in which the system L5 and a system L11 converge on the outlet side of the intermediate-pressure superheater 23I.

[0012] Medium-pressure steam is supplied from the reheater 24 to the medium-pressure turbine 32 through a system L7. The pipe L7 is provided with a medium-pressure steam control valve V8 that regulates a flow rate of the medium-pressure steam. A system L8 is connected to the system L7, and a medium-pressure turbine bypass valve V9 is provided in the system L8. When the medium-pressure turbine bypass valve V9 is open, the medium-pressure steam bypasses the medium-pressure turbine 32 and flows through the system L8 to a condenser (not shown). The medium-pressure steam supplied to the medium-pressure turbine 32 is guided to a position where the pressure gauge P3 of the system L1 is provided through a system L9 (overflow pipe) and mixes with the low-pressure steam supplied to the low-pressure turbine 33 or the CO2 capture system 40. A pressure gauge P4 is provided upstream of the branch point between system L7 and system L8.At a position where the pressure gauge P4 is provided, a startup medium-pressure extraction system L10 is connected, which leads to the system L2, which is a steam supply system for the CO2 capture system 40. The startup medium-pressure extraction system L10 is provided with a startup medium-pressure steam pressure reducing valve V5, and the startup medium-pressure extraction system L10 is a system provided to supply steam to the CO2 capture system 40 during GTCC startup. A pressure gauge P1 is provided on a downstream side of the startup medium-pressure steam pressure reducing valve V5 in the startup medium-pressure extraction system L10. A temperature-reducing spray SP2 for adjusting (cooling) a temperature of the medium-pressure steam to an appropriate temperature is provided in the vicinity of the position where the pressure gauge P1 is provided. The start-up medium pressure extraction system L10 is connected to the system L2 at a supply unit C1.The steam generated by the HRSG 20 is fed to the CO2 capture system 40 via the supply unit C1.

[0013] The control device 50 detects values ​​measured by the pressure gauges P1 to P4 and controls opening degrees of the low-pressure turbine bypass valve V1, the low-pressure steam control valve V2, the low-pressure steam extraction valve V3, the CCP inlet pressure control valve V4, the start-up medium-pressure steam pressure reducing valve V5, the high-pressure main steam control valve V6, the high-pressure turbine bypass valve V7, the medium-pressure steam control valve V8 and the medium-pressure turbine bypass valve V9.

[0014] In the Fig. In the configuration example shown in Figure 2, an example is shown in which the start-up medium-pressure extraction system L10 is provided to connect the outlet of the reheater 24 and the system L2, which is a steam supply system for the CO2 capture system 40. As shown in Fig. 3, the start-up medium pressure extraction system L10 can also be provided to connect the outlet side of the medium pressure superheater 23I and the system L2.

[0015] Fig. 3 is a second view showing an example of a main part of a system configuration according to the first embodiment. In the Fig. In the configuration example shown in Figure 3, the pressure gauge P4 is provided at the converging point of the system L11 (discharge system of the medium-pressure steam generated in the medium-pressure drum 25I) on the outlet side of the medium-pressure superheater 23I, the system L5, and the system L6, instead of the system L7 that supplies the medium-pressure steam to the medium-pressure turbine 32. The start-up medium-pressure extraction system L10 is provided such that the converging point and the system L2 are connected to each other at the supply unit C1.

[0016] As described above, during GTCC start-up, insufficient steam is generated to be supplied to the CO2 capture system 40, and there is a possibility that the CO2 capture rate will decrease. As shown in a graph 404 of Fig. 4, it takes time to ensure a sufficient steam flow rate for the low-pressure steam after GTCC startup. Therefore, in the prior art, the medium-pressure steam released to the outside of the system via a condenser (not shown) through a turbine bypass during GTCC startup is supplied to the CO2 capture system 40 through the startup medium-pressure extraction system L10. In this way, the steam flow rate supplied to the CO2 capture system 40 during GTCC startup is ensured. As shown in a graph 403 of Fig. As shown in Figure 4, in the case of medium-pressure steam, a sufficient amount of steam is generated in the HRSG 20 earlier than in the case of low-pressure steam. By supplying this to the CO2 capture system 40, it is expected that the CO2 capture rate can be improved during GTCC start-up. Fig. 2 and Fig. 3 is a modification in which a piping system is added to the outside of the heat exchanger of the HRSG 20, it is not necessary to change the design of the HRSG 20 itself, and it is possible to prevent an increase in the design cost or the manufacturing cost of the HRSG 20.

[0017] Fig. Figure 4 is a diagram showing an example of a transition of state variables of a GTCC and a CO2 capture plant during plant start-up. The vertical axis of each graph in Fig. 4 represents the magnitude of each state variable, and the horizontal axis represents time. The same position on the horizontal axis represents the same time. A graph 401 shows a transition of the rotational speed of the gas turbine 10. When ignition is performed on the gas turbine 10 and the GTCC is started, the rotational speed of the gas turbine 10 increases. A graph 402 shows a transition of the power of the gas turbine 10. When the rotational speed of the gas turbine 10 reaches a predetermined value, the gas turbine 10 is connected (integrated) with the generator G1. Upon integration with the gas turbine 10, the generator G1 is driven, thereby increasing the power. Thereafter, when steam is generated in the HRSG 20, when the rotational speed of the steam turbine 30 increases and the steam turbine 30 is connected (integrated) with the generator G2, the power of the gas turbine 10 and the steam turbine 30 is further increased.Graph 403 shows a transition of the low-pressure steam flow rate, and graph 404 shows a transition of the medium-pressure steam flow rate. As shown in the drawing, after the ignition of the gas turbine 10, the low-pressure steam flow rate and the medium-pressure steam flow rate begin to increase after a while, but the medium-pressure steam flow rate increases faster than the low-pressure steam flow rate. By utilizing this characteristic, the medium-pressure steam is supplied to the CO2 capture system 40 through the startup medium-pressure extraction system L10, so that the required flow rate can be ensured early after the GTCC startup in the CO2 capture system 40. Graph 405 shows a transition of the exhaust flow rate discharged from the gas turbine 10.A graph 406 shows a transition in the flow rate of the absorption liquid at the CO2 capture system 40, and a graph 407 shows a transition in the required steam flow rate at the CO2 capture system 40. The exhaust gas flow rate also increases as the power of the gas turbine 10 increases. The flow rate of the absorption liquid and the required amount of steam increase as the flow rate of the exhaust gas from the gas turbine 10 increases. (Overview of tax procedures)

[0018] During GTCC start-up, medium pressure steam is supplied from the reheater 24 (configuration in Fig. 2) or the outlet side of the medium pressure superheater 23I (configuration in Fig. 3) by opening the start-up medium-pressure steam pressure reducing valve V5 provided in the start-up medium-pressure extraction system L10 and supplying it to the CO2 capture system 40. On the other hand, after the GTCC start-up is completed, the start-up medium-pressure steam pressure reducing valve V5 is closed, the start-up medium-pressure extraction system L10 is not used, and instead of the start-up medium-pressure extraction system L10, the low-pressure steam is supplied to the L2 system through the L1 system, and the low-pressure steam is supplied to the CO2 capture system 40. Since the low-pressure steam must be supplied to the CO2 capture system 40, the pressure of the medium-pressure steam in the start-up medium-pressure extraction system L10 is reduced to the low pressure by controlling the opening degree of the start-up medium-pressure steam pressure reducing valve V5 during GTCC start-up.For example, a setpoint (as an example, a constant pressure) of the pressure of the steam supplied to the CO2 capture system 40 is set, and the opening degree of the start-up medium-pressure steam pressure reducing valve V5 is feedback-controlled so that the pressure measured by the pressure gauge P1 becomes the setpoint. Since the medium-pressure steam has a relatively high temperature, the temperature is reduced by spraying water from the temperature-reducing spray SP2 shortly before the medium-pressure steam reaches the supply unit C1 for the CO2 capture system 40, and the medium-pressure steam is merged with the supply unit C1.After the GTCC startup is completed and the low-pressure steam extraction system (the low-pressure steam extraction system refers to a system that extracts low-pressure steam from the L1 system and supplies the steam to the CO2 capture system 40 through the L2 system) is switched, by controlling the opening degree of the CCP inlet pressure control valve V4 provided on the inlet side of the low-pressure turbine 33, the pressure of the steam supplied to the L2 system is maintained at the set value, and the CO2 capture system 40 can stably capture CO2. Details of the control for switching between the startup medium-pressure extraction system L10 and the low-pressure steam extraction system will be described in the second to fourth embodiments. (Effects)

[0019] As described above, the startup medium-pressure extraction system L10 is provided, and during GTCC startup, steam is supplied to the CO2 capture system 40 via the startup medium-pressure extraction system L10. In this way, the amount of steam required for CO2 capture can be ensured. Accordingly, in the CO2 capture system 40, the CO2 capture rate can be maintained high even during GTCC startup. In the GTCC in the prior art, there is a case where the auxiliary boiler itself is provided. However, it is not necessary to increase the capacity of the auxiliary boiler for the CO2 capture system 40. Regarding the provision of the startup medium-pressure extraction system L10, the HRSG 20 can have the same design as in the case of the stand-alone GTCC, and an increase in the design cost or manufacturing cost can be prevented. <Zweite Ausführungsform>

[0020] In the second embodiment, an example of control for switching between the start-up medium-pressure extraction system L10 used during start-up and the low-pressure steam extraction system used during normal operation will be explained with reference to Fig. 5 and Fig. 6 described. Fig. Figure 5 shows an example of a time chart of a state variable or valve opening degree related to the switching control of the steam supply system. The vertical axis of each graph in Fig. 5 represents the magnitude of each state variable or valve opening degree, and the horizontal axis represents time. The same position on the horizontal axis represents the same time. During GTCC startup, each event of ST ventilation, ST integration, the start of normal steam system use, and system switching occurs. ST ventilation serves to close the low-pressure turbine bypass valve V1, the intermediate-pressure turbine bypass valve V9, and the high-pressure turbine bypass valve V7, and start the supply of the low-pressure steam, intermediate-pressure steam, and high-pressure steam generated in the HRSG 20 to the steam turbine 30. ST integration serves to connect the steam turbine to the generator G2. The start of normal steam system use means that the supply of low-pressure steam from the low-pressure steam extraction system to the CO2 capture system 40 is started.As described below, there is a period in which both systems are used together, from the start-up medium-pressure extraction system L10 to the low-pressure steam extraction system, until complete switching occurs. System switching involves completely switching from the start-up medium-pressure extraction system L10 to the low-pressure steam extraction system by fully opening the low-pressure steam extraction valve V3.

[0021] A graph 501 shows a transition of the rotational speed (GT speed) of the gas turbine 10, and a graph 502 shows a transition of the rotational speed (ST speed) of the steam turbine 30. As shown in the drawing, the steam turbine 30 is started with a delay after the gas turbine 10, and the rotational speed of the steam turbine 30 gradually increases due to ST ventilation. When the rotational speed of the steam turbine 30 reaches a predetermined value, ST integration is performed. A graph 503 shows a transition of the opening degree of the low-pressure steam extraction valve V3. The low-pressure steam extraction valve V3 is fully closed before the start of use of the normal steam system and is controlled to increase the opening degree at the time of start of use of the normal steam system and to be fully open at the time of system switching. A graph 504 shows a transition of the opening degree of the medium-pressure steam control valve V8.The medium-pressure steam control valve V8 is open at the time of ST venting and then gradually opens and finally opens fully. A graph 505 shows a transition of the opening degree of the CCP inlet pressure control valve V4. The CCP inlet pressure control valve V4 is set to a constant opening degree until the system switching operation is performed. For example, the opening degree of the CCP inlet pressure control valve V4 is set to be fully open or partially open so that steam can flow to the low-pressure turbine 33. After the system switching, the control device 50 controls the opening degree of the CCP inlet pressure control valve V4 so that the pressure measured by the pressure gauge P2 becomes constant (setpoint). A graph 506 shows a transition of the opening degree of the start-up medium-pressure steam control valve V5.From immediately after GTCC startup until ST integration, the low-pressure turbine bypass valve V1 is open to bypass the low-pressure steam. Since the steam control valve V2 is not sufficiently open, the steam from the low-pressure system V1 cannot be used. Therefore, the low-pressure steam extraction valve V3 is fully closed (Graph 503), and the startup medium-pressure steam control valve V5 is open to supply all steam to be supplied to the CO2 capture system 40 through the startup medium-pressure extraction system L10. The opening degree of the startup medium-pressure steam control valve V5 is controlled so that the pressure measured by the pressure gauge P1 remains constant until the system switchover occurs, and the startup medium-pressure steam control valve V5 is fully closed after the system switchover.The control device 50 controls the opening degree of the start-up medium-pressure steam control valve V5 through feedback control, such as PID control, for example, to maintain the value of the pressure gauge P1 at the setpoint pressure. A graph 507 shows a transition of the pressure measured by the pressure gauge P2, and a graph 508 shows a transition of the pressure measured by the pressure gauge P3. Before the ST integration, the pressure of the pressure gauge P2 is high and the pressure of the pressure gauge P3 is low. During the ST integration, as steam begins to flow through the system L1 and the system L9 (overflow pipe), the pressure of the pressure gauge P3 gradually increases, and the pressure of the pressure gauge P2 decreases. When the pressure of the pressure gauge P3 exceeds the pressure of the pressure gauge P2, the low-pressure steam extraction valve V3 is opened and the supply of low-pressure steam to the CO2 separation system is started (start of use of the normal steam system).After the low-pressure steam extraction valve V3 is opened, the pressure control of the start-up medium-pressure steam pressure reducing valve V5 continues, but the valve is controlled in such a way that it closes as the inflow of low-pressure steam increases. When the low-pressure steam extraction valve V3 is fully open, the start-up medium-pressure steam pressure reducing valve V5 is fully closed (graph 506). When the low-pressure steam extraction valve V3 is fully open, the control device 50 adjusts the opening degree of the CCP inlet pressure control valve V4 so that the pressure of the pressure gauge P2 reaches the setpoint (graph 505). (Operation)

[0022] The flow of the switching control of the steam supply system according to the second embodiment will be explained with reference to Fig. 6. First, the control device 50 fully closes the low-pressure steam extraction valve V3, sets the opening degree of the CCP inlet pressure regulating valve V4 to a predetermined fixed opening degree, and controls the opening degree of the start-up medium-pressure steam pressure reducing valve V5 so that the pressure measured by the pressure gauge P1 becomes a predetermined set value (step S1). In this state, GTCC start-up is initiated. The control device 50 determines whether or not the pressure measured by the pressure gauge P3 exceeds the pressure measured by the pressure gauge P2 while monitoring the measured values ​​of the pressure gauges P1 to P4 (step S4). In a case where the pressure measured by the pressure gauge P3 is equal to or less than the pressure measured by the pressure gauge P2 (step S4; No), the control device 50 proceeds to step S1.If the pressure measured by the pressure gauge P3 exceeds the pressure measured by the pressure gauge P2 (step S4; Yes), the control device 50 controls the opening degree of the low-pressure steam extraction valve V3 so that it is fully open (step S5). The control device 50 opens the low-pressure steam extraction valve V3 in a fully closed state, for example, at a constant speed. The control device 50 determines whether the low-pressure steam extraction valve V3 is fully open or not (step S6). If the low-pressure steam extraction valve V3 is fully open (step S6; Yes), the control device 50 controls the start-up medium-pressure steam pressure reducing valve V5 so that it is fully closed (step S7). The control device 50 gradually closes the start-up medium-pressure steam pressure reducing valve V5 to fully close the start-up medium-pressure steam pressure reducing valve V5.In parallel with step S7, the control device 50 controls the opening degree of the CCP inlet pressure control valve V4 so that the pressure measured by the pressure gauge P2 becomes a predetermined target value (step S8). (Effects)

[0023] According to the second embodiment, the system for supplying steam to the CO2 capture system 40 can be switched from the startup medium-pressure extraction system L10 to the low-pressure steam extraction system. The steam supply pressure is maintained even during the switching, and a temporary decrease in the steam supply rate can be prevented. <Dritte Ausführungsform>

[0024] In the control described in the second embodiment, the low-pressure steam extraction valve V3 is opened in a case where the pressure before and after the low-pressure steam extraction valve V3 satisfies a condition of pressure measured by the pressure gauge P3 > pressure measured by the pressure gauge P2. In the GTCC control in the related art, in order to regulate the pressure on the inlet side of the low-pressure turbine 33, there is a case where the low-pressure turbine bypass valve V1 is opened even after the ST integration. In this case, the steam escapes through the turbine bypass, the pressure measured by the pressure gauge P3 does not increase, and the system switching may not be completed because the above condition is not satisfied.Therefore, in the third embodiment, a pressure control set value of the low-pressure turbine bypass valve V1 after the ST integration is set to at least a value higher than a CCP inlet pressure set value, that is, a set value (a set value related to the pressure measured by the pressure gauge P1) of the pressure control of the start-up medium-pressure steam control valve V5. That is, in order to maintain a state where the pressure around the low-pressure turbine bypass valve V1 is high, the low-pressure turbine bypass valve V1 is in a state where it is not over-opened. Accordingly, even after the ST integration, a certain amount or more of low-pressure steam flows through the control valve V2, the pressure measured by the pressure gauge P3 increases, and the condition of pressure of the pressure gauge P3 > pressure of the pressure gauge P2 is satisfied. (Operation)

[0025] The flow of switching control of the steam supply system according to the third embodiment will be explained with reference to Fig. 7. First, the control device 50 fully closes the low-pressure steam extraction valve V3, sets the opening degree of the CCP inlet pressure control valve V4 to a predetermined fixed opening degree, and controls the opening degree of the start-up medium-pressure steam pressure reducing valve V5 so that the pressure measured by the pressure gauge P1 becomes a predetermined set value (step S1). In this state, GTCC start-up is initiated. Next, the control device 50 determines whether the process is a process in which the ST integration is completed or not (step S2). Until the ST integration is completed, the control device 50 continues control at step S1. If the ST integration is completed (step S2; Yes), the control device 50 switches a pressure control set value of the low-pressure turbine bypass valve V1 to a value higher than the CCP inlet pressure set value (step S3).The control device 50 controls the opening degree of the low-pressure turbine bypass valve V1 so that the pressure of the low-pressure steam flowing through the low-pressure turbine bypass valve V1 becomes a predetermined set value set to be higher than the set value set for the pressure measured by the pressure gauge P1.

[0026] Next, the control device 50 determines whether the pressure measured by the pressure gauge P3 exceeds the pressure measured by the pressure gauge P2 while monitoring the values ​​measured by the pressure gauges P1 to P4 (step S4). If the pressure measured by the pressure gauge P3 is equal to or less than the pressure measured by the pressure gauge P2 (step S4; No), the control device 50 continues control at step S3.When the pressure measured by the pressure gauge P3 exceeds the pressure measured by the pressure gauge P2 (step S4; Yes), the control device 50 controls the opening degree of the low-pressure steam extraction valve V3 to be fully open (step S5), and when the low-pressure steam extraction valve V3 is fully open (step S6; Yes), the control device 50 controls the start-up medium-pressure steam pressure reducing valve V5 to be fully closed (step S7), and controls the opening degree of the CCP inlet pressure regulating valve V4 so that the pressure measured by the pressure gauge P2 becomes a predetermined set value (step S8).

[0027] The control of the third embodiment is not limited to the Fig. 7. For example, regardless of an event such as ST integration, the pressure control set point of the low-pressure turbine bypass valve V1 may be initially set to a value higher than the CCP inlet pressure set point (set point with respect to P1). Alternatively, instead of switching the pressure control set point of the low-pressure turbine bypass valve V1, it is also conceivable to completely close the low-pressure turbine bypass valve V1. In a case where there is no limitation of the pressure on the inlet side of the low-pressure turbine 33 (the pressure may be high), after the ST integration is completed, the low-pressure turbine bypass valve V1 is completely closed. In this way, it is possible to solve a problem in which switching is not completed because the condition of pressure of pressure gauge P3 > pressure of pressure gauge P2 is not satisfied. (Effects)

[0028] According to the third embodiment, in addition to the effect of the second embodiment, the switching of the steam supply system is reliably completed by promoting the increase of the pressure measured by the pressure gauge P3. <Vierte Ausführungsform>

[0029] In the fourth embodiment, a withdrawal start-up condition of the start-up medium-pressure steam pressure reducing valve V5 is set, and when this condition is satisfied, the start-up medium-pressure steam pressure reducing valve V5 is opened, and the opening degree control based on the pressure measured by the pressure gauge P1 is started. (Operation)

[0030] The flow of switching control of the steam supply system according to the fourth embodiment will be explained with reference to Fig. 8 described.

[0031] First, the control device 50 fully closes the low-pressure steam extraction valve V3, sets the opening degree of the CCP inlet pressure regulating valve V4 to a predetermined fixed opening degree, and fully closes the start-up medium-pressure steam pressure reducing valve V5 (step S1a). In this state, GTCC start-up is initiated. The control device 50 determines whether or not the pressure measured by the pressure gauge P4 exceeds the pressure measured by the pressure gauge P1 while monitoring the values ​​measured by the pressure gauges P1 to P4 (step S2a). This condition is not met during GTCC start-up, and if steam generation in the medium-pressure drum 25I or the like is active, this condition is met. In a case where the pressure measured by the pressure gauge P4 is equal to or less than the pressure measured by the pressure gauge P1 (step S2a; No), the control device 50 proceeds to step S1a.If the pressure measured by the pressure gauge P4 exceeds the pressure measured by the pressure gauge P1 (step S2a; Yes), the control device 50 opens the start-up medium-pressure steam pressure reducing valve V5 and controls the opening degree of the start-up medium-pressure steam pressure reducing valve V5 so that the pressure measured by the pressure gauge P1 becomes a predetermined set value (step S3a). By opening the start-up medium-pressure steam pressure reducing valve V5 after the pressure on the upstream side of the start-up medium-pressure steam pressure reducing valve V5 becomes higher than the pressure on the downstream side, backflow or the like can be prevented.

[0032] Next, the control device 50 determines whether the pressure measured by the pressure gauge P3 exceeds the pressure measured by the pressure gauge P2 (step S4). If the pressure measured by the pressure gauge P3 is equal to or less than the pressure measured by the pressure gauge P2 (step S4; No), the control device 50 continues control at step S3.When the pressure measured by the pressure gauge P3 exceeds the pressure measured by the pressure gauge P2 (step S4; Yes), the control device 50 controls the opening degree of the low-pressure steam extraction valve V3 to be fully open (step S5), and when the low-pressure steam extraction valve V3 is fully open (step S6; Yes), the control device 50 controls the start-up medium-pressure steam pressure reducing valve V5 to be fully closed (step S7), and controls the opening degree of the CCP inlet pressure regulating valve V4 so that the pressure measured by the pressure gauge P2 becomes a predetermined set value (step S8). (Effects)

[0033] According to the fourth embodiment, extraction is started after the pressure of a medium-pressure steam supply source has been sufficiently increased, so that the backflow event can be prevented. In the above description, a case of combining with the control of the second embodiment was described as an example. However, the fourth embodiment can be combined with the third embodiment. <Fünfte Ausführungsform>

[0034] In the fifth embodiment, the position where the start-up medium pressure extraction system L10 and the system L2 are joined is on an upstream side of the supply unit C1 in Fig. 2 and Fig. 3 is provided. Fig. Figure 9 shows a system diagram of a section where the start-up medium-pressure extraction system L10 and the system L2 are combined. As shown in the drawing, the start-up medium-pressure extraction system L10 is connected at a position where the pressure gauge P2 is provided. In the case of a configuration of Fig. 2 and Fig. 3, it is necessary to provide the temperature reducing sprays SP1 and SP2 in the system L2 and the system L3, respectively. In a case of the Fig. However, in the configuration shown in Figure 9, it is possible, for example, by providing a temperature-reducing spray SP3 in the supply unit C1, to reduce the temperature of the steam supplied to the CO2 separation system 40. (Effects)

[0035] According to the fifth embodiment, the number of spray systems can be reduced from two to one, and the cost of the pipe or valve can be reduced. The configuration according to the fifth embodiment can be combined with any of the controllers of the second to fourth embodiments.

[0036] As described above, according to the first to fifth embodiments, in the plant in which the GTCC and the CO2 capture plant are combined, sufficient steam can be supplied to the CO2 capture plant even during GTCC start-up.

[0037] Fig.10 is a diagram showing an example of a hardware configuration of the control device according to each embodiment. A computer 900 includes a CPU 901, a main storage device 902, an auxiliary storage device 903, an input and output interface 904, and a communication interface 905. The above-described control device 50 is implemented in the computer 900. Each of the above-described functions is stored in the form of a program in the auxiliary storage device 903. The CPU 901 reads the program from the auxiliary storage device 903, expands the program in the main storage device 902, and executes the above-described processing according to the program. The CPU 901 allocates a storage area in the main storage device 902 according to the program. The CPU 901 allocates a storage area for storing data to be processed in the auxiliary storage device 903 according to the program.

[0038] By recording a program for realizing all or some of the functions of the control device 50 on a computer-readable recording medium, reading the program recorded on the recording medium into a computer system, and executing the read-in program, the processes are performed by each functional unit. The "computer system" here includes an operating system and hardware such as peripheral devices. The "computer system" also includes a homepage provision environment (or display environment) in a case where a WWW system is used. The "computer-readable recording medium" refers to a portable medium such as a CD, DVD, or USB, or to a storage device such as a hard disk built into the computer system.In a case where the program is distributed to the computer 900 via a communication line, the computer 900 to which the program was distributed can expand the program in the main storage device 902 and execute the above-described processing. The above-described program can serve to realize part of the above functions and can further realize the above-described functions in combination with a program already recorded in the computer system.

[0039] As described above, although some embodiments have been described according to the present disclosure, all of these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included within the scope of the invention described in the claims and the equivalent scope thereof, as well as within the scope and gist of the invention. <Zusätzliche Hinweise>

[0040] The steam supply system and the steam supply method described in each embodiment are understood, for example, as follows. (1) A steam supply system according to a first aspect is a steam supply system that supplies steam generated in a heat recovery steam generator to a CO2 capture system 40 that captures CO2 from exhaust gas discharged from a power generation plant (GTCC) including a gas turbine 10, the heat recovery steam generator (HRSG 20), and a steam turbine 30. The steam supply system comprises a first system (L10) that supplies medium-pressure steam generated in the heat recovery steam generator to the CO2 capture system; a second system (L2) that takes part of low-pressure steam from a low-pressure system (L1) that supplies the low-pressure steam from the heat recovery steam generator to the steam turbine and supplies the part of the low-pressure steam to the CO2 capture system; and a control device 50 that performs control for supplying the steam to the CO2 capture system by the first system during start-up of the power generation system.

[0041] Accordingly, in a plant where the GTCC and the CO2 capture plant are combined, sufficient steam can be supplied to the CO2 capture plant even during GTCC start-up. (2) The steam supply system according to a second aspect is the steam supply system of (1), wherein the control device 50 performs control for supplying the steam to the CO2 capture system through the second system when the start-up of the power generation plant is completed.

[0042] Accordingly, after a sufficient amount of low-pressure steam has been generated, the low-pressure steam required for the CO2 capture system can be supplied. (3) The steam supply system according to a third aspect is the steam supply system of (1) to (2), wherein the second system is provided with a bleed valve (V3) that is fully closed at a time point from the start of startup of the power generation plant, and the control device opens the bleed valve for a predetermined time until the bleed valve is fully opened when a pressure (P3) at a connection position between the low-pressure system (L1) and the second system (L2) exceeds a pressure (P2) on a downstream side of the bleed valve (V3) that is fully opened in a steam flow direction in the second system.

[0043] In this way, the low-pressure steam is fed to the CO2 capture plant without backflow. (4) The steam supply system according to a fourth aspect is the steam supply system of (1) to (3), wherein the control device, when the extraction valve is fully opened, fully closes a pressure reducing valve provided in the first system.

[0044] In this way, the system switchover from the start-up medium-pressure extraction system to the low-pressure steam extraction system is completed. (5) The steam supply system according to a fifth aspect is the steam supply system of (3), wherein a pressure regulating valve for regulating a pressure of low-pressure steam tapped by the second system is provided on a downstream side in a steam flow direction from the connection position with the second system in the low-pressure system, and the control device controls an opening degree of the pressure regulating valve so that the pressure on the downstream side of the tap valve becomes a predetermined set value.

[0045] In this way, the pressure of the steam required for supply to the CO2 capture plant can be maintained (during normal operation). (6) The steam supply system according to a sixth aspect is the steam supply system of (1) to (5), wherein a pressure reducing valve is provided in the first system, and the control device controls an opening degree of the pressure reducing valve so that a pressure of the medium-pressure steam is reduced to a predetermined target value.

[0046] In this way, the pressure of the steam required for supply to the CO2 capture plant can be maintained (during GTCC start-up). (7) The steam supply system according to a seventh aspect is the steam supply system of (6), wherein the low-pressure system is connected to a bypass system that discharges the low-pressure steam by bypassing the steam turbine, and the bypass system is provided with a bypass valve, and the control device sets a target value of a pressure at a position of the bypass valve, after integration of the steam turbine, to a value higher than the predetermined target value and controls an opening degree of the bypass valve so that the pressure at the position of the bypass valve reaches the set value.

[0047] Accordingly, even in a case where an operation is performed to open the low-pressure turbine bypass valve after ST integration, it is possible to complete the system switching from the start-up medium-pressure extraction system to the low-pressure steam extraction system. (8) The steam supply system according to an eighth aspect is the steam supply system of (5) and (6), wherein the pressure reducing valve is fully closed when the startup of the power generation plant is started, and the control device opens the pressure reducing valve and starts controlling the opening degree of the pressure reducing valve based on the predetermined target value when a pressure on an upstream side of the pressure reducing valve in a steam flow direction exceeds a pressure on a downstream side.

[0048] By starting the extraction after the pressure of the medium pressure steam supply source has been sufficiently increased, it is possible to prevent the backflow event. (9) The steam supply system according to a ninth aspect is the steam supply system of (1) to (8), wherein a spray for reducing a temperature of the medium-pressure steam is provided in the first system.

[0049] In this way, the temperature of the medium pressure steam can be reduced at a relatively high temperature. (10) The steam supply system according to a tenth aspect is the steam supply system of (1) to (8), the system further comprising a third system that connects the first system and the second system at a predetermined position and supplies steam supplied by the first system and / or the second system to the CO2 capture system, wherein a spray for reducing a temperature of the steam is provided in the third system.

[0050] In this way, the low pressure steam temperature reduction spray and the medium pressure steam temperature reduction spray can be combined into one, resulting in cost reduction. (11) A steam supply method according to an eleventh aspect comprises supplying medium-pressure steam generated in a heat recovery steam generator to a CO2 capture system that captures CO2 from exhaust gas discharged from a power generation plant including a gas turbine, the heat recovery steam generator, and a steam turbine, during start-up of the power generation plant in a plant including the power generation plant and the CO2 capture system. Industrial Applicability

[0051] According to the steam supply system and steam supply method described above, in the plant that combines the GTCC and the CO2 capture plant, it is possible to supply sufficient steam to the CO2 capture plant even during the GTCC start-up. List of reference symbols 100 system 10 gas turbines 20 EDSG 21L low-pressure economizer 21I medium-pressure economizer 21H high-pressure economizer 22L low pressure evaporator 22I medium pressure evaporator 22H high pressure evaporator 23L low-pressure superheater 23I medium-pressure superheater 23H high pressure superheater 24 reheaters 25L low-pressure drum 25I medium pressure drum 25H high-pressure drum 30 steam turbines 31 High-pressure turbine 32 medium-pressure turbine 33 Low-pressure turbine 40 CO2 capture plant 50 Control device G1, G2 generator P1 to P4 pressure gauges V1 Low-pressure turbine bypass valve V2 low-pressure steam control valve V3 Low-pressure steam extraction valve V4 CCP inlet pressure control valve V5 start-up medium-pressure steam pressure reducing valve V6 High pressure main steam control valve V7 High-pressure turbine bypass valve V8 medium pressure steam control valve V9 medium-pressure turbine bypass valve L1 to L11 system 900 computers 901 CPU 902 Main storage device 903 Auxiliary storage device 904 Input and output interface 905 Communication interface QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-012809

[0001] WO 2019 / 208416

[0002] JP 5968176

[0002]

Claims

[1] A steam supply system that supplies steam generated in a heat recovery steam generator to a CO2 capture plant that captures CO2 from exhaust gas emitted from a power generation plant that includes a gas turbine, the heat recovery steam generator and a steam turbine, the steam supply system comprising: a first system that supplies medium-pressure steam generated in the heat recovery steam generator to the CO2 capture plant; a second system that extracts a portion of low-pressure steam from a low-pressure system that supplies the low-pressure steam from the heat recovery steam generator to the steam turbine and supplies the portion of the low-pressure steam to the CO2 capture plant; and a control device that performs control for supplying the steam to the CO2 capture system by the first system during start-up of the power generation system. [2] The steam supply system according to claim 1, wherein the control device performs control for supplying the steam to the CO2 capture system through the second system when the start-up of the power generation system is completed. [3] Steam supply system according to claim 2, wherein the second system is provided with a bleed valve which is completely closed at a time from the start of the power generation plant, and the control device opens the bleed valve for a predetermined time until the bleed valve is fully opened when a pressure at a connection position between the low-pressure system and the second system exceeds a pressure on a downstream side of the bleed valve in a steam flow direction in the second system. [4] A steam supply system according to claim 3, wherein, when the extraction valve is fully opened, the control device fully closes a pressure reducing valve provided in the first system. [5] Steam supply system according to claim 3, wherein a pressure control valve for controlling a pressure of low-pressure steam taken out by the second system is provided on a downstream side in a steam flow direction from the connection position with the second system in the low-pressure system, and the control device controls an opening degree of the pressure regulating valve so that the pressure on the downstream side of the extraction valve becomes a predetermined target value. [6] Steam supply system according to claim 1 or 2, wherein a pressure reducing valve is provided in the first system, and the control device controls an opening degree of the pressure reducing valve so that a pressure of the medium-pressure steam is reduced to a predetermined target value. [7] Steam supply system according to claim 6, wherein the low-pressure system is connected to a bypass system which releases the low-pressure steam by bypassing the steam turbine, and the bypass system is provided with a bypass valve, and the control device sets a target value of a pressure at a position of the bypass valve after integration of the steam turbine to a value higher than the predetermined target value and controls an opening degree of the bypass valve so that the pressure at the position of the bypass valve reaches the set value. [8] Steam supply system according to claim 6, wherein the pressure reducing valve is fully closed when the power generation plant is started, and the control device opens the pressure reducing valve and starts to control the opening degree of the pressure reducing valve based on the predetermined set value when a pressure on an upstream side of the pressure reducing valve in a steam flow direction exceeds a pressure on a downstream side. [9] A steam supply system according to claim 1 or 2, wherein a spray for reducing a temperature of the medium pressure steam is provided in the first system. [10] Steam supply system according to claim 1 or 2, further comprising: a third system connecting the first system and the second system at a predetermined position and supplying steam supplied by the first system and / or the second system to the CO2 capture system, wherein a spray is provided for reducing a temperature of the steam in the third system. [11] A steam supply process comprising: Supplying medium-pressure steam generated in a heat recovery steam generator to a CO2 capture plant that captures CO2 from exhaust gas emitted from a power generation plant including a gas turbine, the heat recovery steam generator and a steam turbine, during start-up of the power generation plant in a plant including the power generation plant and the CO2 capture plant.

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