Fuel heating method and fuel heating system

Abstract

To reduce water hammer that might occur in a flow passage of a heating medium when starting supply of the heating medium for heating fuel to be supplied to a combustor of a gas turbine at start of a gas turbine power plant.SOLUTION: A gas turbine power plant includes: a fuel heater; a cooler for cooling a heating medium after heating fuel by using the fuel heater; a first flow passage that connects the fuel heater to the cooler and in which the heating medium after heating the fuel by using the fuel heater can flow; a second flow passage that is connected to the cooler and in which the heating medium after cooled by the cooler can flow; a first on-off valve provided in the first flow passage; and a second on-off valve provided in the second flow passage. In a fuel heating method according to one embodiment, when heating of the fuel by using the fuel heater is started, a step of opening the second on-off valve and a step of opening the first on-off valve following execution of the step of opening the second on-off valve are executed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a fuel heating method and a fuel heating system for heating fuel supplied to a combustor of a gas turbine. [Background technology]

[0002] 2. Description of the Related Art There is known a gas turbine plant including a gas turbine and a heat recovery boiler that generates steam by exchanging heat between exhaust gas discharged from the gas turbine and water. A gas turbine includes an air compressor that compresses outside air to generate compressed air, a number of combustors that burn fuel in the compressed air to generate combustion gas, and a turbine driven by the combustion gas (see, for example, Patent Document 1). For example, in a gas turbine plant described in Patent Document 1, fuel is heated with water supplied from a heat recovery steam generator. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-40619 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the gas turbine plant described in the above-mentioned Patent Document 1, the fuel can be heated by the fuel heater using a heating medium. In the gas turbine plant described in the above-mentioned Patent Document 1, this heating medium is, for example, feed water from a heat recovery boiler. The feed water after the fuel is heated by the fuel heater is returned to the heat recovery boiler again. If the temperature of the feed water is relatively high even after the fuel is heated by the fuel heater, the feed water after the fuel is heated by the fuel heater may be cooled by a cooler.

[0005] In a configuration in which the feedwater after heating the fuel in the fuel heater is cooled by a cooler, open / close valves may be provided in the flow paths upstream and downstream of the cooler to prohibit the feedwater from flowing through the cooler during periods when the gas turbine plant is shut down. In this case, if the temperature of the feedwater drops while the gas turbine plant is stopped and the two on-off valves are closed, an air layer may be generated in the flow path between the two on-off valves, which may cause water hammer in the feedwater flow path when the flow of the feedwater is resumed the next time the gas turbine plant is started up.

[0006] In consideration of the above-mentioned circumstances, at least one embodiment of the present disclosure aims to reduce water hammer that may occur in a heating medium flow path when starting the supply of heating medium for heating fuel to be supplied to a gas turbine combustor during startup of a gas turbine plant. [Means for solving the problem]

[0007] (1) A method for heating fuel according to at least one embodiment of the present disclosure includes: A fuel heating method for heating fuel to be supplied to a combustor of a gas turbine of a gas turbine plant, comprising the steps of: The gas turbine plant comprises: a fuel heater for heating the fuel to be supplied to the combustor; a cooler for cooling the heating medium after the fuel is heated by the fuel heater; a first flow path that connects the fuel heater and the cooler and through which the heating medium can flow after the fuel is heated by the fuel heater; A second flow path connected to the cooler and through which the heating medium can flow after being cooled by the cooler; a first on-off valve provided in the first flow path; a second on-off valve provided in the second flow path; Equipped with When the heating of the fuel by the fuel heater is started, opening the second on-off valve; After performing the step of opening the second on-off valve, a step of opening the first on-off valve; Execute.

[0008] (2) A fuel heating system according to at least one embodiment of the present disclosure, 1. A fuel heating system for heating fuel supplied to a combustor of a gas turbine, comprising: a fuel heater for heating the fuel to be supplied to the combustor; a cooler for cooling the heating medium after the fuel is heated by the fuel heater; a first flow path that connects the fuel heater and the cooler and through which the heating medium can flow after the fuel is heated by the fuel heater; A second flow path connected to the cooler and through which the heating medium can flow after being cooled by the cooler; a first on-off valve provided in the first flow path; a second on-off valve provided in the second flow path; a control device capable of controlling the first on-off valve and the second on-off valve so as to open the first on-off valve after opening the second on-off valve when starting heating of the fuel by the fuel heater; Equipped with. Effect of the Invention

[0009] According to at least one embodiment of the present disclosure, it is possible to reduce water hammer that may occur in a heating medium flow path when starting the supply of a heating medium for heating fuel to be supplied to a combustor of a gas turbine plant during startup. [Brief description of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram of a power generation plant according to an embodiment; [Diagram 2] 1 is a diagram for explaining an overall configuration of a fuel heating system according to an embodiment; [Diagram 3] FIG. 11 is a diagram for explaining the overall configuration of a fuel heating system according to another embodiment. [Figure 4] 3 is a flowchart showing a process flow when heating of fuel gas by a fuel heater is started in the heating system shown in FIG. 2. [Diagram 5] 4 is a flowchart showing a process flow when heating of fuel gas by a fuel heater is started in the heating system shown in FIG. 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such a configuration, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

[0012] With reference to FIG. 1, the configuration of a combined cycle power plant (hereinafter, referred to as a power plant) 1, which is a gas turbine plant according to one embodiment, will be described. As shown in FIG. 1, a power plant 1 mainly includes a gas turbine 2, a steam turbine 10, and a heat recovery steam generator 20.

[0013] The power plant 1 may be a single-shaft type in which the gas turbine 2 and the steam turbine 10 share a common rotating shaft, or may be a multi-shaft type in which the gas turbine 2 and the steam turbine 10 each have an independent rotating shaft. Note that Fig. 1 shows a single-shaft power plant 1.

[0014] A generator 8 is connected to the rotating shafts of the gas turbine 2 and the steam turbine 10. As a result, when the rotating shafts of the gas turbine 2 and the steam turbine 10 rotate, the generator 8 is driven to generate electric power.

[0015] The gas turbine 2 has an air compressor 3, a turbine 4, and a combustor 5. The air compressor 3 takes in and compresses the air, and supplies it to the combustor 5. The combustor 5 uses the compressed air supplied from the air compressor 3 as combustion air to combust fuel gas. The combustion gas generated by combustion in the combustor 5 is supplied to the turbine 4 to drive the turbine 4. The combustion gas (exhaust gas) after passing through the turbine 4 is guided to a heat recovery boiler 20, where it is used as a heat source for generating steam in the heat recovery boiler 20 and then exhausted.

[0016] In the power plant 1 according to this embodiment, a main exhaust line 40 is connected to an exhaust port of the turbine 4. A first exhaust line 41 and a second exhaust line 42 are connected to the main exhaust line 40. The downstream end of the first exhaust line 41 is connected to a chimney 43 . The downstream end of the second exhaust line 42 is connected to the heat recovery steam generator 20 . Further, the main exhaust line 40 is provided with an exhaust line switch 44 for switching the destination of the exhaust gas from the turbine 4 to the first exhaust line 41 or the second exhaust line 42.

[0017] The power plant 1 according to this embodiment can be operated by switching between combined cycle operation, in which the gas turbine 2 and the heat recovery steam generator 20 are operated, and single cycle operation, in which the gas turbine 2 is operated without operating the heat recovery steam generator 20. That is, when the power plant 1 according to this embodiment is operated in a single cycle, the exhaust line switch 44 switches the inflow destination of the exhaust gas from the turbine 4 to the first exhaust line 41. When the power plant 1 according to this embodiment is operated in combined cycle operation, the exhaust line switch 44 switches the destination of the exhaust gas from the turbine 4 to the heat recovery steam generator 20 via the second exhaust line 42.

[0018] In the heat recovery boiler 20, there are arranged a low-pressure economizer 27, a medium-pressure economizer 28, a high-pressure economizer 29, a low-pressure evaporator 24, a medium-pressure evaporator 25, and a high-pressure evaporator 26. The low-pressure evaporator 24 is attached to a low-pressure drum 21. The medium-pressure evaporator 25 is attached to a medium-pressure drum 22. The high-pressure evaporator 26 is attached to a high-pressure drum 23.

[0019] The steam turbine 10 includes a high-pressure turbine 11, an intermediate-pressure turbine 12, and a low-pressure turbine 13. High-pressure steam obtained by superheating saturated steam from a high-pressure drum 23 in a high-pressure superheater (not shown) in a heat recovery boiler 20 is supplied to the high-pressure turbine 11. The high-pressure steam supplied to the high-pressure turbine 11 performs work in the high-pressure turbine 11, and is then sent to a reheater (not shown) in the heat recovery boiler 20.

[0020] In addition to the high-pressure steam (low-temperature steam before reheating) that has done work in the high-pressure turbine 11, the reheater of the heat recovery boiler 20 is also supplied with steam obtained by superheating saturated steam from the intermediate-pressure drum 22 in an intermediate-pressure superheater (not shown) in the heat recovery boiler 20. The steam heated in the reheater is then supplied to the intermediate-pressure turbine 12 as reheated steam. The reheated steam supplied to the intermediate-pressure turbine 12 is supplied to the low-pressure turbine 13 after doing work in the intermediate-pressure turbine 12.

[0021] In addition to the reheated steam after having done work in the intermediate-pressure turbine 12, the low-pressure turbine 13 is also supplied with steam obtained by superheating saturated steam from the low-pressure drum 21 in a low-pressure superheater (not shown) in the heat recovery boiler 20.

[0022] The exhaust gas from the low-pressure turbine 13 is guided to the condenser 15 and condensed. The water generated in the condenser 15 is introduced into the low-pressure economizer 27 by the low-pressure feed water pump 16. The power generation plant 1 of this embodiment has a high-medium pressure feed water pump suction side feed water line 33 that connects the low-pressure economizer 27 and the high-medium pressure feed water pump 17, and a low-pressure drum feed water line 34 that branches off from the high-medium pressure feed water pump suction side feed water line 33 and is connected to the low-pressure drum 21. A portion of the water that has passed through the low-pressure economizer 27 is supplied to the low-pressure drum 21 via the high-medium pressure feedwater pump suction side feedwater line 33 and the low-pressure drum feedwater line 34, and the remainder is guided to the high-medium pressure feedwater pump 17 via the high-medium pressure feedwater pump suction side feedwater line 33. The high-medium pressure feedwater pump 17 supplies high-pressure feedwater to the high-pressure drum 23 via the high-pressure economizer 29, and supplies medium-pressure water to the medium-pressure drum 22 via the medium-pressure economizer 28. The water supplied to the high-pressure drum 23, the medium-pressure drum 22, and the low-pressure drum 21 is evaporated by heat exchange with the exhaust gas from the turbine 4 in the high-pressure evaporator 26, the low-pressure evaporator 24, and the medium-pressure evaporator 25, respectively, and is stored as saturated steam in each drum (23, 22, 21).

[0023] In the power plant 1 according to this embodiment, the condensate line 31 on the discharge side of the low-pressure feed water pump 16 branches into a low-pressure economizer feed water line 31a that supplies water to the low-pressure economizer 27, and a bypass line 31b that supplies water to the low-pressure drum 21, bypassing the low-pressure economizer 27. By opening a bypass valve 32 provided in the bypass line 31b, the water from the low-pressure feed water pump 16 is supplied to the low-pressure drum 21, bypassing the low-pressure economizer 27. In addition, in the power generation plant 1 of this embodiment, when the bypass valve 32 is opened and water from the low-pressure feed water pump 16 is supplied to the low-pressure drum 21, bypassing the low-pressure economizer 27, a portion of the drum water in the low-pressure drum 21 is guided to the high / medium pressure feed water pump 17 via the low-pressure drum feed water line 34 and the high / medium pressure feed water pump suction side feed water line 33. As a result, by opening the bypass valve 32, a portion of the drum water in the low-pressure drum 21 is supplied as a heating medium to a fuel heater 51 (described later) via the medium-pressure economizer 28, as described later. Furthermore, by closing the bypass valve 32, the water heated in the low pressure economizer 27 is supplied to the fuel heater 51 as a heating medium via the medium pressure economizer .

[0024] Furthermore, the power plant 1 according to this embodiment includes a fuel heating system 50 for heating the fuel (fuel gas) to be supplied to the combustor 5. The heating system 50 will be described below with reference to Figs. 2 and 3.

[0025] FIG. 2 is a diagram for explaining the overall configuration of a fuel heating system 50A according to one embodiment. FIG. 3 is a diagram for explaining the overall configuration of a fuel heating system 50B according to another embodiment. In the following description, when there is no particular distinction between the heating system 50A shown in Figure 2 and the heating system 50B shown in Figure 3, or when the heating system 50A shown in Figure 2 and the heating system 50B shown in Figure 3 are referred to collectively, they will be referred to simply as the heating system 50 without adding an alphabet at the end of the reference number.

[0026] Some embodiments of the heating system 50 include a fuel heater 51, a cooler 53, a fuel flow path 55, a heating medium flow path 57, and a cooling medium flow path 59. The heating system 50 of some embodiments includes a first on-off valve 71 provided in the first flow path 61, a second on-off valve 72 provided in the second flow path 62, and a supply valve 75 which is an on-off valve provided in the supply flow path 65.

[0027] The heating system 50B shown in FIG. 3 includes a bypass flow passage 67 that bypasses the first on-off valve, and a bypass on-off valve 77 provided in the bypass flow passage.

[0028] (Fuel heater 51) In the heating system 50 according to some embodiments, the fuel heater 51 is a heater for heating the fuel (fuel gas) to be supplied to the combustor 5. The fuel heater 51 is provided midway through a fuel flow passage 55 for supplying the fuel gas to the combustor 5. In the heating system 50 according to some embodiments, heated water from the medium pressure economizer 28 can be supplied to the fuel heater 51 as a heating medium for heating the fuel gas. That is, in the heating system 50 according to some embodiments, a supply flow passage 65 (described later) for supplying heated water from the medium pressure economizer 28 to the fuel heater 51 as a heating medium is connected to the fuel heater 51.

[0029] (Cooler 53) In the heating system 50 according to some embodiments, the cooler 53 is a cooler for cooling the heating medium after the fuel gas is heated by the fuel heater 51. In the heating system 50 according to some embodiments, the cooler 53 is connected to the fuel heater 51 via a first flow path 61 described later, and allows the heating medium from the fuel heater 51 to flow into the cooler 53. In the heating system 50 according to some embodiments, the cooler 53 can be supplied with water from the low-pressure feed water pump 16 as a cooling medium for cooling the heating medium.

[0030] (Fuel passage 55) In the heating system 50 according to some embodiments, the fuel flow passage 55 is a flow passage for supplying fuel gas, which is fuel to be combusted in the combustor 5, to the combustor 5. In the heating system 50 according to some embodiments, as described above, the fuel heater 51 is provided midway along the fuel flow passage 55. For ease of explanation, the fuel flow passage 55 upstream of the fuel heater 51 is also referred to as an upstream fuel flow passage 55U, and the fuel flow passage 55 downstream of the fuel heater 51 is also referred to as a downstream fuel flow passage 55D.

[0031] (heating medium flow path 57) In the heating system 50 according to some embodiments, the heating medium flow path 57 is a flow path through which heated water from the medium pressure economizer 28 can flow as a heating medium for heating the fuel gas. In the heating system 50 according to some embodiments, the heating medium flow path 57 includes a supply flow path 65, a first flow path 61, and a second flow path 62. In the heating system 50B shown in FIG. 3, the heating medium flow path 57 includes a bypass flow path 67 that bypasses a first on-off valve 71 described later.

[0032] (Supply Channel 65) In some embodiments of the heating system 50, the supply passage 65 is a passage for supplying heated water from the intermediate pressure economizer 28 to the fuel heater 51, and the fuel heater 51 is connected downstream of the supply passage 65.

[0033] In the heating system 50 according to some embodiments, the supply passage 65 is provided with a supply valve 75 which is an on-off valve that permits or prohibits the flow of the heating medium through the supply passage 65. In the heating system 50 according to some embodiments, the supply valve 75 is an air-driven valve that is driven by compressed air, which is, for example, the utility air of the power plant 1.

[0034] (First flow path 61) In the heating system 50 according to some embodiments, the first flow path 61 connects the fuel heater 51 and the cooler 53, and is a flow path through which the heating medium can flow after the fuel gas is heated by the fuel heater 51.

[0035] In the heating system 50 according to some embodiments, the first flow path 61 is provided with a first on-off valve 71 that is an on-off valve that permits or prohibits the flow of the heating medium in the first flow path 61. In the heating system 50 according to some embodiments, the first on-off valve 71 is an air-driven valve that is driven by compressed air that is, for example, utility air of the power plant 1. In the heating system 50B shown in FIG. 3, a speed controller 95 is provided in a compressed air flow path 97 that drives the first on-off valve 71 to adjust the flow rate of the compressed air that drives the first on-off valve 71 and thereby adjust the opening and closing speed of the first on-off valve 71.

[0036] (Second flow path 62) In the heating system 50 according to some embodiments, the second flow path 62 is a flow path through which the heating medium can flow after being cooled by the cooler 53, and the cooler 53 is connected to the upstream side of the second flow path 62. In the heating system 50 according to some embodiments, the downstream end of the second flow path 62 is connected to a downstream cooling medium flow path 59D described later.

[0037] In the heating system 50 according to some embodiments, the second passage 62 is provided with a second on-off valve 72 that is an on-off valve that allows or prohibits the flow of the heating medium through the second passage 62. In the heating system 50 according to some embodiments, the second on-off valve 72 is an air-driven valve that is driven by compressed air, which is, for example, the utility air of the power plant 1.

[0038] (Bypass flow path 67) In the heating system 50B shown in FIG. 3, the bypass flow path 67 is a flow path for bypassing the first on-off valve 71, and is connected to the flow path upstream and downstream of the first on-off valve in the first flow path 61. The bypass passage 67 is provided with a bypass on-off valve 77 which is an on-off valve that permits or prohibits the flow of the heating medium through the bypass passage 67. The bypass on-off valve 77 is an air-driven valve that is driven by compressed air which is, for example, the utility air of the power plant 1. The bypass flow passage 67 is configured so that the heating medium flows at a flow rate smaller than the flow rate of the heating medium flowing through the first on-off valve 71 when the first on-off valve 71 is fully open. Specifically, for example, the flow passage cross-sectional area of ​​the bypass flow passage 67 may be smaller than that of the first flow passage 61. In addition, the bypass flow passage 67 may be provided with a flow rate limiting member such as an orifice for limiting the flow rate of the heating medium flowing through the bypass flow passage 67. The flow rate of the heating medium in the bypass flow passage 67 is preferably set to a level at which water hammer does not occur even if the bypass on-off valve 77 is opened before the first on-off valve 71 is opened.

[0039] (coolant flow passage 59) In the heating system 50 according to some embodiments, the cooling medium flow path 59 is a flow path through which water from the low-pressure feed water pump 16 can flow as a cooling medium for cooling the heating medium in the cooler 53, and the cooler 53 is provided midway through the cooling medium flow path 59. For ease of explanation, the cooling medium flow path 59 upstream of the cooler 53 is also referred to as an upstream cooling medium flow path 59U, and the cooling medium flow path 59 downstream of the cooler 53 is also referred to as a downstream cooling medium flow path 59D. In the heating system 50 according to some embodiments, the upstream cooling medium passage 59U can supply water from the low-pressure feed water pump 16 to the cooler 53. In the heating system 50 according to some embodiments, the downstream cooling medium passage 59D can supply the cooling medium after the heating medium is cooled by the cooler 53 to the low-pressure economizer 27. As described above, the downstream end of the second passage 62 is connected to the downstream cooling medium passage 59D.

[0040] The heating system 50 according to some embodiments includes a control device 90 capable of controlling the opening and closing of each of the above-mentioned valves. The control device 90 may be, for example, a control device for controlling the entire gas turbine 2. The control device 90 includes a processor 91 that executes various arithmetic processes, and a memory 93 (not shown) that non-temporarily or temporarily stores various data processed by the processor 91. The processor 91 is realized by a CPU, a GPU, an MPU, a DSP, various other arithmetic devices, or a combination of these. The memory 93 is realized by a ROM, a RAM, a flash memory, or a combination of these.

[0041] In the heating system 50 according to some embodiments configured as described above, when the supply valve 75, the first on-off valve 71, and the second on-off valve 72 are open, the heated water from the intermediate pressure economizer 28 is supplied as a heating medium to the fuel heater 51. As a result, the fuel gas supplied from the upstream fuel passage 55U to the fuel heater 51 is heated by the fuel heater 51 and supplied to the combustor 5 via the downstream fuel passage 55D.

[0042] After the fuel gas is heated by the fuel heater 51 , the heating medium flows into the cooler 53 via the first flow path 61 , is cooled by the cooling medium in the cooler 53 , and flows into the second flow path 62 . The heating medium that has flowed into the second flow passage 62 merges with the cooling medium flowing through the downstream cooling medium flow passage 59D, and returns to the low pressure economizer 27 together with the cooling medium flowing through the downstream cooling medium flow passage 59D.

[0043] (Risk of water hammer occurring) During the shutdown period of the power plant 1, if the temperature of the heating medium drops with the first on-off valve 71 and the second on-off valve 72 closed, an air layer may be generated in the flow path between the first on-off valve 71 and the second on-off valve 72. Therefore, when the fuel heater 51 starts heating the fuel gas at the startup of the power plant 1, water hammer may occur in the heating medium flow path 57 when the flow of the heating medium is resumed. That is, if the first on-off valve 71 is opened before the second on-off valve 72 is opened in a state where an air layer exists in the flow path between the first on-off valve 71 and the second on-off valve 72 at the next startup of the power plant 1, and the flow of the heating medium into the cooler 53 is permitted, the pressure in the flow path upstream of the second on-off valve 72 may rise relatively rapidly, and water hammer may occur in the flow path upstream of the second on-off valve 72.

[0044] (Suppression of water hammer in heating system 50A) Therefore, in the heating system 50A shown in FIG. 2, when starting to heat the fuel gas by the fuel heater 51, the second on-off valve 72 is opened before opening the first on-off valve 71, and the first on-off valve 71 is opened after the second on-off valve 72 is opened. This reduces the possibility of water hammer occurring in the heating medium flow path 57 even when the first on-off valve 71 is opened. This reduces the water hammer that may occur in the heating medium flow path 57 when the supply of the heating medium starts.

[0045] Fig. 4 is a flowchart showing a process flow when starting heating of fuel gas by the fuel heater 51 in the heating system 50A shown in Fig. 2. A program for executing the process shown in the flowchart in Fig. 4 is read from the memory 93 and executed by the processor 91 of the control device 90 of the heating system 50A shown in Fig. 2. A fuel heating method according to one embodiment includes step S1 of opening the supply valve 75, step S3 of opening the second opening / closing valve 72, step S5 of waiting for a second specified time or longer, and step S7 of opening the first opening / closing valve 71. Before step S1 of opening the supply valve 75 is performed, the supply valve 75, the first opening / closing valve 71, and the second opening / closing valve 72 are closed.

[0046] (Step S1: Opening supply valve 75) Step S1 of opening the supply valve 75 is a step of opening the supply valve 75 in the heating system 50A shown in Fig. 2. In step S1 of opening the supply valve 75, the processor 91 outputs a control signal to a control valve (not shown) for compressed air so as to send compressed air for driving the supply valve 75 to an actuator (not shown) for driving the supply valve 75. As a result, compressed air is supplied to the actuator (not shown) to drive the supply valve 75 open, and the supply valve 75 opens.

[0047] (Step S3: Opening the second on-off valve 72) Step S3 of opening the second on-off valve 72 is a step of opening the second on-off valve 72 in the heating system 50A shown in Fig. 2. In step S3 of opening the second on-off valve 72, the processor 91 outputs a control signal to a control valve (not shown) for compressed air so as to send compressed air for driving the second on-off valve 72 to an actuator (not shown) for driving the second on-off valve 72. As a result, compressed air is supplied to the actuator (not shown) to drive the second on-off valve 72 to open, and the second on-off valve 72 opens.

[0048] (Step S5 of waiting for a second specified time or longer) Step S5 of waiting for the second specified time or more is a step of waiting for the second specified time t2 or more from the execution of step S3 of opening the second on-off valve 72 until the execution of step S7 of opening the first on-off valve 71. Here, in the heating system 50 of some embodiments, it is considered that the air layer that was present in the flow path between the first on-off valve 71 and the second on-off valve 72 will flow into the flow path downstream of the second on-off valve 72 (second flow path 62) when the second on-off valve 72 opens due to the shape or attitude of the flow path, etc. Therefore, in the heating system 50A shown in Figure 2, by waiting for a second specified time t2 or longer before performing step S7 of opening the first on-off valve 71, at least a portion of the air layer is caused to flow into the second flow path 62 downstream of the second on-off valve 72, thereby reducing the possibility of water hammer occurring in the flow path when step S7 of opening the first on-off valve 71 is later performed.

[0049] In addition, the second specified time t2 may be, for example, a time longer than the time required for air (the above-mentioned air layer) generated in the flow path between the first on-off valve 71 and the second on-off valve 72 to reach the flow path downstream of the second on-off valve 72 in the second flow path 62. This can further reduce the possibility of water hammer occurring in the heating medium flow path 57 when the first on-off valve 71 is opened.

[0050] (Step S7: Opening the first on-off valve 71) Step S7 of opening the first on-off valve 71 is a step of opening the first on-off valve 71 in the heating system 50A shown in Fig. 2 after performing step S3 of opening the second on-off valve 72 and further performing step S5 of waiting for a second specified time or more. In step S7 of opening the first on-off valve 71, the processor 91 outputs a control signal to a control valve for compressed air (not shown) so as to send compressed air for driving the first on-off valve 71 to an actuator (not shown) for driving the first on-off valve 71. As a result, compressed air is supplied to the actuator (not shown) to drive the first on-off valve 71 to open, and the first on-off valve 71 opens. This starts the flow of the heating medium through the heating medium flow path 57 of the heating system 50A shown in FIG.

[0051] In step S7 of opening the first on-off valve, the first on-off valve 71 may be opened so that the time required from when the first on-off valve 71 starts to open until when it finishes opening is equal to or longer than the first specified time t1. This reduces the rate at which pressure rises in the flow passage downstream of the first on-off valve 71 when the first on-off valve 71 is opened, thereby further reducing the possibility of water hammer occurring in the heating medium flow passage 57. 2, the speed controller 95 for adjusting the opening and closing speed of the first on-off valve 71 is provided, so that the speed at which the first on-off valve 71 opens can be made relatively slow. Therefore, by appropriately setting the speed controller 95, the time required for the first on-off valve 71 to open from the start to the end can be made to be equal to or longer than the first specified time t1.

[0052] The first specified time t1 may be a time that can sufficiently reduce the possibility of water hammer occurring in the flow path when the first on-off valve 71 is opened. The first specified time t1 may be, for example, 20 seconds or more.

[0053] The heating system 50A shown in FIG. 2 includes a fuel heater 51, a cooler 53, a first passage 61, a second passage 62, a first on-off valve 71, a second on-off valve 72, and a control device 90. 2, when starting heating of fuel gas by the fuel heater 51, the second on-off valve 72 is opened before the first on-off valve 71 is opened, so that it is possible to reduce the possibility of water hammer occurring in the heating medium flow path 57 even if the first on-off valve 71 is subsequently opened. This makes it possible to reduce water hammer that may occur in the heating medium flow path 57 when starting supply of the heating medium.

[0054] (Suppression of water hammer in heating system 50B) In the heating system 50B shown in FIG. 3, when starting to heat the fuel gas by the fuel heater 51, after opening the second on-off valve 72, the bypass on-off valve 77 is opened before opening the first on-off valve 71, and the first on-off valve 71 is opened after the bypass on-off valve 77 is opened. As a result, the rate of increase in pressure in the flow path downstream of the first on-off valve 71 when the bypass on-off valve 77 is opened before the first on-off valve 71 is opened is slower than when the first on-off valve 71 is opened before the bypass on-off valve 77 is opened. This reduces the possibility of water hammer occurring in the heating medium flow path 57. This reduces water hammer that may occur in the heating medium flow path 57 when the supply of the heating medium is started.

[0055] Fig. 5 is a flowchart showing a process flow when starting heating of fuel gas by the fuel heater 51 in the heating system 50B shown in Fig. 3. A program for executing the process shown in the flowchart in Fig. 5 is read from the memory 93 and executed by the processor 91 of the control device 90 of the heating system 50B shown in Fig. 3. A fuel heating method according to one embodiment includes step S11 of opening the supply valve 75, step S13 of opening the second opening / closing valve 72, step S15 of waiting for a second specified time or longer, step S17 of opening the bypass opening / closing valve 77, step S19 of waiting for a third specified time or longer, and step S21 of opening the first opening / closing valve 71. Before step S11 of opening the supply valve 75 is performed, the supply valve 75, the first on-off valve 71, the second on-off valve 72, and the bypass on-off valve 77 are closed.

[0056] (Step S11: Opening supply valve 75) Step S11 of opening the supply valve 75 is a step of opening the supply valve 75 in the heating system 50B shown in Fig. 3. In step S11 of opening the supply valve 75, the processor 91 outputs a control signal to a control valve (not shown) for compressed air so as to send compressed air for driving the supply valve 75 to an actuator (not shown) for driving the supply valve 75. As a result, compressed air is supplied to the actuator (not shown) to drive the supply valve 75 open, and the supply valve 75 opens.

[0057] (Step S13: Opening the second on-off valve 72) Step S13 of opening the second on-off valve 72 is a step of opening the second on-off valve 72 in the heating system 50B shown in Fig. 3. In step S13 of opening the second on-off valve 72, the processor 91 outputs a control signal to a control valve (not shown) for compressed air so as to send compressed air for driving the second on-off valve 72 to an actuator (not shown) for driving the second on-off valve 72. As a result, compressed air is supplied to the actuator (not shown) to drive the second on-off valve 72 to open, and the second on-off valve 72 opens.

[0058] (Step S15 of waiting for a second specified time or longer) Step S5 of waiting for the second specified time or more is a step of waiting for the second specified time t2 or more from the execution of step S13 of opening the second on-off valve 72 until the execution of step S17 of opening the bypass on-off valve 77. In the heating system 50B shown in FIG. 3, by waiting for the second specified time t2 or longer before performing step S17 of opening the bypass on-off valve 77, at least a portion of the air layer is caused to flow into the second flow path 62 downstream of the second on-off valve 72, thereby reducing the possibility of water hammer occurring in the flow path when step S17 of opening the bypass on-off valve 77 and step S21 of opening the first on-off valve 71 are subsequently performed.

[0059] (Step S17: Opening the bypass on-off valve 77) 3, step S17 of opening the bypass on-off valve 77 is a step of opening the bypass on-off valve 77 after step S13 of opening the second on-off valve 72 is performed and before step S21 of opening the first on-off valve 71 is performed. In step S17 of opening the bypass on-off valve 77, the processor 91 outputs a control signal to a control valve for compressed air (not shown) so as to send compressed air for driving the bypass on-off valve 77 to an actuator (not shown) for driving the bypass on-off valve 77. As a result, compressed air is supplied to the actuator (not shown) to drive the bypass on-off valve 77 open, and the bypass on-off valve 77 opens. When step S17 of opening the bypass on-off valve 77 is performed, the heating medium upstream of the first on-off valve 71 flows downstream of the first on-off valve 71 via the bypass flow path 67, and the pressure difference between the first flow path 61 upstream of the first on-off valve 71 and the first flow path 61 downstream of the first on-off valve 71 gradually decreases. When step S17 of opening the bypass on-off valve 77 is performed, the flow of the heating medium through the heating medium flow path 57 of the heating system 50B shown in FIG. 3 begins, although at a relatively small flow rate.

[0060] (Step S19: waiting for a third specified time or longer) Step S19 of waiting for the third specified time or more is a step of waiting for the third specified time or more t3 from the execution of step S17 of opening the bypass on-off valve 77 until the execution of step S21 of opening the first on-off valve 71. In addition, the third specified time t3 may be a time longer than the time required for the pressure difference between the first flow path 61 upstream of the first on-off valve 71 and the first flow path 61 downstream of the first on-off valve 71 to be reduced to a level where water hammer does not occur in the flow path even if the first on-off valve 71 is subsequently opened by performing step S17 of opening the bypass on-off valve 77. This can reduce the possibility of water hammer occurring in the heating medium flow path 57 when the first on-off valve 71 is opened.

[0061] (Step S21: Opening the first on-off valve 71) Step S21 of opening the first on-off valve 71 is a step of opening the first on-off valve 71 in the heating system 50B shown in Fig. 3 after performing step S19 of waiting for a third specified time or more. In step S21 of opening the first on-off valve 71, the processor 91 outputs a control signal to a control valve for compressed air (not shown) so as to send compressed air for driving the first on-off valve 71 to an actuator (not shown) for driving the first on-off valve 71. As a result, compressed air is supplied to the actuator (not shown) so as to drive the first on-off valve 71 to open, and the first on-off valve 71 opens.

[0062] The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications. For example, in the above-described embodiment, heated water from the medium pressure economizer 28 is used as the heating medium for heating the fuel gas, but water other than the heated water from the medium pressure economizer 28 may be used as long as it is water from various places in the heat recovery boiler 20 that can heat the fuel gas in the fuel heater 51.

[0063] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A fuel heating method according to at least one embodiment of the present disclosure is a fuel heating method for heating a fuel (fuel gas) to be supplied to a combustor 5 of a gas turbine 2 of a gas turbine plant (power plant 1). The gas turbine plant (power plant 1) includes a fuel heater 51 for heating the fuel (fuel gas) to be supplied to the combustor 5, a cooler 53 for cooling a heating medium after the fuel (fuel gas) is heated by the fuel heater 51, a first flow path 61 connecting the fuel heater 51 and the cooler 53 and through which the heating medium after the fuel is heated by the fuel heater 51 can flow, a second flow path 62 connected to the cooler 53 and through which the heating medium after being cooled by the cooler 53 can flow, a first on-off valve 71 provided in the first flow path 61, and a second on-off valve 72 provided in the second flow path 62. In the fuel heating method according to at least one embodiment of the present disclosure, when starting to heat the fuel (fuel gas) by the fuel heater 51, step S3 of opening the second on-off valve 72 is performed, and after step S3 of opening the second on-off valve 72, step S7 of opening the first on-off valve 71 is performed.

[0064] According to the above method (1), when starting heating of the fuel (fuel gas) by the fuel heater 51, the second on-off valve 72 is opened before opening the first on-off valve 71, so that it is possible to reduce the possibility of water hammer occurring in the flow path (heating medium flow path 57) even if the first on-off valve 71 is subsequently opened. This makes it possible to reduce water hammer that may occur in the heating medium flow path (heating medium flow path 57) when starting supply of the heating medium.

[0065] (2) In some embodiments, in the method of (1) above, in step S7 of opening the first on-off valve 71, the first on-off valve 71 is opened so that the time required from when the first on-off valve 71 starts to open to when it stops opening is equal to or longer than a first specified time t1.

[0066] According to the above method (2), the rate at which the pressure rises in the flow path downstream of the first on-off valve 71 when the first on-off valve 71 is opened can be reduced, thereby further reducing the possibility of water hammer occurring in the flow path (heating medium flow path 57).

[0067] (3) In some embodiments, in the method of (2) above, in step S7 of opening the first on-off valve 71, the first on-off valve 71 can be opened so that the required time is equal to or longer than the first specified time t1 by controlling the supply speed of the fluid (compressed air, which is the utility air of the power plant 1) that provides the driving force for opening and closing the first on-off valve 71 when it is supplied to the drive unit for opening and closing the first on-off valve 71.

[0068] According to the above method (3), the rate at which the pressure rises in the flow path downstream of the first on-off valve 71 when the first on-off valve 71 is opened can be reduced, thereby further reducing the possibility of water hammer occurring in the flow path (heating medium flow path 57).

[0069] (4) In some embodiments, any of the methods (1) to (3) above may include a step S5 of waiting for a second specified time t2 or more from the execution of step S3 of opening the second on-off valve 72 until the execution of step S7 of opening the first on-off valve 71.

[0070] It is possible that, due to the shape or posture of the flow path, the air layer that was present in the flow path between the first on-off valve 71 and the second on-off valve 72 will flow into the flow path downstream of the second on-off valve 72 (the second flow path 62 downstream of the second on-off valve 72) when the second on-off valve 72 opens. According to the method (4) above, by waiting for the second specified time t2 or more from the execution of step S3 of opening the second on-off valve 72 until the execution of step S7 of opening the first on-off valve 71, it is expected that at least a part of the air layer will flow into the flow path downstream of the second on-off valve 72 (the second flow path 62 downstream of the second on-off valve 72). This makes it possible to further reduce the possibility of water hammer occurring in the flow path (heating medium flow path 57) when the first on-off valve 71 is opened.

[0071] (5) In some embodiments, in the method of (4) above, the second specified time t2 may be longer than the time required for air generated in the flow path between the first on-off valve 71 and the second on-off valve 72 to reach the flow path downstream of the second on-off valve 72 in the second flow path 62.

[0072] According to the above method (5), it is possible to further reduce the possibility that water hammer will occur in the flow path (heating medium flow path 57) when the first on-off valve 71 is opened.

[0073] (6) In some embodiments, in any of the methods (1) to (5) above, the gas turbine plant (power plant 1) may include a supply passage 65 connected to the fuel heater 51 for supplying a heating medium to the fuel heater 51, and a supply valve 75 which is an on-off valve provided in the supply passage 65. When starting to heat the fuel (fuel gas) by the fuel heater 51, step S1 of opening the supply valve 75 may be performed before performing step S3 of opening the second on-off valve 72.

[0074] According to the above method (6), the supply valve 75 may be opened before carrying out step S3 of opening the second on-off valve 72.

[0075] (7) In some embodiments, in the method of (1) above, the gas turbine plant (power plant 1) is configured so that the heating medium flows at a flow rate less than the flow rate of the heating medium flowing through the first on-off valve 71 when the first on-off valve 71 is fully open, and includes a bypass flow passage 67 that bypasses the first on-off valve 71, and a bypass on-off valve 77 provided in the bypass flow passage 67. In some embodiments, when starting heating of the fuel (fuel gas) by the fuel heater 51, after performing step S3 of opening the second on-off valve 72, step S17 of opening the bypass on-off valve 77 is performed before performing step S7 of opening the first on-off valve 71. Step S21 of opening the first on-off valve 71 is performed after performing step S17 of opening the bypass on-off valve 77.

[0076] According to the method (7) above, the rate of increase in pressure in the flow path downstream of the first on-off valve 71 when the bypass on-off valve 77 is opened before the first on-off valve 71 is opened is slower than when the first on-off valve 71 is opened before the bypass on-off valve 77 is opened, thereby reducing the possibility of water hammer occurring in the flow path (heating medium flow path 57). This makes it possible to reduce water hammer that may occur in the heating medium flow path (heating medium flow path 57) when the supply of the heating medium is started.

[0077] (8) The fuel heating system 50A according to at least one embodiment of the present disclosure is a fuel heating system for heating the fuel (fuel gas) to be supplied to the combustor 5 of the gas turbine 2. A fuel heating system 50A according to at least one embodiment of the present disclosure includes a fuel heater 51 for heating a fuel (fuel gas) to be supplied to a combustor 5, a cooler 53 for cooling the heating medium after the fuel (fuel gas) is heated by the fuel heater 51, a first flow path 61 connecting the fuel heater 51 and the cooler 53 and through which the heating medium after the fuel is heated by the fuel heater 51 can flow, a second flow path 62 connected to the cooler 53 and through which the heating medium after being cooled by the cooler 53 can flow, a first opening / closing valve 71 provided in the first flow path 61, a second opening / closing valve 72 provided in the second flow path 62, and a control device 90 capable of controlling the first opening / closing valve 71 and the second opening / closing valve 72 to open the first opening / closing valve 71 after opening the second opening / closing valve 72 when heating of the fuel (fuel gas) by the fuel heater 51 is started.

[0078] According to the above configuration (8), when starting heating of the fuel (fuel gas) by the fuel heater 51, the second on-off valve 72 is opened before opening the first on-off valve 71, so that it is possible to reduce the possibility of water hammer occurring in the flow path (heating medium flow path 57) even if the first on-off valve 71 is subsequently opened. This makes it possible to reduce water hammer that may occur in the heating medium flow path (heating medium flow path 57) when starting supply of the heating medium. [Explanation of symbols]

[0079] 1. Gas turbine plants (power plants) 2. Gas turbine 4. Turbine 5. Combustor 10. Steam Turbine 16 Low pressure water supply pump 28 Medium pressure economizer 50, 50A, 50B Heating Systems 51 Fuel heater 53 Cooler 55 Fuel flow passage 57 Heating medium flow path 59 Coolant flow passage 61 First Channel 62 Second Stream 65 Supply Channel 67 Bypass flow path 71 First opening and closing valve 72 Second opening and closing valve 75 Supply valve 77 Bypass valve

Claims

1. A fuel heating method for heating fuel to be supplied to a combustor of a gas turbine of a gas turbine plant, comprising the steps of: The gas turbine plant comprises: a fuel heater for heating the fuel to be supplied to the combustor; a cooler for cooling the heating medium after the fuel is heated by the fuel heater; a first flow path that connects the fuel heater and the cooler and through which the heating medium can flow after the fuel is heated by the fuel heater; A second flow path connected to the cooler through which the heating medium can flow after being cooled by the cooler; a first on-off valve provided in the first flow path; a second on-off valve provided in the second flow path; Equipped with When the heating of the fuel by the fuel heater is started, opening the second on-off valve; a step of opening the first on-off valve after performing the step of opening the second on-off valve; Execute Fuel heating methods.

2. In the step of opening the first on-off valve, the first on-off valve is opened so that a required time from when the first on-off valve starts to open until when the first on-off valve finishes opening is equal to or longer than a first specified time.

2. The method of claim 1 .

3. In the step of opening the first on-off valve, a supply speed of a fluid that provides a driving force for opening and closing the first on-off valve is controlled when the fluid is supplied to a drive unit for opening and closing the first on-off valve, thereby opening the first on-off valve so that the required time is equal to or longer than the first specified time.

3. The method of claim 2.

4. a step of waiting for a second specified time or more from the execution of the step of opening the second on-off valve to the execution of the step of opening the first on-off valve; Equipped with A method for heating fuel according to any one of claims 1 to 3.

5. the second specified time is longer than a time required for air generated in a flow path between the first on-off valve and the second on-off valve to reach a flow path downstream of the second on-off valve in the second flow path.

5. The method of claim 4.

6. The gas turbine plant comprises: a supply passage connected to the fuel heater for supplying the heating medium to the fuel heater; a supply valve which is an on-off valve provided in the supply flow path; Equipped with When starting heating of the fuel by the fuel heater, a step of opening the supply valve is performed before the step of opening the second on-off valve is performed. A method for heating fuel according to any one of claims 1 to 3.

7. The gas turbine plant comprises: a bypass flow path that bypasses the first on-off valve, the bypass flow path being configured so that the heating medium flows at a flow rate that is smaller than the flow rate of the heating medium flowing through the first on-off valve when the first on-off valve is fully opened; a bypass on-off valve provided in the bypass flow path; Equipped with When the heating of the fuel by the fuel heater is started, After performing the step of opening the second on-off valve, a step of opening the bypass on-off valve is performed before performing the step of opening the first on-off valve; The step of opening the first on-off valve is performed after the step of opening the bypass on-off valve is performed.

2. The method of claim 1 .

8. 1. A fuel heating system for heating fuel supplied to a combustor of a gas turbine, comprising: a fuel heater for heating the fuel to be supplied to the combustor; a cooler for cooling the heating medium after the fuel is heated by the fuel heater; a first flow path that connects the fuel heater and the cooler and through which the heating medium can flow after the fuel is heated by the fuel heater; A second flow path connected to the cooler through which the heating medium can flow after being cooled by the cooler; a first on-off valve provided in the first flow path; a second on-off valve provided in the second flow path; a control device capable of controlling the first on-off valve and the second on-off valve so as to open the first on-off valve after opening the second on-off valve when heating of the fuel by the fuel heater is started; and Equipped with Fuel heating system.

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