Fuel control device for a gas turbine

Abstract

The gas turbine includes: a compressor that generates compressed air; a combustor that uses the compressed air to burn fuel; and a turbine driven by combustion gases produced by the combustion of fuel in the combustor. The gas turbine is capable of switching between an operating mode in which the turbine drives an electric generator (i.e., a normal operating mode) and an operating mode in which the electric generator provides rotational power to the gas turbine (i.e., a reverse electric operation mode). The gas turbine's fuel control device includes: a first valve capable of adjusting the pressure of the fuel supplied to the combustor within a flow range of a first lower limit and a first upper limit; and a second valve capable of adjusting the pressure of the fuel supplied to the combustor within a flow range of a second lower limit greater than the first lower limit and a second upper limit greater than the first upper limit. When switching from the normal operating mode to the reverse electric operation mode, the adjustment target for adjusting the fuel pressure is changed from the second valve to the first valve before the fuel flow rate is reduced to the flow rate used in the reverse electric operation mode.

Description

Technical Field

[0001] This disclosure relates to a fuel control device for a gas turbine.

[0002] This application asserts priority based on Japan Patent Application No. 2021-051222 filed with the Japan Patent Office on March 25, 2021, the contents of which are incorporated herein by reference. Background Technology

[0003] For example, Patent Document 1 describes a technology for generating electricity by driving a generator with a gas turbine.

[0004] Regarding the fuel supply to the gas turbine, the aim is to achieve wide-range control from the fuel supply required at ignition to the fuel supply required at maximum output. Therefore, separate pressure regulating valves for small and large flow rates are typically used to adjust the pressure of the fuel supplied to the fuel nozzles. In this configuration, considering the stability of fuel supply control, the switch from the small to the large flow pressure regulating valve is generally performed in the transition region during acceleration after ignition. During no-load operation in the constant-speed operating region, fuel pressure control is achieved solely through the large flow pressure regulating valve.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-47728 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] However, when operating the gas turbine in a reverse electric operation mode, where the turbine is powered by an external power source, the fuel supply is smaller compared to no-load constant-speed operation. This may result in a situation where operation must occur near the switching point between the high-flow-rate pressure regulating valve and the low-flow-rate pressure regulating valve. If this switching occurs, there is a risk of unstable control due to discontinuous changes in the fuel supply caused by the valve's characteristics.

[0010] In view of the above, at least one embodiment of this disclosure aims to provide a fuel control device for a gas turbine that can appropriately control the fuel supply to the combustor of the gas turbine in a reverse electric operation mode.

[0011] Solution for solving the problem

[0012] To achieve the above objectives, a fuel control device for a gas turbine according to the present disclosure includes: a compressor that generates compressed air; a combustor that uses the compressed air to burn fuel; and a turbine driven by combustion gases generated by the combustion of the fuel in the combustor. The gas turbine is capable of switching between an operating mode in which the turbine drives an electric generator, i.e., a normal operating mode, and an operating mode in which the electric generator provides rotational power to the gas turbine, i.e., a reverse electric operating mode. The fuel control device includes: a first valve capable of adjusting the pressure of the fuel supplied to the combustor within a flow range of a first lower limit and a first upper limit; and a second valve capable of adjusting the pressure of the fuel supplied to the combustor within a flow range of a second lower limit greater than the first lower limit and a second upper limit greater than the first upper limit. When switching from the normal operating mode to the reverse electric operating mode, the adjustment target for adjusting the fuel pressure is changed from the second valve to the first valve before the fuel flow rate is reduced to the flow rate used in the reverse electric operating mode.

[0013] Furthermore, according to the fuel control device for a gas turbine disclosed herein, the gas turbine includes: a compressor that generates compressed air; a combustor that uses the compressed air to burn fuel; and a turbine driven by combustion gases generated by the combustion of the fuel in the combustor. The gas turbine is capable of switching between an operating mode in which the turbine drives an electric generator, i.e., a normal operating mode, and an operating mode in which the electric generator provides rotational power to the gas turbine, i.e., a reverse electric operating mode. The fuel control device includes a plurality of valves capable of adjusting the pressure of the fuel supplied to the combustor. In the normal operating mode, at least two of the plurality of valves are adjusted to adjust the fuel pressure. When switching from the normal operating mode to the reverse electric operating mode, the valve used to adjust the fuel pressure is changed to one of the plurality of valves before the fuel flow rate is reduced to the flow rate used in the reverse electric operating mode.

[0014] Invention Effects

[0015] According to the fuel control device for the gas turbine disclosed herein, the switching between the first valve and the second valve disappears during operation in reverse electric operation mode. As a result, the discontinuity of fuel supply based on valve characteristics disappears during operation in reverse electric operation mode, thus suppressing gas turbine operation variations and appropriately controlling the fuel supply to the burner. Attached Figure Description

[0016] Figure 1This is a structural diagram of a gas turbine system including a fuel control device for a gas turbine according to an embodiment of the present disclosure.

[0017] Figure 2 This is a structural diagram of a fuel control device for a gas turbine according to one embodiment of the present disclosure.

[0018] Figure 3 It is a schematic graph showing the valve characteristics of the first valve and the second valve of the fuel control device of a gas turbine provided in one embodiment of the present disclosure.

[0019] Figure 4 This is a timing diagram illustrating the operation of a fuel control device for a gas turbine according to one embodiment of the present disclosure. Detailed Implementation

[0020] Hereinafter, a fuel control device for a gas turbine according to an embodiment of the present disclosure will be described based on the accompanying drawings. The embodiments described below represent one aspect of the present disclosure and are not intended to limit the present disclosure; modifications can be made freely within the scope of the technical concept of the present disclosure.

[0021] <Structure of a fuel control device for a gas turbine according to one embodiment of this disclosure>

[0022] like Figure 1 As shown, the gas turbine system 10 includes a gas turbine 1, which has: a combustor 4 that burns fuel to generate combustion gases; a compressor 2 that supplies compressed air to the combustor 4 as combustion air; and a turbine 6 that has a rotating shaft 5 shared with the compressor 2 and is configured to be driven by the combustion gases generated by the combustor 4. An electric generator 7 is connected to the rotating shaft 5, and the electric generator 7 is configured to be electrically connected to an external power system 8 of the gas turbine 1. An inlet guide vane (IGV) 3A for adjusting the intake air volume is provided at the inlet of the compressor 2. The opening degree of the IGV 3A is configured to be adjustable by an actuator 3B (inlet guide vane control device). The actuator 3B is electrically connected to a control device 15.

[0023] The burner 4 is configured to be supplied with fuel from the fuel supply source 11 via the fuel supply line 12. A fuel control device 20 is provided on the fuel supply line 12 for regulating the flow rate (fuel supply amount) of the fuel supplied to the burner 4. Figure 2 This illustrates the structure of the fuel control device 20. Within the fuel control device 20, the fuel supply line 12 branches off to the burner 4 (see reference 4). Figure 1The main fuel supply line 21 and pilot fuel supply line 22 are connected to the main nozzle and pilot nozzle. The fuel control device 20 includes: a main fuel control valve 23, which is provided in the main fuel supply line 21 and is used to regulate the amount of fuel supplied to the main nozzle; a pilot fuel control valve 24, which is provided in the pilot fuel supply line 22 and is used to regulate the amount of fuel supplied to the pilot nozzle; differential pressure gauges 25 and 26, which detect the differential pressure between the upstream and downstream sides of the main fuel control valve 23 and the pilot fuel control valve 24 respectively; a first valve 27 and a second valve 28, which are differential pressure regulating valves, and are provided side by side in the main fuel supply line 21 at a position upstream of the main fuel control valve 23; and a differential pressure regulating valve 29, which is provided in the pilot fuel supply line 22 at a position upstream of the pilot fuel control valve 24.

[0024] The main fuel control valve 23 and the pilot fuel control valve 24 are electrically connected to the control device 15, and their openings are adjusted by the control device 15. The first valve 27, the second valve 28, and the differential pressure gauge 25 are also electrically connected to the control device 15, and their openings are adjusted by the control device 15 via PI control based on a setpoint of differential pressure. The differential pressure regulating valve 29 and the differential pressure gauge 26 are also electrically connected to the control device 15, and their openings are adjusted by the control device 15 via PI control based on a setpoint of differential pressure.

[0025] The control device 15 comprises, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. As an example, a series of processes for implementing various functions are stored in the storage medium as programs. The CPU reads this program into RAM and performs information processing / analysis, thereby implementing various functions. Alternatively, the program can be pre-installed in ROM or other storage media, provided in a state stored in a computer-readable storage medium, or distributed via wired or wireless communication. Computer-readable storage media include magnetic disks, optical disks, CD-ROMs, DVD-ROMs, and semiconductor memories.

[0026] In this embodiment, the opening degree of the first valve 27 and the relationship between the fuel flow rate and their respective valve characteristics are different. For example... Figure 3 As shown, the first valve 27 and the second valve 28 can respectively be at a minimum opening degree O min and maximum opening O max Control the fuel pressure between the openings, with the opening at the minimum opening (O). min The flow rate of fuel flowing in each valve is called the minimum flow rate F.1_min and F 2_min When the opening is the maximum opening O max The flow rate of fuel flowing in each valve at that time is called the maximum flow rate F. 1_max and F 2_max In this embodiment, F 1_min <F 2_min And F 1_max <F 2_max .

[0027] It should be noted that, in Figure 3 In the middle, the minimum opening degree O of the first valve 27 and the second valve 28 is respectively min They are the same, and their respective maximum openings O max They are the same, but they can also be different from each other. Furthermore, in Figure 3 In the middle, becoming F 1_max >F 2_min But it can also be F 1_max ≤F 2_min Moreover, in Figure 3 In this context, the slope of the valve characteristic of the first valve 27 is greater than the slope of the valve characteristic of the second valve 28, but the latter can also be greater than the former, or they can be the same. Moreover, the valve characteristics of the first valve 27 and the second valve 28 are linearly related, but they can also be represented by curves.

[0028] Operation of a gas turbine system according to one embodiment of this disclosure

[0029] Next, the operation of a gas turbine system 10 according to one embodiment of this disclosure will be described. Figure 1 As shown, the gas turbine system 10 can appropriately switch between the operating mode of the turbine 6 driving the electric generator 7, i.e., the normal operating mode, and the operating mode of the electric generator 7 providing rotational power to the gas turbine 1, i.e., the reverse electric operating mode.

[0030] In normal operation, compressed air is supplied from compressor 2 to burner 4, and fuel is supplied from fuel supply source 11 to burner 4 via fuel supply line 12, whereby the fuel is burned to generate combustion gases. These combustion gases are supplied to turbine 6, which is then driven to rotate. The rotation of turbine 6 is transmitted via rotating shaft 5 to electric generator 7, which acts as a generator. The electricity generated by electric generator 7 is transmitted to power system 8.

[0031] On the other hand, in the reverse electric operation mode, electricity is supplied from the external power system 8 of the gas turbine 1 to the electric generator 7, which then acts as a motor. The rotational power generated by the electric generator 7 is provided to the gas turbine 1 to assist its operation. Therefore, the reverse electric operation mode generally consumes less fuel than the normal operation mode.

[0032] Operation of a fuel control device for a gas turbine according to one embodiment of this disclosure.

[0033] Next, based on Figures 1-3 and Figure 4 The timing diagram illustrates the operation of the fuel control device 20 of the gas turbine 1. Figure 4 The timing diagram illustrates the time-dependent changes of various parameters in the gas turbine system 10 as it transitions from normal operating mode to reverse electric operating mode. Prior to time t0, the gas turbine system 10 operates in normal operating mode at a specified load L0. The operator of the gas turbine system 10 begins preparations at time t0 for the switch to reverse electric operating mode at time t2 (described later).

[0034] Based on the operator's operation at time t0, the control device 15 causes the fuel flow rate setpoint, which is used as a parameter in controlling the amount of fuel supplied to the burner 4, to change over time. As a result, the fuel supply amount F0 when the gas turbine system 10 is operating at load L0 is reduced to the minimum load L of the gas turbine system 10, which will be described later. min Fuel supply F under operating conditions min Furthermore, the control device 15 controls the main fuel control valve 23 and the pilot fuel control valve 24 based on the fuel flow setpoint and the pilot ratio setpoint, reducing the opening degree of each fuel control valve in a manner corresponding to the decrease in the fuel flow setpoint. Specifically, the control device 15 calculates the amount of fuel to be supplied to the main nozzle and the pilot nozzle based on the fuel flow setpoint and the pilot ratio, and transmits signals indicating the opening degree corresponding to each fuel supply amount to the main fuel control valve 23 and the pilot fuel control valve 24, respectively. The opening degree of the main fuel control valve 23 and the pilot fuel control valve 24 is controlled based on these signals. In addition, the opening degree of the second valve 28 and the differential pressure regulating valve 29 are adjusted respectively so that the detection values ​​of the differential pressure gauges 25 and 26 become the set values. Specifically, PI control is performed based on the difference between the detection value and the set value of each differential pressure gauge, thereby calculating an appropriate opening degree, and a signal indicating this opening degree is transmitted to the second valve 28 and the differential pressure regulating valve 29. In this way, by controlling the fuel supply to the burner 4 through the control device 15, while controlling the pressure of the fuel supplied to the main nozzle and the pilot nozzle, the fuel supply amount is adjusted from the initial fuel supply amount F0 to the minimum supply amount F (described later). minThe load on the gas turbine system 10 decreases, reaching its lowest load L at time t1. min Here, the minimum load L min The operation below is no-load constant speed operation, which means that the fuel supply to burner 4 in the normal operating mode is set to the minimum value, i.e., the minimum supply amount F. min It operates in a certain state.

[0035] In this embodiment, during the period from time t0 to time t2, the control device 15 maintains the opening of the first valve 27 at its initial opening degree O. 1_0 This causes the opening degree of the second valve 28 to change from the initial 0. 2_0 To become O at time t1 2_1 The pressure of the fuel supplied to the main nozzle is controlled to a set value by reducing the pressure of the fuel supplied to the main nozzle. Furthermore, at time t0, the fuel supply to both the main nozzle and the pilot nozzle is reduced, and the pilot ratio (the ratio of the fuel supply to the pilot nozzle to the fuel supply to the burner 4) increases from the initial pilot ratio R0. Thus, even with a reduced fuel supply to the burner 4, the burner 4 is less prone to misfire. Before time t1, the pilot ratio increases from R0 to R1. Moreover, at time t0, the control device 15 can adjust the opening of the IGV3A to a level that prevents misfire in the burner 4 by controlling the actuator 3B.

[0036] The operating conditions at time t1 are maintained from time t1 to time t2. The operating period from time t1 to time t2 is the time for receiving command signals from the operator or from other systems connected to the gas turbine system 10 regarding the switching of operating modes. At time t2, for example, the operator of the gas turbine system 10 presses the operating mode switching button, initiating the switch from the normal operating mode to the reverse electric operating mode. At time t2, the control device 15 maintains the fuel supply to the burner 4 at the minimum supply rate F. min The leader ratio begins to increase under the given state, and at time t3 the leader ratio is set to R2.

[0037] In order to maintain the fuel supply to burner 4 at the minimum supply rate F min Under the condition that the pilot ratio increases from R1 to R2, control device 15 decreases the opening of main fuel control valve 23 and increases the opening of pilot fuel control valve 24. At this time, control device 15, in order to make the detection value of differential pressure gauge 25 reach the set value, increases the opening of first valve 27 from time t2 to time t3, and decreases the opening of second valve 28 in a roughly synchronous manner. At time t3 when the pilot ratio reaches R2, the opening of second valve 28 decreases to 0. 2_2 The opening degree of the first valve 27 is increased to O.1_1 Additionally, the control device 15 can also control the actuator 3B during the period from time t2 to time t3 to control the opening degree of IGV3A to a degree suitable for reverse electric operation mode.

[0038] From time t3 to time t5, control device 15 controls the fuel flow rate setpoint to burner 4, causing the fuel supply to change from F... mmin Reduce the supply F for reverse power operation mode GM The control device 15 transmits signals indicating the opening degree to the main fuel control valve 23 and the pilot fuel control valve 24, respectively, based on the fuel flow setpoint and the pilot ratio. Furthermore, it adjusts the opening degree of the first valve 27 and the opening degree of the differential pressure regulating valve 29 in such a way that the detection values ​​of the differential pressure gauges 25 and 26 respectively become the target differential pressure setpoint.

[0039] Specifically, after time t3, control device 15 keeps the opening of the second valve 28 at 0. 2_2 The pressure difference between the upstream and downstream sides of the main fuel control valve 23 is adjusted solely by adjusting the opening of the first valve 27, thereby adjusting the pressure of the fuel supplied to the main nozzle. While in Figure 4 Not described in the text, but in the normal operating mode before time t0, the fuel supply to burner 4 is larger compared to the reverse electric operation mode. Therefore, the adjustment target for adjusting the pressure of the fuel supplied to the main nozzle is the second valve 28. Therefore, after time t3, the control device 15 changes the adjustment target for adjusting the pressure of the fuel supplied to the main nozzle from the second valve 28 to the first valve 27.

[0040] At time t4, the load on gas turbine system 10 becomes zero, but the fuel flow setpoint is further reduced, decreasing the fuel supply to combustor 4. After time t4, electricity is supplied from electrical system 8 to electric generator 7. Therefore, after time t4, electric generator 7 is driven as an electric motor, and the rotational power generated by electric generator 7 is supplied to gas turbine 1. At time t5, the fuel supply to combustor 4 reaches the fuel supply F required for reverse electric operation mode. GM The switching action to the reverse electric operation mode is completed. At this time, the opening degree of the first valve 27 is reduced to 0. 1_2 .exist Figure 4 In the middle, it becomes O 1_2 >O 1_0 However, according to the opening degree O of the first valve 27 in the normal operating mode 1_0 The size can become O 1_2 ≤O 1_0 .

[0041] In this embodiment, the pressure of the fuel supplied to the main nozzle in the reverse electric operation mode is adjusted only by adjusting the opening of the first valve 27. Therefore, in the reverse electric operation mode, the switching between the first valve 27 and the second valve 28 disappears, thereby eliminating the discontinuity in the fuel supply based on the valve characteristics. Thus, the operating fluctuations of the gas turbine 1 can be suppressed, and the fuel supply to the gas turbine 1 can be appropriately controlled during operation in the reverse electric operation mode.

[0042]

[0043] In this embodiment, the operation of changing the adjustment target for adjusting the pressure of fuel supplied to the main nozzle from the second valve 28 to the first valve 27 occurs before time t3, i.e., the load of the gas turbine system 10 decreases from the lowest load L. min This change is carried out before the reduction begins, but is not limited to this method. Such a change is only required if the fuel supply to burner 4 is reduced to F at least before time t5. GM The switching to the reverse electric operation mode can be performed before the operation is completed. Therefore, it can be performed before time t3, for example, before the fuel supply to burner 4 is reduced to the flow rate required for no-load constant speed operation, i.e., before time t1. In this way, the fuel supply to the gas turbine can be appropriately controlled during the switch from the normal operation mode to the reverse electric operation mode.

[0044] In this embodiment, when switching from the normal operating mode to the reverse electric operating mode, after making the opening of the first valve 27 larger than the normal operating mode opening and the opening of the second valve 28 smaller than the normal operating mode opening, the adjustment target for adjusting the fuel pressure changes from the second valve 28 to the first valve 27. However, this action is not a necessary structure. But by performing such an action, the fuel supply to the burner can be more appropriately controlled in the reverse electric operating mode.

[0045] In this embodiment, after the adjustment target for adjusting the pressure of fuel supplied to the main nozzle is changed from the second valve 28 to the first valve 27, the opening of the second valve 28 remains constant, but this is not a limitation. Alternatively, the opening of the second valve 28 may vary within a very narrow range, regardless of the adjustment of the pressure of fuel supplied to the main nozzle. However, if the opening of the second valve 28 is maintained at a constant value, the adjustment target for adjusting the pressure of fuel in the reverse electric operation mode becomes solely the first valve 27, thus enabling more appropriate control of the fuel supply to the burner 4 in the reverse electric operation mode.

[0046] In this embodiment, two valves with different characteristics, namely the first valve 27 and the second valve 28, are used as differential pressure regulating valves for adjusting the pressure of fuel supplied to the main nozzle. However, this is not a limitation, and two valves with the same characteristics can also be used. In this variation, in the normal operating mode, two valves are used to regulate the pressure of fuel supplied to the main nozzle, while in the reverse electric operation mode, only one valve is used to regulate the pressure of fuel supplied to the main nozzle. In this variation, the switching of the number of regulating valves also disappears in the reverse electric operation mode, thereby eliminating the discontinuity of fuel supply. Therefore, the operation fluctuations of the gas turbine 1 can be suppressed, and the fuel supply to the burner 4 can be appropriately controlled.

[0047] It should be noted that in this variation, the number of valves can be any number, not just two, but three or more. In this case, in the normal operating mode, at least two of the three or more valves are used to adjust the pressure of the fuel supplied to the main nozzle, while in the reverse electric operating mode, any one of the three or more valves is used to adjust the pressure of the fuel supplied to the main nozzle, thereby achieving the same effect.

[0048] In this embodiment, power is supplied from the power system 8 to the electric generator 7 during the reverse power operation mode, but this is not the only method. Excess power from other factories or the like can also be supplied to the electric generator 7.

[0049] In this embodiment, only the adjustment of the pressure of the fuel supplied to the main nozzle is described. However, by setting the differential pressure regulating valve 29 to a structure consisting of a first valve and a second valve and performing the same control, the pressure of the fuel supplied to the pilot nozzle can also be adjusted.

[0050] The contents described in the above embodiments are as follows.

[0051] [1] In one embodiment, the fuel control device for the gas turbine is the fuel control device (20) of the gas turbine (1), wherein,

[0052] The gas turbine (1) comprises: a compressor that generates compressed air (2); a combustor that uses the compressed air to burn fuel (4); and a turbine (6) driven by combustion gases generated by the combustion of the fuel in the combustor (4). The gas turbine (1) is capable of switching between an operating mode in which the turbine (6) drives an electric generator (7), i.e., a normal operating mode, and an operating mode in which the electric generator (7) provides the rotational power to the gas turbine (1), i.e., a reverse electric operating mode.

[0053] The fuel control device (20) includes:

[0054] The first valve (27) is capable of controlling the pressure of the fuel supplied to the burner (4) at a first lower limit (F). 1_min ) value and the first upper limit value (F) 1_max Adjust within the flow range; and

[0055] The second valve (28) is capable of controlling the pressure of the fuel supplied to the burner (4) at a level lower than the first lower limit value (F). 1_min The largest second lower limit (F) 2_min ) and the first upper limit value (F) 1_max The largest second upper limit value (F) 2_max Adjust within the flow range.

[0056] When switching from the normal operating mode to the reverse electric operating mode, the adjustment object for adjusting the fuel pressure is changed from the second valve (28) to the first valve (27) before the fuel flow rate is reduced to the flow rate used in the reverse electric operating mode.

[0057] According to the fuel control device for the gas turbine disclosed herein, the switching between the first valve and the second valve disappears during operation in reverse electric operation mode. As a result, the discontinuity of fuel supply based on valve characteristics disappears during operation in reverse electric operation mode, thus suppressing gas turbine operation variations and appropriately controlling the fuel supply to the burner.

[0058] [2] The fuel control device of the gas turbine in another scheme is based on the fuel control device of the gas turbine in [1].

[0059] When switching from the normal operating mode to the reverse electric operating mode, the fuel flow rate is reduced to the flow rate (F) required for no-load constant speed operation. min Before that, the adjustment object used to adjust the pressure of the fuel is changed from the second valve (28) to the first valve (27).

[0060] Based on this structure, even when switching from normal operating mode to reverse electric operating mode, the fuel supply to the burner can be properly controlled.

[0061] [3] Another gas turbine fuel control device is based on the gas turbine fuel control device of [1] or [2].

[0062] When switching from the normal operating mode to the reverse electric operating mode, after making the opening of the first valve (27) larger than that of the normal operating mode and the opening of the second valve (28) smaller than that of the normal operating mode, the adjustment object for adjusting the fuel pressure is changed from the second valve (28) to the first valve (27).

[0063] With this structure, the reduction in fuel flow at the first valve can be increased, thus enabling more appropriate control of the fuel supply to the burner in reverse electric operation mode.

[0064] [4] Another gas turbine fuel control device is based on the gas turbine fuel control device of any one of [1] to [3].

[0065] After the adjustment object used to adjust the pressure of the fuel is changed from the second valve (28) to the first valve (27), the opening of the second valve (28) is maintained at a constant value.

[0066] Based on this structure, the adjustment object that can be used to adjust the fuel pressure during operation in reverse electric mode is only the first valve, so the fuel supply to the burner can be more appropriately controlled during operation in reverse electric mode.

[0067] [5] In one scheme, the fuel control device for the gas turbine is the fuel control device (20) of the gas turbine (1), wherein,

[0068] The gas turbine (1) comprises: a compressor that generates compressed air (2); a combustor that uses the compressed air to burn fuel (4); and a turbine (6) driven by combustion gases generated by the combustion of the fuel in the combustor (4). The gas turbine (1) is capable of switching between an operating mode in which the turbine (6) drives an electric generator (7), i.e., a normal operating mode, and an operating mode in which the electric generator (7) provides the rotational power to the gas turbine (1), i.e., a reverse electric operating mode.

[0069] The fuel control device (20) includes multiple valves capable of adjusting the pressure of the fuel supplied to the burner (4).

[0070] In the normal operating mode, the adjustment objects used to adjust the fuel pressure are at least two of the plurality of valves.

[0071] When switching from the normal operating mode to the reverse electric operating mode, the adjustment object for adjusting the fuel pressure is changed to one of the plurality of valves before the fuel flow rate is reduced to the flow rate used in the reverse electric operating mode.

[0072] According to the fuel control device for the gas turbine disclosed herein, the switching between the first valve and the second valve disappears during operation in reverse electric operation mode. As a result, the discontinuity of fuel supply based on valve characteristics disappears during operation in reverse electric operation mode, thus suppressing gas turbine operation variations and appropriately controlling the fuel supply to the burner.

[0073] Explanation of reference numerals in the attached figures

[0074] 1…gas turbine;

[0075] 2…compressor;

[0076] 4…burner;

[0077] 6… Turbine;

[0078] 7…electric generator;

[0079] 10… Gas turbine system;

[0080] 20… Fuel control device;

[0081] 27…First valve;

[0082] 28…Second valve.

Claims

1. A fuel control device for a gas turbine, wherein, The gas turbine includes: a compressor that generates compressed air; a combustor that uses the compressed air to burn fuel; and a turbine driven by combustion gases produced by the combustion of the fuel in the combustor. The gas turbine is capable of switching between an operating mode in which the turbine drives an electric generator (i.e., a normal operating mode) and an operating mode in which the electric generator provides rotational power to the gas turbine (i.e., a reverse electric operation mode). The fuel control device includes: A first valve is capable of adjusting the pressure of the fuel supplied to the burner within a flow range of a first lower limit and a first upper limit; as well as The second valve is capable of adjusting the pressure of the fuel supplied to the burner within a flow range that is greater than the first lower limit and greater than the first upper limit. When switching from the normal operating mode to the reverse electric operating mode, after making the opening of the first valve larger than that of the normal operating mode and the opening of the second valve smaller than that of the normal operating mode, and before reducing the fuel flow rate to the flow rate used in the reverse electric operating mode, the adjustment target for adjusting the fuel pressure is changed from the second valve to the first valve.

2. The fuel control device for a gas turbine according to claim 1, wherein, When switching from the normal operating mode to the reverse electric operating mode, after making the opening of the first valve larger than that of the normal operating mode and the opening of the second valve smaller than that of the normal operating mode, and before reducing the fuel flow rate to the flow rate for no-load constant speed operation, the adjustment target for adjusting the fuel pressure is changed from the second valve to the first valve.

3. The fuel control device for a gas turbine according to claim 1 or 2, wherein, After changing the adjustment target for adjusting the fuel pressure from the second valve to the first valve, the opening of the second valve is maintained at a constant value.

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