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

Abstract

To prevent erroneous detection of flashback.SOLUTION: A gas turbine control device is targeted for control of a gas turbine that comprises a combustor capable of mixing and burning a first fuel and a second fuel with combustion air, a bypass passage capable of bypassing and supplying at least a part of combustion air to a downstream side space of the combustor, and a bypass valve provided in the bypass passage. The gas turbine control device performs control so as to increase a mixed combustion rate of the second fuel as the load of a gas turbine increases, and controls an opening of the bypass valve on the basis of the mixed combustion rate. The opening control of the bypass valve is performed so as to control the opening of the bypass valve so that the bypass valve is fully closed in a second load smaller than a first load in which the bypass valve is fully closed when the opening is reduced in inverse proportion to the load of the gas turbine.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a gas turbine control device, a gas turbine control method, and a gas turbine modification method. [Background technology]

[0002] For example, in a thermal power plant, a gas turbine driven by combustion gas generated by burning fuel is used as a turbine for driving a generator. This type of gas turbine is equipped with a combustor for burning fuel, and the amount of fuel supplied to the combustor is variably controlled according to the load of the gas turbine. For example, when the load of the gas turbine is low, the amount of fuel supplied to the combustor is small, so that the ratio of fuel to combustion air in the combustion region (fuel-air ratio) decreases, and the combustion efficiency is likely to deteriorate.

[0003] To address this issue, in Patent Document 1, during low-load operation of the gas turbine, part of the combustion air supplied to the combustor is bypassed to the downstream space of the combustor via a bypass valve, thereby maintaining a high fuel-air ratio, thereby ensuring flame stability and improving combustion efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-124338 A Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, thermal power plants have been considering ways to improve power generation efficiency and actively use fuels other than fossil fuels, such as hydrogen, as a means of reducing carbon dioxide (CO2) emissions, which are a cause of global warming. In order to reduce carbon dioxide emissions, it is desirable to increase the mixed combustion ratio of the second fuel (hydrogen), which has a relatively low calorific value per unit volume, compared to the first fuel, such as natural gas. However, because hydrogen has a low ignition energy and a fast combustion speed, increasing the mixed combustion ratio of hydrogen increases the possibility of flashbacks (reverse flow of flames) and other problems.

[0006] Flashbacks occurring in gas turbines can be detected from trend changes in the blade passage temperature (BPT), which is the temperature of the combustion gas that passes through the turbine. The blade passage temperature is measured by a temperature sensor, such as a thermocouple, installed downstream of the combustor.

[0007] Here, as in Patent Document 1, when the load of the gas turbine is relatively low, if a part of the combustion air is bypassed to the space downstream of the combustor via a bypass valve, the inflow state in the space downstream of the combustor changes, causing the heat distribution in the space (particularly the position of the hot spot where the temperature becomes high) to fluctuate. This affects the results of the measurement of the blade path temperature by the temperature sensor installed as described above, and there is a risk of erroneously detecting the occurrence of flashback based on the results of the measurement of the blade path temperature.

[0008] At least one embodiment of the present disclosure has been made in consideration of the above-mentioned circumstances, and an object of the present disclosure is to provide a gas turbine control device, a gas turbine control method, and a gas turbine modification method that are capable of preventing erroneous detection of flashback. [Means for solving the problem]

[0009] In order to solve the above problems, a gas turbine control device according to at least one embodiment of the present disclosure includes: a combustor capable of mixing a mixed fuel containing a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel with combustion air and combusting the mixed fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; A gas turbine control device for controlling a gas turbine comprising: a mixed-combustion ratio control unit that controls the mixed-combustion ratio of the second fuel to be increased as the load of the gas turbine increases; a bypass valve control unit for controlling an opening degree of the bypass valve based on the mixed combustion ratio; Equipped with The bypass valve control unit controls the bypass valve to a fully closed state when the mixed combustion ratio is greater than a first threshold value.

[0010] In order to solve the above problem, a gas turbine control method according to at least one embodiment of the present disclosure includes: a combustor capable of mixing a mixed fuel containing a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel with combustion air and combusting the mixed fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; 1. A gas turbine control method for controlling a gas turbine comprising: controlling a mixed combustion ratio of the second fuel to be increased as a load of the gas turbine increases; controlling an opening degree of the bypass valve based on the mixed combustion ratio; Equipped with In the step of controlling the bypass valve, when the mixed combustion ratio is greater than a first threshold value, the bypass valve is controlled to a fully closed state.

[0011] In order to solve the above problems, a gas turbine modification method according to at least one embodiment of the present disclosure includes the following steps: a combustor capable of mixing a first fuel with combustion air and combusting the first fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; Equipped with A gas turbine modification method for modifying a gas turbine capable of implementing a dedicated combustion operation mode in which an opening degree of the bypass valve is controlled based on a load of the gas turbine, the method comprising the steps of: A mixed fuel containing the first fuel and a second fuel having a lower heat value per unit volume than the first fuel is mixed with the combustion air in the combustor and combusted, and when a mixed combustion ratio of the second fuel is greater than a first threshold value, a mixed combustion operation mode in which the bypass valve is controlled to a fully closed state is modified to be switchable to the mono-fuel operation mode. Effect of the Invention

[0012] According to at least one embodiment of the present disclosure, it is possible to provide a gas turbine control device, a gas turbine control method, and a gas turbine revamping method that are capable of preventing erroneous detection of a flashback. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a gas turbine according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing a simplified internal configuration of the combustor shown in FIG. [Diagram 3] FIG. 2 is a block diagram showing a functional configuration of a gas turbine control device according to an embodiment. [Figure 4] 4 is a graph showing the relationship between the bypass valve opening degree and the mixed combustion ratio, and the load of the gas turbine, in the reference technology controlled by the bypass valve opening degree control unit in FIG. 3. [Diagram 5] FIG. 3 is a perspective view diagrammatically illustrating the combustor shown in FIG. 2. [Figure 6] FIG. 6 is a cross-sectional view showing a hot spot at cross section B of FIG. 5. [Figure 7A]4 is a graph showing a relationship between the opening degree of the bypass valve, the mixed combustion ratio, and the load of the gas turbine in an embodiment controlled by the bypass valve opening control unit in FIG. 3. [Figure 7B] 4 is a graph showing the relationship between the bypass valve opening degree and the mixed combustion ratio, and the load of the gas turbine, in another embodiment controlled by the bypass valve opening degree control unit in FIG. 3. [Figure 8] 2 is a diagram showing an arrangement layout of main fuel injection nozzles among a plurality of fuel injection nozzles included in the combustor shown in FIG. 1, viewed from the downstream side. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the configurations described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.

[0015] First, a gas turbine 1 that is a control target of a gas turbine control device 100 according to at least one embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a diagram showing a schematic configuration of the gas turbine 1 according to one embodiment, and Fig. 2 is a cross-sectional view simply showing an internal configuration of a combustor 2 in Fig. 1.

[0016] The gas turbine 1 includes a compressor 3 for generating compressed air (hereinafter, appropriately referred to as "combustion air A"), a combustor 2 for generating combustion gas by mixing and burning the combustion air generated by the compressor 3 with fuel, a fuel supply system 4 for supplying fuel to the combustor 2, and a turbine 6 that can be driven by the combustion gas. The compressor 3 and the turbine 6 are connected to one shaft. In the gas turbine 1 having such a configuration, the combustion air A from the compressor 3 and fuel (mixed fuel Fm described below) supplied from the fuel supply system 4 are supplied to the combustor 2, and these are mixed and combusted to generate combustion gas. This combustion gas flows into the turbine 6 and functions as a working medium for driving the turbine 6.

[0017] The fuel supply system 4 handles a mixed fuel obtained by mixing a first fuel F1 and a second fuel F2 as the fuel to be supplied to the combustor 2. The second fuel F2 is a fuel having a lower calorific value per unit volume than the first fuel F1. In this embodiment, the first fuel F1 is liquefied natural gas (LNG), and the second fuel F2 is hydrogen gas.

[0018] The first fuel F1 is stored in a first fuel supply source 7, and is supplied via a first fuel supply line 8 connected to the first fuel supply source 7. A flow meter 10 for detecting the flow rate of the first fuel F1 is provided in the first fuel supply line 8.

[0019] The second fuel F2 is stored in a second fuel supply source 14, and is supplied via a second fuel supply line 16 connected to the second fuel supply source 14. The second fuel supply line 16 is provided with a first flow rate adjustment valve 18 for adjusting the flow rate of the second fuel F2, a shutoff valve 13 for shutting off the second fuel F2, and a flow meter 15 for detecting the flow rate of the second fuel F2.

[0020] The first fuel supply line 8 and the second fuel supply line 16 join each other at a joining point 25 provided downstream and are connected to a main fuel supply line 22. The first fuel F1 and the second fuel F2 join at the joining point 25 to form a mixed fuel (hereinafter referred to as "mixed fuel Fm" as appropriate) and are sent through the main fuel supply line 22. The main fuel supply line 22 is provided with a shutoff valve 24 for shutting off the mixed fuel Fm and a second flow rate adjustment valve 26 for adjusting the flow rate of the mixed fuel Fm.

[0021] The downstream side of the main fuel supply line 22 branches into a plurality of fuel branch supply lines 28a, 28b, ... for supplying the mixed fuel Fm to a plurality of fuel injection nozzles 29 (see FIG. 2) provided in the combustor 2. The plurality of fuel injection nozzles 29 include a plurality of main fuel injection nozzles, and at least some of these main fuel injection nozzles 28 are grouped as nozzle groups, and the fuel distribution ratio for each group is configured to be variable. Each of the plurality of fuel branch supply lines 28a, 28b, ... is provided with a third flow rate control valve 30a, 30b, ... and a shutoff valve 31a, 31b, ... for adjusting the flow rate of the mixed fuel Fm flowing through each line.

[0022] The multiple fuel injection nozzles 29 may include a pilot fuel injection nozzle, a top hat fuel injection nozzle, etc.

[0023] The compressor 3 also includes an inlet guide vane (IGV) 32. The opening degree of the inlet guide vane 32 is variably controlled by a gas turbine control device 100 described later, so that the flow rate of the combustion air A supplied to the combustor 2 can be adjusted. As shown in FIG. 2, the combustor 2 also has a bypass passage 34 for bypassing and supplying a part of the air in the casing. The bypass passage 34 is connected to a downstream space 38b (see FIG. 2) of the combustor 2, so that the air in the casing can be supplied as bypass air Abypass. A bypass valve 35 is provided in the bypass passage 34, and the flow rate of the bypass air Abypass can be controlled by adjusting the opening degree of the bypass valve 35.

[0024] 2, in the combustion chamber 38 of the combustor 2, the mixed fuel Fm injected from the fuel injection nozzle 29 is mixed with the combustion air A supplied from the compressor 3 and combusted. In an upstream space 38a, which is a relatively front half of the combustion chamber 38, a flame is formed by mixing and burning the mixed fuel Fm and the combustion air A, and downstream of this is provided a downstream space 38b through which the generated combustion gas flows out toward the turbine 6. The downstream space 38b is surrounded by a cylindrical body 39, and the bypass passage 34 is connected to the cylindrical body 39 so as to communicate with the downstream space 36.

[0025] Further, a temperature sensor 40 is installed downstream of the blades (moving blades or stationary blades) of the turbine 6 to detect a blade path temperature BPT, which is the temperature of the combustion gas at that position. The temperature sensor 40 is, for example, a thermocouple, but is not limited to this. As described above, in a gas turbine 1 equipped with a combustor 2 capable of co-firing the first fuel F1 and the second fuel F2, flashback (backfire) is more likely to occur than in the case of mono-firing the first fuel F1. Such flashback can be detected from a trend change in the blade path temperature BPT.

[0026] Next, a gas turbine control device 100 for controlling the gas turbine 1 having the above configuration will be described. The gas turbine control device 100 is a control unit for controlling the gas turbine 1, and is composed of, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and a computer-readable storage medium. A series of processes for realizing various functions is stored in a storage medium or the like in the form of a program, for example, and the CPU reads the program into the RAM or the like and executes information processing and arithmetic processing to realize various functions. The program may be installed in a ROM or other storage medium in advance, may be provided in a state stored in a computer-readable storage medium, or may be distributed via a wired or wireless communication means. The computer-readable storage medium is, for example, a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, or a semiconductor memory.

[0027] 3 is a block diagram showing a functional configuration of a gas turbine control device 100 according to an embodiment. The gas turbine control device 100 includes a load acquisition unit 102, a mixed-fuel ratio control unit 104, a bypass valve opening control unit 106, a temperature detection unit 108, and a flashback determination unit 110.

[0028] The load acquisition unit 102 is configured to acquire the load L of the gas turbine 1. The load L may be a load command for the gas turbine 1, or may be a load that is actually output by the gas turbine 1. In the latter case, the output of a generator or the like connected to the turbine 6 may be acquired as the actual output of the gas turbine 1.

[0029] The mixed-fuel ratio control unit 104 is configured to control the mixed-fuel ratio R of the second fuel F2 based on the load L of the gas turbine 1 acquired by the load acquisition unit 102. In this embodiment, the mixed-fuel ratio R is calculated using the flow rate of the first fuel F1 measured by the flow meter 7 provided in the first fuel supply line 8 and the flow rate of the second fuel F2 measured by the flow meter 15 provided in the second fuel supply line 16. The mixed-fuel ratio control unit 104 controls the mixed-fuel ratio R to increase as the load L increases.

[0030] The bypass valve opening control unit 106 is configured to control the opening D of the bypass valve 35 provided in the bypass passage 34. The opening control of the bypass valve 35 by the bypass valve opening control unit 106 is performed based on the load L of the gas turbine 1.

[0031] Here, a reference technique will be described regarding a control example of the bypass valve opening control unit 106. Fig. 4 is a graph showing the relationship between the opening D and mixed combustion ratio R of the bypass valve 35 controlled by the bypass valve opening control unit 106 in the reference technique, and the load L of the gas turbine 1 (hereinafter, the control example according to the reference technique shown with reference to Fig. 4 will be appropriately referred to as the "first control mode").

[0032] The opening control of the bypass valve 35 in the first control mode is performed so that the opening D of the bypass valve 35 decreases as the load L of the gas turbine 1 increases. That is, the opening D of the bypass valve 35 is controlled to decrease with an increase in the load L of the gas turbine. As a result, as the load L of the gas turbine is increased, the opening of the bypass valve 35 decreases at a first rate C1, and the bypass valve 35 is controlled to be in a fully closed state at a predetermined first reference load Lref1.

[0033] In the example of FIG. 4, the behavior of the aperture of the bypass valve 35 decreasing linearly with an increase in the load L is shown. In this control example, when the load L of the gas turbine 1 is relatively small, the flow rate of the mixed fuel Fm supplied to the combustor 2 is relatively small, so the aperture D of the bypass valve is increased. By increasing the flow rate of the bypass air Abypass in this way, the fuel-air ratio in the combustion chamber 38 can be made appropriate and the combustion efficiency can be improved. On the other hand, when the load L of the gas turbine 1 is large, the flow rate of the mixed fuel Fm supplied to the combustor 2 is also relatively large, so the aperture D of the bypass valve is reduced to reduce the flow rate of the bypass air Abias. As a result, the fuel-air ratio in the combustion chamber 38 can be made appropriate and the combustion efficiency can be improved.

[0034] In the first control mode, the mixed-combustion ratio control unit 104 controls the mixed-combustion ratio R of the second fuel F2, which is hydrogen gas, to increase as the load L increases. More specifically, when the load L is sufficiently small, the mixed-combustion ratio R of the second fuel F2 is controlled to zero percent, so that the single-fuel operation is performed using the first fuel F1. However, when the load L becomes large to a certain extent, the supply of the second fuel F2 is started, and the system transitions to the mixed-combustion operation. In FIG. 4, the system transitions from the single-fuel operation to the mixed-combustion operation at the second reference load Lref2, which is smaller than the first reference load Lref1, as the boundary. In the mixed-combustion operation region, the supply amount of the second fuel F2 increases as the load L increases, and the mixed-combustion ratio R also gradually increases, eventually reaching a preset upper limit value (30% in this embodiment).

[0035] Returning to Fig. 3, the temperature detection unit 108 is configured to detect the blade path temperature BPT by acquiring the detection value of the temperature sensor 40. The blade path temperature BPT detected by the temperature detection unit 108 is input to a flashback determination unit 110 and used to detect and determine the occurrence of a flashback.

[0036] The flashback determination unit 110 determines whether or not a flashback has occurred based on a trend change in the blade path temperature BPT. The method of determining whether or not a flashback has occurred by the flashback determination unit 110 follows a known example, and detailed description thereof will be omitted here.

[0037] 5 is a perspective view showing the combustor 2 shown in FIG. 2, and FIG. 6 is a cross-sectional view showing the hot spot HS in cross section B of FIG. 5. In the control example (first control mode) in the above-mentioned reference technology, as shown in FIG. 4, in a relatively low load range (a range equal to or less than the first reference load Lref1) in the mixed combustion region, the bypass valve 35 is in an open state (a state in which the opening degree D is greater than 0%). At this time, as shown in FIG. 5, the bypass air Abypass flows into the downstream space 38b of the combustor 2 through the bypass passage 34, and the inflow state of the mainstream (combustion air A) in the downstream space 38b changes. As a result, as shown in FIG. 6, the hot spot HS in the downstream space 38b changes, and the blade path temperature BPT detected by the temperature sensor 40 also changes.

[0038] If the flashback determination unit 110 determines whether a flashback has occurred based on the blade path temperature BPT that varies in this way, there is a risk that the flashback determination unit 110 may erroneously determine that a flashback has occurred even when a flashback has not actually occurred. This problem can be preferably solved by a control example according to this embodiment (hereinafter also referred to as the "second control mode" as appropriate) that will be described next.

[0039] 7A and 7B are graphs showing the relationship between the opening D of the bypass valve 35 and the mixed-combustion ratio R, and the load L of the gas turbine 1, in a control example (second control mode) according to this embodiment. In the control example according to this embodiment, like the reference technology (first control mode) described above, the bypass valve control unit 106 controls the opening of the bypass valve 35 to decrease as the mixed-combustion ratio R of the second fuel F2 increases on the relatively low mixed-combustion ratio side, but in a range where the mixed-combustion ratio R is greater than the first threshold value R1, the opening of the bypass valve 35 is controlled so that the bypass valve 35 is fully closed.

[0040] Here, the first threshold value R1 is smaller than the maximum mixed combustion ratio corresponding to the rated operation of the gas turbine. In FIG. 7A, the first threshold value R1 is set to an arbitrary intermediate value between the maximum mixed combustion ratio of 30% and zero%, but as shown in FIG. 7B, the first threshold value R1 may be set to zero%. As a result, in the mixed combustion region where flashback is likely to occur, the bypass supply of the combustion air A via the bypass valve 35 is suppressed, and the inflow state of the mainstream in the downstream space 38b of the combustor 2 is stabilized. As a result, the blade path temperature BPT does not fluctuate due to the bypass supply of the combustion air A. Therefore, the flashback determination unit 110 can appropriately detect flashback based on the trend change of the blade path temperature BPT.

[0041] When the mixed combustion ratio R is greater than the first threshold value R1, the distribution ratio of the mixed fuel Fm to the multiple fuel injection nozzles 29 of the combustor 2 may be adjusted (the adjustment of the distribution ratio of the mixed fuel Fm to the multiple fuel injection nozzles 29 of the combustor 2 may be performed in a range in which the mixed combustion ratio R is greater than the first threshold value R1 (i.e., in a range in which the bypass valve 35 is controlled to be fully closed)). Here, FIG. 8 is a diagram showing an arrangement layout of the main fuel injection nozzles 42 among the multiple fuel injection nozzles 29 of the combustor 2 of FIG. 1 from the downstream side. The multiple main fuel injection nozzles 42 are arranged around the pilot fuel injection nozzle 44 in the center along the circumferential direction. The multiple main fuel injection nozzles 42 are classified into multiple main fuel injection nozzle groups. In this embodiment, a total of eight main fuel injection nozzles 42 are provided, and are classified into a first main fuel injection nozzle group 42A consisting of three main fuel injection nozzles 42 shown in the lower part of FIG. 8 and a second main fuel injection nozzle group 42B consisting of the remaining five main fuel injection nozzles 42.

[0042] In this case, the distribution rate of the mixed fuel Fm to each fuel injection nozzle 29 can be a fuel distribution ratio KMB defined by the following equation as a value obtained by dividing the second main flow rate MBCSO, which is the flow rate of the fuel supplied to the second main fuel injection nozzle group 42B, by the sum of the first main flow rate MACSO, which is the flow rate of the fuel supplied to the first main fuel injection nozzle group 42A, and the second main flow rate MBCSO. KMB = MBCSO / (MACSO + MBCSO)

[0043] In one control example, as the load L of the gas turbine 1 decreases, the fuel distribution ratio KMB increases (i.e., the second main flow rate MBCSO is increased relative to the sum of the first main flow rate MACSO and the second main flow rate MBCSO). As a result, even in a region where the mixed combustion ratio R is relatively large, good combustion efficiency can be obtained by ensuring the flame temperature and fuel velocity while keeping the bypass valve 35 fully closed.

[0044] On the other hand, in the range where the mixed combustion ratio R is equal to or less than the first threshold value, the opening degree D of the bypass valve 35 is controlled based on the load L of the gas turbine 1. That is, in this range, similar to the above-mentioned reference technology, the opening degree D of the bypass valve 35 is controlled to decrease as the load L increases. As a result, in the mono-fuel combustion region where the risk of false detection of flashback is lower than in the mixed combustion region, the opening degree of the bypass valve 35 is controlled to increase as the load L of the gas turbine 1 decreases, thereby suppressing deterioration of the fuel-air ratio in the low load region and achieving good combustion efficiency.

[0045] Furthermore, in the range where the mixed combustion ratio R with the bypass valve 35 in the open state is equal to or less than the first threshold value R1, when the load L of the gas turbine 1 is a second load L2 that is smaller than the first load L1 corresponding to the first threshold value R1, the opening degree D of the bypass valve is controlled so that the load L of the gas turbine 1 decreases at a constant rate (first rate C1) with respect to an increase in the load L, as in the reference technology shown in FIG. When the load L of the gas turbine 1 is equal to or greater than the second load L2 and is the first load L1, the opening degree D of the bypass valve 35 is controlled to decrease at a second rate C2 greater than the first rate C1 with respect to an increase in the load L1 of the gas turbine 1. In other words, control similar to the prior art is performed when the load L is in the range of 0 ≦ L ≦ L2, but in the range of L2 < L ≦ L1, the opening degree D is controlled to continuously change so that the bypass valve 35 is fully closed when the load L of the gas turbine 1 reaches the first load L1.

[0046] As described above, according to each of the above embodiments, when controlling so that the co-firing rate R increases as the load L of the gas turbine 1 increases, when the co-firing rate R of the second fuel F2 is greater than the first threshold value R1, the bypass valve 35 is controlled to be fully closed. As a result, during co-firing operation in which flashback is likely to occur, the bypass supply of the combustion air A via the bypass valve 35 is suppressed, so that the inflow state of the main stream in the downstream space 38b of the combustor 2 is stabilized. As a result, the blade passage temperature BPT does not fluctuate due to the bypass-supplied combustion air, and flashback can be appropriately detected based on the trend change of the blade passage temperature BPT.

[0047] In addition, within the scope not departing from the gist of the present disclosure, it is possible to appropriately replace the components in the above-described embodiments with well-known components, and the above-described embodiments may be appropriately combined.

[0048] The content described in each of the above embodiments is understood as follows, for example.

[0049] (1) A gas turbine control device according to one aspect includes a combustor that mixes a first fuel and a mixed fuel including a second fuel having a lower heat amount per unit volume than the first fuel with combustion air and is capable of combustion, a bypass passage capable of bypassing at least a part of the combustion air and supplying it to the downstream space of the combustor, a bypass valve provided in the bypass passage, A gas turbine control device for controlling a gas turbine comprising: a mixed-combustion ratio control unit that controls the mixed-combustion ratio of the second fuel to be increased as the load of the gas turbine increases; a bypass valve control unit for controlling an opening degree of the bypass valve based on the mixed combustion ratio; Equipped with The bypass valve control unit controls the bypass valve to a fully closed state when the mixed combustion ratio is greater than a first threshold value.

[0050] According to the above aspect (1), when the mixed-fuel ratio is controlled to increase as the load on the gas turbine increases, the opening of the bypass valve is decreased with respect to the increase in the mixed-fuel ratio, and the bypass valve is controlled to be in a fully closed state at a mixed-fuel ratio greater than a first threshold value. As a result, during mixed-fuel operation in which flashback is likely to occur, the bypass supply of combustion air through the bypass valve is suppressed, and the inflow state of the mainstream in the downstream space of the combustor is stabilized. As a result, the blade path temperature is not fluctuated by the bypass supply of combustion air, and flashback can be appropriately detected based on the trend change of the blade path temperature.

[0051] (2) In another embodiment, in the above embodiment (1), The first threshold value is smaller than a maximum mixed-fuel ratio corresponding to rated operation of the gas turbine.

[0052] According to the above aspect (2), the first threshold value, which is the minimum mixed-fuel ratio at which the bypass valve is controlled to the fully closed state, is set to be smaller than the maximum mixed-fuel ratio corresponding to the rated operation of the gas turbine.

[0053] (3) In another embodiment, in the above embodiment (2), The first threshold is zero percent.

[0054] According to the above aspect (3), the first threshold value, which is the minimum mixed-fuel ratio at which the bypass valve is controlled to the fully closed state, is set to zero percent.

[0055] (4) In another embodiment, in any one of the above (1) to (3), When the opening degree is reduced as the load of the gas turbine increases, the bypass valve control unit controls the bypass valve to a fully closed state in a load range greater than a first load corresponding to the first threshold value.

[0056] According to the above aspect (4), the bypass valve is controlled to the fully closed state in the load range in which the mixed-fuel ratio is greater than the first threshold value, so that the bypass supply of combustion air via the bypass valve can be suppressed during mixed-fuel operation in which flashback is likely to occur.

[0057] (5) In another embodiment, in the above embodiment (4), The bypass valve control unit is controlling an opening degree of the bypass valve to decrease at a first rate in response to an increase in the load of the gas turbine when the load of the gas turbine is equal to or lower than a second load that is smaller than the first load; When the load of the gas turbine is equal to or greater than the second load and equal to or less than the first load, the opening of the bypass valve is controlled to decrease at a second rate greater than the first rate in response to an increase in the load of the gas turbine.

[0058] According to the above aspect (5), in a range where the load of the gas turbine is equal to or less than the second load, the opening degree of the bypass valve is controlled so that the load of the gas turbine decreases at a first rate in response to an increase in the load of the gas turbine. On the other hand, in a range where the load of the gas turbine is between the second load and the first load, the opening degree of the bypass valve is controlled so that the load of the gas turbine decreases at a second rate that is larger than the first rate in response to an increase in the load of the gas turbine.

[0059] (6) In another embodiment, in any one of the above (1) to (5), When the mixed combustion ratio is greater than at least the first threshold value, a distribution ratio of the mixed fuel to a plurality of fuel injection nozzles included in the combustor is changed.

[0060] According to the above aspect (6), when the mixed fuel ratio of the gas turbine is greater than the first threshold, the bypass valve is controlled to a fully closed state. In this case, the distribution ratio of the mixed fuel to the multiple fuel injection nozzles of the combustor is changed, thereby suppressing a decrease in combustion efficiency. For example, when the load of the gas turbine is relatively low, the fuel injection amount for each fuel injection nozzle can be increased by supplying the mixed fuel to some of the fuel injection nozzles in a limited manner, compared to the case where the mixed fuel is supplied to all of the fuel injection nozzles, thereby improving the combustion efficiency.

[0061] (7) In another embodiment, in any one of the above (1) to (6), a temperature sensor for detecting a temperature of the combustion gas generated by the combustor at a position downstream of a turbine rear stage blade; a flashback determination unit for determining occurrence of a flashback in the combustor based on the temperature; Equipped with.

[0062] According to the above aspect (7), the bypass valve is controlled to be fully closed when the mixed combustion ratio of the gas turbine is greater than the first threshold value, thereby suppressing the influence of hot spot fluctuations and enabling accurate determination of the occurrence of flashback based on the blade path temperature.

[0063] (8) A gas turbine control method according to one aspect includes the steps of: a combustor capable of mixing a mixed fuel containing a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel with combustion air and combusting the mixed fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; 1. A gas turbine control method for controlling a gas turbine comprising: controlling a mixed combustion ratio of the second fuel to be increased as a load of the gas turbine increases; controlling an opening degree of the bypass valve based on the mixed combustion ratio; Equipped with In the step of controlling the bypass valve, when the mixed combustion ratio is greater than a first threshold value, the bypass valve is controlled to a fully closed state.

[0064] According to the above aspect (8), when the mixed-fuel ratio is controlled to increase as the load on the gas turbine increases, the opening of the bypass valve is decreased with respect to the increase in the mixed-fuel ratio, and the bypass valve is controlled to be in a fully closed state at a mixed-fuel ratio greater than the first threshold. As a result, during mixed-fuel operation in which flashback is likely to occur, the bypass supply of combustion air through the bypass valve is suppressed, and the inflow state of the mainstream in the downstream space of the combustor is stabilized. As a result, the blade path temperature is not fluctuated by the bypass supply of combustion air, and flashback can be appropriately detected based on the trend change of the blade path temperature.

[0065] (9) A method for modifying a gas turbine according to one aspect includes the steps of: a combustor capable of mixing a first fuel with combustion air and combusting the first fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; Equipped with A gas turbine modification method for modifying a gas turbine capable of implementing a dedicated combustion operation mode in which an opening degree of the bypass valve is controlled based on a load of the gas turbine, the method comprising the steps of: A mixed fuel containing the first fuel and a second fuel having a lower heat value per unit volume than the first fuel is mixed with the combustion air in the combustor and combusted, and when a mixed combustion ratio of the second fuel is greater than a first threshold value, a mixed combustion operation mode in which the bypass valve is controlled to a fully closed state is modified to be switchable to the mono-fuel operation mode.

[0066] According to the above aspect (9), a gas turbine equipped with a combustor capable of mixing a first fuel such as natural gas with combustion air and burning it (mono-combustion) is modified to enable a mixed-combustion operation. In the mixed-combustion operation, in addition to the first fuel, a second fuel such as hydrogen, which has a lower calorific value per unit volume than the first fuel, is mixed and burned, and the bypass valve is controlled to be fully closed when the mixed-combustion ratio of the second fuel is greater than the first threshold value. As a result, during the mixed-combustion operation in which flashback is likely to occur, the bypass supply of the combustion air through the bypass valve is suppressed, and the inflow state of the mainstream in the downstream space of the combustor is improved so as to be stable. As a result, the blade path temperature does not fluctuate due to the bypass-supplied combustion air, and flashback can be appropriately detected based on the trend change of the blade path temperature. In the gas turbine modified in this way, for example, when the supply of the second fuel is not possible, a mono-combustion operation mode is implemented, while when the supply of the second fuel is possible, a mixed-combustion operation mode is implemented, thereby making it possible to selectively switch the operation mode. [Explanation of symbols]

[0067] 1. Gas turbine 2. Combustor 3. Compressor 6. Turbine 7 First fuel source 8. First fuel supply line 10 Flow meter 13. Shutoff valve 14 Secondary fuel source 15 Flow meter 16 Second fuel supply line 18 First flow control valve 22 Main fuel supply line 24 Shut-off valve 25 Confluence 26 Second flow control valve 29 Fuel injection nozzle 30a, 30b, ... third flow rate adjustment valve 31a, 31b, ...Shut-off valve 32 Inlet guide vane 34 Bypass Passage 35 Bypass valve 38 Combustion chamber 38a Upstream space 38b Downstream space 39 Cylinder 40 Temperature Sensor 42 Main fuel injection nozzle 44 Pilot fuel injection nozzle 100 Gas turbine control device 102 Load acquisition section 104 Mixed-fuel ratio control unit 106 Bypass valve opening control unit 108 Temperature detection unit 110 Flashback Judgment Section

Claims

1. a combustor capable of mixing a mixed fuel containing a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel with combustion air and combusting the mixed fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; A gas turbine control device for controlling a gas turbine comprising: a mixed-combustion ratio control unit that controls the mixed-combustion ratio of the second fuel to be increased as the load of the gas turbine increases; a bypass valve control unit for controlling an opening degree of the bypass valve based on the mixed combustion ratio; Equipped with The gas turbine control device, when the mixed combustion ratio is greater than a first threshold value, the bypass valve control unit controls the bypass valve to a fully closed state.

2. The gas turbine control device according to claim 1 , wherein the first threshold value is smaller than a maximum mixed-fuel ratio corresponding to a rated operation of the gas turbine.

3. The gas turbine control system of claim 2 , wherein the first threshold is zero percent.

4. 3. The gas turbine control device according to claim 1, wherein, when the opening degree is reduced as the load of the gas turbine increases, the bypass valve control unit controls the bypass valve to a fully closed state in a load range greater than a first load corresponding to the first threshold value.

5. The bypass valve control unit is controlling an opening degree of the bypass valve to decrease at a first rate in response to an increase in the load of the gas turbine when the load of the gas turbine is equal to or lower than a second load that is smaller than the first load; 5. The gas turbine control device according to claim 4, wherein, when a load of the gas turbine is equal to or greater than the second load and is equal to or less than the first load, the opening of the bypass valve is controlled to decrease at a second rate greater than the first rate in response to an increase in the load of the gas turbine.

6. 3 . The gas turbine control device according to claim 1 , further comprising: a distribution ratio of the mixed fuel to a plurality of fuel injection nozzles included in the combustor, the distribution ratio being greater than at least the first threshold value. 4 .

7. a temperature sensor for detecting a temperature of the combustion gas generated by the combustor at a position downstream of a turbine rear stage blade; a flashback determination unit for determining occurrence of a flashback in the combustor based on the temperature; The gas turbine control device according to claim 1 or 2, comprising:

8. a combustor capable of mixing a mixed fuel containing a first fuel and a second fuel having a lower calorific value per unit volume than the first fuel with combustion air and combusting the mixed fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; 1. A gas turbine control method for controlling a gas turbine comprising: controlling a mixed combustion ratio of the second fuel to be increased as a load of the gas turbine increases; controlling an opening degree of the bypass valve based on the mixed combustion ratio; Equipped with In the step of controlling the bypass valve, the bypass valve is controlled to a fully closed state when the mixed-fuel ratio is greater than a first threshold value.

9. a combustor capable of mixing a first fuel with combustion air and combusting the first fuel; a bypass passage capable of bypassing and supplying at least a portion of the combustion air to a downstream space of the combustor; A bypass valve provided in the bypass passage; Equipped with A gas turbine modification method for modifying a gas turbine capable of implementing a dedicated fuel operation mode in which an opening degree of the bypass valve is controlled based on a load of the gas turbine, the method comprising the steps of: a mixed fuel including the first fuel and a second fuel having a lower heat amount per unit volume than the first fuel is mixed with the combustion air in the combustor and combusted, and when a mixed-combustion ratio of the second fuel is greater than a first threshold value, the bypass valve is controlled to a fully closed state, and the mixed-combustion operation mode is modified to be switchable to the mono-fuel operation mode.

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