Gas turbine operation method

Abstract

An operation method for a gas turbine according to one embodiment is for a gas turbine provided with a combustor that has a main nozzle and a pilot nozzle and that is capable of using, as fuel, hydrogen and a fuel other than hydrogen. In the operation method for the gas turbine according to said one embodiment, with regard to the ratio of the hydrogen co-combustion rate of the fuel injected from the pilot nozzle to the hydrogen co-combustion rate of the fuel injected from the main nozzle, when compared with a first ratio during operation at a low hydrogen co-combustion rate, a second ratio during operation at a high hydrogen co-combustion rate, during which the hydrogen co-combustion rate is higher than that during the operation at the low hydrogen co-combustion rate, is higher.

Description

[Technical Field]

[0001] The present disclosure relates to a method of operating a gas turbine. This application claims priority based on Japanese Patent Application No. 2022-192566, filed with the Japan Patent Office on December 1, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] For example, in thermal power plants, measures to reduce carbon dioxide (CO2) emissions, which cause global warming, are being considered, including improving power generation efficiency and actively using fuels other than fossil fuels, such as hydrogen (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-046949 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to reduce carbon dioxide emissions, it is desirable to increase the hydrogen co-firing ratio. However, because hydrogen has low ignition energy and a fast combustion speed, increasing the hydrogen co-firing ratio increases the possibility of flame backflow and other problems.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to increase the hydrogen-mixed combustion ratio while suppressing flame backflow and the like during operation of a gas turbine. [Means for solving the problem]

[0006] (1) A method of operating a gas turbine according to at least one embodiment of the present disclosure, comprising: A method for operating a gas turbine having a combustor that has a main nozzle and a pilot nozzle and that can use hydrogen and a fuel other than hydrogen as fuel, comprising the steps of: The ratio of the hydrogen mixing ratio of the fuel injected from the pilot nozzle to the hydrogen mixing ratio of the fuel injected from the main nozzle is a second ratio during high hydrogen mixing ratio operation, in which the hydrogen mixing ratio is higher than that during low hydrogen mixing ratio operation, which is larger than a first ratio during low hydrogen mixing ratio operation. [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, during operation of a gas turbine, it is possible to increase the hydrogen-mixed combustion ratio while suppressing flame backflow and the like. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating a gas turbine according to some embodiments. [Figure 2] 1 is a cross-sectional view of a combustor according to some embodiments. [Figure 3] 1 is a cross-sectional view illustrating a main portion of a combustor according to some embodiments. [Figure 4] FIG. 2 is a diagram schematically illustrating an arrangement of fuel injectors in a combustor according to some embodiments, viewed from the downstream side to the upstream side along the axial direction of the combustor. [Figure 5] FIG. 2 is a schematic diagram of a fuel supply system for a combustor according to some embodiments. [Figure 6A] 1 is a graph showing an example of the relationship between the hydrogen mixing ratio of each combustion burner and the hydrogen mixing ratio of the entire combustor during rated operation. [Figure 6B] 6B is a graph showing an example of the relationship between the ratio of the hydrogen mixing ratio in the pilot combustion burner to the hydrogen mixing ratio in the main combustion burner and the hydrogen mixing ratio in the entire combustor, when the hydrogen mixing ratios of each combustion burner and the hydrogen mixing ratio in the entire combustor have the relationship shown in FIG. 6A . [Figure 7A] 10 is a graph showing another example of the relationship between the hydrogen mixing ratio of each combustion burner and the hydrogen mixing ratio of the entire combustor during rated operation. [Figure 7B] 7B is a graph showing an example of the relationship between the ratio of the hydrogen mixing ratio in the pilot combustion burner to the hydrogen mixing ratio in the main combustion burner and the hydrogen mixing ratio in the entire combustor, when the hydrogen mixing ratios of each combustion burner and the hydrogen mixing ratio in the entire combustor have the relationship shown in FIG. 7A. [Figure 8A] 10 is a graph showing yet another example of the relationship between the hydrogen mixing ratio of each combustion burner and the hydrogen mixing ratio of the entire combustor during rated operation. [Figure 8B] 8B is a graph showing an example of the relationship between the ratio of the hydrogen mixing ratio in the pilot combustion burner to the hydrogen mixing ratio in the main combustion burner and the hydrogen mixing ratio in the entire combustor, when the hydrogen mixing ratios of each combustion burner and the hydrogen mixing ratio in the entire combustor have the relationship shown in FIG. 8A. [Figure 9A] 10 is a graph showing an example of the relationship between the hydrogen mixing ratio of each combustion burner and the hydrogen mixing ratio of the entire combustor during partial load operation. [Figure 9B] 9B is a graph showing an example of the relationship between the ratio of the hydrogen mixing ratio in the pilot combustion burner to the hydrogen mixing ratio in the main combustion burner and the hydrogen mixing ratio in the entire combustor, when the hydrogen mixing ratios of each combustion burner and the entire combustor have the relationship shown in FIG. 9A . DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0010] (Regarding Gas Turbine 1) FIG. 1 is a schematic configuration diagram showing a gas turbine 1 according to some embodiments. A gas turbine, which is an example of an application of a gas turbine operation method according to some embodiments, will be described with reference to FIG.

[0011] 1, a gas turbine 1 operated by a gas turbine operating method according to some embodiments includes a compressor 2 for generating compressed air as an oxidant, a gas turbine combustor 4 for generating combustion gas using the compressed air and fuel, and a turbine 6 configured to be rotationally driven by the combustion gas. In the case of a gas turbine 1 for power generation, a generator (not shown) is connected to the turbine 6, and power is generated by the rotational energy of the turbine 6. In the following description, the gas turbine combustor 4 will also be simply referred to as the combustor 4.

[0012] Specific configuration examples of each part of the gas turbine 1 according to some embodiments will be described. A compressor 2 according to some embodiments includes a compressor casing 10, an air intake 12 provided on the inlet side of the compressor casing 10 for taking in air, a rotor 8 provided to penetrate both the compressor casing 10 and a turbine casing 22 (described later), and various blades arranged within the compressor casing 10. The various blades include an inlet guide vane 14 provided on the air intake 12 side, a plurality of stator vanes 16 fixed to the compressor casing 10 side, and a plurality of rotor blades 18 implanted on the rotor 8 so as to be arranged alternately with respect to the stator vanes 16. The compressor 2 may also include other components such as an unillustrated bleed chamber. In this compressor 2, air taken in through the air intake 12 is compressed as it passes through the plurality of stator vanes 16 and the plurality of rotor blades 18, thereby becoming high-temperature, high-pressure compressed air. The high-temperature, high-pressure compressed air is then sent from the compressor 2 to a downstream combustor 4.

[0013] The combustor 4 according to some embodiments is disposed within the casing 20. As shown in FIG. 1 , a plurality of combustors 4 may be disposed annularly within the casing 20 around the rotor 8. Fuel and compressed air generated by the compressor 2 are supplied to the combustor 4, and the combustor 4 burns the fuel to generate combustion gas, which is a working fluid for the turbine 6. The combustion gas is then sent from the combustor 4 to the turbine 6 at a downstream stage. Note that configuration examples of the combustor 4 according to some embodiments will be described later.

[0014] A turbine 6 according to some embodiments includes a turbine casing 22 and various blades arranged in the turbine casing 22. The various blades include a plurality of stator vanes 24 fixed to the turbine casing 22 side and a plurality of moving blades 26 implanted in the rotor 8 so as to be arranged alternately with respect to the stator vanes 24. Note that the turbine 6 may also include other components such as outlet guide vanes. In the turbine 6, combustion gas passes through the plurality of stator vanes 24 and the plurality of moving blades 26, thereby driving the rotor 8 to rotate. This drives a generator connected to the rotor 8. An exhaust chamber 30 is connected to the downstream side of the turbine casing 22 via an exhaust casing 28. The combustion gases that have driven the turbine 6 are discharged to the outside via the exhaust casing 28 and the exhaust chamber 30.

[0015] (About Combustor 4) Fig. 2 is a cross-sectional view showing a combustor 4 according to some embodiments. Fig. 3 is a cross-sectional view showing a main part of the combustor 4 according to some embodiments. Fig. 4 is a diagram schematically showing an arrangement of each fuel injector in the combustor 4 according to some embodiments when viewed from the downstream side to the upstream side along the axial direction of the combustor 4. 2, 3 and 4, configurations of the combustor 4 according to some embodiments will be described.

[0016] 2 and 3, a plurality of combustors 4 according to some embodiments are arranged in an annular shape around the rotor 8 (see FIG. 1). Each combustor 4 includes a combustor liner 46 provided in a combustor casing 40 defined by a casing 20, and a main combustion burner 60 and a pilot combustion burner 50, which are fuel injectors respectively arranged in the combustor liner 46.

[0017] The combustor 4 further includes an outer casing 45 provided on the outer circumferential side of an inner casing 47 of the combustor liner 46 inside the casing 20. An air passage 43 through which compressed air flows is formed on the outer circumferential side of the inner casing 47 and on the inner circumferential side of the outer casing 45. The combustor 4 may include other components such as a bypass pipe (not shown) for bypassing the combustion gas.

[0018] For example, the combustor liner 46 has an inner cylinder 47 disposed around the pilot combustion burner 50 and the plurality of main combustion burners 60, and a transition piece 48 connected to the tip of the inner cylinder 47. In other words, the combustor liner 46 corresponds to a combustion section where the fuel F injected from the main combustion burners 60 and the pilot combustion burners 50 is combusted. 3 and 4, the pilot combustion burner 50 is disposed along the central axis of the combustor liner 46. A plurality of main combustion burners 60 are disposed spaced apart from one another and aligned in the circumferential direction so as to surround the outer periphery of the pilot combustion burner 50.

[0019] As shown in FIG. 3, the pilot combustion burner 50 has a pilot nozzle 54 connected to a fuel port 52, a pilot burner cylinder 56 arranged to surround the pilot nozzle 54, and a plurality of swirlers (swirl plates) 58 provided on the outer periphery of the pilot nozzle 54. The pilot nozzle 54 extends in an axial direction Da centered on the combustor axis Ac. Here, the upstream side along the flow of combustion gas on one side of the axial direction Da, which is the direction in which the combustor axis Ac extends, is referred to as the upstream side, and the downstream side along the flow of combustion gas on the other side is referred to as the downstream side. The combustor axis Ac is also the burner axis of this pilot combustion burner 50.

[0020] The downstream end of the pilot nozzle 54 is formed with an injection hole (not shown) for injecting fuel F. A plurality of swirl plates 58 are provided upstream of the pilot nozzle 54's injection hole. Each swirl plate 58 is used to swirl compressed air around the combustor axis Ac. Each swirl plate 58 extends from the outer periphery of the pilot nozzle 54 in a direction including a radial component and is located close to the inner circumferential surface of the pilot burner tube 56. The pilot burner tube 56 has a main body portion 56a located on the outer periphery of the pilot nozzle 54 and a cone portion 56b connected to the downstream side of the main body portion 56a and gradually expanding in diameter toward the downstream side. The plurality of swirl plates 58 are located close to the inner circumferential surface of the main body portion 56a of the pilot burner tube 56.

[0021] The pilot nozzle 54 suppresses the flame temperature to x The cone portion 56b has a water flow path (not shown) for suppressing the temperature rise and the metal temperature of the cone portion 56b, and is configured to be able to inject water.

[0022] The main combustion burner 60 has a main nozzle 64 connected to the fuel port 62, a main burner tube 66 arranged to surround the main nozzle 64, an extension pipe 65 connecting the main burner tube 66 to the combustor liner 46 (e.g., the inner tube 47), and a swirler (swirl plate) 70 provided on the outer periphery of the main nozzle 64.

[0023] The main nozzle 64 is a rod-shaped nozzle extending in an axial direction Da around a burner axis Ab that is parallel to the combustor axis Ac. Note that the burner axis Ab of the main combustion burner 60 is parallel to the combustor axis Ac, and therefore the axial direction Da relative to the combustor axis Ac and the axial direction Da relative to the burner axis Ab are the same direction. Furthermore, the upstream side of the axial direction Da relative to the combustor axis Ac is the upstream side of the axial direction Da relative to the burner axis Ab, and the downstream side of the axial direction Da relative to the combustor axis Ac is the downstream side of the axial direction Da relative to the burner axis Ab.

[0024] An injection hole for injecting fuel F is formed in the middle of the main nozzle 64 in the axial direction Da. A plurality of swirl plates 70 are provided near the positions where the injection holes are formed in the main nozzle 64. Each swirl plate 70 is used to swirl the compressed air around the burner axis Ab. Each swirl plate 70 extends in a direction including a radial component from the outer periphery of the main nozzle 64 and is close to the inner circumferential surface of the main burner cylinder 66. The main burner cylinder 66 is located on the outer periphery of the main nozzle 64.

[0025] In the combustor 4 having the above-described configuration, compressed air generated by the compressor 2 is supplied into the combustor casing 40 from the casing inlet 40a, and further flows from the combustor casing 40 through the air passage 43 into the pilot burner tube 56 and the plurality of main burner tubes 66.

[0026] In the pilot combustion burner 50, fuel F injected from a pilot nozzle 54 is ejected together with compressed air from the downstream end of a pilot burner tube 56. This fuel F undergoes diffusion combustion or premixed combustion within the combustor liner 46. That is, the pilot-fired burner 50 shown in Figures 2, 3 and 4 is a diffusion-fired or premixed-fired fuel injector.

[0027] In the main combustion burner 60, compressed air and fuel F injected from the main nozzle 64 are mixed in the main burner cylinder 66 to form premixed gas PM. In the main combustion burner 60, the premixed gas PM is injected from the downstream end of the extension pipe 65. The fuel F in this premixed gas PM is premixed and combusted in the combustor liner 46. That is, the main combustion burner 60 shown in FIGS. 2, 3 and 4 is a premixed combustion type fuel injector.

[0028] Alternatively, injection holes for injecting fuel F may be formed in the swivel plate 70, and the fuel F may be injected from these holes into the main burner cylinder 66. In this case, the portion corresponding to the rod-shaped main nozzle 64 described above forms a hub rod, and the main nozzle is formed by this hub rod and multiple swivel plates 70. Fuel F is supplied from the outside into the hub rod, and fuel F is supplied from this hub rod to the swivel plate 70.

[0029] (About fuel F) The combustor 4 according to some embodiments is configured to be able to use, for example, natural gas as in a conventional combustor, and also to use hydrogen as the fuel F. In the following description, natural gas as the fuel F will be referred to as natural gas fuel FN, or simply as natural gas. Similarly, in the following description, hydrogen as the fuel F will be referred to as hydrogen fuel FH, or simply as hydrogen. In the following description, natural gas fuel FN, hydrogen fuel FH, and mixed fuel FM of natural gas fuel FN and hydrogen fuel FH will be referred to as fuel F when there is no need to distinguish between them or when these fuels are referred to collectively.

[0030] (Fuel F supply system) Fig. 5 is a diagram showing an outline of a supply system 200 of fuel F to a combustor 4 according to some embodiments. A gas turbine 1 according to some embodiments includes the supply system 200 of fuel F shown in Fig. 5. The supply system 200 of fuel F shown in Fig. 5 includes a first supply line 211 for supplying natural gas fuel FN to the main combustion burner 60, a second supply line 212 for supplying natural gas fuel FN to the pilot combustion burner 50, a third supply line 221 for supplying hydrogen fuel FH to the main combustion burner 60 and the pilot combustion burner 50, and a fourth supply line 222 for supplying hydrogen fuel FH to the pilot combustion burner 50.

[0031] The natural gas fuel FN is supplied from a supply source 201 of the natural gas fuel FN via a natural gas supply line 210. The first supply line 211 and the second supply line 212 branch off at a branch point 231. The first supply line 211 is provided with a first control valve 241 for adjusting the amount of fuel F supplied to the main combustion burner 60. The downstream end of the first supply line 211 is connected to a fuel port 62 to which a main nozzle 64 of the main combustion burner 60 is connected. The second supply line 212 is provided with a second control valve 242 for adjusting the amount of fuel F supplied to the pilot combustion burner 50. The downstream end of the second supply line 212 is connected to a fuel port 52 to which a pilot nozzle 54 of the pilot combustion burner 50 is connected.

[0032] The hydrogen fuel FH is supplied from a supply source 202 of the hydrogen fuel FH via a hydrogen supply line 220. The third supply line 221 and the fourth supply line 222 branch off at a branch point 232. The third supply line 221 is provided with a third control valve 243 for adjusting the amount of hydrogen fuel FH supplied to the main combustion burner 60 and the pilot combustion burner 50. The downstream end of the third supply line 221 is connected to the natural gas supply line 210 at a junction 233 upstream of the branch point 231 in the natural gas supply line 210. That is, the third adjustment valve 243 is an adjustment valve for adjusting the amount of hydrogen fuel FH added to the natural gas fuel FN flowing through the natural gas supply line 210.

[0033] The fourth supply line 222 is provided with a fourth control valve 244 for adjusting the amount of hydrogen fuel FH supplied to the pilot combustion burner 50. The downstream end of the fourth supply line 222 is connected to the second supply line 212 at a junction 234 downstream of the second control valve 242 in the second supply line 212. That is, the fourth control valve 244 is a control valve that can adjust the amount of hydrogen fuel FH added to the natural gas fuel FN or the mixed fuel FM of natural gas fuel FN and hydrogen fuel FH flowing through the second supply line 212. As will be described later, by closing the second control valve 242 and opening the fourth control valve 244, only the hydrogen fuel FH can be supplied to the pilot combustion burner 50.

[0034] In the fuel F supply system 200 configured as described above, the hydrogen mixing ratio (calorie ratio), which is the ratio of hydrogen fuel FH in the fuel F injected in the main combustion burner 60 and the pilot combustion burner 50, can be adjusted by adjusting the opening degrees of the first control valve 241, the second control valve 242, the third control valve 243, and the fourth control valve 244. Control of the hydrogen mixing ratio in the combustor 4 according to some embodiments will be described in detail later.

[0035] The first control valve 241, the second control valve 242, the third control valve 243, and the fourth control valve 244 are controlled by a controller configured to be able to control each of these control valves. In some embodiments, the controller is realized by the combustion control device 140 of the gas turbine 1. Each processing function of the combustion control device 140 is configured by software (computer program) and executed by a computer, but is not limited to this and may be configured by hardware.

[0036] (Water supply) The gas turbine 1 according to some embodiments includes a water supply line 215 for supplying cooling water to the pilot combustion burner 50. Although a detailed description will be omitted, supplying cooling water suppresses the flame temperature that increases when the hydrogen mixed combustion ratio in the pilot combustion burner 50 is increased. x The occurrence of the heat is suppressed, and the metal temperature of the cone portion 56b of the pilot combustion burner 50 can be suppressed. Cooling water can be supplied to the pilot-fired burner 50 from a water supply 205 via a water supply line 215 . The water supply line 215 is provided with a water supply amount adjustment valve 251 for adjusting the amount of water supplied to the pilot combustion burner 50. Although a detailed description will be omitted, the water supply amount adjustment valve 251 is controlled by the combustion control device 140.

[0037] (Regarding hydrogen co-firing ratio control) For example, in facilities that emit carbon dioxide (CO2), a cause of global warming, such as gas turbines 1, there is a demand to reduce carbon dioxide emissions. For example, in order to reduce carbon dioxide emissions in gas turbines 1, it is desirable to increase the hydrogen co-firing ratio. However, because hydrogen has low ignition energy and a fast combustion speed, increasing the hydrogen co-firing ratio increases the possibility of flame backflow and other problems. On the other hand, the risk of flame backflow (flashback) differs depending on the structure of the fuel injector (combustion burner), the location of the fuel injector, etc., so the risk of flashback is not necessarily the same for all fuel injectors among multiple fuel injectors. Specifically, for example, as follows:

[0038] In the embodiment shown in Figures 2, 3 and 4, the main combustion burner 60 is a premixed combustion type fuel injector and the pilot combustion burner 50 is a diffusion or premixed combustion type fuel injector. Generally, a diffusion combustion type fuel injector has a lower risk of flashback than a premixed combustion type fuel injector. Therefore, in the embodiment shown in Figures 2, 3 and 4, the pilot combustion burner 50 is a fuel injector with a lower risk of flashback than the main combustion burner 60.

[0039] It should be noted that, in general, when a fuel injector is surrounded by other fuel injectors, the surrounded fuel injector has a lower risk of flashback than a surrounding fuel injector. 2, 3, and 4, a plurality of main combustion burners 60 are arranged around the pilot combustion burner 50. Therefore, if the main combustion burner 60 and the pilot combustion burner 50 have the same fuel injector structure, as in the case where both the main combustion burner 60 and the pilot combustion burner 50 are diffusion combustion or premix combustion fuel injectors in the embodiments shown in FIGS. 2, 3, and 4, the pilot combustion burner 50 will be a fuel injector with a lower risk of flashback than the main combustion burner 60.

[0040] Therefore, in a gas turbine operating method according to some embodiments, these factors are taken into consideration and the gas turbine 1 is operated as follows. As described above, the pilot combustion burner 50 is a fuel injector with a lower risk of flashback than the main combustion burner 60, so the upper limit Crpmax of the hydrogen mixing ratio Crp in the pilot combustion burner 50 is set to be larger than the upper limit Crmmax of the hydrogen mixing ratio Crm in the main combustion burner 60. This makes it possible to increase the maximum value Cromax of the hydrogen mixing ratio Cro in the entire combustor 4 while suppressing flashback. More specifically, in the combustor 4 according to some embodiments, the hydrogen mixing ratio is controlled as follows. The hydrogen mixing ratio Cro for the entire combustor 4 is the ratio of the total hydrogen fuel FH to the total fuel F injected from the multiple main combustion burners 60 and the pilot combustion burner 50 in one combustor, expressed in terms of calorie ratio.

[0041] FIG. 6A is a graph showing an example of the relationship between the hydrogen mixing ratios Crm and Crp of each combustion burner and the hydrogen mixing ratio Cro of the entire combustor 4 during rated operation. FIG. 6B is a graph showing an example of the relationship between the ratio (Crp / Crm) of the hydrogen mixing ratio Crp in the pilot combustion burner 50 to the hydrogen mixing ratio Crm in the main combustion burner 60 and the hydrogen mixing ratio Cro in the entire combustor 4, when the hydrogen mixing ratios Crm, Crp of each combustion burner and the hydrogen mixing ratio Cro in the entire combustor 4 have the relationship shown in FIG. 6A. FIG. 7A is a graph showing another example of the relationship between the hydrogen mixing ratios Crm and Crp of each combustion burner and the hydrogen mixing ratio Cro of the entire combustor 4 during rated operation. FIG. 7B is a graph showing an example of the relationship between the ratio (Crp / Crm) of the hydrogen mixing ratio Crp in the pilot combustion burner 50 to the hydrogen mixing ratio Crm in the main combustion burner 60 and the hydrogen mixing ratio Cro in the entire combustor 4, when the hydrogen mixing ratios Crm, Crp of each combustion burner and the hydrogen mixing ratio Cro in the entire combustor 4 have the relationship shown in FIG. 7A. FIG. 8A is a graph showing yet another example of the relationship between the hydrogen mixing ratios Crm and Crp of each combustion burner and the hydrogen mixing ratio Cro of the entire combustor 4 during rated operation. FIG. 8B is a graph showing an example of the relationship between the ratio (Crp / Crm) of the hydrogen mixing ratio Crp in the pilot combustion burner 50 to the hydrogen mixing ratio Crm in the main combustion burner 60 and the hydrogen mixing ratio Cro in the entire combustor 4, when the hydrogen mixing ratios Crm, Crp of each combustion burner and the hydrogen mixing ratio Cro in the entire combustor 4 have the relationship shown in FIG. 8A. FIG. 9A is a graph showing an example of the relationship between the hydrogen mixing ratios Crm and Crp of each combustion burner and the hydrogen mixing ratio Cro of the entire combustor 4 during partial load operation. FIG. 9B is a graph showing an example of the relationship between the ratio (Crp / Crm) of the hydrogen mixing ratio Crp in the pilot combustion burner 50 to the hydrogen mixing ratio Crm in the main combustion burner 60 and the hydrogen mixing ratio Cro in the entire combustor 4, when the hydrogen mixing ratios Crm, Crp of each combustion burner and the hydrogen mixing ratio Cro in the entire combustor 4 have the relationship shown in FIG. 9A.

[0042] For example, consider the case where, during rated operation of the gas turbine 1, the hydrogen co-firing ratio Cro is gradually increased from mono-combustion using natural gas fuel FN (hydrogen co-firing ratio Cro = 0%) to co-firing. In this case, as shown in FIG. 6A, during low-hydrogen-fuel-ratio operation in which the hydrogen-fuel-fuel ratio Cro of the entire combustor 4 is relatively low, the hydrogen-fuel-fuel ratios Crm and Crp of each combustion burner may be gradually increased while maintaining the same value as the hydrogen-fuel-fuel ratio Cro of the entire combustor 4 increases. Such changes in the hydrogen mixing ratios Crm and Crp of each combustion burner can be achieved, for example, by gradually opening the third control valve 243, which adjusts the amount of hydrogen fuel FH supplied to the main combustion burner 60 and the pilot combustion burner 50, while keeping the fourth control valve 244, which adjusts the amount of hydrogen fuel FH supplied to the pilot combustion burner 50 shown in Figure 5, closed. Furthermore, the combustion control device 140 may send a control signal to the third control valve 243 so that the third control valve 243 operates in this manner.

[0043] 6A, the hydrogen mixing ratios Crm and Crp of each combustion burner may be gradually increased while maintaining the same value, and then, after the hydrogen mixing ratio Crm of the main combustion burner 60 reaches the upper limit value Crmmax, the hydrogen mixing ratio Crp of the pilot combustion burner 50 may be gradually increased to increase the hydrogen mixing ratio Cro of the entire combustor 4. In other words, during high-hydrogen mixing ratio operation, in which the hydrogen mixing ratio is higher than during low-hydrogen mixing ratio operation, the hydrogen mixing ratio Crp of the pilot combustion burner 50 may be gradually increased to increase the hydrogen mixing ratio Cro of the entire combustor 4.

[0044] Such changes in the hydrogen mixing ratios Crm and Crp of each combustion burner can be achieved, for example, by gradually closing the second control valve 242 on the second supply line 212 and gradually opening the fourth control valve 244 while keeping the opening of the third control valve 243 shown in FIG. 5 fixed. Furthermore, the combustion control device 140 may send control signals to the second control valve 242 and the fourth control valve 244 so that the second control valve 242 and the fourth control valve 244 operate in this manner.

[0045] The upper limit Crpmax of the hydrogen mixing ratio Crp in the pilot combustion burner 50 may be 100% as shown in FIG. 6A and FIGS. 7A, 8A, and 9A, which will be described later.

[0046] For ease of explanation, the hydrogen mixing ratios Crm, Crp of each combustion burner are gradually increased while maintaining the same value, and then the hydrogen mixing ratio Crm of the main combustion burner 60 reaches the upper limit value Crmmax. This is followed by the value th1 of the hydrogen mixing ratio Cro of the entire combustor 4, or the value th3 described below. When the hydrogen mixing ratio Cro is equal to or less than the value th1 or th3, this will be referred to as low hydrogen mixing ratio operation, and when the hydrogen mixing ratio Cro exceeds the value th1 or th3, this will be referred to as high hydrogen mixing ratio operation.

[0047] As shown in FIG. 6A, when the hydrogen mixing ratios Crm and Crp of each combustion burner are changed, as shown in FIG. 6B, when the value of the hydrogen mixing ratio Cro is equal to or less than the value th1, the ratio (Crp / Crm) of the hydrogen mixing ratio Crp of the pilot combustion burner 50 to the hydrogen mixing ratio Crm of the main combustion burner 60 becomes 1. As shown in FIG. 6A, when the hydrogen mixing ratios Crm and Crp of each combustion burner are changed, as shown in FIG. 6B, when the value of the hydrogen mixing ratio Cro exceeds the value th1, the ratio (Crp / Crm) exceeds 1 and gradually increases as the hydrogen mixing ratio Cro increases.

[0048] In the following description, the ratio (Crp / Crm) during low hydrogen mixing ratio operation is referred to as a first ratio R1, and the ratio (Crp / Crm) during high hydrogen mixing ratio operation is referred to as a second ratio R2.

[0049] In the example shown in FIGS. 6A and 6B, in the process of increasing the hydrogen co-combustion rate Cro of the entire combustor 4, the fourth control valve 244 for adjusting the supply amount of the hydrogen fuel FH to the pilot combustion burner 50 was kept closed until the hydrogen co-combustion rate Crm in the main combustion burner 60 reached the upper limit value Crmmax. However, in the process of increasing the hydrogen co-combustion rate Cro of the entire combustor 4, the fourth control valve 244 may start to open before the hydrogen co-combustion rate Crm in the main combustion burner 60 reaches the upper limit value Crmmax. The example shown in FIGS. 7A and 7B is an example when the fourth control valve 244 starts to open when the hydrogen co-combustion rate Crm in the main combustion burner 60 reaches a value th2 (th2 < th1) smaller than the value th1 in the process of increasing the hydrogen co-combustion rate Cro of the entire combustor 4.

[0050] In the example shown in FIG. 7A, in the process of increasing the hydrogen co-combustion rate Cro of the entire combustor 4, until the hydrogen co-combustion rate Cro of the entire combustor 4 reaches the value th2, as the hydrogen co-combustion rate Cro of the entire combustor 4 increases, the hydrogen co-combustion rates Crm and Crp of each combustion burner gradually increase while taking the same value. In the example shown in FIG. 7A, after the hydrogen co-combustion rate Cro of the entire combustor 4 reaches the value th2 and until the hydrogen co-combustion rate Cro of the entire combustor 4 reaches the value th1, the hydrogen co-combustion rate Crp in the pilot combustion burner 50 takes a value larger than the hydrogen co-combustion rate Crm in the main combustion burner 60, and the difference between the two gradually increases as the hydrogen co-combustion rate Cro of the entire combustor 4 increases.

[0051] 7A, in the process of increasing the hydrogen mixing ratio Cro across the entire combustor 4, after the hydrogen mixing ratio Cro across the entire combustor 4 reaches a value th1, the hydrogen mixing ratio Crm in the main combustion burner 60 becomes an upper limit value Crmmax, and the hydrogen mixing ratio Crp in the pilot combustion burner 50 gradually increases. That is, in the example shown in FIG. 7A, in the process of increasing the hydrogen mixing ratio Cro across the entire combustor 4, after the hydrogen mixing ratio Cro across the entire combustor 4 reaches a value th1, for example, it is advisable to gradually close the second control valve 242 on the second supply line 212 and gradually open the fourth control valve 244 while keeping the aperture of the third control valve 243 shown in FIG. 5 fixed.

[0052] As shown in FIG. 7A, when the hydrogen mixing ratios Crm and Crp of each combustion burner are changed, as shown in FIG. 7B, when the value of the hydrogen mixing ratio Cro is equal to or less than the value th2, the ratio (Crp / Crm) of the hydrogen mixing ratio Crp of the pilot combustion burner 50 to the hydrogen mixing ratio Crm of the main combustion burner 60 becomes 1. As shown in FIG. 7A, when the hydrogen mixing ratios Crm and Crp of each combustion burner are changed, as shown in FIG. 7B, when the hydrogen mixing ratio Cro exceeds the value th2, the ratio (Crp / Crm) exceeds 1 and gradually increases as the hydrogen mixing ratio Cro increases.

[0053] 7A and 7B, in the process of increasing the hydrogen mixing ratio Cro throughout the entire combustor 4, the fourth control valve 244 for adjusting the supply amount of hydrogen fuel FH to the pilot combustion burner 50 is kept closed until the hydrogen mixing ratio Cro throughout the entire combustor 4 reaches the value th2. However, in the process of increasing the hydrogen mixing ratio Cro throughout the entire combustor 4, the fourth control valve 244 may be started to open at the same time as the third control valve 243 is started to open. The example shown in Figures 8A and 8B is an example of a case where the third control valve 243 starts to be opened and the fourth control valve 244 starts to be opened at the same time in the process of increasing the hydrogen mixing ratio Cro in the entire combustor 4.

[0054] In the example shown in FIG. 8A, in the process of increasing the hydrogen mixing ratio Cro of the entire combustor 4, the hydrogen mixing ratio Crp of the pilot combustion burner 50 is greater than the hydrogen mixing ratio Crm of the main combustion burner 60 until the hydrogen mixing ratio Cro of the entire combustor 4 reaches the value th1. As the hydrogen mixing ratio Cro of the entire combustor 4 increases, the difference between the two gradually increases.

[0055] 8A, in the process of increasing the hydrogen mixing ratio Cro across the entire combustor 4, after the hydrogen mixing ratio Cro across the entire combustor 4 reaches a value th1, the hydrogen mixing ratio Crm in the main combustion burner 60 becomes an upper limit value Crmmax, and the hydrogen mixing ratio Crp in the pilot combustion burner 50 gradually increases. That is, in the example shown in FIG. 8A, in the process of increasing the hydrogen mixing ratio Cro across the entire combustor 4, after the hydrogen mixing ratio Cro across the entire combustor 4 reaches a value th1, for example, it is advisable to gradually close the second control valve 242 on the second supply line 212 and gradually open the fourth control valve 244 while keeping the aperture of the third control valve 243 shown in FIG. 5 fixed.

[0056] As shown in FIG. 8A, when the hydrogen mixing ratios Crm, Crp of each combustion burner are changed, the ratio (Crp / Crm) of the hydrogen mixing ratio Crp of the pilot combustion burner 50 to the hydrogen mixing ratio Crm of the main combustion burner 60 exceeds 1 and gradually increases as the hydrogen mixing ratio Cro of the entire combustor 4 increases, as shown in FIG. 8B.

[0057] (When operating at partial load) Generally, the higher the load on the gas turbine 1, the greater the supply of fuel F, and therefore the greater the risk of flashback. Conversely, the risk of hydrogen fuel flashback is smaller during partial load operation of the gas turbine 1 than during rated operation, so the maximum value Cromax of the hydrogen mixing ratio Cro throughout the combustor 4 during partial load operation can be made greater than during rated operation. As described above, the upper limit Crpmax of the hydrogen mixing ratio Crp in the pilot combustion burner 50 is 100% during rated operation as shown in FIGS. 6A, 7A, and 8A, so there is no room to raise the upper limit Crpmax of the hydrogen mixing ratio Crp in the pilot combustion burner 50. Therefore, in a gas turbine operation method according to some embodiments, as shown in FIGS. 9A and 9B , the upper limit value Crmmax of the hydrogen mixing ratio Crm in the main combustion burner 60 during partial load operation is set to be larger than that during rated operation, thereby making the maximum value Cromax of the hydrogen mixing ratio Cro in the entire combustor 4 during partial load operation larger than that during rated operation.

[0058] That is, in the gas turbine operation method according to some embodiments, as is clear from a comparison of FIG. 9A with, for example, FIG. 6A, the upper limit value Crmmax of the hydrogen mixing ratio Crm in the main combustion burner 60 during partial load operation is made larger than that during rated operation.

[0059] For example, consider the case where the gas turbine 1 is operating at a partial load and the hydrogen co-firing rate Cro is gradually increased from mono-fuel combustion using natural gas fuel FN (hydrogen co-firing rate Cro = 0%). In this case, as shown in FIG. 9A, during low-hydrogen-fuel-ratio operation in which the hydrogen-fuel-fuel ratio Cro of the entire combustor 4 is relatively low, the hydrogen-fuel-fuel ratios Crm and Crp of each combustion burner may be set to gradually increase while maintaining the same value as the hydrogen-fuel-fuel ratio Cro of the entire combustor 4 increases.

[0060] 9A, the hydrogen mixing ratios Crm and Crp of each combustion burner may be gradually increased while maintaining the same value, and then, after the hydrogen mixing ratio Crm of the main combustion burner 60 reaches the upper limit value Crmmax, the hydrogen mixing ratio Crp of the pilot combustion burner 50 may be gradually increased to increase the hydrogen mixing ratio Cro of the entire combustor 4. In other words, during high-hydrogen mixing ratio operation, in which the hydrogen mixing ratio is higher than during low-hydrogen mixing ratio operation, the hydrogen mixing ratio Crp of the pilot combustion burner 50 may be gradually increased to increase the hydrogen mixing ratio Cro of the entire combustor 4. In the example shown in FIG. 9A, in the process of increasing the hydrogen mixing ratio Cro throughout the entire combustor 4, after the hydrogen mixing ratio Cro throughout the entire combustor 4 reaches the value th3, for example, while keeping the aperture of the third control valve 243 shown in FIG. 5 fixed, the second control valve 242 on the second supply line 212 may be gradually closed and the fourth control valve 244 may be gradually opened.

[0061] As shown in FIG. 9A, when the hydrogen mixing ratios Crm and Crp of each combustion burner are changed, as shown in FIG. 9B, when the value of the hydrogen mixing ratio Cro is equal to or less than the value th3 (during low hydrogen mixing ratio operation), the ratio (Crp / Crm) of the hydrogen mixing ratio Crp of the pilot combustion burner 50 to the hydrogen mixing ratio Crm of the main combustion burner 60 becomes 1. As shown in FIG. 9A, when the hydrogen mixing ratios Crm and Crp of each combustion burner are changed, as shown in FIG. 9B, when the hydrogen mixing ratio Cro exceeds the value th3 (during high hydrogen mixing ratio operation), the ratio (Crp / Crm) exceeds 1 and gradually increases as the hydrogen mixing ratio Cro increases. The upper limit Crmmax of the hydrogen mixing ratio Crm in the main combustion burner 60 may be set to increase as the combustion gas temperature T1T at the inlet of the gas turbine decreases.

[0062] Summary of Methods of Operating a Gas Turbine According to Some Embodiments The contents of the above-described embodiments are summarized below. According to some embodiments, a method for operating a gas turbine is provided for operating a gas turbine 1 including a combustor 4 having a main nozzle 64 and a pilot nozzle 54, and capable of using hydrogen and a fuel other than hydrogen as fuel. As shown in Figures 6B, 7B, 8B, and 9B, the ratio (Crp / Crm) of the hydrogen mixing ratio Crp of the fuel F injected from the pilot nozzle 54 to the hydrogen mixing ratio Crm of the fuel F injected from the main nozzle 64 is greater than the first ratio R1 during low hydrogen mixing ratio operation in a second ratio R2 during high hydrogen mixing ratio operation in which the hydrogen mixing ratio Cro of the entire combustor 4 is higher than that during low hydrogen mixing ratio operation.

[0063] For example, if the pilot combustion burner 50 is less likely to cause flame backflow than the main combustion burner 60, when the hydrogen mixing ratio Cro of the entire combustor 4 is increased, the risk of backfire can be reduced by making the hydrogen mixing ratio Crp of the fuel F injected from the pilot combustion burner 50 higher than the hydrogen mixing ratio Crm of the fuel F injected from the main combustion burner 60. According to the gas turbine operating method of some embodiments, when the pilot combustion burner 50 is less likely to cause flashback than the main combustion burner 60, the gas turbine can be operated at a high hydrogen mixing ratio Cro while suppressing flashback.

[0064] In the gas turbine operation method according to some embodiments, as shown in FIGS. 6B, 7B, 8B, and 9B, the second ratio R2 may increase as the hydrogen mixing ratio of the fuel F supplied to the combustor 4 (the hydrogen mixing ratio Cro in the entire combustor 4) increases. As a result, during high hydrogen mixing ratio operation, the hydrogen mixing ratio Crm of the main combustion burner 60 is suppressed to suppress flashback, while the hydrogen mixing ratio Crp of the pilot combustion burner 50 is increased, thereby making it possible to increase the hydrogen mixing ratio Cro of the entire combustor 4.

[0065] In a gas turbine operating method according to some embodiments, as shown in FIGS. 6A , 7A , 8A , and 9A , during high-hydrogen-mixture-ratio operation, the hydrogen-mixture-ratio Crp of the fuel F injected from the pilot combustion burner 50 increases as the hydrogen-mixture-ratio of the fuel F supplied to the combustor 4 (the hydrogen-mixture-ratio Cro of the entire combustor 4) increases. As a result, during high hydrogen mixing ratio operation, by increasing the hydrogen mixing ratio Crp of the pilot combustion burner 50, it is possible to increase the hydrogen mixing ratio Cro of the entire combustor 4 while suppressing flashback.

[0066] In a method of operating a gas turbine according to some embodiments, as shown in FIGS. 6A , 7A , 8A , and 9A , during high-hydrogen-fuel-mixture operation, the rate of increase in the hydrogen-fuel mixing ratio Crp of the fuel F injected from the pilot combustion burner 50 relative to the rate of increase in the hydrogen-fuel mixing ratio of the fuel F supplied to the combustor 4 (the hydrogen-fuel mixing ratio Cro of the entire combustor 4) may be greater than the rate of increase in the hydrogen-fuel mixing ratio Crm of the fuel F injected from the main combustion burner 60 relative to the rate of increase in the hydrogen-fuel mixing ratio of the fuel F supplied to the combustor 4 (the hydrogen-fuel mixing ratio Cro of the entire combustor 4). Note that the fact that the rate of increase in the hydrogen mixing ratio Crp relative to the rate of increase in the hydrogen mixing ratio Cro is greater than the rate of increase in the hydrogen mixing ratio Crm relative to the rate of increase in the hydrogen mixing ratio Cro is equivalent to the slope of the graph line for the hydrogen mixing ratio Crp being greater than the slope of the graph line for the hydrogen mixing ratio Crm in Figures 6A, 7A, 8A, and 9A. In the gas turbine operation methods according to some embodiments, as shown in FIGS. 6A, 7A, 8A, and 9A, during high hydrogen mixing ratio operation, i.e., when the value of the hydrogen mixing ratio Cro exceeds the value th1 or th3, the slope of the graph line for the hydrogen mixing ratio Crp is larger than the slope of the graph line for the hydrogen mixing ratio Crm. As a result, during high hydrogen mixing ratio operation, the hydrogen mixing ratio Crm of the main combustion burner 60 is suppressed to suppress flashback, while the hydrogen mixing ratio Crp of the pilot combustion burner 50 is increased, thereby making it possible to increase the hydrogen mixing ratio Cro of the entire combustor 4.

[0067] In a gas turbine operation method according to some embodiments, as shown in FIGS. 6A , 7A , 8A , and 9A , during high-hydrogen-mixture-ratio operation, the hydrogen-mixture ratio Crm of the fuel F injected from the main combustion burner 60 may be a constant value regardless of the hydrogen-mixture ratio of the fuel F supplied to the combustor 4 (the hydrogen-mixture ratio Cro of the entire combustor 4). As a result, during high hydrogen mixing ratio operation, the hydrogen mixing ratio Crm of the main combustion burner 60 is kept constant to suppress flashback, while the hydrogen mixing ratio Crp of the pilot combustion burner 50 is increased, thereby making it possible to increase the hydrogen mixing ratio Cro of the entire combustor 4.

[0068] In the gas turbine operation method according to some embodiments, as shown in FIGS. 6A, 7A, 8A, and 9A, the upper limit value Crpmax of the hydrogen mixing ratio Crp of the fuel F injected from the pilot combustion burner 50 may be 100%. This makes it possible to make the hydrogen mixing ratio Crp of the pilot combustion burner 50 100% while suppressing flashback in the combustor 4, and to increase the hydrogen mixing ratio Cor of the entire combustor 4.

[0069] In the gas turbine operating method according to some embodiments, as shown in FIGS. 6A, 7A, and 9A, the first ratio R1 may be 1 during at least a portion of the low hydrogen mixing ratio operation. As a result, the hydrogen mixing ratio Crm of the fuel F injected from the main combustion burner 60 and the hydrogen mixing ratio Crp of the fuel F injected from the pilot combustion burner 50 are equal, so that the supply system 200 for the fuel F to the main combustion burner 60 and the pilot combustion burner 50 can be shared as shown in FIG. 5, thereby simplifying the supply system 200 for the fuel F.

[0070] In a gas turbine operation method according to some embodiments, as shown in FIGS. 6A and 9A , the upper limit value Crmmax of the hydrogen mixing ratio Crm of the fuel F injected from the main combustion burner 60 may be larger during partial load operation of the gas turbine 1 than during rated operation.

[0071] Because the risk of backfire of hydrogen fuel FH is smaller during partial load operation of the gas turbine 1 than during rated operation, the maximum value Cromax of the hydrogen mixing ratio Cro across the entire combustor 4 during partial load operation can be made larger than that during rated operation. According to the gas turbine operation method according to some embodiments, by making the upper limit Crmmax of the hydrogen mixing ratio Crm of the main combustion burner 60 during partial load operation larger than that during rated operation, the maximum value Cromax of the total hydrogen mixing ratio (hydrogen mixing ratio Cro across the entire combustor 4) during partial load operation can be made larger than that during rated operation. Furthermore, according to the gas turbine operation method of some embodiments, even when the hydrogen mixing ratio Crp in the pilot combustion burner 50 reaches 100% and the hydrogen mixing ratio Crp in the pilot combustion burner 50 cannot be increased any further, the hydrogen mixing ratio Cro in the entire combustor 4 can be increased.

[0072] In a method of operating a gas turbine according to some embodiments, as shown in Figures 2, 3, and 4, the combustor 4 may include a main combustion burner 60 having a main nozzle 64 and a pilot combustion burner 50 having a pilot nozzle 54. The main combustion burner 60 may be a premixed combustion burner, and the pilot combustion burner 50 may be a diffusion combustion burner. As a result, the risk of backfire is lower with a diffusion combustion burner than with a premixed combustion burner, so the upper limit of the hydrogen mixing ratio Crp of the pilot combustion burner 50 can be increased, and the total hydrogen mixing ratio (hydrogen mixing ratio Cro in the entire combustor 4) can be increased.

[0073] In the method for operating a gas turbine according to some embodiments, the pilot combustion burner 50 may have a water flow path and be configured to be able to inject water. This suppresses the flame temperature and reduces NO x and the metal temperature of the pilot combustion burner 50 (cone portion 56b).

[0074] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications. For example, in the gas turbine operation method according to some of the above-described embodiments, in at least a part of the range of the hydrogen mixing ratio Cro where the value of the hydrogen mixing ratio Cro is equal to or less than the value th1 or th3, the ratio (Crp / Crm) of the hydrogen mixing ratio Crp in the pilot combustion burner 50 to the hydrogen mixing ratio Crm in the main combustion burner 60 may be less than 1.

[0075] The contents described in each of the above embodiments can be understood, for example, as follows. (1) A method of operating a gas turbine 1 according to at least one embodiment of the present disclosure is a method of operating a gas turbine 1 including a combustor 4 having a main nozzle 64 and a pilot nozzle 54, and capable of using hydrogen and a fuel other than hydrogen as fuel. The ratio (Crp / Crm) of the hydrogen mixing ratio (Crp) of the fuel F injected from the pilot nozzle 54 to the hydrogen mixing ratio (Crm) of the fuel F injected from the main nozzle 64 is greater at a second ratio R2 during high hydrogen mixing ratio operation, in which the hydrogen mixing ratio (Cro) is higher than at a low hydrogen mixing ratio operation, than at a first ratio R1 during low hydrogen mixing ratio operation.

[0076] For example, if the pilot nozzle 54 is less likely to cause flashback than the main nozzle 64, when increasing the hydrogen mixing ratio Cro throughout the combustor 4, the risk of flashback can be reduced by making the hydrogen mixing ratio (Crp) of the fuel F injected from the pilot nozzle 54 higher than the hydrogen mixing ratio (Crm) of the fuel F injected from the main nozzle 64. According to the method (1) above, if the pilot nozzle 54 is less likely to cause flame backflow than the main nozzle 64, operation at a high hydrogen co-firing ratio (Cro) can be achieved while suppressing backfire.

[0077] (2) In some embodiments, in the method (1) above, the second ratio R2 may be increased as the hydrogen mixing ratio (Cro) of the fuel F supplied to the combustor 4 increases.

[0078] According to the method (2) described above, during high-hydrogen-mixed-combustion-ratio operation, the hydrogen mixing ratio (Crm) of the main nozzle 64 is suppressed to suppress flashback, while the hydrogen mixing ratio (Crp) of the pilot nozzle 54 is increased, thereby making it possible to increase the hydrogen mixing ratio Cro of the entire combustor 4.

[0079] (3) In some embodiments, in the method described in (2) above, during high hydrogen mixing ratio operation, the hydrogen mixing ratio (Crp) of the fuel F injected from the pilot nozzle 54 may be increased as the hydrogen mixing ratio (Cro) of the fuel F supplied to the combustor 4 increases.

[0080] According to the method (3) above, during high-hydrogen-mixed-fuel-ratio operation, the hydrogen-mixed-fuel ratio (Crp) of the pilot nozzle 54 can be increased to increase the hydrogen-mixed-fuel ratio Cro in the entire combustor 4 while suppressing flashback.

[0081] (4) In some embodiments, in the method of (2) or (3) above, during high hydrogen mixing ratio operation, the rate of increase in the hydrogen mixing ratio (Crp) of the fuel F injected from the pilot nozzle 54 relative to the rate of increase in the hydrogen mixing ratio (Cro) of the fuel F supplied to the combustor 4 may be greater than the rate of increase in the hydrogen mixing ratio (Crm) of the fuel F injected from the main nozzle 64 relative to the rate of increase in the hydrogen mixing ratio (Cro) of the fuel F supplied to the combustor 4.

[0082] According to the method (4) above, during high-hydrogen-mixed-combustion-ratio operation, the hydrogen mixing ratio (Crm) of the main nozzle 64 is suppressed to suppress flashback, while the hydrogen mixing ratio (Crp) of the pilot nozzle 54 is increased, thereby making it possible to increase the hydrogen mixing ratio Cro of the entire combustor 4.

[0083] (5) In some embodiments, in the method of (4) above, during high hydrogen mixing ratio operation, the hydrogen mixing ratio (Crm) of the fuel F injected from the main nozzle 64 may be a constant value regardless of the hydrogen mixing ratio (Cro) of the fuel F supplied to the combustor 4.

[0084] According to the method (5) above, during high-hydrogen-mixed-combustion-ratio operation, the hydrogen mixing ratio (Cro) of the entire combustor 4 can be increased by increasing the hydrogen mixing ratio (Crp) of the pilot nozzle 54 while keeping the hydrogen mixing ratio (Crm) of the main nozzle 64 constant to suppress flashback.

[0085] (6) In some embodiments, in any of the methods (1) to (5) above, the upper limit of the hydrogen mixture ratio (Crp) of the fuel F injected from the pilot nozzle 54 may be 100%.

[0086] According to the method (6) above, the hydrogen mixing ratio (Crp) of the pilot nozzle 54 can be set to 100% while suppressing flashback in the combustor 4, and the hydrogen mixing ratio Cro of the entire combustor 4 can be increased.

[0087] (7) In some embodiments, in any of the methods (1) to (6) above, the first ratio R1 may be 1 during at least a portion of the low hydrogen mixing ratio operation.

[0088] According to the method (7) above, the hydrogen mixing ratio (Crm) of the fuel F injected from the main nozzle 64 is equal to the hydrogen mixing ratio (Crp) of the fuel F injected from the pilot nozzle 54. Therefore, the supply system 200 for the fuel F to the main nozzle 64 and the pilot nozzle 54 can be shared, and therefore the supply system 200 for the fuel F can be simplified.

[0089] (8) In some embodiments, in any of the methods (1) to (7) above, the upper limit (Crmmax) of the hydrogen mixing ratio (Crm) of the fuel F injected from the main nozzle 64 may be greater during partial load operation of the gas turbine 1 than during rated operation.

[0090] Because the risk of backfiring of hydrogen fuel FH is smaller during partial load operation of the gas turbine 1 than during rated operation, the maximum value Cromax of the hydrogen mixing ratio Cro for the entire combustor 4 during partial load operation can be made larger than during rated operation. According to the method (8) above, by making the upper limit (Crmmax) of the hydrogen mixing ratio (Crm) of the main nozzle 64 during partial load operation larger than during rated operation, the maximum value (Cromax) of the total hydrogen mixing ratio (Cro) during partial load operation can be made larger than during rated operation.

[0091] (9) In some embodiments, in any of the methods (1) to (8) above, the combustor 4 may include a main combustion burner 60 having a main nozzle 64 and a pilot combustion burner 50 having a pilot nozzle 54. The main combustion burner 60 may be a premixed combustion type burner, and the pilot combustion burner 50 may be a diffusion combustion type burner.

[0092] According to the method (9) above, since the risk of flashback is smaller with a diffusion combustion burner than with a premixed combustion burner, the upper limit (Crpmax) of the hydrogen mixing ratio (Crp) of the pilot combustion burner 50 can be increased, and the total hydrogen mixing ratio (Cro) can be increased.

[0093] (10) In some embodiments, in any of the methods (1) to (9) above, the pilot nozzle 54 may have a water flow path and be configured to be able to inject water.

[0094] According to the method (10) above, the flame temperature is suppressed and NO x and the metal temperature of the pilot combustion burner 50 (cone portion 56b). [Explanation of symbols]

[0095] 1. Gas turbine 4 Gas turbine combustor (combustor) 50 Pilot combustion burner 54 Pilot nozzle 60 Main combustion burner 64 Main nozzle 200 Supply system

Claims

1. A method for operating a gas turbine having a combustor that has a main nozzle and a pilot nozzle and that can use hydrogen and a fuel other than hydrogen as fuel, comprising the steps of: The ratio of the hydrogen mixing ratio of the fuel injected from the pilot nozzle to the hydrogen mixing ratio of the fuel injected from the main nozzle is a second ratio during high hydrogen mixing ratio operation in which the hydrogen mixing ratio is higher than that during low hydrogen mixing ratio operation, which is larger than a first ratio during low hydrogen mixing ratio operation. How to operate a gas turbine.

2. The second ratio increases as the hydrogen-mixed combustion ratio of the fuel supplied to the combustor increases. The method for operating a gas turbine according to claim 1 .

3. During the high hydrogen mixing ratio operation, the hydrogen mixing ratio of the fuel injected from the pilot nozzle increases as the hydrogen mixing ratio of the fuel supplied to the combustor increases. The method for operating a gas turbine according to claim 2.

4. during the high hydrogen mixing ratio operation, an increase rate of the hydrogen mixing ratio of the fuel injected from the pilot nozzle relative to an increase rate of the hydrogen mixing ratio of the fuel supplied to the combustor is larger than an increase rate of the hydrogen mixing ratio of the fuel injected from the main nozzle relative to an increase rate of the hydrogen mixing ratio of the fuel supplied to the combustor. The method for operating a gas turbine according to claim 2 or 3.

5. During the high hydrogen mixing ratio operation, the hydrogen mixing ratio of the fuel injected from the main nozzle is a constant value regardless of the hydrogen mixing ratio of the fuel supplied to the combustor. The method for operating a gas turbine according to claim 4.

6. The upper limit of the hydrogen mixing ratio of the fuel injected from the pilot nozzle is 100%. The method for operating a gas turbine according to claim 1 or 2.

7. During at least a portion of the low hydrogen mixing ratio operation, the first ratio is 1. The method for operating a gas turbine according to claim 1 or 2.

8. an upper limit of the hydrogen mixing ratio of the fuel injected from the main nozzle is higher during partial load operation of the gas turbine than during rated operation. The method for operating a gas turbine according to claim 1 or 2.

9. the combustor includes a main combustion burner having the main nozzle and a pilot combustion burner having the pilot nozzle; the main combustion burner is a premixed combustion type burner, The pilot combustion burner is a diffusion combustion type burner. The method for operating a gas turbine according to claim 1 or 2.

10. The pilot nozzle has a water flow path and is configured to be able to inject the water. The method for operating a gas turbine according to claim 1 or 2.

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