GAS TURBINE CONTROL DEVICE, GAS TURBINE CONTROL METHOD AND GAS TURBINE MODIFICATION METHOD

Abstract

This gas turbine control device controls a gas turbine equipped with: a combustion chamber capable of mixing and burning a first fuel and a second fuel with combustion air; a bypass channel capable of diverting and supplying at least a portion of the combustion air to a downstream chamber of the combustion chamber; and a bypass valve provided in the bypass channel. The gas turbine control device performs control such that the mixed combustion rate of the second fuel increases when the gas turbine load increases, and it controls the opening of the bypass valve based on the mixed combustion rate.The opening control of the bypass valve is carried out in such a way that the opening of the bypass valve is controlled so that the bypass valve is completely closed when the opening is reduced inversely proportional to the load of the gas turbine at a second load that is smaller than a first load at which the bypass valve is completely closed.

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.

[0002] The present application claims priority on the basis of Japanese patent application No. 2023-127430, which was filed with the Japanese Patent Office on August 4, 2023, and the contents of which are incorporated herein by reference. State of the art

[0003] For example, in a thermal power plant, a gas turbine, driven by a combustion gas produced by burning a fuel, is used as a turbine to drive a generator. This type of gas turbine contains a combustion chamber for burning the fuel, and the amount of fuel supplied to the combustion chamber is controlled to vary according to the gas turbine load. For example, in an operating condition where the gas turbine load is low, the amount of fuel supplied to the combustion chamber is reduced, thus decreasing the fuel-to-air ratio in a combustion range, and combustion efficiency is likely to deteriorate.

[0004] In PTL 1, to solve such a problem, during low-load operation of the gas turbine, some of the combustion air supplied to the combustion chamber is diverted through a bypass valve to a downstream space of the combustion chamber, so that a fuel-air ratio is kept high to ensure flame retention and combustion efficiency is improved. List of citations from patent literature

[0005] [PTL 1] Japanese unexamined patent application publication no. 2001-124338 Summary of the invention: Technical problem

[0006] In recent years, the active use of a fuel different from fossil fuels, such as hydrogen, or improvements in power generation efficiency have been considered as a means of reducing carbon dioxide (CO2) emissions, a cause of global warming, in thermal power plants. To reduce carbon dioxide emissions, it is desirable to increase the blending rate of a second fuel (hydrogen), which has a relatively lower calorific value per unit volume than a primary fuel, such as natural gas. However, because hydrogen has low ignition energy and a high combustion rate, increasing the blending rate of hydrogen increases the possibility of flame flashback (backflow of a flame) or similar issues.

[0007] The flame flashback generated in the gas turbine can be detected by a change in the blade channel temperature (BPT), which is the temperature of the combustion gas flowing through the turbine. The blade channel temperature is measured, for example, by a temperature sensor, such as a thermocouple, installed on the downstream side of the combustion chamber.

[0008] Here, as in PTL 1, when the gas turbine load is relatively low, a change occurs when some of the combustion air is diverted through the bypass valve to the downstream combustion chamber. This alters the inflow conditions in the downstream combustion chamber, causing fluctuations in the heat distribution (specifically, the location of a hotspot where the temperature rises). This affects the blade channel temperature measurement taken by the temperature sensor described above and can lead to erroneous detection of flame flashback based solely on the blade channel temperature reading.

[0009] At least one embodiment of the present disclosure was made in view of the above circumstances, and one object of it 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 flame flashback. Solution to the problem

[0010] To solve the above problem, according to at least one embodiment of the present disclosure, a gas turbine control device is provided for controlling a gas turbine, which includes a combustion chamber capable of mixing a mixed fuel, comprising a first fuel and a second fuel having a lower calorific value per unit volume and a faster combustion rate than the first fuel, with combustion air and burning the mixed fuel; a bypass channel capable of diverting at least a portion of the combustion air and supplying it to a downstream space of the combustion chamber; and a bypass valve provided in the bypass channel, wherein the gas turbine control device includes a mixed combustion rate control unit that performs control such that a mixed combustion rate of the second fuel is increased when the load of the gas turbine increases.and a bypass valve control unit which controls the opening degree of the bypass valve based on the mixed combustion rate, wherein the bypass valve control unit controls the bypass valve to be fully closed in a case where the mixed combustion rate is greater than a first threshold.

[0011] To solve the above problem, according to at least one embodiment of the present disclosure, a gas turbine control method is provided for controlling a gas turbine, which has a combustion chamber capable of mixing with combustion air and burning a mixed fuel comprising a first fuel and a second fuel having a lower calorific value per unit volume and a faster combustion rate than the first fuel, a bypass channel capable of diverting at least a portion of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve provided in the bypass channel, wherein the gas turbine control method includes a step of performing control such that a mixed combustion rate of the second fuel is increased when a load of the gas turbine increases.and includes a step of controlling the opening degree of the bypass valve based on the mixed combustion rate, wherein in the step of controlling the bypass valve, the bypass valve is controlled to be completely closed in a case where the mixed combustion rate is greater than a first threshold.

[0012] To solve the above problem, according to at least one embodiment of the present disclosure, a gas turbine modification method is provided for modifying a gas turbine capable of performing a dedicated combustion operating mode in which the opening degree of a bypass valve is controlled based on a load of the gas turbine, wherein the gas turbine comprises a combustion chamber capable of mixing a first fuel with combustion air and burning the first fuel, a bypass channel capable of diverting at least a portion of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve provided in the bypass channel, wherein the gas turbine modification method modifies a mixed-combustion operating mode in which the bypass valve is controlled to be fully closed.so that it can be switched to the dedicated combustion operating mode in a case where a mixed fuel containing the first fuel and a second fuel having a lower calorific value per unit volume and a faster combustion rate than the first fuel is mixed with the combustion air in the combustion chamber and burned, and where the mixed combustion rate of the second fuel is greater than a first threshold. Advantageous effects of the invention

[0013] 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 modification method that are capable of preventing faulty detection of flame flashback. Brief description of the drawings Fig. Figure 1 is a diagram that represents a schematic configuration of a gas turbine according to one embodiment. Fig. Figure 2 is a cross-sectional view that schematically depicts an internal configuration of a combustion chamber. Fig. 1 shows. Fig. Figure 3 is a block diagram representing a functional configuration of a gas turbine control device according to one embodiment. Fig. Figure 4 is a graph showing a relationship between the opening degree of a bypass valve and a mixed combustion rate in the prior art, which is controlled by a bypass valve opening control unit. Fig. 3 is controlled, and shows a load of a gas turbine. Fig. 5 is a perspective view that schematically depicts the Fig. The combustion chamber shown is 2. Fig. Figure 6 is a cross-sectional view showing a hotspot in a cross-section along line BB. Fig. 5 shows. Fig. Figure 7A is a graph showing a relationship between the opening degree of a bypass valve and a mixed combustion rate in an embodiment controlled by a bypass valve opening control unit. Fig. 3 is controlled, and shows a load of a gas turbine. Fig. Figure 7B is a graph showing a relationship between the opening degree of a bypass valve and a mixed combustion rate in a further embodiment controlled by a bypass valve opening control unit. Fig. 3 is controlled, and shows a load of a gas turbine. Fig. Figure 8 is a diagram showing the arrangement layout of a main fuel injector among several fuel injectors located in the combustion chamber of Fig. 1 are provided, pointing from a downstream side. Description of embodiments

[0014] Some embodiments of the present invention are described below with reference to the accompanying drawings. However, the configurations described in the embodiments or shown in the drawings are not intended to limit the scope of protection of the invention and are merely examples for illustrative purposes.

[0015] First, a gas turbine 1, which is a control target of a gas turbine control device 100 according to at least one embodiment of the present disclosure, is described with reference to Fig. 1 described. Fig. Figure 1 is a diagram showing a schematic configuration of the gas turbine 1 according to one embodiment, and Fig. Figure 2 is a cross-sectional view that schematically shows an internal configuration of a combustion chamber 2 of Fig. 1 shows.

[0016] The gas turbine 1 comprises a compressor 3, which generates compressed air (hereinafter optionally referred to as "combustion air A"), a combustion chamber 2, which produces combustion gas by mixing the combustion air generated by the compressor 3 with fuel, a fuel supply system 4, which supplies the fuel to the combustion chamber 2, and a turbine 6, which can be driven by the combustion gas. The compressor 3 and the turbine 6 are connected to each other on a shaft. In the gas turbine 1 with such a configuration, the combustion air A from the compressor 3 and the fuel (mixed fuel Fm, described below) supplied by the fuel supply system 4 are fed into the combustion chamber 2, where they are mixed and combusted to generate the combustion gas. The combustion gas flows into the turbine 6 and acts as a working fluid to drive the turbine 6.

[0017] The fuel supply system 4 treats a mixed fuel, in which a first fuel F1 and a second fuel F2 are mixed, as a single fuel to be supplied to the combustion chamber 2. The second fuel F2 is a fuel that has a lower calorific value per unit volume and a faster combustion rate than the first fuel F1. In the present 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, which is connected to the first fuel supply source 7. A flow meter 10 for detecting a 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, which is connected to the second fuel supply source 14. The second fuel supply line 16 is equipped with a first flow control valve 18 for regulating the flow rate of the second fuel F2, a first shut-off 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 are connected to a main fuel supply line 22 by being joined together at a connection point 25 located on a downstream side. The first fuel F1 and the second fuel F2, which are combined and mixed at the connection point 25 (hereinafter optionally referred to as "mixed fuel Fm"), are supplied by the main fuel supply line 22. The main fuel supply line 22 is provided with a shut-off valve 24, which shuts off the mixed fuel Fm, and a second flow control valve 26, which regulates the flow rate of the mixed fuel Fm.

[0021] The downstream side of the main fuel supply line 22 is branched into several fuel branch supply lines 28a, 28b, ... to supply the mixed fuel Fm to several fuel injection nozzles 29 (see Fig. 2), which are provided in the combustion chamber 2. The multiple fuel injectors 29 contain multiple main fuel injectors, and at least some of the main fuel injectors 28 are grouped as a nozzle group, and a fuel distribution ratio for each group is configured to be variable. Third flow control valves 30a, 30b, ... and shut-off valves 31a, 31b, ... for controlling a flow rate of the mixed fuel Fm flowing through each line are provided in each of the multiple fuel branch supply lines 28a, 28b, ...

[0022] It should be noted that the multiple fuel injectors 29 may include a pilot fuel injector, a cylinder fuel injector, or the like.

[0023] Furthermore, the compressor contains 3 inlet guide vanes (IGVs) 32. The opening degree of the inlet guide vane 32 is variably controlled by the gas turbine control device 100 described later, and the flow rate A of the combustion air supplied to the combustion chamber 2 can be regulated. In addition, as described in Fig. Figure 2 shows that combustion chamber 2 has a bypass channel 34 for diverting and supplying a portion of the casing air. The bypass channel 34 communicates with a downstream chamber 38b (see Figure 2). Fig. 2) of the combustion chamber 2, so that the housing air can be supplied as bypass air. A bypass valve 35 is provided in the bypass channel 34, and the flow rate of the bypass air can be controlled by regulating the opening degree of the bypass valve 35.

[0024] As in Fig. As shown in Figure 2, in a combustion chamber 38 of combustion chamber 2, the mixed fuel Fm injected by the fuel injector 29 is mixed with the combustion air A supplied by the compressor 3 and combusted. In an upstream space 38a, which is a relatively forward half-section of combustion chamber 38, the mixed fuel Fm and the combustion air A are mixed and combusted to form a flame, and the downstream space 38b, in which the generated combustion gas flows towards the turbine 6, is provided on a downstream side of this space. The downstream space 38b is surrounded by a cylindrical body 39, and the bypass channel 34 is connected to the cylindrical body 39 to communicate with the downstream space 36.

[0025] Furthermore, a temperature sensor 40 is installed on the downstream side of the blade (rotor blade or stator blade) of turbine 6 to detect a blade channel temperature BPT, which is the temperature of the combustion gas at that point. The temperature sensor 40 is, for example, a thermocouple, but is not limited to this. In the gas turbine 1, which contains the combustion chamber 2 capable of mixing and burning the first fuel F1 and the second fuel F2 as described above, flame flashback is more likely to occur compared to a case where the first fuel F1 is burned exclusively. The flame flashback can be detected by a change in the trend of the blade channel temperature BPT.

[0026] The following describes a gas turbine control device 100 for controlling the gas turbine 1 with the configuration described above. The gas turbine control device 100 is a control unit that controls the gas turbine 1 and is configured, for example, with a central processing unit (CPU), random-access memory (RAM), read-only memory (ROM), and a computer-readable storage medium or the like. A series of processing operations for achieving various functions is stored, for example, on a storage medium or the like in the form of a program, and the CPU reads the program into the RAM or the like and performs processing for information processing and computation to achieve the various functions.The program can be a form pre-installed in ROM or other storage medium, a form stored in a state on a computer-readable storage medium, or a form delivered via wired or wireless communication. Computer-readable storage mediums include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, and the like.

[0027] Fig. Figure 3 is a block diagram illustrating a functional configuration of the gas turbine control device 100 according to one embodiment. The gas turbine control device 100 includes a load sensing unit 102, a mixture combustion rate control unit 104, a bypass valve opening control unit 106, a temperature detection unit 108, and a flame flashback determination unit 110.

[0028] The load sensing unit 102 is configured to detect a load L of gas turbine 1. The load L can be a load command for gas turbine 1 or it can be a load actually output by gas turbine 1. In the latter case, the power output of a generator connected to turbine 6, or the like, can be detected as the actual power output of gas turbine 1.

[0029] The mixed combustion rate control unit 104 is configured to control a mixed combustion rate R of the second fuel F2 based on the load L of the gas turbine 1 detected by the load sensing unit 102. In the present embodiment, the mixed combustion rate R is calculated using a flow rate of the first fuel F1, measured by the flow meter 7 located in the first fuel supply line 8, and a flow rate of the second fuel F2, measured by the flow meter 15 located in the second fuel supply line 16. The mixed combustion rate control unit 104 controls the mixed combustion rate R so that it increases with increasing load L.

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

[0031] Here, the state of the art is described with regard to a control example of the bypass valve opening control unit 106. Fig. Figure 4 is a graph showing a relationship between the opening degree D of the bypass valve 35 and the mixed combustion rate R, which is controlled by the bypass valve opening control unit 106 in the prior art, and the load L of the gas turbine 1 (below is a control example according to the prior art, which refers to Fig. 4 is shown, possibly referred to as a “first control mode”).

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

[0033] In the example of Fig. Figure 4 shows a behavior in which the opening degree of the bypass valve 35 decreases linearly with an increase in the load L. 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 combustion chamber 2 is relatively small, and thus the opening degree D of the bypass valve is increased. By increasing the flow rate of the bypass air in this way, the fuel-air ratio in the combustion chamber 38 can be adjusted, 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 combustion chamber 2 is also relatively large, and thus the opening degree D of the bypass valve is reduced to decrease the flow rate of the bypass air.Therefore, the fuel-air ratio in the combustion chamber 38 can be adjusted to suit the combustion efficiency.

[0034] Furthermore, in the first control mode, the mixed combustion rate control unit 104 is configured so that the mixed combustion rate R of the hydrogen gas, which is the second fuel F2, increases as the load L increases. Specifically, the mixed combustion rate R of the second fuel F2 is controlled so that it is 0% when the load L is sufficiently low, thus enabling dedicated operation using the first fuel F1. However, if the load L increases to a certain extent, the second fuel F2 is introduced to switch to mixed combustion operation. Fig. 4. The transition from dedicated operation to mixed combustion operation with a second reference load Lref2, which is smaller than the first reference load Lref1, is defined as a boundary. In a mixed combustion operating range, the feed rate of the second fuel F2 increases as the load L increases, and the mixed combustion rate R gradually increases, eventually reaching a preset upper limit (30% in the present embodiment).

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

[0036] The Flame Flashback Determination Unit 110 determines whether a flame flashback has occurred based on the trend change in the blade channel temperature (BPT). A method for determining flame flashback using the Flame Flashback Determination Unit 110 follows a known example, and its details are omitted here.

[0037] Here is Fig. 5 a perspective view that schematically shows the in Fig. Combustion chamber 2 shown, and Fig. 6 is a cross-sectional view showing a hotspot HS in a cross-section along line BB of Fig. Figure 5 shows. In the control example (first control mode) in the state of the art described above, as shown in Fig. As shown in Figure 4, in a relatively low load range (a range of the first reference load Lref1 or less) in a mixed combustion range, the bypass valve 35 is in an open state (an opening degree D is greater than 0%). In this case, as shown in Figure 4, the bypass valve 35 is in an open state (an opening degree D is greater than 0%). Fig. As shown in Figure 5, the bypass air passes through the bypass channel 34 into the downstream chamber 38b of the combustion chamber 2, and thus the inflow state of the main flow (combustion air A) in the downstream chamber 38b changes. As a result, as shown in Fig. Figure 6 shows the hotspot HS in the downstream space 38b, and thus the blade channel temperature BPT detected by the temperature sensor 40 also fluctuates.

[0038] In the flame flashback determination unit 110, in a case where the occurrence of flame flashback is determined based on the blade channel temperature BPT, which fluctuates in this way, it is likely that the flame flashback will be incorrectly determined to have occurred, regardless of whether the flame flashback actually occurred or not. Such a problem can be suitably solved by a control example (hereinafter optionally also referred to as a "second control mode") according to the present embodiment described below.

[0039] Fig. 7A and Fig. Figure 7B shows a relationship between the opening degree D of the bypass valve 35 and the mixed combustion rate R in the control example (second control mode) according to the present embodiment and the load L of the gas turbine 1. In the control example according to the present embodiment, the bypass valve opening control unit 106 is similar to the prior art described above (first control mode) in that the opening degree of the bypass valve 35 is controlled such that it decreases with respect to an increase in the mixed combustion rate R of the second fuel F2 on a relatively low mixed combustion rate side, but the opening degree control of the bypass valve 35 is carried out such that the bypass valve 35 is completely closed in a range where the mixed combustion rate R is greater than a first threshold value R1.

[0040] Here, the first threshold value R1 is set so that it is smaller than the maximum mixed combustion rate corresponding to the nominal operation of the gas turbine. Fig. 7A is the first threshold value R1 set to any intermediate value between 30%, which is the maximum mixed combustion rate, and 0%, but, as in Fig. As shown in Figure 7B, the first threshold value R1 can be set to 0%. Therefore, in the mixed combustion zone where flame flashback is likely to occur, the bypass supply of combustion air A through the bypass valve 35 is suppressed, thus stabilizing the main flow condition in the downstream space 38b of combustion chamber 2. As a result, the blade channel temperature BPT does not fluctuate due to the redirected combustion air A. Therefore, the flame flashback detection unit 110 can appropriately detect flame flashback based on the trend change in the blade channel temperature BPT.

[0041] Furthermore, in a case where the mixed combustion rate R is greater than the first threshold value R1, the distribution ratio of the mixed fuel Fm to the multiple fuel injectors 29 provided in the combustion chamber 2 can be controlled (the distribution ratio of the mixed fuel Fm to the multiple fuel injectors 29 provided in the combustion chamber 2 can be controlled in a range where the mixed combustion rate R is greater than the first threshold value R1 (that is, a range where the bypass valve 35 is completely closed)). Here is Fig. 8 a diagram showing an arrangement layout of a main fuel injector 42 among the several fuel injectors 29 located in the combustion chamber 2 of Fig. 1 are provided, from a downstream side. The multiple main fuel injectors 42 are arranged around a pilot fuel injector 44 along a circumferential direction. Furthermore, the multiple main fuel injectors 42 are classified into multiple main fuel injector groups. In the present embodiment, a total of eight main fuel injectors 42 are provided, and the main fuel injectors 42 are divided into a first main fuel injector group 42A, which comprises three main fuel injectors 42 located below in Fig. 8 are shown, and a second main fuel injector group 42B, which contains five remaining main fuel injectors 42, is classified.

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

[0043] As one example of the control, the fuel distribution ratio KMB increases when the load L of gas turbine 1 decreases (that is, 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). Therefore, even in a range where the mixed combustion rate R is relatively large, good combustion efficiency can be obtained by ensuring a flame temperature or fuel velocity while keeping the bypass valve 35 in the fully closed state.

[0044] On the other hand, in a range where the mixed combustion rate R is equal to or less than the first threshold, 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, the opening degree D of the bypass valve 35 is controlled to decrease as the load L increases, similar to the prior art described above. Therefore, in the dedicated combustion range, where the risk of faulty flame flashback detection is lower than in the mixed combustion range, the opening degree of the bypass valve 35 is controlled to increase as the load L of the gas turbine 1 decreases, thus suppressing the deterioration of the fuel-air ratio in the low-load range and maintaining good combustion efficiency.

[0045] Furthermore, in a case where the load L of gas turbine 1 is a second load L2 that is smaller than a first load L1 corresponding to the first threshold R1 in a range where the mixed combustion rate R of the bypass valve 35 in the open state is equal to or less than the first threshold R1, the opening degree D of the bypass valve is controlled such that it decreases at a constant rate (first rate C1) with respect to the increase in the load L of gas turbine 1, as in the Fig.4. Prior art shown. On the other hand, in a case where the load L of gas turbine 1 is the second load L2 or greater and the first load is L1, the opening degree D of the bypass valve 35 is controlled such that it decreases with respect to the increase in the load L1 of gas turbine 1 at a second rate C2 that is greater than the first rate C1. In other words, in a range of 0 ≤ L ≤ L2 of the load L, the same control is carried out as in the prior art, but in a range of L2 < L ≤ L1, the opening degree D is controlled to change continuously such that the bypass valve 35 is completely closed when the load L of gas turbine 1 is the first load L1.

[0046] As described above, according to each of the embodiments described above, in a case where the mixed combustion rate R of the second fuel F2 is greater than the first threshold R1, if the mixed combustion rate R is controlled to increase with the load L of the gas turbine 1, the bypass valve 35 is controlled to be completely closed. Therefore, during mixed combustion operation, where flame flashback is likely to occur, the bypass supply of combustion air A through the bypass valve 35 is suppressed, and thus the inflow state of the main flow in the downstream space 38b of the combustion chamber 2 is stabilized. As a result, the blade channel temperature BPT does not fluctuate due to the redirected combustion air, and flame flashback can be appropriately detected based on the trend change in the blade channel temperature BPT.

[0047] Furthermore, it is possible to suitably replace the components in the embodiment described above with known components within the scope of protection, which does not deviate from the core of the present disclosure, and the embodiments described above can be suitably combined.

[0048] For example, the contents described in each of the embodiments described above are understood as follows. (1) A gas turbine control device according to one aspect is a gas turbine control device for controlling a gas turbine, comprising a combustion chamber capable of mixing with combustion air and burning a mixed fuel comprising a first fuel and a second fuel having a lower calorific value per unit volume and a faster combustion rate than the first fuel, a bypass channel capable of diverting at least a portion of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve provided in the bypass channel, wherein the gas turbine control device includes a mixed combustion rate control unit that performs control such that a mixed combustion rate of the second fuel is increased when a load on the gas turbine increases, and a bypass valve control unit.which controls the opening degree of the bypass valve based on the mixed combustion rate, wherein the bypass valve control unit controls the bypass valve so that it is fully closed in a case where the mixed combustion rate is greater than a first threshold.

[0049] According to aspect (1), if the mixed combustion rate is controlled to increase with the gas turbine load, the opening degree of the bypass valve decreases with respect to an increase in the mixed combustion rate, and the bypass valve is controlled to be fully closed at mixed combustion rates greater than the first threshold. Therefore, during mixed combustion operation, where flame flashback is likely to occur, the bypass supply of combustion air through the bypass valve is suppressed, thus stabilizing the main flow in the downstream section of the combustion chamber. As a result, the blade channel temperature does not fluctuate due to the redirected combustion air, and flame flashback can be appropriately detected based on the trend change in blade channel temperature.

[0050] (2) According to another aspect, in the above aspect (1) the first threshold is less than a maximum mixed combustion rate corresponding to a nominal operation of the gas turbine.

[0051] According to aspect (2), the first threshold, which is the minimum mixed combustion rate at which the bypass valve is controlled to be fully closed, is set to be smaller than the maximum mixed combustion rate corresponding to the rated operation of the gas turbine.

[0052] (3) According to another aspect, the first threshold for aspect (2) above is 0%.

[0053] According to aspect (3), the first threshold, which is the minimum mixed combustion rate at which the bypass valve is controlled to be fully closed, is set to 0%.

[0054] (4) According to another aspect, in one of the aspects (1) to (3) above, the bypass valve control unit controls the bypass valve in a load range greater than a first load corresponding to the first threshold in a case where the degree of opening is reduced as the load on the gas turbine increases, so that it is completely closed.

[0055] According to aspect (4), in the load range where the mixed combustion rate is greater than the first threshold, the bypass valve is controlled in a load range so that it is completely closed, so that the bypass supply of combustion air through the bypass valve can be suppressed during mixed combustion operation where flame flashback is likely to occur.

[0056] (5) According to another aspect, in the above aspect (4), the bypass valve control unit controls the opening degree of the bypass valve such that it decreases at a first rate with respect to an increase in the load of the gas turbine in a case where the load of the gas turbine is equal to or less than a second load which is less than the first load, and controls the opening degree of the bypass valve such that it decreases at a second rate which is greater than the first rate with respect to the increase in the load of the gas turbine in a case where the load of the gas turbine is the second load or greater and the first load or less.

[0057] According to aspect (5), in a range where the gas turbine load is equal to or less than the second load, the bypass valve opening rate is controlled such that it decreases with the first rate as the gas turbine load increases. Conversely, in a range where the gas turbine load is equal to or less than the second load, the bypass valve opening rate is controlled such that it decreases with the second rate, which is greater than the first rate, as the gas turbine load increases.

[0058] (6) According to another aspect, in one of the aspects (1) to (5) above, in a case where the mixed combustion rate is greater than at least the first threshold, a distribution ratio of the mixed fuel to several fuel injectors contained in the combustion chamber is changed.

[0059] According to aspect (6), if the gas turbine's mixed combustion rate exceeds the first threshold, the bypass valve is controlled to be fully closed. In this case, the deterioration in combustion efficiency can be mitigated by modifying the distribution ratio of the mixed fuel to the multiple fuel injectors provided in the combustion chamber. For example, if the gas turbine load is relatively low, the fuel injection quantity per fuel injector can be increased, and combustion efficiency can be improved by supplying the mixed fuel to some of the fuel injectors, compared to supplying the mixed fuel to all of them.

[0060] (7) According to another aspect, the gas turbine control device, in accordance with any of the aspects (1) to (6) above, further comprises a temperature sensor that detects the temperature of a combustion gas produced by the combustion chamber at a position on a downstream side of a blade of a rear turbine stage, and a flame flashback determination unit that determines the occurrence of flame flashback in the combustion chamber on the basis of the temperature.

[0061] According to aspect (7), in a case where the mixed combustion rate of the gas turbine is greater than the first threshold, the bypass valve is controlled so that it is completely closed, thus suppressing the influence of the hotspot fluctuation and enabling the determination of the occurrence of flame flashback based on the blade channel temperature to be carried out with high accuracy.

[0062] (8) A gas turbine control method according to one aspect is a gas turbine control method for controlling a gas turbine comprising a combustion chamber capable of mixing with combustion air and burning a mixed fuel comprising a first fuel and a second fuel having a lower calorific value per unit volume and a faster combustion rate than the first fuel, a bypass channel capable of diverting at least a portion of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve provided in the bypass channel, wherein the gas turbine control method includes a step of performing control such that a mixed combustion rate of the second fuel is increased when a load on the gas turbine increases.and includes a step of controlling the degree of opening of the bypass valve based on the mixed combustion rate, wherein in the step of controlling the bypass valve the bypass valve is controlled so that it is completely closed in a case where the mixed combustion rate is greater than a first threshold.

[0063] According to aspect (8), if the mixed combustion rate is controlled to increase with the gas turbine load, the bypass valve opening decreases with respect to an increase in the mixed combustion rate, and the bypass valve is controlled to be fully closed when the mixed combustion rate exceeds the first threshold. Therefore, during mixed combustion operation, where flame flashback is likely to occur, the bypass supply of combustion air through the bypass valve is suppressed, thus stabilizing the main flow in the downstream section of the combustion chamber. Consequently, the blade channel temperature does not fluctuate due to the redirected combustion air, and flame flashback can be appropriately detected based on the trend change in the blade channel temperature.

[0064] (9) A gas turbine modification method according to one aspect is a gas turbine modification method for modifying a gas turbine capable of performing a dedicated combustion operating mode in which the degree of opening of a bypass valve is controlled based on a load of the gas turbine, wherein the gas turbine comprises a combustion chamber capable of mixing a first fuel with combustion air and burning the first fuel, a bypass channel capable of diverting at least a portion of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve provided in the bypass channel, wherein the gas turbine modification method modifies a mixed combustion operating mode in which the bypass valve is controlled to be fully closed so that it is switchable to the dedicated combustion operating mode, in one case,in which a mixed fuel, containing the first fuel and a second fuel having a lower calorific value per unit volume and a faster combustion rate than the first fuel, is mixed with the combustion air in the combustion chamber and burned, and a mixed combustion rate of the second fuel is greater than a first threshold.

[0065] According to aspect (9), for example, the gas turbine, which includes the combustion chamber capable of mixing and burning (dedicated combustion) the first fuel, such as natural gas, with the combustion air, is modified to enable mixed-combustion operation. In mixed-combustion operation, in addition to the first fuel, a second fuel, such as hydrogen, which has a lower calorific value per unit volume and a faster combustion rate than the first fuel, is mixed and burned. However, the bypass valve is completely closed if the mixed-combustion rate of the second fuel exceeds the threshold of the first.Therefore, during mixed-combustion operation, where flame flashback is likely to occur, the bypass supply of combustion air through the bypass valve is suppressed. This improves and stabilizes the main flow conditions in the downstream section of the combustion chamber. Consequently, the blade channel temperature does not fluctuate due to the diverted combustion air, and flame flashback can be reliably detected based on the trend change in blade channel temperature. For example, in a gas turbine modified in this way, the dedicated combustion operating mode is executed when the second fuel cannot be supplied, while the mixed-combustion operating mode is executed when the second fuel can be supplied, allowing for selective switching of the operating mode. Reference symbol list 1 gas turbine 2 Combustion chamber 3 Compressor 6 Turbine 7 first fuel supply source 8 first fuel supply line 10 flow meters 13 Shut-off valve 14 second fuel supply source 15 flow meters 16 second fuel supply line 18 first flow control valve 22 Main fuel supply line 24 shut-off valve 25 connection point 26 second flow control valve 29 Fuel injector 30a, 30b, ... third flow control valve 31a, 31b, ... Shut-off valve 32 Inlet guide vane 34 Bypass channel 35 Bypass valve 38 Combustion chamber 38a upstream space 38b downstream space 39 cylindrical bodies 40 Temperature sensor 42 Main fuel injector 44 Pilot fuel injector 100 gas turbine control devices 102 Load sensing unit 104 Mixed combustion rate control unit 106 Bypass valve opening control unit 108 Temperature detection unit 110 Flame Backfire Determination Unit QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2023-127430

[0002] JP 2001-124338

[0005]

Claims

[1] Gas turbine control device for controlling a gas turbine, which includes: a combustion chamber capable of mixing a mixed fuel, containing a first fuel and a second fuel which has a lower calorific value per unit volume and a faster combustion rate than the first fuel, with combustion air and burning the mixed fuel, a bypass channel capable of diverting at least part of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve that is provided in the bypass channel, the gas turbine control device comprises: a mixed-combustion rate control unit that performs control such that the mixed-combustion rate of the second fuel is increased when the load on the gas turbine increases; and a bypass valve control unit that controls the opening degree of the bypass valve based on the mixed combustion rate, wherein the bypass valve control unit controls the bypass valve so that it is completely closed in a case where the mixed combustion rate is greater than a first threshold. [2] Gas turbine control device according to claim 1, wherein the first threshold is less than a maximum mixed combustion rate corresponding to a nominal operation of the gas turbine. [3] Gas turbine control device according to claim 2, wherein the first threshold is 0%. [4] Gas turbine control device according to claim 1 or 2, wherein the bypass valve control unit controls the bypass valve in a load range greater than a first load corresponding to the first threshold, in a case where the degree of opening is reduced as the load of the gas turbine increases, so that it is completely closed. [5] Gas turbine control device according to claim 4, where the bypass valve control unit controls the opening degree of the bypass valve so that it decreases at a first rate with respect to an increase in the load of the gas turbine in a case where the load of the gas turbine is equal to or less than a second load which is less than the first load, and controls the opening degree of the bypass valve so that it decreases at a second rate greater than the first rate with respect to the increase in the load of the gas turbine in a case where the load of the gas turbine is the second load or greater and the first load is less than or greater. [6] Gas turbine control device according to claim 1 or 2, wherein in a case where the mixed combustion rate is greater than at least the first threshold value, a distribution ratio of the mixed fuel to several fuel injectors contained in the combustion chamber is changed. [7] Gas turbine control device according to claim 1 or 2, further comprising: a temperature sensor that detects the temperature of combustion gas generated by the combustion chamber at a position on a downstream side of a blade of a rear turbine stage; and a flame flashback determination unit that determines the occurrence of flame flashback in the combustion chamber based on temperature. [8] Gas turbine control method for controlling a gas turbine which contains: a combustion chamber capable of mixing a mixed fuel, containing a first fuel and a second fuel which has a lower calorific value per unit volume and a faster combustion rate than the first fuel, with combustion air and burning the mixed fuel, a bypass channel capable of diverting at least part of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve that is provided in the bypass channel, the gas turbine control procedure includes: a step of implementing control such that a mixed combustion rate of the second fuel is increased when the load on the gas turbine increases; and a step of controlling the opening degree of the bypass valve based on the mixed combustion rate, wherein in the step of controlling the bypass valve, the bypass valve is controlled so that it is completely closed in a case where the mixed combustion rate is greater than a first threshold. [9] Gas turbine modification method for modifying a gas turbine capable of performing a dedicated combustion operating mode in which the opening degree of a bypass valve is controlled based on a load of the gas turbine, wherein the gas turbine includes: a combustion chamber capable of mixing a primary fuel with combustion air and burning the primary fuel, a bypass channel capable of diverting at least part of the combustion air and supplying it to a downstream space of the combustion chamber, and a bypass valve that is provided in the bypass channel, the gas turbine modification procedure includes: Modifying a mixed combustion operating mode in which the bypass valve is controlled to be fully closed so that it is switchable to the dedicated combustion operating mode, in a case where a mixed fuel containing the first fuel and a second fuel having a lower calorific value per unit volume and a faster combustion rate than the first fuel is mixed with the combustion air in the combustion chamber and is burned, and a mixed combustion rate of the second fuel is greater than a first threshold.

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