Gas turbine and gas turbine control method

Abstract

This gas turbine can be driven by a combustion gas generated by mixing and burning compressed air generated by a compressor with fuel, and has a bleed line for guiding bleed air extracted from the compressor to an exhaust duct. The bleed line is provided with a bleed valve that can be switched from an open state to a closed state by the supply of control air. If the control air cannot be supplied, the bleed valve can be switched to the closed state by supplying emergency air from an emergency air supply system instead of the control air.

Description

Gas turbine and gas turbine control method

[0001] This application claims priority to Japanese Patent Application No. 2023-207345, filed with the Japan Patent Office on December 8, 2023, the contents of which are incorporated herein by reference.

[0002] Gas turbines are known that generate output by generating combustion gases by mixing and burning fuel and compressed air (combustion air) generated by a compressor in a combustor, and driving a turbine. Some gas turbines of this type are equipped with a bleed system for bleeding air from the compressor to prevent surging during start-up and shutdown. The bleed system has a bleed line configured to bypass bleed air from the compressor to an exhaust duct of the turbine, and a bleed valve is provided on the bleed line to adjust the flow rate of the bleed air (see, for example, Patent Document 1). The bleed valve can be opened and closed by control air. It is operated to an open state during start-up and shutdown of the gas turbine to prevent surging, and is operated to a closed state during normal operation (when the gas turbine is operating at a constant speed).

[0003] JP 2012-102648 A

[0004] Since each component of the gas turbine can operate using power from a commercial power source, for example, the gas turbine must be stopped in the event of a power outage (blackout). In order to prevent surging even when the gas turbine is stopped due to such a power outage, it is effective to design the bleed valve so that it is in an open state when control air is not supplied (i.e., so that the fail action is in the open direction).

[0005] After a gas turbine is shut down, there is a risk of a cat-back event occurring due to differences in metal temperature between components that make up the casing. Therefore, it is necessary to cool the casing by supplying cooling air using a fan or the like. If a bleed valve designed for a fail operation to open remains open because control air cannot be supplied, the cooling air from the fan is directed toward the exhaust duct, which may prevent sufficient cooling air from the fan from being obtained, making it impossible to cool the casing. As a result, if a cat-back event occurs in the gas turbine after shutdown, there is a risk that blades in the turbine or compressor may come into contact with the casing.

[0006] At least one embodiment of the present disclosure has been made in consideration of the above circumstances, and has an object to provide a gas turbine and a gas turbine control method that are capable of preventing the occurrence of a cat-back event by closing the bleed valve that has been opened to prevent surging in a gas turbine after it has stopped, even when control air required for opening and closing the bleed valve cannot be supplied.

[0007] In order to solve the above-mentioned problems, a gas turbine according to at least one embodiment of the present disclosure includes: a compressor for generating compressed air; a combustor for mixing and burning the compressed air with fuel to generate combustion gas; a turbine that can be driven by the combustion gas; an exhaust duct for discharging exhaust gas from the turbine; at least one bleed air line for guiding bleed air extracted from the compressor to the exhaust duct; at least one bleed valve that is provided in the at least one bleed air line and can be switched from an open state to a closed state by supply of control air; a control air supply system for supplying the control air; and an emergency air supply system for supplying emergency air to the at least one bleed air valve in place of the control air when the control air system is unable to supply the control air.

[0008] and an emergency air supply system for supplying emergency air to the at least one bleed valve in place of the control air, the gas turbine control method comprising: a compressor for generating compressed air; a combustor for mixing and burning the compressed air with fuel to generate combustion gas; a turbine that can be driven by the combustion gas; an exhaust duct for discharging exhaust gas from the turbine; at least one bleed line for guiding bleed air extracted from the compressor to the exhaust duct; at least one bleed valve that is provided in the at least one bleed line and is switchable from an open state to a closed state by a supply of control air; a control air supply system for supplying the control air; and an emergency air supply system for supplying emergency air to the at least one bleed valve in place of the control air, the gas turbine control method comprising: determining whether the control air can be supplied by the control air system; and, when it is determined that the control air cannot be supplied by the control air system, supplying the emergency air to the bleed valve in place of the control air.

[0009] According to at least one embodiment of the present disclosure, it is possible to provide a gas turbine and a gas turbine control method that are capable of preventing the occurrence of a cat-back event by closing the bleed valve that has been opened to prevent surging in the gas turbine after it has been stopped, even when control air required for opening and closing the bleed valve cannot be supplied.

[0010] 1 is a schematic configuration diagram of a gas turbine according to one embodiment. It is a block configuration diagram of the control device of FIG. 1. It is a time chart showing an opening / closing command, a supply state of control air to each bleed valve, and an opening / closing state of each bleed valve, together with the output and rotation speed of the gas turbine of FIG. 1 when a control air supply system is operable normally. It is a schematic configuration diagram showing an operating state of the gas turbine when each bleed valve of the gas turbine 1 is in an open state when the control air supply system is operable normally. It is a time chart showing an opening / closing command, a supply state of emergency air to each bleed valve, and an opening / closing state of each bleed valve, together with the output and rotation speed of the gas turbine of FIG. 1 when the control air supply system is inoperable. It is a schematic configuration diagram showing an operating state of the gas turbine when each bleed valve of the gas turbine is in an open state ... a closed state when the control air supply system is inoperable. It is a schematic configuration diagram of a gas turbine according to another embodiment. It is a block configuration diagram of the control device of FIG.

[0011] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the configurations described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0012] FIG. 1 is a schematic configuration diagram of a gas turbine 1 according to one embodiment. The gas turbine 1 includes a compressor 2, a combustor 4, a turbine 6, and an exhaust duct 8. The compressor 2 generates compressed air Ac by compressing combustion air A (e.g., outside air). Fuel F is supplied to the combustor 4 from a fuel supply system 10, and the fuel F is mixed with the compressed air Ac from the compressor 2 and combusted to generate combustion gas Gc. The combustion gas Gc drives the turbine 6, and after completing its work, the combustion gas is discharged to the outside from the exhaust duct 8 as exhaust gas Gex.

[0013] The fuel supply system 10 has a fuel supply line 12 connected to a fuel supply source (not shown). The fuel supply line 12 may be provided with a flow rate control valve for adjusting the flow rate of the fuel F and a shutoff valve for shutting off the fuel F.

[0014] The gas turbine 1 includes at least one bleed air line for guiding bleed air extracted from the compressor 2 to the exhaust duct 8, and further includes a fan 40 for stirring the air in the casing. In this embodiment, the bleed air lines include a high-pressure bleed air line 14H for bleeding high-pressure bleed air GaH from a relatively downstream side of the compressor 2, an intermediate-pressure bleed air line 14M for bleeding intermediate-pressure bleed air GaM, whose pressure is lower than the high-pressure bleed air GaH, from a side upstream of the high-pressure bleed air line 14H of the compressor 2, and a low-pressure bleed air line 14L for bleeding low-pressure bleed air GaL, whose pressure is lower than the intermediate-pressure bleed air GaM, from a side upstream of the intermediate-pressure bleed air line 14M of the compressor 2.

[0015] These bleed air lines are provided with bleed valves for adjusting the flow rate of each bleed air. Specifically, the high-pressure bleed air line 14H is provided with a high-pressure bleed air valve VH for adjusting the flow rate of high-pressure bleed air GaH. The medium-pressure bleed air line 14M is provided with a medium-pressure bleed air valve VM for adjusting the flow rate of medium-pressure bleed air GaM. The low-pressure bleed air line 14L is provided with a low-pressure bleed air valve VL for adjusting the flow rate of low-pressure bleed air GaL. The flow rate of each bleed air by these bleed air valves may be adjusted by opening and closing the bleed valves, or by adjusting the opening degree of the bleed valves.

[0016] Each bleed valve can be opened and closed by control air Act from a control air supply system 16. The control air supply system 16 includes a control air compressor 18 for compressing, for example, outside air to generate control air Act, and a control air supply line 20 for supplying the control air Act generated by the control air compressor 18. The control air supply line 20 is provided with a control air tank 19 capable of storing the control air Act generated by the control air compressor 18, and a dryer 21 for removing excess moisture from the control air Act.

[0017] The control air supply line 20 branches into first branch lines 22H1, 22M1, 22L1 for supplying control air Act to each bleed valve for closing the respective bleed valve, and second branch lines 22H2, 22M2, 22L2 for supplying control air Act to each bleed valve for opening the respective bleed valve. Specifically, the first branch line 22H1 is provided with a three-way valve V1H and a solenoid valve S1H, and by controlling the open / close states of these, control air Act can be supplied for closing the high-pressure bleed valve VH. The second branch line 22H2 is provided with a check valve VgH, a volume tank 24H, and a solenoid valve S2H, and by controlling the open / close state of the solenoid valve S2H, control air Act can be supplied for opening the high-pressure bleed valve VH.

[0018] The first branch line 22M1 is provided with a three-way valve V1M and a solenoid valve S1M, and by controlling the open / close states of these, control air Act can be supplied for closing the medium-pressure bleed valve VM. The second branch line 22M2 is provided with a check valve VgM, a volume tank 24M, and a solenoid valve S2M, and by controlling the open / close state of the solenoid valve S2M, control air Act can be supplied for opening the medium-pressure bleed valve VM.

[0019] The first branch line 22L1 is provided with a three-way valve V1L and a solenoid valve S1L, and by controlling the open / close states of these, control air Act can be supplied for closing the low-pressure bleed valve VL. The second branch line 22L2 is provided with a check valve VgL, a volume tank 24L, and a solenoid valve S2L, and by controlling the open / close state of the solenoid valve S2L, control air Act can be supplied for opening the low-pressure bleed valve VL.

[0020] The second branch lines 22H2, 22M2, 22L2 are provided with volume tanks 24H, 24M, 24L capable of storing control air Act. As a result, even if the control air supply system 16 is inoperable, the solenoid valves S2H, S2M, S2L can be opened to open the respective bleed valves using the control air Act stored in the volume tanks 24H, 24M, 24L, as will be described later with reference to Fig. 6. With this configuration, even if the control air supply system 16 is inoperable, the bleed valves can be opened to prevent surging in the gas turbine 1 during shutdown (i.e., a fail-open configuration).

[0021] The gas turbine 1 also includes an emergency air supply system 30 for supplying emergency air Aem instead of the control air Act from the above-described control air supply system 16. The emergency air supply system 30 includes an emergency air supply source 32 capable of supplying emergency air Aem, an emergency air line 34 for supplying the emergency air Aem from the emergency air supply source 32, and a solenoid valve S3 provided in the emergency air line 34. The emergency air supply source 32 is, for example, a cylinder device that stores the emergency air Aem at a predetermined pressure.

[0022] The emergency air line 34 is connected to three-way valves V1H, V1M, and V1L provided in the first branch line 22H1, 22M1, and 22L1, which is part of the supply line for control air Act, and is configured so that by opening the solenoid valves S4H, S4M, and S4L, emergency air Aem can be supplied to the first branch line 22H1, 22M1, and 22L1 via the three-way valves V1H, V1M, and V1L instead of the control air Act supplied from the control air supply system 16 for closing operation.

[0023] In this way, each solenoid valve operated when emergency air Aem is supplied can be opened and closed by a power source (for example, a battery) independent of the control air supply system 16, which is operated by a system power supply, for example. As a result, even if the control supply system 16 becomes inoperable due to a power outage (blackout) or the like, emergency air Aem can be supplied to each bleed valve and the bleed valve can be closed by operating each solenoid valve using an independent power source.

[0024] 1, in the turbine 6, each bleed line is connected to the lower side of the casing, and therefore, when the bleed valve is open, relatively cold air flows through each bleed line into the lower part of the casing. This increases the temperature difference between the lower part of the casing, where cooling is accelerated by the cold air, and the upper part of the casing, which becomes hot due to natural convection and is difficult to cool, and this increases cat-back deformation (oval deformation) of the lower part of the casing, which may reduce the clearance in the lower part of the casing.

[0025] In this embodiment, when a power outage (blackout) or the like does not occur, the fan 40 operates using a system power supply similar to the control air supply system 16, thereby agitating the air in the cabin of the turbine 6, thereby suppressing cabin deformation caused by the temperature difference between the upper and lower parts of the cabin. On the other hand, when a power outage (blackout) or the like occurs, if the fan 40 is inoperable, cat-back deformation may occur in the lower part of the cabin for the reasons described above. Therefore, in this embodiment, when a power outage (blackout) or the like occurs, the fan 40 can also be operated using a power supply independent of the system power supply (for example, an emergency power supply such as a battery), thereby agitating the air in the cabin and suppressing cat-back deformation.

[0026] The control device 100 is a control unit for controlling each component of the gas turbine 1 having the above-described configuration. The control device 100 is a control unit for controlling the gas turbine 1 and is configured, for example, with a central processing unit (CPU), a random access memory (RAM), a read-only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example. The CPU reads the program into the RAM or the like and executes information processing and arithmetic processing, thereby realizing various functions. The program may be pre-installed in a ROM or other storage medium, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Examples of computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0027] Fig. 2 is a block diagram of the control device 100 of Fig. 1. The control device 100 includes a bleed valve opening / closing command acquisition unit 102, a control air control unit 104, a supply state determination unit 106, and an emergency air control unit 108.

[0028] The bleed valve open / close command acquisition unit 102 is configured to acquire an open / close command C for each bleed valve. The open / close command C is acquired from the outside (for example, a higher-level control device) as a command signal for controlling the open / close state of each bleed valve.

[0029] The control air control unit 104 is configured to control the supply state of control air Act by the control air supply system 16 based on the opening / closing command C acquired by the bleed valve opening / closing command acquisition unit 102. The control air control unit 104 controls the opening and closing of each bleed valve by supplying control air Act to each bleed valve for an opening operation or a closing operation, together with the control air supply system 16, and by controlling each valve provided in each line leading to each bleed valve.

[0030] The supply state determination unit 106 is configured to determine the supply state of control air Act. The supply state of control air Act is determined by comparing the opening / closing command C acquired by the bleed valve opening / closing command acquisition unit 102 with the opening / closing state of each bleed valve (for example, the switching state of a limit switch (not shown) installed on each bleed valve). For example, if the ideal opening / closing state of each bleed valve identified from the opening / closing command C differs from the actual opening / closing state of each bleed valve detected based on the limit switch, it can be determined that the supply of control air Act for controlling the opening and closing of each bleed valve is impossible.

[0031] The emergency air control unit 108 is configured to control the supply state of emergency air Aem by the emergency air supply system 30 based on the determination result of the supply state determination unit 106. Specifically, when the supply state determination unit 106 determines that the supply of control air Act is impossible, the emergency air control unit 108 controls the supply state of emergency air Aem based on the opening / closing command C acquired by the bleed valve opening / closing command acquisition unit 102, instead of the control air Act. The emergency air control unit 108 controls the opening and closing of each bleed valve using emergency air Aem by controlling the emergency air supply system 30 as well as each valve provided in each line leading to each bleed valve.

[0032] Next, a specific explanation will be given of the shutdown operation of the gas turbine 1 having the above configuration. First, with reference to Figures 3 and 4, an explanation will be given of the shutdown operation of the gas turbine 1 when the control air supply system 16 can operate normally. Figure 3 is a time chart showing the output L and rotation speed R of the gas turbine 1 of Figure 1 when the control air supply system 16 can operate normally, as well as the opening / closing command C, the supply state of control air Act to each bleed valve, and the open / closed state of each bleed valve, and Figure 4 is a schematic diagram showing the operating state of the gas turbine 1 when each bleed valve of the gas turbine 1 is in an open state when the control air supply system 16 can operate normally.

[0033] 3, the gas turbine 1 is initially in a normal operating state in which the output L and the rotational speed R are substantially constant (for example, the rated output and the rated rotational speed). At this time, in the gas turbine 1, each bleed valve is in a closed state, as shown in FIG.

[0034] The gas turbine 1 starts a shutdown operation at time t1. After the gas turbine 1 starts the shutdown operation, the rotation speed R gradually decreases after the output L has sufficiently decreased. When the rotation speed R becomes equal to or less than a reference value at time t2, the opening / closing command C for the bleed valve is switched from the closed state to the open state. Here, if the control air supply system 16 can operate normally (if a power outage (blackout) or the like has not occurred), as shown in FIG. 4 , control air Act for switching each bleed valve to an open state is supplied from the control air supply system 16. Specifically, by switching the solenoid valves S1H, S1M, and S1L to a closed state, the flow paths for switching each bleed valve to a closed state are blocked, and by switching the solenoid valves S2H, S2M, and S2L to an open state, control air Act is supplied to each bleed valve via the flow paths for switching each bleed valve to an open state. As a result, each bleed valve is switched from a closed state to an open state, thereby preventing surging when the gas turbine 1 is shut down.

[0035] Then, when the first period T1 has elapsed from time t2, the opening / closing command C is switched again from the open state to the closed state in order to prevent the occurrence of a cat-back event in the gas turbine 1 after it has been shut down.

[0036] In Fig. 4, control air Act is normally supplied to each bleed valve from the control air supply system 16 based on the opening / closing command C, and each bleed valve is switched from the open state to the closed state so as to correspond to the opening / closing state C. This prevents the compressed air generated by the compressor 2 from flowing out to the bleed lines 14H, 14M, 14L, and ensures the cooling performance of the gas turbine 1 after shutdown, thereby making it possible to appropriately prevent a cat-back event.

[0037] Next, the shutdown operation of the gas turbine 1 when the control air supply system 16 is inoperable will be described with reference to Figures 5 to 7. Figure 5 is a time chart showing the output L and rotation speed R of the gas turbine 1 in Figure 1 when the control air supply system 16 is inoperable, as well as the opening / closing command C, the supply state of emergency air Aem to each bleed valve, and the open / closed state of each bleed valve, Figure 6 is a schematic configuration diagram showing the operating state of the gas turbine 1 when each bleed valve of the gas turbine 1 is in an open state when the control air supply system 16 is inoperable, and Figure 7 is a schematic configuration diagram showing the operating state of the gas turbine 1 when each bleed valve of the gas turbine 1 is in a closed state when the control air supply system 16 is inoperable.

[0038] In Fig. 5, the initial state of the gas turbine 1 is a normal operating state in which the output L and the rotational speed R are substantially constant (for example, the rated output and the rated rotational speed), as in the case of Fig. 3. At this time, in the gas turbine 1, each bleed valve is in a closed state, as shown in Fig. 1.

[0039] The gas turbine 1 starts a shutdown operation at time t1. After the gas turbine 1 starts the shutdown operation, its rotation speed R gradually decreases after its output power L has sufficiently decreased. When the rotation speed R falls below a reference value at time t2, the open / close command C for the bleed valve is switched from a closed state to an open state. If the control air supply system 16 is inoperable (due to a power outage (blackout), for example), control air Act for switching cannot be supplied to each bleed valve. In this case, as shown in FIG. 6 , solenoid valves S2H, S2M, and S2L, which can be operated by a power source (e.g., a battery) independent of the control air supply system 16, are opened to supply control air Act previously stored in volume tanks 24H, 24M, and 24L to each bleed valve, thereby opening each bleed valve. Thus, even if the control air supply system 16 is inoperable, surging can be prevented when the gas turbine 1 is shut down by switching each bleed valve to an open state.

[0040] Then, when the first period T1 has elapsed since time t2, the opening / closing command C is switched again from the open state to the closed state in order to prevent the occurrence of a cat-back event in the gas turbine 1 after it has been shut down. In this embodiment, since the gas turbine 1 has a plurality of bleed valves (the low-pressure bleed valve VL, the medium-pressure bleed valve VM, and the high-pressure bleed valve VH), the opening / closing command C is set so that these bleed valves are switched from the open state to the closed state in sequence at predetermined intervals. Specifically, at time t3-1, the opening / closing command C corresponding to the low-pressure bleed valve VL is switched from the open state to the closed state, at time t3-2, the opening / closing command C corresponding to the medium-pressure bleed valve VM is switched from the open state to the closed state, and at time t3-3, the opening / closing command C corresponding to the high-pressure bleed valve VH is switched from the open state to the closed state.

[0041] 5 , even if the opening / closing command C switches from the open state to the closed state as described above, the control air supply system 16 is inoperable, and therefore the control air Act cannot be used to close the bleed valves. In this manner, the supply state determination unit 106 determines that the control air supply system 16 is inoperable by comparing the opening / closing command C with the open / closed states of the bleed valves when the second period T2 (>first period T1) has elapsed since time t2. In this embodiment, when the second period T2 has elapsed since time t2, the opening / closing command C is in the closed state, but the bleed valves remain in the open state, and therefore it is determined that the control air supply system 16 is inoperable.

[0042] In this case, as shown in Fig. 7, the bleed valves are closed using emergency air Aem supplied by the emergency air supply system 30. At this time, the emergency air Aem can be supplied to each bleed valve by opening and closing solenoid valves that can be operated by a power source (for example, a battery) independent of the control air supply system 16. Specifically, by opening the solenoid valves S3 and S4H, S4M, S4L, flow paths are switched by the three-way valves V1H, V1M, V1L so that the emergency air Aem from the emergency air supply source 32 is introduced into each bleed valve via the emergency air supply line 34. As a result, from time t4-1 to t4-3, each bleed valve is switched to the closed state in sequence.

[0043] In this way, even when the control air supply system 16 is inoperable, each bleed valve can be closed by emergency air Aem from the emergency air supply system 30. This prevents compressed air generated by the compressor 2 from flowing into the bleed lines 14H, 14M, and 14L in the gas turbine 1 after shutdown, and ensures the cooling performance of the gas turbine 1 after shutdown, thereby making it possible to appropriately prevent a cat-back event.

[0044] Even if the control air supply system 16 is inoperable, the fan 40 can be operated by a power source (for example, an emergency power source such as a battery) independent of the system power source for operating the control air supply system 16. This allows the air in the turbine 6 cabin to be agitated and cat-back deformation at the bottom of the cabin to be effectively suppressed. Furthermore, in the event of a power outage (blackout), the opening and closing of the control valve related to the air supply to the cabin can also be performed by emergency air Aem supplied from the emergency air supply system 30.

[0045] 8 is a schematic configuration diagram of a gas turbine 1 according to another embodiment. In the following embodiment, unless otherwise specified, the gas turbine 1 has a configuration common to the above-described gas turbine 1 and further includes the following configuration.

[0046] 8 , the gas turbine 1 includes a rotor 60 that can rotate about a central axis O, and a casing 70 that is a stationary member provided around the rotor 60. The rotor 60 may be a compressor rotor included in the compressor 2 described above, a turbine rotor included in the turbine 6, or a member in which a compressor rotor and a turbine rotor are connected to each other. The casing 70 may be a compressor casing included in the compressor 2, a turbine casing included in the turbine 6, or an intermediate casing provided between the compressor casing and the turbine casing.

[0047] The passenger compartment 70 includes an upper passenger compartment portion 70a located above the central axis O and a lower passenger compartment portion 70b located below the central axis O. Although Fig. 8 illustrates the passenger compartment 70 in which the upper passenger compartment portion 70a and the lower passenger compartment portion 70b are integrally formed, the passenger compartment 70 may be formed by combining the upper passenger compartment portion 70a and the lower passenger compartment portion 70b, which are separate members, with each other.

[0048] A pair of temperature sensors 50a, 50b are provided at positions corresponding to different heights in the passenger compartment 70. In the example of Fig. 8, one temperature sensor 50a is provided in the upper passenger compartment 70a, and the other temperature sensor 50b is provided in the lower passenger compartment 70b. The upper passenger compartment temperature Ta detected by the temperature sensor 50a and the lower passenger compartment temperature Tb detected by the temperature sensor 50b are each sent to the control device 100 and can be used for calculation processing in the control device 100.

[0049] As described above, the casing 70 is provided with the fan 40 for stirring the air inside when the gas turbine 1 is stopped. When the gas turbine 1 is stopped, the air inside the casing 70 is stirred by the operation of the fan 40. This reduces the temperature difference ΔT that occurs between the casing upper part 70a and the casing lower part 70b in the stopped gas turbine 1, thereby suppressing the cat-back event.

[0050] As described above, the fan 40 can be operated by the power supply 42, which is an emergency power supply such as a battery, independent of the system power supply for operating the control air supply system 16. Therefore, even if a power outage (blackout) or the like occurs when the gas turbine 1 is stopped, the fan 40 can be operated by the power supply 42. However, if the power supply 42 also becomes unusable due to some factor during a power outage (blackout), the fan 40 may become inoperable. Therefore, in this embodiment, when the fan 40 is inoperable because the power supply 42 is unusable, a fan operation signal Sf indicating this is input to the control device 100.

[0051] Fig. 9 is a block diagram of the control device 100 of Fig. 8. Although components common to the above-described embodiment (see Fig. 2) are not shown in Fig. 9, the control device further includes a turning operation control unit 110, a temperature difference acquisition unit 112, a first abnormality determination unit 114, a first alarm output unit 116, a fan operation signal acquisition unit 118, a second abnormality determination unit 120, and a second alarm output unit 122.

[0052] The turning operation control unit 110 is configured to control a turning operation that rotates and drives the rotor 60 at a predetermined rotation speed when the gas turbine 1 is stopped. The turning operation is triggered by receiving a stop signal Ss for the gas turbine 1 (for example, a command signal transmitted when a stop switch of the gas turbine 1 is turned on), and is performed while the gas turbine 1 is stopped. In the turning operation, the rotor 60 is rotated and driven at a predetermined rotation speed within the casing 70, thereby preventing the rotor 60 from deforming due to its own weight while the gas turbine 1 is stopped.

[0053] The temperature difference acquisition unit 112 is configured to acquire the temperature difference ΔT between the upper compartment 70 a and the lower compartment 70 b. In this embodiment, the upper compartment temperature Ta detected by the temperature sensor 50 a provided in the upper compartment 70 a and the lower compartment temperature Tb detected by the temperature sensor 50 b provided in the lower compartment 70 b are input to the temperature difference acquisition unit 112, and the temperature difference ΔT is acquired as the difference between the two temperatures.

[0054] The first abnormality determination unit 114 is configured to perform an abnormality determination based on the temperature difference ΔT acquired by the temperature difference acquisition unit 112. Specifically, when the temperature difference ΔT is equal to or greater than a preset reference value, the first abnormality determination unit 114 determines that a cat-back event may occur due to a difference in the amount of thermal expansion between the upper compartment 70a and the lower compartment 70b, and performs an abnormality determination.

[0055] The first alarm output unit 116 is configured to output a first alarm W1 when an abnormality is determined by the first abnormality determination unit 114. If a cat-back event occurs, there is a risk that the rotor 60 may interfere with the surrounding casing 70 when a turning operation is performed in the stopped gas turbine 1. Therefore, when an abnormality is determined by the first abnormality determination unit 114, the first alarm W1 for prohibiting the turning operation is output, thereby urging the prohibition of the turning operation.

[0056] For example, the first alarm W1 may be a display signal for displaying a message on a display device 150 (see FIG. 8 ) such as a display, urging the operator to prohibit a turning operation. In this case, the display device 150 displays a message indicating that the turning operation should be prohibited based on the first alarm W1. Then, when an operator recognizes the display on the display device 150 and a turning operation is being performed on the stopped gas turbine 1, the operator can take appropriate action, such as stopping the turning operation.

[0057] The first alarm W1 may also be a control signal transmitted to the turning operation control unit 110 to prohibit the turning operation. In this case, the turning operation control unit 110 can automatically stop the turning operation being performed by the gas turbine 1 that is stopped by receiving the control signal (first alarm W1).

[0058] The fan operation signal acquisition unit 118 is configured to acquire the fan operation signal Sf. As described above, the fan operation signal Sf is a signal indicating that the fan 40 is inoperable because the power supply 42 is unavailable. The fan operation signal Sf is input from the power supply 42 for operating the fan 40.

[0059] The second abnormality determination unit 120 is configured to perform an abnormality determination based on the fan operation signal Sf acquired by the fan operation signal acquisition unit 118. Specifically, the second abnormality determination unit 120 determines, based on the fan operation signal Sf, whether the fan 40 is in an unusable state when the gas turbine 1 is stopped. If the fan 40 is unusable, the air in the casing 70 cannot be agitated in the stopped gas turbine 1, and the temperature difference ΔT between the casing upper part 70 a and the casing lower part 70 b increases, which may cause a cat-back event. If a cat-back event occurs, there is a risk that the rotor 60 may interfere with the surrounding casing 70, and therefore an abnormality determination is made.

[0060] The second alarm output unit 122 is configured to output a second alarm W2 when an abnormality is determined by the second abnormality determination unit 120. If a cat-back event occurs, there is a risk that the rotor 60 may interfere with the surrounding casing 70 when a turning operation is performed in the stopped gas turbine 1. Therefore, when an abnormality is determined by the second abnormality determination unit 120, a second alarm W1 for prohibiting the turning operation is output, thereby urging the prohibition of the turning operation.

[0061] For example, the second alarm W2 may be a display signal for displaying a message on the display device 150 (see FIG. 8 ) that urges the operator to prohibit a turning operation. In this case, the display device 150 displays a message indicating that the turning operation should be prohibited based on the second alarm W2. Then, when the gas turbine 1 is turning while stopped, the operator who recognizes the display on the display device 150 can take appropriate action, such as stopping the turning operation.

[0062] The second alarm W2 may also be a control signal transmitted to the turning operation control unit 110 to prohibit the turning operation. In this case, the turning operation control unit 110 can automatically stop the turning operation being performed by the gas turbine 1 that is stopped by receiving the control signal (second alarm W2).

[0063] As described above, according to this embodiment, if there is a risk of a cat-back event occurring in the gas turbine 1 that is stopped and in which a turning operation is being performed, based on the temperature difference ΔT detected by the pair of temperature sensors 50 a, 50 b and the fan operation signal Sf, an abnormality is determined and an alarm to the effect that the turning operation is to be prohibited is output, thereby making it possible to respond appropriately to the cat-back event.

[0064] In addition, within the scope of the present disclosure, the components in the above-described embodiments may be replaced with well-known components as appropriate, and the above-described embodiments may be combined as appropriate.

[0065] The contents described in each of the above embodiments can be understood, for example, as follows.

[0066] (1) A gas turbine according to one embodiment includes: a compressor for generating compressed air; a combustor for mixing and burning the compressed air with fuel to generate combustion gas; a turbine that can be driven by the combustion gas; an exhaust duct for discharging exhaust gas from the turbine; at least one bleed line for guiding bleed air extracted from the compressor to the exhaust duct; at least one bleed valve provided in the at least one bleed line and switchable from an open state to a closed state by supply of control air; a control air supply system for supplying the control air; and an emergency air supply system for supplying emergency air to the at least one bleed valve in place of the control air when the control air system is unable to supply the control air.

[0067] According to the above aspect (1), when control air cannot be supplied to a bleed valve that can be switched from an open state to a closed state by supplying control air, emergency air can be supplied instead of control air. As a result, even when control air cannot be supplied due to the occurrence of a power outage (blackout), the bleed valve that is in an open state can be switched to a closed state using emergency air.

[0068] (2) In another aspect, in the aspect (1) above, the emergency air supply system comprises: an emergency air supply source capable of supplying the emergency air; an emergency air line for supplying the emergency air from the emergency air supply source to the at least one bleed valve; and a solenoid valve provided in the emergency air line, wherein the solenoid valve can be opened and closed by a power source independent of the control air supply system.

[0069] According to the above aspect (2), the solenoid valve operated when emergency air is supplied can be opened and closed by a power source (for example, a battery) independent of the control air supply system. As a result, even if the power source that supplies power to the control supply system experiences a power outage (blackout), the opening and closing operation of the bleed valve can be performed by operating the electromagnetic source using the independent power source.

[0070] (3) In another aspect, in the aspect (1) or (2), it is configured to determine whether or not the supply of control air is impossible by comparing an open / close command for the at least one bleed valve with the open / close state of the at least one bleed valve.

[0071] According to the above aspect (3), by comparing the opening / closing command for the bleed valve with the actual opening / closing state of the bleed valve, it is possible to suitably determine the supply of control air for performing the opening / closing operation of the bleed valve.

[0072] (4) In another aspect, in the aspect (3), the opening / closing command is set so that, after the gas turbine is stopped, the at least one bleed valve continues to be in an open state for a first period and then closes.

[0073] According to the above aspect (4), when the gas turbine is stopped, the bleed valve is opened and closed in accordance with the opening and closing command scheduled in this manner, and the bleed valve, which is in an open state to prevent surging, is switched to a closed state, thereby making it possible to effectively prevent a cat-back event.

[0074] (5) In another aspect, in the aspect (4) above, when the at least one bleed valve is controlled to be closed based on the opening / closing command, if the at least one bleed valve continues to be open for a second period longer than the first period, it is determined that the supply of control air is impossible.

[0075] According to the above aspect (5), by detecting that the bleed valve continues to be open at the time when the bleed valve should be closed based on the opening / closing command, it is possible to suitably determine that control air cannot be supplied.

[0076] (6) In another aspect, in the aspect (4), the at least one bleed line includes a plurality of bleed lines for extracting the bleed air having different pressures from each other from the compressor, the at least one bleed valve includes a plurality of bleed valves respectively provided in the plurality of bleed lines, and the opening / closing command is set to switch the plurality of bleed valves one by one from an open state to a closed state.

[0077] According to the above aspect (6), when the gas turbine is equipped with multiple bleed valves, these bleed valves are switched from the open state to the closed state one by one (at different times). This makes it possible to effectively open and close each bleed valve with a small amount of air and pressure. If all the bleed valves were closed simultaneously, the pressure loss in the system would increase, and there is a possibility that the pressure required to close each bleed valve would not be secured. This allows for a wider range of configurations to be selected for use as emergency air supply sources.

[0078] (7) In another aspect, in any one of the above aspects (1) to (6), the gas turbine further includes a fan that can be operated by a power source independent of the control air supply system and that stirs the air in the casing of the gas turbine.

[0079] According to the above aspect (7), even if the control air supply system is inoperable due to a power outage (blackout), the fan for stirring the air in the gas turbine casing can be operated by an independent power source. This eliminates the temperature difference between the air in the upper and lower parts of the casing when the gas turbine is stopped, making it possible to appropriately prevent the cat-back phenomenon.

[0080] (8) In another aspect, in any one of the aspects (1) to (7) above, the gas turbine includes at least a pair of temperature sensors for detecting a temperature difference between positions corresponding to different heights in a casing of the gas turbine, and a first alarm output unit for outputting a first alarm when the temperature difference detected by the at least a pair of temperature sensors becomes equal to or greater than a reference value when the gas turbine is stopped.

[0081] According to the aspect (8) above, when the gas turbine is stopped, if the temperature difference between positions corresponding to different heights in the casing of the gas turbine becomes equal to or greater than a reference value, a first alarm indicating this is output. When the gas turbine is stopped, a temperature difference occurs between the upper and lower parts of the casing due to convection of the atmosphere in the casing. If this temperature difference becomes large, a cat-back event may occur in which the casing is deformed due to the difference in the amount of thermal expansion between the upper and lower parts of the casing. Therefore, in this aspect, when the temperature difference detected by at least one pair of temperature sensors becomes equal to or greater than a reference value, a first alarm indicating the possibility of such a cat-back event is output, thereby urging an operator to take action to deal with the cat-back event or triggering automatic control to deal with the cat-back phenomenon.

[0082] (9) In another aspect, in the aspect (8), the first alarm indicates that a turning operation for driving the rotor to rotate at a predetermined rotation speed is prohibited when the gas turbine is stopped.

[0083] According to the above aspect (9), when the gas turbine is stopped, a turning operation is performed so that the rotor of the gas turbine is driven to rotate at a predetermined rotation speed, thereby preventing deformation of the rotor due to its own weight in the stopped gas turbine. If the temperature difference exceeds the reference value as described above, which raises concerns about a cat-back event, such a turning operation may cause the rotor to interfere with the surrounding casing, and therefore a first alarm is issued to notify the user that the turning operation should be prohibited. By issuing the first alarm in this manner, it is possible to effectively prevent the rotor from interfering with surrounding stationary members during the turning operation.

[0084] (10) In another aspect, in the aspect (8) or (9), the device further comprises a display device for displaying the first alarm.

[0085] According to the above aspect (10), by displaying the first alarm on the display device, an operator who views the display device can be made to recognize that a catback event may occur in the gas turbine 1 in an appropriate manner.

[0086] (11) In another aspect, in the aspect (7), a second alarm output unit is further provided for outputting a second alarm when the fan is inoperable.

[0087] According to the aspect (11) above, the fan that operates to prevent a cat-back event when the control air supply system is inoperable during shutdown of the gas turbine can be operated by a power source independent of the control air supply system as described above, but if the fan still falls into an inoperable state, a second alarm is output. This can prompt the operator to take action to respond to a cat-back event that occurs due to a temperature difference in the casing of the gas turbine that is shut down as a result of the fan becoming inoperable, or can trigger automatic control to respond to the cat-back event.

[0088] (12) In another aspect, in the aspect (11), the device further comprises a display device for displaying the second alarm.

[0089] According to the above aspect (12), by displaying the second alarm on the display device, an operator who views the display device can be made to recognize that a catback event may occur in the gas turbine 1 in an appropriate manner.

[0090] (13) A gas turbine control method according to one aspect is a gas turbine control method for controlling a gas turbine including: a compressor for generating compressed air; a combustor for mixing and burning the compressed air with fuel to generate combustion gas; a turbine that can be driven by the combustion gas; an exhaust duct for discharging exhaust gas from the turbine; at least one bleed air line for guiding bleed air extracted from the compressor to the exhaust duct; at least one bleed valve provided in the at least one bleed air line and switchable from a closed state to an open state by supply of control air; a control air supply system for supplying the control air; and an emergency air supply system for supplying emergency air to the at least one bleed air valve instead of the control air, the method comprising: determining whether the control air system can supply the control air; and, when it is determined that the control air system cannot supply the control air, supplying the emergency air to the bleed air valve instead of the control air.

[0091] According to the above aspect (13), when control air cannot be supplied to the bleed valve that can be switched from an open state to a closed state by the supply of control air, emergency air can be supplied instead of control air. As a result, even when the supply of control air cannot be made due to the occurrence of a power outage (blackout), the bleed valve that is in an open state can be switched to a closed state using emergency air.

[0092] REFERENCE SIGNS LIST 1 gas turbine 2 compressor 4 combustor 6 turbine 8 exhaust duct 10 fuel supply system 12 fuel supply line 14H high-pressure extraction line 14M medium-pressure extraction line 14L low-pressure extraction line 16 control air supply system 18 control air compressor 19 control air tank 20 control air supply line 21 dryer 22H1, 22M1, 22L1 first branch line 22H2, 22M2, 22L2 second branch line 24H, 24M, 24L volume tank 30 emergency air supply system 32 emergency air supply source 34 emergency air line 40 fan 42 power supply 50a, 50b temperature sensor 60 rotor 70 casing 70a upper casing 70b lower casing 100 control device 102 Bleed valve opening / closing command acquisition unit 104 Control air control unit 106 Supply state determination unit 108 Emergency air control unit 110 Turning operation control unit 112 Temperature difference acquisition unit 114 First abnormality determination unit 116 First alarm output unit 118 Fan operation signal acquisition unit 120 Second abnormality determination unit 122 Second alarm output unit 150 Display device VH High pressure bleed valve VM Medium pressure bleed valve VL Low pressure bleed valve Act Control air Aem Emergency air V1H, V1M, V1L Three-way valve S1H, S1M, S1L Solenoid valve S2H, S2M, S2L Solenoid valve VgH, VgM, VgL Check valve C Opening / closing command T1 First period T2 Second period Ta Upper compartment temperature Tb Lower compartment temperature Sf Fan operation signal W1 1st alarm W2 2nd alarm

Claims

1. A gas turbine comprising: a compressor for generating compressed air; a combustor for mixing and burning the compressed air with fuel to generate combustion gas; a turbine that can be driven by the combustion gas; an exhaust duct for discharging exhaust gas from the turbine; at least one bleed line for guiding bleed air extracted from the compressor to the exhaust duct; at least one bleed valve provided in the at least one bleed line and switchable from an open state to a closed state by a supply of control air; a control air supply system for supplying the control air; and an emergency air supply system for supplying emergency air instead of the control air to the at least one bleed valve when it is impossible to supply the control air by the control air system.

2. A gas turbine as described in claim 1, wherein the emergency air supply system comprises: an emergency air supply source capable of supplying the emergency air; an emergency air line for supplying the emergency air from the emergency air supply source to the at least one extraction valve; and a solenoid valve provided in the emergency air line, wherein the solenoid valve can be opened and closed by a power source independent of the control air supply system.

3. A gas turbine as described in claim 1 or 2, configured to determine whether or not the supply of control air is impossible by comparing an opening / closing command for the at least one bleed valve with the open / closed state of the at least one bleed valve.

4. The gas turbine according to claim 3, wherein the opening / closing command is set so that the at least one bleed valve is opened for a first period after the gas turbine is stopped, and then closed.

5. A gas turbine as described in claim 4, wherein when the at least one bleed valve is controlled to be closed based on the opening / closing command, if the at least one bleed valve continues to be open for a second period longer than the first period, it is determined that the supply of control air is impossible.

6. A gas turbine as claimed in claim 4, wherein the at least one bleed line includes a plurality of bleed lines for extracting the bleed air having different pressures from each other from the compressor, the at least one bleed valve includes a plurality of bleed valves respectively provided in each of the plurality of bleed lines, and the opening / closing command is set to switch the plurality of bleed valves one by one from an open state to a closed state.

7. A gas turbine according to claim 1 or 2, further comprising a fan operable by a power source independent of said control air supply system, for stirring air within the casing of said gas turbine.

8. A gas turbine as claimed in claim 1 or 2, comprising: at least a pair of temperature sensors for detecting a temperature difference between positions corresponding to different heights in a casing of the gas turbine; and a first alarm output unit for outputting a first alarm if the temperature difference detected by the at least a pair of temperature sensors becomes equal to or greater than a reference value when the gas turbine is stopped.

9. The gas turbine according to claim 8, wherein the first alarm indicates that a turning operation for driving the rotor to rotate at a predetermined rotation speed is to be prohibited when the gas turbine is stopped.

10. The gas turbine of claim 8, further comprising a display device for displaying said first alarm.

11. The gas turbine of claim 7, further comprising a second alarm output for outputting a second alarm if the fan is inoperable.

12. The gas turbine of claim 11, further comprising a display device for displaying said second alarm.

13. A gas turbine control method for controlling a gas turbine comprising: a compressor for generating compressed air; a combustor for mixing and burning the compressed air with fuel to generate combustion gas; a turbine capable of being driven by the combustion gas; an exhaust duct for discharging exhaust gas from the turbine; at least one bleed line for guiding bleed air extracted from the compressor to the exhaust duct; at least one bleed valve provided in the at least one bleed line and switchable from an open state to a closed state by a supply of control air; a control air supply system for supplying the control air; and an emergency air supply system for supplying emergency air instead of the control air to the at least one bleed valve, the gas turbine control method comprising: a step of determining whether the control air system can supply the control air; and a step of supplying the emergency air instead of the control air to the bleed valve when it is determined that the control air system cannot supply the control air.

Images