Fuel control device, fuel control method, and program

Abstract

According to the present invention: when first fuel gas is supplied by a fuel supply system, a mass flow rate of the first fuel gas for each fuel supply system is calculated on the basis of a fuel flow rate command value for bringing a gas turbine into a desired operation state and a fuel distribution ratio for each fuel supply system; a mixed gas calorie ratio, which is the ratio between the calorie of mixed gas obtained by mixing the first fuel gas and second fuel gas and the calorie of the first fuel gas, is calculated; a mass flow rate of the mixed gas when the mixed gas is supplied by the fuel supply system instead of the first fuel gas is calculated on the basis of the mass flow rate of the first fuel gas for each fuel supply system and the mixed gas calorie ratio; a volume flow rate for each fuel supply system is calculated on the basis of the mass flow rate of the mixed gas for each fuel supply system and the density of the mixed gas; and a valve opening degree of a flow rate control valve for each fuel supply system is calculated from the volume flow rate for each fuel supply system.

Description

Fuel control device, fuel control method, and program

[0001] This application claims priority to Japanese Patent Application No. 2024-150220, filed on August 30, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, with the aim of achieving decarbonization, a mixed gas obtained by mixing hydrogen gas, which does not emit CO2, with natural gas, which is the main fuel for gas turbines, has been used as the fuel for gas turbines. When a mixed gas obtained by mixing multiple gases is used as the fuel for a gas turbine in this way, the density and calories of the fuel differ from when only the main fuel is used, and therefore corrections are made to the control of the gas turbine in accordance with this difference (see, for example, Patent Document 1).

[0003] JP 2012-140896 A

[0004] Incidentally, a control system of a gas turbine uses a signal called a CSO (Control Signal Output), and the flow rate of fuel supplied to the gas turbine is adjusted by increasing or decreasing a fuel flow rate command value, which is a value indicated by this CSO signal.

[0005] At present, gas turbine control systems are not designed to use mixed gas as fuel, and control systems designed to use natural gas as fuel are used in situations where mixed gas is used as fuel. Therefore, the fuel flow rate derived from the fuel flow command value indicates the flow rate of natural gas, and this flow rate cannot be used as is for mixed gas, which has a different density and calorie from natural gas.

[0006] On the other hand, the fuel flow rate command value is not only referenced when adjusting the fuel flow rate, but also referenced in various control operations in the gas turbine. Some control operations that reference the fuel flow rate command value are performed on the assumption that, for example, a change in the fuel flow rate command value and a change in the power generation amount (hereinafter also referred to as MW (Megawatt)) of the gas turbine have a fixed relationship. Therefore, if the fuel flow rate command value is changed to a value that can derive the flow rate of the mixed gas, the relationship between the change in the fuel flow rate command value and the change in MW will change. If this relationship changes, some kind of change will be required to all control operations that are performed on the assumption that this relationship is fixed.

[0007] The present disclosure has been made in consideration of the above circumstances, and aims to provide a fuel control device, a fuel control method, and a program that can supply a mixed gas at an appropriate flow rate to a gas turbine without changing a fuel flow rate command value.

[0008] In order to solve the above problems, a fuel control device according to the present disclosure includes: a mass flow rate calculating unit that calculates a mass flow rate of the first fuel gas for each fuel supply system, based on a fuel flow rate command value that brings a gas turbine into a desired operating state when a first fuel gas is supplied through the fuel supply system and a fuel allocation ratio for each of the fuel supply systems; a mixed gas calorie ratio calculating unit that calculates a mixed gas calorie ratio that is a ratio of a calorie of the first fuel gas to a calorie of a mixed gas obtained by mixing the first fuel gas and a second fuel gas; a mixed gas mass flow rate calculating unit that calculates a mass flow rate of the mixed gas when the mixed gas is supplied through the fuel supply system in place of the first fuel gas, based on each of the mass flow rates of the first fuel gas for each of the fuel supply systems and the mixed gas calorie ratio; a volumetric flow rate calculating unit that calculates a volumetric flow rate for each of the fuel supply systems based on each of the mass flow rates of the mixed gas for each of the fuel supply systems and a density of the mixed gas; and a valve aperture calculating unit that calculates a valve aperture of a flow rate control valve for each of the fuel supply systems from each of the volumetric flow rates for each of the fuel supply systems.

[0009] A fuel control method according to the present disclosure calculates a mass flow rate of the first fuel gas for each fuel supply system based on a fuel flow rate command value that brings a gas turbine into a desired operating state when a first fuel gas is supplied through the fuel supply system and on a fuel allocation ratio for each of the fuel supply systems; calculates a mixed gas calorie ratio that is a ratio of a calorie of the first fuel gas to a calorie of a mixed gas obtained by mixing the first fuel gas and a second fuel gas; calculates a mass flow rate of the mixed gas when the mixed gas is supplied through the fuel supply system in place of the first fuel gas, based on each of the mass flow rates of the first fuel gas for each fuel supply system and the mixed gas calorie ratio; calculates a volumetric flow rate for each of the fuel supply systems based on each of the mass flow rates of the mixed gas for each fuel supply system and a density of the mixed gas; and calculates a valve aperture of a flow rate control valve for each of the fuel supply systems from each of the volumetric flow rates for each of the fuel supply systems.

[0010] A program according to the present disclosure is a program that causes a computer to function as: mass flow rate calculating means that calculates a mass flow rate of the first fuel gas for each fuel supply system, based on a fuel flow rate command value that brings a gas turbine into a desired operating state when a first fuel gas is supplied through the fuel supply system and on a fuel allocation ratio for each of the fuel supply systems; mixed gas calorie ratio calculating means that calculates a mixed gas calorie ratio that is a ratio of a calorie of the first fuel gas to a calorie of a mixed gas obtained by mixing the first fuel gas and a second fuel gas; mixed gas mass flow rate calculating means that calculates a mass flow rate of the mixed gas when the mixed gas is supplied through the fuel supply system instead of the first fuel gas, based on each of the mass flow rates of the first fuel gas for each of the fuel supply systems and the mixed gas calorie ratio; volumetric flow rate calculating means that calculates a volumetric flow rate for each of the fuel supply systems, based on each of the mass flow rates of the mixed gas for each of the fuel supply systems and the density of the mixed gas; and valve aperture calculating means that calculates a valve aperture of a flow rate control valve for each of the fuel supply systems from each of the volumetric flow rates for each of the fuel supply systems.

[0011] According to the fuel control device, fuel control method, and program of the present disclosure, it is possible to supply a mixed gas at an appropriate flow rate to a gas turbine without changing the fuel flow rate command value.

[0012] Fig. 1 is a block diagram showing an example configuration of a gas turbine power plant according to an embodiment of the present disclosure; Fig. 2 is a block diagram showing an example internal configuration of a fuel control device according to an embodiment of the present disclosure and an example connection configuration of devices, etc. connected to the fuel control device; Fig. 3 is a diagram showing an example of values ​​stored in a storage unit according to an embodiment of the present disclosure; Fig. 4 is a flowchart showing an example operation of a fuel control device according to an embodiment of the present disclosure; Fig. 5 is a diagram (part 1) showing an example calculation by a fuel control device according to an embodiment of the present disclosure; Fig. 6 is a diagram (part 2) showing an example calculation by a fuel control device according to an embodiment of the present disclosure; Fig. 7 is a schematic block diagram showing the configuration of a computer according to at least one embodiment;

[0013] Hereinafter, a fuel control device, a fuel control method, and a program according to an embodiment of the present disclosure will be described with reference to the drawings. Note that the same or corresponding components in the drawings will be denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0014] 1 is a block diagram showing an example of the configuration of a gas turbine power plant 1 according to an embodiment of the present disclosure. The gas turbine power plant 1 includes a gas turbine 2, a natural gas fuel supply line 3, a hydrogen gas fuel supply line 4, a mixed gas fuel supply line 5, a fuel control device 6, a fuel supply line connection unit 10, a wattmeter 11, a thermometer 12, a pressure gauge 13, and a CSO signal output device 14.

[0015] The fuel supply line connection unit 10 is a three-way joint that connects the piping of three fuel supply lines, for example, the natural gas fuel supply line 3, the hydrogen gas fuel supply line 4, and the mixed gas fuel supply line 5. At the fuel supply line connection unit 10, natural gas flows in from the natural gas fuel supply line 3, hydrogen gas flows in from the hydrogen gas fuel supply line 4, and a mixed gas of natural gas and hydrogen gas flows out to the mixed gas fuel supply line 5.

[0016] The natural gas fuel supply line 3 includes a natural gas supply source 31, a compressor 32, and a natural gas measurement unit 33. Pipes are connected between the natural gas supply source 31 and the compressor 32, between the compressor 32 and the natural gas measurement unit 33, and between the natural gas measurement unit 33 and the fuel supply line connection unit 10. Natural gas supplied from the natural gas supply source 31 is compressed by the compressor 32, and the compressed natural gas flows into the fuel supply line connection unit 10 via the natural gas measurement unit 33.

[0017] The hydrogen gas fuel supply line 4 includes a hydrogen gas supply source 41, a hydrogen gas measurement unit 42, and a hydrogen gas flow rate control valve 43. Pipes connect the hydrogen gas supply source 41 and the hydrogen gas measurement unit 42, the hydrogen gas measurement unit 42 and the hydrogen gas flow rate control valve 43, and the hydrogen gas flow rate control valve 43 and the fuel supply line connection unit 10. Hydrogen gas supplied from the hydrogen gas supply source 41 flows into the hydrogen gas flow rate control valve 43 via the hydrogen gas measurement unit 42. Hydrogen gas flows out of the hydrogen gas flow rate control valve 43 at a flow rate corresponding to the valve opening of the hydrogen gas flow rate control valve 43 and flows into the fuel supply line connection unit 10. When the hydrogen gas flow rate control valve 43 receives a signal including the valve opening from the fuel control device 6, it opens or closes the valve to the valve opening included in the received signal.

[0018] Each of the natural gas measurement unit 33 and the hydrogen gas measurement unit 42 includes, for example, a flowmeter that measures the volumetric flow rate of the fluid passing therethrough, a pressure gauge that measures the pressure of the fluid at the inlet of the flowmeter, and a thermometer that measures the temperature of the fluid at the outlet of the flowmeter. The natural gas measurement unit 33 performs measurements, for example, at regular intervals, and outputs measurement data including the volumetric flow rate of natural gas output by the flowmeter, the pressure value of natural gas output by the pressure gauge, and the temperature value of natural gas output by the thermometer to the fuel control device 6. The hydrogen gas measurement unit 42 performs measurements repeatedly, for example, at regular intervals, and outputs measurement data including the volumetric flow rate of hydrogen gas output by the flowmeter, the pressure value of hydrogen gas output by the pressure gauge, and the temperature value of hydrogen gas output by the thermometer to the fuel control device 6.

[0019] The mixed gas fuel supply line 5 includes three fuel supply systems to the gas turbine 2: a top hat fuel supply system 5-T, a pilot fuel supply system 5-P, and a main fuel supply system 5-M. The mixed gas fuel supply line 5 includes an inlet pipe 51, flow rate control valves 52T, 52P, and 52M, and outlet pipes 53T, 53P, and 53M. One end of the inlet pipe 51 is connected to the fuel supply line connection unit 10, and the three other ends are connected to one end of each of the flow rate control valves 52T, 52P, and 52M. The inlet pipe 51 branches the mixed gas flowing in from the fuel supply line connection unit 10 into three directions.

[0020] The mixed gases branched by the inlet pipe 51 flow into flow rate control valves 52T, 52P, and 52M. The other ends of the flow rate control valves 52T, 52P, and 52M are connected to outlet pipes 53T, 53P, and 53M, respectively. The mixed gases at flow rates corresponding to the valve apertures of the flow rate control valves 52T, 52P, and 52M flow out from the other ends of the flow rate control valves 52T, 52P, and 52M and are supplied to the gas turbine 2 via the outlet pipes 53T, 53P, and 53M. When the flow rate control valves 52T, 52P, and 52M receive a signal including the valve aperture from the fuel control device 6, they open or close the valves to the valve apertures included in the received signal.

[0021] Top hat fuel supply system 5-T is a portion of the piping after inlet piping 51 branches, and includes a portion of the piping that connects to flow rate control valve 52T, flow rate control valve 52T, and outlet piping 53T. Pilot fuel supply system 5-P is a portion of the piping after inlet piping 51 branches, and includes a portion of the piping that connects to flow rate control valve 52P, flow rate control valve 52P, and outlet piping 53P. Main fuel supply system 5-M is a portion of the piping after inlet piping 51 branches, and includes a portion of the piping that connects to flow rate control valve 52M, flow rate control valve 52M, and outlet piping 53M.

[0022] 1 shows the main components of the natural gas fuel supply line 3, the hydrogen gas fuel supply line 4, and the mixed gas fuel supply line 5. In practice, a heater may be inserted between the natural gas measurement unit 33 of the natural gas fuel supply line 3 and the fuel supply line connection unit 10, and shut-off valves or the like may be inserted at various locations in the natural gas fuel supply line 3, the hydrogen gas fuel supply line 4, and the mixed gas fuel supply line 5.

[0023] The gas turbine 2 includes an air compressor 21, a combustor 22, a turbine 23, a rotor 24, and a generator 25. The air compressor 21 takes in and compresses air through the rotation of the rotor 24, which passes through the air compressor 21, the combustor 22, and the turbine 23, and supplies the compressed air to the combustor 22. The combustor 22 includes three fuel injectors: a top hat fuel injector, a pilot fuel injector, and a main fuel injector. The top hat fuel injector receives mixed gas from an outlet pipe 53T of a top hat fuel supply system 5-T. The pilot fuel injector receives mixed gas from an outlet pipe 53P of a pilot fuel supply system 5-P. The main fuel injector receives mixed gas from an outlet pipe 53M of a main fuel supply system 5-M.

[0024] In the combustor 22, the top hat fuel injector, pilot fuel injector, and main fuel injector inject mixed gas into air supplied from the air compressor 21, and the mixed gas is burned. Combustion gas generated by the combustion of the mixed gas flows into the turbine 23, causing the rotor 24 to rotate, and the rotation of the rotor 24 generates electricity in the generator 25.

[0025] The thermometer 12 measures, for example, at regular intervals, the temperature of the mixed gas passing through the inlet pipe 51 before it branches into three ways, and outputs the measured temperature value of the mixed gas to the fuel control device 6. The pressure gauge 13 measures, for example, at regular intervals, the pressure of the mixed gas passing through the inlet pipe 51 before it branches into three ways, and outputs the measured pressure value of the mixed gas to the fuel control device 6. The power meter 11 measures, for example, at regular intervals, the power generated by the generator 25, and outputs the measured power value to the CSO signal output device 14.

[0026] For example, each time the CSO signal output device 14 receives a power value output by the power meter 11, the CSO signal output device 14 calculates a fuel flow rate command value that brings the amount of power generated by the generator 25 closer to the target power value, based on the difference between the received power value and an externally provided target power value. The CSO signal output device 14 generates a CSO signal that represents the calculated fuel flow rate command value, and outputs the generated CSO signal to the fuel control device 6.

[0027] (Configuration of fuel control device) The fuel control device 6 can be configured using, for example, a computer such as a server, a personal computer, or a microcomputer, and peripheral devices of that computer, and is equipped with a hydrogen gas valve opening calculation unit 61, a memory unit 62, a mass flow rate calculation unit 63, a mixed gas calorie ratio calculation unit 64, a mixed gas mass flow rate calculation unit 65, a volumetric flow rate calculation unit 66, and a valve opening calculation unit 67 as functional configurations formed by a combination of hardware of the computer or the like and software such as a program executed by the computer, as shown in FIG. 2 .

[0028] The memory unit 62 stores the values ​​shown in Figure 3. The natural gas LHV (Lower Heating Value) is a value that represents the amount of heat, i.e., calories, obtained from 1 kg of natural gas. The hydrogen gas LHV is a value that represents the calories obtained from 1 kg of hydrogen gas. The unit of the natural gas LHV and hydrogen gas LHV is [kcal / kg]. The hydrogen mass mixing ratio is expressed as a numerical value that represents the proportion of hydrogen gas contained in the mixed gas in terms of mass, in other words, the mass of hydrogen gas contained in a unit mass of the mixed gas.

[0029] The air density, natural gas density, and hydrogen gas density are the densities of air, natural gas, and hydrogen gas, respectively, under reference conditions, and are expressed in units of kg / Nm3. Here, the reference conditions are defined as a state in which the temperature is 0°C, the pressure is 1 atm, and the gas is dry. The calculation constants include five calculation constants SG1, SG2, SG3, SG4, and SG5, where SG1 = 1, SG2 = 3600, SG3 = 0.258, SG4 = 273, and SG5 = 289.

[0030] Values ​​other than the hydrogen mass mixing ratio are pre-recorded in the storage unit 62. After an initial value for the hydrogen mass mixing ratio is pre-recorded in the storage unit 62, it may be rewritten externally when a change is required during operation of the gas turbine 2, for example.

[0031] Mass flow rate calculation unit 63 takes in the CSO signal output by CSO signal output device 14 and the fuel distribution ratio that is continuously supplied from the outside. Here, the fuel distribution ratio is a ratio in which the amounts distributed to each of the top hat fuel supply system 5-T, the pilot fuel supply system 5-P, and the main fuel supply system 5-M are expressed as three values ​​in the unit of [%], and the sum of the three values ​​is 100 [%]. Hereinafter, the expression "each of the top hat fuel supply system 5-T, the pilot fuel supply system 5-P, and the main fuel supply system 5-M" will be abbreviated as "each of the fuel supply systems" or "each fuel supply system."

[0032] The fuel allocation ratio is a ratio that changes depending on the operating state of the gas turbine 2. For example, different fuel allocation ratios are selected by the operator of the gas turbine power plant 1 for ignition and for rated load operation, and are supplied to the mass flow calculation unit 63. The mass flow calculation unit 63 calculates the mass flow rate of natural gas corresponding to each fuel supply system based on the fuel flow command value indicated by the CSO signal and the fuel allocation ratio.

[0033] The mixed gas calorie ratio calculation unit 64 calculates the mixed gas calorie ratio, which is the ratio of the calories of the mixed gas to the calories of the natural gas, based on the natural gas LHV, hydrogen gas LHV, and hydrogen mass mixing ratio stored in the memory unit 62.

[0034] The mixed gas mass flow rate calculation unit 65 calculates the mass flow rate of the mixed gas when the mixed gas is supplied through each fuel supply system instead of natural gas, based on each mass flow rate of natural gas for each fuel supply system and the mixed gas calorie ratio.

[0035] The volumetric flow rate calculation unit 66 calculates the mixed gas density based on the hydrogen mass mixing ratio, natural gas density, and hydrogen gas density stored in the memory unit 62. The volumetric flow rate calculation unit 66 calculates the volumetric flow rate of the mixed gas for each fuel supply system based on each of the mass flow rates of the mixed gas for each fuel supply system and the calculated mixed gas density.

[0036] The valve opening calculation unit 67 calculates the valve opening of each of the flow rate control valves 52T, 52P, 52M based on the mixed gas density, the air density stored in the memory unit 62, the temperature and pressure of the mixed gas in the actual environment, and the volumetric flow rate of the mixed gas for each fuel supply system. Here, the temperature of the mixed gas in the actual environment is the temperature measured by the thermometer 12, and the pressure of the mixed gas in the actual environment is the pressure measured by the pressure gauge 13.

[0037] The hydrogen gas valve opening calculation unit 61 adjusts the valve opening of the hydrogen gas flow control valve 43 based on the measurement data output by each of the natural gas measurement unit 33 and the hydrogen gas measurement unit 42 so that the mixed gas supplied to the gas turbine 2 maintains the hydrogen mass mixture ratio stored in the memory unit 62.

[0038] (Processing by Fuel Control Device) The processing by the fuel control device 6 will be described with reference to Figures 4 to 6. Figure 4 is a flowchart showing the flow of processing by the fuel control device 6. Note that in parallel with the processing of the flowchart shown in Figure 4, processing by the hydrogen gas valve opening degree calculation unit 61, which will be described below, is performed.

[0039] The hydrogen gas valve opening calculation unit 61 takes in the measurement data output by the natural gas measurement unit 33 and the hydrogen gas measurement unit 42. The hydrogen gas valve opening calculation unit 61 calculates the hydrogen mass mixing ratio based on actual measurements, based on the volumetric flow rate, pressure value, and temperature value of natural gas and the volumetric flow rate, pressure value, and temperature value of hydrogen gas contained in the two pieces of measurement data taken in, and the natural gas density and hydrogen gas density stored in the memory unit 62.

[0040] The hydrogen gas valve opening calculation unit 61 calculates the volumetric flow rate of hydrogen gas that brings the hydrogen mass mixing ratio based on actual measurement closer to the hydrogen mass mixing ratio stored in the memory unit 62. The hydrogen gas valve opening calculation unit 61 calculates the valve opening that will allow hydrogen gas to flow at the calculated volumetric flow rate. The hydrogen gas valve opening calculation unit 61 outputs a signal including the calculated valve opening to the hydrogen gas flow rate adjustment valve 43. In response to this signal, the hydrogen gas flow rate adjustment valve 43 opens or closes the valve to the valve opening included in the signal.

[0041] The natural gas measurement unit 33 and the hydrogen gas measurement unit 42 perform measurements at regular intervals, and each time a measurement is performed, the measurement data is output to the hydrogen gas valve opening calculation unit 61. Each time the hydrogen gas valve opening calculation unit 61 receives measurement data output by the natural gas measurement unit 33 and the hydrogen gas measurement unit 42, it calculates a new valve opening and outputs it to the hydrogen gas flow rate control valve 43. This adjusts the flow rate of hydrogen gas so that the proportion of hydrogen gas contained in the mixed gas flowing from the fuel supply line connection unit 10 to the inlet pipe 51 is maintained at the hydrogen mass mixing ratio.

[0042] The processing shown in Fig. 4 will be described below. In Fig. 4, processing S1-1 is performed each time the mass flow calculation unit 63 receives the CSO signal output by the CSO signal output device 14. Processing S1-2 and S1-3 are performed each time the hydrogen mass mixing ratio is recorded in the storage unit 62. Processing S1-4 is performed each time the valve opening calculation unit 67 receives the temperature value output by the thermometer 12 and the pressure value output by the pressure gauge 13. Note that the initial value of the hydrogen mass mixing ratio is recorded in the storage unit 62 before the initial processing of S1-1 and S1-4 is performed, and therefore the initial processing of S1-2 and S1-3 is performed before the initial processing of S1-1 and S1-4.

[0043] Here, it is assumed that the frequency at which the CSO signal output device 14 outputs the CSO signal is approximately the same as the frequency at which the thermometer 12 and the pressure gauge 13 output their respective measurement values, that is, the temperature value and the pressure value. It is also assumed that the frequency at which the hydrogen mass mixing ratio stored in the storage unit 62 is updated is less than the frequency at which the CSO signal output device 14 outputs the CSO signal and the frequency at which the thermometer 12 and the pressure gauge 13 output their respective measurement values, that is, the temperature value and the pressure value.

[0044] (Processing of S1-1) As shown in FIG. 5 , the mass flow rate calculation unit 63 includes a multiplier 131 and a function calculator 132. The multiplier 131 takes in the CSO signal output by the CSO signal output device 14 and the fuel allocation ratio that is continuously supplied from the outside. Here, assume that the fuel flow rate command value indicated by the CSO signal is, for example, "80," and the fuel allocation ratios are 5% for the top hat fuel supply system 5-T, 15% for the pilot fuel supply system 5-P, and 80% for the main fuel supply system 5-M. In this case, the multiplier 131 calculates the following values: 80×5%=4 for the top hat fuel supply system 5-T, 80×15%=12 for the pilot fuel supply system 5-P, and 80×80%=64 for the main fuel supply system 5-M. The multiplier 131 outputs the three calculated values ​​“4”, “12”, and “64” to the function calculator 132 .

[0045] The function calculator 132 calculates a function (hereinafter referred to as a CSO / natural gas required mass flow rate conversion function (FX1)) that calculates the total mass flow rate of natural gas when natural gas is supplied to the gas turbine 2, from the fuel flow rate command value indicated by the CSO signal. The function calculator 132 takes in the three values ​​"4," "12," and "64" output by the multiplier 131, and substitutes each of the three values ​​"4," "12," and "64" into the CSO / natural gas required mass flow rate conversion function (FX1). The three values ​​obtained by this substitution become the mass flow rate of natural gas supplied by the top hat fuel supply system 5-T, the mass flow rate of natural gas supplied by the pilot fuel supply system 5-P, and the mass flow rate of natural gas supplied by the main fuel supply system 5-M, all expressed in the unit of kg / s. The function calculator 132 outputs the mass flow rate of natural gas for each fuel supply system to the mixed gas mass flow rate calculation unit 65.

[0046] (Processing of S1-2) As shown in FIG. 5 , the mixed gas calorific ratio calculation unit 64 includes multipliers 141 and 143, a subtractor 142, an adder 144, and a divider 145. When the multiplier 141 detects that a hydrogen mass mixing ratio has been recorded in the memory unit 62, it reads the hydrogen mass mixing ratio and the hydrogen gas LHV from the memory unit 62, multiplies the hydrogen mass mixing ratio by the hydrogen gas LHV, and outputs the multiplied value obtained by the multiplication to the adder 144. When the subtractor 142 detects that a hydrogen mass mixing ratio has been recorded in the memory unit 62, it reads the hydrogen mass mixing ratio and a calculation constant SG1 (=1) from the memory unit 62 and subtracts the hydrogen mass mixing ratio from the calculation constant SG1. Because the hydrogen mass mixing ratio is a numerical value indicating the mass of hydrogen gas contained in a unit mass of the mixed gas, the subtracted value obtained by this subtraction is a numerical value indicating the mass of natural gas contained in a unit mass of the mixed gas. The subtractor 142 outputs the subtracted value to the multiplier 143. When the multiplier 143 receives the subtracted value output by the subtractor 142, it reads the natural gas LHV from the memory unit 62. The multiplier 143 multiplies the subtracted value by the natural gas LHV and outputs the multiplied value obtained by the multiplication to the adder 144.

[0047] Adder 144 takes in the multiplied value output by multiplier 141 and the multiplied value output by multiplier 143, adds the two taken in multiplied values, and outputs the sum obtained by the addition to divider 145. When divider 145 takes in the sum output by adder 144, it reads the natural gas LHV from memory unit 62 and divides the sum by the natural gas LHV.

[0048] Here, the multiplied value output by multiplier 141 indicates the calories of hydrogen gas contained in unit mass of mixed gas, and the multiplied value output by multiplier 143 indicates the calories of natural gas contained in unit mass of mixed gas. Therefore, the added value output by adder 144 is the calories of unit mass of mixed gas. As described above, the natural gas LHV is the calories of unit mass of natural gas. Therefore, the divided value obtained by division by divider 145 is the value obtained by dividing the calories of unit mass of mixed gas by the calories of unit mass of natural gas, and this value is the value of the mixed gas calorie ratio described above. Divider 145 outputs the calculated value of the mixed gas calorie ratio to the mixed gas mass flow rate calculation unit 65 (S1-2).

[0049] (Processing of S2) The processing of S2, which is performed after the processing of S1-1 and S1-2, will be described. As shown in FIG. 5, the mixed gas mass flow rate calculation unit 65 includes a divider 151. The processing of S1-2 is performed less frequently than the processing of S1-1. Therefore, when the divider 151 receives the value of the mixed gas caloric ratio output by the divider 145 of the mixed gas caloric ratio calculation unit 64, it records the received value of the mixed gas caloric ratio in an internal storage area. If the previous value of the mixed gas caloric ratio is stored in the internal storage area, the divider 151 deletes the previous value of the mixed gas caloric ratio and records the received value of the mixed gas caloric ratio, thereby updating the value of the mixed gas caloric ratio stored in the internal storage area.

[0050] The divider 151 takes in the mass flow rate of natural gas for each fuel supply system output by the function calculator 132, and divides each of the taken-in mass flow rates of natural gas for each fuel supply system by the value of the mixed gas calorie ratio stored in an internal memory area.

[0051] Comparing the properties of natural gas and hydrogen gas, the two fuel gases have the following differences in properties. Hydrogen gas has a higher combustion rate than natural gas. Hydrogen gas has a lower calorie content per unit volume than natural gas, but a higher calorie content per unit mass. Therefore, the calorie content of a unit mass of mixed gas is greater than the calorie content of a unit mass of natural gas, and the value of the mixed gas calorie ratio, calculated by dividing the calorie content of a unit mass of mixed gas by the calorie content of a unit mass of natural gas, is greater than "1."

[0052] Therefore, the calculation performed by divider 151 of dividing each mass flow rate of natural gas for each fuel supply system by the value of the mixed gas calorie ratio, which is a value greater than "1," is a calculation of calculating the mass flow rate of mixed gas that supplies the same calories as when natural gas is supplied, when the supplied fuel gas is replaced from natural gas to mixed gas. Divider 151 outputs the calculated mass flow rate of mixed gas for each fuel supply system to volumetric flow rate calculation unit 66.

[0053] 5, the volumetric flow rate calculation unit 66 includes dividers 161, 163, 166, a subtractor 162, an adder 164, a reciprocal calculator 165, and a multiplier 167. When the divider 161 detects that the hydrogen mass mixing ratio has been recorded in the memory unit 62, it reads out the hydrogen mass mixing ratio and the hydrogen gas density from the memory unit 62. The divider 161 divides the hydrogen mass mixing ratio by the hydrogen gas density, and outputs the divided value obtained by the division to the adder 164.

[0054] When the subtractor 162 detects that the hydrogen mass mixing ratio has been recorded in the memory unit 62, it reads out the hydrogen mass mixing ratio and the calculation constant SG1 (=1) from the memory unit 62. The subtractor 162 subtracts the hydrogen mass mixing ratio from the calculation constant SG1. The subtraction value obtained by this subtraction is a numerical value indicating the mass of natural gas contained in unit mass of the mixed gas. The subtractor 162 outputs the subtraction value to the divider 163. The divider 163 takes in the subtraction value output by the subtractor 162 and reads out the natural gas density from the memory unit 62. The divider 163 divides the subtraction value by the natural gas density and outputs the divided value obtained by the division to the adder 164.

[0055] Adder 164 takes in the divided value output by divider 161 and the divided value output by divider 163, and adds the two taken in divided values. Adder 164 outputs the calculated sum to reciprocal calculator 165. Reciprocal calculator 165 takes in the sum output by adder 164, and calculates the reciprocal of the taken in sum.

[0056] The divided value output by the divider 161 is the mass of hydrogen gas contained in a unit mass of mixed gas divided by the hydrogen gas density, and therefore calculates the volume of hydrogen gas contained in a unit mass of mixed gas. The divided value output by the divider 163 is the mass of natural gas contained in a unit mass of mixed gas divided by the natural gas density, and therefore calculates the volume of natural gas contained in a unit mass of mixed gas. Therefore, the sum calculated by the adder 164 is the volume of hydrogen gas and the volume of natural gas contained in a unit mass of mixed gas, i.e., the volume of the mixed gas per unit mass. Therefore, the reciprocal of the sum calculated by the reciprocal calculator 165 is the mass of the mixed gas per unit volume, i.e., the mixed gas density [kg / Nm3]. The reciprocal calculator 165 outputs the calculated mixed gas density to the divider 166 and the valve opening calculation unit 67.

[0057] (Processing of S3-1) The frequency with which processing of S1-3 is performed is less than the frequency with which processing of S2 is performed. Therefore, when divider 166 takes in the mixed gas density output by reciprocal calculator 165, it records the taken-in mixed gas density in an internal storage area. If the previous mixed gas density is stored in the internal storage area, divider 166 deletes the previous mixed gas density and records the taken-in mixed gas density, so that the mixed gas density stored in the internal storage area is updated to the latest state.

[0058] Divider 166 receives the mass flow rate of the mixed gas for each fuel supply system output by divider 151 of mixed gas mass flow calculation unit 65, divides each of the received mass flow rates of the mixed gas for each fuel supply system by the mixed gas density stored in an internal storage area, and outputs the volumetric flow rate of the mixed gas for each fuel supply system calculated by this division to multiplier 167.

[0059] The multiplier 167 takes in the volumetric flow rate of the mixed gas for each fuel supply system output by the divider 166 and reads out the calculation constant SG2 (=3600) from the storage unit 62. The multiplier 167 multiplies the volumetric flow rate of the mixed gas for each fuel supply system by the calculation constant SG2. The volumetric flow rate of the mixed gas for each fuel supply system output by the divider 166 is a volumetric flow rate per second, with units of [Nm3 / s]. Therefore, the multiplier 167 multiplies this by the calculation constant SG2 of "3600" to convert it into a volumetric flow rate per hour. The multiplier 167 outputs the calculated multiplied value, the volumetric flow rate of the mixed gas for each fuel supply system [Nm3 / h], to the valve opening calculation unit 67.

[0060] 6, the valve opening degree calculation unit 67 includes dividers 171, 174, and 176, multipliers 172, 175, and 178, an adder 173, a square root calculator 177, and a function calculator 179. The calculations performed by the dividers 171, 174, and 176, the multipliers 172, 175, and 178, the adder 173, and the square root calculator 177 are calculations for calculating the volume Cg passing through the valve, which is expressed by the following equation (1).

[0061]

[0062] In equation (1), Q is the volumetric flow rate [Nm3 / h], G is the gas specific gravity, P1 is the valve inlet fluid pressure [MPaA], and T1 is the valve inlet fluid temperature [°C].

[0063] The divider 171 receives a pressure value (hereinafter referred to as pressure value P1) output by the pressure gauge 13 and substituted for P1 in equation (1). The divider 171 reads a calculation constant SG3 (=0.258) from the storage unit 62, divides the calculation constant SG3 by the pressure value P1, and outputs the divided value obtained by the division to the multiplier 172. The adder 173 receives a temperature value (hereinafter referred to as temperature value T1) output by the thermometer 12 and substituted for T1 in equation (1). The adder 173 reads a calculation constant SG4 (=273) from the storage unit 62, adds the calculation constant SG4 to the temperature value T1, and outputs the sum obtained by the addition to the multiplier 175. The calculation by the adder 173 converts the temperature value T1, which is expressed in units of °C, into units of K.

[0064] (Processing of S3-2) Divider 174 takes in the mixed gas density output by reciprocal calculator 165 of volumetric flow rate calculation unit 66 in processing of S1-3. Divider 174 reads the air density from storage unit 62 and divides the mixed gas density by the air density to calculate the mixed gas specific gravity (hereinafter referred to as mixed gas specific gravity G) represented by G in equation (1). Divider 174 outputs the calculated mixed gas specific gravity G to multiplier 175.

[0065] (Processing of S4) The frequency with which the processing of S3-1 is performed is equal to or less than the frequency with which the processing of S1-4 is performed. Therefore, the multiplier 172 performs the following process so that the latest pressure value is reflected in the calculation result. When the multiplier 172 receives the volumetric flow rate [Nm3 / h] of the mixed gas for each fuel supply system output by the multiplier 167 of the volumetric flow rate calculation unit 66 in the processing of S3-1, the multiplier 172 waits for the divider 171 to output the division value "0.258 / P1." When the divider 171 outputs the division value "0.258 / P1," the multiplier 172 receives the output division value "0.258 / P1" and multiplies each of the received volumetric flow rates [Nm3 / h] of the mixed gas for each fuel supply system by the division value "0.258 / P1." Since each volumetric flow rate [Nm3 / h] of the mixed gas for each fuel supply system is Q in equation (1), each multiplied value for each fuel supply system obtained by multiplication in multiplier 172 is the value calculated by "0.258 x Q / P1" on the right side of equation (1). Multiplier 172 outputs each multiplied value for each fuel supply system to multiplier 178.

[0066] The frequency with which the process of S3-2 is performed is less than the frequency with which the process of S1-4 is performed. Therefore, when the multiplier 175 receives the mixed gas specific gravity G output by the divider 174 in the process of S3-2, the multiplier 175 records the received mixed gas specific gravity G in an internal storage area. If the previous mixed gas specific gravity G is stored in the internal storage area, the multiplier 175 deletes the previous mixed gas specific gravity G and records the received mixed gas specific gravity G, so that the mixed gas specific gravity G stored in the internal storage area is updated to the latest value.

[0067] The multiplier 175 takes in the sum "273+T1" output by the adder 173 in the process of S1-4, and multiplies the taken-in sum "273+T1" by the mixed gas specific gravity G stored in an internal storage area. The multiplier 175 outputs the multiplied value "G(273+T1)" obtained by this multiplication to the divider 176. The divider 176 takes in the multiplied value "G(273+T1)" output by the multiplier 175, and reads out the calculation constant SG5 (=289) from the storage unit 62. The divider 176 divides the multiplied value "G(273+T1)" by the calculation constant SG5, and outputs the division value "G(273+T1) / 289" obtained by the division to the square root calculator 177. The square root calculator 177 receives the division value "G(273+T1) / 289" output by the divider 176, and calculates the square root of the received division value "G(273+T1) / 289". The square root calculator 177 outputs the calculated square root "(G(273+T1) / 2)½" to the multiplier 178.

[0068] Multiplier 178 takes in the multiplication value "0.258×Q / P1" for each fuel supply system output by multiplier 172 and the square root "(G(273+T1) / 289)½" output by square root calculator 177. Multiplier 178 multiplies each of the multiplication values ​​for each fuel supply system by the square root to calculate Cg for each fuel supply system. Multiplier 178 outputs the calculated Cg for each fuel supply system to function calculator 179.

[0069] Function calculator 179 calculates a function (hereinafter referred to as Cg-valve opening conversion function (FX2)) that calculates the valve opening for passing the volume from Cg, which indicates the volume passing through the valve. Function calculator 179 takes in Cg for each fuel supply system output by multiplier 178, and substitutes each of the taken Cg for each fuel supply system into Cg-valve opening conversion function (FX2). Function calculator 179 outputs a signal including the valve opening calculated by substituting Cg corresponding to top hat fuel supply system 5-T, to flow rate control valve 52T. Function calculator 179 outputs a signal including the valve opening calculated by substituting Cg corresponding to pilot fuel supply system 5-P, to flow rate control valve 52P. Function calculator 179 outputs a signal including the valve opening calculated by substituting Cg corresponding to main fuel supply system 5-M, to flow rate control valve 52M, and ends the processing.

[0070] 4 has been described as being performed each time a hydrogen mass mixing ratio is recorded in the memory unit 62. However, the processes of S1-2 and S1-3 may be started each time the process of S1-1 is performed, regardless of whether a hydrogen mass mixing ratio is recorded in the memory unit 62. For example, when the multiplier 131 of the mass flow rate calculation unit 63 receives a CSO signal, it may output an instruction signal indicating the start of processing to the multiplier 141 and subtractor 142 of the mixed gas calorie ratio calculation unit 64 and the divider 161 and subtractor 162 of the volumetric flow rate calculation unit 66, thereby starting the processes of S1-2 and S1-3.

[0071] Alternatively, the processing shown in FIG. 4 may be performed without the storage unit 62 using the following hardware configuration. That is, the computing units denoted by reference numerals 131 and 132, 141 to 145, 151, 161 to 167, and 171 to 179 are configured as hardware. A number of signal generators are provided that output the values ​​of the hydrogen gas LHV, natural gas LHV, hydrogen mass mixing ratio, hydrogen gas density, natural gas density, air density, and computation constants SG1 to SG5 stored in the storage unit 62 at predetermined control cycles. Each signal generator may output its output value at each control cycle to the computing unit that reads the value from the storage unit 62 in the above-described manner. Note that the interval between these control cycles may be, for example, approximately the same as the frequency at which the CSO signal output device 14 outputs the CSO signal.

[0072] When using a method of starting the processes of S1-2 and S1-3 each time the process of S1-1 described above is performed, or when using a hardware configuration, the divider 151 of the mixed gas mass flow rate calculation unit 65, the divider 166 of the volumetric flow rate calculation unit 66, and the multiplier 175 of the valve opening calculation unit 67 do not need to perform the process of recording the mixed gas calorie ratio, mixed gas density, and mixed gas specific gravity derived from the hydrogen mass mixing ratio in an internal storage area. Each of the divider 151, the divider 166, and the multiplier 175 can take in a value from one end and a value from the other end at approximately the same timing, so it is sufficient to perform calculations using the two taken-in values ​​as the target.

[0073] (Effects of the Embodiment) When using a mixed gas in which hydrogen gas is mixed with natural gas, a measure can be taken in which the fuel flow rate command value indicated by the CSO signal is changed to a value that can guide the flow rate of the mixed gas while the proportion of hydrogen gas is small. In this case, since there is no need to significantly change the fuel flow rate command value, the relationship between the change in the fuel flow rate command value and the change in MW can be maintained substantially similar to that when hydrogen gas is not mixed. In contrast, when the proportion of hydrogen gas increases, the calories per unit volume of the mixed gas decreases compared to when the proportion of hydrogen gas is small. Therefore, in order to maintain the MW, it is necessary to increase the valve opening and supply more mixed gas, which requires a significant change in the fuel flow rate command value.

[0074] In this case, as described above, the relationship between the change in the fuel flow rate command value and the change in MW becomes significantly different from the relationship when hydrogen gas is not mixed in, and a problem arises in that some kind of change must be made to various controls such as runback and rated load operation, which are performed on the assumption that this relationship is constant.

[0075] This problem includes, for example, the following problem. The value that can be used as the fuel flow rate command value has an upper limit due to constraints, etc., of the program executed in the CSO signal output device 14 that generates the CSO signal. For example, assume that the upper limit of the fuel flow rate command value is "100." In this case, assume that the fuel flow rate command value, which was "70" under normal operating conditions without hydrogen gas mixing, is increased to "90" due to the mixing of hydrogen gas. When this increase is viewed in relation to the upper limit of "100," the range in which the fuel flow rate command value can be increased is reduced from "30" to "10." Therefore, even if the fuel flow rate command value needs to be increased by "30" to achieve 100% output of the gas turbine 2, for example, it is not possible to set a fuel flow rate command value exceeding "100," making it impossible to achieve 100% output of the gas turbine 2. To resolve this, the upper limit of the fuel flow rate command value must be changed, but this change is not a minor change and requires significant cost.

[0076] In contrast, in the above embodiment, the fuel flow rate command value indicated by the CSO signal is the same as that used when hydrogen gas is not mixed in. To use the same fuel flow rate command value as that used when hydrogen gas is not mixed in, the mixed gas mass flow rate calculation unit 65 performs a correction using the mixed gas calorie ratio calculated by the mixed gas calorie ratio calculation unit 64, i.e., calculates the mass flow rate of the mixed gas that provides the same calories as the calories provided by the mass flow rate of natural gas derived from the fuel flow rate command value. In addition to this correction, the volumetric flow rate calculation unit 66 performs a correction using the mixed gas density, and the valve opening calculation unit 67 performs a correction using the mixed gas specific gravity G. Performing these corrections in the fuel control device 6 makes it possible to supply an appropriate flow rate of mixed gas to the gas turbine 2 without changing the fuel flow rate command value. This eliminates the need to change the fuel flow rate command value, thereby preventing the above-mentioned problems.

[0077] (Supplementary configuration examples of the embodiments) The embodiments of the present disclosure have been described above in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and also includes designs within the scope that do not deviate from the gist of the present disclosure.

[0078] In the above embodiment, the hydrogen mass mixing ratio is stored in the memory unit 62, and this hydrogen mass mixing ratio is used as the target value for the hydrogen gas flow rate control valve 43. However, instead of storing the hydrogen mass mixing ratio in the memory unit 62, the target value for the hydrogen mass mixing ratio may be continuously supplied from outside to the mixed gas calorie ratio calculation unit 64, the volumetric flow rate calculation unit 66, and the hydrogen gas valve opening calculation unit 61.

[0079] When the target value of the hydrogen mass mixing ratio is continuously supplied from an external source to the hydrogen gas valve aperture calculation unit 61, the hydrogen mass mixing ratio based on actual measurement may be supplied to the mixed gas calorific ratio calculation unit 64 and the volumetric flow rate calculation unit 66 instead of the target value of the hydrogen mass mixing ratio. In this case, for example, the hydrogen gas valve aperture calculation unit 61 calculates the hydrogen mass mixing ratio based on actual measurement using the volumetric flow rate, pressure value, and temperature value of natural gas and the volumetric flow rate, pressure value, and temperature value of hydrogen gas contained in the measurement data obtained from the natural gas measurement unit 33 and the hydrogen gas measurement unit 42. The hydrogen gas valve aperture calculation unit 61 outputs the calculated hydrogen mass mixing ratio based on actual measurement to the multiplier 141 and subtractor 142 of the mixed gas calorific ratio calculation unit 64 and the divider 161 and subtractor 162 of the volumetric flow rate calculation unit 66.

[0080] Furthermore, instead of storing the hydrogen mass mixture ratio in the memory unit 62, the hydrogen volume mixture ratio in the reference state may be stored in the memory unit 62, or the hydrogen volume mixture ratio in the reference state may be continuously supplied from the outside as a target value.

[0081] In this case, the mixed gas calorific ratio calculation unit 64 will have a calculation configuration that calculates the mixed gas calorific ratio from the hydrogen volumetric mixing ratio in the reference state, and the volumetric flow rate calculation unit 66 will have a calculation configuration that calculates the mixed gas density from the hydrogen volumetric mixing ratio in the reference state. The hydrogen gas valve opening calculation unit 61 may convert the hydrogen volumetric mixing ratio in the reference state to a hydrogen mass mixing ratio and then calculate the valve opening using the procedure described above, or it may calculate the valve opening as follows. For example, the hydrogen gas valve opening calculation unit 61 may convert the hydrogen volumetric mixing ratio in the reference state to a hydrogen volumetric mixing ratio in the actual environment to set it as a target value, and calculate the valve opening of the hydrogen gas flow rate control valve 43 based on the difference between this target value and the hydrogen volumetric mixing ratio obtained by actual measurement.

[0082] When the target value of the hydrogen volume mixing ratio under the reference condition is continuously supplied from an external source to the hydrogen gas valve aperture calculation unit 61, the hydrogen volume mixing ratio under the reference condition based on actual measurement may be supplied to the mixed gas calorie ratio calculation unit 64 and the volumetric flow rate calculation unit 66 instead of the target value of the hydrogen volume mixing ratio under the reference condition. In this case, for example, the hydrogen gas valve aperture calculation unit 61 calculates the hydrogen volume mixing ratio under the reference condition based on actual measurement using the volumetric flow rate, pressure value, and temperature value of natural gas and the volumetric flow rate, pressure value, and temperature value of hydrogen gas contained in the measurement data obtained from the natural gas measurement unit 33 and the hydrogen gas measurement unit 42. The hydrogen gas valve aperture calculation unit 61 outputs the calculated hydrogen volume mixing ratio under the reference condition based on actual measurement to the mixed gas calorie ratio calculation unit 64 and the volumetric flow rate calculation unit 66.

[0083] In the above embodiment, the mixed gas fuel supply line 5 is shown to include three fuel supply systems to the gas turbine 2: a top hat fuel supply system 5-T, a pilot fuel supply system 5-P, and a main fuel supply system 5-M. However, there may be a plurality of top hat fuel supply systems 5-T, a plurality of pilot fuel supply systems 5-P, or a plurality of main fuel supply systems 5-M. In this case, the fuel distribution ratio indicates the ratio of fuel distribution to each of the plurality of top hat fuel supply systems 5-T, each of the plurality of pilot fuel supply systems 5-P, and each of the plurality of main fuel supply systems 5-M.

[0084] In the above embodiment, the value of the mixed gas calorific ratio is the value obtained by dividing the calories of a unit mass of mixed gas by the calories of a unit mass of natural gas. Conversely, the value of the mixed gas calorific ratio may be the value obtained by dividing the calories of a unit mass of natural gas by the calories of a unit mass of mixed gas. In this case, the divider 145 of the mixed gas calorific ratio calculation unit 64 divides the natural gas LHV read from the memory unit 62 by the sum output by the adder 144. The mixed gas mass flow rate calculation unit 65 includes a multiplier instead of the divider 151, and the multiplier multiplies each of the mass flow rates of natural gas for each fuel supply system output by the function calculator 132 by the value of the mixed gas calorific ratio output by the divider 145.

[0085] In the above embodiment, a mixed gas obtained by mixing natural gas with hydrogen gas is supplied to the gas turbine 2. Here, the combination of natural gas and hydrogen gas is just an example, and other combinations of fuel gases may be used. When this combination is represented as a first fuel gas and a second fuel gas, the difference between the first fuel gas and the second fuel gas may be, like the difference between natural gas and hydrogen gas, that the second fuel gas is a gas with a higher combustion rate than the first fuel gas and that the second fuel gas is a gas with a lower calorie per unit volume but a higher calorie per unit mass than the first fuel gas, or the second fuel gas may have other differences.

[0086] In the above embodiment, the CSO signal output device 14 is configured to output a CSO signal representing a fuel flow rate command value for setting the amount of power generated by the generator 25 to a target power value. In contrast to this, the CSO signal output device 14 may select any one of various control objects in the gas turbine 2 and output a CSO signal representing a fuel flow rate command value for setting the operating state of the gas turbine 2 to a desired operating state, such as outputting a CSO signal representing a fuel flow rate command value for setting the rotational speed of the rotor 24 of the gas turbine 2 to a target rotational speed value. Alternatively, the CSO signal output device 14 may calculate a plurality of fuel flow rate command values ​​corresponding to each of such various control objects, select one of the calculated plurality of fuel flow rate command values, for example, the minimum fuel flow rate command value, and output a CSO signal representing the selected fuel flow rate command value.

[0087] In the above embodiment, an example of the configuration of the valve opening calculation unit 67 has been described with reference to FIG. 6 . Incidentally, Equation (1) calculated by the valve opening calculation unit 67 is derived in accordance with the specifications of the flow rate control valves 52T, 52P, and 52M. When flow rate control valves 52T, 52P, and 52M with other specifications are used, a different equation from Equation (1) is derived. Therefore, the configuration of the valve opening calculation unit 67 is changed in accordance with the specifications of the flow rate control valves 52T, 52P, and 52M used in the gas turbine power plant 1. However, regardless of the valve opening calculation unit 67, the input and output are the same. The valve opening of each of the flow rate control valves 52T, 52P, and 52M, which corresponds to the output, is calculated based on the mixed gas density, the temperature and pressure of the mixed gas in the actual environment, and the volumetric flow rate of the mixed gas for each fuel supply system, which correspond to the input. Note that, because the air density is a constant, it may be stored in the storage unit 62 as in the above embodiment, or other configurations may be applied.

[0088] (Computer Configuration) FIG. 7 is a schematic block diagram showing the configuration of a computer according to at least one embodiment. The computer 200 includes a processor 201, a main memory 202, a storage 203, and an interface 204. The fuel control device 6 described above is implemented in the computer 200. The operations of the above-described processing units, i.e., the hydrogen gas valve opening calculation unit 61, the mass flow calculation unit 63, the mixed gas calorie ratio calculation unit 64, the mixed gas mass flow calculation unit 65, the volumetric flow calculation unit 66, and the valve opening calculation unit 67, are stored in the storage 203 in the form of a program. The processor 201 reads the program from the storage 203, loads it into the main memory 202, and executes the above-described processing in accordance with the program. The processor 201 also allocates a storage area corresponding to the above-described storage unit 62 in the main memory 202 or the storage 203 in accordance with the program. In accordance with the program, the processor 201 connects the hydrogen gas valve opening calculation unit 61 to the natural gas measurement unit 33, the hydrogen gas measurement unit 42, and the hydrogen gas flow rate control valve 43 via the interface 204, connects the mass flow rate calculation unit 63 to the CSO signal output device 14 via the interface 204, and connects the valve opening calculation unit 67 to the thermometer 12, the pressure gauge 13, and the flow rate control valves 52T, 52P, and 52M via the interface 204.

[0089] The program may be for realizing some of the functions to be performed by the computer 200. For example, the program may be a program that performs functions in combination with other programs already stored in the storage 203 or in combination with other programs implemented in other devices. In other embodiments, the computer may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor may be realized by the integrated circuit.

[0090] Examples of storage 203 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read-only memory (CD-ROM), a digital versatile disc read-only memory (DVD-ROM), and a semiconductor memory. Storage 203 may be an internal medium directly connected to the bus of computer 200, or an external medium connected to computer 200 via interface 204 or a communication line. Furthermore, if this program is distributed to computer 200 via a communication line, computer 200 that receives the program may load the program into main memory 202 and execute the above-described processing. In at least one embodiment, storage 203 is a non-transitory tangible storage medium.

[0091] <Additional Notes> The fuel control device 6 according to the embodiment of the present disclosure can be understood, for example, as follows.

[0092] (1) A fuel control device 6 according to a first aspect includes a mass flow rate calculation unit 63 that calculates a mass flow rate of the first fuel gas for each fuel supply system based on a fuel flow rate command value that brings the gas turbine 2 into a desired operating state when a first fuel gas is supplied through the fuel supply system (e.g., a top hat fuel supply system 5-T, a pilot fuel supply system 5-P, or a main fuel supply system 5-M) and a fuel distribution ratio for each fuel supply system; and a mixed gas calorie calculation unit 64 that calculates a mixed gas calorie ratio that is a ratio between a calorie of a mixed gas obtained by mixing the first fuel gas and a second fuel gas and a calorie of the first fuel gas. a mixed gas mass flow rate calculation unit 65 that calculates the mass flow rate of the mixed gas when the mixed gas is supplied through the fuel supply system instead of the first fuel gas, based on each of the mass flow rates of the first fuel gas for each of the fuel supply systems and the mixed gas calorie ratio, a volumetric flow rate calculation unit 66 that calculates a volumetric flow rate for each of the fuel supply systems based on each of the mass flow rates of the mixed gas for each of the fuel supply systems and the density of the mixed gas, and a valve opening calculation unit 67 that calculates a valve opening of a flow rate control valve for each of the fuel supply systems from each of the volumetric flow rates for each of the fuel supply systems. According to this aspect and each of the following aspects, it is possible to supply mixed gas at an appropriate flow rate to a gas turbine without changing a fuel flow rate command value.

[0093] (2) A fuel control device 6 according to a second aspect is the fuel control device of (1), in which the mixed gas calorific ratio calculation unit calculates the mixed gas calorific ratio based on the LHV of the first fuel gas, the LHV of the second fuel gas, and the mixing ratio of the first fuel gas and the second fuel gas in the mixed gas. According to this aspect, by using the mixed gas calorific ratio obtained by this aspect, it is possible to calculate with high accuracy in accordance with the accuracy of the mixing ratio the mass flow rate of the mixed gas that provides the same calories as those obtained from the mass flow rate of natural gas.

[0094] (3) A fuel control device 6 according to a third aspect is the fuel control device of (1) or (2), in which the volumetric flow rate calculation unit calculates the density of the mixed gas based on a predetermined density of the first fuel gas, a predetermined density of the second fuel gas, and a mixing ratio of the first fuel gas and the second fuel gas in the mixed gas. According to this aspect, by using the density of the mixed gas obtained by this aspect, it is possible to calculate the volumetric flow rate of the mixed gas with high accuracy based on the accuracy of the mixing ratio from the mass flow rate of the mixed gas.

[0095] (4) A fuel control device 6 according to a fourth aspect is the fuel control device of (2) or (3), in which the mixture ratio is a mixture ratio in mass or a mixture ratio in volume.

[0096] (5) A fuel control device 6 according to a fifth aspect is the fuel control device of (2) or (3), in which the mixture ratio is a mixture ratio that is determined appropriately or a mixture ratio that is obtained by actual measurement.

[0097] (6) A fuel control device 6 according to a sixth aspect is the fuel control device of any one of (1) to (5), in which the valve opening calculation unit calculates the valve opening of the flow rate control valve for each of the fuel supply systems based on the density of the mixed gas, a predetermined density of air, the temperature and pressure of the mixed gas in an actual environment, and the volumetric flow rate for each of the fuel supply systems. According to this aspect, by using the specific gravity of the mixed gas obtained from the density of the mixed gas and the density of the air, it is possible to calculate the valve opening with high accuracy based on the accuracy of the mixture ratio from the volumetric flow rate of the mixed gas.

[0098] (7) A fuel control device 6 according to a seventh aspect is any one of the fuel control devices (1) to (6), in which the second fuel gas (e.g., hydrogen gas) has a lower calorie per unit volume than the first fuel gas (e.g., natural gas), a higher calorie per unit mass than the first fuel gas, and a faster combustion rate than the first fuel gas.

[0099] According to the fuel control device, fuel control method, and program of the present disclosure, it is possible to supply a mixed gas at an appropriate flow rate to a gas turbine without changing the fuel flow rate command value.

[0100] DESCRIPTION OF SYMBOLS 1...Gas turbine power plant 2...Gas turbine 3...Natural gas fuel supply line 4...Hydrogen gas fuel supply line 5...Mixed gas fuel supply line 5-T...Top hat fuel supply system 5-P...Pilot fuel supply system 5-M...Main fuel supply system 6...Fuel control device 10...Fuel supply line connection section 11...Wattmeter 12...Thermometer 13...Pressure gauge 14...CSO signal output device 21...Air compressor 22...Combustor 23...Turbine 24...Rotor 25...Generator 31...Natural gas supply source 32...Compressor 33...Natural gas measurement section 41...Hydrogen gas supply source 42...Hydrogen gas measurement section 43...Hydrogen gas flow rate control valve 51...Inlet piping 52T, 52P, 52M...Flow rate control valve 53T, 53P, 53M...Outlet piping 61...Hydrogen gas valve opening calculation section 62...Memory section 63...Mass flow rate calculation section 64... Mixed gas calorie ratio calculation section 65... Mixed gas mass flow rate calculation section 66... ​​Volumetric flow rate calculation section 67... Valve opening degree calculation section

Claims

1. A fuel control device comprising: a mass flow rate calculation unit that calculates a mass flow rate of the first fuel gas for each fuel supply system based on a fuel flow rate command value that puts a gas turbine into a desired operating state when a first fuel gas is supplied through the fuel supply system and a fuel allocation ratio for each of the fuel supply systems; a mixed gas calorie ratio calculation unit that calculates a mixed gas calorie ratio, which is a ratio of a calorie of a mixed gas obtained by mixing the first fuel gas and a second fuel gas to a calorie of the first fuel gas; a mixed gas mass flow rate calculation unit that calculates a mass flow rate of the mixed gas when the mixed gas is supplied through the fuel supply system in place of the first fuel gas, based on each of the mass flow rates of the first fuel gas for each of the fuel supply systems and the mixed gas calorie ratio; a volumetric flow rate calculation unit that calculates a volumetric flow rate for each of the fuel supply systems based on each of the mass flow rates of the mixed gas for each of the fuel supply systems and a density of the mixed gas; and a valve opening calculation unit that calculates a valve opening of a flow rate control valve for each of the fuel supply systems from each of the volumetric flow rates for each of the fuel supply systems.

2. A fuel control device according to claim 1, wherein the mixed gas calorie ratio calculation unit calculates the mixed gas calorie ratio based on the LHV of the first fuel gas, the LHV of the second fuel gas, and the mixing ratio of the first fuel gas to the second fuel gas in the mixed gas.

3. The fuel control device according to claim 1, wherein the volumetric flow rate calculation unit calculates the density of the mixed gas based on a predetermined density of the first fuel gas, a predetermined density of the second fuel gas, and a mixing ratio of the first fuel gas and the second fuel gas in the mixed gas.

4. A fuel control device according to claim 2 or 3, wherein the mixture ratio is a mixture ratio in mass or a mixture ratio in volume.

5. A fuel control device according to claim 2 or 3, wherein the mixture ratio is a mixture ratio that is determined appropriately or a mixture ratio that is obtained by actual measurement.

6. A fuel control device according to claim 1, wherein the valve opening calculation unit calculates the valve opening of the flow rate control valve for each of the fuel supply systems based on the density of the mixed gas, a predetermined density of air, the temperature and pressure of the mixed gas in an actual environment, and the volumetric flow rate for each of the fuel supply systems.

7. A fuel control device according to claim 1, wherein the second fuel gas has a lower calorie per unit volume than the first fuel gas, a higher calorie per unit mass than the first fuel gas, and a faster combustion rate than the first fuel gas.

8. A fuel control method comprising: calculating a mass flow rate of the first fuel gas for each fuel supply system based on a fuel flow rate command value that puts a gas turbine in a desired operating state when a first fuel gas is supplied through the fuel supply system and a fuel allocation ratio for each of the fuel supply systems; calculating a mixed gas calorie ratio that is a ratio of the calories of the first fuel gas to the calories of a mixed gas obtained by mixing the first fuel gas and a second fuel gas; calculating a mass flow rate of the mixed gas when the mixed gas is supplied through the fuel supply system in place of the first fuel gas based on each of the mass flow rates of the first fuel gas for each of the fuel supply systems and the mixed gas calorie ratio; calculating a volumetric flow rate for each of the fuel supply systems based on each of the mass flow rates of the mixed gas for each of the fuel supply systems and the density of the mixed gas; and calculating a valve opening of a flow rate control valve for each of the fuel supply systems from each of the volumetric flow rates for each of the fuel supply systems.

9. A program causing a computer to function as: a mass flow rate calculation means for calculating a mass flow rate of the first fuel gas for each fuel supply system, based on a fuel flow rate command value that puts the gas turbine into a desired operating state when the first fuel gas is supplied through the fuel supply system and a fuel distribution ratio for each of the fuel supply systems; a mixed gas calorie ratio calculation means for calculating a mixed gas calorie ratio, which is the ratio of the calorie of the first fuel gas to the calorie of a mixed gas obtained by mixing the first fuel gas and the second fuel gas; a mixed gas mass flow rate calculation means for calculating the mass flow rate of the mixed gas when the mixed gas is supplied through the fuel supply system in place of the first fuel gas, based on each of the mass flow rates of the first fuel gas for each of the fuel supply systems and the mixed gas calorie ratio; a volumetric flow rate calculation means for calculating a volumetric flow rate for each of the fuel supply systems, based on each of the mass flow rates of the mixed gas for each of the fuel supply systems and the density of the mixed gas; and a valve opening calculation means for calculating a valve opening of a flow rate control valve for each of the fuel supply systems from each of the volumetric flow rates for each of the fuel supply systems.

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