Fuel cell device and control method therefor

Abstract

This fuel cell device comprises a reformer, a fuel cell, and a control device. The control device acquires a first value obtained by detecting a supply amount of each of raw materials. The control device calculates a first ratio and a second ratio on the basis of the respective first values. When at least one of the first ratio and the second ratio is outside an acceptable range determined for each of the ratios, if the difference between a second value and the first value is greater than or equal to a threshold value, the control device changes a setting value for the relevant raw material to the first value and changes a setting value for the other raw material of the two raw materials.

Description

Fuel cell device and control method thereof CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to Japanese Patent Application No. 2022-212545, filed on December 28, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to a fuel cell device and a control method thereof.

[0003] A fuel cell module is known that includes a reformer that uses a raw fuel and steam to cause a reforming reaction, and a fuel cell that generates electricity using the fuel gas reformed in the reformer together with air. For power generation by the fuel cell module, an appropriate S / C (Steam Carbon Ratio) and A / F (Air Per Fuel) are calculated in advance from the viewpoint of operational efficiency, etc. Furthermore, in the fuel cell module, set values ​​are set for the supply amounts of each raw material, such as the raw fuel, steam, and air, and the fuel is controlled to be supplied to the fuel cell module at the set values ​​(see Patent Document 1).

[0004] JP 2010-212141 A

[0005] A control device according to a first aspect is a fuel cell device comprising: a reformer that produces fuel by reforming a raw fuel and steam; a fuel cell that generates electricity using the fuel and air; and a control device that maintains the amounts of raw materials, including the fuel, the air, the raw fuel, and the steam, supplied to the fuel cell and the reformer at set values, wherein the control device: acquires first values ​​that detect the amounts of the raw materials supplied; calculates a first ratio, which is the ratio of the number of moles of steam to the number of moles of carbon in the raw fuel, and a second ratio, which is the ratio of the amount of fuel supplied to the air, based on the first values; and when at least one of the first ratio and the second ratio is outside the allowable ranges set for each of the first ratio and the second ratio, if the difference between a second value set as a set value for one of the two raw materials for which the one is to be calculated and the first value for the raw material is equal to or greater than a threshold value, changes the set value for the raw material to the first value, and changes the set value for the other of the two raw materials.

[0006] A control method according to a second aspect is a control method for a fuel cell device comprising a reformer that produces fuel by reforming using raw fuel and steam, and a fuel cell that generates electricity using the fuel and air, and is controlled to maintain the amounts of raw materials, including the fuel, the air, the raw fuel, and the steam, supplied to the reformer and the fuel cell at set values, the control method comprising: obtaining first values ​​that detect the amounts of the raw materials supplied; calculating a first ratio, which is the ratio of the number of moles of steam to the number of moles of carbon in the raw fuel supplied to the reformer, and a second ratio, which is the ratio of the amount of fuel supplied to the air, based on the first values; and when at least one of the first ratio and the second ratio falls outside the allowable ranges set for each of the first ratio and the second ratio, if the difference between a second value set as a set value for one of the two raw materials for which the one is to be calculated and the first value for the raw material is equal to or greater than a threshold value, changing the set value for the raw material to the first value, and changing the set value for the other of the two raw materials.

[0007] It is a configuration diagram showing a schematic configuration of a fuel cell device according to the present embodiment. It is a flowchart for explaining a first allowable range maintenance process executed by the control unit of Fig. 1. It is a flowchart for explaining a second allowable range maintenance process executed by the control unit of Fig. 1. It is a flowchart for explaining a third allowable range maintenance process executed by the control unit of Fig. 1.

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same components are denoted by the same reference numerals.

[0009] 1 , a fuel cell device 10 according to an embodiment of the present disclosure includes a fuel cell module 26 and a control device 13. The fuel cell device 10 may further include a first flow meter 14, a second flow meter 15, a third flow meter 16, a detection mechanism 17, a first adjustment mechanism 18, a second adjustment mechanism 19, a third adjustment mechanism 20, and a memory unit 21.

[0010] The fuel cell module 26 includes a reformer 11 and a fuel cell 12. The fuel cell module 26 may further include a combustion section 22.

[0011] The reformer 11 generates fuel by steam reforming using a raw fuel and steam. The raw fuel is a light hydrocarbon such as methane, ethane, propane, or butane. The steam may be supplied to the reformer 11 as liquid reforming water and vaporized into steam in a vaporization unit provided in the reformer 11. The fuel includes, for example, hydrogen. In this specification, the raw fuel and steam are also referred to as "feedstock."

[0012] The fuel cell 12 may be configured to include a plurality of fuel cell units. The fuel cell units may be solid oxide fuel cell units. The fuel cell units generate electricity through an electrochemical reaction between the fuel produced by the reformer 11 and an oxidant such as oxygen contained in the air. In this specification, the fuel and air are also referred to as "raw materials." Unreacted fuel and unreacted oxidant discharged from the fuel cell units may be combusted in the combustion section 22 to provide energy for the steam reforming reaction in the reformer 11. Water discharged from the fuel cell units may be discharged from the fuel cell 12 as water vapor together with exhaust gas resulting from the combustion of the unreacted fuel and unreacted oxidant.

[0013] The first flow meter 14 may be provided in a first supply path 23 that supplies raw fuel to the reformer 11. The first flow meter 14 may detect the supply amount of raw fuel supplied to the reformer 11. The second flow meter 15 may be provided in a second supply path 24 that supplies water to the reformer 11. The second flow meter 15 may detect the supply amount of reforming water supplied to the reformer 11. The third flow meter 16 may be provided in a third supply path 25 that supplies air to the fuel cell 12. The third flow meter 16 may detect the supply amount of air supplied to the fuel cell 12. The supply amounts detected by the first flow meter 14, the second flow meter 15, and the third flow meter 16 are flow rates, in other words, supply amounts per hour. Furthermore, instead of the second flow meter 15, the supply amount of reforming water may be detected based on the driving status of a pump that supplies the reforming water. Specifically, in a configuration in which a pump capable of outputting specifications such as discharge volume and rotation speed is used, the supply volume of reforming water may be detected by calculation based on the output specifications. Alternatively, in a configuration in which a pump driven by a pulse motor is used, the discharge volume of the pump may be detected by calculation as the supply volume of reforming water based on the drive duty ratio of the pulse motor.

[0014] The detection mechanism 17 detects the A / F, which is the ratio of the amount of air supplied to the fuel cell 12 to the amount of fuel supplied, from the amount of fuel supplied detected by the first flow meter 14 and the amount of air supplied detected by the third flow meter 16.

[0015] The first adjustment mechanism 18 may adjust the supply amount of the raw fuel to a set value set by the control device 13. The first adjustment mechanism 18 may be, for example, a pump whose duty ratio is changeable.

[0016] The second adjusting mechanism 19 may adjust the amount of water supplied to a set value set by the control device 13. The second adjusting mechanism 19 may be, for example, a pump whose duty ratio is changeable.

[0017] The third adjustment mechanism 20 may adjust the amount of air supplied to a set value set by the control device 13. The third adjustment mechanism 20 may be, for example, a blower with a variable duty ratio.

[0018] The storage unit 21 includes any of semiconductor memory, magnetic memory, and optical memory. The semiconductor memory is, for example, RAM (Random Access Memory), ROM (Read Only Memory), etc. The RAM is, for example, SRAM (Static Random Access Memory), DRAM (Dynamic Random Access Memory), etc. The ROM is, for example, EEPROM (Electrically Erasable Programmable Read Only Memory), etc. The storage unit 21 may function as a main storage device, an auxiliary storage device, or a cache memory. The storage unit 21 stores data used in the operation of the fuel cell device 10 and data obtained by the operation of the fuel cell device 10. For example, the storage unit 21 stores system programs, application programs, embedded software, and the like.

[0019] The control device 13 includes at least one processor, at least one dedicated circuit, or a combination thereof. The processor may be a general-purpose processor such as a central processing unit (CPU) or a graphics processing unit (GPU), or a dedicated processor specialized for a specific process. The dedicated circuit may be, for example, a field-programmable gate array (FPGA) or an application-specific integrated circuit (ASIC).

[0020] The control device 13 maintains the feed rates of the raw materials to the reformer 11 and the fuel cell 12 at set values. More specifically, the control device 13 may determine the set values ​​of the feed rates of each raw material. In this specification, the values ​​applied to the set values ​​of the feed rates of each raw material may also be referred to as second values.

[0021] Next, the control device 13 provides the determined set values ​​as information to the first adjustment mechanism 18, the second adjustment mechanism 19, and the third adjustment mechanism 20. By providing the set values, the control device 13 causes the first adjustment mechanism 18, the second adjustment mechanism 19, and the third adjustment mechanism 20 to maintain the amounts of raw material supplied to the reformer 11 and the fuel cell 12 at the set values.

[0022] Note that the fuel supplied to the fuel cell 12 is produced in the reformer 11, and therefore the amount of fuel supplied to the fuel cell 12 is indirectly adjusted by adjusting the amount of raw fuel supplied to the reformer 11. Therefore, the amount of fuel supplied to the fuel cell 12 corresponds to the amount of raw fuel supplied to the reformer 11, and the second value for the fuel corresponds to the second value for the raw fuel.

[0023] The control device 13 may use a predetermined algorithm to determine the set values ​​for the supply amounts of each raw material. For example, the control device 13 may use an algorithm to determine the supply amounts of raw fuel and steam to the reformer 11 so that a first ratio in the reformer 11 matches the set value. The first ratio is S / C, which is the ratio of the number of moles of steam to the number of moles of carbon in the raw fuel supplied to the reformer 11. Alternatively, for example, the control device 13 may use an algorithm to determine the supply amounts of fuel and air to the fuel cell 12 so that a second ratio in the fuel cell 12 matches the set value. The second ratio is A / F, which is the ratio of the amount of air supplied to the fuel cell 12 to the amount of fuel supplied.

[0024] After determining the supply amount of one of the raw fuel and steam, the control device 13 may determine the supply amount of the other based on the S / C.

[0025] Since S / C is a molar ratio, the control device 13 may acquire the average molecular weight and density of the raw fuel to determine the supply amounts (flow rates) of the raw fuel and steam based on the S / C. The control device 13 may acquire the average molecular weight calculated based on the component analysis results of the raw fuel gas obtained in advance. Alternatively, the control device 13 may acquire the component analysis results from a gas detection device that performs component analysis of the supplied raw fuel, and acquire the average molecular weight based on the component analysis results. The control device 13 may acquire density information from a density sensor that detects the density of the supplied raw fuel. The control device 13 may store the components and densities of the raw fuels that can be used in advance and call them up from the memory according to the type of raw fuel set at the time of installation.

[0026] The control device 13 may calculate the relationship between the flow rate of the raw fuel and the flow rate of the steam based on the average molecular weight and density of the raw fuel and the known molecular weight of water. The control device 13 may use this relationship to determine the set values ​​of the supply amounts of the raw fuel and the steam. As described above, since the raw fuel is supplied to the reformer 11 in the form of water, the control device 13 may determine the set value of the flow rate of water instead of the flow rate of the steam.

[0027] After determining the supply amount of one of fuel and air, the control device 13 may determine the supply amount of the other based on the A / F.

[0028] The power generation of the fuel cell 12 may be adjustable. The control device 13 may determine the set value of each raw material to a value that has a predetermined correspondence relationship with the set value of the power generation according to the power required by the user. The set value of the power generation may vary according to the required power. In order to determine the set value of each raw material according to the set value of the power generation, a correspondence table or a relational expression that shows a predetermined correspondence relationship between the set value of the power generation and the supply amount of each raw material may be stored in the memory unit 21. The supply amount of each raw material may have a proportional relationship with the set value of the power generation.

[0029] The S / C and A / F calculated using the supply amounts of the respective raw materials associated with the set value of the generated power may match the set values ​​of the S / C and A / F described above.

[0030] The control device 13 acquires a first value detected as the supply amount of each raw material. The first value does not mean the same value for all raw materials, but may be different for each raw material. Specifically, the control device 13 acquires the supply amount detected by the first flow meter 14 as the first value of the raw fuel. The control device 13 also acquires the supply amount detected by the second flow meter 15 as the first value of water. The control device 13 also acquires the supply amount detected by the third flow meter 16 as the first value of air.

[0031] The control device 13 calculates a first ratio and a second ratio based on the first values ​​of the respective ingredients. The control device 13 determines whether the first ratio is outside a predetermined allowable range for the first ratio. The control device 13 also determines whether the second ratio is outside a predetermined allowable range for the second ratio.

[0032] The allowable range of the first ratio may be determined from various perspectives. As described below, whether the first ratio is too high or too low increases the possibility of carbon monoxide generation. Therefore, the allowable range of the first ratio is determined, for example, to be a range that allows the amount of carbon monoxide generated during combustion in the combustion unit 22 to be suppressed to an allowable amount.

[0033] If the first ratio is too low, the amount of heat absorbed by the vaporization of water decreases, causing the temperature of the reformer 11 to rise. If the amount of water supplied is increased while the temperature of the reformer 11 is high, the likelihood of bumping occurring within the reformer 11 increases. This can cause fluctuations in the amount of fuel produced in the reformer 11, which can result in fluctuations in the second ratio. Fluctuations in the second ratio increase the likelihood of the second ratio falling outside its allowable range, and as will be described later, increase the likelihood of carbon monoxide being generated during combustion in the combustion section 22.

[0034] On the other hand, if the first ratio is too large, the fuel generated in the reformer 11 and unreacted in the fuel cell 12 is less likely to undergo diffusion combustion in the combustion section 22. As a result, incomplete combustion occurs in the combustion section 22, increasing the possibility of carbon monoxide generation. Furthermore, if the first ratio is too large, the amount of steam increases, increasing the specific heat of the entire mixed gas of the unreacted fuel and oxidizer sent to the combustion section 22 and the unreacted steam in the reformer 11. The increase in specific heat also reduces the temperature of the mixed gas, increasing the possibility of incomplete combustion.

[0035] The allowable range of the second ratio may be determined from various perspectives. As described below, whether the second ratio is too high or too low increases the possibility of carbon monoxide generation. Therefore, the allowable range of the second ratio is determined, for example, to be a range that allows the amount of carbon monoxide generated during combustion in the combustion section 22 to be suppressed to an allowable amount.

[0036] The combustible gas and oxidizer used for combustion in the combustion section 22 are the fuel and air that were unreacted in the fuel cell 12. Therefore, if the first ratio is too large, there is a high possibility that the amount of combustible gas in the combustion section 22 will be too small compared to the amount of oxidizer. This increases the possibility of misfire in the combustion section 22, and therefore the possibility of carbon monoxide generation.

[0037] On the other hand, if the first ratio becomes too small, the combustible gas in the combustion section 22 is more likely to be excessively large compared to the oxidizer, which increases the possibility of carbon monoxide being generated in the combustion section 22 and also increases the possibility of carbon monoxide being generated due to incomplete combustion.

[0038] When at least one of the first ratio and the second ratio is outside the allowable range defined for each, the control device 13 selects the ratio that is outside the allowable range. The control device 13 determines whether the difference between a second value defined as a set value for each of the two feedstocks for which the selected ratio is calculated and the first value for each of the two feedstocks is equal to or greater than a threshold. The two feedstocks are steam and raw fuel in the first ratio. The two feedstocks are air and fuel in the second ratio.

[0039] For one ingredient for which the difference between the first value and the second value is equal to or greater than a threshold, the control device 13 changes the set value for that ingredient to the first value. The control device 13 also changes the set value for the other ingredient. The threshold for a given ingredient is, for example, an adjustment error by the first adjustment mechanism 18, the second adjustment mechanism 19, or the third adjustment mechanism 20. Generally, the threshold is narrower than the allowable range, and when one of the first ratio and the second ratio is outside the allowable range, the difference between the first value and the second value of at least one of the two ingredients used to calculate that ratio is equal to or greater than the threshold.

[0040] The control device 13 may change the set value for the raw material corresponding to the first value to the first value when the difference between the first value and the second value is equal to or greater than a threshold value and the first value is smaller than the second value. For example, the control device 13 changes the set value for the raw material to the first value when the first ratio is outside the allowable range and the difference obtained by subtracting the first value from the second value of the raw material is equal to or greater than a threshold value. On the other hand, the control device 13 maintains the set value for the raw material at the second value even when the first ratio is outside the allowable range and the difference obtained by subtracting the second value from the first value of the raw material is equal to or greater than the threshold value.

[0041] The control device 13 may change the set value of one ingredient for which the set value has been changed to the first value to a value based on the set value set for the first value and the selected ratio (the first ratio or the second ratio). The set value may be set to any value within the above-mentioned allowable range.

[0042] For example, when the first ratio is outside the allowable range and the set value of the raw fuel is changed to the first value, the control device 13 calculates the number of moles of carbon in the raw fuel corresponding to the first value. The control device 13 calculates the number of moles of steam to be supplied to the reformer 11 by multiplying the set value set for the first ratio by the number of moles of carbon in the raw fuel corresponding to the first value. The control device 13 converts the calculated number of moles of steam into a supply amount of steam. The control device 13 changes the set value of the steam to the converted value.

[0043] In a configuration in which the control device 13 determines the set value of each raw material according to the set value of the power generation corresponding to the user's power request, the control device 13 may change the set value of one raw material that satisfies the above-mentioned condition to a first value, and then change the set value of the power generation. Specifically, the control device 13 may calculate a fourth value by multiplying a third value set for the set value of the power generation by a coefficient obtained by dividing the first value of the raw material by the second value. Next, the control device 13 may change the set value of the power generation from the third value to a fourth value. Next, the control device 13 may change the set values ​​of other raw materials, including the other raw material relative to the one raw material, to values ​​determined in accordance with the above-mentioned predetermined correspondence relationship and the fourth value. Therefore, the S / C and A / F calculated by the control device 13 using the set values ​​of each raw material determined in accordance with the set value of the power generation may match the set values ​​of the S / C and A / F.

[0044] After changing the set value of the power generation to the fourth value, the control device 13 may obtain new first values ​​that detect the supply amounts of each raw material. The control device 13 may calculate the difference between the new first value of each raw material and the value that is determined as the set value for that raw material, in other words, the first value when the set value of the power generation is the third value. If the difference is equal to or greater than a threshold value, the control device 13 may shut down the fuel cell device 10.

[0045] Alternatively, the control device 13 may return the set value of the power generation to the third value after a predetermined time has elapsed since the set value of the power generation was changed to the fourth value. After returning the set value of the power generation to the third value, the control device 13 may obtain first values ​​obtained by detecting the supply amounts of each of the raw materials. The control device 13 may calculate the first ratio and the second ratio based on the first values.

[0046] If at least one of the calculated first ratio and second ratio is outside the allowable range, the control device 13 may set the upper limit of the power generation to a third value, and may change the power generation to be equal to or less than the upper limit in subsequent operations of the fuel cell device 10.

[0047] Alternatively, if at least one of the calculated first ratio and second ratio is outside the allowable range, the control device 13 may shut down the fuel cell device 10. Before shutting down the fuel cell device 10, the control device 13 may perform the steps of changing the set value of the power generation power to the fourth value, waiting a predetermined time, changing it to the third value, and determining whether the first ratio and the second ratio are outside the allowable range at least once more, and then shut down the fuel cell device 10.

[0048] Next, the first allowable range maintenance process executed by the control device 13 in this embodiment will be described with reference to the flowchart of Fig. 2. The first allowable range maintenance process is started, for example, periodically or cyclically.

[0049] In step S100, the control device 13 acquires, as first values, the supply amounts of the raw fuel, water, and air from the first flow meter 14, the second flow meter 15, and the third flow meter 16. After acquisition, the process proceeds to step S101.

[0050] In step S101, the control device 13 calculates the S / C and A / F based on the first values ​​of the respective raw materials acquired in step S100. After the calculation, the process proceeds to step S102.

[0051] In step S102, the control device 13 determines whether at least one of the S / C and A / F calculated in step S101 is outside the allowable ranges set for the S / C and A / F, respectively. If not, the first allowable range maintenance process ends. If outside the allowable range, the process proceeds to step S103.

[0052] In step S103, the control device 13 calculates the difference between the second value set as the set value for each ingredient and the first value acquired in step S100. After the calculation, the process proceeds to step S104.

[0053] In step S104, the control device 13 selects one of the ingredients whose difference is equal to or greater than the threshold value in step S103. After the selection, the process proceeds to step S105.

[0054] In step S105, the control device 13 determines whether the second value of the ingredient selected in step S104 is greater than the first value. If the second value is not greater than the first value, the first tolerance range maintenance process ends. If the second value is greater than the first value, the process proceeds to step S106.

[0055] In step S106, the control device 13 changes the set value of the ingredient selected in step S104 to the first value acquired in step S100. After the change, the process proceeds to step S107.

[0056] In step S107, the control device 13 changes the set value of the generated power based on the first and second values ​​of the raw material selected in step S104. After the change, the process proceeds to step S108.

[0057] In step S108, the control device 13 changes the set values ​​of the raw materials other than the raw material selected in step S104, in accordance with the set value of the power generation changed in step S107. After the changes, the process proceeds to step S109.

[0058] In step S109, the control device 13 again acquires the supply amounts of the raw fuel, water, and air as first values ​​from the first flow meter 14, the second flow meter 15, and the third flow meter 16. After acquisition, the process proceeds to step S110.

[0059] In step S110, the control device 13 calculates the difference between the new first value obtained in step S109 and the first value obtained in step S100. After the calculation, the process proceeds to step S111.

[0060] In step S111, the control device 13 determines whether the difference calculated in step S110 is equal to or greater than a threshold value. If the difference is not equal to or greater than the threshold value, the first tolerance range maintenance process ends. If the difference is equal to or greater than the threshold value, the process proceeds to step S112.

[0061] In step S112, the control device 13 shuts down the fuel cell device 10. After shutting down, the first allowable range maintenance process ends.

[0062] Next, the second allowable range maintenance process executed by the control device 13 in this embodiment will be described with reference to the flowchart of Fig. 3. The second allowable range maintenance process is started, for example, periodically or cyclically.

[0063] From step S200 to step S208, the control device 13 executes the same processes as steps S100 to S108 of the first allowable range maintenance process. After changing the set values ​​of each ingredient in step S208, the process proceeds to step S209.

[0064] In step S209, the control device 13 waits for a predetermined time period. After waiting for the predetermined time period, the process proceeds to step S210.

[0065] In step S210, the control device 13 returns the set value of the generated power to the fourth value. After returning the set value, the process proceeds to step S211.

[0066] In step S211, the control device 13 again acquires the supply amounts of the raw fuel, water, and air as first values ​​from the first flow meter 14, the second flow meter 15, and the third flow meter 16. After acquisition, the process proceeds to step S212.

[0067] In step S212, the control device 13 calculates the S / C and A / F based on the first values ​​of the respective raw materials acquired in step S211. After the calculation, the process proceeds to step S213.

[0068] In step S213, the control device 13 determines whether at least one of the S / C and A / F calculated in step S212 is outside the allowable ranges set for the S / C and A / F, respectively. If not, the second allowable range maintenance process ends. If outside the allowable ranges, the process proceeds to step S214.

[0069] In step S214, the control device 13 sets the set value of the generated power to the third value, and then the second allowable range maintenance process ends.

[0070] Next, the third allowable range maintenance process executed by the control device 13 in this embodiment will be described with reference to the flowchart of Fig. 4. The third allowable range maintenance process is started, for example, periodically or cyclically.

[0071] In steps S300 to S313, the control device 13 executes the same processes as in steps S200 to S213 of the second allowable range maintenance process. In step S313, if at least one of the S / C and the A / F is outside the allowable ranges set for the S / C and the A / F, the process proceeds to step S314.

[0072] In step S314, the control device 13 shuts down the fuel cell device 10. After shutting down, the third allowable range maintenance process ends.

[0073] The fuel cell device 10 of this embodiment, configured as described above, includes a reformer 11 that generates fuel by reforming raw fuel and steam, a fuel cell 12 that generates electricity using the fuel and air, and a control device 13 that maintains the supply amounts of raw materials, including fuel, air, raw fuel, and steam, to the reformer 11 and the fuel cell 12 at set values. The control device 13 acquires first values ​​that detect the supply amounts of each raw material and calculates a first ratio and a second ratio based on the respective first values. If at least one of the first ratio and the second ratio falls outside a predetermined allowable range, the control device 13 changes the set value for one of the two raw materials for which the first ratio and the second ratio are calculated to the first value when the difference between the second value set for that raw material and the first value for that raw material is equal to or greater than a threshold value. As described above, if the S / C and A / F ratios fall outside the allowable ranges, the amount of carbon monoxide generated increases. While the generated carbon monoxide can be combusted using a combustion catalyst, it is desirable to reduce the amount of carbon monoxide generated. Under normal circumstances, set values ​​for the flow rates of the raw fuel, water, and air are determined and controlled to maintain the first ratio (S / C) and the second ratio (A / F) within the allowable ranges. However, due to malfunctions of the first adjustment mechanism 18, the second adjustment mechanism 19, and the third adjustment mechanism 20, it may become difficult to adjust either the water or the raw fuel, or either the fuel or the air, to the set values. In such a situation, it may become difficult to maintain the S / C and A / F within the allowable ranges even with normal control. On the other hand, the fuel cell device 10 having the above-described configuration determines that the difference between the detected first value and the set second value is equal to or greater than a threshold value, and can change the set value of a raw material whose supply rate is difficult to maintain at the set value to a maintainable value. Furthermore, the control device 13 can also change the set value of the other raw material used in calculating the S / C or A / F for that raw material. Therefore, the fuel cell device 10 can maintain the S / C and A / F within the allowable ranges even when it is difficult to maintain the supply rate of a given raw material at its original set value.

[0074] Furthermore, in the fuel cell system 10, the control device 13 changes the set value for one of the feedstocks to a first value when the difference between the first and second values ​​for that feedstock is equal to or greater than a threshold value and the first value is smaller than the second value. The fuel cell system 10 is typically assumed to be operating at rated capacity. Therefore, for a feedstock whose supply rate is difficult to maintain at its set value, it may be difficult to maintain the other feedstock at an increased set value in the S / C or A / F calculation. In such an event, the control device 13 adds the condition for changing the set value that the detected first value is the second value, which is the set value, thereby limiting the situation to one in which it is easier to keep the S / C and A / F within the allowable range. Therefore, the fuel cell system 10 increases the likelihood that the effect of keeping the S / C and A / F within the allowable range will be realized.

[0075] Furthermore, in the fuel cell system 10, the control device 13 changes the set value for the other raw material to a value based on the first value and the set value set as the ratio of one of the raw materials that is outside the allowable range. With this configuration, the fuel cell system 10 further increases the possibility of keeping the S / C and A / F within the allowable range.

[0076] In addition, in the fuel cell system 10, the control device 13 determines the set values ​​of each raw material to a value that has a predetermined correspondence relationship with the set value of the required power generation, changes the set value for one of the two raw materials to a first value, and then changes the set value for the other raw material from a third value set for the power generation to a fourth value calculated by multiplying the third value by a coefficient obtained by dividing the first value by the second value. The control device 13 then changes the set value for the other raw material based on the fourth value and the predetermined correspondence. Changing the supply amount of raw fuel and the supply amount of fuel corresponding to the supply amount of raw fuel changes the power generation of the fuel cell 12. Changing the supply amount of air or water to keep the S / C and A / F within the allowable ranges also changes the supply amount of raw fuel. In response to such an event, in the fuel cell system 10, the control device 13 calculates the power generation amount corresponding to the available supply amount of the raw material whose supply amount is difficult to maintain at the set value, and changes the set values ​​of the other raw materials according to the calculated power generation amount. Therefore, the fuel cell device 10 can easily calculate the set values ​​for raw materials other than those for which it is difficult to maintain the supply amount at the set value, using the relationship between the generated power that can be used during normal operation and the set values ​​for the supply amount of each raw material.

[0077] Furthermore, in the fuel cell system 10, the control device 13 calculates the first ratio and the second ratio using the set value of the raw material determined according to the set value of the power generation, so that the first ratio and the second ratio match the set values ​​for the first ratio and the second ratio. With this configuration, the fuel cell system 10 further increases the possibility of keeping the S / C and A / F within the allowable range.

[0078] Furthermore, in the fuel cell device 10, the control device 13 returns the set value of the power generation to the third value after a predetermined time has elapsed since the set value of the power generation was changed to the fourth value. Changing the set value of the power generation can cause a surplus or shortage of power generation. Therefore, the fuel cell device 10 can try to bring the power generation closer to the original set value again after changing the set value of the power generation to keep the S / C and A / F within the allowable range.

[0079] Furthermore, in the fuel cell device 10, the control device 13, after returning the set value of the power generation to the third value, acquires first values ​​detected by detecting the supply amounts of each raw material, calculates the first ratio and the second ratio based on the respective first values, and sets the upper limit of the power generation to the third value if at least one of the first ratio and the second ratio is outside the allowable range. With this configuration, the fuel cell device 10 can perform a test to bring the power generation closer to the original set value and determine whether it is possible to return to normal operation. Furthermore, the fuel cell device 10 can provide operating conditions that keep the S / C and A / F within allowable ranges based on the determination result.

[0080] Furthermore, in the fuel cell device 10, the control device 13 returns the set value of the power generation to the third value, acquires first values ​​detected by the supply amounts of each raw material, calculates the first ratio and the second ratio based on the respective first values, and stops operation if at least one of the first ratio and the second ratio is outside the allowable range. Frequent changes in the set values ​​of the power generation and each raw material are undesirable from the perspective of stable operation. Therefore, the fuel cell device 10 having the above configuration can avoid continued unstable operation by stopping operation.

[0081] Furthermore, in the fuel cell device 10, after the set value of the power generation is changed to the fourth value, the control device 13 acquires new first values ​​that detect the supply amounts of each raw material, and shuts down the fuel cell device 10 if the difference between the new first value of each raw material and the set value for that raw material is equal to or greater than a threshold. If the supply amounts of raw materials cannot be maintained even after the set values ​​are changed to values ​​that were considered to be maintainable, this may be due to a malfunction of at least one of the first flow meter 14, the second flow meter 15, the third flow meter, the detection mechanism 17, the first adjustment mechanism 18, the second adjustment mechanism 19, and the third adjustment mechanism 20, a communication error between these devices and the control device 13, or blockages in the first supply path 23, the second supply path 24, and the third supply path 25. In the event of such an event, the fuel cell device 10 having the above-described configuration may determine that a malfunction has occurred and shut down operation.

[0082] In one embodiment, (1) a fuel cell device includes: a reformer that generates fuel by reforming a raw fuel and steam; a fuel cell that generates electricity using the fuel and air; and a control device that maintains the supply amounts of raw materials including the fuel, the air, the raw fuel, and the steam to the fuel cell and the reformer at set values, wherein the control device: acquires first values ​​that detect the supply amounts of each of the raw materials; calculates a first ratio, which is the ratio of the number of moles of steam to the number of moles of carbon in the raw fuel, and a second ratio, which is the ratio of the supply amount of fuel to the air, based on each of the first values; and when at least one of the first ratio and the second ratio is outside the allowable ranges set for each of the two raw materials for which the one is to be calculated, if the difference between a second value set as a set value for one of the raw materials and the first value for the raw material is equal to or greater than a threshold value, changes the set value for the raw material to the first value, and changes the set value for the other of the two raw materials.

[0083] (2) In the fuel cell device of (1) above, when the difference between the first value and the second value of one of the raw materials is equal to or greater than a threshold value and the first value is smaller than the second value, the control device changes the set value for the raw material to the first value.

[0084] (3) In the fuel cell device of (1) or (2) above, the control device changes the set value for the other raw material to a value based on the first value and a set value set as a ratio of one of the raw materials that is outside the allowable range.

[0085] (4) In the fuel cell device of (1) or (2) above, the control device determines the set value of each of the raw materials in the fuel cell module to a value that has a predetermined correspondence with the set value of the required power generation, changes the set value for one of the two raw materials to the first value, and then changes the set value for the one of the two raw materials from a third value set in the set value of the power generation to a fourth value calculated by multiplying the third value by a coefficient obtained by dividing the first value by the second value, and changes the set value for the other raw material based on the fourth value and the predetermined correspondence.

[0086] (5) In the fuel cell device of (4) above, the first ratio and the second ratio calculated using the set value of the raw material determined according to the set value of the power generation coincide with the set values ​​for the first ratio and the second ratio.

[0087] (6) In the fuel cell device of (4) or (5) above, the control device returns the set value of the generated power to the third value after a predetermined time has elapsed since the set value was changed to the fourth value.

[0088] (7) In the fuel cell device of (6) above, the control device returns the set value of the power generation power to the third value, then acquires first values ​​that detect the supply amounts of each of the raw materials, calculates the first ratio and the second ratio based on the respective first values, and if at least one of the first ratio and the second ratio is outside the allowable range, sets the upper limit value of the power generation power to the third value.

[0089] (8) In the fuel cell device of (6) above, after returning the set value of the power generation power to the third value, the control device acquires first values ​​that detect the supply amounts of each of the raw materials, calculates the first ratio and the second ratio based on the respective first values, and stops the fuel cell module if at least one of the first ratio and the second ratio is outside the allowable range.

[0090] (9) In the fuel cell device of (6) above, after changing the set value of the power generation power to the fourth value, the control device acquires a new first value that detects the supply amount of each of the raw materials, and if the difference between the new first value of each of the raw materials and the value determined as the set value for each of the raw materials is equal to or greater than the threshold value, the control device stops the fuel cell module.

[0091] In one embodiment, (10) a control method is a control method for a fuel cell device comprising: a reformer that produces fuel by reforming a raw fuel and steam; and a fuel cell that generates electricity using the fuel and air; and the control method is to maintain the supply amounts of raw materials, including the fuel, the air, the raw fuel, and the steam, to the reformer and the fuel cell at set values, the control method comprising: obtaining first values ​​that detect the supply amounts of the raw materials; calculating a first ratio, which is the ratio of the number of moles of steam to the number of moles of carbon in the raw fuel supplied to the reformer, and a second ratio, which is the ratio of the supply amount of fuel to the air, based on the first values; and when at least one of the first ratio and the second ratio is outside the allowable ranges set for each of the first ratio and the second ratio, if the difference between a second value set as a set value for one of the two raw materials for which the one is to be calculated and the first value for the raw material is equal to or greater than a threshold value, changing the set value for the raw material to the first value, and changing the set value for the other of the two raw materials.

[0092] The above has described an embodiment of the fuel cell device 10, but embodiments of the present disclosure can also be embodied as a method or program for implementing the device, as well as a storage medium on which a program is recorded (for example, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a CD-RW, a magnetic tape, a hard disk, or a memory card, etc.).

[0093] Furthermore, the implementation form of the program is not limited to application programs such as object code compiled by a compiler or program code executed by an interpreter, but may also be in the form of a program module incorporated into an operating system. Furthermore, the program may or may not be configured so that all processing is performed solely by the CPU on the control board. The program may also be configured so that part or all of it is executed by another processing unit mounted on an expansion board or expansion unit added to the board as needed.

[0094] The drawings illustrating the embodiments of the present disclosure are schematic, and the dimensional ratios and the like in the drawings do not necessarily correspond to the actual ones.

[0095] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art could make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component can be rearranged so as not to cause logical inconsistencies, and multiple components can be combined or divided into one.

[0096] All of the features described in this disclosure and / or all steps of all of the disclosed methods or processes may be combined in any combination except combinations in which these features are mutually exclusive. Furthermore, each feature described in this disclosure may be replaced by an alternative feature serving the same, equivalent, or similar purpose, unless expressly denied. Thus, unless expressly denied, each disclosed feature is only one example of a generic series of identical or equivalent features.

[0097] Furthermore, embodiments of the present disclosure are not limited to the specific configurations of any of the above-described embodiments, but rather extend to any novel feature or combination thereof described herein, or any novel method or process step or combination thereof described herein.

[0098] In this disclosure, descriptions such as "first" and "second" are identifiers for distinguishing the configuration. In this disclosure, the configurations distinguished by descriptions such as "first" and "second" can have their numbers exchanged. For example, a first flow meter can exchange the identifiers "first" and "second" with a second flow meter. The exchange of identifiers is performed simultaneously. The configurations remain distinguished even after the identifier exchange. Identifiers may be deleted. A configuration from which an identifier has been deleted is distinguished by a symbol. The descriptions of identifiers such as "first" and "second" in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of an identifier with a smaller number.

[0099] REFERENCE SIGNS LIST 10 fuel cell device 11 reformer 12 fuel cell 13 control device 14 first flow meter 15 second flow meter 16 third flow meter 17 detection mechanism 18 first adjustment mechanism 19 second adjustment mechanism 20 third adjustment mechanism 21 memory unit 22 combustion unit 23 first supply path 24 second supply path 25 third supply path 26 fuel cell module

Claims

1. A fuel cell device comprising: a reformer that generates fuel by reforming a raw fuel and steam; a fuel cell that generates electricity using the fuel and air; and a control device that maintains the supply amounts of raw materials, including the fuel, the air, the raw fuel, and the steam, to the fuel cell and the reformer at set values, The control device obtaining a first value obtained by detecting the supply amount of each of the raw materials; calculating a first ratio, which is the ratio of the number of moles of water vapor to the number of moles of carbon in the raw fuel, and a second ratio, which is the ratio of the amount of fuel supplied to the amount of air supplied, based on the first values; When at least one of the first ratio and the second ratio falls outside the tolerance ranges set for each of the two ingredients for which the first ratio is to be calculated, if the difference between a second value set as a set value for one of the ingredients and the first value for the ingredient is equal to or greater than a threshold value, the set value for the ingredient is changed to the first value, and the set value for the other ingredient of the two ingredients is changed. Fuel cell device.

2. The control device changes the set value for the one ingredient to the first value when a difference between the first value and the second value for the one ingredient is equal to or greater than a threshold value and the first value is smaller than the second value.

2. The fuel cell device according to claim 1.

3. The control device changes the set value for the other ingredient to a value based on the set value set as the ratio between the first value and the one ingredient that is outside the allowable range.

3. The fuel cell device according to claim 1 or 2.

4. The control device determining a set value for each of the raw materials to a value that has a predetermined correspondence relationship with the set value of the required power generation; changing the set value for one of the two raw materials to the first value, and then changing the set value for the power generation from a third value defined in the set value for the power generation to a fourth value calculated by multiplying the third value by a coefficient obtained by dividing the first value by the second value; changing the set value of the other ingredient based on the fourth value and the predetermined correspondence relationship; 3. The fuel cell device according to claim 1 or 2.

5. The first ratio and the second ratio calculated using the set value of the raw material determined according to the set value of the power generation coincide with the set values ​​for the first ratio and the second ratio.

5. The fuel cell device according to claim 4.

6. The control device returns the set value of the generated power to the third value after a predetermined time has elapsed since the set value was changed to the fourth value.

5. The fuel cell device according to claim 4.

7. After returning the set value of the power generation to the third value, the control device acquires first values ​​that detect the supply amounts of the respective raw materials, calculates the first ratio and the second ratio based on the respective first values, and sets the upper limit value of the power generation to the third value when at least one of the first ratio and the second ratio is outside the allowable range.

7. The fuel cell device according to claim 6.

8. After returning the set value of the power generation power to the third value, the control device acquires first values ​​that detect the supply amounts of the respective raw materials, calculates the first ratio and the second ratio based on the respective first values, and stops the fuel cell module when at least one of the first ratio and the second ratio is outside the allowable range.

7. The fuel cell device according to claim 6.

9. After changing the set value of the power generation power to the fourth value, the control device acquires new first values ​​that detect the supply amounts of the respective raw materials, and when a difference between the new first values ​​of the respective raw materials and the values ​​determined as set values ​​for the respective raw materials is equal to or greater than the threshold value, the control device stops the fuel cell module.

7. The fuel cell device according to claim 6.

10. A control method for a fuel cell device comprising a reformer that generates fuel by reforming a raw fuel and steam, and a fuel cell that generates electricity using the fuel and air, wherein the amounts of raw materials including the fuel, the air, the raw fuel, and the steam supplied to the reformer and the fuel cell are controlled to be maintained at set values, the method comprising: obtaining a first value obtained by detecting the supply amount of each of the raw materials; calculating a first ratio, which is a ratio of the number of moles of water vapor to the number of moles of carbon in the raw fuel supplied to the reformer, and a second ratio, which is a ratio of a supply amount of fuel to air, based on the first values; When at least one of the first ratio and the second ratio falls outside the tolerance ranges set for each of the two ingredients for which the first ratio is to be calculated, if the difference between a second value set as a set value for one of the ingredients and the first value for the ingredient is equal to or greater than a threshold value, the set value for the ingredient is changed to the first value, and the set value for the other ingredient of the two ingredients is changed. A method for controlling a fuel cell device.