JP7119690B2 - Fuel cell system, method for measuring flow rate of raw fuel gas, and method for specifying gas type of raw fuel gas - Google Patents

Description

The present disclosure relates to a fuel cell system including a fuel cell that generates power through an electrochemical reaction between an anode gas and a cathode gas, a method for measuring the flow rate of the raw fuel gas of the anode gas, and a method for specifying the gas type.

Conventionally, a hydrogen generator that generates a hydrogen-containing gas (anode gas) from a hydrogen-containing fuel (raw fuel gas), a cell stack that generates power using the hydrogen-containing gas, and a fuel supplied to the hydrogen generator. A fuel flow meter that acquires the supply amount, a sensor that detects oxygen or nitrogen in the fuel on the upstream side of the hydrogen generator, and based on the detection result of the sensor, corrects the error contained in the value from the fuel flow meter. A fuel cell system is known that includes a correction unit that acquires the supply amount of fuel containing air by performing the above-described operation (see, for example, Patent Document 1). In this fuel cell system, even if the hydrogen-containing fuel is supplied to the hydrogen generator while being mixed with air, it is possible to appropriately adjust the supply amount of the hydrogen-containing fuel according to the amount of air mixed. can. Conventionally, as a fuel processing system for a fuel cell that converts raw fuel (raw fuel gas) containing hydrocarbons, alcohols or ethers and raw water or steam into hydrogen-rich fuel gas (anode gas), It is known to include dew point temperature measuring means, calculation means for estimating the raw fuel flow rate based on the dew point temperature, and flow rate adjustment means for adjusting the raw fuel flow rate based on the calculation result (see, for example, Patent Document 2). . According to this fuel processing system, even if the flow rate of raw fuel or raw water (steam) deviates from the set value for some unintended reason, stable operation of the fuel cell and protection of the system can be achieved.

JP 2012-169214 A Japanese Patent No. 4038390

As the raw fuel gas for the anode gas of the fuel cell as described above, town gas or propane gas containing combustible components such as methane, ethane, propane and butane is generally used. concentration ratio) varies depending on the gas supplier and region (gas origin), etc. Depending on the region, the composition (gas type) of the raw fuel gas may change over time. If the composition (gas type) of the raw fuel gas supplied to the fuel cell system changes, the error in the detection value of the fuel flow meter increases according to the composition change, and the raw fuel gas (calorific value) is insufficient. This may lead to a decrease in the output of the fuel cell system due to oversupply of the raw fuel gas, and a decrease in durability due to a temperature rise due to oversupply of the raw fuel gas. However, the techniques described in Patent Literatures 1 and 2 do not take into account any changes in the composition of the raw fuel gas.

Therefore, the main object of the present disclosure is to suppress a decrease in the output and durability of the fuel cell system even when the composition of the raw fuel gas changes.

A fuel cell system of the present disclosure includes a fuel cell that generates power through an electrochemical reaction between an anode gas and a cathode gas, and a reformer that reforms raw fuel gas to generate the anode gas, A plurality of flowmeters each detecting the flow rate of the raw fuel gas supplied to the reformer, wherein the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas. and a plurality of flowmeters having different characteristics of change in the amount of deviation with respect to the composition, and at least one of the flowmeters based on the characteristics and the detected values of the plurality of flowmeters and calculating the flow rate of the raw fuel gas supplied to the reformer from the calculated deviation amount and the detection value of at least one of the flowmeters and

The fuel cell system of the present disclosure includes a plurality of flowmeters for detecting the flow rate of the raw fuel gas supplied to the reformer, and the raw fuel supplied to the reformer based on the detected values of the plurality of flowmeters. and an arithmetic processing unit that calculates the gas flow rate. Each flowmeter is configured so that the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas. The characteristics of changes in the amount of deviation are different from each other. That is, the plurality of flowmeters basically output different values as the flow rate of the raw fuel gas of a certain composition, and the difference between the detection values of the plurality of flowmeters is determined according to the characteristics of each flowmeter. corresponds to the difference between the amounts of deviation of the detected values with respect to the true values of . Therefore, it is possible to calculate the amount of deviation of the detected value from the true value of at least one of the flow meters based on the characteristics and detected values of the plurality of flow meters, and the calculated amount of deviation and the at least one The flow rate of the raw fuel gas to be supplied to the reformer can be accurately calculated from the detected value of the flow meter. As a result, in the fuel cell system of the present disclosure, even when the composition of the raw fuel gas changes, the flow rate of the raw fuel gas supplied to the reformer can be accurately obtained by the arithmetic processing unit. Therefore, the required anode gas can be accurately supplied from the reformer to the fuel cell. As a result, even if the composition of the raw fuel gas changes, it is possible to satisfactorily suppress the deterioration of the output and durability of the fuel cell system due to the excess or deficiency of the raw fuel gas. The fuel cell system may include two flowmeters, or may include three or more flowmeters. By using three or more flowmeters, the arithmetic processing unit The accuracy of the calculated raw fuel gas flow rate can be further improved.

Further, for each of the plurality of flowmeters, the difference between the specific heat difference between the standard gas, which is the raw fuel gas whose composition is known, and the raw fuel gas supplied to the reformer, and the amount of deviation A function indicating the relationship may be specified, and the arithmetic processing unit calculates the specific heat difference based on the function and the detected value of the plurality of flowmeters, and calculates the calculated specific heat difference and the at least one The deviation amount may be calculated from the function of one flow meter. That is, the specific heat of the raw fuel gas has a correlation with the composition (concentration of combustible components) of the raw fuel gas, and the difference in specific heat between the standard gas and the raw fuel gas supplied to the reformer is and the standard gas. Therefore, it is possible to define a function indicating the relationship between the specific heat difference and the deviation amount for each of the plurality of flow meters, and by calculating the specific heat difference based on the function and the detected value of the plurality of flow meters, From the specific heat difference and the function of at least one of the flowmeters, it is possible to accurately calculate the amount of deviation of the detected value from the true value of the flowmeter.

Furthermore, the arithmetic processing unit may calculate the specific heat difference from the difference between the detection values of the plurality of flowmeters and the difference between the deviation amounts obtained from the function. This makes it possible to accurately calculate the specific heat difference between the standard gas and the raw fuel gas supplied to the reformer.

Further, the arithmetic processing unit may specify the gas type of the raw fuel gas to be supplied to the reformer based on the specific heat difference and the specific heat of the standard gas. That is, the specific heat of the raw fuel gas has a correlation with the composition (concentration of combustible components) of the raw fuel gas, and can be obtained from the specific heat difference and the specific heat of the standard gas. Therefore, by calculating the specific heat difference, it is possible to accurately identify the gas type of the raw fuel gas from the specific heat difference and the specific heat of the standard gas. By reflecting the identified gas type of the raw fuel gas in the control of the fuel cell system, it is possible to maintain good performance and durability of the fuel cell.

Further, the fuel processing system may include a raw fuel gas pump that supplies the raw fuel gas to the reformer, and a pump control unit that controls the raw fuel gas pump, wherein the pump control unit setting a target flow rate of the raw fuel gas based on the target current value of the fuel cell and the amount of heat corresponding to the gas type of the raw fuel gas; The raw fuel gas pump may be controlled so as to match the target flow rate. As a result, the flow rate of the raw fuel gas can be calculated with high accuracy, and the target flow rate of the raw fuel gas can be set more appropriately according to the gas type (composition) of the raw fuel gas being supplied to the reformer. Therefore, it is possible to more accurately supply the required anode gas from the reformer to the fuel cell.

A raw fuel gas flow rate measuring method of the present disclosure is a raw fuel gas flow rate measuring method for measuring the flow rate of raw fuel gas supplied to a reformer that generates anode gas of a fuel cell, A plurality of flowmeters configured so that the amount of deviation of the detected value from the true value varies according to the composition of the raw fuel gas, and having different characteristics of the variation of the amount of deviation with respect to the composition, the reforming detecting the flow rate of the raw fuel gas supplied to the vessel, calculating the deviation amount of at least one of the flow meters based on the characteristics and the detected values of the plurality of flow meters, and calculating the calculated deviation A flow rate of the raw fuel gas supplied to the reformer is calculated from the amount and the detection value of at least one of the flowmeters.

According to this method, even if the composition of the raw fuel gas changes, it is possible to obtain the flow rate of the raw fuel gas supplied to the reformer with high accuracy. can accurately supply the anode gas according to the demand. As a result, even if the composition of the raw fuel gas changes, it is possible to satisfactorily suppress the deterioration of the output and durability of the fuel cell system due to the excess or deficiency of the raw fuel gas.

Another fuel cell system of the present disclosure includes a fuel cell that generates power through an electrochemical reaction between an anode gas and a cathode gas, and a reformer that reforms raw fuel gas to generate the anode gas. a plurality of flowmeters for detecting the flow rate of the raw fuel gas supplied to the reformer, wherein the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas a plurality of flowmeters configured to vary and having different characteristics of the change in the amount of deviation with respect to the composition; and a function defined for each of the plurality of flowmeters, wherein the composition is known. A function indicating the relationship between the specific heat difference between the standard gas, which is the raw fuel gas, and the raw fuel gas supplied to the reformer, and the amount of deviation, and the detection values of the plurality of flow meters a gas type specifying unit for calculating the specific heat difference based on the standard gas and specifying the gas type of the raw fuel gas to be supplied to the reformer based on the calculated specific heat difference and the specific heat of the standard gas; It is a thing.

Such a fuel cell system includes a plurality of flowmeters for detecting the flow rate of the raw fuel gas supplied to each reformer, and a gas type identification unit for identifying the gas type of the raw fuel gas supplied to the reformer. include. Each flowmeter is configured so that the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas. The characteristics of changes in the amount of deviation are different from each other. Furthermore, for each flow meter, the difference in specific heat between the standard gas, which is the raw fuel gas whose composition is known, and the raw fuel gas supplied to the reformer, and the detected value for the true value of the flow rate in the flow meter A function indicating the relationship with the amount of deviation is specified. Here, the specific heat of the raw fuel gas has a correlation with the composition (concentration of combustible components) of the raw fuel gas, and the difference in specific heat between the standard gas and the raw fuel gas supplied to the reformer is the raw fuel It changes according to the difference in composition between the gas and the standard gas. Therefore, it is possible to calculate the specific heat difference based on the functions and detected values of a plurality of flowmeters, and the ratio of the raw fuel gas supplied to the reformer based on the calculated specific heat difference and the specific heat of the standard gas. Gas species can be specified with high accuracy. By reflecting the specified gas type of the raw fuel gas in the control of the fuel cell system, even if the composition of the raw fuel gas changes, the output of the fuel cell system will decrease due to the excess or deficiency of the raw fuel gas. It is possible to satisfactorily suppress deterioration of durability and durability.

A raw fuel gas type identification method of the present disclosure is a raw fuel gas type identification method for identifying the gas type of raw fuel gas supplied to a reformer that generates anode gas of a fuel cell, A plurality of flowmeters configured so that the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas, and the characteristics of the variation of the amount of deviation with respect to the composition are different from each other. The flow rate of the raw fuel gas supplied to the reformer is detected, and the standard gas, which is the raw fuel gas whose composition is known, and the reformed gas are functions defined for each of the plurality of flow meters. The specific heat difference is calculated based on the function indicating the relationship between the specific heat difference with the raw fuel gas supplied to the masser and the amount of deviation, and the detection values of the plurality of flow meters, and the calculated The gas type of the raw fuel gas supplied to the reformer is specified based on the specific heat difference and the specific heat of the standard gas.

According to this method, even if the composition of the raw fuel gas changes, it is possible to satisfactorily suppress the decrease in the output and durability of the fuel cell system due to the excess or deficiency of the raw fuel gas.

1 is a schematic configuration diagram showing a fuel cell system of the present disclosure; FIG. 2 is a chart showing characteristics of a plurality of flowmeters included in the fuel cell system of FIG. 1; 4 is a flow chart showing an example of a routine executed in the fuel cell system of the present disclosure; FIG. 4 is a schematic configuration diagram showing another fuel cell system of the present disclosure; 5 is a chart showing characteristics of a plurality of flowmeters included in the fuel cell system of FIG. 4; FIG.

Next, embodiments for carrying out the invention of the present disclosure will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a fuel cell system 10 of the present disclosure. The fuel cell system 10 shown in FIG. and a controller 80 for controlling the entire system. The power generation unit 20 includes a fuel cell stack FCS, a power generation module 30 including a box-shaped module case 31 made of a heat insulating material, a vaporizer (evaporator) 33, two reformers 34, and the like. A raw fuel gas supply system 40 for supplying a raw fuel gas (raw fuel) such as city gas (natural gas) or LP gas to the vaporizer 33 of the module 30, and a cathode gas to the fuel cell stack FCS of the power generation module 30. A cathode gas supply system 50 for supplying the air of the power generation module 30, a reforming water supply system 55 for supplying reforming water to the vaporizer 33 of the power generation module 30, exhaust heat recovery system 60, a power conditioner 71 connected to the output terminal of the fuel cell stack FCS, and a housing 22 accommodating them.

In this embodiment, the power generation module 30 includes two fuel cell stacks FCS, and the two fuel cell stacks FCS are installed on a manifold 32 arranged inside the module case 31 so as to face each other with a space therebetween. be. Each fuel cell stack FCS has an electrolyte such as zirconium oxide, an anode electrode and a cathode electrode sandwiching the electrolyte, and a plurality of solid oxide type single cells arranged in the left-right direction (horizontal direction) in FIG. Contains Cell SC. An anode gas passage (not shown) is formed in the anode electrode of each unit cell SC so as to extend in a direction perpendicular to the arrangement direction of the unit cells SC, that is, in the vertical direction. Further, a cathode gas passage (not shown) through which cathode gas flows is formed around the cathode electrode of each unit cell SC so as to extend in a direction perpendicular to the arrangement direction of the unit cells SC, that is, in the vertical direction. The anode gas passage of each single cell SC is connected to the anode gas passage 320 formed in the manifold 32 , and the cathode gas passage of each single cell SC is connected to the cathode gas passage 310 inside the module case 31 .

The vaporizer 33 and the reformer 34 of the power generation module 30 are arranged above the two fuel cell stacks FCS in the module case 31 with a space therebetween. In this embodiment, the vaporizer 33 and one reformer 34 are arranged above one fuel cell stack FCS, and the other reformer 34 is arranged above the other fuel cell stack FCS. Further, between one fuel cell stack FCS and the vaporizer 33 and one reformer 34 and between the other fuel cell stack FCS and the other reformer 34 in the vertical direction, fuel cell stack FCS A combustion section 35 is defined to generate the heat necessary for the operation of the vaporizer 33 and the reaction in the reformer 34 . An ignition heater 36 is installed in each combustion section 35, and a temperature sensor 37 is installed in at least one of the combustion sections 35 so as to be close to the fuel cell stack FCS.

The vaporizer 33 heats the raw fuel gas from the raw fuel gas supply system 40 and the reforming water from the reforming water supply system 55 with the heat from the combustion unit 35, preheats the raw fuel gas, and heats the reforming water. evaporate to form water vapor. The raw fuel gas preheated by the vaporizer 33 is mixed with water vapor, and the mixed gas of the preheated raw fuel gas and water vapor flows from the vaporizer 33 into the reformer 34 . The reformer 34 has, for example, a Ru-based or Ni-based reforming catalyst filled therein, and in the presence of heat from the combustion section 35, the mixed gas from the vaporizer 33 reacts with the reforming catalyst. A (steam reforming reaction) produces hydrogen gas and carbon monoxide. Furthermore, the reformer 34 produces hydrogen gas and carbon dioxide through a reaction (carbon monoxide shift reaction) between carbon monoxide produced in the steam reforming reaction and steam. As a result, the reformer 34 generates anode gas containing hydrogen, carbon monoxide, carbon dioxide, water vapor, unreformed raw fuel gas, and the like. The anode gas generated by the reformer 34 is supplied to the anode electrode of each single cell SC via a pipe (not shown) or the anode gas passage 320 of the manifold 32 .

Also, air as a cathode gas containing oxygen is supplied to the cathode electrode of each single cell SC of the fuel cell stack FCS through the cathode gas passage 310 in the module case 31 . Oxide ions (O ₂ ⁻ ) are generated at the cathode electrode of each single cell SC, and the oxide ions permeate the electrolyte and react with hydrogen and carbon monoxide at the anode electrode to obtain electrical energy. The anode gas (hereinafter referred to as “anode off-gas”) and cathode gas (hereinafter referred to as “cathode off-gas”) that have not been used in the electrochemical reaction (power generation) in each single cell SC are discharged into the anode gas passage of each single cell SC and It flows out from the cathode gas passage to the upper combustion section 35 .

The anode off-gas that has flowed into the combustion section 35 from each single cell SC is a combustible gas that contains fuel components such as hydrogen and carbon monoxide, and is mixed with the oxygen-containing cathode off-gas that has flowed into the combustion section 35 from each single cell SC. Fit. A mixed gas of the anode off-gas and the cathode off-gas is hereinafter referred to as "off-gas". When offgas (anode offgas) is ignited by the ignition heater 36 and ignited in the combustion unit 35, the combustion of the offgas activates the fuel cell stack FCS, preheats the raw fuel gas in the vaporizer 33, and produces water vapor. Heat necessary for production, steam reforming reaction in the reformer 34, etc. is generated. In addition, combustion exhaust gas containing water vapor is generated in the combustion section 35 as the off-gas is burned.

As shown in FIG. 1, a raw fuel gas supply system 40 includes a raw fuel gas supply pipe 41 connecting a raw fuel supply source 1 that supplies city gas or LP gas and a vaporizer 33, and the raw fuel gas supply pipe 41. A raw fuel gas supply valve (electromagnetic on-off valve) 42 and a raw fuel gas pump 44 incorporated in the raw fuel gas supply pipe 41 so as to be positioned between the vaporizer 33 and the raw fuel gas pump 44, for example, normal temperature A desulfurization type desulfurizer 45 is included. Further, a pressure sensor 46 and first and second flowmeters 47 and 48 are incorporated between the raw fuel gas supply valve 42 of the raw fuel gas supply pipe 41 and the raw fuel gas pump 44 . The pressure sensor 46 is incorporated in the raw fuel gas supply pipe 41 so as to be positioned near the discharge port of the raw fuel gas pump 44 and detects the pressure of the raw fuel gas flowing through the raw fuel gas supply pipe 41 . The first and second flowmeters 47 and 48 are thermal flowmeters including temperature sensors and heaters (not shown). The flow rate per unit time of the raw fuel gas flowing through the raw fuel gas supply pipe 41 toward the reformer 34 (vaporizer 33) is detected.

The cathode gas supply system 50 includes a cathode gas supply pipe 51 connected to the cathode gas passage 310 in the module case 31, an air filter 52 installed at the gas inlet of the cathode gas supply pipe 51, and the cathode gas supply pipe 51. and an integrated blower 53 . By operating the blower 53 , air as the cathode gas sucked through the air filter 52 is pressure-fed (supplied) by the blower 53 through the cathode gas passage 310 to each fuel cell stack FCS. Further, the cathode gas supply pipe 51 is provided with a flow rate switch 54 that is turned on when the flow rate of the cathode gas flowing through the cathode gas supply pipe 51 per unit time reaches a predetermined value.

The reforming water supply system 55 includes a reforming water supply pipe 56 connected to the vaporizer 33, a reforming water tank 57 connected to the reforming water supply pipe 56 and storing reforming water, and reforming water. and a reformed water pump 58 incorporated in the supply tube 56 . By operating the reformed water pump 58 , the reformed water in the reformed water tank 57 is pumped (supplied) to the vaporizer 33 by the reformed water pump 58 . A water purifier (not shown) for purifying the stored reformed water is installed in the reformed water tank 57 .

The exhaust heat recovery system 60 is a circulation pipe 61 connected to the hot water storage tank 101 of the hot water supply unit 100, and a heat exchanger that exchanges heat between hot water flowing through the circulation pipe 61 and combustion exhaust gas from the combustion unit 35 of the power generation module 30. 62 and a circulation pump 63 incorporated in the circulation pipe 61 . By operating the circulation pump 63, the hot water stored in the hot water storage tank 101 is introduced into the heat exchanger 62 by the circulation pump 63, and the heat exchanger 62 removes heat from the combustion exhaust gas to heat the hot water. It can be returned to the hot water storage tank 101 .

Furthermore, the exhaust heat recovery system 60 includes a radiator 64 incorporated in the circulation pipe 61 , a radiator fan (electric fan) 65 that feeds air into the radiator 64 , and electric power from the power generation module 30 . It includes an electric heater (for example, a ceramic heater) 66 that heats hot water and a thermistor (temperature sensor) 67 that detects the temperature of the hot water heated by the electric heater 66 . A radiator 64 is incorporated in the circulation pipe 61 so as to be positioned between the heat exchanger 62 and the circulation pump 63 , and an electric heater 66 is installed in the circulation pipe 61 so as to be positioned between the circulation pump 63 and the radiator 64 . incorporated. Furthermore, the thermistor 67 is installed downstream of the electric heater 66 so as to be close to the electric heater 66 .

The electric heater 66 is operated to consume surplus power when the output required of the power generation module 30 (fuel cell stack FCS) is lower than the normal rated output. Further, at this time, the circulation pump 63 is duty-controlled so that the water temperature detected by the thermistor 67 becomes a predetermined temperature, and the radiator fan 65 is operated as necessary. As a result, even when the output required for the power generation module 30 is low, the heat exchanger 62 recovers the exhaust heat of each fuel cell stack FCS, and the electric heater 66 consumes the surplus power of the power generation module. Meanwhile, the operation of the power generation module 30 can be continued. In addition, by appropriately operating the radiator fan 65 to send air into the radiator 64, the hot water flowing through the circulation pipe 61 is cooled (heat is released), and the temperature of the hot water in the hot water storage tank 101 is prevented from rising more than necessary. can do.

In addition, the heat exchanger 62 (passage of combustion exhaust gas) of the exhaust heat recovery system 60 is connected to the reforming water tank 57 via a pipe, and the water vapor in the combustion exhaust gas mixes with the hot water from the hot water storage tank 101. The condensed water obtained by condensing by the exchange is introduced into the reforming water tank 57 through the pipe. Furthermore, the passage of combustion exhaust gas of the heat exchanger 62 is connected to an exhaust pipe 68 . As a result, the exhaust gas discharged from the combustion section 35 of the power generation module 30 and from which moisture has been removed by the heat exchanger 62 is discharged into the atmosphere through the exhaust pipe 68 .

The power conditioner 71 includes a DC/DC converter that boosts the DC power from each fuel cell stack FCS, an inverter that converts the DC power from the DC/DC converter into AC power, and the like (not shown). An output terminal of the power conditioner 71 (inverter) is connected to the power line 3 connected to the system power supply 2 . This makes it possible to convert the DC power from each fuel cell stack FCS into AC power and supply it to the load 4 such as a home appliance. Furthermore, the fuel cell system 10 includes a power board 72 connected to the power conditioner 71 . The power supply board 72 converts the DC power from each fuel cell stack FCS and the AC power from the system power supply 2 into low-voltage DC power, and supplies the raw fuel gas supply valve 42, the raw fuel gas pump 44, the blower 53, and the reforming water pump. 58, auxiliary equipment such as the circulation pump 63 and the radiator fan 65, sensors such as the temperature sensor 37, and the controller 80, etc., with the DC power.

In addition, a cooling fan (not shown) for cooling the power conditioner 71, the power supply board 72, etc., and a ventilation fan 24 are arranged in the auxiliary equipment room in which the power conditioner 71, the power supply board 72, etc. are arranged. It is A cooling fan (not shown) sends air to the heat-generating portions of the power conditioner 71 and the power supply substrate 72 , and the air heated by cooling the heat-generating portions is discharged into the atmosphere by the ventilation fan 24 .

The control device 80 is a computer including a CPU 81, a ROM 82 that stores various programs, a RAM 83 that temporarily stores data, an input port, an output port, and the like (all not shown). The controller 80 inputs the detected values of the temperature sensor 37, the pressure sensor 46, the first and second flow meters 47, 48, the thermistor 67, etc., the signal from the flow switch 54, and the like through the input port. The control device 80 also controls the ventilation fan 24, the ignition heater 36, the solenoid of the raw fuel gas supply valve 42, the raw fuel gas pump 44, the blower 53, the reforming water pump 58, the circulation pump 63, the radiator fan 65, and the electric heater 66. , a power conditioner 71 (DC/DC converter and inverter), a power supply substrate 72, a display unit (not shown), etc., through output ports to control these devices. Furthermore, a remote controller (not shown) is connected to the control device 80 via a wireless or wired communication line. The control device 80 executes various controls based on signals from the remote controller operated by the user of the fuel cell system 10 .

FIG. 2 is a chart showing characteristics of the first and second flowmeters 47, 48 included in the fuel cell system 10. As shown in FIG. As shown in the figure, the first and second flowmeters 47 and 48 detect that the amount of deviation d of the detected value from the true value of the flow rate is the standard gas (for example, 13A city gas) of which composition is known and the original gas. It is configured to change approximately in proportion to the specific heat difference ΔC with the raw fuel gas flowing through the fuel gas supply pipe 41 . Also, as shown in the figure, the first flow meter 47 and the second flow meter 48 have different characteristics of change in the deviation amount d with respect to the specific heat difference ΔC.

In this embodiment, the relationship between the specific heat difference ΔC in the first flow meter 47 and the amount of deviation d is represented by the first function f ₁ (ΔC) shown in the following equation (1), and the specific heat difference in the second flow meter 48 The relationship between ΔC and the amount of deviation d is represented by a second function f ₂ (ΔC) shown in the following equation (2). However, “a ₁ ” and “b ₁ ” in formula (1) and “a ₂ ” and “b ₂ ” in formula (2) are both predetermined constants, and constants a ₁ and a ₂ are , a ₁ ≠a ₂ ≠0. Also, the constants _{b 1} and _{b 2} may be zero or may be real numbers _{other than} zero. good.

d=f ₁ (ΔC)=a ₁ ΔC+b ₁ (1)
d=f2(ΔC)= _a2 ·ΔC ₊ b2 ( ₂ )

Here, the specific heat of the raw fuel gas such as city gas or LP gas has a correlation with the composition of the raw fuel gas (concentration of combustible components such as methane, ethane, propane, butane), and the standard gas and the raw fuel gas supply pipe The specific heat difference ΔC with the raw fuel gas flowing through 41 changes according to the difference in composition between the raw fuel gas and the standard gas. Therefore, the first and second flowmeters 47, 48 have the characteristic that the amount of deviation d1, d2 of the detected value from the true value of the flow rate changes according to the composition of the raw fuel gas flowing through the raw fuel gas supply pipe 41. . Then, the first and second flowmeters 47 and 48 basically (except when the specific heat difference ΔC is a value corresponding to the intersection of the first and second functions) as the flow rate of the raw fuel gas of a certain composition Different values are output, and the difference ΔF between the detection values of the _first and second flowmeters 47 and 48 is, as shown in FIG. This coincides with the difference (=d2-d1) between d1 and the deviation amount d2 of the second flow meter 48 determined from the second function f ₂ (ΔC).

Next, a procedure for measuring the flow rate of the raw fuel gas and a procedure for controlling the raw fuel gas pump 44 in the fuel cell system 10 described above will be described.

FIG. 3 shows that when the fuel cell system 10 is started (for example, when executing a fuel adsorption process for adsorbing fuel components to the desulfurizer 45 in order to suppress the air-fuel ratio deviation of the mixed gas) or during operation, the raw fuel gas 4 is a flow chart showing an example of a routine that is repeatedly executed by the control device 80 at predetermined time intervals to control the raw fuel gas pump 44 while measuring the flow rate of . At the start of the routine of FIG. 3, the CPU 81 of the control device 80 first acquires the detection value F1 of the first flow meter 47 and the detection value F2 of the second flow meter 48 (step S100), and detects the detection value F1 and A difference ΔF (=F2−F1) from the value F2 is calculated (step S110).

Next, the CPU 81 calculates the first and second functions f ₁ (ΔC) and f ₂ (ΔC) defined for the first and second flowmeters 47 and 48, the difference ΔF between the detected value F1 and the detected value F2, and , the specific heat difference ΔCx between the standard gas and the raw fuel gas flowing through the raw fuel gas supply pipe 41 toward the reformer 34 at that time is calculated (step S120). As described above, the difference ΔF between the detection values F1 and F2 of the first and second flowmeters 47 and 48 is the deviation amount d1 of the first flowmeter 47 determined from the first function f ₁ (ΔC) and the second function Since it matches the difference (=d2-d1) from the deviation amount d2 of the second flow meter 48 determined from f ₂ (ΔC), the following equation (3) holds. Therefore, in step S120, the CPU 81 calculates the specific heat difference ΔCx from the following equation (4) obtained by modifying the equation (3).

ΔF=a ₂ ΔCx+b ₂ −(a ₁ ΔCx+b ₁ ) (3)
ΔCx=(ΔF+b ₁ -b ₂ )/(a ₂ -a ₁ ) (4)

After calculating the specific heat difference ΔCx in step S120, the CPU 81 determines the deviation amount d1 of the detection value F1 of the first flowmeter 47 from the true value of the flow rate of the raw fuel gas flowing through the raw fuel gas supply pipe 41 to the above-mentioned first Based on the function f ₁ (ΔC) and the specific heat difference ΔCx, it is calculated as d1=a ₁ ΔCx+b ₁ (step S130). Further, the CPU 81 subtracts the amount of deviation d1 calculated in step S130 from the detection value F1 of the first flow meter 47 obtained in step S100 to obtain the true value of the flow rate of the raw fuel gas flowing through the raw fuel gas supply pipe 41. Ft (=F1-d1) is calculated (step S140).

In step S130 of FIG. 3, instead of the deviation amount d1 of the first flow meter 47, the deviation amount d2 of the second flow meter 48 is calculated based on the second function f ₂ (ΔC) and the specific heat difference ΔCx. It may be calculated as d2=a ₂ ·ΔCx+b ₂ , and in this case, in step S140, the true value Ft of the flow rate of the raw fuel gas may be calculated as Ft=F2−d2. Further, in step S130 of FIG. 3, both the deviation amount d1 of the first flow meter 47 and the deviation amount d2 of the second flow meter 48 may be calculated. The raw fuel gas flow rate value calculated from the first function f ₁ (ΔC) and the deviation amount d1 of the second flowmeter 48, and the raw fuel gas calculated from the second function f ₂ (ΔC) of the second flow meter 48 and the deviation amount d2 and the average value (=(F1-d1+F2-d2)/2) of the flow rate value may be calculated as the true value Ft of the flow rate.

Subsequently, the CPU 81 adds the specific heat difference ΔCx calculated in step S120 to the specific heat C ₀ of the standard gas obtained in advance, and obtains the specific heat Cx (=C ₀ ) of the raw fuel gas flowing through the raw fuel gas supply pipe 41 . +ΔCx) is calculated (step S150), and the gas type of the raw fuel gas flowing through the raw fuel gas supply pipe 41 is determined based on the calculated specific heat ratio Cx and a gas type table (not shown) created in advance and stored in the ROM 82. is specified (step S160). The gas type table associates the gas type of the raw fuel gas with the specific heat ratio, and in step S160, the CPU 81 identifies the gas type corresponding to the specific heat ratio ΔCx from the gas type table.

Furthermore, the CPU 81 compares the gas type specified in step S160 with the control gas type set at that time to determine whether the gas type has changed (step S170). If it is determined that there has been a change (step S170: YES), the gas type corresponding to the specific heat ratio ΔCx is set as the control gas type (step S180). If a negative determination is made in step S170, the CPU 81 skips step S180. Further, the gas type table may associate gas companies, regions, and specific heats in addition to gas types.

After the process of step S170 or S180, the CPU 81 sets the target flow rate of the raw fuel gas supplied from the raw fuel gas supply system 40 to the reformer 34 (vaporizer 33) (step S190). In step S190, the CPU 81 calculates the amount of heat according to the separately set target current value of the fuel cell FCS and the specific heat predetermined for the control gas type (the gas type, that is, the composition of the raw fuel gas). After that, the target flow rate of the raw fuel gas is calculated according to the calorific value.

Furthermore, the CPU 81 determines the detection values of the first and second flowmeters 47 and 48 from the true value Ft of the flow rate calculated in step S140, the target flow rate set in step S190, and the relational expression of the feedback control. Based on this, the target duty ratio of the raw fuel gas pump 44 is set so that the true value Ft of the flow rate calculated in step S140 matches the target flow rate set in step S190 (step S200). Then, the CPU 81 controls (feeds back control) the raw fuel gas pump 44 based on the target duty ratio set in step S200 (step S210), temporarily terminates this routine, and when the next execution timing arrives, , the routine of FIG. 3 is executed again.

As a result of executing the routine of FIG. 3 as described above, in the fuel cell system 10, the raw fuel gas flows from the raw fuel supply source 1 toward the reformer 34 (vaporizer 33) through the raw fuel gas supply pipe 41. is calculated with high accuracy. That is, the first and second flowmeters 47 and 48 of the fuel cell system 10 measure the specific heat having a correlation with the composition of the raw fuel gas flowing through the raw fuel gas supply pipe 41 in the deviation amount d of the detected value from the true value of the flow rate. The first and second flowmeters 47 and 48 measure the specific heat difference ΔC between the standard gas and the raw fuel gas supplied to the reformer 34 and the amount of deviation d. First or second functions f ₁ (ΔC) and f ₂ (ΔC) are defined to indicate the relationship between Also, the first and second flowmeters 47 and 48 basically output different values as the flow rate of the raw fuel gas having a certain composition. Furthermore, the difference ΔF between the detection values of the first and second flowmeters 47 and 48 is calculated from the deviation amount d1 of the first flowmeter 47 determined from the first function f ₁ (ΔC) and the second function f ₂ (ΔC). It matches the difference from the deviation amount d2 of the second flow meter 48 which is determined.

Therefore, the detection values F1 and F2 of the first and second flowmeters 47 and 48 (the difference ΔF between the two), the first function f ₁ (ΔC) indicating the characteristics of the first flowmeter 47, and the second flowmeter 48 At least one of the deviation amounts d1 and d2 of the detection values F1 and F2 of the first and second flowmeters 47 and 48 can be calculated from the second function f ₂ (ΔC) showing the characteristics of (Steps S110-S130). More specifically, the difference ΔF between the detection values F1 and F2 of the first and second flowmeters 47 and 48 and the deviation amount d1 obtained from the first and second functions f ₁ (ΔC) and f ₂ (ΔC) , _d2 , the deviation amounts _d1 , d2 At least one of the above can be calculated with high accuracy. Then, from at least one set of the detection value F1 and the deviation amount d1 of the first flow meter 47 and the detection value F2 and the deviation amount d2 of the second flow meter 48, the raw fuel gas supplied to the reformer 34 can be accurately calculated (step S140).

As a result, in the fuel cell system 10, even when the composition of the raw fuel gas changes, the flow rate of the raw fuel gas supplied to the reformer 34 can be accurately obtained by the control device 80 as the arithmetic processing unit. Therefore, the anode gas can be accurately supplied from the reformer 34 to each fuel cell stack FCS as required. As a result, even if the composition of the raw fuel gas changes, it is possible to satisfactorily suppress the deterioration of the output and durability of the fuel cell system 10 due to the excess or deficiency of the raw fuel gas.

Further, the control device 80 as a gas type identification unit identifies the gas type of the raw fuel gas supplied to the reformer 34 based on the calculated specific heat difference ΔCx and the specific heat C ₀ of the standard gas (step S160). . That is, the specific heat of the raw fuel gas has a correlation with the composition (concentration of combustible components) of the raw fuel gas, and can be obtained from the specific heat difference ΔCx and the specific heat C ₀ of the standard gas. Therefore, by calculating the specific heat difference ΔCx, the gas type of the raw fuel gas can be specified with high accuracy from the specific heat difference ΔCx and the specific heat C ₀ of the standard gas. Then, by setting the specified gas type of the raw fuel gas as the control gas type and reflecting it in the control of the fuel cell system (steps S170 and S180), the performance and durability of each fuel cell stack FCS can be improved. In addition, it is possible to further improve the accuracy of information such as the amount of heat and the amount of CO ₂ reduction displayed on the display unit of the fuel cell system 10 and the remote controller.

Furthermore, the control device 80 as a pump control unit sets the target flow rate of the raw fuel gas from the target current value of the fuel cell stack FCS and the amount of heat corresponding to the gas type (specific heat, that is, composition) of the raw fuel gas. And the raw fuel gas pump 44 is controlled so that the flow rate of the raw fuel gas calculated based on the detected values of the second flowmeters 47, 48 matches the target flow rate (steps S190-S210). As a result, the flow rate of the raw fuel gas can be accurately calculated, and the target flow rate of the raw fuel gas can be set more appropriately according to the gas type (composition) of the raw fuel gas supplied to the reformer 34. Therefore, it is possible to more accurately supply the required anode gas from the reformer 34 to each fuel cell FCS.

In the above embodiment, the first and second functions f ₁ (ΔC) and f ₂ (ΔC) of the first and second flowmeters 47 and 48 are both linear functions, but are not limited to this. do not have. That is, at least one of the first and second functions f ₁ (ΔC) and f ₂ (ΔC) is determined by the specific heat difference ΔC (composition) between the standard gas and the raw fuel gas supplied to the reformer 34 and the deviation Any function other than a linear function, such as a function of two or more degrees, may be used as long as it indicates the relationship with the quantity d.

FIG. 4 is a schematic configuration diagram showing another fuel cell system 10B of the present disclosure. Among the constituent elements of the fuel cell system 10B, the same elements as those of the above-described fuel cell system 10 are given the same reference numerals, and overlapping descriptions are omitted.

The fuel cell system 10B shown in FIG. 4 incorporates a third flowmeter 49 in addition to the first and second flowmeters 47 and 48 to the raw fuel gas supply pipe 41 of the fuel cell system 10 described above. corresponds to The amount of deviation d of the detected value from the true value of the flow rate of the third flowmeter 49 is also approximately proportional to the specific heat difference ΔC between the standard gas whose composition is known and the raw fuel gas flowing through the raw fuel gas supply pipe 41. It is configured to change with time. Also, as shown in FIG. 5, the first, second and third flowmeters 47, 48 and 49 of the fuel cell system 10B have different characteristics of change in the deviation d with respect to the specific heat difference .DELTA.C. Furthermore, the relationship between the specific heat difference ΔC and the amount of deviation d in the third flow meter 49 is represented by the third function f ₃ (ΔC) shown in the following equation (5). However, "a ₃ " and "b ₃ " in equation (5) are both predetermined constants, and the constant a ₃ satisfies a ₃ ≠a ₁ ≠a ₂ ≠0. Also _, the constant b3 may be zero or a real number other than zero. Furthermore, although b ₁ ≠b ₂ ≠b ₃ in the example shown in FIG. 5, any two or all of the constants b ₁ , b ₂ and b ₃ may be the same.

d=f ₃ (ΔC)=a ₃ ΔC+b ₃ (5)

_In the fuel cell system 10B including such three flowmeters 47, 48, 49, as shown in FIG. The deviation amount d1 of the first flow meter 47 determined from the first function f ₁ (ΔC) of the first flow meter 47 and the second flow meter 48 determined from the second function f ₂ (ΔC ) of the second flow meter 48 and the amount of deviation d2. Further, the difference ΔF ₁₃ between the detection values F1 and F3 of the first and third flowmeters 47 and 49 is the deviation amount of the first flowmeter 47 determined from the first function f ₁ (ΔC) of the first flowmeter 47. It matches the difference between d1 and the deviation amount d3 of the third flow meter 49 determined from the third function f ₃ (ΔC) of the third flow meter 49 . Further, the difference ΔF ₂₃ between the detected values F2 and F3 of the second and third flowmeters 48 and 49 is the deviation amount of the second flowmeter 48 determined from the second function f ₂ (ΔC) of the second flowmeter 48. It matches the difference between d2 and the deviation amount d3 of the third flow meter 49 determined from the third function f ₃ (ΔC) of the third flow meter 49 .

Therefore, in the fuel cell system 10B, from the relationships ΔF ₁₂ =F2-F1=d2-d1, ΔF ₁₃ =F1-F3=d1-d3, and ΔF ₂₃ =F2-F3=d2-d3, the standard gas and the reformed gas After obtaining three values as the specific heat difference ΔCx with the raw fuel gas supplied to the vessel 34, the average value of the three values is set as the value of the specific heat difference ΔCx, so that the first, second and second It is possible to calculate the specific heat difference ΔCx more accurately while reducing the influence of detection errors of the three flowmeters 47 , 48 , 49 . Further, in the fuel cell system 10B, based on the maximum value among the difference ΔF ₁₂ between the detection values F1 and F2, the difference ΔF ₁₃ between the detection values F1 and F3, and the difference ΔF ₂₃ between the detection values F2 and F3, Calculation of the specific heat difference ΔCx may reduce the influence of detection errors of the first, second and third flowmeters 47, 48 and 49 even when the specific heat difference ΔCx is calculated in this way.

Thereby, the accurately calculated specific heat difference ΔCx, at least one of the first, second and third functions f ₁ (ΔC), f ₂ (ΔC), and f ₃ (ΔC), and the detected values F1, From any one of F2 and F2, the true value Ft of the flow rate of the raw fuel gas supplied to the reformer 34 can be calculated more accurately. Further, in the fuel cell system 10B, from the specific heat difference ΔCx and the first, second and third functions f ₁ (ΔC), f ₂ (ΔC) and f ₃ (ΔC), the first, second and third All of the deviation amounts d1, d2, and d3 of the flow meters 47, 48, and 49 are calculated, and the flow rate value of the raw fuel gas calculated from the first function f ₁ (ΔC) of the first flow meter 47 and the deviation amount d1 , the flow rate value of the raw fuel gas calculated from the second function f ₂ (ΔC) of the second flow meter 48 and the deviation amount d2, and the third function f ₃ (ΔC) of the third flow meter 49 and the deviation amount d3 It is also possible to calculate an average value of the flow rate value of the raw fuel gas calculated from , as the true value Ft of the flow rate.

As a result, in the fuel cell system 10B, the accuracy of calculation of the flow rate of the raw fuel gas by the controller 80 can be further improved while reducing the influence of the detection errors of the first, second and third flowmeters 47, 48 and 49. becomes possible. Further, by improving the calculation accuracy of the specific heat difference ΔCx, it is possible to improve the accuracy of specifying the gas type by the control device 80 . From these points, it will be understood that the raw fuel gas supply pipe 41 may incorporate four or more flowmeters. Furthermore, in the fuel cell system 10B as well, the first, second and third functions f ₁ (ΔC) and f ₂ (ΔC) of the first, second and third flowmeters 47, 48 and 49 are f ₃ (ΔC), both of which are linear functions, but are not limited thereto. That is, at least one of the first, second and third functions f ₁ (ΔC), f ₂ (ΔC), and f ₃ (ΔC) is a combination of the standard gas and the raw material supplied to the reformer 34. Any function other than the linear function, such as a second or higher order function, may be used as long as it indicates the relationship between the specific heat difference ΔC (composition) with the fuel gas and the amount of deviation d.

As described above, the fuel cell system 10 of the present disclosure includes a fuel cell stack FCS including a plurality of single cells SC that generate power through an electrochemical reaction between an anode gas and a cathode gas; A reformer 34 that generates gas, first and second flowmeters 47 and 48 that detect the flow rate of the raw fuel gas supplied to the reformer 34, respectively, and control as an arithmetic processing unit and a gas type identification unit device 80; The first and second flowmeters 47 and 48 are configured such that the amounts of deviation d1 and d2 of the detected values F1 and F2 with respect to the true value of the flow rate respectively change according to the composition of the raw fuel gas, that is, the specific heat difference ΔC. , the change characteristics of the deviation amounts d1 and d2 of the first and second flowmeters 47 and 48 with respect to the composition of the raw fuel gas are different from each other. Furthermore, the control device 80 as an arithmetic processing unit provides first and second functions f ₁ (ΔC) and f ₂ (ΔC) that indicate the characteristics of the first and second flowmeters 47 and 48 and detection values F1 and F2. Based on this, at least one of the deviation amounts d1 and d2 of the detection values F1 and F2 of the first and second flow meters 47 and 48 is calculated (steps S110 to S130), and the detection value F1 of the first flow meter 47 and The flow rate of the raw fuel gas to be supplied to the reformer 34 is calculated from at least one set of the amount of deviation d1, the detection value F2 of the second flow meter 48, and the amount of deviation d2 (step S140). In addition, the control device 80 as a gas type identification unit controls the specific heat difference ΔCx calculated based on the first and second functions f ₁ (ΔC) and f ₂ (ΔC) and the detection values F1 and F2 and the specific heat C of the standard gas. ₀ , the gas type of the raw fuel gas to be supplied to the reformer 34 is specified (steps S160 to S180). As a result, even when the composition of the raw fuel gas changes, it is possible to satisfactorily suppress the deterioration of the output and durability of the fuel cell system 10 due to the excess or deficiency of the raw fuel gas.

It goes without saying that the invention of the present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the present disclosure. Furthermore, the above-described embodiment is merely one specific form of the invention described in the Summary of the Invention column, and does not limit the elements of the invention described in the Summary of the Invention column.

INDUSTRIAL APPLICABILITY The invention of the present disclosure can be used in the manufacturing industry of fuel cell systems and the like.

1 raw fuel supply source, 2 system power supply, 3 power line, 4 load, 10, 10B fuel cell system, 20 power generation unit, 22 housing, 24 ventilation fan, 30 power generation module, 31 module case, 32 manifold, 33 vaporizer , 34 reformer, 35 combustion unit, 36 ignition heater, 37 temperature sensor, 40 raw fuel gas supply system, 41 raw fuel gas supply pipe, 42 raw fuel gas supply valve, 44 raw fuel gas pump, 45 desulfurizer, 46 pressure sensor, 47 first flow meter, 48 second flow meter, 49 third flow meter, 50 cathode gas supply system, 51 cathode gas supply pipe, 52 air filter, 53 blower, 54 flow switch, 55 reformed water supply system, 56 reformed water supply pipe, 57 reformed water tank, 58 reformed water pump, 60 exhaust heat recovery system, 61 circulation pipe, 62 heat exchanger, 63 circulation pump, 64 radiator, 65 radiator fan, 66 electric heater, 67 Thermistor 68 Exhaust pipe 71 Power conditioner 72 Power supply board 80 Control device 81 CPU 82 ROM 83 RAM 310 Cathode gas passage 320 Anode gas passage FCS Fuel cell stack SC Single cell.

Claims (8)

A fuel cell system including a fuel cell that generates electricity through an electrochemical reaction between an anode gas and a cathode gas, and a reformer that reforms raw fuel gas to generate the anode gas,
A plurality of flowmeters each detecting the flow rate of the raw fuel gas supplied to the reformer, wherein the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas. and a plurality of flowmeters having different characteristics of change in the amount of deviation with respect to the composition,
calculating the deviation amount of at least one of the flow meters based on the characteristics and the detected values of the plurality of flow meters, and calculating the deviation amount and the detection of the at least one flow meter an arithmetic processing unit that calculates the flow rate of the raw fuel gas supplied to the reformer from the value of
a fuel cell system. In the fuel cell system according to claim 1,
For each of the plurality of flowmeters, the relationship between the specific heat difference between the standard gas, which is the raw fuel gas whose composition is known, and the raw fuel gas supplied to the reformer, and the amount of deviation is calculated. A function is specified to indicate
The arithmetic processing unit calculates the specific heat difference based on the function and the detected value of the plurality of flowmeters, and calculates the specific heat difference from the calculated specific heat difference and the function of at least one of the flowmeters. A fuel cell system that calculates the amount of deviation. In the fuel cell system according to claim 2,
The fuel cell system, wherein the arithmetic processing unit calculates the specific heat difference from the difference between the detection values of the plurality of flowmeters and the difference between the deviation amounts obtained from the function. In the fuel cell system according to claim 2 or 3,
The fuel cell system, wherein the arithmetic processing unit specifies a gas type of the raw fuel gas to be supplied to the reformer based on the specific heat difference and the specific heat of the standard gas. 5. The fuel processing system of claim 4, wherein
a raw fuel gas pump that supplies the raw fuel gas to the reformer;
A pump control unit that controls the raw fuel gas pump,
The pump control unit sets a target flow rate of the raw fuel gas from a heat amount corresponding to a target current value of the fuel cell and the gas type of the raw fuel gas, and sets a target flow rate of the raw fuel gas calculated by the arithmetic processing unit. A fuel cell system for controlling the raw fuel gas pump so that the flow rate of the fuel gas matches the target flow rate. A raw fuel gas flow rate measuring method for measuring the flow rate of raw fuel gas supplied to a reformer that generates anode gas of a fuel cell, comprising:
By means of a plurality of flowmeters each configured such that the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas, and the characteristics of the variation of the amount of deviation with respect to the composition are different from each other. , detecting the flow rate of the raw fuel gas supplied to the reformer;
calculating the amount of deviation of at least one of the flow meters based on the characteristics and the detected values of the plurality of flow meters, and calculating the amount of deviation and the detected value of the at least one of the flow meters; calculating the flow rate of the raw fuel gas supplied to the reformer from
A method for measuring the flow rate of raw fuel gas. A fuel cell system including a fuel cell that generates electricity through an electrochemical reaction between an anode gas and a cathode gas, and a reformer that reforms raw fuel gas to generate the anode gas,
A plurality of flowmeters each detecting the flow rate of the raw fuel gas supplied to the reformer, wherein the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas. and a plurality of flowmeters having different characteristics of change in the amount of deviation with respect to the composition,
A function defined for each of the plurality of flowmeters, which is a difference in specific heat between a standard gas which is the raw fuel gas whose composition is known and the raw fuel gas supplied to the reformer; calculating the specific heat difference based on a function indicating the relationship between the amount of deviation and the detection values of the plurality of flow meters, and calculating the specific heat difference based on the calculated specific heat difference and the specific heat of the standard gas in the reformer; a gas type identification unit that identifies the gas type of the raw fuel gas to be supplied to the
a fuel cell system. A gas type identification method for a raw fuel gas for identifying a gas type of a raw fuel gas to be supplied to a reformer that generates an anode gas of a fuel cell, comprising:
With a plurality of flowmeters each configured so that the amount of deviation of the detected value from the true value of the flow rate varies according to the composition of the raw fuel gas, and the characteristics of the change in the amount of deviation with respect to the composition are different from each other, detecting the flow rate of the raw fuel gas supplied to the reformer;
A function defined for each of the plurality of flowmeters, which is a difference in specific heat between a standard gas which is the raw fuel gas whose composition is known and the raw fuel gas supplied to the reformer; calculating the specific heat difference based on a function indicating the relationship between the amount of deviation and the detection values of the plurality of flow meters, and calculating the specific heat difference based on the calculated specific heat difference and the specific heat of the standard gas in the reformer; Identifying the gas type of the raw fuel gas supplied to
Gas type identification method of raw fuel gas.

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