Operation method for gas turbine, and control device for gas turbine

Abstract

To provide an operation method for a gas turbine that can reduce an increase in the amount of generation of unburned fuel.SOLUTION: An operation method for a gas turbine according to at least one embodiment of the present disclosure comprises a step of increasing a mixed combustion ratio of a first fuel whose mixed combustion ratio is desired to be increased, to a second fuel whose type is different from that of the first fuel. In the step of increasing the mixed combustion ratio, at least one of a turbine inlet temperature or a change rate of the mixed combustion ratio is changed on the basis of information on a relation between the turbine inlet temperature and the mixed combustion ratio.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for operating a gas turbine and a control device for the gas turbine. [Background technology]

[0002] BACKGROUND ART In a gas turbine, it is known to combust a plurality of types of fuel, such as low combustibility fuel and high combustibility fuel, in a combustor by changing the ratio of the supply amounts (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 149540 Summary of the Invention [Problem to be solved by the invention]

[0004] When combustors such as those described in the above-mentioned patent documents combustors change the ratio of the supply amounts of multiple types of fuels and combust them, the amount of unburned fuel generated may increase during the process of changing the ratio of the supply amounts depending on the type of fuel. The generation of unburned fuel leads to a decrease in the efficiency of the gas turbine. Therefore, it is desirable to minimize the amount of unburned fuel generated.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a gas turbine operation method and a gas turbine control device that can reduce an increase in the amount of unburned fuel generated. [Means for solving the problem]

[0006] (1) A method of operating a gas turbine according to at least one embodiment of the present disclosure, comprising: 1. A method of operating a gas turbine, comprising: increasing a mixed-combustion ratio of a first fuel whose mixed-combustion ratio is desired to be increased and a second fuel that is different from the first fuel; In the step of increasing the fuel-mixing ratio, at least one of the turbine inlet temperature or a rate of change of the fuel-mixing ratio is changed based on information relating to a relationship between the turbine inlet temperature and the fuel-mixing ratio.

[0007] (2) A method of operating a gas turbine according to at least one embodiment of the present disclosure, comprising: 1. A method of operating a gas turbine, comprising: increasing a mixed-combustion ratio of a first fuel whose mixed-combustion ratio is desired to be increased and a second fuel that is different from the first fuel; the gas turbine includes a sensor for detecting unburned fuel of the first fuel in combustion gas; In the step of increasing the mixed-combustion ratio, if it is determined that the concentration has increased based on the concentration of unburned fuel of the first fuel in the combustion gas detected by the sensor, at least one of the turbine inlet temperature or the rate of change of the mixed-combustion ratio is changed.

[0008] (3) A control device for a gas turbine according to at least one embodiment of the present disclosure includes: A control device for a gas turbine, comprising: a mixed-combustion ratio control unit configured to increase the mixed-combustion ratio of a first fuel whose mixed-combustion ratio is desired to be increased and a second fuel that is different from the first fuel, The fuel-mixing ratio control unit is configured to change at least one of the turbine inlet temperature or a rate of change of the fuel-mixing ratio based on information regarding a relationship between the turbine inlet temperature and the fuel-mixing ratio, when increasing the fuel-mixing ratio. [Effects of the Invention]

[0009] According to at least one embodiment of the present disclosure, an increase in the amount of unburned fuel generated can be reduced. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a gas turbine according to an embodiment. [Figure 2]FIG. 2 is a functional block diagram of a control device according to some embodiments. [Figure 3] 1 is a graph for explaining the relationship between the turbine inlet temperature and the mixed combustion ratio. [Figure 4] 1 is a flowchart illustrating a procedure for a process in a method for operating a gas turbine according to some embodiments. [Figure 5A] 4 is a graph showing the transition of the unburned ammonia concentration during the step of increasing the mixed-fuel ratio in the gas turbine operation method of the first embodiment. [Figure 5B] 4 is a graph showing the transition of the fuel-mixture ratio and the transition of the rate of change of the fuel-mixture ratio during the step of increasing the fuel-mixture ratio in the gas turbine operation method of the first embodiment. [Figure 5C] 4 is a graph showing a transition of an ammonia flow rate during the step of increasing the mixed-fuel ratio in the gas turbine operation method of the first embodiment. [Figure 5D] 4 is a graph showing a transition of the natural gas flow rate during the step of increasing the mixed-fuel ratio in the gas turbine operation method of the first embodiment. [Figure 5E] 4 is a graph showing a transition of the turbine inlet temperature during the step of increasing the fuel-fuel mixture ratio in the gas turbine operation method of the first embodiment. [Figure 6A] 10 is a graph showing the transition of the unburned ammonia concentration during the step of increasing the mixed-fuel ratio in the gas turbine operation method of the third embodiment. [Figure 6B] 10 is a graph showing the change in the rate of increase in the fuel-mixture ratio during the step of increasing the fuel-mixture ratio in the gas turbine operation method of the third embodiment. [Figure 6C] 10 is a graph showing a transition of the fuel-fuel mixture ratio during the step of increasing the fuel-fuel mixture ratio in the gas turbine operation method according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

[0012] (Overall configuration of gas turbine 2) An example of a gas turbine 2 including a gas turbine control device 100 according to some embodiments will be described below. FIG. 1 is a diagram schematically showing a configuration of a gas turbine 2 according to one embodiment. As shown in FIG. 1, the power generation device 1 includes the gas turbine 2 and a generator 7. In FIG. 1, the configuration relating to the gas turbine operating method described later is mainly illustrated, and other configurations are omitted.

[0013] The gas turbine 2 is, for example, a gas turbine for generating electricity. The gas turbine 2 includes a compressor 3 for generating compressed air, a combustor 4 for generating combustion gas using the compressed air and fuel, a turbine 5 configured to be rotationally driven by the combustion gas, and a fuel system 20 for supplying fuel to the combustor 4.

[0014] The compressor 3 is connected to the turbine 5 via a rotary shaft 8A. The compressor 3 is rotationally driven by the rotational energy of the turbine 5 to generate compressed air. An inlet guide vane 6 is provided on the inlet side of the compressor 3. The amount of air flowing in is adjusted by changing the opening of the inlet guide vane 6 using an actuator 6a. The opening of the inlet guide vane 6 is controlled based on an inlet guide vane opening control command IGVCSO. The compressed air generated by the compressor 3 is supplied to the combustor 4.

[0015] The combustor 4 is supplied with compressed air generated by the compressor 3 and fuel, and burns the fuel to generate combustion gas, which is a working fluid for the turbine 5. In the gas turbine 2 according to one embodiment, a first fuel F1 and a second fuel F2 different from the first fuel F1 can be combusted in the combustor 4.

[0016] The turbine 5 is driven by the combustion gas generated in the combustor 4. The turbine 5 is connected to the generator 7 by a rotary shaft 8B. The generator 7 is configured to generate electricity using the rotational energy of the turbine 5. An exhaust passage 5a of the turbine 5 is provided with a concentration sensor 9 for detecting the concentration of ammonia in the combustion gas.

[0017] (fuel system 20) In a gas turbine 2 according to one embodiment, a fuel system 20 is configured to supply a first fuel F1 and a second fuel F2, which is different from the first fuel F1, to a combustor 4. The fuel system 20 according to the one embodiment includes a first fuel supply system 21 for supplying the first fuel F1 to the combustor 4, and a second fuel supply system 22 for supplying the second fuel F2 to the combustor 4. In one embodiment of the gas turbine 2, the first fuel F1 is, for example, ammonia, and the second fuel F2 is, for example, natural gas, but the first fuel F1 may be a fuel other than ammonia, and the second fuel F2 may be a fuel other than natural gas as long as it is a different type of fuel from the first fuel F1.

[0018] The first fuel supply system 21 of the fuel system 20 according to one embodiment includes a first fuel flow rate control valve 23 for controlling the amount of the first fuel F1 supplied to the combustor 4. The second fuel supply system 22 of the fuel system 20 according to one embodiment includes a second fuel flow rate control valve 25 for controlling the amount of the second fuel F2 supplied to the combustor 4. The first fuel flow rate control valve 23 has an actuator (not shown) for adjusting the flow rate of the first fuel F1 flowing through the first fuel flow rate control valve 23. Similarly, the second fuel flow rate control valve 25 has an actuator (not shown) for adjusting the flow rate of the second fuel F2 flowing through the second fuel flow rate control valve 25. In the fuel system 20 according to one embodiment, actuators (not shown) of the first fuel flow rate control valve 23 and the second fuel flow rate control valve 24 are controlled by a control device 100 according to some embodiments.

[0019] (Control device 100) A control device 100 according to some embodiments includes a processor 101 that executes various types of arithmetic processing, and a memory 103 that non-temporarily or temporarily stores various types of data processed by the processor 101. The processor 101 is realized by a CPU, a GPU, an MPU, a DSP, various other arithmetic devices, or a combination thereof. The memory 103 is realized by a ROM, a RAM, a flash memory, or a combination thereof.

[0020] 2 is a functional block diagram of a control device 100 according to some embodiments. Note that in FIG. 2, only functional blocks related to the adjustment of the flow rates of the first fuel F1 and the second fuel F2, which will be described later, are shown, and other functional blocks are omitted. A control device 100 according to some embodiments includes a fuel-mixing ratio control unit 110 configured to increase the fuel-mixing ratio between a first fuel F1 whose fuel-mixing ratio is desired to be increased and a second fuel F2 that is different from the first fuel F1. The fuel-mixing ratio control unit 110 includes a fuel flow rate calculation unit 111 and a valve control signal output unit 112. The fuel-mixing ratio control unit 110, the fuel flow rate calculation unit 111, and the valve control signal output unit 112 are functional blocks implemented by the processor 101 executing a program stored in the memory 103. The fuel flow rate calculation unit 111 calculates the flow rates of the first fuel F1 and the second fuel F2 supplied to the combustor 4 from the first fuel supply system 21 and the second fuel supply system 22, as will be described later. The valve control signal output unit 112 outputs control signals to actuators (not shown) of the first fuel flow rate control valve 23 and the second fuel flow rate control valve 24 so that the first fuel F1 and the second fuel F2 are supplied to the combustor 4 at the flow rates calculated by the fuel flow rate calculation unit 111.

[0021] In the control device 100 according to some embodiments, the fuel-mixing ratio control unit 110 is configured to change at least one of the turbine inlet temperature T1T or the rate of change of the fuel-mixing ratio based on information about the relationship between the turbine inlet temperature T1T and the fuel-mixing ratio when increasing the fuel-mixing ratio, as will be described later. The specific processing contents in the control device 100 will be described in detail later.

[0022] (Regarding co-firing ratio control) In some embodiments, the gas turbine 2 is started by burning natural gas, i.e., the second fuel F2 exclusively. After the turbine inlet temperature T1T reaches a target temperature, the fuel supplied to the combustor 4 is switched to burning the first fuel F1 exclusively by decreasing the second fuel F2 and increasing the first fuel F1. That is, in the gas turbine 2 according to some embodiments, the mixed-combustion ratio (calorie ratio) of the first fuel F1 to all fuels supplied to the combustor 4 is gradually increased from 0% to 100% during the period from when the gas turbine 2 is started by the exclusive combustion of the second fuel F2 and the turbine inlet temperature T1T reaches a target temperature until the gas turbine 2 is switched to the exclusive combustion of the first fuel F1. In the present disclosure, the mixed-combustion ratio (calorie ratio) of the first fuel F1 to all fuels supplied to the combustor 4 will also be simply referred to as the mixed-combustion ratio.

[0023] FIG. 3 is a graph for explaining the relationship between the turbine inlet temperature and the co-firing ratio, with the horizontal axis representing the co-firing ratio and the vertical axis representing the turbine inlet temperature T1T. 3 is a graph line indicating the boundary between whether or not unburned fuel of ammonia, which is the first fuel F1, occurs in the combustion gas. In the following description, the unburned fuel of the first fuel F1 in the combustion gas will also be simply referred to as unburned fuel, and the concentration of unburned fuel of the first fuel F1 in the combustion gas will also be simply referred to as the concentration of unburned fuel.

[0024] The region to the lower right of graph line L2 in Fig. 3 is a region where unburned fuel occurs, and the region to the upper left of graph line L2 in Fig. 3 is a region where unburned fuel does not occur. Furthermore, in the region to the lower right of graph line L2 in Fig. 3, the concentration of unburned fuel increases the further away from graph line L2. The graph line L2 is a graph line obtained in advance by testing or the like. As described above, as a result of intensive research by the inventors, it was found that the relationship between the turbine inlet temperature T1T and the mixed combustion ratio affects the concentration of unburned fuel.

[0025] For example, as shown by the thick solid graph line L1 in the graph in Figure 3, if the mixed combustion ratio is increased while maintaining the turbine inlet temperature T1T at temperature Ta, when the mixed combustion ratio reaches value M1, graph line L1 will come into contact with graph line L2. If the co-firing ratio is further increased while maintaining the turbine inlet temperature T1T at temperature Ta, graph line L1 will reach the area to the lower right of graph line L2, as shown by the dashed line. Therefore, if the co-firing ratio exceeds value M1 when the turbine inlet temperature T1T is at temperature Ta, unburned fuel will be generated, and its concentration will gradually increase as the co-firing ratio increases.

[0026] As a result of careful investigations, the inventors have found that, when an increase in the amount of unburned fuel generated is expected in the process of increasing the fuel mix ratio as described above, the increase in the amount of unburned fuel generated can be reduced by either increasing the turbine inlet temperature T1T or decreasing the rate of change of the fuel mix ratio.

[0027] Therefore, in a gas turbine operation method according to some embodiments, as will be described later, in the process of increasing the fuel-mixture ratio, at least one of the turbine inlet temperature T1T or the rate of change of the fuel-mixture ratio is changed based on information about the relationship between the turbine inlet temperature T1T and the fuel-mixture ratio, as shown in the graph in FIG. 3. This can reduce the increase in the amount of unburned fuel produced. It is assumed that information relating to the relationship between the turbine inlet temperature T1T and the mixed combustion ratio, such as that shown in the graph of FIG.

[0028] The information on the relationship between the turbine inlet temperature T1T and the mixed combustion ratio, such as the graph shown in FIG. 3, may be a map of the turbine inlet temperature T1T and the mixed combustion ratio, such as the graph shown in FIG. This makes it relatively easy to control the rate of change of the turbine inlet temperature T1T and the fuel-fuel mixture ratio.

[0029] As described above, in the region to the lower right of graph line L2 in FIG. 3, the concentration of unburned fuel increases with distance from graph line L2. Therefore, information regarding the relationship between turbine inlet temperature T1T and the mixed-combustion ratio, as shown in the graph in FIG. 3, is also information regarding the relationship between turbine inlet temperature T1T, the mixed-combustion ratio, and the concentration of unburned fuel. Furthermore, information relating to the relationship between the turbine inlet temperature T1T and the mixed combustion ratio, such as the graph shown in FIG. 3, may be a function relating to the relationship between the turbine inlet temperature T1T, the mixed combustion ratio, and the concentration of unburned fuel. Therefore, in some embodiments of the gas turbine operation method, the increase in the amount of unburned fuel generated can be reduced by changing at least one of the turbine inlet temperature T1T or the rate of change of the fuel-fuel mixture ratio based on information related to the relationship between the turbine inlet temperature T1T, the fuel-fuel mixture ratio, and the concentration of unburned fuel, as shown in the graph in FIG. 3.

[0030] 4 is a flowchart showing the procedure of processing in a gas turbine operation method according to some embodiments. In the gas turbine operation method according to some embodiments, when the gas turbine 2 is started by burning only the second fuel F2 and the turbine inlet temperature T1T reaches a target temperature, the processor 101 of the control device 100 reads from the memory 103 and executes a program for executing the processing shown in the flowchart of FIG. A method for operating a gas turbine according to some embodiments includes a step S10 of increasing the mixed-fuel ratio. In some embodiments of the gas turbine operating method, step S10 of increasing the mixed-combustion ratio is a step of increasing the mixed-combustion ratio between a first fuel F1 whose mixed-combustion ratio is desired to be increased and a second fuel 2F that is different from the first fuel F1. The processing content of step S10 for increasing the mixed-fuel combustion ratio will be described below.

[0031] (Regarding the gas turbine operating method according to the first embodiment) FIG. 5A is a graph showing the transition of the concentration of unburned fuel, that is, the unburned ammonia concentration, during execution of step S10 of increasing the mixed-fuel ratio in the gas turbine operation method of the first embodiment. FIG. 5B is a graph showing the transition of the fuel-mixing ratio and the transition of the rate of change of the fuel-mixing ratio during execution of step S10 of increasing the fuel-mixing ratio in the gas turbine operation method of the first embodiment. FIG. 5C is a graph showing changes in the ammonia flow rate, which is the amount of the first fuel F1 supplied to the combustor 4, during execution of step S10 of increasing the mixed-fuel ratio in the gas turbine operation method according to the first embodiment. FIG. 5D is a graph showing changes in the natural gas flow rate, which is the amount of the second fuel F2 supplied to the combustor 4, during execution of step S10 of increasing the mixed-fuel ratio in the gas turbine operation method according to the first embodiment. FIG. 5E is a graph showing the transition of the turbine inlet temperature T1T during execution of step S10 of increasing the mixed-fuel ratio in the gas turbine operation method according to the first embodiment.

[0032] In the gas turbine operation method of the first embodiment, in step S10 of increasing the mixed-fuel ratio as described below, the turbine inlet temperature is changed based on information on the relationship between the turbine inlet temperature T1T and the mixed-fuel ratio as shown in the graph in FIG. 3 so that the concentration of unburned fuel in the combustion gas does not exceed a specified concentration. In the gas turbine operation method of the first embodiment, in step S10 of increasing the fuel-mixing ratio, the fuel-mixing ratio control unit 110 of the control device 100 increases the fuel-mixing ratio at a constant rate from the start to the end of step S10 of increasing the fuel-mixing ratio, that is, from a fuel-mixing ratio of 0% to 100%, as shown by graph lines L4 and L5 in FIG. 5B. In the gas turbine operation method of the first embodiment, the mixed combustion ratio reaches 100% when a time Te has elapsed since the start of step S10. For convenience of explanation, it is assumed that the turbine inlet temperature T1T at the start of step S10 of increasing the mixed combustion ratio is the temperature Ta in FIG.

[0033] In the gas turbine operation method of the first embodiment, in step S10 of increasing the mixed-fuel ratio, the fuel flow rate calculation unit 111 of the control device 100 calculates the flow rates of the first fuel F1 and the second fuel F2 supplied from the first fuel supply system 21 and the second fuel supply system 22 to the combustor 4 so that the mixed-fuel ratio increases at a constant rate while maintaining the turbine inlet temperature T1T at temperature Ta, as shown by graph line L8 in Fig. 5E. Then, the valve control signal output unit 112 of the control device 100 outputs control signals to actuators (not shown) of the first fuel flow rate control valve 23 and the second fuel flow rate control valve 24 so that the first fuel F1 and the second fuel F2 are supplied to the combustor 4 at the flow rates calculated by the fuel flow rate calculation unit 111. As a result, as shown by the graph line L6 in FIG. 5C, the ammonia flow rate, which is the supply amount of the first fuel F1 to the combustor 4, gradually increases over time, and as shown in FIG. 5D, the natural gas flow rate, which is the supply amount of the second fuel F2 to the combustor 4, gradually decreases over time. As a result, in the turbine 5, the co-firing ratio increases at a constant rate while the turbine inlet temperature T1T is maintained at the temperature Ta.

[0034] Dashed graph lines Lt1, Lt2, Lt3, and Lt4 in Fig. 5C are graph lines that show changes in the ammonia flow rate when the mix-firing ratio is increased at a constant rate while the turbine inlet temperature T1T is maintained at a certain temperature. Graph lines Lt1, Lt2, Lt3, and Lt4 each maintain a different turbine inlet temperature T1T, and the higher the graph line in Fig. 5C, the higher the maintained turbine inlet temperature T1T.

[0035] The dashed graph lines Lt5, Lt6, Lt7, and Lt8 in Fig. 5D represent changes in natural gas flow rate when the mix-firing ratio is increased at a constant rate while the turbine inlet temperature T1T is maintained at a certain temperature. The graph lines Lt5, Lt6, Lt7, and Lt8 each maintain a different turbine inlet temperature T1T, and the higher the graph line in Fig. 5D, the higher the maintained turbine inlet temperature T1T.

[0036] In the gas turbine operation method of the first embodiment, graph line L1 in Fig. 3 touches graph line L2 shortly after time T1 has elapsed since the start of step S10, which increases the fuel-fuel mixture ratio. That is, in the gas turbine operation method of the first embodiment, when step S10, which increases the fuel-fuel mixture ratio while maintaining the turbine inlet temperature T1T at temperature Ta, is performed, the fuel-fuel mixture ratio reaches value M1 in Fig. 3 shortly after time T1 has elapsed since the start of step S10. Therefore, shortly after time T1 has elapsed, unburned fuel begins to be generated, as indicated by the dashed line on graph line L3 in Fig. 5A.

[0037] Therefore, in the gas turbine operation method of the first embodiment, in step S10 of increasing the mixed-fuel ratio, a fuel flow rate calculation unit 111 calculates the flow rates of the first fuel F1 and the second fuel F2 supplied from the first fuel supply system 21 and the second fuel supply system 22 to the combustor 4 so as to gradually increase the turbine inlet temperature T1T so that the unburned fuel does not exceed a specified concentration. Then, a valve control signal output unit 112 of the control device 100 outputs control signals to actuators (not shown) of the first fuel flow rate control valve 23 and the second fuel flow rate control valve 24 so that the first fuel F1 and the second fuel F2 are supplied to the combustor 4 at the flow rates calculated by the fuel flow rate calculation unit 111. In the gas turbine operating method of the first embodiment, each unit is controlled so that the graph line L1 in FIG. 3 remains in the upper left region of the graph line L2.

[0038] In the gas turbine operating method of the first embodiment, in step S10 of increasing the fuel mix ratio, the fuel mix ratio control unit 110 of the control device 100 controls the turbine inlet temperature T1T to a first temperature when it determines that the concentration of unburned fuel will not exceed a specified concentration, for example, before time T1 has elapsed, based on information regarding the relationship between the turbine inlet temperature T1T and the fuel mix ratio, as shown in the graph of Fig. 3. In the step of increasing the fuel mix ratio, the fuel mix ratio control unit 110 of the control device 100 controls the turbine inlet temperature T1T to a second temperature higher than the first temperature when it determines that the concentration of unburned fuel is likely to exceed a specified concentration, for example, after time T1 has elapsed, based on the information. The first temperature may be, for example, the temperature Ta shown by the graph line L1 when the mixed combustion ratio is lower than the value M1 in Figure 3. The second temperature may be, for example, the temperature shown by the graph line L1 when the mixed combustion ratio is higher than the value M1 in Figure 3. The first temperature and the second temperature may be constant values ​​or may be variable values.

[0039] In the gas turbine operation method of the first embodiment, for example, by performing the control as described above, the turbine inlet temperature T1T can be gradually increased. Furthermore, according to the gas turbine operation method of the first embodiment, by increasing the turbine inlet temperature T1T, it is possible to prevent the concentration of unburned fuel in the combustion gas from exceeding a specified concentration, as shown by the solid line portion of the graph line L3 in FIG. 5A. 5A represents a state in which no unburned fuel is generated, but the solid line portion of the graph line L3 may be located in a region where the concentration is equal to or lower than the specified concentration. In the gas turbine operation method of the first embodiment, the graph line L1 may remain in the region above and to the left of the graph line L2 even after the mixed-fuel ratio reaches the value M1, as described above. This also applies to the gas turbine operation method of the second embodiment, which will be described later. As a result, before the mixed combustion ratio reaches value M1 in FIG. 3, as the mixed combustion ratio increases, the turbine inlet temperature T1T increases as shown by graph line L1, and even after the mixed combustion ratio reaches value M1, graph line L1 remains in the region to the upper left of graph line L2, preventing the generation of unburned fuel.

[0040] In the gas turbine operation method of the first embodiment, even if the graph line L1 is in the region to the lower right of the graph line L2 after the mixed-fuel ratio reaches the value M1, it is advisable to change the turbine inlet temperature T1T so that the graph line L1 does not enter a region where the concentration of unburned fuel is relatively high, that is, so that the graph line L1 does not enter a region relatively far from the graph line L2. This also applies to the gas turbine operation method of the second embodiment described later. This can reduce the increase in the amount of unburned fuel produced.

[0041] As an example of gradually increasing the turbine inlet temperature T1T, in the gas turbine operating method of the first embodiment, the fuel-mix ratio control unit 110 controls each unit so that the increase rate Sam of the flow rate of the first fuel F1 becomes a first increase rate Sam1 before the time T1 has elapsed, and controls each unit so that the increase rate Sam of the flow rate of the first fuel F1 becomes a second increase rate Sam2 that is greater than the first increase rate Sam1 after the time T1 has elapsed. As a result, the ammonia flow rate, which is the supply amount of the first fuel F1 to the combustor 4, increases at a faster rate after the time T1 has elapsed than before the time T1 has elapsed, as shown in FIG. 5C. Therefore, the turbine inlet temperature T1T can be gradually increased, and the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration.

[0042] Furthermore, as an example of gradually increasing the turbine inlet temperature T1T, in the gas turbine operating method of the first embodiment, the fuel mix ratio control unit 110 controls each unit so that the rate of decrease Sng of the flow rate of the second fuel F2 becomes a first rate of decrease Sng1 before the time T1 has elapsed, and controls each unit so that the rate of decrease Sng of the flow rate of the second fuel F2 becomes a second rate of decrease Sng2 that is smaller than the first rate of decrease Sng1 after the time T1 has elapsed. As a result, the natural gas flow rate, which is the supply amount of the second fuel F2 to the combustor 4, decreases at a slower rate after the time T1 has elapsed than before the time T1 has elapsed, as shown by the graph line L7 in FIG. 5D. Therefore, the turbine inlet temperature T1T can be gradually increased, and the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration. In the gas turbine operation method of the first embodiment, the second decrease rate Sng2, which is smaller than the first decrease rate Sng1, may become a negative value, as in the period from time T1 to time T2 in Fig. 5D, and may temporarily increase over time. However, even if the second decrease rate Sng2 becomes a negative value, it is desirable that at least the increase rate of the fuel-mixing ratio become a positive value, and in the gas turbine operation method of the first embodiment, it is desirable that the increase rate of the fuel-mixing ratio remain constant.

[0043] The above-mentioned control of changing the increase rate Sam of the flow rate of the first fuel F1 from the first increase rate Sam1 to the second increase rate Sam2 after the time T1 has elapsed and the control of changing the decrease rate Sng of the flow rate of the second fuel F2 from the first decrease rate Sng1 to the second decrease rate Sng2 after the time T1 has elapsed may be carried out simultaneously, or only one of them may be carried out.

[0044] When controlling the rate of increase Sam of the flow rate of the first fuel F1 and the rate of decrease Sng of the flow rate of the second fuel F2, the rate of increase of the mixed combustion ratio may be kept at a certain constant rate. That is, in step S10 of increasing the fuel mix ratio, if the fuel mix ratio control unit 110 of the control device 100 determines that the concentration of unburned fuel will not exceed a specified concentration based on information regarding the relationship between the turbine inlet temperature T1T and the fuel mix ratio, as shown in the graph in FIG. 3, the fuel mix ratio control unit 110 may set the increase rate Sam of the flow rate of the first fuel F1 to a first increase rate Sam1 and the decrease rate Sng of the flow rate of the second fuel F2 to a first decrease rate Sng1 so that the turbine inlet temperature T1T becomes the first temperature while maintaining the rate of change of the fuel mix ratio at the first rate of change. In step S10 of increasing the fuel mix ratio, if the fuel mix ratio control unit 110 of the control device 100 determines based on the above information that the concentration of unburned fuel is likely to exceed a specified concentration, the fuel mix ratio control unit 110 may set the increase rate Sam of the flow rate of the first fuel F1 to a second increase rate Sam2 that is greater than the first increase rate Sam1 and set the decrease rate Sng of the flow rate of the second fuel F2 to a second decrease rate Sng2 that is smaller than the first decrease rate Sng1, so that the turbine inlet temperature T1T becomes a second temperature that is higher than the first temperature while maintaining the rate of change of the fuel mix ratio at the first change rate. According to the gas turbine operating method of the first embodiment, the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration without changing the rate of change of the fuel-fuel mixture ratio.

[0045] In the gas turbine operation method of the first embodiment described above, the turbine inlet temperature T1T is gradually increased while the fuel mix ratio is increased at a constant rate. However, the turbine inlet temperature T1T may be gradually increased while the fuel mix ratio is increased while the rate of increase in the fuel mix ratio fluctuates.

[0046] After step S10 of increasing the fuel-mixing ratio is performed, the process proceeds to step S20, where the fuel-mixing ratio control unit 110 determines whether the fuel-mixing ratio has reached 100%. If the fuel-mixing ratio control unit 110 determines that the fuel-mixing ratio has not reached 100%, the process returns to step S10. When the mixed-fuel ratio control unit 110 determines that the mixed-fuel ratio has reached 100%, it ends the processing of this program.

[0047] (Regarding the gas turbine operating method according to the second embodiment) In the gas turbine operation method according to the first embodiment described above, the increase rate Sam of the flow rate of the first fuel F1 and the decrease rate Sng of the flow rate of the second fuel F2 are changed in order to increase the turbine inlet temperature T1T. In the gas turbine operating method according to the second embodiment, the opening degree of the inlet guide vanes 6 is reduced in order to increase the turbine inlet temperature T1T.

[0048] In the gas turbine operating method of the second embodiment, in step S10 of increasing the fuel mix ratio, the control device 100 controls each component to set the opening of the inlet guide vanes 6 to a first opening degree so that the turbine inlet temperature T1T becomes a first temperature when it is determined that the concentration of unburned fuel will not exceed a specified concentration, for example, as before the lapse of time T1, based on information about the relationship between the turbine inlet temperature T1T and the fuel mix ratio as shown in the graph of Fig. 3. That is, when it is determined that the concentration of unburned fuel will not exceed the specified concentration, the control device 100 calculates the opening degree (first opening degree) of the inlet guide vanes 6 so that the turbine inlet temperature T1T becomes the first temperature, and outputs a control signal to the actuator 6a to set the calculated opening degree (first opening degree).

[0049] In the gas turbine operating method of the second embodiment, in step S10 of increasing the mixed combustion ratio, if the control device 100 determines based on the above information that the concentration of unburned fuel is likely to exceed a specified concentration, for example, after the lapse of time T1, it controls each part to change the opening of the inlet guide vanes 6 to a second opening that is smaller than the first opening so that the turbine inlet temperature T1T becomes a second temperature that is higher than the first temperature. In other words, if the control device 100 determines that the concentration of unburned fuel is likely to exceed the specified concentration, it calculates the opening (second opening) of the inlet guide vanes 6 so that the turbine inlet temperature T1T becomes the second temperature, and outputs a control signal to the actuator 6a to change the calculated opening (second opening).

[0050] According to the gas turbine operating method of the second embodiment, the opening degree of the inlet guide vanes 6 is changed to prevent the concentration of unburned fuel in the combustion gas from exceeding a specified concentration.

[0051] In addition, in the gas turbine operation method of the second embodiment, it is also possible to change the increase rate Sam of the flow rate of the first fuel F1 and the decrease rate Sng of the flow rate of the second fuel F2 in order to increase the turbine inlet temperature T1T, as described in the gas turbine operation method of the first embodiment described above.

[0052] Another method of controlling the turbine inlet temperature T1T to be the second temperature is to reduce the amount of air flowing into the combustor 4 by bleeding air from the compressor 3. In this case, the bleeding air may be used to cool the turbine 5, for example, via a bleeding line 13 shown by a two-dot chain line in Figure 1. This makes it possible to prevent the concentration of unburned fuel in the combustion gas from exceeding a specified concentration.

[0053] Specifically, for example, the flow rate of the air flowing into the combustor 4 may be changed by adjusting the aperture of the bleed air amount control valve 27, which is provided in the bleed air line 13 shown in FIG. 1 and which adjusts the flow rate of the compressed air (bled air) flowing through the bleed air line 13. For example, in the gas turbine operating method of the second embodiment, in step S10 of increasing the mixed-fuel ratio, the control device 100 controls each part to set the aperture of the extraction air amount control valve 27 to the first aperture so that the turbine inlet temperature T1T becomes the first temperature when it is determined that the concentration of unburned fuel will not exceed a specified concentration, for example, as before the lapse of time T1, based on information about the relationship between the turbine inlet temperature T1T and the mixed-fuel ratio as shown in the graph of Fig. 3. That is, when it is determined that the concentration of unburned fuel will not exceed the specified concentration, the control device 100 calculates the aperture (first aperture) of the extraction air amount control valve 27 so that the turbine inlet temperature T1T becomes the first temperature, and outputs a control signal to an actuator (not shown) of the extraction air amount control valve 27 to set the calculated aperture (first aperture).

[0054] In the gas turbine operating method of the second embodiment, in step S10 of increasing the mixed combustion ratio, if the control device 100 determines based on the above information that the concentration of unburned fuel is likely to exceed a specified concentration, for example, after the lapse of time T1, it controls each part to change the aperture of the extraction air amount control valve 27 to a second aperture that is larger than the first aperture so that the turbine inlet temperature T1T becomes a second temperature that is higher than the first temperature. That is, if it determines that the concentration of unburned fuel is likely to exceed the specified concentration, the control device 100 calculates the aperture (second aperture) of the extraction air amount control valve 27 so that the turbine inlet temperature T1T becomes the second temperature, and outputs a control signal to an actuator (not shown) of the extraction air amount control valve 27 to change the calculated aperture (second aperture). The first and second opening degrees of the bleed air amount control valve 27 are opening degrees that are unrelated to the first and second opening degrees of the inlet guide vanes 6. The first opening degree of the bleed air amount control valve 27 can also include the case where the bleed air amount control valve 27 is fully closed.

[0055] According to the gas turbine operating method of the second embodiment, by changing the opening of the extraction amount adjustment valve 27, the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration.

[0056] (Regarding the gas turbine operating method according to the third embodiment) In the gas turbine operation methods according to the first and second embodiments described above, the turbine inlet temperature T1T is increased to reduce an increase in the amount of unburned fuel generated. In the gas turbine operating method according to the third embodiment, the increase rate of the mixed combustion ratio is reduced to reduce the increase in the amount of unburned fuel produced.

[0057] FIG. 6A is a graph showing the transition of the concentration of unburned fuel, that is, the unburned ammonia concentration, during execution of step S10 of increasing the mixed-fuel ratio in the gas turbine operation method of the third embodiment. FIG. 6B is a graph showing the change in the rate of increase in the fuel-mixing ratio during execution of step S10 of increasing the fuel-mixing ratio in the gas turbine operation method according to the third embodiment. FIG. 6C is a graph showing the transition of the fuel-fuel mixture ratio during execution of step S10 of increasing the fuel-fuel mixture ratio in the gas turbine operation method according to the third embodiment.

[0058] In an operating state where the fuel-mixing ratio is relatively high, the combustion of the first fuel F1, ammonia, tends to become unstable, and unburned fuel of the first fuel F1 is likely to occur. If the increase rate of the fuel-mixing ratio is relatively large in an operating state where the fuel-mixing ratio is relatively high, the combustion of the first fuel F1, ammonia, becomes more unstable, and the concentration of unburned fuel of the first fuel F1 in the combustion gas may increase. Therefore, in an operating state where the fuel-mixing ratio is relatively high, it is desirable to make the increase rate of the fuel-mixing ratio relatively small.

[0059] Therefore, in the gas turbine operation method of the third embodiment, in step S10 of increasing the fuel-mixture ratio, the control device 100 controls each unit so that the increase rate of the fuel-mixture ratio becomes a first increase rate when it is determined that the concentration of unburned fuel will not exceed a specified concentration, for example, as before time T1 has elapsed, based on information about the relationship between the turbine inlet temperature T1T and the fuel-mixture ratio as shown in the graph in FIG. 3 . In the gas turbine operation method of the third embodiment, in step S10 of increasing the mixed-fuel ratio, if the control device 100 determines based on the above information that the concentration of unburned fuel is likely to exceed a specified concentration, the control device 100 controls each part so that the rate of increase in the mixed-fuel ratio becomes a second increase rate that is smaller than the first increase rate.

[0060] That is, in the gas turbine operation method according to the third embodiment, when it is determined that the concentration of unburned fuel does not exceed a specified concentration, a fuel flow rate calculation unit 111 of the control device 100 calculates the flow rates of the first fuel F1 and the second fuel F2 supplied to the combustor 4 from the first fuel supply system 21 and the second fuel supply system 22 so that the increase rate of the mixed-fuel ratio becomes a first increase rate while maintaining the turbine inlet temperature T1T at the temperature Ta. Then, a valve control signal output unit 112 of the control device 100 outputs control signals to actuators (not shown) of the first fuel flow rate control valve 23 and the second fuel flow rate control valve 24 so that the first fuel F1 and the second fuel F2 are supplied to the combustor 4 at the flow rates calculated by the fuel flow rate calculation unit 111. As a result, for example, in the region where the co-firing ratio is smaller than value M1 in FIG. 3, the co-firing ratio increases at a certain rate (first increase rate) as shown by graph line L10 in FIG. 6B and graph line L11 in FIG. 6C before time T1 has elapsed.

[0061] In the gas turbine operation method of the third embodiment, when it is determined that the concentration of unburned fuel is about to exceed a specified concentration, a fuel flow rate calculation unit 111 of the control device 100 calculates the flow rates of the first fuel F1 and the second fuel F2 supplied to the combustor 4 from the first fuel supply system 21 and the second fuel supply system 22 so that the increase rate of the mixed-fuel ratio becomes a second increase rate that is smaller than the first increase rate, while maintaining the turbine inlet temperature T1T at the temperature Ta. Then, a valve control signal output unit 112 of the control device 100 outputs control signals to actuators (not shown) of the first fuel flow rate control valve 23 and the second fuel flow rate control valve 24 so that the first fuel F1 and the second fuel F2 are supplied to the combustor 4 at the flow rates calculated by the fuel flow rate calculation unit 111. As a result, for example, in the region where the co-firing ratio in FIG. 3 is greater than value M1, the rate of increase in the co-firing ratio after time T1 has elapsed is smaller than the rate of increase before time T1 has elapsed, as shown by graph line L10 in FIG. 6B and graph line L11 in FIG. 6C.

[0062] In the gas turbine operation method according to the third embodiment, for example, in the region where the mixed-combustion ratio exceeds value M1 in Fig. 3, graph line L1 is located in the region below and to the right of graph line L2, as shown by the dashed line in Fig. 3. Therefore, when the mixed-combustion ratio exceeds value M1, the concentration of unburned fuel (unburned ammonia concentration) gradually increases, as shown by graph line L9 in Fig. 6A after time T1 has elapsed. However, by reducing the increase rate of the mixed-combustion ratio, the combustion of the ammonia, which is the first fuel F1, is less likely to become unstable as described above, and therefore the increase in the concentration of unburned fuel can be reduced compared to when the increase rate of the mixed-combustion ratio is not reduced. Therefore, even if unburned fuel occurs, the concentration of unburned fuel can be prevented from exceeding the specified concentration.

[0063] In the gas turbine operation method of the third embodiment, the rate of increase in the fuel-mixing ratio is set to be smaller after time T1 than before time T1. In this case, a lower limit may be set for the rate of increase in the fuel-mixing ratio. That is, for example, as shown in FIG. 6B, the rate of increase in the fuel-mixing ratio may be gradually reduced from time T1 to time T3. After time T3 has passed, the fuel-mixing ratio at time T3 may be maintained until time Te has passed (i.e., until the fuel-mixing ratio reaches 100%). As described above, in the gas turbine operation method according to the third embodiment, if the control device 100 determines in step S10 of increasing the fuel mix ratio that the concentration of unburned fuel is likely to exceed a specified concentration based on information relating to the relationship between the turbine inlet temperature T1T and the fuel mix ratio as shown in the graph in FIG. 3, the control device 100 may control each component so that the rate of increase in the fuel mix ratio becomes a second rate of increase that is smaller than the first rate of increase and is equal to or greater than a predetermined lower limit. This makes it possible to increase the mixed combustion ratio in a relatively short time while reducing the increase in the amount of unburned fuel generated.

[0064] The lower limit value is preferably a positive value, which makes it possible to increase the mixed combustion ratio in a relatively short time while suppressing an increase in the amount of unburned fuel generated. The lower limit may be a negative value. In other words, the rate of increase in the co-firing ratio may be a negative value. This may take some time to bring the co-firing ratio closer to 100%, but it may be possible to further reduce the increase in the amount of unburned fuel generated.

[0065] In this way, the rate of increase in the mixed combustion ratio may be made negative, i.e., the rate of increase in the supply amount of the first fuel F1 may be temporarily made greater than the rate of increase in the supply amount of the second fuel F2. In cases where it is difficult to reduce the amount of unburned fuel emissions, the amount of unburned fuel generated can be reduced by operating the fuel system 20 to temporarily lower the mixed combustion ratio.

[0066] (Regarding the gas turbine operating method according to the fourth embodiment) In the gas turbine operation methods according to the first to third embodiments described above, in step S10 of increasing the mixed-fuel ratio, the process is performed without using the concentration sensor 9 for detecting the ammonia concentration in the combustion gas. In the gas turbine operating method according to the fourth embodiment, processing using the concentration sensor 9 is performed in step S10 of increasing the mixed-fuel combustion ratio.

[0067] Specifically, in the gas turbine operation method according to the fourth embodiment, the control device 100 refers to the detected value of the ammonia concentration in the combustion gas by the concentration sensor 9 when determining that the concentration of unburned fuel will not exceed a specified concentration in step S10 of increasing the mixed-fuel ratio, and when determining that the concentration of unburned fuel is likely to exceed the specified concentration. For example, if the concentration sensor 9 cannot detect ammonia, the control device 100 may determine that the concentration of unburned fuel will not exceed a specified concentration. Alternatively, if the detected value of ammonia by the concentration sensor 9 exceeds a predetermined threshold, the control device 100 may determine that the concentration of unburned fuel is likely to exceed a specified concentration.

[0068] Furthermore, for example, in the control for changing the rate of increase Sam of the flow rate of the first fuel F1 or the control for changing the rate of decrease Sng of the flow rate of the second fuel F2 in the first embodiment described above, feedback control based on the detected value of ammonia by the concentration sensor 9 may be performed. For example, in the second embodiment described above, when the opening degree of the inlet guide vanes 6 is changed, feedback control based on the detected value of ammonia by the concentration sensor 9 may be performed. For example, in the third embodiment described above, when changing the rate of increase in the mixed-fuel combustion ratio, feedback control based on the ammonia detection value by the concentration sensor 9 may be performed.

[0069] As described above, in the gas turbine operation method of the fourth embodiment, in step S10 of increasing the mixed-fuel ratio, if it is determined that the concentration has increased based on the concentration of unburned fuel of the first fuel F1 in the combustion gas detected by the concentration sensor 9, the control device 100 changes at least one of the turbine inlet temperature T1T or the rate of change of the mixed-fuel ratio. This can reduce the increase in the amount of unburned fuel produced.

[0070] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications. Furthermore, if the mixed combustion ratio is gradually increased by increasing the first fuel F1 while decreasing the second fuel F2, at a certain point a combustion field will be formed in which flame stabilization is possible with only the first fuel F1 (independent flame stabilization is possible with the first fuel F1). Therefore, in the process of increasing the fuel mix ratio, the timing to start changing at least one of the turbine inlet temperature T1T or the rate of change of the fuel mix ratio may be after the point at which flame stabilization is possible with only the first fuel F1, as described above. This allows stable combustion with only the first fuel F1, reducing the possibility of misfires and making it easier to change conditions such as changing the turbine inlet temperature T1T or the rate of change of the fuel mix ratio.

[0071] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A method for operating a gas turbine according to at least one embodiment of the present disclosure is a method for operating a gas turbine 2, and includes step S10 of increasing a fuel-fuel mix ratio between a first fuel F1 for which an increase in the fuel-fuel mix ratio is desired and a second fuel F2 that is different from the first fuel F1. In step S10 of increasing the fuel-fuel mix ratio, at least one of the turbine inlet temperature T1T or the rate of change of the fuel-fuel mix ratio is changed based on information regarding the relationship between the turbine inlet temperature T1T and the fuel-fuel mix ratio.

[0072] As a result of extensive research by the inventors, it was found that when an increase in the amount of unburned fuel generated is expected in the process of increasing the mixed combustion ratio, the increase in the amount of unburned fuel generated can be reduced by changing the turbine inlet temperature T1T or by changing the rate of change of the mixed combustion ratio. According to the method (1) above, the increase in the amount of unburned fuel generated can be reduced.

[0073] (2) In some embodiments, in the method of (1) above, the information may be information regarding the relationship between the turbine inlet temperature T1T, the mixed combustion ratio, and the concentration of unburned fuel of the first fuel F1 in the combustion gas.

[0074] As a result of extensive research, the inventors have found that the relationship between the turbine inlet temperature T1T and the above-mentioned mixed combustion ratio affects the concentration of unburned fuel of the first fuel F1 in the combustion gas. According to the method (2) above, by changing at least one of the turbine inlet temperature T1T or the rate of change of the mixed combustion ratio based on the information, it is possible to reduce an increase in the amount of unburned fuel produced.

[0075] (3) In some embodiments, in the method of (2) above, in step S10 of increasing the mixed-fuel ratio, the turbine inlet temperature T1T may be changed based on the above information so that the concentration of unburned fuel in the combustion gas does not exceed a specified concentration.

[0076] According to the above method (3), the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration by changing the turbine inlet temperature T1T.

[0077] (4) In some embodiments, in the method of (3) above, in step S10 of increasing the mixed combustion ratio, if it is determined based on the information that the concentration of unburned fuel will not exceed a specified concentration, it is preferable to control the turbine inlet temperature T1T to a first temperature. In the step of increasing the mixed combustion ratio, if it is determined based on the information that the concentration of unburned fuel is likely to exceed a specified concentration, it is preferable to control the turbine inlet temperature T1T to a second temperature higher than the first temperature.

[0078] According to the above method (4), the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration by increasing the turbine inlet temperature T1T.

[0079] (5) In some embodiments, in the method of (4) above, in step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel will not exceed a specified concentration, the increase rate Sam of the flow rate of the first fuel F1 may be set to a first increase rate Sam1 so that the turbine inlet temperature T1T becomes a first temperature. In step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel is likely to exceed a specified concentration, the increase rate Sam of the flow rate of the first fuel F1 may be set to a second increase rate Sam2 that is greater than the first increase rate Sam1 so that the turbine inlet temperature T1T becomes a second temperature.

[0080] According to the method (5) above, by increasing the rate of increase Sam of the flow rate of the first fuel F1, it is possible to prevent the concentration of unburned fuel in the combustion gas from exceeding a specified concentration.

[0081] (6) In some embodiments, in the method of (4) or (5) above, in step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel will not exceed a specified concentration, the rate of decrease Sng of the flow rate of the second fuel may be set to a first decrease rate Sng1 so that the turbine inlet temperature T1T becomes the first temperature. In step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel is likely to exceed the specified concentration, the rate of decrease Sng of the flow rate of the second fuel may be set to a second decrease rate Sng2 that is smaller than the first decrease rate Sng1 so that the turbine inlet temperature T1T becomes the second temperature.

[0082] According to the method (6) above, by reducing the rate of decrease Sng of the flow rate of the second fuel F2, it is possible to prevent the concentration of unburned fuel in the combustion gas from exceeding a specified concentration.

[0083] (7) In some embodiments, in the method of (4) above, in step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel will not exceed a specified concentration, the increase rate Sam of the flow rate of the first fuel F1 may be set to a first increase rate Sam1 and the decrease rate Sng of the flow rate of the second fuel F2 may be set to a first decrease rate Sng1 so that the turbine inlet temperature T1T becomes a first temperature while maintaining the rate of change of the mixed-combustion ratio at a first change rate. In step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel is likely to exceed the specified concentration, the increase rate Sam of the flow rate of the first fuel F1 may be set to a second increase rate Sam2 that is greater than the first increase rate Sam1 and the decrease rate Sng of the flow rate of the second fuel F2 may be set to a second decrease rate Sng2 that is smaller than the first decrease rate Sng1 so that the turbine inlet temperature T1T becomes a second temperature while maintaining the rate of change of the mixed-combustion ratio at the first change rate.

[0084] According to the method (7) above, the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration without changing the rate of change of the mixed combustion ratio.

[0085] (8) In some embodiments, in the method of (4) above, the gas turbine 2 includes a compressor (compressor 3) for supplying compressed air to the turbine 5, and an inlet guide vane 6 for adjusting the flow rate of air supplied to the compressor (compressor 3). In step S10 of increasing the mixed-fuel ratio, if it is determined based on the information above that the concentration of unburned fuel will not exceed a specified concentration, the opening degree of the inlet guide vane 6 may be set to a first opening degree so that the turbine inlet temperature T1T becomes a first temperature. In step S10 of increasing the mixed-fuel ratio, if it is determined based on the information above that the concentration of unburned fuel is likely to exceed the specified concentration, the opening degree of the inlet guide vane 6 may be set to a second opening degree smaller than the first opening degree so that the turbine inlet temperature T1T becomes a second temperature.

[0086] According to the method (8) above, by changing the opening of the inlet guide vane 6, the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration.

[0087] (9) In some embodiments, in the method of (4) above, the gas turbine 2 includes a compressor (compressor 3) for supplying compressed air to the turbine 5, a bleed line 13 for bleeding air from the compressor (compressor 3), and a control valve (bleed air amount control valve 27) for adjusting the flow rate of the compressed air flowing through the bleed air line 13. In step S10 of increasing the mixed-fuel ratio, if it is determined based on the above information that the concentration of unburned fuel will not exceed a specified concentration, the aperture of the control valve (bleed air amount control valve 27) may be set to a first aperture so that the turbine inlet temperature T1T becomes a first temperature. In step S10 of increasing the mixed-fuel ratio, if it is determined based on the above information that the concentration of unburned fuel is likely to exceed the specified concentration, the aperture of the control valve (bleed air amount control valve 27) may be set to a second aperture greater than the first aperture so that the turbine inlet temperature T1T becomes a second temperature.

[0088] According to the method (9) above, the concentration of unburned fuel in the combustion gas can be prevented from exceeding a specified concentration by changing the opening of the adjustment valve (bleed air amount adjustment valve 27).

[0089] (10) In some embodiments, in any of the methods (3) to (9) above, in step S10 of increasing the mixed combustion ratio, if it is determined based on the information that the concentration of unburned fuel will not exceed a specified concentration, the increase rate of the mixed combustion ratio may be set to a first increase rate. In step S10 of increasing the mixed combustion ratio, if it is determined based on the information that the concentration of unburned fuel is likely to exceed the specified concentration, the increase rate of the mixed combustion ratio may be set to a second increase rate that is smaller than the first increase rate.

[0090] According to the method of (10) above, by reducing the rate of increase in the mixed-combustion ratio when it is predicted that the concentration of unburned fuel of the first fuel F1 in the combustion gas will exceed a specified concentration, it is possible to reduce the increase in the concentration of unburned fuel of the first fuel F1 in the combustion gas compared to when the rate of increase in the mixed-combustion ratio is not reduced.

[0091] (11) In some embodiments, in the method of (10) above, in step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel is likely to exceed a specified concentration, the rate of increase in the mixed-combustion ratio may be set to a second rate of increase that is smaller than the first rate of increase and is equal to or greater than a predetermined lower limit.

[0092] According to the method (11) above, the mixed combustion ratio can be increased in a relatively short time while reducing the increase in the amount of unburned fuel generated.

[0093] (12) In some embodiments, in the method of (11) above, in step S10 of increasing the mixed-combustion ratio, if it is determined based on the above information that the concentration of unburned fuel is likely to exceed a specified concentration, the rate of increase in the mixed-combustion ratio may be set to a second increase rate that is smaller than the first increase rate and is a positive value equal to or greater than a predetermined lower limit value.

[0094] According to the method (12) above, the mixed combustion ratio can be increased in a relatively short time while reducing the increase in the amount of unburned fuel generated.

[0095] (13) In some embodiments, in the method of (11) above, in step S10 of increasing the mixed-combustion ratio, if it is determined based on the information that the concentration of unburned fuel is likely to exceed a specified concentration, the rate of increase in the mixed-combustion ratio may be set to a second increase rate that is a negative value that is smaller than the first increase rate and is equal to or greater than a predetermined lower limit value.

[0096] According to the method (13) above, it takes some time to increase the mixed combustion ratio, but it is possible to further reduce the increase in the amount of unburned fuel generated.

[0097] (14) In some embodiments, in any of the methods (2) to (13) above, the information may be a map showing the relationship between the turbine inlet temperature T1T, the mixed combustion ratio, and the concentration of unburned fuel.

[0098] According to the method (14) above, it becomes relatively easy to control the turbine inlet temperature T1T and the rate of change of the fuel-fuel mixture ratio.

[0099] (15) In some embodiments, in the method of (14) above, in step S10 of increasing the mixed-fuel ratio, the turbine inlet temperature T1T may be changed so as not to enter a region in which the concentration of unburned fuel is relatively high, which is preset in the map.

[0100] According to the method (15) above, the increase in the amount of unburned fuel generated can be reduced.

[0101] (16) A method for operating a gas turbine according to at least one embodiment of the present disclosure is a method for operating a gas turbine (2), and includes a step S10 of increasing a mixed-combustion ratio between a first fuel (F1) whose mixed-combustion ratio is desired to be increased and a second fuel (F2) that is different from the first fuel (F1). The gas turbine (2) includes a sensor (concentration sensor 9) for detecting unburned fuel of the first fuel (F1) in the combustion gas. In the step S10 of increasing the mixed-combustion ratio, if it is determined that the concentration has increased based on the concentration of unburned fuel of the first fuel (F1) in the combustion gas detected by the sensor (concentration sensor 9), at least one of the turbine inlet temperature (T1T) or the rate of change of the mixed-combustion ratio is changed.

[0102] According to the method (16) above, the increase in the amount of unburned fuel generated can be reduced.

[0103] (17) A gas turbine control device 100 according to at least one embodiment of the present disclosure is a control device for a gas turbine 2, and includes a fuel-mixing ratio control unit 110 configured to increase the fuel-mixing ratio between a first fuel F1 whose fuel-mixing ratio is desired to be increased and a second fuel F2 that is different from the first fuel F1. When increasing the fuel-mixing ratio, the fuel-mixing ratio control unit 110 is configured to change at least one of the turbine inlet temperature T1T or the rate of change of the fuel-mixing ratio based on information related to the relationship between the turbine inlet temperature T1T and the fuel-mixing ratio.

[0104] According to the above configuration (17), it is possible to reduce an increase in the amount of unburned fuel generated. [Explanation of symbols]

[0105] 1. Power generating equipment 2. Gas turbine 3 Compressor 4 Combustor 5 Turbine 5a Exhaust passage 6 Inlet guide vane 6a Actuator 9 Concentration sensor 20 Fuel system 21 1st fuel supply system 22 2nd fuel supply system 23 First fuel flow control valve 25 Second fuel flow control valve 27 Bleed air volume control valve 100 control device 101 processors 103 memory 110 Mixed combustion ratio control unit 111 Fuel flow rate calculation section 112 Valve control signal output unit

Claims

1. 1. A method of operating a gas turbine, comprising: increasing a mixed-combustion ratio of a first fuel whose mixed-combustion ratio is desired to be increased and a second fuel that is different from the first fuel; and in the step of increasing the fuel-mixing ratio, at least one of the turbine inlet temperature and a rate of change of the fuel-mixing ratio is changed based on information relating to a relationship between the turbine inlet temperature and the fuel-mixing ratio. How to operate a gas turbine.

2. the information is information regarding a relationship between the turbine inlet temperature, the mixed-fuel ratio, and a concentration of unburned fuel of the first fuel in the combustion gas; The method for operating a gas turbine according to claim 1 .

3. In the step of increasing the mixed combustion ratio, the turbine inlet temperature is changed based on the information so that the concentration of the unburned fuel in the combustion gas does not exceed a specified concentration. The method for operating a gas turbine according to claim 2.

4. In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel does not exceed the specified concentration, controlling the turbine inlet temperature so that the turbine inlet temperature becomes a first temperature; when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, controlling the turbine inlet temperature so that the turbine inlet temperature becomes a second temperature higher than the first temperature. The method for operating a gas turbine according to claim 3.

5. In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel does not exceed the specified concentration, setting the increase rate of the flow rate of the first fuel to a first increase rate so that the turbine inlet temperature becomes the first temperature; when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the increase rate of the flow rate of the first fuel is set to a second increase rate that is greater than the first increase rate so that the turbine inlet temperature becomes the second temperature. The method for operating a gas turbine according to claim 4.

6. In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel does not exceed the specified concentration, setting a reduction rate of the flow rate of the second fuel to a first reduction rate so that the turbine inlet temperature becomes the first temperature; when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the rate of decrease of the flow rate of the second fuel is set to a second rate of decrease that is smaller than the first rate of decrease so that the turbine inlet temperature becomes the second temperature.

6. A method for operating a gas turbine according to claim 4 or 5.

7. In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel does not exceed the specified concentration, setting the increase rate of the flow rate of the first fuel to a first increase rate and the decrease rate of the flow rate of the second fuel to a first decrease rate so that the turbine inlet temperature becomes the first temperature while maintaining the change rate of the mixed-combustion ratio at a first change rate; when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, increasing the rate of increase of the flow rate of the first fuel to a second increasing rate that is greater than the first increasing rate and decreasing the rate of decrease of the flow rate of the second fuel to a second decreasing rate that is smaller than the first decreasing rate, so that the turbine inlet temperature becomes the second temperature while maintaining the rate of change of the mixed-fuel ratio at the first changing rate; The method for operating a gas turbine according to claim 4.

8. the gas turbine includes a compressor for supplying compressed air to a turbine, and an inlet guide vane for adjusting a flow rate of air supplied to the compressor; In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel does not exceed the specified concentration, setting the opening degree of the inlet guide vane to a first opening degree so that the turbine inlet temperature becomes the first temperature; when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the opening degree of the inlet guide vanes is set to a second opening degree that is smaller than the first opening degree so that the turbine inlet temperature becomes the second temperature. The method for operating a gas turbine according to claim 4.

9. the gas turbine includes a compressor for supplying compressed air to a turbine, an extraction line for extracting air from the compressor, and a control valve for adjusting a flow rate of the compressed air flowing through the extraction line; In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel does not exceed the specified concentration, the degree of opening of the control valve is set to a first degree of opening so that the turbine inlet temperature becomes the first temperature; when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the degree of opening of the control valve is set to a second degree of opening that is greater than the first degree of opening so that the turbine inlet temperature becomes the second temperature. The method for operating a gas turbine according to claim 4.

10. In the step of increasing the mixed combustion ratio, When it is determined based on the information that the concentration of the unburned fuel does not exceed the specified concentration, the increase rate of the mixed combustion ratio is set to a first increase rate; When it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the increase rate of the mixed combustion ratio is set to a second increase rate that is smaller than the first increase rate.

5. A method for operating a gas turbine according to claim 3 or 4.

11. In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the rate of increase of the mixed combustion ratio is set to a second rate of increase that is smaller than the first rate of increase and is equal to or greater than a predetermined lower limit value. The method of operating a gas turbine according to claim 10.

12. In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the rate of increase of the mixed combustion ratio is set to a second rate of increase that is smaller than the first rate of increase and is a positive value that is equal to or greater than a predetermined lower limit value. The method of operating a gas turbine according to claim 11.

13. In the step of increasing the mixed combustion ratio, when it is determined based on the information that the concentration of the unburned fuel is likely to exceed the specified concentration, the rate of increase of the mixed combustion ratio is set to a second rate of increase that is a negative value that is smaller than the first rate of increase and is equal to or greater than a predetermined lower limit value. The method of operating a gas turbine according to claim 11.

14. the information is a map showing a relationship between the turbine inlet temperature, the mixed combustion ratio, and the concentration of the unburned fuel; The method for operating a gas turbine according to claim 2 or 3.

15. In the step of increasing the mixed combustion ratio, the turbine inlet temperature is changed so as not to enter a region, which is set in advance in the map, where the concentration of the unburned fuel is relatively high. The method of operating a gas turbine according to claim 14.

16. 1. A method of operating a gas turbine, comprising: increasing a mixed-combustion ratio of a first fuel whose mixed-combustion ratio is desired to be increased and a second fuel that is different from the first fuel; the gas turbine includes a sensor for detecting unburned fuel of the first fuel in combustion gas; and when it is determined that the concentration has increased based on the concentration of unburned fuel of the first fuel in the combustion gas detected by the sensor, in the step of increasing the mixed combustion ratio, changing at least one of a turbine inlet temperature or a rate of change of the mixed combustion ratio. How to operate a gas turbine.

17. A control device for a gas turbine, comprising: a mixed-combustion ratio control unit configured to increase a mixed-combustion ratio of a first fuel whose mixed-combustion ratio is desired to be increased and a second fuel that is different from the first fuel, the fuel-mixing ratio control unit is configured to change at least one of the turbine inlet temperature or a rate of change of the fuel-mixing ratio based on information on a relationship between the turbine inlet temperature and the fuel-mixing ratio when increasing the fuel-mixing ratio. Gas turbine control device.

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