Gas turbine operation method and gas turbine equipment capable of executing same

Abstract

This gas turbine operation method includes executing: a first fuel single firing step of supplying only a first fuel to a first nozzle of a first burner, and not supplying the first fuel and a second fuel to a second nozzle for each of a plurality of second burners; a co-firing step of supplying only the first fuel to the first nozzle, and supplying only the second fuel to the second nozzle; a second fuel single firing preparation step of supplying the second fuel only to the second nozzle, without supplying the first fuel and the second fuel to the first nozzle; and a second fuel single firing step of supplying only the second fuel to the first nozzle and the second nozzle.

Description

Gas turbine operating method and gas turbine facility capable of implementing this method

[0001] This disclosure relates to a gas turbine operating method and a gas turbine facility capable of implementing this method. This application claims priority to Japanese Patent Application No. 2023-096016, filed on June 12, 2023, the contents of which are incorporated herein by reference.

[0002] A gas turbine includes a compressor that compresses air, a combustor that burns fuel with the air compressed by the compressor to generate combustion gas, and a turbine driven by the combustion gas from the combustor. The combustor has a cylinder in which fuel can be burned and multiple burners that can inject fuel together with compressed air into the cylinder. Each of the multiple burners has an air flow path frame through which air can flow and that can inject air into the cylinder, and a nozzle that can inject fuel into the air flow path frame.

[0003] The above gas turbine may be operated using two types of fuel. Patent Document 1 (Patent Document 1) below discloses a fuel supply system capable of supplying two types of fuel to a combustor. The fuel supply system includes a first fuel line through which a first fuel can flow, a second fuel line through which a second fuel can flow, an integrated line through which the first and second fuels can flow, and branch lines branching from the integrated line and branching off for each of a plurality of nozzles. Both the first fuel line and the second fuel line are connected to one end of the integrated line. A three-way valve is provided at one end of the integrated line. This three-way valve can realize the following three configurations. In the first configuration, only the first fuel from the first fuel line is guided to the integrated line. In the second configuration, only the second fuel from the second fuel line is guided to the integrated line. In the third configuration, the first fuel from the first fuel line and the second fuel from the second fuel line are guided to the integrated line. Each branch line is connected to one of a plurality of nozzles. Each branch line is also provided with a nozzle valve.

[0004] In this fuel supply system, when the first fuel and the second fuel are supplied to the combustor simultaneously, the third configuration is adopted. That is, in this case, the first fuel from the first fuel line and the second fuel from the second fuel line are introduced into the integrated line. Therefore, in this fuel supply system, the first fuel and the second fuel are mixed in the integrated line to form a mixed fuel, and then the mixed fuel is injected from the multiple nozzles of the combustor.

[0005] Japanese Patent Application Laid-Open No. 2009-210200

[0006] When two types of fuel are used as fuel for a gas turbine, it is possible to switch from the first fuel to the second fuel while the gas turbine is in operation. Even when switching fuels during operation, stable combustion of the fuel is required in the gas turbine.

[0007] Therefore, an object of the present disclosure is to provide a technology that can stably burn fuel even during the fuel switching process.

[0008] To achieve the above object, a gas turbine operating method as one aspect according to the present disclosure is applied to the following gas turbine. The gas turbine includes a compressor capable of compressing air to generate compressed air, a combustor capable of burning fuel in the compressed air to generate combustion gas, and a turbine capable of being driven by the combustion gas. The combustor has a chamber capable of combusting fuel and a plurality of burners capable of injecting fuel together with the compressed air into the chamber. The plurality of burners include a first burner and a plurality of second burners excluding the first burner. The first burner and the plurality of second burners each have an air flow path frame through which air can flow and which can inject air into the chamber, and a nozzle capable of injecting fuel into the air flow path frame. The gas turbine operating method includes a fuel switching process of switching the fuel supplied to the combustor from a first fuel to a second fuel. The fuel switching process includes a first-fuel exclusive combustion process in which only the first fuel is supplied to a first nozzle that is the nozzle of the first burner, and neither the first fuel nor the second fuel is supplied to second nozzles that are the nozzles of each of the plurality of second burners; a mixed-fuel combustion process in which, after the first-fuel exclusive combustion process, only the first fuel is supplied to the first nozzle and only the second fuel is supplied to the second nozzle; a second-fuel exclusive combustion preparation process in which, after the mixed-fuel combustion process, neither the first fuel nor the second fuel is supplied to the first nozzle, and the second fuel is supplied only to the second nozzle; and a second-fuel exclusive combustion process in which, after the second-fuel exclusive combustion preparation process, only the second fuel is supplied to the first nozzle and the second nozzle.

[0009] In this embodiment, even if one of the two types of fuel has inferior fuel characteristics compared to the other fuel, this can be compensated for by the combustion of the other fuel, so that the fuel can be burned stably even during the fuel switching process.

[0010] To achieve the above object, one aspect of the present disclosure provides a gas turbine facility including: a compressor capable of compressing air to generate compressed air; a combustor capable of burning fuel in the compressed air to generate combustion gas; a turbine capable of being driven by the combustion gas; and a fuel supply system capable of supplying a first fuel and a second fuel to the combustor. The combustor has a cylinder capable of combusting fuel and a plurality of burners capable of injecting fuel together with compressed air into the cylinder. The plurality of burners includes a first burner and a plurality of second burners excluding the first burner. The first burner and the plurality of second burners each have an air flow path frame through which air can flow and which can inject air into the cylinder, and a nozzle which can inject fuel into the air flow path frame. The fuel supply system includes a first fuel line connected to a supply source of the first fuel and through which the first fuel can flow, a second fuel line connected to a supply source of the second fuel and through which the second fuel can flow, a first fuel valve provided in the first fuel line, a second fuel valve provided in the second fuel line, a header line through which the first fuel and the second fuel can flow, branch lines branching from the header line for each of the plurality of burners, and a gate valve provided in the header line and capable of dividing the header line into a first header section and a second header section. A first branch line, which is one of the branch lines for each of the plurality of burners, branches from the first header section. The first branch line is connected to a first nozzle, which is the nozzle of the first burner. A plurality of second branch lines, excluding the first branch line, branch from the second header section, among the branch lines for each of the plurality of burners. Each of the plurality of second branch lines is connected to a second nozzle, which is the nozzle of the plurality of second burners. The first fuel line is connected to the first header portion, and the second fuel line is connected to the second header portion.

[0011] In this aspect, the first fuel is ejected from the first nozzle, and while the first fuel is being combusted, the second fuel is ejected from the second nozzle and combusted. Therefore, in this aspect, even if one of the two types of fuel has inferior fuel characteristics to the other fuel, this can be compensated for by the combustion of the other fuel, and stable combustion of the fuels can be achieved even during the fuel switching process.

[0012] In one aspect of the present disclosure, stable combustion of fuel can be achieved even during the fuel switching process.

[0013] FIG. 1 is a schematic diagram showing a configuration of a gas turbine in an embodiment according to the present disclosure. FIG. 2 is a partial cross-sectional view of the combustor and its surroundings of the gas turbine in an embodiment according to the present disclosure. FIG. 3 is a view taken along arrow III in FIG. 2. FIG. 4 is a functional block diagram of a control device in an embodiment according to the present disclosure. FIG. 5 is an explanatory diagram showing the details of a first fuel switching process in an embodiment according to the present disclosure. FIG. 6 is an explanatory diagram showing the details of a modified example of the first fuel switching process in an embodiment according to the present disclosure. FIG. 7 is an explanatory diagram showing the details of a second fuel switching process in an embodiment according to the present disclosure. FIG. 8 is an explanatory diagram showing the details of a third fuel switching process in an embodiment according to the present disclosure. FIG. 9 is an explanatory diagram showing the details of a fourth fuel switching process in an embodiment according to the present disclosure. FIG. 10 is an explanatory diagram showing the details of a fuel switching process in a first comparative example. FIG. 11 is an explanatory diagram showing the details of a fuel switching process in a second comparative example. FIG. 12 is an explanatory diagram simply showing the details of a first fuel switching process in an embodiment according to the present disclosure.

[0014] Hereinafter, embodiments of a gas turbine operation method according to the present disclosure and a gas turbine facility capable of implementing this method will be described in detail with reference to the drawings.

[0015] Configuration of Gas Turbine Facility As shown in FIG. 1 , the gas turbine facility in this embodiment includes a gas turbine 1 , a fuel supply system 30 capable of supplying fuel to the gas turbine 1 , and a control device 50 .

[0016] The gas turbine 1 includes a compressor 10 capable of compressing air A to generate compressed air Acom, a combustor 20 capable of burning fuel in the compressed air Acom to generate combustion gas CG, and a turbine 15 capable of being driven by the combustion gas CG.

[0017] The compressor 10 has a compressor rotor 11 that rotates about a rotor axis Ar, and a compressor casing 12 that covers the compressor rotor 11. The turbine 15 has a turbine rotor 16 that rotates about the rotor axis Ar, and a turbine casing 17 that covers the turbine rotor 16. In the following description, the direction in which the rotor axis Ar extends is referred to as a rotor axial direction Da, and one of both sides of the rotor axial direction Da is referred to as an axial upstream side Dau, and the other is referred to as an axial downstream side Dad.

[0018] The compressor 10 is disposed on the axial upstream side Dau of the turbine 15. The compressor rotor 11 and the turbine rotor 16 are located on the same rotor axis Ar and are connected to each other to form a gas turbine rotor 2. To this gas turbine rotor 2, for example, a rotor of a generator GEN is connected.

[0019] The gas turbine 1 further includes an intermediate casing 3 disposed between the compressor casing 12 and the turbine casing 17. Compressed air Acom from the compressor 10 flows into the intermediate casing 3. The combustor 20 is attached to the intermediate casing 3.

[0020] A fuel supply system 30 is connected to the combustor 20. The combustor 20 is capable of burning fuel from the fuel supply system 30 in compressed air Acom from the compressor 10 to generate combustion gas CG.

[0021] As shown in Fig. 2 , the combustor 20 includes an outer casing 21, an end cover 22, an inner casing 23, an air hole plate 24, a combustion casing 25, and a plurality of burner groups 26. The outer casing 21, the inner casing 23, and the combustion casing 25 are all cylindrically shaped around a combustor axis Ac. Here, the direction in which the combustor axis Ac extends is referred to as a combustor axial direction Dc, one side of the combustor axial direction Dc is referred to as a base end side Dcb, and the other side of the combustor axial direction Dc is referred to as a tip side Dct.

[0022] An end on the tip side Dct of the external cylinder 21 is connected to the intermediate casing 3. An end on the base side Dcb of the external cylinder 21 is closed by an end cover 22. The inner cylinder 23 is disposed on the inner circumferential side of the external cylinder 21 with a gap therebetween. A flow path for the compressed air Acom that has flowed into the intermediate casing 3 is formed between the inner circumferential side of the external cylinder 21 and the outer circumferential side of the inner cylinder 23. The air hole plate 24 is disposed on the inner circumferential side of the inner cylinder 23. The air hole plate 24 is also disposed on the end cover 22 with a gap therebetween in the combustor axial direction Dc. A flow path for the compressed air Acom is formed between the end cover 22 and the air hole plate 24. This flow path is connected to a flow path between the inner circumferential side of the external cylinder 21 and the outer circumferential side of the inner cylinder 23. The air hole plate 24 is fixed to the end cover 22 via a support or the like. The inner cylinder 23 is fixed to the air hole plate 24. A plurality of air holes 24h penetrating in the combustor axial direction Dc are formed in the air hole plate 24. The combustion cylinder 25 is fixed to a tip side Dct of the inner cylinder 23. The inner peripheral side of this combustion cylinder 25 forms a combustion space in which fuel is combusted.

[0023] As shown in FIG. 3 , the multiple burner groups 26 include an inner burner group 26i and multiple outer burner groups 26o. The inner burner group 26i is arranged on the combustor axis Ac. The multiple outer burner groups 26o are arranged around the inner burner group 26i. Each of the multiple burner groups 26 includes a first burner 27a and multiple second burners 27b. The multiple second burners 27b are arranged around the first burner 27a. The first burner 27a and the multiple second burners 27b each include an air flow path frame 28 through which air can flow and which can inject air into the combustion liner 25, and a nozzle 29 disposed in the air flow path frame 28 and which can inject fuel into the air flow path frame 28. Note that, hereinafter, the nozzle 29 of the first burner 27a will be referred to as the first nozzle 29a, and the nozzle 29 of the second burner 27b will be referred to as the second nozzle 29b. Furthermore, the air flow path frame 28 of the first burner 27a is referred to as a first air flow path frame 28a, and the air flow path frame 28 of the second burner 27b is referred to as a second air flow path frame 28b. Furthermore, in Fig. 3, one burner group 26 is depicted as having one first burner 27a and six second burners 27b. However, in reality, one burner group 26 has several first burners 27a and several tens of second burners 27b. For this reason, the combustor 20 in this embodiment is referred to as a multi-cluster combustor.

[0024] The inner peripheral surface of the air flow path frame 28 of each burner 27 is formed by the inner peripheral surface of one of the plurality of air holes 24h of the air hole plate 24. Thus, each air flow path frame 28 is formed by a part of the air hole plate 24.

[0025] As shown in Fig. 2, the compressed air Acom that has flowed into the intermediate casing 3 passes through the passage between the inner periphery of the outer casing 21 and the outer periphery of the inner casing 23, and the passage between the end cover 22 and the air hole plate 24, as described above, and then flows into the air flow path frame 28 for each of the plurality of burners 27. The nozzles 29 for each of the plurality of burners 27 inject fuel into the air flow path frame 28. Air and fuel are injected from the air flow path frame 28 for each of the plurality of burners 27 into the combustion liner 25. The fuel injected into the combustion liner 25 is combusted in air that has also been injected into the combustion liner 25. The combustion gas formed by this combustion flows into the turbine 15.

[0026] The fuel supply system 30 is capable of supplying a first fuel NG and a second fuel HG to the combustor 20. In the present embodiment, the first fuel NG is natural gas, and the second fuel HG is hydrogen gas. As shown in Fig. 2 , the fuel supply system 30 includes a first fuel line 31, a second fuel line 32, a first fuel valve 33 provided in the first fuel line 31, a second fuel valve 34 provided in the second fuel line 32, a header line 36, a first gate valve 37a and a second gate valve 37b provided in the header line 36, a connecting line 35, a mixture ratio adjustment valve 35v provided in the connecting line 35, branch lines 38 branching from the header line 36 for each of the plurality of burners 27, and nozzle valves 39 provided in the branch lines 38 for each of the plurality of burners 27.

[0027] The first fuel line 31 is connected to a supply source of the first fuel NG and is a line through which the first fuel NG can flow. The second fuel line 32 is connected to a supply source of the second fuel HG and is a line through which the second fuel HG can flow.

[0028] The first gate valve 37a provided in the header line 36 can divide the header line 36 into a first header section 36a and a second header section 36b. The second gate valve 37b provided in the header line 36 can divide the second header section 36b into a first-side second header section 36bi on the first header section 36a side and a second-side second header section 36bo, which is the remaining portion of the second header section 36b. The first fuel line 31 is connected to the first header section 36a in the header line 36. The second fuel line 32 is connected to the second-side second header section 36bo in the header line 36.

[0029] A plurality of first branch lines 38a, which are some of the branch lines 38 for each of the plurality of burners 27, branch out from the first header section 36a. Each of the plurality of first branch lines 38a is connected to a first nozzle 29a, which is a nozzle 29 for each of the plurality of first burners 27a. A plurality of second branch lines 38b, which are the branch lines 38 excluding the plurality of first branch lines 38a, branch out from the second header section 36b. Each of the plurality of second branch lines 38b is connected to a second nozzle 29b, which is a nozzle 29 for each of the plurality of second burners 27b. A plurality of first-side second branch lines 38bi, which are some of the second branch lines 38b for each of the plurality of second branch lines 38b, branch out from a first-side second header section 36bi, which is part of the second header section 36b. Each of the plurality of first-side second branch lines 38bi is connected to a plurality of first-side second nozzles 29bi, which are some of the second nozzles 29b for each of the plurality of second nozzles 29b. A plurality of second-side second branch lines 38bo, which are the second branch lines 38b excluding the plurality of first-side second branch lines 38bi, branch off from the second-side second header section 36bo, which is part of the second header section 36b. Each of the plurality of second-side second branch lines 38bo is connected to a plurality of second-side second nozzles 29bo, which are the second nozzles 29b excluding the plurality of first-side second nozzles 29bi, among the plurality of second nozzles 29b.

[0030] The first-side second nozzle 29bi is the second nozzle 29b of the inner burner group 26i among the plurality of burner groups 26. The second-side second nozzle 29bo is the second nozzle 29b of the outer burner group 26o among the plurality of burner groups 26.

[0031] The connecting line 35 connects the first fuel line 31 to a position between the position where the first fuel line 31 is connected to the header line 36 and the position where the first fuel valve 33 is provided, and the second fuel line 32 to a position between the position where the second fuel line 32 is connected to the header line 36 and the position where the second fuel valve 34 is provided.

[0032] As shown in FIG. 4 , the control device 50 has a heat generation amount calculator 51, a valve control amount calculator 52, and a valve signal generator 53. The heat generation amount calculator 51 receives a required output PWr for the gas turbine 1 from the outside. The heat generation amount calculator 51 calculates the total amount of heat generated by the combustion of the fuel supplied to the combustor 20 in accordance with the required output PWr. The valve control amount calculator 52 receives a fuel switching command SS from the outside and also receives the total amount of heat generated from the heat generation amount calculator 51. The valve control amount calculator 52 calculates the control amounts of the multiple valves described above in accordance with the switching command SS and the total amount of heat generated. The valve signal generator 53 receives the control amounts of the multiple valves from the valve control amount calculator 52. The valve signal generator 53 creates a valve signal for each valve in accordance with the control amount for each of the multiple valves and sends the valve signal to the corresponding valve.

[0033] The control device 50 is capable of executing a fuel switching process in which the fuel supplied to the combustor 20 is switched from the first fuel NG to the second fuel HG. The control device 50 is capable of executing a first fuel switching process, a second fuel switching process, a third fuel switching process, and a fourth fuel switching process as the fuel switching processes. Note that, during the execution of these fuel switching processes, the gas turbine output does not change. In other words, during the execution of these fuel switching processes, the total heat value generated by the combustion of the fuel supplied to the combustor 20 does not change.

[0034] "First fuel switching process in this embodiment"

[0035] The first fuel switching process in this embodiment will be described with reference to Figure 5. This first fuel switching process is a process of switching the fuel from the first fuel (NG) to the second fuel (HG) when the gas turbine output is low. This first fuel switching process includes a first fuel exclusive combustion process S1, a dual combustion process S2, a second fuel exclusive combustion preparation process S3, and a second fuel exclusive combustion process S4. Note that for simplification, some of the first nozzles 29a and some of the second nozzles 29b are omitted from Figure 5.

[0036] In the first fuel mono-combustion step S1, the control device 50 opens the first fuel valve 33, closes the second fuel valve 34, closes the first gate valve 37a, opens the second gate valve 37b, and closes the mixture ratio control valve 35v. As a result, the second fuel HG does not flow into the header line 36, and only the first fuel NG flows into the first header section 36a in the header line 36. The first fuel NG that has flowed into the first header section 36a flows into the multiple first nozzles 29a via multiple first branch lines 38a branching from the first header section 36a, and is sprayed from the multiple first nozzles 29a. At this time, all of the nozzle valves 39 provided in the multiple first branch lines 38a are open.

[0037] As described above, in this first fuel exclusive combustion step S1, only the first fuel NG is supplied to the plurality of first nozzles 29 a, and neither the first fuel NG nor the second fuel HG is supplied to the plurality of second nozzles 29 b. Therefore, in this first fuel exclusive combustion step S1, only the first fuel NG injected from the first nozzles 29 a is combusted.

[0038] In order to realize the first-fuel-only combustion process S1, the heat generation amount calculator 51 of the control device 50 calculates the total heat generation amount generated by the combustion of the fuel supplied to the combustor 20 in order to reduce the gas turbine output. The valve control amount calculator 52 calculates the total flow rate of the first fuel NG corresponding to this total heat generation amount. Based on this total flow rate of the first fuel NG, the valve control amount calculator 52 selects nozzles 29 that supply the first fuel NG from the multiple nozzles 29 and determines the flow rate of the first fuel NG to be supplied to each nozzle 29. In this example, the valve control amount calculator 52 selects multiple first nozzles 29a from the multiple nozzles 29. The valve control amount calculator 52 then determines the open / close states of the first fuel valve 33, the second fuel valve 34, the first gate valve 37a, the second gate valve 37b, and the mixture ratio control valve 35v, and determines the valve opening degrees of each nozzle valve 39 provided in the multiple first branch lines 38a, so that the first fuel NG is supplied only to the multiple first nozzles 29a. The valve signal generator 53 generates valve signals for the plurality of valves according to the contents determined for the plurality of valves by the valve control amount calculator 52, and sends each valve signal to the corresponding valve.

[0039] After the first-fuel exclusive combustion step S1, the control device 50 executes the mixed combustion step S2. In the mixed combustion step S2, the control device 50 opens the first fuel valve 33, opens the second fuel valve 34, closes the first gate valve 37a, opens the second gate valve 37b, and closes the mixture ratio control valve 35v. Thus, during the transition from the first-fuel exclusive combustion step S1 to the mixed combustion step S2, the second fuel valve 34, among the multiple valves, changes from a closed state to an open state. As a result, the first fuel NG continues to flow into the first header section 36a in the header line 36, and the second fuel HG flows into the second header section 36b in the header line 36. The first fuel NG that has flowed into the first header section 36a flows into the multiple first nozzles 29a via the multiple first branch lines 38a branching from the first header section 36a and is sprayed from the multiple first nozzles 29a. Furthermore, the second fuel HG that has flowed into the second header portion 36b flows into the plurality of second nozzles 29b via the plurality of second branch lines 38b branching from the second header portion 36b, and is ejected from the plurality of second nozzles 29b. At this time, the number of nozzles 29 that eject the second fuel HG is greater than the number of nozzles 29 that eject the first fuel NG. In other words, the total cross-sectional area of ​​the air flow path frame 28 from which the second fuel HG is ejected is greater than the total cross-sectional area of ​​the air flow path frame 28 from which the first fuel NG is ejected.

[0040] As described above, in the mixed combustion step S2, only the first fuel NG is supplied to the first nozzles 29 a, and only the second fuel HG is supplied to the second nozzles 29 b. Therefore, in the mixed combustion step S2, the first fuel NG injected from the first nozzles 29 a is combusted, and the second fuel HG injected from the second nozzles 29 b is combusted.

[0041] The valve control amount calculator 52 of the control device 50 calculates the total flow rate of the first fuel NG and the total flow rate of the second fuel HG corresponding to the total heat generation amount previously calculated by the heat generation amount calculator 51. Because the total heat generation amount in the first fuel exclusive combustion step S1 and the total heat generation amount in the dual combustion step S2 are the same, the total flow rate of the first fuel NG in the dual combustion step S2 in which the second fuel HG is supplied to the combustor 20 is smaller than the total flow rate of the first fuel NG in the first fuel exclusive combustion step S1 in which the second fuel HG is not supplied to the combustor 20. The valve control amount calculator 52 selects, from the total flow rate of the first fuel NG, a nozzle 29 from the plurality of nozzles 29 that will supply the first fuel NG, and determines the flow rate of the first fuel NG to be supplied to each nozzle 29. Furthermore, the valve control amount calculator 52 selects, from the total flow rate of the second fuel HG, a nozzle 29 from the plurality of nozzles 29 that will supply the second fuel HG, and determines the flow rate of the second fuel HG to be supplied to each nozzle 29. Here, the valve control amount calculator 52 selects a plurality of first nozzles 29a from among the plurality of nozzles 29 as the nozzles 29 that supply the first fuel NG. The valve control amount calculator 52 also selects a plurality of second nozzles 29b from among the plurality of nozzles 29 as the nozzles 29 that supply the second fuel HG. The valve control amount calculator 52 then determines the open / close states of the first fuel valve 33, the second fuel valve 34, the first gate valve 37a, the second gate valve 37b, and the mixture ratio control valve 35v so that the first fuel NG is supplied only to the plurality of first nozzles 29a and the second fuel HG is supplied only to the plurality of second nozzles 29b. Furthermore, the valve control amount calculator 52 determines the valve apertures of the nozzle valves 39 provided in the plurality of first branch lines 38a and the nozzles 29 provided in the plurality of second branch lines 38b.

[0042] After the mixed combustion step S2, the control device 50 executes a second-fuel exclusive combustion preparation step S3. In this second-fuel exclusive combustion preparation step S3, the control device 50 closes the first fuel valve 33, opens the second fuel valve 34, closes the first gate valve 37a, opens the second gate valve 37b, and closes the mixture ratio control valve 35v. Thus, during the transition from the mixed combustion step S2 to the second-fuel exclusive combustion preparation step S3, the first fuel valve 33, among the multiple valves, changes from an open state to a closed state. As a result, the second fuel HG continues to flow into the second header section 36b in the header line 36, while the first fuel NG no longer flows into the header line 36. The second fuel HG that has flowed into the second header section 36b flows into the multiple second nozzles 29b via the multiple second branch lines 38b branching from the second header section 36b, as in the mixed combustion step S2, and is sprayed from the multiple second nozzles 29b.

[0043] As described above, in this second-fuel exclusive combustion preparation step S3, the first fuel NG and the second fuel HG are not supplied to the first nozzles 29 a, and only the second fuel HG is supplied to the second nozzles 29 b. Therefore, in this second-fuel exclusive combustion preparation step S3, only the second fuel HG ejected from the second nozzles 29 b is combusted.

[0044] The valve control amount calculator 52 of the control device 50 calculates the total flow rate of the second fuel HG corresponding to the total heat generation amount previously calculated by the heat generation amount calculator 51. Because the total heat generation amount in the mixed combustion step S2 and the total heat generation amount in the second fuel exclusive combustion preparation step S3 are the same, the total flow rate of the second fuel HG in the second fuel exclusive combustion preparation step S3, in which only the second fuel HG is supplied to the combustor 20, is greater than the total flow rate of the second fuel HG in the mixed combustion step S2, in which the first fuel NG and the second fuel HG are supplied to the combustor 20. The valve control amount calculator 52 selects, from the plurality of nozzles 29, the nozzles 29 that supply the second fuel HG, and determines the flow rate of the second fuel HG to be supplied to each nozzle 29, based on the total flow rate of the second fuel HG. Here, the valve control amount calculator 52 selects, from the plurality of nozzles 29, the plurality of second nozzles 29b as the nozzles 29 that supply the second fuel HG. The valve control amount calculator 52 determines the open / close states of the first fuel valve 33, the second fuel valve 34, the first gate valve 37a, the second gate valve 37b, and the mixture ratio adjustment valve 35v so that the second fuel HG is supplied only to the second nozzles 29b. Furthermore, the valve control amount calculator 52 determines the valve opening degree of each of the nozzles 29 provided in the second branch lines 38b.

[0045] After the second fuel exclusive combustion preparation step S3, the control device 50 executes the second fuel exclusive combustion step S4. In this second fuel exclusive combustion step S4, the control device 50 closes the first fuel valve 33, opens the second fuel valve 34, opens the first gate valve 37a, opens the second gate valve 37b, and closes the mixture ratio adjustment valve 35v. Therefore, during the process from the second fuel exclusive combustion preparation step S3 to the second fuel exclusive combustion step S4, of the multiple valves, the first gate valve 37a changes from closed to open. As a result, only the second fuel HG flows into the entire header line 36. The second fuel HG that flows into the header line 36 flows into the second nozzles 29b via a plurality of second branch lines 38b branching from a second header section 36b in the header line 36 and is sprayed from the second nozzles 29b. The second fuel HG also flows into the first nozzles 29a via a plurality of first branch lines 38a branching from a first header section 36a in the header line 36 and is sprayed from the first nozzles 29a. However, in this embodiment, the second fuel HG is not supplied to the first nozzles 29a of the inner burner group 26i among the first nozzles 29a. That is, in this embodiment, among the nozzle valves 39 provided in the first branch lines 38a, the nozzle valve 39 of the first branch line 38a connected to the first nozzles 29a of the inner burner group 26i is closed. This is because the second fuel HG should not be supplied to the first nozzles 29a of the inner burner group 26i due to restrictions on the total flow rate of the second fuel HG supplied to the combustor 20, etc. Therefore, in this second fuel mono-combustion step S4, depending on the total flow rate of the second fuel HG supplied to the combustor 20, as shown in FIG. 6, all of the nozzle valves 39 provided in the plurality of first branch lines 38a may be opened to supply the second fuel HG to all of the first nozzles 29a.

[0046] As described above, in this second fuel exclusive combustion step S4, only the second fuel HG is supplied to all of the nozzles 29 except for the first nozzles 29a of the inner burner group 26i among the plurality of nozzles 29. Therefore, in this second fuel exclusive combustion step S4, only the second fuel HG ejected from the second nozzles 29b and the second fuel HG ejected from some of the first fuel NG are combusted.

[0047] The total flow rate of the second fuel HG in the second-fuel exclusive combustion step S4 is the same as the total flow rate of the second fuel HG in the second-fuel exclusive combustion preparation step S3. The valve control amount calculator 52 selects, from the plurality of nozzles 29, nozzles 29 that supply the second fuel HG based on the total flow rate of the second fuel HG, and determines the flow rate of the second fuel HG to be supplied to each nozzle 29. Here, the valve control amount calculator 52 selects, from the plurality of nozzles 29, a plurality of second nozzles 29b and a portion of a plurality of first nozzles 29a as the nozzles 29 that supply the second fuel HG. The valve control amount calculator 52 then determines the open / close states of the first fuel valve 33, the second fuel valve 34, the first gate valve 37a, the second gate valve 37b, and the mixture ratio control valve 35v so that the second fuel HG is supplied only to the plurality of second nozzles 29b and a portion of the plurality of first nozzles 29a. Furthermore, the valve control amount calculator 52 determines the valve opening degree of each nozzle 29 provided in the plurality of branch lines 38.

[0048] "Actions and Effects of the First Fuel Switching Process in the Present Embodiment" Actions and effects of the two comparative examples and the first fuel switching process in the present embodiment will be described with reference to Figures 10 to 13. The combustors in the two comparative examples are the same as the combustor 20 in the present embodiment. On the other hand, the fuel supply systems in the three comparative examples are different from the fuel supply system 30 in the present embodiment. Furthermore, to simplify the explanation, Figures 10 to 12 depict only the first nozzles 29a and some of the second nozzles 29b in one outer burner group 26o.

[0049] (1) First Comparative Example A first comparative example will be described with reference to FIG.

[0050] The fuel supply system 30x in the first comparative example includes a first fuel line 31x through which a first fuel NG can flow, a second fuel line 32x through which a second fuel HG can flow, an integrated line 36x through which the first fuel NG and the second fuel HG can flow, and branch lines 38 branching from the integrated line 36x and branching off for each of the plurality of nozzles 29. The first fuel line 31x and the second fuel line 32x are both connected to one end of the integrated line 36x. A first fuel valve 33 is provided in the first fuel line 31x, and a second fuel valve 34 is provided in the second fuel line 32x. The branch lines 38 branching off for each of the plurality of nozzles 29 are each provided with a nozzle valve 39. Some of the branch lines 38 branching off for each of the plurality of nozzles 29 form first branch lines 38a connected to the first nozzles 29a, and the other branch lines 38 form second branch lines 38b connected to the second nozzles 29b.

[0051] In the fuel supply system 30x in the first comparative example, when the first fuel valve 33 and the second fuel valve 34 are opened, the first fuel NG that has passed through the first fuel valve 33 and the second fuel HG that has passed through the second fuel valve 34 are inevitably mixed in the integrated line 36x. For this reason, in the fuel supply system 30x in the first comparative example, when the first fuel valve 33 and the second fuel valve 34 are opened, it is not possible to supply only the first fuel NG to some of the multiple nozzles 29 and only the second fuel HG to the remaining nozzles 29.

[0052] The fuel switching process in the first comparative example includes a first-fuel exclusive combustion process S1x, a dual-fuel combustion preparation process S2x, a mixed-fuel dual-fuel combustion process S3x, and a second-fuel exclusive combustion process S4x. The gas turbine output remains unchanged during the fuel switching process in the first comparative example. In other words, the total heat value generated by the combustion of the fuel supplied to the combustor remains unchanged during these fuel switching processes.

[0053] In the first fuel exclusive combustion step S1x, the first fuel valve 33 is opened, the second fuel valve 34 is closed, the nozzle valve 39 of the first branch line 38a is opened, and the nozzle valve 39 of the second branch line 38b is closed. As a result, the second fuel HG does not flow into the integrated line 36x, and only the first fuel NG flows into the integrated line 36x. The first fuel NG that has flowed into the integrated line 36x flows only into the first nozzle 29a via the first branch line 38a.

[0054] In this first fuel exclusive combustion step S1, only the first fuel NG is supplied to the first nozzle 29 a, and neither the first fuel NG nor the second fuel HG is supplied to the second nozzles 29 b. Therefore, in this first fuel exclusive combustion step S1x, only the first fuel NG injected from the first nozzle 29 a is combusted, similar to the first fuel exclusive combustion step S1 of the first fuel switching step in this embodiment.

[0055] In the dual-fuel combustion preparation step S2x, the first fuel valve 33 is opened, the second fuel valve 34 is closed, the nozzle valve 39 of the first branch line 38a is opened, and the nozzle valve 39 of the second branch line 38b is opened. Therefore, in the process of transitioning from the first fuel exclusive combustion step S1x to the dual-fuel combustion preparation step S2x, the nozzle valve 39 of the second branch line 38b is changed from closed to open. As a result, the first fuel NG that has flowed into the integrated line 36x flows into the first nozzle 29a via the first branch line 38a and also flows into the second nozzle 29b via the second branch line 38b.

[0056] In the mixed combustion preparation step S2x, only the first fuel NG is supplied to the first nozzle 29 a and the second nozzles 29 b. Therefore, in the mixed combustion preparation step S2x, only the first fuel NG ejected from the first nozzle 29 a and the second nozzles 29 b is combusted.

[0057] In the mixed fuel combustion process S3x, the first fuel valve 33 is open, the second fuel valve 34 is open, the nozzle valve 39 of the first branch line 38a is open, and the nozzle valve 39 of the second branch line 38b is open. Therefore, during the transition from the mixed fuel combustion preparation process S2x to the mixed fuel combustion process S3x, the second fuel valve 34 changes from a closed state to an open state. As a result, the first fuel NG and the second fuel HG flow into the integrated line 36x. The first fuel NG and the second fuel HG that flow into the integrated line 36x mix together to form a mixed fuel. The mixed fuel in the integrated line 36x flows into the first nozzle 29a via the first branch line 38a and also flows into the second nozzle 29b via the second branch line 38b.

[0058] In the mixed fuel combustion process S3x, the mixed fuel is supplied to the first nozzle 29a and the plurality of second nozzles 29b. Therefore, in the mixed fuel combustion process S3x, the mixed fuel ejected from the first nozzle 29a and the plurality of second nozzles 29b is combusted.

[0059] In the second-fuel exclusive combustion step S4x, the first fuel valve 33 is closed, the second fuel valve 34 is open, the nozzle valve 39 of the first branch line 38a is open, and the nozzle valve 39 of the second branch line 38b is open. Therefore, in the process of transitioning from the mixed-fuel combustion step S3x to the second-fuel exclusive combustion step S4x, the first fuel valve 33 changes from open to closed. As a result, only the second fuel HG flows into the integrated line 36x, and the first fuel NG does not flow into it. The second fuel HG that has flowed into the integrated line 36x flows into the first nozzle 29a via the first branch line 38a and also flows into the second nozzle 29b via the second branch line 38b.

[0060] In this second-fuel exclusive combustion step S4x, only the second fuel HG is supplied to the first nozzle 29a and the plurality of second nozzles 29b. Therefore, in this second-fuel exclusive combustion step S4x, only the second fuel HG ejected from the first nozzle 29a and the plurality of second nozzles 29b is combusted, similar to the second-fuel exclusive combustion step S4 of the first fuel switching step in this embodiment.

[0061] Incidentally, natural gas, which is the first fuel NG, has a characteristic that when the fuel-air ratio is low, its combustibility is poor and the amount of unburned fuel in the combustion gas is large, compared to hydrogen gas, which is the second fuel HG. On the other hand, hydrogen gas, which is the second fuel HG, has a characteristic that when the fuel-air ratio is high, its likelihood of flashback is significantly higher, compared to natural gas, which is the first fuel NG. However, hydrogen gas does not have a worsening combustibility even when the fuel-air ratio is low, compared to natural gas. Furthermore, natural gas does not have a significantly higher likelihood of flashback even when the fuel-air ratio is high, compared to hydrogen gas.

[0062] That is, natural gas has the characteristic of poor combustibility when the fuel-air ratio is low, but the possibility of flashback is not very high even when the fuel-air ratio is high.Furthermore, hydrogen gas has the characteristic of not significantly deteriorating combustibility when the fuel-air ratio is low, but the possibility of flashback is very high when the fuel-air ratio is high.

[0063] In the first fuel switching process in the first comparative example described above, in the first fuel exclusive combustion process S1x, only the first fuel NG is injected from only the first nozzle 29a, and neither the first fuel NG nor the second fuel HG is injected from the second nozzle 29b. Also, in the dual-fuel combustion preparation process S2x, the first fuel NG is injected from the first nozzle 29a and the plurality of second nozzles 29b. That is, in both the first fuel exclusive combustion process S1 and the dual-fuel combustion preparation process S2x, only the first fuel NG is injected.

[0064] As described above, the total heat value generated by the combustion of the fuel supplied to the combustor does not change during the fuel switching process. Therefore, the flow rate of the first fuel NG supplied to the combustor in the mixed combustion preparation process S2x is the same as the flow rate of the first fuel NG supplied to the combustor in the first-fuel-exclusive combustion process S1x. Meanwhile, the number of nozzles 29 that inject the first fuel NG in the mixed combustion preparation process S2x is greater than the number of nozzles 29 that inject the first fuel NG in the first-fuel-exclusive combustion process S1x. Therefore, the fuel-air ratio for the first fuel NG in the mixed combustion preparation process S2x is lower than the fuel-air ratio for the first fuel NG in the first-fuel-exclusive combustion process S1x. As described above, natural gas, which is the first fuel NG, has poor combustibility when its fuel-air ratio is low. Therefore, the combustibility of the fuel deteriorates in the mixed combustion preparation process S2x.

[0065] As described above, when the fuel switching process in the first comparative example is performed, the combustibility of the fuel temporarily deteriorates in the process of switching from the first fuel NG to the second fuel HG.

[0066] (2) Second Comparative Example A second comparative example will be described with reference to FIG.

[0067] The fuel supply system 30z in the second comparative example includes a first fuel line 31z through which the first fuel NG can flow, a second fuel line 32z through which the second fuel HG can flow, and second branch lines 38b branching off from the second fuel line 32z for each of the plurality of second nozzles 29b. The first fuel line 31z is connected to the first nozzles 29a. The first fuel line 31z is provided with a first fuel valve 33 and a nozzle valve 39 for the first nozzle 29a. The second fuel line 32z is completely independent from the first fuel line 31z. The second fuel line 32z is provided with a second fuel valve 34. The second branch lines 38b for each of the plurality of second nozzles 29b are provided with the nozzle valves 39.

[0068] In the fuel supply system 30z in the second comparative example, the second fuel line 32z is completely independent from the first fuel line 31z, so the first fuel NG and the second fuel HG do not mix even when the first fuel valve 33 and the second fuel valve 34 are open. Furthermore, in the fuel supply system 30z in the second comparative example, the first fuel NG can flow exclusively into the first nozzle 29a, and the second fuel HG can flow exclusively into the second nozzle 29b.

[0069] The fuel switching process in the second comparative example includes a first fuel exclusive combustion process S1z, a multi-fuel combustion process S2z, and a second fuel exclusive combustion process S4z.

[0070] In the first fuel exclusive combustion step S1z, the first fuel valve 33 is opened, the nozzle valve 39 for the first nozzle 29a is opened, the second fuel valve 34 is closed, and the nozzle valve 39 of the second branch line 38b is closed. As a result, only the first fuel NG is supplied to the first nozzle 29a, and neither the first fuel NG nor the second fuel HG is supplied to the second nozzle 29b. Therefore, in this first fuel exclusive combustion step S1z, only the first fuel NG sprayed from the first nozzle 29a is combusted.

[0071] In the mixed combustion step S2z, the first fuel valve 33 is opened, the nozzle valve 39 for the first nozzle 29a is opened, the second fuel valve 34 is opened, and the nozzle valve 39 of the second branch line 38b is opened. Therefore, during the transition from the first fuel-only combustion step S1z to the mixed combustion step S2z, the second fuel valve 34 changes from a closed state to an open state, and the nozzle valve 39 of the second branch line 38b changes from a closed state to an open state. As a result, the first fuel NG is supplied only to the first nozzle 29a, and the second fuel HG is supplied only to the multiple second nozzles 29b. Therefore, in this mixed combustion step S2z, the first fuel NG sprayed from the first nozzle 29a combusts, and the second fuel HG sprayed from the multiple second nozzles 29b combusts.

[0072] In the second-fuel exclusive combustion step S3z, the first fuel valve 33 is closed, the nozzle valve 39 for the first nozzle 29a is closed, the second fuel valve 34 is open, and the nozzle valve 39 of the second branch line 38b is open. Therefore, in the process of transitioning from the dual combustion step S2z to the second-fuel exclusive combustion step S3z, the first fuel valve 33 changes from an open state to a closed state, and the nozzle valve 39 for the first nozzle 29a changes from an open state to a closed state. As a result, only the second fuel HG is supplied to the second nozzle 29b, and neither the first fuel NG nor the second fuel HG is supplied to the first nozzle 29a.

[0073] In the second comparative example, the first fuel NG cannot be supplied to the second nozzle 29b, so the first fuel NG is supplied only to the first nozzle 29a, and a first-fuel exclusive-fuel combustion step S1z is executed. Therefore, in the second comparative example, even if an attempt is made to increase the gas turbine output by exclusively burning the first fuel NG, it is not possible to obtain a gas turbine output that corresponds to the total number of nozzles 29. Also, in the second comparative example, the second fuel HG cannot be supplied to the first nozzle 29a, so the second fuel HG is supplied only to the second nozzle 29b, and a second-fuel exclusive-fuel combustion step S3z is executed. Therefore, in the second comparative example, even if an attempt is made to increase the gas turbine output by exclusively burning the second fuel HG, it is not possible to obtain a gas turbine output that corresponds to the total number of nozzles 29. In other words, in the second comparative example, even if an attempt is made to increase the gas turbine output by exclusively burning either the first fuel NG or the second fuel HG, it is not possible to obtain a gas turbine output that corresponds to the total number of nozzles 29.

[0074] (4) First Fuel Switching Process in This Embodiment The first fuel switching process in this embodiment will be briefly described again with reference to FIG.

[0075] In the first fuel combustion step S1, the first fuel valve 33 is opened, the second fuel valve 34 is closed, and the first gate valve 37a is closed. As a result, the second fuel HG does not flow into the header line 36, and only the first fuel NG flows into the first header section 36a in the header line 36. The first fuel NG that has flowed into the first header section 36a flows into the multiple first nozzles 29a via multiple first branch lines 38a branching from the first header section 36a, and is ejected from the multiple first nozzles 29a. In this first fuel combustion step S1, only the first fuel NG is supplied to the multiple first nozzles 29a, and neither the first fuel NG nor the second fuel HG is supplied to the multiple second nozzles 29b. Therefore, in this first fuel combustion step S1, only the first fuel NG ejected from the first nozzles 29a is combusted.

[0076] In the mixed combustion step S2, the first fuel valve 33 is opened, the second fuel valve 34 is opened, and the first gate valve 37a is closed. As a result, the first fuel NG continues to flow into the first header section 36a of the header line 36, while the second fuel HG flows into the second header section 36b of the header line 36. The first fuel NG that has flowed into the first header section 36a flows into the first nozzles 29a via the first branch lines 38a branching from the first header section 36a and is ejected from the first nozzles 29a. The second fuel HG that has flowed into the second header section 36b flows into the second nozzles 29b via the second branch lines 38b branching from the second header section 36b and is ejected from the second nozzles 29b. In this mixed combustion step S2, only the first fuel NG is supplied to the first nozzles 29a, and only the second fuel HG is supplied to the second nozzles 29b. Therefore, in the mixed combustion step S2, the first fuel NG injected from the first nozzles 29a combusts, and the second fuel HG injected from the second nozzles 29b combusts. At this time, as described above, the number of nozzles 29 that eject the second fuel HG is greater than the number of nozzles 29 that eject the first fuel NG. In other words, the total cross-sectional area of ​​the air flow path frame 28 from which the second fuel HG is injected is greater than the total cross-sectional area of ​​the air flow path frame 28 from which the first fuel NG is injected.

[0077] As described above, since the total heat generation amount in the first fuel exclusive combustion step S1 and the total heat generation amount in the mixed combustion step S2 are the same, the total flow rate of the first fuel NG in the mixed combustion step S2, in which the second fuel HG is supplied to the combustor 20, is smaller than the total flow rate of the first fuel NG in the first fuel exclusive combustion step S1, in which the second fuel HG is not supplied to the combustor 20. Therefore, the fuel-air ratio for the first fuel NG in the mixed combustion step S2 is lower than the fuel-air ratio for the first fuel NG in the first fuel exclusive combustion step S1. As described above, natural gas, which is the first fuel NG, has poor combustibility when the fuel-air ratio is low. Therefore, if only the first fuel NG is combusted in this step, the combustibility of the fuel in this step will deteriorate. However, in this mixed combustion step S2, while natural gas, which is the first fuel NG ejected from the first nozzle 29a, is combusting, hydrogen gas, which is the second fuel HG ejected from the second nozzle 29b, is also combusting. Therefore, the combustion of the hydrogen gas as the second fuel HG ejected from the second nozzle 29b complements the combustibility of the natural gas as the first fuel NG, and deterioration of the combustibility of the fuel can be suppressed.

[0078] In the second-fuel exclusive combustion preparation step S3, the first fuel valve 33 is closed, the second fuel valve 34 is open, and the first gate valve 37a is closed. As a result, the second fuel HG continues to flow into the second header section 36b in the header line 36, while the first fuel NG stops flowing into the header line 36. The second fuel HG that has flowed into the second header section 36b flows into the multiple second nozzles 29b via the multiple second branch lines 38b branching from the second header section 36b, as in the dual combustion step S2, and is ejected from the multiple second nozzles 29b. Therefore, in this second-fuel exclusive combustion preparation step S3, only the second fuel HG ejected from the second nozzles 29b is combusted.

[0079] In the second fuel exclusive combustion step S4, the first fuel valve 33 is closed, the second fuel valve 34 is open, and the first gate valve 37a is open. As a result, only the second fuel HG flows into the entire header line 36. The second fuel HG that has flowed into the header line 36 flows into the plurality of second nozzles 29b via the plurality of second branch lines 38b branching from the second header section 36b in the header line 36 and is ejected from the plurality of second nozzles 29b, and also flows into the plurality of first nozzles 29a via the plurality of first branch lines 38a branching from the first header section 36a in the header line 36 and is ejected from the plurality of first nozzles 29a. Therefore, in this second fuel exclusive combustion step S4, only the second fuel HG ejected from the second nozzles 29b and the plurality of first nozzles 29a is combusted.

[0080] As described above, in this embodiment, even if the fuel-air ratio for natural gas, which is the first fuel NG, becomes low during the fuel switching process, the second fuel HG also burns while this first fuel NG is burning, so the combustibility of natural gas, which is the first fuel NG, is compensated for, and deterioration of the combustibility of the fuel can be suppressed.

[0081] "Second fuel switching process in this embodiment" The second fuel switching process in this embodiment will be described with reference to Figure 7. Like the first fuel switching process, this second fuel switching process is a process of switching the fuel from the first fuel (NG) to the second fuel (HG) when the gas turbine output is low. However, the gas turbine output during this second fuel switching process is slightly higher than the gas turbine output during the first fuel switching process. Like the first fuel switching process, this second fuel switching process also includes a first-fuel exclusive combustion process S1a, a dual-fuel combustion process S2a, a second-fuel exclusive combustion preparation process S3a, and a second-fuel exclusive combustion process S4a. Note that, for the sake of simplicity, some of the first nozzles 29a and some of the second nozzles 29b are omitted from Figure 7 as well.

[0082] In the first-fuel exclusive combustion step S1a, the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is opened, the second gate valve 37b is closed, and the mixture ratio control valve 35v is closed. In the first-fuel exclusive combustion step S1 of the first fuel switching step, the first gate valve 37a is closed and the second gate valve 37b is open, but in this first-fuel exclusive combustion step S1a, the first gate valve 37a is opened and the second gate valve 37b is closed. As a result, the second fuel HG does not flow into the header line 36, and only the first fuel NG flows into the first header section 36a and the first-side second header section 36bi in the header line 36. The first fuel NG that flows into the first header section 36a flows into the multiple first nozzles 29a via the multiple first branch lines 38a branching from the first header section 36a and is sprayed from the multiple first nozzles 29a. In addition, the first fuel NG that flows into the first side second header section 36bi flows into the first side second nozzle 29bi, which is the second nozzle 29b of the inner burner group 26i among the second nozzles 29b, via multiple first side second branch lines 38bi branching off from the first side second header section 36bi.

[0083] As described above, in this first-fuel exclusive combustion process S1a, only the first fuel NG is supplied to the plurality of first nozzles 29a and the first-side second nozzles 29bi, and the first fuel NG and the second fuel HG are not supplied to the plurality of second-side second nozzles 29bo. Therefore, in this first-fuel exclusive combustion process S1a, only the first fuel NG sprayed from the first nozzles 29a and the first-side second nozzles 29bi is combusted.

[0084] In the mixed combustion step S2a, similar to the mixed combustion step S2 of the first fuel switching step, the first fuel valve 33 is opened, the second fuel valve 34 is opened, the first gate valve 37a is closed, the second gate valve 37b is open, and the mixture ratio control valve 35v is closed. As a result, the first fuel NG continues to flow into the first header section 36a of the header line 36, and the second fuel HG flows into the second header section 36b of the header line 36. The first fuel NG that has flowed into the first header section 36a flows into the multiple first nozzles 29a via the multiple first branch lines 38a branching from the first header section 36a and is sprayed from the multiple first nozzles 29a. The second fuel HG that has flowed into the second header section 36b flows into the multiple second nozzles 29b via the multiple second branch lines 38b branching from the second header section 36b and is sprayed from the multiple second nozzles 29b. At this time, the number of nozzles 29 that eject the second fuel HG is greater than the number of nozzles 29 that eject the first fuel NG. In other words, the total cross-sectional area of ​​the air flow path frame 28 from which the second fuel HG is ejected is greater than the total cross-sectional area of ​​the air flow path frame 28 from which the first fuel NG is ejected.

[0085] As described above, in this mixed combustion step S2a, only the first fuel NG is supplied to the plurality of first nozzles 29a, and only the second fuel HG is supplied to the plurality of second nozzles 29b. Therefore, in this mixed combustion step S2a, the first fuel NG sprayed from the first nozzles 29a combusts, and the second fuel HG sprayed from the second nozzles 29b combusts.

[0086] In the second-fuel exclusive combustion preparation step S3a, similar to the second-fuel exclusive combustion preparation step S3 of the first fuel switching step, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is closed, the second gate valve 37b is open, and the mixture ratio control valve 35v is closed. As a result, the second fuel HG continues to flow into the second header section 36b in the header line 36, while the first fuel NG no longer flows into the header line 36. The second fuel HG that has flowed into the second header section 36b flows into the multiple second nozzles 29b via the multiple second branch lines 38b branching from the second header section 36b, similar to the dual-fuel combustion step S2a, and is sprayed from the multiple second nozzles 29b.

[0087] As described above, in this second-fuel exclusive combustion preparation step S3a, the first fuel NG and the second fuel HG are not supplied to the plurality of first nozzles 29a, and only the second fuel HG is supplied to the plurality of second nozzles 29b. Therefore, in this second-fuel exclusive combustion preparation step S3a, only the second fuel HG ejected from the second nozzles 29b is combusted.

[0088] In the second fuel exclusive combustion step S4a, similar to the second fuel exclusive combustion step S4 of the first fuel switching step, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, the second gate valve 37b is open, and the mixture ratio adjustment valve 35v is closed. As a result, only the second fuel HG flows into the entire header line 36. The second fuel HG that has flowed into the header line 36 flows into the plurality of second nozzles 29b via the plurality of second branch lines 38b branching off from the second header section 36b in the header line 36 and is sprayed from the plurality of second nozzles 29b, and also flows into the plurality of first nozzles 29a via the plurality of first branch lines 38a branching off from the first header section 36a in the header line 36 and is sprayed from the plurality of first nozzles 29a. However, in this second fuel exclusive combustion step S4a, as in the second fuel exclusive combustion step S4 of the first fuel switching step, the second fuel HG is not supplied to the first nozzles 29a of the inner burner group 26i among the multiple first nozzles 29a, depending on the total flow rate of the second fuel HG supplied to the combustor 20, etc. However, in this second fuel exclusive combustion step S4a, depending on the total flow rate of the second fuel HG supplied to the combustor 20, all of the nozzle valves 39 provided in the multiple first branch lines 38a may be opened to supply the second fuel HG to all of the first nozzles 29a, as described with reference to Fig. 6 .

[0089] As described above, in this second fuel exclusive combustion step S4a, only the second fuel HG is supplied to all of the nozzles 29, except for the first nozzles 29a of the inner burner group 26i, among the plurality of nozzles 29. Therefore, in this second fuel exclusive combustion step S4a, only the second fuel HG ejected from the second nozzles 29b and the second fuel HG ejected from some of the first nozzles 29a are combusted.

[0090] Like the fuel-air ratio for the first fuel NG in the mixed combustion step S2a of the second fuel switching step, the fuel-air ratio for the first fuel NG in the mixed combustion step S2 of the first fuel switching step is also lower than the fuel-air ratio for the first fuel NG in the first fuel-only combustion step S1a. However, even in this mixed combustion step S2a, while natural gas, which is the first fuel NG ejected from the first nozzle 29a, is burning, hydrogen gas, which is the second fuel HG ejected from the second nozzle 29b, is also burning. Therefore, the combustion of hydrogen gas, which is the second fuel HG ejected from the second nozzle 29b, compensates for the combustibility of natural gas, which is the first fuel NG, and deterioration of the fuel combustibility can be suppressed.

[0091] Therefore, in the second fuel switching process in this embodiment, as in the first fuel switching process, it is possible to suppress deterioration in the combustibility of the fuel during the fuel switching process.

[0092] Furthermore, the fuel supply system 30 of this embodiment has a first gate valve 37a and a second gate valve 37b as valves that separate the header line 36, making it possible to change the position at which the header line 36 is separated into two. This makes it possible to change the number of nozzles 29 that eject the first fuel NG in the first fuel exclusive combustion step S1a of the second fuel switching step and the number of nozzles 29 that eject the first fuel NG in the first fuel exclusive combustion step S1 of the first fuel switching step. This means that this embodiment can flexibly respond to output changes in the low output range when the first fuel NG is exclusively burned.

[0093] "Third fuel switching process in this embodiment" The third fuel switching process in this embodiment will be described with reference to Figure 8. Like the second fuel switching process, this second fuel switching process is a process of switching the fuel from the first fuel NG to the second fuel HG when the gas turbine output is low. Like the first fuel switching process and the second fuel switching process, this third fuel switching process also includes a first fuel exclusive combustion process S1b, a dual combustion process S2b, a second fuel exclusive combustion preparation process S3b, and a second fuel exclusive combustion process S4b. Note that, for the sake of simplicity, Figure 8 also omits some of the first nozzles 29a and some of the second nozzles 29b.

[0094] In the first fuel exclusive combustion step S1b, similar to the first fuel exclusive combustion step S1a of the second fuel switching step, the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is opened, the second gate valve 37b is closed, and the mixture ratio adjustment valve 35v is closed. As a result, the second fuel HG does not flow into the header line 36, and only the first fuel NG flows into the first header section 36a and the first-side second header section 36bi in the header line 36. The first fuel NG that has flowed into the first header section 36a flows into the multiple first nozzles 29a via the multiple first branch lines 38a branching from the first header section 36a, and is sprayed from the multiple first nozzles 29a. Furthermore, the first fuel NG that has flowed into the first-side second header section 36bi flows into the first-side second nozzles 29bi, which are the second nozzles 29b of the inner burner group 26i, among the second nozzles 29b, via a plurality of first-side second branch lines 38bi branching off from the first-side second header section 36bi. Therefore, in this first fuel exclusive combustion step S1b, only the first fuel NG ejected from the first nozzles 29a and the first-side second nozzles 29bi is combusted.

[0095] In the mixed combustion step S2b, the first fuel valve 33 is open, the second fuel valve 34 is open, the first gate valve 37a is open, the second gate valve 37b is closed, and the mixture ratio control valve 35v is closed. In the mixed combustion step S2 of the first fuel switching step and the mixed combustion step S2a of the second fuel switching step, the first gate valve 37a is closed and the second gate valve 37b is open, but in this mixed combustion step S2b, the first gate valve 37a is open and the second gate valve 37b is closed. As a result, the first fuel NG continues to flow into the first header section 36a and the first-side second header section 36bi in the header line 36. The first fuel NG that has flowed into the first header section 36a flows into the multiple first nozzles 29a via the multiple first branch lines 38a branching from the first header section 36a and is sprayed from the multiple first nozzles 29a. The first fuel NG that has flowed into the first-side second header section 36bi flows into the first-side second nozzles 29bi, which are the second nozzles 29b of the inner burner group 26i, among the second nozzles 29b, via a plurality of first-side second branch lines 38bi branching from the first-side second header section 36bi. The second fuel HG flows into the second-side second header section 36bo in the header line 36. The second fuel HG that has flowed into the second-side second header section 36bo flows into the second-side second nozzles 29bo, which are the second nozzles 29b of the outer burner group 26o, among the second nozzles 29b, via a plurality of second-side second branch lines 38bo branching from the second-side second header section 36bo. In this mixed combustion step S2b, the first fuel NG injected from the plurality of first nozzles 29a and the first-side second nozzles 29bi combusts, and the second fuel HG injected from the plurality of second-side second nozzles 29bo combusts. At this time, the number of nozzles 29 that eject the second fuel HG is greater than the number of nozzles 29 that eject the first fuel NG. In other words, the total cross-sectional area of ​​the air flow path frame 28 from which the second fuel HG is ejected is greater than the total cross-sectional area of ​​the air flow path frame 28 from which the first fuel NG is ejected.

[0096] In the second-fuel exclusive combustion preparation step S3b, similar to the second-fuel exclusive combustion preparation step S3 of the first fuel switching step and the second-fuel exclusive combustion preparation step S3a of the second fuel switching step, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is closed, the second gate valve 37b is open, and the mixture ratio control valve 35v is closed. As a result, the second fuel HG flows into the entire second header section 36b of the header line 36, and the first fuel NG no longer flows into the header line 36. The second fuel HG that has flowed into the second header section 36b flows into the multiple second nozzles 29b via the multiple second branch lines 38b branching from the second header section 36b and is sprayed from the multiple second nozzles 29b. In this second-fuel exclusive combustion preparation step S3b, neither the first fuel NG nor the second fuel HG is supplied to the multiple first nozzles 29a, and only the second fuel HG is supplied to the multiple second nozzles 29b. Therefore, in this second fuel exclusive combustion preparation step S3b, only the second fuel HG injected from the second nozzle 29b is combusted.

[0097] In the second-fuel exclusive combustion step S4b, similarly to the second-fuel exclusive combustion step S4 of the first fuel switching step and the second-fuel exclusive combustion step S4a of the second fuel switching step, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, the second gate valve 37b is open, and the mixture ratio adjustment valve 35v is closed. As a result, only the second fuel HG flows into the entire header line 36. The second fuel HG that has flowed into the header line 36 flows into the plurality of second nozzles 29b via the plurality of second branch lines 38b branching off from the second header section 36b in the header line 36 and is sprayed from the plurality of second nozzles 29b, and also flows into the plurality of first nozzles 29a via the plurality of first branch lines 38a branching off from the first header section 36a in the header line 36 and is sprayed from the plurality of first nozzles 29a. However, in this second-fuel exclusive combustion step S4b, similarly to the second-fuel exclusive combustion step S4 of the first fuel switching step and the second-fuel exclusive combustion step S4a of the second fuel switching step, the second fuel HG is not supplied to the first nozzles 29a of the inner burner group 26i among the multiple first nozzles 29a, depending on the total flow rate of the second fuel HG supplied to the combustor 20, etc. In this second-fuel exclusive combustion step S4b, too, only the second fuel HG ejected from the second nozzles 29b and the second fuel HG ejected from some of the first nozzles 29a combusts. However, in this second-fuel exclusive combustion step S4b, depending on the total flow rate of the second fuel HG supplied to the combustor 20, as described with reference to FIG. 6 , all of the nozzle valves 39 provided in the multiple first branch lines 38a may be opened to supply the second fuel HG to all of the first nozzles 29a.

[0098] The fuel-air ratio for the first fuel NG in the mixed combustion step S2b of the third fuel switching step is also lower than the fuel-air ratio for the first fuel NG in the first-fuel-only combustion step S1b, similar to the fuel-air ratio for the first fuel NG in the mixed combustion step S2 of the first fuel switching step and the mixed combustion step S2a of the second fuel switching step. However, even in this mixed combustion step S2b, while natural gas, which is the first fuel NG ejected from the first nozzle 29a, is burning, hydrogen gas, which is the second fuel HG ejected from the second nozzle 29b, is also burning. Therefore, the combustion of hydrogen gas, which is the second fuel HG ejected from the second nozzle 29b, compensates for the combustibility of natural gas, which is the first fuel NG, and deterioration of the fuel combustibility can be suppressed.

[0099] Therefore, in the third fuel switching process in this embodiment, as in the first fuel switching process, it is possible to suppress deterioration in the combustibility of the fuel during the fuel switching process.

[0100] Furthermore, the fuel supply system 30 of this embodiment has the first gate valve 37a and the second gate valve 37b as valves that separate the header line 36, making it possible to change the position at which the header line 36 is separated into two. Therefore, the number of nozzles 29 that eject the first fuel NG in the mixed combustion step S2b of the third fuel switching step can be changed relative to the number of nozzles 29 that eject the first fuel NG in the mixed combustion step S2b of the second fuel switching step. Therefore, in this embodiment, it is possible to change the amount of influence of the combustion of the second fuel HG on the combustibility of the first fuel NG in the mixed combustion step S2b.

[0101] "Fourth fuel switching process in this embodiment" The fourth fuel switching process in this embodiment will be described with reference to Figure 9. This fourth fuel switching process is a process of switching the fuel from the first fuel (NG) to the second fuel (HG) when the gas turbine output is high. This fourth fuel switching process includes a first fuel exclusive combustion process S1c, a mixed fuel combustion process S2c, and a second fuel exclusive combustion process S4c. Note that, for simplification, Figure 9 also omits some of the first nozzles 29a and some of the second nozzles 29b. Here, high output is, for example, 50% or more of the rated output of the gas turbine. However, this percentage varies depending on the gas turbine. In other words, for a certain gas turbine, high output may be, for example, 75% or more of the rated output of the gas turbine.

[0102] In the first fuel mono-combustion step S1c, the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is opened, the second gate valve 37b is opened, and the mixture ratio control valve 35v is closed. As a result, the second fuel HG does not flow into the header line 36, and only the first fuel NG flows into the header line 36. The first fuel NG that flows into the first header section 36a in the header line 36 flows into the multiple first nozzles 29a via multiple first branch lines 38a branching from the first header section 36a, and is sprayed from the multiple first nozzles 29a. The first fuel NG that flows into the second header section 36b in the header line 36 flows into the second nozzles 29b via multiple second branch lines 38b branching from the second header section 36b.

[0103] As described above, in this first fuel exclusive combustion process S1c, only the first fuel NG is supplied to all of the nozzles 29. Therefore, in this first fuel exclusive combustion process S1c, only the first fuel NG ejected from all of the nozzles 29 is combusted.

[0104] In the mixed fuel combustion step S2c, the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is opened, the second gate valve 37b is opened, and the mixture ratio control valve 35v is opened. If the supply pressure of the second fuel HG from the second fuel supply source is higher than the supply pressure of the first fuel NG from the first fuel supply source, the second fuel HG flows from the second fuel line 32 through the connecting line 35 and the mixture ratio control valve 35v into the first fuel line 31, where it mixes with the first fuel NG to form a mixed fuel. This mixed fuel flows into the header line 36. The mixed fuel that flows into the first header section 36a in the header line 36 flows into the multiple first nozzles 29a through multiple first branch lines 38a branching from the first header section 36a, and is sprayed from the multiple first nozzles 29a. The mixed fuel that has flowed into the second header section 36b of the header line 36 flows into the second nozzle 29b via a plurality of second branch lines 38b branching from the second header section 36b.

[0105] As described above, in this mixed fuel combustion step S2c, the mixed fuel is supplied to all of the nozzles 29. Therefore, in this mixed fuel combustion step S2c, the mixed fuel ejected from all of the nozzles 29 is combusted.

[0106] As described above, when the supply pressure of the second fuel HG from the second fuel supply source is higher than the supply pressure of the first fuel NG from the first fuel supply source, a portion of the second fuel HG flows from the second fuel line 32 through the connecting line 35 and the mixing ratio control valve 35v into the first fuel line 31, where it mixes with the first fuel NG to form a mixed fuel. However, there is a possibility that another portion of the second fuel HG flows directly from the second fuel line 32 into the header line 36. Therefore, it is preferable to provide the downstream second fuel valve 34a in the second fuel line 32 at a position between the connecting position with the connecting line 35 and the connecting position with the header line 36. In the mixed fuel combustion step S2c, the downstream second fuel valve 34a is closed to prevent a portion of the second fuel HG from flowing directly from the second fuel line 32 into the header line 36.

[0107] In the second fuel mono-combustion step S4c, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, the second gate valve 37b is open, and the mixture ratio control valve 35v is closed. As a result, the first fuel NG does not flow into the header line 36, and only the second fuel HG flows into the header line 36. The second fuel HG that flows into the first header section 36a in the header line 36 flows into the multiple first nozzles 29a via the multiple first branch lines 38a branching from the first header section 36a, and is sprayed from the multiple first nozzles 29a. The second fuel HG that flows into the second header section 36b in the header line 36 flows into the second nozzles 29b via the multiple second branch lines 38b branching from the second header section 36b.

[0108] As described above, in this second fuel exclusive combustion process S4c, only the second fuel HG is supplied to all of the nozzles 29. Therefore, in this second fuel exclusive combustion process S4c, only the first fuel NG injected from all of the nozzles 29 is combusted.

[0109] In this embodiment, the first fuel NG can be supplied to all of the nozzles 29, and the second fuel HG can be supplied to all of the nozzles 29. Therefore, in this embodiment, unlike the second comparative example described above, a gas turbine output commensurate with the total number of nozzles 29 can be obtained by burning only one of the first fuel NG and the second fuel HG.

[0110] "Summary of Effects of the Present Embodiment"

[0111] In the embodiment, even if one of the two types of fuel has inferior fuel characteristics compared to the other fuel, this can be compensated for by the combustion of the other fuel, so that the fuel can be burned stably even during the fuel switching process.

[0112] In this embodiment, a gas turbine output corresponding to the total number of nozzles 29 can be obtained by burning only one of the first fuel NG and the second fuel HG.

[0113] In this embodiment, the fuel switching process can be performed in the form of a first fuel switching process, a second fuel switching process, a third fuel switching process, and a fourth fuel switching process, so that the manner of fuel switching can be changed as appropriate.

[0114] Furthermore, the fuel supply system 30 of this embodiment has the first gate valve 37a and the second gate valve 37b as valves that separate the header line 36, making it possible to change the position at which the header line 36 is separated into two. Therefore, the number of nozzles 29 that eject the first fuel NG and the number of nozzles 29 that eject the second fuel HG can be changed as needed.

[0115] "Modifications" In the above embodiment, the first fuel NG is natural gas, and the second fuel HG is hydrogen gas. However, the combination of the two fuels is not limited to the combination in this embodiment. For example, one of the two fuels may be natural gas, and the other may be any one of ammonia gas, COG (Coke Oven Gas), propane gas, coal gasification gas, etc.

[0116] Furthermore, the present disclosure is not limited to the embodiment and modifications described above, and various additions, modifications, substitutions, partial deletions, etc. are possible within the scope of the conceptual idea and spirit of the present invention derived from the content defined in the claims and their equivalents.

[0117] [Additional Note] The gas turbine operating method in the above embodiment can be understood, for example, as follows.

[0118] (1) The gas turbine operating method according to the first aspect is applied to the following gas turbine. The gas turbine includes a compressor 10 capable of compressing air to generate compressed air Acom, a combustor 20 capable of burning fuel in the compressed air Acom to generate combustion gas, and a turbine 15 capable of being driven by the combustion gas. The combustor 20 includes a cylinder 25 capable of combusting fuel and a plurality of burners 27 capable of injecting fuel into the cylinder 25 together with the compressed air Acom. The plurality of burners 27 includes a first burner 27a and a plurality of second burners 27b excluding the first burner 27a. The first burner 27a and the plurality of second burners 27b each include an air flow path frame 28 through which air can flow and which can inject air into the cylinder 25, and a nozzle 29 capable of injecting fuel into the air flow path frame 28. In this method for operating the gas turbine 1, a fuel switching step is executed in which the fuel supplied to the combustor 20 is switched from the first fuel NG to the second fuel HG. The fuel switching process includes a first-fuel exclusive combustion process S1 in which only the first fuel NG is supplied to a first nozzle 29a, which is the nozzle 29 of the first burner 27a, and neither the first fuel NG nor the second fuel HG is supplied to a second nozzle 29b, which is the nozzle 29 of each of the plurality of second burners 27b; a mixed-fuel combustion process S2 in which, after the first-fuel exclusive combustion process S1, only the first fuel NG is supplied to the first nozzle 29a, and only the second fuel HG is supplied to the second nozzle 29b; a second-fuel exclusive combustion preparation process S3 in which, after the mixed-fuel combustion process S2, neither the first fuel NG nor the second fuel HG is supplied to the first nozzle 29a, and only the second fuel HG is supplied to the second nozzle 29b; and a second-fuel exclusive combustion process S4 in which, after the second-fuel exclusive combustion preparation process S3, only the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b.

[0119] In this embodiment, even if one of the two types of fuel has inferior fuel characteristics compared to the other fuel, this can be compensated for by the combustion of the other fuel, so that the fuel can be burned stably even during the fuel switching process.

[0120] (2) A second aspect of the gas turbine operating method is the method for operating the gas turbine 1 according to the first aspect, in which a second fuel switching process is executed in addition to the first fuel switching process, which is the fuel switching process. The second fuel switching process includes a first fuel exclusive combustion process S1a in which only the first fuel NG is supplied to the first-side second nozzles 29bi and the first nozzles 29a, which are some of the second nozzles 29b of the second nozzles 29b of each of the second burners 27b, and the first fuel NG and the second fuel HG are not supplied to the second-side second nozzles 29bo, excluding the first-side second nozzles 29bi, of the second nozzles 29b of each of the second burners 27b; and a second fuel exclusive combustion process S1b in which, after the first fuel exclusive combustion process S1a, the first nozzles 29b are supplied to the first nozzles 29b. a mixed combustion process S2a in which only the first fuel NG is supplied to the first nozzle 29a and only the second fuel HG is supplied to the second nozzle 29b; a second fuel exclusive combustion preparation process S3a in which, after the mixed combustion process S2a, the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a and the second-side second nozzle 29bo is supplied with the second fuel HG only to the second-side second nozzle 29bo; and a second fuel exclusive combustion process S4a in which, after the second fuel exclusive combustion preparation process S3a, only the second fuel HG is supplied to the first nozzle 29a and the second-side second nozzle 29bo.

[0121] In this embodiment, in addition to the first fuel switching process, a second fuel switching process can also be performed, and the mode of fuel switching can be changed as appropriate.

[0122] (3) In a third aspect, the gas turbine operating method is the method for operating the gas turbine 1 in the first or second aspect, and in addition to the first fuel switching process, which is the fuel switching process, a third fuel switching process is executed. The third fuel switching process includes a first-fuel exclusive combustion process S1b in which only the first fuel NG is supplied to the first-side second nozzles 29bi and the first nozzles 29a, which are some of the second nozzles 29b of the second nozzles 29b of each of the second burners 27b, and the first fuel NG and the second fuel HG are not supplied to the second-side second nozzles 29bo, excluding the first-side second nozzles 29bi, of the second nozzles 29b of each of the second burners 27b; and a first-fuel exclusive combustion process S1b in which, after the first-fuel exclusive combustion process S1b, the first nozzles 29a and the first-side second nozzles 29bi are supplied with the first fuel NG and the second fuel HG. a second fuel exclusive combustion preparation process S3b, after the second fuel exclusive combustion process S2b, in which neither the first fuel NG nor the second fuel HG is supplied to the first nozzle 29a, and the second fuel HG is supplied only to the second-side second nozzle 29bo; and a second fuel exclusive combustion process S4b, after the second fuel exclusive combustion preparation process S3b, in which only the second fuel HG is supplied to the first nozzle 29a and the second-side second nozzle 29bo.

[0123] In this embodiment, in addition to the first fuel switching process, a third fuel switching process can also be performed, and the mode of fuel switching can be changed as appropriate.

[0124] (4) A fourth aspect of the gas turbine operating method is the method for operating a gas turbine 1 according to any one of the first to third aspects, further comprising the step of executing a fourth fuel switching step in addition to the first fuel switching step, which is the fuel switching step. The fourth fuel switching step includes a first-fuel exclusive combustion step S1c of supplying only the first fuel NG to the first nozzle 29a and the second nozzle 29b, a mixed-fuel combustion step S2c of supplying a mixed fuel of the first fuel NG and the second fuel HG to the first nozzle 29a and the second nozzle 29b after the first-fuel exclusive combustion step S1c, and a second-fuel exclusive combustion step S4c of supplying only the second fuel HG to the first nozzle 29a and the second nozzle 29b after the mixed-fuel combustion step S2c.

[0125] In this embodiment, in addition to the first fuel switching process, a fourth fuel switching process can also be performed, and the manner of fuel switching can be changed as appropriate.

[0126] (5) A fifth aspect of the gas turbine operating method is the method for operating a gas turbine 1 according to any one of the first to fourth aspects, wherein the combustor 20 has a plurality of burner groups 26. Each of the plurality of burner groups 26 has the first nozzle 29 a and the second nozzle 29 b arranged around the first nozzle 29 a. The first fuel NG is natural gas, and the second fuel HG is hydrogen gas.

[0127] (6) A sixth aspect of the present invention relates to a method for operating a gas turbine 1 according to the second or third aspect, wherein the combustor 20 has a plurality of burner groups 26. The plurality of burner groups 26 include an inner burner group 26i and a plurality of outer burner groups 26o arranged around the inner burner group 26i. Each of the plurality of burner groups 26 has the first nozzle 29a and the second nozzle 29b arranged around the first nozzle 29a. The first-side second nozzle 29bi is the second nozzle 29b included in the inner burner group 26i. The plurality of second-side second nozzles 29bo are the second nozzles 29b included in each of the plurality of outer burner groups 26o. The first fuel NG is natural gas, and the second fuel HG is hydrogen gas.

[0128] The gas turbine facility in the above embodiment can be understood, for example, as follows.

[0129] (7) A gas turbine facility according to a seventh aspect includes a compressor 10 capable of compressing air to generate compressed air Acom, a combustor 20 capable of burning fuel in the compressed air Acom to generate combustion gas, a turbine 15 capable of being driven by the combustion gas, and a fuel supply system 30 capable of supplying a first fuel NG and a second fuel HG to the combustor 20. The combustor 20 has a cylinder 25 capable of combusting fuel and a plurality of burners 27 capable of injecting fuel together with the compressed air Acom into the cylinder 25. The plurality of burners 27 includes a first burner 27a and a plurality of second burners 27b excluding the first burner 27a. The first burner 27a and the plurality of second burners 27b each have an air flow path frame 28 through which air can flow and which can inject air into the cylinder 25, and a nozzle 29 capable of injecting fuel into the air flow path frame 28. The fuel supply system 30 includes a first fuel line 31 connected to a supply source of the first fuel NG and through which the first fuel NG can flow, a second fuel line 32 connected to a supply source of the second fuel HG and through which the second fuel HG can flow, a first fuel valve 33 provided in the first fuel line 31, a second fuel valve 34 provided in the second fuel line 32, a header line 36 through which the first fuel NG and the second fuel HG can flow, branch lines 38 branching from the header line 36 for each of the plurality of burners 27, and a gate valve 37a provided in the header line 36 and capable of dividing the header line 36 into a first header section 36a and a second header section 36b. A first branch line 38a, which is one of the branch lines 38 for each of the plurality of burners 27, branches from the first header section 36a. The first branch line 38a is connected to a first nozzle 29a, which is the nozzle 29 of the first burner 27a. From the second header section 36b, a plurality of second branch lines 38b, excluding the first branch line 38a, branch out from the branch lines 38 for each of the plurality of burners 27. Each of the plurality of second branch lines 38b is connected to a second nozzle 29b, which is the nozzle 29 for each of the plurality of second burners 27b. The first fuel line 31 is connected to the first header section 36a, and the second fuel line 32 is connected to the second header section 36b.

[0130] In this aspect, the first fuel NG is ejected from the first nozzle 29 a, and while this first fuel NG is being combusted, the second fuel HG is ejected from the second nozzle 29 b, and this second fuel HG can be combusted. Therefore, in this aspect, even if one of the two types of fuel has inferior fuel characteristics to the other fuel, this can be compensated for by the combustion of the other fuel, and therefore stable combustion of the fuels can be achieved even during the fuel switching process.

[0131] (8) A gas turbine facility according to an eighth aspect includes, in addition to the first gate valve serving as the gate valve 37a in the gas turbine facility according to the seventh aspect, a second gate valve 37b provided in the second header section 36b and capable of dividing the second header section 36b into a first-side second header section 36bi on the side of the first header section 36a and a second-side second header section 36bo that is the remaining portion of the second header section 36b. A first-side second branch line 38bi that is one of the second branch lines 38b branches off from the first-side second header section 36bi. A first-side second nozzle 29bi that is one of the second nozzles 29b for each of the second burners 27b is connected to the first-side second branch line 38bi. A plurality of second-side second branch lines 38bo, which are the second branch lines 38b excluding the first-side second branch line 38bi, branch off from the second-side second header section 36bo. Second-side second nozzles 29bo, which are the second nozzles 29b excluding the first-side second nozzles 29bi, of the second nozzles 29b of the plurality of second burners 27b, are connected to the second-side second branch lines 38bo. The second fuel line 32 is connected to the second-side second header section 36bo.

[0132] The gas turbine equipment of this aspect has a first gate valve 37a and a second gate valve 37b as valves that gate the header line 36. Therefore, the flow path in the header line 36 can be partitioned at two positions. Therefore, the number of nozzles 29 into which the first fuel NG flows from the header line 36 and the number of nozzles 29 into which the second fuel HG flows from the header line 36 can be changed as needed. Therefore, in this aspect, the manner of fuel switching can be changed as needed.

[0133] (9) A gas turbine facility according to a ninth aspect is the gas turbine facility according to the seventh or eighth aspect, further comprising: a connecting line 35 that connects, in the first fuel line 31, a position between a position where the first fuel line 31 is connected to the header line 36 and a position where the first fuel valve 33 is provided, and, in the second fuel line 32, a position between a position where the second fuel line 32 is connected to the header line 36 and a position where the second fuel valve 34 is provided; and a mixing ratio control valve 35v that is provided in the connecting line 35 and can adjust the flow rate of fuel flowing through the connecting line 35.

[0134] In this aspect, the first fuel line 31 and the second fuel line 32 are connected by the connecting line 35, so that a mixed fuel of the first fuel NG and the second fuel HG can be made to flow into the header line 36. Therefore, in this aspect, the mixed fuel can be injected from the nozzles 29 and burned. Furthermore, in this aspect, the first fuel NG can be made to flow into the entire header line 36 so that the first fuel NG can be ejected from all the nozzles 29, and the second fuel HG can be made to flow into the entire header line 36 so that the second fuel HG can be ejected from all the nozzles 29. Furthermore, in this aspect, the mixed fuel can be made to flow into the entire header line 36 so that the mixed fuel can be ejected from all the nozzles 29.

[0135] (10) A gas turbine facility according to a tenth aspect is the gas turbine facility according to any one of the seventh to ninth aspects, further comprising a control device 50. The control device 50 is capable of executing a fuel switching step of switching the fuel supplied to the combustor 20 from the first fuel NG to the second fuel HG by controlling the first fuel valve 33, the second fuel valve 34, and the gate valve 37a. The fuel switching process includes a first fuel exclusive combustion process S1 in which the first fuel valve 33 is opened, the second fuel valve 34 is closed, and the gate valve is closed, thereby supplying only the first fuel NG to the first nozzle 29a and not supplying the first fuel NG or the second fuel HG to the second nozzle 29b; and a multi-fuel combustion process S2 in which, after the first fuel exclusive combustion process S1, the first fuel valve 33 is opened, the second fuel valve 34 is opened, and the gate valve is closed, thereby supplying only the first fuel NG to the first nozzle 29a and supplying only the second fuel HG to the second nozzle 29b. and a second fuel exclusive combustion preparation step S3 in which, after the mixed combustion step S2, the first fuel valve 33 is closed, the second fuel valve 34 is open, and the gate valve is closed, so that the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a, and the second fuel HG is supplied only to the second nozzle 29b. And a second fuel exclusive combustion step S4 in which, after the second fuel exclusive combustion preparation step S3, the first fuel valve 33 is closed, the second fuel valve 34 is open, and the gate valve is open, so that only the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b.

[0136] In this aspect, the operating method in the first aspect can be executed, and therefore, in this aspect, the fuel can be stably combusted during the fuel switching process, similar to the operating method in the first aspect.

[0137] (11) A gas turbine facility according to an eleventh aspect is the gas turbine facility according to the eighth aspect, further comprising a control device 50. The control device 50 is capable of executing a first fuel switching process and a second fuel switching process of switching the fuel supplied to the combustor 20 from the first fuel NG to the second fuel HG by controlling the first fuel valve 33, the second fuel valve 34, the first gate valve 37a, and the second gate valve 37b. The first fuel switching process includes a first fuel exclusive combustion process S1 in which the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is closed, and the second gate valve 37b is opened, thereby supplying only the first fuel NG to the first nozzle 29a and not supplying the first fuel NG or the second fuel HG to the second nozzle 29b; and a multi-fuel combustion process S2 in which, after the first fuel exclusive combustion process S1, the first fuel valve 33 is opened, the second fuel valve 34 is opened, the first gate valve 37a is closed, and the second gate valve 37b is opened, thereby supplying only the first fuel NG to the first nozzle 29a and supplying only the second fuel HG to the second nozzle 29b. and a second-fuel exclusive-combustion preparation step S3 in which, after the mixed combustion step S2, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is closed, and the second gate valve 37b is open, so that the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a, and the second fuel HG is supplied only to the second nozzle 29b; and a second-fuel exclusive-combustion step S4 in which, after the second-fuel exclusive-combustion preparation step S3, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, and the second gate valve 37b is open, so that only the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b.The second fuel switching step includes a first fuel exclusive combustion step S1a in which the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is opened, and the second gate valve 37b is closed, thereby supplying only the first fuel NG to the first nozzle 29a and the first-side second nozzle 29bi, and not supplying the first fuel NG or the second fuel HG to the second-side second nozzle 29bo; and after the first fuel exclusive combustion step S1a, the first fuel valve 33 is opened, the second fuel valve 34 is opened, the first gate valve 37a is closed, and the second gate valve 37b is opened, thereby supplying only the first fuel NG to the first nozzle 29a, and supplying only the second fuel HG to the second nozzle 29b. a second-fuel exclusive-combustion preparation step S3a in which, after the second-fuel exclusive-combustion preparation step S2a, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is closed, and the second gate valve 37b is open, so that the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a, and the second fuel HG is supplied only to the second nozzle 29b; and a second-fuel exclusive-combustion step S4a in which, after the second-fuel exclusive-combustion preparation step S3a, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, and the second gate valve 37b is open, so that only the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b.

[0138] In this aspect, similarly to the operating method in the second aspect, in addition to the first fuel switching step, a second fuel switching step can also be executed, and the mode of fuel switching can be changed as appropriate.

[0139] (12) A gas turbine facility according to a twelfth aspect is the gas turbine facility according to the tenth or eleventh aspect, further comprising a control device 50. The control device 50 is capable of executing a first fuel switching process and a third fuel switching process of switching the fuel supplied to the combustor 20 from the first fuel NG to the second fuel HG by controlling the first fuel valve 33, the second fuel valve 34, the first gate valve 37a, and the second gate valve 37b. The first fuel switching process includes a first fuel exclusive combustion process S1 in which the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is closed, and the second gate valve 37b is opened, thereby supplying only the first fuel NG to the first nozzle 29a and not supplying the first fuel NG or the second fuel HG to the second nozzle 29b; and a multi-fuel combustion process S2 in which, after the first fuel exclusive combustion process S1, the first fuel valve 33 is opened, the second fuel valve 34 is opened, the first gate valve 37a is closed, and the second gate valve 37b is opened, thereby supplying only the first fuel NG to the first nozzle 29a and supplying only the second fuel HG to the second nozzle 29b. and a second-fuel exclusive-combustion preparation step S3 in which, after the mixed combustion step S2, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is closed, and the second gate valve 37b is open, so that the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a, and the second fuel HG is supplied only to the second nozzle 29b; and a second-fuel exclusive-combustion step S4 in which, after the second-fuel exclusive-combustion preparation step S3, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, and the second gate valve 37b is open, so that only the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b.The third fuel switching step includes a first fuel exclusive combustion step S1b in which the first fuel valve 33 is opened, the second fuel valve 34 is closed, the first gate valve 37a is opened, and the second gate valve 37b is closed, thereby supplying only the first fuel NG to the first nozzle 29a and the first-side second nozzle 29bi, and not supplying the first fuel NG and the second fuel HG to the second-side second nozzle 29bo; and a second fuel exclusive combustion step S1b in which, after the first fuel exclusive combustion step S1b, the first fuel valve 33 is opened, the second fuel valve 34 is opened, the first gate valve 37a is opened, and the second gate valve 37b is closed, thereby supplying only the first fuel NG to the first nozzle 29a and the first-side second nozzle 29bi, and not supplying the first fuel NG and the second fuel HG to the second-side second nozzle 29bo. the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a, and the second fuel HG is supplied only to the second nozzle 29b; and a second fuel exclusive combustion preparation process S4b, after the second fuel exclusive combustion preparation process S3b, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, and the second gate valve 37b is closed, so that the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a, and the second fuel exclusive combustion process S4b, after the second fuel exclusive combustion preparation process S3b, the first fuel valve 33 is closed, the second fuel valve 34 is open, the first gate valve 37a is open, and the second gate valve 37b is open, so that the second fuel HG is supplied only to the first nozzle 29a and the second nozzle 29b.

[0140] In this aspect, similarly to the operating method in the third aspect, in addition to the first fuel switching step, a third fuel switching step can also be executed, and the mode of fuel switching can be changed as appropriate.

[0141] (13) A gas turbine facility according to a thirteenth aspect is the gas turbine facility according to the ninth aspect, further comprising a control device 50. The control device 50 controls the first fuel valve 33, the second fuel valve 34, the gate valve 37a, and the mixture ratio adjustment valve 35v, and is capable of executing a first fuel switching process and a fourth fuel switching process of switching the fuel supplied to the combustor 20 from the first fuel NG to the second fuel HG. The first fuel switching step includes a first fuel exclusive combustion step S1 in which the first fuel valve 33 is opened, the second fuel valve 34 is closed, the gate valve 37a is closed, and the mixture ratio adjustment valve 35v is closed, thereby supplying only the first fuel NG to the first nozzle 29a and not supplying the first fuel NG or the second fuel HG to the second nozzle 29b; and a multi-fuel combustion step S2 in which, after the first fuel exclusive combustion step S1, the first fuel valve 33 is opened, the second fuel valve 34 is opened, the gate valve 37a is closed, and the mixture ratio adjustment valve 35v is closed, thereby supplying only the first fuel NG to the first nozzle 29a and supplying only the second fuel HG to the second nozzle 29b. and a second-fuel exclusive-combustion preparation step S3 in which, after the mixed combustion step S2, the first fuel valve 33 is closed, the second fuel valve 34 is open, the gate valve 37a is closed, and the mixture ratio adjustment valve 35v is closed, so that the first fuel NG and the second fuel HG are not supplied to the first nozzle 29a, and the second fuel HG is supplied only to the second nozzle 29b; and a second-fuel exclusive-combustion step S4 in which, after the second-fuel exclusive-combustion preparation step S3, the first fuel valve 33 is closed, the second fuel valve 34 is open, the gate valve 37a is open, and the mixture ratio adjustment valve 35v is closed, so that only the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b.The fourth fuel switching step includes a first fuel exclusive combustion step S1c in which the first fuel valve 33 is opened, the second fuel valve 34 is closed, the gate valve is opened, and the mixture ratio adjustment valve 35v is closed, and only the first fuel NG is supplied to the first nozzle 29a and the second nozzle 29b; and after the first fuel exclusive combustion step S1c, the first fuel valve 33 is opened, the second fuel valve 34 is opened, the gate valve is opened, and the mixture ratio adjustment valve 35v is opened, and only the first fuel NG is supplied to the first nozzle 29a and the second nozzle 29b. The method includes a mixed fuel combustion process S2c in which a mixed fuel obtained by mixing the first fuel NG and the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b, and a second fuel exclusive combustion process S4c in which, after the mixed fuel combustion process S2c, the first fuel valve 33 is closed, the second fuel valve 34 is opened, the gate valve is opened, and the mixture ratio adjustment valve 35v is opened, and only the second fuel HG is supplied to the first nozzle 29a and the second nozzle 29b.

[0142] In this aspect, similarly to the operating method in the fourth aspect, in addition to the first fuel switching step, a fourth fuel switching step can also be executed, and the mode of fuel switching can be changed as appropriate.

[0143] (14) A gas turbine facility according to a fourteenth aspect is the gas turbine facility according to any one of the seventh to thirteenth aspects, wherein the combustor 20 has a plurality of burner groups 26. Each of the plurality of burner groups 26 has the first burner 27 a and the plurality of second burners 27 b arranged around the first burner 27 a.

[0144] (15) A gas turbine facility according to a fifteenth aspect is the gas turbine facility according to any one of the eighth, eleventh, and twelfth aspects, wherein the combustor 20 has a plurality of burner groups 26. The plurality of burner groups 26 include an inner burner group 26i and a plurality of outer burner groups 26o arranged around the inner burner group 26i. Each of the plurality of burner groups 26 has the first nozzle 29a and the second nozzle 29b arranged around the first nozzle 29a. The first-side second nozzle 29bi is the second nozzle 29b included in the inner burner group 26i. The second-side second nozzle 29bo is the second nozzle 29b included in each of the plurality of outer burner groups 26o.

[0145] According to one aspect of the present disclosure, fuel can be stably burned even during the fuel switching process.

[0146] 1: Gas turbine 2: Gas turbine rotor 3: Intermediate casing 10: Compressor 11: Compressor rotor 12: Compressor casing 15: Turbine 16: Turbine rotor 17: Turbine casing 20: Combustor 21: Outer casing 22: End cover 23: Inner casing 24: Air hole plate 24h: Air hole 25: Combustor casing (or simply casing) 26: Burner group 26i: Inner burner group 26o: Outer burner group 27: Burner 27a: First burner 27b: Second burner 28: Air flow path frame 28a: First air flow path frame 28b: Second air flow path frame 29: Nozzle 29a: First nozzle 29b: Second nozzle 29bi: First side second nozzle 29bo: Second side second nozzle 30: Fuel supply system 31: First fuel line 32: Second fuel line 33: First fuel valve 34: Second fuel valve 34a: Downstream side second fuel valve 35: Connecting line 35v: Mixing ratio control valve 36: Header line 36a: First header section 36b: Second header section 36bi: First side second header section 36bo: Second side second header section 36x: Integrated line 37a: First gate valve (or simply gate valve) 37b: Second gate valve 38: Branch lines 38a: First branch line 38b: Second branch line 38bi: First side second branch line 38bo: Second side second branch line 39: Nozzle valve 50: Control device 51: Heat generation amount calculator 52: Valve control amount calculator 53: Valve signal generator A: Air Acom: Compressed air F: Fuel CG: Combustion gas NG: First fuel HG: Second fuel Ar: Rotor axis Ac: Combustor axis Da: Rotor axial direction Dau: Axial upstream side Dad: Axial downstream side Dc: Combustor axial direction Dcb: Base end side Dct: Tip end side

Claims

1. A method for operating a gas turbine comprising: a compressor capable of compressing air to generate compressed air; a combustor capable of burning fuel in the compressed air to generate combustion gas; and a turbine capable of being driven by the combustion gas, wherein the combustor has a cylinder capable of burning fuel, and a plurality of burners capable of injecting fuel together with the compressed air into the cylinder, the plurality of burners including a first burner and a plurality of second burners excluding the first burner, and each of the first burner and the plurality of second burners has an air flow path frame through which air can flow and capable of injecting air into the cylinder, and a nozzle capable of injecting fuel into the air flow path frame, the method comprising: executing a fuel switching step of switching the fuel supplied to the combustor from a first fuel to a second fuel, the fuel switching step including: a first fuel exclusive combustion step of supplying only the first fuel to a first nozzle that is the nozzle of the first burner, and supplying neither the first fuel nor the second fuel to a second nozzle that is the nozzle of each of the plurality of second burners; a mixed fuel combustion step of supplying only the first fuel to the first nozzle and supplying only the second fuel to the second nozzle after the mixed fuel combustion step; a second fuel exclusive combustion preparation step of not supplying the first fuel and the second fuel to the first nozzle and supplying the second fuel only to the second nozzle after the mixed fuel combustion step; and a second fuel exclusive combustion step of supplying only the second fuel to the first nozzle and the second nozzle after the second fuel exclusive combustion preparation step.

2. A method for operating a gas turbine as defined in claim 1, further comprising the step of executing a second fuel switching step in addition to a first fuel switching step which is the fuel switching step, the second fuel switching step including: a first fuel exclusive combustion step of supplying only the first fuel to a first side second nozzle and the first nozzle which are a part of the second nozzles of each of the plurality of second burners, and not supplying the first fuel and the second fuel to a plurality of second side second nozzles excluding the first side second nozzles of each of the plurality of second burners; a mixed combustion step of supplying only the first fuel to the first nozzle and supplying only the second fuel to the second nozzle after the first fuel exclusive combustion step; a second fuel exclusive combustion preparation step of not supplying the first fuel and the second fuel to the first nozzle after the mixed combustion step, and supplying the second fuel only to the second side second nozzle; and a second fuel exclusive combustion step of supplying only the second fuel to the first nozzle and the second side second nozzle after the second fuel exclusive combustion preparation step.

3. A method for operating a gas turbine as defined in claim 1, further comprising the step of executing a third fuel switching step in addition to a first fuel switching step which is the fuel switching step, the third fuel switching step including: a first fuel exclusive combustion step of supplying only the first fuel to a first side second nozzle and the first nozzle which are a part of the second nozzles of each of the plurality of second burners, and not supplying the first fuel and the second fuel to a plurality of second side second nozzles excluding the first side second nozzle among the second nozzles of each of the plurality of second burners; a mixed combustion step of supplying only the first fuel to the first nozzle and the first side second nozzle and supplying only the second fuel to the second side second nozzle after the first fuel exclusive combustion step; a second fuel exclusive combustion preparation step of not supplying the first fuel and the second fuel to the first nozzle after the mixed combustion step, and supplying the second fuel only to the second side second nozzle; and a second fuel exclusive combustion step of supplying only the second fuel to the first nozzle and the second side second nozzle after the second fuel exclusive combustion preparation step.

4. A method for operating a gas turbine as defined in claim 1, further comprising the step of executing a fourth fuel switching step in addition to a first fuel switching step which is the fuel switching step, the fourth fuel switching step including: a first fuel exclusive combustion step of supplying only the first fuel to the first nozzle and the second nozzle; a mixed fuel combustion step of supplying a mixed fuel of the first fuel and the second fuel to the first nozzle and the second nozzle after the first fuel exclusive combustion step; and a second fuel exclusive combustion step of supplying only the second fuel to the first nozzle and the second nozzle after the mixed fuel combustion step.

5. A method for operating a gas turbine according to any one of claims 1 to 4, wherein the combustor has a plurality of burner groups, each of the plurality of burner groups has the first nozzle and the second nozzle arranged around the first nozzle, the first fuel is natural gas, and the second fuel is hydrogen gas.

6. A method for operating a gas turbine as claimed in claim 2 or 3, wherein the combustor has a plurality of burner groups, the plurality of burner groups having an inner burner group and a plurality of outer burner groups arranged around the inner burner group, each of the plurality of burner groups having the first nozzle and the second nozzle arranged around the first nozzle, the first side second nozzle is the second nozzle of the inner burner group, the plurality of second side second nozzles are the second nozzles respectively possessed by the plurality of outer burner groups, the first fuel is natural gas, and the second fuel is hydrogen gas.

7. A combustion apparatus comprising: a compressor capable of compressing air to generate compressed air; a combustor capable of burning fuel in the compressed air to generate combustion gas; a turbine capable of being driven by the combustion gas; and a fuel supply system capable of supplying a first fuel and a second fuel to the combustor, wherein the combustor has a cylinder in which fuel can be burned, and a plurality of burners capable of injecting fuel together with compressed air into the cylinder, the plurality of burners including a first burner and a plurality of second burners excluding the first burner, wherein the first burner and the plurality of second burners each have an air flow path frame through which air can flow and which can inject air into the cylinder, and a nozzle capable of injecting fuel into the air flow path frame, and wherein the fuel supply system comprises: a first fuel line connected to a supply source of the first fuel and through which the first fuel can flow; a second fuel line connected to a supply source of the second fuel and through which the second fuel can flow; a first fuel valve provided in the first fuel line; and a second fuel valve provided in the second fuel line.

1. A gas turbine facility comprising: a header line through which the first fuel and the second fuel can flow; branch lines branching off from the header line for each of the plurality of burners; and a gate valve provided in the header line and capable of dividing the header line into a first header section and a second header section, wherein a first branch line which is a part of the branch lines for each of the plurality of burners branches off from the first header section, and the first branch line is connected to a first nozzle which is the nozzle of the first burner, and a plurality of second branch lines excluding the first branch line branch off from the second header section, and each of the plurality of second branch lines is connected to a second nozzle which is the nozzle for each of the plurality of second burners, and the first fuel line is connected to the first header section and the second fuel line is connected to the second header section.

8. A gas turbine facility as claimed in claim 7, further comprising, in addition to the first gate valve which is the gate valve, a second gate valve which is provided in the second header section and which can divide the second header section into a first-side second header section on the side of the first header section and a second-side second header section which is the remaining section of the second header section, a first-side second branch line which is a part of the second branch lines among the plurality of second branch lines branches off from the first-side second header section, and a first-side second nozzle which is a part of the second nozzles of each of the plurality of second burners is connected to the first-side second branch line, a plurality of second-side second branch lines which are second branch lines excluding the first-side second branch line among the plurality of second branch lines branch off from the second-side second header section, and a second-side second nozzle which is a second nozzle excluding the first-side second nozzle among the second nozzles of each of the plurality of second burners is connected to the second-side second branch line, and the second fuel line is connected to the second-side second header section.

9. The gas turbine equipment according to claim 7, comprising: a connecting line connecting a position in the first fuel line between a position where the first fuel line is connected to the header line and a position where the first fuel valve is provided, and a position in the second fuel line between a position where the second fuel line is connected to the header line and a position where the second fuel valve is provided; and a mixture ratio control valve provided in the connecting line, capable of adjusting the flow rate of fuel flowing through the connecting line.

10. A gas turbine facility according to claim 7, further comprising a control device, the control device being capable of executing a fuel switching process for switching the fuel supplied to the combustor from the first fuel to the second fuel by controlling the first fuel valve, the second fuel valve, and the gate valve, the fuel switching process including: a first fuel exclusive combustion process for supplying only the first fuel to the first nozzle and neither the first fuel nor the second fuel to the second nozzle by opening the first fuel valve, closing the second fuel valve, and closing the gate valve; and a multi-fuel combustion process for supplying only the first fuel to the first nozzle and only the second fuel to the second nozzle after the first fuel exclusive combustion process by opening the first fuel valve, opening the second fuel valve, and closing the gate valve. a second fuel exclusive combustion preparation step of, after the mixed combustion step, closing the first fuel valve, opening the second fuel valve, and closing the gate valve, thereby not supplying the first fuel and the second fuel to the first nozzle, and supplying the second fuel only to the second nozzle; and a second fuel exclusive combustion step of, after the second fuel exclusive combustion preparation step, closing the first fuel valve, opening the second fuel valve, and opening the gate valve, thereby supplying only the second fuel to the first nozzle and the second nozzle.

11. A gas turbine facility according to claim 8, further comprising a control device, the control device being capable of executing a first fuel switching process and a second fuel switching process for switching the fuel supplied to the combustor from the first fuel to the second fuel by controlling the first fuel valve, the second fuel valve, the first gate valve, and the second gate valve, the first fuel switching process including: a first fuel exclusive combustion process in which the first fuel valve is opened, the second fuel valve is closed, the first gate valve is closed, and the second gate valve is opened, thereby supplying only the first fuel to the first nozzle, and neither the first fuel nor the second fuel is supplied to the second nozzle; and a multi-fuel combustion process in which, after the first fuel exclusive combustion process, the first fuel valve is opened, the second fuel valve is opened, the first gate valve is closed, and the second gate valve is opened, thereby supplying only the first fuel to the first nozzle, and supplying only the second fuel to the second nozzle. a second fuel exclusive combustion preparation step of, after the mixed combustion step, closing the first fuel valve, opening the second fuel valve, closing the first gate valve, and opening the second gate valve to not supply the first fuel and the second fuel to the first nozzle, and supplying the second fuel only to the second nozzle; and a second fuel exclusive combustion step of, after the second fuel exclusive combustion preparation step, closing the first fuel valve, opening the second fuel valve, opening the first gate valve, and opening the second gate valve to supply only the second fuel to the first nozzle and the second nozzle, wherein the second fuel switching step includes: a first fuel exclusive combustion step of, after the mixed combustion step, closing the first fuel valve, closing the second fuel valve, opening the first gate valve, and closing the second gate valve to supply only the first fuel to the first nozzle and the first side second nozzle, and not supplying the first fuel and the second fuel to the second side second nozzle; a multi-fuel combustion step of supplying only the first fuel to the first nozzle and supplying only the second fuel to the second nozzle by opening the first fuel valve, opening the second fuel valve, closing the first gate valve, and opening the second gate valve after the first fuel mono-fuel combustion step;a second fuel exclusive combustion preparation process of, after the mixed combustion process, closing the first fuel valve, opening the second fuel valve, closing the first gate valve, and opening the second gate valve, thereby not supplying the first fuel and the second fuel to the first nozzle, and supplying the second fuel only to the second nozzle; and a second fuel exclusive combustion process of, after the second fuel exclusive combustion preparation process, closing the first fuel valve, opening the second fuel valve, opening the first gate valve, and opening the second gate valve, thereby supplying only the second fuel to the first nozzle and the second nozzle.

12. A gas turbine facility according to claim 8, further comprising a control device, the control device being capable of executing a first fuel switching process and a third fuel switching process for switching the fuel supplied to the combustor from the first fuel to the second fuel by controlling the first fuel valve, the second fuel valve, the first gate valve, and the second gate valve, the first fuel switching process including: a first fuel exclusive combustion process in which the first fuel valve is opened, the second fuel valve is closed, the first gate valve is closed, and the second gate valve is opened, thereby supplying only the first fuel to the first nozzle, and neither the first fuel nor the second fuel is supplied to the second nozzle; and a multi-fuel combustion process in which, after the first fuel exclusive combustion process, the first fuel valve is opened, the second fuel valve is opened, the first gate valve is closed, and the second gate valve is opened, thereby supplying only the first fuel to the first nozzle, and supplying only the second fuel to the second nozzle. a second fuel exclusive combustion preparation step of, after the mixed combustion step, closing the first fuel valve, opening the second fuel valve, closing the first gate valve, and opening the second gate valve to not supply the first fuel and the second fuel to the first nozzle, and supplying the second fuel only to the second nozzle; and a second fuel exclusive combustion step of, after the second fuel exclusive combustion preparation step, closing the first fuel valve, opening the second fuel valve, opening the first gate valve, and opening the second gate valve to supply only the second fuel to the first nozzle and the second nozzle, wherein the third fuel switching step includes: a first fuel exclusive combustion step of, opening the first fuel valve, closing the second fuel valve, opening the first gate valve, and closing the second gate valve to supply only the first fuel to the first nozzle and the first side second nozzle, and not supplying the first fuel and the second fuel to the second side second nozzle; a multi-fuel combustion step of supplying only the first fuel to the first nozzle and the first-side second nozzle and supplying only the second fuel to the second-side second nozzle by opening the first fuel valve, opening the second fuel valve, opening the first gate valve, and closing the second gate valve after the first fuel mono-fuel combustion step;a second fuel exclusive combustion preparation process of, after the mixed combustion process, closing the first fuel valve, opening the second fuel valve, opening the first gate valve, and closing the second gate valve, thereby not supplying the first fuel and the second fuel to the first nozzle, and supplying the second fuel only to the second nozzle; and a second fuel exclusive combustion process of, after the second fuel exclusive combustion preparation process, closing the first fuel valve, opening the second fuel valve, opening the first gate valve, and opening the second gate valve, thereby supplying only the second fuel to the first nozzle and the second nozzle.

13. A gas turbine facility according to claim 9, further comprising a control device, the control device being capable of executing a first fuel switching process and a fourth fuel switching process for switching the fuel supplied to the combustor from the first fuel to the second fuel by controlling the first fuel valve, the second fuel valve, the gate valve, and the mixture ratio adjustment valve, the first fuel switching process including: a first fuel exclusive combustion process in which the first fuel valve is opened, the second fuel valve is closed, the gate valve is closed, and the mixture ratio adjustment valve is closed, thereby supplying only the first fuel to the first nozzle, and neither the first fuel nor the second fuel is supplied to the second nozzle; and a multi-fuel combustion process in which, after the first fuel exclusive combustion process, the first fuel valve is opened, the second fuel valve is opened, the gate valve is closed, and the mixture ratio adjustment valve is closed, thereby supplying only the first fuel to the first nozzle, and supplying only the second fuel to the second nozzle. a second fuel exclusive combustion preparation step of, after the mixed combustion step, closing the first fuel valve, opening the second fuel valve, closing the gate valve, and closing the mixture ratio adjustment valve, thereby not supplying the first fuel and the second fuel to the first nozzle, and supplying the second fuel only to the second nozzle; and a second fuel exclusive combustion step of, after the second fuel exclusive combustion preparation step, closing the first fuel valve, opening the second fuel valve, opening the gate valve, and closing the mixture ratio adjustment valve, thereby supplying only the second fuel to the first nozzle and the second nozzle; the fourth fuel switching step includes: a first fuel exclusive combustion step of, after the mixed combustion step, opening the first fuel valve, closing the second fuel valve, opening the gate valve, and closing the mixture ratio adjustment valve, thereby supplying only the first fuel to the first nozzle and the second nozzle; a mixed fuel combustion process of supplying a mixed fuel of the first fuel and the second fuel to the first nozzle and the second nozzle by opening the first fuel valve, opening the second fuel valve, opening the gate valve, and opening the mixture ratio control valve after the first fuel exclusive combustion process; and a second fuel exclusive combustion process of supplying only the second fuel to the first nozzle and the second nozzle by closing the first fuel valve, opening the second fuel valve, opening the gate valve, and opening the mixture ratio control valve after the mixed fuel exclusive combustion process.

14. Gas turbine equipment according to any one of claims 7 to 13, wherein the combustor has a plurality of burner groups, and each of the plurality of burner groups has the first burner and a plurality of second burners arranged around the first burner.

15. Gas turbine equipment according to any one of claims 8, 11 and 12, wherein the combustor has a plurality of burner groups, the plurality of burner groups having an inner burner group and a plurality of outer burner groups arranged around the inner burner group, each of the plurality of burner groups having the first nozzle and the second nozzle arranged around the first nozzle, the first side second nozzle being the second nozzle of the inner burner group, and the second side second nozzle being the second nozzle of each of the plurality of outer burner groups.