Gas turbine control device, gas turbine control method, and program

Abstract

Even if a load reduction command signal is received while the fuel switching process is underway, the gas turbine can be returned to a stable operating state without incurring significant costs. [Solution] A fuel switching process is performed for a gas turbine that can switch the fuel to be burned between fuel gas and fuel oil while continuing to operate. If a load reduction command signal is received during the fuel switching process to reduce the load on the gas turbine, the fuel supply is stopped.

Description

Technical Field

[0001] The present disclosure relates to a control device for a gas turbine, a control method for a gas turbine, and a program.

Background Art

[0002] A dual-fuel fired gas turbine that can switch the fuel burned in a combustor between fuel gas and fuel oil while continuing operation is known. In this gas turbine, when switching the supplied fuel from fuel gas to fuel oil and when switching from fuel oil to fuel gas, the ratio of fuel gas to fuel oil is changed stepwise for the switching. Therefore, there is a timing when fuel gas and fuel oil are co-fired in the combustor. When a co-firing state occurs, combustion vibration may occur in the gas turbine. In order to suppress this combustion vibration, while performing the switching process of switching the fuel, the load of the gas turbine is reduced and maintained in a predetermined load range.

[0003] In addition, the switching process when switching from fuel oil to fuel gas includes a purge process of discharging the remaining fuel oil with water or air so that the fuel oil remaining in the nozzle does not coke after switching from fuel oil to fuel gas (see, for example, Patent Document 1). During the purge process, water or air is injected from the nozzle that injects fuel oil into the combustor where the combustion gas is burning, and thereby combustion vibration may occur. Therefore, even during the purge process, in order to suppress combustion vibration, the load of the gas turbine is maintained in a predetermined load range.

[0004] Incidentally, in gas turbines, processing is sometimes performed based on a load reduction command signal that lowers the load on the gas turbine. If this processing is performed while the load on the gas turbine is being maintained at a predetermined load range for fuel switching, the load on the gas turbine will move out of the predetermined load range. If the switching process is continued in this state, the likelihood of combustion vibrations occurring increases, so the switching process must be interrupted. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-059427 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, if the switching process is interrupted and the gas turbine enters a state such as the following, it will require significant costs to return the gas turbine to a stable operating state. Here, costs refer to human, time, or financial costs.

[0007] For example, in a combustor, if the switching process is interrupted while fuel gas and fuel oil are being mixed and combusted, the interrupted state is continued, and fuel is supplied based on the load reduction command signal. As a result, the gas turbine may become unstable. If this instability occurs, it will cost a great deal of money to restore the gas turbine to a stable operating state without damaging it.

[0008] For example, in a combustor, if the switching process is interrupted before or during the purging process described above, and fuel gas is supplied based on a load reduction command signal, residual fuel oil in the nozzle may coke and clog the nozzle. If the nozzle becomes clogged, the gas turbine cannot be restarted without replacing the nozzle, which will incur significant costs.

[0009] This disclosure is made in view of the above circumstances and aims to provide a gas turbine control device, a gas turbine control method, and a program that can return the gas turbine to a stable operating state without incurring significant costs, even if a load reduction command signal is received while the fuel switching process is in progress. [Means for solving the problem]

[0010] To solve the above problems, the gas turbine control device according to the present disclosure performs a fuel switching process to supply to a gas turbine that can switch the fuel to be burned to either fuel gas or fuel oil while continuing operation, and stops the supply of fuel if it receives a load reduction command signal to reduce the load on the gas turbine during the fuel switching process.

[0011] The gas turbine control method according to this disclosure performs a fuel switching process for a gas turbine that can switch the fuel to be burned between fuel gas and fuel oil while continuing operation, and if a load reduction command signal is received during the fuel switching process to reduce the load on the gas turbine, the fuel supply is stopped.

[0012] The program relating to this disclosure is a program for causing a computer to perform a procedure for performing a fuel switching process for a gas turbine that can switch the fuel to be burned while continuing operation between fuel gas and fuel oil, and a procedure for stopping the fuel supply if a load reduction command signal is received during the fuel switching process to reduce the load on the gas turbine. [Effects of the Invention]

[0013] According to the gas turbine control device, gas turbine control method, and program of this disclosure, even if a load reduction command signal is received while the fuel switching process is in progress, the gas turbine can be returned to a stable operating state without incurring significant costs. [Brief explanation of the drawing]

[0014] [Figure 1] This is a block diagram showing an example configuration of a gas turbine power plant according to the present disclosure. [Figure 2] This is a schematic diagram of a pilot nozzle and a main nozzle according to an embodiment of the present disclosure. [Figure 3] This flowchart shows an example of the operation of the fuel supply control unit when switching fuel according to the embodiment of this disclosure. [Figure 4] This flowchart shows an example of the operation of the signal processing unit according to the embodiment of this disclosure. [Figure 5] This is a schematic block diagram showing the configuration of a computer according to at least one embodiment. [Modes for carrying out the invention]

[0015] Hereinafter, the control device, gas turbine control method, and program of the gas turbine according to the embodiments of this disclosure will be described with reference to the figures. In each figure, the same or corresponding components are given the same reference numerals, and their descriptions will be omitted as appropriate.

[0016] (Example of a gas turbine power plant configuration) FIG. 1 is a block diagram showing a configuration example of a gas turbine power generation plant 1 according to an embodiment of the present disclosure. The gas turbine power generation plant 1 includes a control device 2, a fuel gas supply device 3, a fuel oil supply device 4, a water supply device 5, an air supply device 6, an electric meter 7, a gas turbine 10, flow control valves 33-P, 33-M, 34-P, 34-M, 35-P, 35-M, 36-P, 36-M, and discharge valves 39-P, 39-M. In FIG. 1, solid connection lines indicate the paths of pipes through which any of fuel gas, fuel oil, water, and air flow, and dotted connection lines indicate the paths of wiring through which electrical signals are transmitted and received.

[0017] The fuel gas supply device 3 stores fuel gas such as natural gas, for example, and supplies the fuel gas to the gas turbine 10 via the flow control valves 33-P, 33-M. The fuel oil supply device 4 stores fuel oil such as heavy oil, for example, and supplies the fuel oil to the gas turbine 10 via the flow control valves 34-P, 34-M.

[0018] The flow control valve 33-P is connected to the fuel gas supply device 3 via a pipe at one end and to the fuel supply path 43-P at the other end. The flow control valve 33-M is connected to the fuel gas supply device 3 via a pipe at one end and to the fuel supply path 43-M at the other end. The flow control valves 33-P, 33-M are electrically connected to the control device 2, and when receiving a valve opening degree command signal from the control device 2, they open and close the valves so as to reach the valve opening degree indicated by the received valve opening degree command signal, thereby adjusting the flow rate of the fuel gas.

[0019] The flow control valve 34-P is connected to the fuel oil supply device 4 via a pipe at one end and to the fuel supply path 44-P at the other end. The flow control valve 34-M is connected to the fuel oil supply device 4 via a pipe at one end and to the fuel supply path 44-M at the other end. The flow control valves 34-P, 34-M are electrically connected to the control device 2, and when receiving a valve opening degree command signal from the control device 2, they open and close the valves so as to reach the valve opening degree indicated by the received valve opening degree command signal, thereby adjusting the flow rate of the fuel oil.

[0020] The gas turbine 10 includes a compressor 11, a combustor 12, a turbine 13, a rotor 14, and a generator 15. The compressor 11 sucks in and compresses air from the outside due to the rotation of the rotor 14 that penetrates through the compressor 11 and the turbine 13, and the compressed air flows out to the combustor 12.

[0021] The combustor 12 includes an inner cylinder 16 of the combustor into which the air flowing out from the compressor 11 flows. The air flowing into the inner cylinder 16 of the combustor flows from the upper side of the inner cylinder 16 of the combustor to which the fuel supply paths 43-P, 43-M, 44-P, and 44-M are connected, toward the lower side of the inner cylinder 16 of the combustor provided with an opening through which combustion gas flows out toward the turbine 13.

[0022] As shown in FIG. ₂, the inner cylinder 16 of the combustor includes a pilot nozzle 50 and a main nozzle 60 inside. In FIG. ₂, the direction of the arrow indicated by the symbol AF is the direction in which air flows inside the inner cylinder 16 of the combustor (hereinafter referred to as the air flow direction AF). The pilot nozzle 50 and the main nozzle 60 have a shape with a longitudinal direction, and FIG.₂ is a view parallel to the longitudinal direction and including the central axis of each, and schematically shows a cross section when each of the pilot nozzle 50 and the main nozzle 60 is cut. The pilot nozzle 50 and the main nozzle 60 are arranged such that the longitudinal direction, that is, the direction of the central axis, is along the air flow direction AF of the inner cylinder 16 of the combustor.

[0023] The pilot nozzle 50 is connected to fuel supply lines 43-P and 44-P. The main nozzle 60 is connected to fuel supply lines 43-M and 44-M. Inside the pilot nozzle 50, there are two pipes connected to each of the fuel supply lines 43-P and 44-P. These pipes and the fuel supply lines 43-P and 44-P connected to each of these pipes are physically separate. However, for the sake of explanation, the pipe inside the pilot nozzle 50 connected to fuel supply line 43-P will be described as being included in fuel supply line 43-P, and the pipe inside the pilot nozzle 50 connected to fuel supply line 44-P will be described as being included in fuel supply line 44-P. Similarly, each of the pipes inside the main nozzle 60 will be described as being included in the fuel supply lines 43-M and 44-M connected to each of them.

[0024] The pilot nozzle 50 has injection holes 51-1 and 51-2 for fuel gas and an injection hole 52 for fuel oil. The fuel supply passage 43-P leads to injection holes 51-1 and 51-2, and the fuel supply passage 44-P leads to injection hole 52. Note that Figure 2 is a schematic diagram, and in reality, there are not only two injection holes for injecting fuel gas, but multiple injection holes, namely injection holes 51-1 and 51-2. However, here we will explain assuming that there are at least two injection holes 51-1 and 51-2.

[0025] The main nozzle 60 has injection holes 61-1 and 61-2 for fuel gas and injection holes 62-1 and 62-2 for fuel oil. The fuel supply passage 43-M leads to injection holes 61-1 and 61-2. The fuel supply passage 44-M leads to injection holes 62-1 and 62-2. Note that Figure 2 is a schematic diagram, and in reality, there are not limited to just two injection holes 61-1 and 61-2 for injecting fuel gas, but multiple injection holes. Similarly, there are not limited to just two injection holes 62-1 and 62-2 for injecting fuel oil, but multiple injection holes. However, here we will explain assuming that there are at least two injection holes 61-1 and 61-2 for fuel gas and at least two injection holes 62-1 and 62-2 for fuel oil.

[0026] Let's assume that fuel gas is supplied from fuel supply passages 43-P and 43-M. In this case, when fuel gas is injected from the injection holes 51-1 and 51-2 of the pilot nozzle 50 into the air flowing inside the combustor inner cylinder 16, the injected fuel gas burns. Furthermore, when fuel gas is injected from the injection holes 61-1 and 61-2 of the main nozzle 60 into the air flowing inside the combustor inner cylinder 16, the injected fuel gas burns using the flame obtained from the combustion of the fuel gas injected from injection holes 51-1 and 51-2 as a pilot ignition.

[0027] Let's assume that fuel oil is supplied from fuel supply passages 44-P and 44-M. In this case, when fuel oil is injected from the injection hole 52 of the pilot nozzle 50 into the air flowing inside the combustor inner cylinder 16, the injected fuel oil burns. Furthermore, when fuel oil is injected from the injection holes 62-1 and 62-2 of the main nozzle 60 into the air flowing inside the combustor inner cylinder 16, the injected fuel oil burns using the flame obtained from the combustion of the fuel oil injected from injection hole 52 as a pilot ignition.

[0028] Combustion gas generated in the combustor cylinder 16 by the combustion of fuel gas or fuel oil flows out through an opening provided at the bottom of the combustor cylinder 16. This flowing combustion gas enters the turbine 13, causing the rotor 14 to rotate, and the rotation of the rotor 14 generates electricity in the generator 15.

[0029] In Figure 2, one main nozzle 60 is shown to illustrate an example of the positional relationship between the pilot nozzle 50 and the main nozzle 60. However, generally, multiple main nozzles 60 are arranged around the pilot nozzle 50 in the combustor inner cylinder 16, with each of their longitudinal directions aligned with the direction of airflow AF. Each of the multiple main nozzles 60 is positioned such that, for example, the curved surface containing its central axis forms a cylinder, and the central axis of the formed cylinder coincides with the central axis of the pilot nozzle 50.

[0030] When the combustor inner cylinder 16 is equipped with multiple main nozzles 60, the multiple main nozzles 60 are divided into, for example, multiple groups, and the number of flow control valves 33-M, 34-M, 35-M, 36-M, fuel supply passages 43-M, 44-M, and discharge valves 39-M corresponds to the number of groups. Each of the fuel supply passages 43-M, 44-M assigned to one group branches out and connects to each of the multiple main nozzles 60 included in that group, supplying fuel gas, fuel oil, water, or air with flow rates regulated for each group.

[0031] When the fuel supplied to the combustor 12 is switched from fuel oil to fuel gas, high-temperature combustion gases generated by the combustion of fuel gases are present in the combustor inner cylinder 16. In this state, if fuel oil remains in the fuel supply passages 44-P and 44-M, this remaining fuel oil is exposed to the high-temperature combustion gases through the fuel oil injection holes 52 of the pilot nozzle 50 and the fuel oil injection holes 62-1 and 62-2 of the main nozzle 60. When fuel oil is exposed to high-temperature combustion gases, it cokes and solidifies, and the solidified fuel oil blocks the injection holes 52, 62-1, and 62-2. As a result, the pilot nozzle 50 and the main nozzle 60 become unusable.

[0032] To prevent coking of the fuel oil, a water supply device 5 and an air supply device 6 are provided. The water supply device 5 stores water for draining the fuel oil (hereinafter also referred to as purging water) and supplies water to the combustor 12 via flow control valves 35-P and 35-M. The air supply device 6 stores air for draining the fuel oil (hereinafter also referred to as purging air) and supplies air to the combustor 12 via flow control valves 36-P and 36-M.

[0033] The flow control valve 35-P is connected to the water supply device 5 via piping at one end and to the fuel supply line 44-P at the other end. The flow control valve 35-M is connected to the water supply device 5 via piping at one end and to the fuel supply line 44-M at the other end. The flow control valves 35-P and 35-M are electrically connected to the control device 2, and when they receive a valve opening command signal from the control device 2, they open and close the valves to the valve opening indicated in the received valve opening command signal, thereby adjusting the water flow rate.

[0034] The flow control valve 36-P is connected to the air supply device 6 via piping at one end and to the fuel supply line 44-P at the other end. The flow control valve 36-M is connected to the air supply device 6 via piping at one end and to the fuel supply line 44-M at the other end. The flow control valves 36-P and 36-M are electrically connected to the control device 2, and when they receive a valve opening command signal from the control device 2, they open and close the valves to the valve opening indicated in the received valve opening command signal, thereby adjusting the airflow rate.

[0035] The discharge valve 39-P is connected to the fuel supply passage 44-P at one end. The discharge valve 39-M is connected to the fuel supply passage 44-M at one end. The other ends of the discharge valves 39-P and 39-M are connected to a tank, for example, a tank (not shown) that stores the discharged fuel oil. Each of the discharge valves 39-P and 39-M is electrically connected to the control device 2. When the control device 2 receives a valve opening command signal, the valves are opened and closed to the valve opening indicated by the received valve opening command signal, thereby discharging the fuel oil remaining in the fuel supply passages 44-P and 44-M to which they are connected into the tank. Note that if the discharge valves 39-P and 39-M are opened while the gas turbine 10 is operating, combustion gases will flow back and be released to the outside. Therefore, while the gas turbine 10 is operating, the discharge valves 39-P and 39-M are always kept fully closed.

[0036] The power meter 7 measures the amount of power generated by the generator 15 at regular intervals, for example, and transmits the measured amount of power generated to the control device 2.

[0037] The control device 2 can be configured using, for example, a computer such as a server, personal computer, or microcomputer, and peripheral devices for that computer. Its functional configuration, consisting of a combination of hardware such as the computer and software such as programs executed by the computer, includes a fuel supply control unit 21 and a signal processing unit 22, as shown in Figure 1. The fuel supply control unit 21 performs various controls by transmitting valve opening command signals to the flow control valves 33-P, 33-M, 34-P, 34-M, 35-P, 35-M, 36-P, 36-M, and the discharge valves 39-P, 39-M. Examples of the various controls performed by the fuel supply control unit 21 include the controls shown below.

[0038] The fuel supply control unit 21 controls the fuel supplied to the combustor 12, switching between fuel gas and fuel oil, while the gas turbine 10 continues to operate. Generally, the main fuel supplied to the combustor 12 is fuel gas, and fuel oil is positioned as a backup fuel used in case of any problems with the supply or combustion of fuel gas. Therefore, control is performed to switch from fuel gas to fuel oil, and then, once the problem with fuel gas is resolved, control is performed to switch from fuel oil to fuel gas.

[0039] The fuel supply control unit 21 maintains a constant calorific value of the fuel supplied to the combustor 12 while proportionally distributing the calories between the fuel gas and fuel oil, and performing a stepwise switch when switching from fuel gas to fuel oil or from fuel oil to fuel gas. For example, when switching from fuel gas to fuel oil, the fuel supply control unit 21 gradually changes the ratio of calories of fuel gas to fuel oil from 100:0 to 70:30, 50:50, 30:70, and 0:100. In the intermediate states of the switch, such as 70:30, 50:50, and 30:70, the fuel gas and fuel oil are co-fired in the combustor 12. Theoretically, the combustion temperature should not increase because the calorific value of the fuel is maintained constant even during co-fired combustion. However, in reality, differences in the combustion state of fuel gas and fuel oil can cause the combustion state to become unstable, leading to an increase in combustion temperature and the occurrence of combustion oscillations.

[0040] When the fuel supply control unit 21 switches from fuel oil to fuel gas, it performs a purging process as part of the switching process from fuel oil to fuel gas. This process involves purging the fuel oil remaining in the fuel supply passages 44-P and 44-M using purging water and purging air.

[0041] When the fuel supply control unit 21 switches the fuel supplied to the combustor 12, it refers to the amount of power generated by the generator 15 measured by the power meter 7 and controls the load on the gas turbine 10 to be reduced and maintained within a predetermined load range. Here, the load on the gas turbine 10 refers to the output of the gas turbine 10, that is, the amount of power generated by the generator 15. The reason for reducing and maintaining the load on the gas turbine 10 within a predetermined load range is to lower the combustion temperature in the combustor 12. By lowering the combustion temperature in the combustor 12, combustion vibrations that occur when fuel gas and fuel oil are mixed and burned in the combustor 12, and combustion vibrations that occur when water or air for purging is supplied to the combustor 12, which is burning fuel gas, in order to discharge fuel oil, can be suppressed.

[0042] Hereinafter, the operating state in which the gas turbine 10 operates at a constant load while the load of the gas turbine 10 is reduced and maintained within a predetermined load range in order to switch fuels will be referred to as the second normal operating state. In contrast, the operating state in which the gas turbine 10 operates at a constant load that can obtain the required amount of power generation requested by, for example, a power transmission company will be referred to as the first normal operating state.

[0043] When the fuel supply control unit 21 receives a load reduction command signal, it interrupts the processing it is currently performing and controls the load on the gas turbine 10 to be reduced at a predetermined rate for each type of load reduction command signal, ultimately stopping the gas turbine 10. Here, a load reduction command signal is a command signal used, for example, when some kind of abnormality occurs in the gas turbine power plant 1. Examples of load reduction command signals include a runback command signal and an automatic stop command signal. The runback command signal and the automatic stop command signal have different load reduction rates, with the rate for the runback command signal predetermined to be higher than the rate for the automatic stop command signal.

[0044] When the fuel supply control unit 21 receives a trip command signal, it interrupts the processing it is currently performing, stops the fuel supply to the combustor 12, and controls the operation of the gas turbine 10 to shut it down. Here, a trip command signal is a command signal used, for example, when some kind of abnormality occurs in the gas turbine power plant 1 and it is necessary to shut down the gas turbine 10 as quickly as possible due to that abnormality.

[0045] The difference in the control of the fuel supply control unit 21 when a load reduction command signal is received and when a trip command signal is received can be shown in terms of the amount of fuel supplied to the combustor 12 as follows: When a load reduction command signal is received, the fuel supply control unit 21 gradually reduces the amount of fuel supplied to the combustor 12, and finally reduces the amount of fuel supplied to zero. Therefore, when a load reduction command is received, the fuel supply control unit 21 will continue to supply fuel to the combustor 12 for a while. In contrast, when a trip command signal is received, the fuel supply control unit 21 will not continue to supply fuel to the combustor 12 and will reduce the amount of fuel supplied to the combustor 12 to zero.

[0046] The signal processing unit 22 receives various command signals generated due to operations by the operator of the gas turbine power plant 1, and a switching completion signal output by the fuel supply control unit 21 indicating the completion of the switching process. All command signals given to the fuel supply control unit 21 are given to the fuel supply control unit 21 via the signal processing unit 22. Based on the signals received, the signal processing unit 22 determines whether the fuel supply control unit 21 is performing either a switching process to switch from fuel gas to fuel oil, or a switching process to switch from fuel oil to fuel gas. Hereinafter, when referring to either a switching process to switch from fuel gas to fuel oil, or a switching process to switch from fuel oil to fuel gas, the signal processing unit 22 will simply refer to it as "switching process" without any modifiers. When the fuel supply control unit 21 is performing a switching process, and the signal processing unit 22 receives a load reduction command signal to reduce the load on the gas turbine 10, it instructs the fuel supply control unit 21 to stop supplying fuel to the combustor 12.

[0047] (Processing by the control device) The processing performed by the control device 2 will be explained with reference to Figures 3 and 4.

[0048] (Switching process by the fuel supply control unit) Figure 3 is a flowchart showing the processing flow when the fuel supply control unit 21 receives a switching command signal from the signal processing unit 22. Here, the switching command signal is a signal that instructs the fuel supply control unit 21 to switch the fuel supplied to the combustor 12. The switching command signal is associated with either information indicating a switch from fuel gas to fuel oil, or information indicating a switch from fuel oil to fuel gas.

[0049] (Switching process from fuel gas to fuel oil) Referring to Figure 3, the processing when the fuel supply control unit 21 receives a switching command signal from the signal processing unit 22, which is associated with information indicating a switch from fuel gas to fuel oil, while the gas turbine 10 is in a fuel gas-fired state and in the first normal operating state, will be described. Since the gas turbine 10 is in a fuel gas-fired state and in the first normal operating state, the flow control valves 34-P, 34-M, 35-P, 35-M, 36-P, 36-M, and the discharge valves 39-P, 39-M are fully closed. The opening degree of the flow control valves 33-P, 33-M is set to the degree that sets the operating state of the gas turbine 10 to the first normal operating state.

[0050] When the fuel supply control unit 21 receives a switching command signal from the signal processing unit 22, it determines the type of switching command signal, that is, the information associated with the switching command signal (Sa1). In this case, since the switching command signal is associated with information indicating a switch from fuel gas to fuel oil, the fuel supply control unit 21 determines that the type of switching command signal is one that switches from fuel gas to fuel oil (Sa1, switch from fuel gas to fuel oil).

[0051] The fuel supply control unit 21 performs a process to reduce the load on the gas turbine 10 to a predetermined load range and maintain it at that range. That is, the fuel supply control unit 21 performs a process to transition the operating state of the gas turbine 10 from a first normal operating state to a second normal operating state. Based on the predetermined load range and the amount of power generated sequentially measured and output by the power meter 7, the fuel supply control unit 21 calculates the valve opening of each of the flow control valves 33-P and 33-M. The fuel supply control unit 21 transmits each of the valve opening command signals indicating the calculated valve opening to the respective flow control valves 33-P and 33-M. Each of the flow control valves 33-P and 33-M receives the valve opening command signal and adjusts its opening to match the valve opening indicated by the received valve opening command signal. The fuel supply control unit 21 repeatedly adjusts the opening of the flow control valves 33-P and 33-M until the load on the gas turbine 10, indicated by the amount of power generated sequentially measured and output by the power meter 7, reaches the predetermined load range (Sa2).

[0052] When the gas turbine 10 enters the second normal operating state, the fuel supply control unit 21 maintains the calorific value of the fuel supplied to the combustor 12 at that time, i.e., the calorific value in the second normal operating state, and proportionally distributes the calories between the fuel gas and the fuel oil, gradually switching from fuel gas to fuel oil.

[0053] The fuel supply control unit 21 calculates the valve openings corresponding to each of the flow control valves 33-P, 33-M, 34-P, and 34-M from the respective calorie values ​​of the fuel gas and fuel oil corresponding to each stage. The fuel supply control unit 21 generates four valve opening command signals, each representing one of the calculated valve openings, and transmits each of the four generated valve opening command signals to the corresponding flow control valves 33-P, 33-M, 34-P, and 34-M. The time between stages is predetermined, and the fuel supply control unit 21 waits for that time before transmitting the valve opening command signal corresponding to the next stage (Sa3).

[0054] When the flow control valves 33-P and 33-M are fully closed, the fuel supply control unit 21 outputs a switching completion signal (Sa10) to the signal processing unit 22, ending the switching process from fuel gas to fuel oil. After the processing of Sa10, a command signal to switch from the second normal operating state to the first normal operating state is given to the fuel supply control unit 21 via the signal processing unit 22, either by an operation by the operator of the gas turbine power plant 1 or otherwise.

[0055] When the fuel supply control unit 21 receives a command signal to transition from the second normal operating state to the first normal operating state, it repeatedly calculates the valve openings of the flow control valves 34-P and 34-M until the generator 15 is generating the required amount of power in the first normal operating state. Each time the valve opening is calculated, the fuel supply control unit 21 transmits a valve opening command signal indicating the calculated valve opening to the corresponding flow control valves 34-P and 34-M. As a result, the operating state of the gas turbine 10 transitions from the second normal operating state to the first normal operating state while using fuel oil.

[0056] (Switching process from fuel oil to fuel gas) Referring to Figure 3, the process will be explained starting with the case where the gas turbine 10 is in a fuel oil-fired state and in a first normal operating state, and the fuel supply control unit 21 receives a switching command signal from the signal processing unit 22 that is associated with information indicating a switch from fuel oil to fuel gas. Since the gas turbine 10 is in a fuel oil-fired state and in a first normal operating state, the flow control valves 33-P, 33-M, 35-P, 35-M, 36-P, 36-M, and the discharge valves 39-P, 39-M are fully closed. The opening degree of the flow control valves 34-P, 34-M is set to the degree that the operating state of the gas turbine 10 is set to the first normal operating state.

[0057] When the fuel supply control unit 21 receives a switching command signal from the signal processing unit 22, it determines the type of switching command signal, that is, the information associated with the switching command signal (Sa1). In this case, since the switching command signal is associated with information indicating a switch from fuel oil to fuel gas, the fuel supply control unit 21 determines that the type of switching command signal is one that switches from fuel oil to fuel gas (Sa1, switch from fuel oil to fuel gas).

[0058] The fuel supply control unit 21 performs the same process as in Sa2 described above, but with the flow control valve 33-P replaced with flow control valve 34-P and flow control valve 33-M replaced with flow control valve 34-M, in order to transition the operating state of the gas turbine 10 from the first normal operating state to the second normal operating state (Sa4). The fuel supply control unit 21 also performs the process in Sa3, but with the fuel gas replaced with fuel oil, in order to switch the fuel supplied to the combustor 12 from fuel oil to fuel gas (Sa5).

[0059] When the flow control valves 34-P and 34-M are fully closed, the fuel supply control unit 21 transmits a valve opening command signal to the flow control valves 35-P and 35-M, which are connected to the water supply device 5, indicating a predetermined valve opening, in order to open them. The predetermined valve opening for each of the flow control valves 35-P and 35-M may be a valve opening indicating full open, or it may be a valve opening corresponding to a predetermined flow rate of purging water. As a result, water is supplied from the water supply device 5 to the fuel supply passages 44-P and 44-M, and water is injected from the injection holes 52 of the pilot nozzle 50 and the injection holes 62-1 and 62-2 of the main nozzle 60, and the fuel oil remaining in the fuel supply passages 44-P and 44-M is discharged. When the predetermined time for supplying purge water has elapsed, the fuel supply control unit 21 transmits a valve opening command signal to the flow control valves 35-P and 35-M indicating a fully closed valve opening. As a result, the flow control valves 35-P and 35-M are fully closed, and the supply of purge water to the fuel supply passages 44-P and 44-M is stopped (Sa6).

[0060] When the flow control valves 35-P and 35-M are fully closed, the fuel supply control unit 21 transmits a valve opening command signal to the flow control valves 36-P and 36-M, which are connected to the air supply device 6, indicating a predetermined valve opening, in order to open them. The predetermined valve opening for each of the flow control valves 36-P and 36-M may be a valve opening indicating full open, or it may be a valve opening corresponding to a predetermined flow rate of purge air. As a result, air is supplied from the air supply device 6 to the fuel supply passages 44-P and 44-M, and air is injected from the injection holes 52 of the pilot nozzle 50 and the injection holes 62-1 and 62-2 of the main nozzle 60, and residual fuel oil and water in the fuel supply passages 44-P and 44-M are discharged. When the predetermined time for supplying purge air has elapsed, the fuel supply control unit 21 transmits a valve opening command signal to the flow control valves 36-P and 36-M indicating a fully closed valve opening. As a result, the flow control valves 36-P and 36-M are fully closed, and the supply of purge air to the fuel supply passages 44-P and 44-M is stopped (Sa7).

[0061] When the flow control valves 36-P and 36-M are fully closed, the fuel supply control unit 21 outputs a switching completion signal (Sa10) to the signal processing unit 22, ending the switching process from fuel oil to fuel gas. After the processing of Sa10, a command signal to switch from the second normal operating state to the first normal operating state is given to the fuel supply control unit 21 via the signal processing unit 22, either by an operation by the operator of the gas turbine power plant 1 or otherwise.

[0062] When the fuel supply control unit 21 receives a command signal to transition from the second normal operating state to the first normal operating state, it repeatedly calculates the valve openings of the flow control valves 33-P and 33-M until the generator 15 is generating the required amount of power in the first normal operating state. Each time the valve opening is calculated, the fuel supply control unit 21 transmits a valve opening command signal indicating the calculated valve opening to the corresponding flow control valves 33-P and 33-M. As a result, the operating state of the gas turbine 10 transitions from the second normal operating state to the first normal operating state while burning fuel gas.

[0063] (Processing by the signal processing unit) The processing by the signal processing unit 22 will be explained with reference to Figure 4. The internal memory area of ​​the signal processing unit 22 is reserved for a switching status flag that indicates whether or not the fuel supply control unit 21 is performing a switching process. The switching status flag indicates that the fuel supply control unit 21 is performing a switching process when it is "ON" and that it is not performing a switching process when it is "OFF". The initial state of the switching status flag is "OFF".

[0064] The signal processing unit 22 sequentially receives one of the following signals: various command signals generated due to operations by the operator of the gas turbine power plant 1, or the switching completion signal output by the fuel supply control unit 21 (Sb1). The signal processing unit 22 determines the type of signal received (Sb2).

[0065] Here, various command signals are pre-classified into types such as "switching command signals," "load reduction command signals," "command signals that are not rejected during the switching process," and "command signals that are rejected during the switching process."

[0066] As described above, a "switching command signal" is a switching command signal associated with either information indicating a switch from fuel gas to fuel oil, or information indicating a switch from fuel oil to fuel gas. A "load reduction command signal" is the load reduction command signal described above, and includes runback command signals and automatic stop command signals.

[0067] A "command signal that is not rejected during switching processing" is, for example, a command signal that causes the fuel supply control unit 21 to perform some kind of processing even while the fuel supply control unit 21 is performing switching processing, such as the trip command signal mentioned above.

[0068] A "command signal to be rejected during switching" is, for example, a command signal that, if given to the fuel supply control unit 21 while it is performing a switching process, will interfere with the fuel switching process. Examples of "command signals to be rejected during switching" include, for example, a command signal that increases the load on the gas turbine 10, such as the command signal that transitions from the second normal operating state to the first normal operating state described above.

[0069] The signal processing unit 22 determines that the type of signal it has received is a "switching command signal" (Sb2, switching command signal). In this case, the signal processing unit 22 determines whether the switching status flag in the internal memory area is "ON" or "OFF" (Sb3). If the signal processing unit 22 determines that the switching status flag is "OFF" (Sb3, OFF), it rewrites the switching status flag in the internal memory area to "ON" (Sb4). The signal processing unit outputs the received switching command signal to the fuel supply control unit 21 (Sb5), and then performs the process in Sb1 again.

[0070] On the other hand, if the signal processing unit 22 determines that the switching status flag is "ON" during the processing of Sb3 (Sb3, ON), it discards the received switching command signal (Sb6) and performs the processing of Sb1 again. The reason why the signal processing unit 22 discards the switching command signal is that if a new switching command signal is given to the fuel supply control unit 21 while the fuel switching process is in progress, there is a risk that some kind of trouble may occur in the switching process that is currently being executed.

[0071] In the processing of Sb2, the signal processing unit 22 determines that the type of signal it has received is a "switching completion signal" (Sb2, switching completion signal). In this case, the signal processing unit 22 rewrites the switching status flag in its internal memory area to "OFF" (Sb7) and then performs the processing of Sb1 again.

[0072] In the processing of Sb2, the signal processing unit 22 determines that the type of signal it has received is a "load drop command signal" (Sb2, load drop command signal). In this case, the signal processing unit 22 determines whether the switching status flag in the internal memory area is "ON" or "OFF" (Sb8). If the signal processing unit 22 determines that the switching status flag is "ON" (Sb8, ON), it discards the received command signal and outputs a trip command signal to the fuel supply control unit 21 in its place (Sb9), and then performs the processing of Sb1 again.

[0073] Meanwhile, if the signal processing unit 22 determines that the switching status flag is "OFF" during the processing of Sb8 (Sb8, OFF), it outputs the received command signal to the fuel supply control unit 21 (Sb10) and then performs the processing of Sb1 again.

[0074] In the processing of Sb2, the signal processing unit 22 determines that the type of signal it has received is a "command signal that will not be rejected during the switching process" (Sb2, command signal that will not be rejected during the switching process). In this case, the signal processing unit 22 outputs the received switching command signal to the fuel supply control unit 21 (Sb10), and then performs the processing of Sb1 again.

[0075] In the processing of Sb2, the signal processing unit 22 determines that the type of signal it has received is a "command signal to be rejected during switching processing" (Sb2, command signal to be rejected during switching processing). In this case, the signal processing unit 22 determines whether the switching status flag in the internal memory area is "ON" or "OFF" (Sb11). If the signal processing unit 22 determines that the switching status flag is "ON" (Sb11, ON), it discards the received command signal (Sb12) and performs the processing of Sb1 again.

[0076] Meanwhile, if the signal processing unit 22 determines that the switching status flag is "OFF" during the processing of Sb11 (Sb8, OFF), it outputs the received command signal to the fuel supply control unit 21 (Sb10) and then performs the processing of Sb1 again.

[0077] (Processing by the fuel supply control unit when a trip command signal is received) As explained with reference to Figure 4, when the signal processing unit 22 receives a trip command signal, it outputs the received trip command signal to the fuel supply control unit 21, regardless of whether the fuel supply control unit 21 is in the process of switching. Also, when the signal processing unit 22 receives a load reduction command signal, and the fuel supply control unit 21 is in the process of switching, it outputs the trip command signal to the fuel supply control unit 21 instead of the load reduction command signal.

[0078] When the fuel supply control unit 21 receives a trip command signal, it interrupts the process it is currently performing and stops the supply of fuel to the combustor 12. For example, when the fuel supply control unit 21 is performing the process of Sa2 shown in Figure 3 and receives a trip command signal from the signal processing unit 22, it sends a valve opening command signal indicating fully closed to the flow control valves 33-P and 33-M. When the fuel supply control unit 21 is performing the process of Sa4 shown in Figure 3 and receives a trip command signal from the signal processing unit 22, it sends a valve opening command signal indicating fully closed to the flow control valves 34-P and 34-M. When the fuel supply control unit 21 is performing the processes of Sa3 and Sa5 shown in Figure 3, i.e., the fuel switching process, and receives a trip command signal from the signal processing unit 22, it sends a valve opening command signal indicating fully closed to the flow control valves 33-P, 33-M, 34-P, and 34-M.

[0079] When the fuel supply control unit 21 is performing the process of Sa6 shown in Figure 3, that is, the process of supplying purge water to the combustor 12, and receives a trip command signal from the signal processing unit 22, it sends a valve opening command signal indicating full closure to the flow control valves 33-P, 33-M, 35-P, and 35-M.

[0080] When the fuel supply control unit 21 is performing the process of Sa7 shown in Figure 3, that is, the process of supplying purge air to the combustor 12, and receives a trip command signal from the signal processing unit 22, it sends a valve opening command signal indicating full closure to the flow control valves 33-P, 33-M, 36-P, and 36-M.

[0081] When the fuel supply control unit 21 receives a trip command signal from the signal processing unit 22, it outputs a switching completion signal to the signal processing unit 22. As a result, after the process shown in Sb7 in Figure 4, the switching status flag in the internal memory area of ​​the signal processing unit 22 is rewritten to "OFF", indicating that the fuel supply control unit 21 is not performing the switching process.

[0082] When the fuel supply control unit 21 stops supplying fuel to the combustor 12, the gas turbine 10 stops operating. If the fuel supply control unit 21 interrupts the processing of Sa4, Sa5, Sa6, and Sa7 and stops supplying fuel, fuel oil may remain in the fuel supply lines 44-P and 44-M. In this case, restarting the operation of the gas turbine 10 using fuel gas may cause coking to occur.

[0083] Therefore, the operator of the gas turbine power plant 1 opens the discharge valves 39-P and 39-M only after confirming that the gas turbine 10 has stopped operating. This operation sends a discharge valve open command signal to the signal processing unit 22. The signal processing unit 22 outputs the received discharge valve open command signal to the fuel supply control unit 21. Upon receiving the discharge valve open command signal, the fuel supply control unit 21 transmits a predetermined valve opening command signal to the discharge valves 39-P and 39-M. The predetermined valve opening for each of the discharge valves 39-P and 39-M may be a valve opening indicating full open, or a valve opening predetermined for the discharge of fuel oil.

[0084] By opening the discharge valves 39-P and 39-M, any fuel oil remaining in the fuel supply passages 44-P and 44-M is discharged through the discharge valves 39-P and 39-M. Once the discharge of the fuel oil remaining in the fuel supply passages 44-P and 44-M is complete, the operator of the gas turbine power plant 1 closes the discharge valves 39-P and 39-M. This operation sends a discharge valve closure command signal to the signal processing unit 22. The signal processing unit 22 outputs the received discharge valve closure command signal to the fuel supply control unit 21. Upon receiving the discharge valve closure command signal, the fuel supply control unit 21 transmits a valve opening command signal indicating full closure to the discharge valves 39-P and 39-M. As a result, the discharge valves 39-P and 39-M are fully closed.

[0085] When the discharge valves 39-P and 39-M are fully closed, the operator of the gas turbine power plant 1 opens the flow control valves 36-P and 36-M. This operation sends an air supply start command signal to the signal processing unit 22. The signal processing unit 22 outputs the received air supply start command signal to the fuel supply control unit 21. Upon receiving the air supply start command signal, the fuel supply control unit 21 performs the process shown in Sa7 of Figure 3. This allows any fuel oil remaining in the fuel supply passages 44-P and 44-M to be removed by air after the fuel oil has been discharged through the discharge valves 39-P and 39-M.

[0086] After supplying sufficient air to fuel supply lines 44-P and 44-M, the operator of the gas turbine power plant 1 closes the flow control valves 36-P and 36-M. This operation sends an air supply stop command signal to the signal processing unit 22. The signal processing unit 22 outputs the received air supply stop command signal to the fuel supply control unit 21. Upon receiving the air supply stop command signal, the fuel supply control unit 21 transmits a valve opening command signal indicating full closure to the flow control valves 36-P and 36-M. As a result, the flow control valves 36-P and 36-M are fully closed, and the supply of air to fuel supply lines 44-P and 44-M is stopped.

[0087] As a result, when the abnormality that occurred in the gas turbine power plant 1 is resolved and the operation of the gas turbine 10 is restarted, it is possible to ensure that coking does not occur even if the operation of the gas turbine 10 is restarted using fuel gas.

[0088] (Effects of the embodiment) In the above embodiment, as shown in the processing of Sb8 and Sb9 in Figure 4, when the signal processing unit 22 receives a load reduction command signal while the fuel supply control unit 21 is performing the switching process, the signal processing unit 22 outputs a trip command signal to the fuel supply control unit 21 in place of the load reduction command signal. Upon receiving the trip command signal, the fuel supply control unit 21 interrupts the switching process and stops supplying fuel to the combustor 12, and as a result, the gas turbine 10 stops.

[0089] This makes it possible to avoid supplying fuel based on the load reduction command signal at the timing when fuel gas and fuel oil are co-firing when switching from fuel gas to fuel oil and when switching from fuel oil to fuel gas, thereby preventing the gas turbine 10 from becoming unstable in operation.

[0090] Furthermore, when switching from fuel oil to fuel gas, even if the switching process is interrupted before the fuel oil remaining in the fuel supply lines 44-P and 44-M has been sufficiently discharged, the supply of fuel gas based on the load reduction command signal can be prevented. As a result, the fuel oil remaining in the fuel supply lines 44-P and 44-M will not be exposed to combustion gases generated by the combustion of fuel gas and will not coke, thus preventing blockage of the pilot nozzle 50 and the main nozzle 60.

[0091] When a trip command signal is given to the fuel supply control unit 21, the gas turbine 10 will be stopped, so it is necessary to return the gas turbine 10 to the operating state. However, returning from a stopped state to an operating state is a common practice for gas turbines 10, and it is possible to do so without making the operating state of the gas turbine 10 unstable. In addition, if fuel oil remains in the fuel supply passages 44-P and 44-M, as described above, the remaining fuel oil can be discharged through the discharge valves 39-P and 39-M, and further discharged by purging with air. Therefore, even if the operation of the gas turbine 10 is restarted by fuel gas firing, the pilot nozzle 50 and the main nozzle 60 will not be blocked by coking.

[0092] Therefore, even if a load reduction command signal is received while the fuel switching process is underway, the gas turbine 10 can be returned to a stable operating state without incurring significant costs.

[0093] (Supplemental configuration example of the embodiment) While embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include designs and other elements that do not depart from the gist of this disclosure.

[0094] In the above embodiment, when the signal processing unit 22 receives a load reduction command signal while the fuel supply control unit 21 is performing the switching process, the signal processing unit 22 outputs an existing trip command signal to the fuel supply control unit 21 in place of the load reduction command signal. Alternatively, a predetermined command signal may be defined separately from the trip command signal, and in the processing of Sb9, the signal processing unit 22 may output the predetermined command signal to the fuel supply control unit 21 in place of the load reduction command signal. Upon receiving the predetermined command signal, the fuel supply control unit 21 interrupts the processing it was performing at the time of receiving the signal and stops supplying fuel to the combustor 12, similar to when it receives a trip command signal.

[0095] When the fuel supply control unit 21 receives a predetermined command signal, it may further perform the following processing. For example, the fuel supply control unit 21 determines whether the interrupted process is a switching process to switch from fuel oil to fuel gas. If the fuel supply control unit 21 determines that the interrupted process is a switching process to switch from fuel oil to fuel gas, it transmits valve opening command signals to the discharge valves 39-P and 39-M and the flow control valves 36-P and 36-M connected to the air supply device 6 at predetermined intervals, which cause the discharge valves 39-P and 39-M to open and close, and then the flow control valves 36-P and 36-M connected to the air supply device 6 to open and close. This allows the fuel supply control unit 21 to autonomously discharge the fuel oil remaining in the fuel supply lines 44-P and 44-M, which would otherwise require operation by the operator of the gas turbine power plant 1 in the case of a trip command signal.

[0096] In the above embodiment, in the processing of Sb6 and Sb12 in Figure 4, the signal processing unit 22 discards the received command signals. However, since the switching process for switching fuels is underway, information indicating the reason for the discarding may be displayed on an output device of the control device 2 (not shown). This allows the operator of the gas turbine power plant 1 to understand why the command signals were not received.

[0097] In the above embodiment, an example is shown in which the gas turbine 10 is equipped with one combustor 12, but multiple combustors 12 may be arranged in a ring shape around the rotor 14. When multiple combustors 12 are provided, the processing of the above embodiment is performed in parallel in each of the multiple combustors 12.

[0098] (Computer configuration) Figure 5 is a schematic block diagram showing the configuration of a computer according to at least one embodiment. The computer 100 comprises a processor 101, main memory 102, storage 103, and interface 104. The control device 2 described above is implemented in the computer 100. The operation of each of the processing units described above, namely the fuel supply control unit 21 and the signal processing unit 22, is stored in the storage 103 in the form of a program. The processor 101 reads the program from the storage 103, loads it into the main memory 102, and executes the above processing according to the program. The processor 101 also reserves a storage area in the main memory 102 or storage 103 to store the switching status flag of the signal processing unit 22 described above, according to the program. The processor 101, in accordance with the program, connects the fuel supply control unit 21 to the flow control valves 33-P, 33-M, 34-P, 34-M, 35-P, 35-M, 36-P, 36-M, the discharge valves 39-P, 39-M, and the power meter 7 via the interface 104.

[0099] The program may be for implementing a part of the functions that the computer 100 is to perform. For example, the program may perform functions in combination with other programs already stored in the storage 103, or in combination with other programs implemented in other devices. In other embodiments, the computer may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to, or instead of, the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), FPGA (Field Programmable Gate Array), etc. In this case, some or all of the functions implemented by the processor may be implemented by the integrated circuit.

[0100] Examples of storage 103 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, magneto-optical disk, CD-ROM (Compact Disc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), and semiconductor memory. Storage 103 may be an internal medium directly connected to the bus of computer 100, or an external medium connected to computer 100 via interface 104 or a communication line. Furthermore, if this program is distributed to computer 100 via a communication line, computer 100 that receives the distribution may expand the program into main memory 102 and execute the above processing. In at least one embodiment, storage 103 is a tangible storage medium that is not temporary.

[0101] <Note> The control device 2 of the gas turbine 10 described in the embodiment of this disclosure can be understood, for example, as follows:

[0102] (1) The control device 2 of the gas turbine 10 according to the first embodiment performs a fuel switching process to supply to the gas turbine, which can switch the fuel to be burned to either fuel gas or fuel oil while continuing operation, and if it receives a load reduction command signal to reduce the load on the gas turbine during the fuel switching process, it stops the supply of the fuel. According to this embodiment and the following embodiments, even if a load reduction command signal is received while the fuel switching process is being performed, the gas turbine can be returned to a stable operating state without incurring significant costs.

[0103] (2) The control device 2 for the gas turbine 10 according to the second embodiment is the control device 2 of (1), comprising a fuel supply control unit 21 and a signal processing unit 22, wherein the fuel supply control unit performs a fuel switching process for the fuel supplied to the gas turbine, and if the signal processing unit receives the load reduction command signal during the fuel switching process, it outputs a trip command signal to the fuel supply control unit in place of the load reduction command signal, and if the fuel supply control unit receives the trip command signal during the fuel switching process, it interrupts the fuel switching process and stops the fuel supply. According to this embodiment, since the trip command signal that already exists as a command signal is reused to stop the fuel supply when the load reduction command signal is received during the fuel switching process, the cost required to improve the fuel supply control unit 21 can be reduced.

[0104] (3) The control device 2 for the gas turbine 10 according to the third embodiment is the control device 2 of (1) or (2), wherein the fuel switching process is a process of switching the fuel supplied to the gas turbine from fuel oil to fuel gas. According to this embodiment, when switching from fuel oil to fuel gas, the supply of fuel based on the load reduction command signal can be prevented at the timing when fuel oil and fuel gas are co-fired, so that the operating state of the gas turbine 10 does not become unstable.

[0105] (4) The control device 2 for the gas turbine 10 according to the fourth embodiment is the control device 2 of (3), wherein the fuel switching process includes a process of switching the fuel supplied to the gas turbine from fuel oil to fuel gas, and then discharging the fuel oil remaining in the fuel supply passage that supplies the fuel oil from the injection holes that inject the fuel oil. According to this embodiment, even if the switching process is interrupted before the fuel oil has been sufficiently discharged, the supply of fuel gas based on the load reduction command signal can be prevented. As a result, the fuel oil remaining in the fuel supply passages 44-P and 44-M is not exposed to combustion gases generated by the combustion of fuel gas and does not coke, thus preventing blockage of the pilot nozzle 50 and the main nozzle 60.

[0106] (5) The control device 2 for the gas turbine 10 according to the fifth embodiment is any one of the control devices 2 from (1) to (4), wherein the fuel switching process is a process of switching the fuel supplied to the gas turbine from fuel gas to fuel oil. According to this embodiment, when switching from fuel gas to fuel oil, the supply of fuel based on the load reduction command signal can be prevented at the timing when the fuel gas and fuel oil are co-fired, so that the operating state of the gas turbine 10 does not become unstable.

[0107] (6) The control device 2 for the gas turbine 10 according to the sixth embodiment is any one of the control devices 2 from (1) to (5), wherein the load reduction command signal is either a runback command signal or an automatic stop command signal. [Explanation of Symbols]

[0108] 1…Gas turbine power plant 2…Control device 3…Fuel gas supply device 4…Fuel oil supply device 5...Water supply device 6…Air supply device 7...Power meter 10... Gas turbine 11…Air compressor 12… Combustor 13... Turbine 14…Rota 15…Generator 16...Inner cylinder of the combustion chamber 21…Fuel supply control unit 22... Signal Processing Unit 33-P,33-M,34-P,34-M…Flow control valve 35-P,35-M,36-P,36-M…Flow control valve 39-P, 39-M… Discharge valves 50…Pilot nozzle 51-1,51-2,52…Injection hole 60... Main nozzle 61-1, 61-2, 62-1, 62-2… Injection holes

Claims

1. The fuel switching process is performed for a gas turbine that can switch the fuel being burned while continuing operation to either fuel gas or fuel oil. If a load reduction command signal is received during the fuel switching process to reduce the load on the gas turbine, the fuel supply is stopped. A control system for a gas turbine.

2. It comprises a fuel supply control unit and a signal processing unit, The fuel supply control unit, The fuel supply to the gas turbine is switched. The signal processing unit, If the load reduction command signal is received during the fuel switching process, a trip command signal is output to the fuel supply control unit in place of the load reduction command signal. The fuel supply control unit, If the trip command signal is received during the fuel switching process, the fuel switching process is interrupted and the fuel supply is stopped. The control device for a gas turbine according to claim 1.

3. The aforementioned fuel switching process is: This process involves switching the fuel supplied to the gas turbine from fuel oil to fuel gas. The control device for a gas turbine according to claim 1.

4. The fuel switching process includes: The process includes switching the fuel supplied to the gas turbine from fuel oil to fuel gas, and then discharging any fuel oil remaining in the fuel supply passage from the injection holes that inject the fuel oil. The control device for a gas turbine according to claim 3.

5. The aforementioned fuel switching process is: This process involves switching the fuel supplied to the gas turbine from fuel gas to fuel oil. The control device for a gas turbine according to claim 1.

6. The aforementioned load reduction command signal is It is either a runback command signal or an automatic stop command signal. A control device for a gas turbine according to any one of claims 1 to 5.

7. The fuel switching process is performed for a gas turbine that can switch the fuel being burned while continuing operation to either fuel gas or fuel oil. If a load reduction command signal is received during the fuel switching process to reduce the load on the gas turbine, the fuel supply is stopped. Gas turbine control methods.

8. On the computer, A procedure for performing a fuel switching process supplied to a gas turbine that can switch the fuel burned while continuing operation between fuel gas and fuel oil. If a load reduction command signal is received during the fuel switching process to reduce the load on the gas turbine, the procedure for stopping the fuel supply is as follows: A program to execute.

Images