Method of setting fuel cell system

Abstract

To properly cope with composition variation of raw fuel gas due to an installation area of a fuel cell system.SOLUTION: A flow rate sensor capable of detecting a flow rate of the raw fuel gas in the raw fuel gas supply path, a detection value of the flow rate sensor changing in accordance with a gas composition of the raw fuel gas, and setting a target fuel flow rate so that a fuel utilization rate becomes a target utilization rate based on a target current of the fuel cell stack; In a setting method for a fuel cell system including a control unit that controls a gas pump such that a fuel flow rate based on a detection value of a flow rate sensor becomes a target fuel flow rate, gas-related information including a variation range of a gas composition of a raw fuel gas in an installation area of the fuel cell system is acquired, and at least a target utilization rate is set based on the gas-related information.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This specification discloses a method for configuring a fuel cell system. [Background technology]

[0002] Conventionally, fuel cell systems that generate electricity by receiving a supply of fuel gas have been proposed. For example, Patent Document 1 describes a system that includes a fuel flow meter that detects the amount of fuel supplied and a sensor that detects oxygen or nitrogen in the fuel. Based on the sensor's detection value, the system corrects for errors in the fuel flow meter's detection value to obtain the amount of fuel containing air and calculates the amount of air contained in the fuel. Patent Document 2 also describes a system that includes a fuel gas dew point temperature measurement means, a calculation means that estimates the raw fuel flow rate or steam (raw water) flow rate based on the dew point temperature, and a flow rate adjustment means that adjusts the raw fuel flow rate or steam flow rate based on the calculation result, and detects and takes action when the raw fuel or steam flow rate deviates from a set value. Patent Document 3 also describes a system that includes multiple fuel flow meters whose detected values ​​deviate from the true flow rate depending on the composition of the raw fuel gas and whose change characteristics are different from one another. The system calculates the deviation of at least one flow meter based on the detection values ​​of the multiple flow meters, and calculates the raw fuel gas flow rate from the calculated deviation and the detection value of the at least one flow meter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-169214 [Patent Document 2] Patent No. 4038390 [Patent Document 3] Japanese Patent Publication No. 2020-013720 Summary of the Invention [Problem to be solved by the invention]

[0004] Although the above-mentioned Patent Documents 1 to 3 can deal with changes (deviations) in flow rate due to fluctuations in the composition of the raw fuel gas, they require sensors, dew point temperature measuring means, and multiple flow meters, which leads to an increase in the size and cost of the fuel cell system.In addition, composition fluctuations such as the composition of the raw fuel gas and its fluctuation range can vary greatly depending on the installation area of ​​the fuel cell system, so it is necessary to deal with these appropriately.

[0005] The main object of the present disclosure is to appropriately deal with variations in the composition of raw fuel gas depending on the installation area of ​​the fuel cell system. [Means for solving the problem]

[0006] The present disclosure has adopted the following means to achieve the above-mentioned main object.

[0007] The fuel cell system setting method of the present disclosure includes: a fuel cell stack that generates electricity based on the anode gas and the cathode gas; a reforming unit that reforms a raw fuel gas to generate the anode gas; a raw fuel gas supply device that supplies the raw fuel gas to the reforming unit through a raw fuel gas supply path by driving a gas pump; a flow rate sensor capable of detecting a flow rate of the raw fuel gas in the raw fuel gas supply path, the detected value of which changes depending on the gas composition of the raw fuel gas; a control unit that sets a target current for the fuel cell stack, sets a target fuel flow rate based on the target current so that the fuel utilization rate of the fuel cell stack becomes the target utilization rate, and controls the gas pump so that the fuel flow rate based on the detection value of the flow rate sensor becomes the target fuel flow rate; A method for setting up a fuel cell system comprising: The gist of the present invention is to acquire gas-related information including a fluctuation range of the gas composition of the raw fuel gas in the installation area of ​​the fuel cell system, and to set at least the target utilization rate based on the gas-related information.

[0008] The fuel cell system setting method disclosed herein acquires gas-related information including the range of fluctuation in the gas composition of the raw fuel gas in the installation area of ​​the fuel cell system, and sets at least a target utilization rate based on the gas-related information. Therefore, even without adding a special component for detecting fluctuations in the raw fuel gas composition, it is possible to appropriately set a target utilization rate according to the gas-related information in the installation area and stabilize the operation of the fuel cell system. Therefore, it is possible to appropriately respond to fluctuations in the raw fuel gas composition depending on the installation area of ​​the fuel cell system. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a fuel cell system 10. FIG. [Figure 2] FIG. 2 is an explanatory diagram showing an example of fluctuation in gas composition. [Figure 3] FIG. 10 is an explanatory diagram showing an example of a setting method. [Figure 4] FIG. 4 is an explanatory diagram showing an example of gas-related information and setting values. [Figure 5] FIG. 4 is an explanatory diagram showing an example of a change in fuel utilization rate Uf over time. [Figure 6] FIG. 4 is an explanatory diagram showing an example of a change in fuel utilization rate Uf over time. [Figure 7] FIG. 4 is an explanatory diagram showing an example of a change in fuel utilization rate Uf over time. [Figure 8] FIG. 4 is an explanatory diagram showing an example of a change in fuel utilization rate Uf over time. [Figure 9] FIG. 2 is an explanatory diagram showing an example of the relationship between the power generation amount W, the stack temperature Ts, and the fuel utilization rate Uf. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of a fuel cell system 10. As shown in the figure, the fuel cell system 10 of this embodiment includes a power generation module 20 including a fuel cell stack 21 that generates power through an electrochemical reaction between hydrogen in an anode gas and oxygen in a cathode gas, a raw fuel gas supply device 30 that supplies a raw fuel gas (e.g., natural gas or LP gas) that serves as a raw material for the anode gas to the power generation module 20, a reforming water supply device 40 that supplies reforming water necessary for reforming (steam reforming) the raw fuel gas to the power generation module 20, an air supply device 50 that supplies air as a cathode gas to the power generation module 20 (fuel cell stack 21), an exhaust heat recovery device 60 that recovers exhaust heat generated in the power generation module 20, and a control device 100 that controls the entire system.

[0011] The power generation module 20 includes a fuel cell stack 21, a vaporizer 22, a reformer 23, a combustor 24, and a plurality of (two) heat exchangers 26 and 27, all of which are housed in a module case 29 having thermal insulation properties.

[0012] The fuel cell stack 21 comprises a plurality of solid oxide type unit cells, each having an electrolyte such as zirconium oxide and an anode and cathode sandwiching the electrolyte. An anode gas passage through which an anode gas flows is connected to the anode of each unit cell. A cathode gas passage through which a cathode gas flows is connected to the cathode of each unit cell. A temperature sensor 112 is installed near the fuel cell stack 21. The temperature sensor 112 detects the temperature of the fuel cell stack 21 (stack temperature Ts).

[0013] The vaporizer 22 and reformer 23 of the power generation module 20 are disposed above the fuel cell stack 21 within the module case 29 at a distance. In addition, a combustor 24 is disposed between the fuel cell stack 21 and the vaporizer 22 and reformer 23 to generate heat required for the operation of the fuel cell stack 21 and the reactions in the vaporizer 22 and reformer 23.

[0014] The vaporizer 22 heats the raw fuel gas from the raw fuel gas supply device 30 and the reforming water from the reforming water supply device 40 using heat from the combustor 24, preheating the raw fuel gas and evaporating the reforming water to generate steam. The raw fuel gas preheated by the vaporizer 22 is mixed with steam, and the mixed gas flows from the vaporizer 22 into the reformer 23. In addition, a temperature sensor 111 is installed near the inlet of the reformer 23 to detect the temperature of the mixed gas flowing into the reformer 23.

[0015] The reformer 23 has a Ru-based or Ni-based reforming catalyst filled therein, and generates hydrogen gas and carbon monoxide by a reaction (steam reforming reaction) of the mixed gas from the vaporizer 22 with the reforming catalyst in the presence of heat from the combustor 24. The reformer 23 also generates hydrogen gas and carbon dioxide by a reaction (carbon monoxide shift reaction) between the carbon monoxide generated in the steam reforming reaction and steam. As a result, the reformer 23 generates anode gas containing hydrogen, carbon monoxide, carbon dioxide, steam, unreformed raw fuel gas, etc. The anode gas generated by the reformer 23 flows through the anode gas piping 71 into the anode gas passage of each unit cell and is supplied to the anode.

[0016] Air as a cathode gas flows into the cathode gas passage of each unit cell through a cathode gas pipe 72 and is supplied to the cathode. In the cathode of each unit cell, oxide ions (O 2- ) are produced, and the oxide ions pass through the electrolyte and react with hydrogen and carbon monoxide at the anode to generate electrical energy.

[0017] Anode gas (hereinafter referred to as "anode offgas") not used in the electrochemical reaction (power generation) in each unit cell is supplied to the condenser 62 through an anode offgas pipe 73, where it is cooled to remove at least a portion of the water vapor contained in the anode offgas, and then supplied to the combustor 24 through an anode offgas pipe 74. A heat exchanger 26 is provided in the anode offgas pipes 73, 74, and the anode offgas flowing through the anode offgas pipe 74 (anode offgas after passing through the condenser 62) is heated in the heat exchanger 26 by heat exchange with high-temperature anode offgas (anode offgas before passing through the condenser 62) flowing from the fuel cell stack 21 through the anode offgas pipe 73. Cathode gas (hereinafter referred to as "cathode offgas") not used in the electrochemical reaction (power generation) in each unit cell is supplied to the combustor 24 through a cathode offgas pipe 75.

[0018] The anode off-gas that flows into the combustor 24 is a combustible gas containing fuel components such as hydrogen and carbon monoxide, and by combusting it with the cathode off-gas that contains oxygen that flows into the combustor 24, heat is generated that is necessary for operating the fuel cell stack 21, preheating the raw fuel gas and generating steam in the vaporizer 22, and the steam reforming reaction in the reformer 23. The combustor 24 also generates combustion exhaust gas that contains unburned fuel, and this combustion exhaust gas passes through the combustion exhaust gas piping 76, the heat exchanger 27, and the combustion catalyst 28 before being discharged into the outside air. The combustion catalyst 28 is an oxidation catalyst for re-burning the unburned fuel in the combustion exhaust gas.

[0019] The raw fuel gas supply device 30 includes a raw fuel gas supply pipe 31 that connects a raw fuel supply source 1 that supplies raw fuel gas to a vaporizer 22, and on-off valves (dual valves) 32 and 33, a gas pump 36, and a desulfurizer 38 that are installed in the raw fuel gas supply pipe 31. By operating the gas pump 36, the raw fuel gas is pressure-fed (supplied) from the raw fuel supply source 1 to the vaporizer 22 via the desulfurizer 38. In addition, a gas flow sensor 39 is installed in the raw fuel gas supply pipe 31 to detect the flow rate per unit time of the raw fuel gas flowing through the raw fuel gas supply pipe 31 (fuel flow rate Fg).

[0020] The gas flow sensor 39 is a flow meter (mass flow meter) that depends on the composition of the fluid to be detected, and a thermal mass flow meter is used, for example. A thermal mass flow meter utilizes the fact that the amount of heat absorbed by the fluid from the thermal flow meter (heating element) is proportional to the mass flow rate of the fluid. Since the detected value (output voltage) is proportional to the mass flow rate of the raw fuel gas, the mass flow rate can be measured based on the detected value (output voltage). However, the amount of heat absorbed by the fluid varies depending on the composition of the fluid, and the detected value of the gas flow sensor 39 includes a component proportional to the mass flow rate and a component dependent on the gas composition of the raw fuel gas. Therefore, the detected value of the gas flow sensor 39 deviates from the true value depending on the gas composition of the raw fuel gas, and therefore the detected value must be corrected.

[0021] The reforming water supply device 40 has a reforming water tank 42 that stores reforming water, a reforming water supply pipe 41 that connects the reforming water tank 42 and the vaporizer 22, and a reforming water pump 43 installed in the reforming water supply pipe 41. When the reforming water pump 43 is operated, the reforming water in the reforming water tank 42 is pressure-fed (supplied) to the vaporizer 22 by the reforming water pump 43. A reforming water flow rate sensor 45 is installed in the reforming water supply pipe 41 to detect the flow rate per unit time of the reforming water flowing through the reforming water supply pipe 41 (reforming water flow rate Fw).

[0022] The air supply device 50 has an air supply pipe 51 connected to a cathode gas pipe 72 installed inside the module case 29, an air filter 52 provided at the inlet of the air supply pipe 51, and an air pump 53 installed in the air supply pipe 51. By operating the air pump 53, air as cathode gas is sucked into the air supply pipe 51 through the air filter 52 and is pressure-fed (supplied) to the fuel cell stack 21 (cathode) through the cathode gas pipe 72. The air flowing through the cathode gas pipe 72 is heated by heat exchange in the heat exchanger 27 with high-temperature combustion exhaust gas flowing through the combustion exhaust gas pipe 76.

[0023] The exhaust heat recovery device 60 includes a hot water storage tank 61 that stores hot water, a condenser 62 that exchanges heat between the hot water and anode off-gas flowing from the fuel cell stack 21 through an anode off-gas piping 73 and condenses the water vapor contained in the anode off-gas, a circulation piping 63 connected to the hot water storage tank 61 and the condenser 62, and a circulation pump 64 incorporated in the circulation piping 63. The hot water stored in the hot water storage tank 61 is introduced into the condenser 62 by operating the circulation pump 64, where it is heated by heat exchange with the anode off-gas and then returned to the hot water storage tank 61.

[0024] Furthermore, a condensed water pipe 44 and an anode off-gas pipe 74 are connected to the passage outlet on the anode off-gas side of the condenser 62, and the condensed water obtained by condensing the water vapor in the anode off-gas through heat exchange with hot water from the hot water storage tank 61 is introduced into the reforming water tank 42 through the condensed water pipe 44. The reforming water tank 42 is equipped with a water purifier (not shown) that purifies the condensed water that has passed through the condensed water pipe 44. As described above, the anode off-gas from which the water vapor has been removed in the condenser 62 is supplied to the combustor 24 through the anode off-gas pipe 74.

[0025] An input terminal of a power conditioner 80 is connected to an output terminal of the fuel cell stack 21, and the output terminal of the power conditioner 80 is connected via a relay to a power line 3 from the power grid 2 to a load 4. The power conditioner 80 has a DC / DC converter that converts the DC power output from the fuel cell stack 21 into DC power of a predetermined voltage (e.g., DC 250 V to 300 V), and an inverter that converts the converted DC power into AC power of a voltage (e.g., AC 200 V) that can be connected to the power grid. This makes it possible to convert the DC power from the fuel cell stack 21 into AC power and supply it to a load 4 such as a home appliance. A power supply board 81 is connected to the power conditioner 80. The power supply board 81 converts DC power from the fuel cell stack 21 and AC power from the power system 2 into low-voltage DC power and supplies it to auxiliary equipment such as the gas pump 36, the reforming water pump 43, the air pump 53, and the circulation pump 64, sensors such as the gas flow sensor 39, the reforming water flow sensor 45, temperature sensors 111 and 112, the current sensor 113, and the voltage sensor 114, and the control device 100. In addition, a cooling fan and a ventilation fan (not shown) for cooling the power conditioner 80 and the power supply board 81 are disposed in the auxiliary equipment room where the power conditioner 80 and the power supply board 81 are disposed. The cooling fan sends air to heat-generating parts of the power conditioner 80 and the power supply board 81, cooling the heat-generating parts by heat exchange with the air. The air that has been heated by cooling the heat-generating parts is discharged into the atmosphere by the ventilation fan.

[0026] The control device 100 is configured as a microprocessor centered around a CPU 101, and in addition to the CPU 101, is equipped with a ROM 102 that stores processing programs, a RAM 103 that temporarily stores data, an EEPROM 104 as non-volatile memory, and input / output ports (not shown). Various detection signals are input to the control device 100 via input ports from a current sensor 113 that detects the current (stack current Ist) output from the fuel cell stack 21, a voltage sensor 114 that detects the voltage (stack voltage Vst) output from the fuel cell stack 21, a gas flow sensor 39, a reforming water flow sensor 45, temperature sensors 111, 112, etc. Furthermore, the control device 100 outputs various control signals via output ports to the solenoids of the on-off valves 32, 33, the pump motor of the gas pump 36, the pump motor of the reforming water pump 43, the pump motor of the air pump 53, the pump motor of the circulation pump 64, etc.

[0027] A remote control 105 is communicatively connected to the control device 100 via a wireless or wired communication line. The control device 100 performs various settings and controls based on signals from the remote control 105 operated by an operator such as an installer or user of the fuel cell system 10. When the remote control 105 receives various information such as operation information of the fuel cell system 10 from the control device 100, it displays the information on a display panel of the remote control 105. The control device 100 also includes setting switches 106 such as dip switches or rotary switches. In the fuel cell system 10, the setting switches 106 can be used to set settings as described below.

[0028] In the fuel cell system 10 of this embodiment configured as described above, power generation control is performed by setting a target current Itag according to the required power generation amount (power generation output) within the range of the maximum power generation amount Wmax, and controlling the supply amounts of raw fuel gas, reforming water, and air so that the target current Itag is output from the fuel cell stack 21. The supply control of raw fuel gas is performed by setting a target fuel flow rate Fgtag based on the target current Itag using the following equation (1) so that the fuel utilization factor Uf becomes the target utilization factor Uftag, and by controlling the gas pump 36 so that the fuel flow rate Fg based on the detection value of the gas flow sensor 39 becomes the target fuel flow rate Fgtag. The fuel utilization factor Uf is the proportion of raw fuel gas supplied to the power generation module 20 that is actually used for power generation. In equation (1), "S" is the number of cells in the fuel cell stack 21, "22.4" is the volume of one mole of gas at 0°C and 1 atmosphere, "60" is time [sec], "V" is the ionic valence, and "96485" is Faraday's constant [C / mol]. The supply of reforming water is controlled by setting a target reforming water flow rate Fwtag using the following equation (2) so that the steam-carbon ratio SC in the reformer 23 becomes the target ratio SCtag, and controlling the reforming water pump 43 so that reforming water is supplied at the set target reforming water flow rate Fwtag. The steam-carbon ratio SC is the molar ratio of carbon contained in hydrocarbons in the raw fuel gas to steam added for steam reforming. In equation (2), "C" is the number of carbon atoms (carbon number) of hydrocarbons in the raw fuel gas, "22.4" is the volume of one mole of gas (steam) at 0°C and 1 atmosphere, and "18" is the molecular weight of water. The supply of air is controlled by setting a target air flow rate Fatag so that the stack temperature Ts detected by the temperature sensor 112 becomes the target temperature Tstag, and controlling the air pump 53 so that air is supplied at the set target air flow rate Fatag.

[0029]

number

[0030] In this way, when the supply amount of raw fuel gas is controlled by setting the target fuel flow rate Fgtag based on the target utilization rate Uftag, the power generation efficiency of the fuel cell system 10 can be further improved by making the target utilization rate Uftag as high as possible. However, even if the valence V and the carbon number C are set to values ​​corresponding to the gas composition (calorific value) of the raw fuel gas in equations (1) and (2), depending on the magnitude of the fluctuation range of the gas composition of the raw fuel gas, there may be an excess or deficiency in the supply amount of raw fuel gas, causing the fuel utilization rate Uf and the steam-to-carbon ratio SC to fluctuate greatly, which could result in an abnormality in the fuel cell system 10 (failure of the fuel cell stack 21).

[0031] The raw fuel gas supplied from the raw fuel supply source 1 may have intermittent variations in its composition. In FIG. 2, as an example of variations in gas composition throughout the year, the solid line indicates the variations in the concentration of the main components of the raw fuel gas (e.g., methane, ethane, propane, etc.), while the dotted line indicates the variations in the concentration of components other than the main components (e.g., oxygen, hydrogen, water vapor, nitrogen, etc.). The right-side vertical axis represents the concentration of the main components, and the left-side vertical axis represents the concentrations of the components other than the main components. As shown in FIG. 2, variations in gas composition occur not only due to variations in the composition ratio of the main components of the raw fuel gas, but also due to variations in components other than the main components. Such variations in gas composition and their magnitude vary depending on the type of raw fuel gas supplied, the composition ratio of the main components, and other factors, in each installation area, both domestically and internationally, where the fuel cell system 10 is installed. Furthermore, as described above, a mass flow meter is used as the gas flow sensor 39, and its detected value varies due to the influence of the gas composition. Therefore, in this embodiment, values ​​required for various controls are set and registered in the EEPROM 104 based on the gas composition (calorific value) and its fluctuation range (calorific value fluctuation range) in the installation area of ​​the fuel cell system 10.

[0032] FIG. 3 is an explanatory diagram showing an example of a setting method. This setting method may be performed by an operator or the like at a factory of the fuel cell system 10 before shipment, or may be performed by an operator or the like at the time of installation in the installation area of ​​the fuel cell system 10. Furthermore, the setting method is performed, for example, by operating a remote control 105 while a setting mode different from the operation mode is selected. In this setting method, the operator (setting person) first acquires gas-related information regarding fluctuations in the composition of the raw fuel gas in the installation area of ​​the fuel cell system 10 to be set (S100). The gas-related information includes the gas composition of the raw fuel gas in the installation area and the fluctuation range of the gas composition. Since the gas composition fluctuates as described above, for example, a representative value (e.g., average) of the gas composition may be acquired as the gas composition, and the amount of fluctuation relative to the representative value may be acquired as the fluctuation range. Furthermore, the operator may access, for example, a data server or the like that stores gas-related information for each installation area, and acquire the gas-related information for the corresponding installation area. The installation area of ​​the fuel cell system 10 may be the area where the fuel cell system 10 is planned to be installed (shipping destination) if it is before shipping, or may be an area based on the location information of the GPS function of the worker's mobile terminal if it is at the time of installation.

[0033] Next, the operator sets the Cf value (conversion factor) of the gas flow sensor 39, the target utilization factor Uftag, and the maximum power generation amount Wmax based on the acquired gas-related information (S110). The Cf value is a value for correcting the deviation of the detected value of the gas flow sensor 39 from the true value of the raw fuel gas flow rate. The operator then performs a registration operation to register the set values ​​in the EEPROM 104, thereby terminating the setting mode (S120). The CPU 101 of the control device 100 reads necessary values ​​(set values) from the EEPROM 104 and performs control in the above-mentioned power generation control. In S110, for example, the operator may set each value by referring to a map in which the Cf value, the target utilization factor Uftag, and the maximum power generation amount Wmax are previously associated with the gas composition and its fluctuation range. For example, the map may associate the Cf value according to the gas composition, the target utilization factor Uftag, and the maximum power generation amount Wmax with the fluctuation range of the gas composition. Furthermore, the operator may also refer to the map or the like to set and register values ​​for the valence V and the number of carbon atoms C in the above-described formulas (1) and (2) according to the gas composition.

[0034] An example of the settings for each installation area will be described below. FIG. 4 is an explanatory diagram showing an example of gas-related information and setting values ​​for each installation area, illustrating four installation areas, Areas 1 to 4. FIGS. 5 to 8 are explanatory diagrams showing an example of the time change of the fuel utilization factor Uf, with the horizontal axis representing time t and the vertical axis representing the fuel utilization factor Uf. Note that the time change of the fuel utilization factor Uf is not limited to periodic changes, but also includes non-periodic changes. The solid line in FIG. 7 and the dashed dotted line in FIG. 8 indicate the same time change.

[0035] The first area is a reference area in which the raw fuel gas has a reference composition and a reference fluctuation range for the gas composition. The fuel cell system 10 installed in the first area has a Cf value set to a reference Cf1, a target utilization rate Uftag set to a reference target utilization rate Uftag1, and a maximum power generation amount Wmax set to a reference maximum power generation amount Wmax1 (see FIG. 4). The reference Cf1 is a value used to correct the discrepancy between the true flow rate and the detected value of the gas flow sensor 39 when the raw fuel gas has a reference composition. When the gas composition is the reference composition, the detected value of the gas flow sensor 39 can be appropriately corrected using Cf1 to accurately obtain the fuel flow rate Fg. Furthermore, the reference target utilization rate Uftag1 is set to as high a value as possible to further improve the power generation efficiency of the fuel cell system 10. The reference maximum power generation amount Wmax1 is, for example, the maximum (upper limit) power generation amount that the fuel cell system 10 can stably output, and is determined based on system specifications, etc.

[0036] Furthermore, since the fluctuation range of the gas composition in the first area is within the reference range, even if the fuel utilization rate Uf fluctuates relative to the target utilization rate Uftag1 due to fluctuations in the gas composition, the fluctuation range is kept small, as shown in FIG. 5. Therefore, the fuel utilization rate Uf fluctuates at or below the upper limit utilization rate Ufmax. Here, if the fuel utilization rate Uf exceeds the upper limit utilization rate Ufmax and is high, the flow rate (true value) of the raw fuel gas becomes low, which may result in a fuel shortage and cause a breakdown or a decrease in durability of the fuel cell stack 21. In the fuel cell system 10 in the first area, the fuel utilization rate Uf does not exceed the upper limit utilization rate Ufmax, so there is almost no risk of this happening. Therefore, in the fuel cell system 10 in the first area, the supply of raw fuel gas is controlled using the reference Cf1, the reference target utilization rate Uftag1, and the reference maximum power generation amount Wmax1, thereby stabilizing the operation of the fuel cell system 10.

[0037] The second area is an area where the gas composition differs from the reference composition and the fluctuation range of the gas composition is within a reference range. Because the gas composition differs from the reference composition in the second area, the detection value of the gas flow sensor 39 deviates from the true value, and the median value of the fuel utilization factor Uf may deviate from the target utilization factor Uftag1 and exceed the upper limit utilization factor Ufmax (see the dashed-dotted line in Figure 6). However, because the fluctuation range of the gas composition is within a reference range, the fluctuation of the fuel utilization factor Uf due to fluctuations in the gas composition is the same as in the first area shown in Figure 5. In the fuel cell system 10 installed in this second area, the Cf value is set to Cf2, which is different from Cf1, the target utilization factor Uftag is set to the reference target utilization factor Uftag1, and the maximum power generation amount Wmax is set to the reference maximum power generation amount Wmax1 (see Figure 4). Note that Cf2 is appropriately determined as a value corresponding to the gas composition of the second area.

[0038] In this way, in the fuel cell system 10 in the second area, Cf2 is set according to the gas composition in the second area. Therefore, Cf2 can be used to appropriately correct the detection value of the gas flow sensor 39 to accurately obtain the fuel flow rate Fg, and the supply of raw fuel gas can be controlled so that the median value of the fuel utilization rate Uf matches the target utilization rate Uftag. Even if the fuel utilization rate Uf fluctuates due to fluctuations in the gas composition and deviates from the target utilization rate Uftag, the fluctuation range of the gas composition is within the reference range, and the fluctuation of the fuel utilization rate Uf is the same as in the first area, so the fuel utilization rate Uf can be kept below the upper limit utilization rate Ufmax (see the solid line in FIG. 6). Therefore, in the fuel cell system 10 in the second area, Cf2 according to the gas composition, the reference target utilization rate Uftag1, and the reference maximum power generation amount Wmax1 can be used to appropriately control the supply of raw fuel gas, thereby stabilizing the operation of the fuel cell system 10.

[0039] The third area is an area where the gas composition differs from the reference composition and the fluctuation range of the gas composition is larger than the reference range. Because the gas composition differs from the reference composition in the third area, the detected value of the gas flow sensor 39 deviates from the true value, and the median value of the fuel utilization factor Uf deviates from the target utilization factor Uftag1 and is likely to exceed the upper limit utilization factor Ufmax. Furthermore, because the fluctuation range of the gas composition is large, the fluctuation of the fuel utilization factor Uf due to the fluctuation of the gas composition becomes large, resulting in a large excess over the upper limit utilization factor Ufmax (see the dashed-dotted line in Figure 7). In the fuel cell system 10 installed in this third area, the Cf value is set to Cf3, which is different from Cf1, the target utilization factor Uftag is set to Uftag2, which is smaller than the target utilization factor Uftag1, and the maximum power generation amount Wmax is set to Wmax2, which is smaller than the maximum power generation amount Wmax1 (see Figure 4). Note that Cf3 is appropriately determined as a value corresponding to the gas composition of the third area.

[0040] In this way, in the fuel cell system 10 in the third area, Cf3 is set according to the gas composition in the third area, and Cf3 is used to appropriately correct the detection value of the gas flow sensor 39 to accurately obtain the fuel flow rate Fg, and the supply of raw fuel gas can be controlled so that the median value of the fuel utilization rate Uf becomes the target utilization rate Uftag1. However, because the gas composition fluctuates widely, fluctuations in the gas composition can cause the fuel utilization rate Uf to fluctuate and deviate significantly from the target utilization rate Uftag1. Therefore, even if the target utilization rate Uftag1 is targeted, the fuel utilization rate Uf may exceed the upper limit utilization rate Ufmax (see the solid line in FIG. 7 and the dashed-dotted line in FIG. 8), which could result in a breakdown or reduced durability of the fuel cell stack 21 due to a lack of fuel, as described above. Therefore, in the third area, in order to prevent the fuel utilization rate Uf from exceeding the upper limit utilization rate Ufmax even if it fluctuates, the target utilization rate Uftag2, which is smaller than the target utilization rate Uftag1, is aimed for, and the fuel utilization rate Uf is kept below the upper limit utilization rate Ufmax (see the solid line in Figure 8). Note that the greater the fluctuation range of the gas composition, the greater the fluctuation range of the fuel utilization rate Uf, so the target utilization rate Uftag is set to a smaller value as the fluctuation range of the gas composition increases. However, since the following problems may arise if the target utilization rate Uftag is set to a smaller value in the third area, a maximum power generation amount Wmax2, which is smaller than the maximum power generation amount Wmax1, is set.

[0041] FIG. 9 is an explanatory diagram showing the relationship between the power generation amount W, stack temperature Ts, and fuel utilization rate Uf. As shown in the figure, when the target utilization rate Uftag1 (see the dashed-dotted line in FIG. 9 ) is set, even when power generation control is performed at the maximum power generation amount Wmax1, the stack temperature Ts remains below the upper limit temperature Tsmax (see the dotted line in FIG. 9 ). On the other hand, if power generation control is performed by lowering the target utilization rate Uftag1 to Uftag2 (see the solid line in FIG. 9 ) while maintaining the maximum power generation amount Wmax1, the stack temperature Ts increases due to an increase in the supply amount of raw fuel gas (fuel calorific value), and there is a risk that the stack temperature Ts will exceed the upper limit temperature Tsmax, causing a malfunction of the fuel cell stack 21. Therefore, in the fuel cell system 10 in the third area, a maximum power generation amount Wmax2 smaller than the maximum power generation amount Wmax1 is set to suppress an increase in the supply amount of raw fuel gas, preventing the stack temperature Ts from exceeding the upper limit temperature Tsmax. Therefore, in the fuel cell system 10 in the third area, the supply of raw fuel gas can be appropriately controlled using Cf3 according to the gas composition, a target utilization factor Uftag2 that is smaller than the standard, and a maximum power generation amount Wmax2 that is smaller than the standard, thereby stabilizing the operation of the fuel cell system 10. As described above, the target utilization factor Uftag is set smaller the greater the fluctuation range of the gas composition, and therefore the maximum power generation amount Wmax is set smaller the greater the fluctuation range of the gas composition.

[0042] The fourth area is an area in which the gas composition is a reference composition and the fluctuation range of the gas composition is larger than the reference range. The fluctuation range of the gas composition in the fourth area is the same as that in the third area. In the fourth area, the gas composition is the reference composition, so it is possible to prevent the median value of the fuel utilization factor Uf from deviating significantly from the target utilization factor Uftag1. However, because the fluctuation range of the gas composition is large, the fluctuation of the fuel utilization factor Uf may also be large and exceed the upper limit utilization factor Ufmax. That is, as in the third area, the fuel utilization factor Uf may fluctuate significantly (see the solid line in FIG. 7 and the dashed-dotted line in FIG. 8), which may cause breakdowns or reduced durability of the fuel cell stack 21. In the fuel cell system 10 installed in this fourth area, the Cf value is set to the reference Cf1, and as in the third area, the target utilization factor Uftag is set to the target utilization factor Uftag2, and the maximum power generation amount Wmax is set to the maximum power generation amount Wmax2 (see FIG. 4). As a result, in the fuel cell system 10 in the fourth area, as in the third area, the target utilization rate Uftag2 is targeted, and even if the fuel utilization rate Uf fluctuates, it can be kept below the upper limit utilization rate Ufmax (see the solid line in Figure 8).

[0043] The fuel cell system 10 of the present embodiment described above acquires gas-related information including the range of fluctuations in the gas composition of the raw fuel gas in the installation area, and sets at least the target utilization rate Uftag based on the gas-related information. Therefore, without adding a special configuration for detecting fluctuations in the composition of the raw fuel gas, it is possible to appropriately set the target utilization rate Uftag according to the gas-related information of the installation area, thereby stabilizing the operation of the fuel cell system 10. Therefore, it is possible to appropriately respond to fluctuations in the composition of the raw fuel gas depending on the installation area of ​​the fuel cell system 10.

[0044] Furthermore, in the fuel cell system 10, the target utilization rate Uftag is set smaller as the fluctuation range of the gas composition in the gas-related information increases. Therefore, even if the fuel utilization rate Uf fluctuates due to fluctuations in the gas composition, the upper limit utilization rate Ufmax is not exceeded, thereby preventing breakdowns and deterioration of the durability of the fuel cell stack 21.

[0045] Furthermore, in the fuel cell system 10, the target current Itag is set within the range of the maximum power generation amount Wmax, and the larger the fluctuation range of the gas composition in the gas-related information, the smaller the maximum power generation amount Wmax is set. Therefore, by reducing the target utilization rate Uftag, it is possible to prevent the stack temperature Ts from exceeding the upper limit temperature Tsmax due to an increase in the supply amount of raw fuel gas. This makes it possible to prevent breakdowns and deterioration of the durability of the fuel cell stack 21.

[0046] Furthermore, in the fuel cell system 10, a Cf value is set based on the gas composition in the gas-related information to correct the detection value of the gas flow sensor 39. This makes it possible to accurately detect the fuel flow rate Fg of the raw fuel gas and appropriately control the supply of the raw fuel gas to aim for the target utilization rate Uftag.

[0047] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure.

[0048] In the above-described embodiment, the Cf value, the target utilization rate Uftag, and the maximum power generation amount Wmax are set based on gas-related information, but this is not limiting, and it is sufficient to set at least the target utilization rate Uftag. For example, even if the target utilization rate Uftag is set small, if the stack temperature Ts does not exceed the upper limit temperature Tsmax, it is not necessary to set (change) the maximum power generation amount Wmax.

[0049] In the above-described embodiment, the maximum power generation amount Wmax is set small to prevent the stack temperature Ts from exceeding the upper limit temperature Tsmax, but this is not limiting. For example, the flow rate of air supplied from the air supply device 50 may be increased to promote cooling of the fuel cell stack 21 and prevent the stack temperature Ts from exceeding the upper limit temperature Tsmax.

[0050] In the above-described embodiment, in step S110 of the setting method, the Cf value, the target utilization factor Uftag, and the maximum power generation amount Wmax are set by referring to a map in which the Cf value, the target utilization factor Uftag, and the maximum power generation amount Wmax are previously associated with the gas composition and the fluctuation range, but this is not limiting. For example, an appropriate combination of the Cf value, the target utilization factor Uftag, and the maximum power generation amount Wmax may be determined in advance for each combination of gas composition and fluctuation range, and one of the combinations of the set values ​​may be set based on the combination of gas composition and fluctuation range.

[0051] In the above-described embodiment, the setting values ​​are set by an operator in the setting method of FIG. 3 . However, this is not limiting and the control device 100 may set the setting values. For example, the control device 100 may store gas-related information for each installation area and information on setting values ​​corresponding to the gas-related information in a storage unit such as the EEPROM 104. Upon acquiring information on the installation area, the control device 100 may read and set the setting values ​​corresponding to the installation area from the storage unit. Alternatively, the control device 100 may access a data server that stores gas-related information for each installation area and information on setting values ​​corresponding to the gas-related information via communication over a network, and read and set the setting values ​​corresponding to the installation area. Alternatively, application software having the setting method function may be installed in the worker's mobile device, and the worker may execute the application software on the mobile device to obtain the setting values ​​and register them in the control device 100. Alternatively, the setting values ​​obtained by executing the application software may be transmitted from the mobile device to the control device 100, and the control device 100 may register the received setting values.

[0052] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be described below. In the embodiment, the fuel cell stack 21 corresponds to the "fuel cell" of the present disclosure, the reformer 23 corresponds to the "reforming section," the raw fuel gas supply device 30 corresponds to the "raw fuel gas supply device," the gas flow sensor 39 corresponds to the "flow sensor," and the control device 100 (CPU 101) corresponds to the "controller."

[0053] This specification also discloses the technical idea of ​​changing the original claim 4 of the application from "a method for setting up a fuel cell system as described in claim 1 or 2" to "a method for setting up a fuel cell system as described in any one of claims 1 to 3."

[0054] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0055] The present disclosure is applicable to the fuel cell system manufacturing industry and the like. [Explanation of symbols]

[0056] 10 fuel cell system, 21 fuel cell stack, 23 reformer (reforming section), 30 raw fuel gas supply device, 31 raw fuel gas supply pipe (raw fuel gas supply path), 36 gas pump, 39 gas flow sensor, 100 control device (control section).

Claims

1. a fuel cell stack that generates electricity based on the anode gas and the cathode gas; a reforming unit that reforms a raw fuel gas to generate the anode gas; a raw fuel gas supply device that supplies the raw fuel gas to the reforming unit through a raw fuel gas supply path by driving a gas pump; a flow rate sensor capable of detecting a flow rate of the raw fuel gas in the raw fuel gas supply path, the detected value of which changes depending on the gas composition of the raw fuel gas; a control unit that sets a target current for the fuel cell stack, sets a target fuel flow rate based on the target current so that the fuel utilization rate of the fuel cell stack becomes the target utilization rate, and controls the gas pump so that the fuel flow rate based on the detection value of the flow rate sensor becomes the target fuel flow rate; A method for setting up a fuel cell system comprising: acquiring gas-related information including a fluctuation range of the gas composition of the raw fuel gas in an installation area of ​​the fuel cell system, and setting at least the target utilization rate based on the gas-related information; How to configure a fuel cell system.

2. The target utilization rate is set to be smaller as the fluctuation range of the gas composition in the gas-related information becomes larger. The method for setting a fuel cell system according to claim 1 .

3. the control unit sets the target current within a range of a maximum power generation amount, The larger the fluctuation range of the gas composition in the gas-related information, the smaller the maximum power generation amount is set.

3. The method for setting a fuel cell system according to claim 1.

4. setting a conversion factor for correcting the detection value of the flow sensor based on the gas composition in the gas-related information; 3. The method for setting a fuel cell system according to claim 1.

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