Fuel cell device and its control method

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

Cross-reference to related applications

[0001] This application claims the priority of Japanese Patent Application No. 2022-212545 filed in Japan on December 28, 2022, and incorporates the entire disclosure of the prior application herein for reference.

Technical Field

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

Background Art

[0003] A fuel cell module is known that includes a reformer that causes a reforming reaction using a raw fuel and steam, and a fuel cell that generates electricity using the fuel gas reformed in the reformer together with air. In the power generation of the above fuel cell module, appropriate S / C (Steam Carbon Ratio) and A / F (Air Per Fuel) are calculated in advance from the viewpoint of improving the operating efficiency. Further, in the fuel cell module, set values for the supply amounts of the respective raw materials such as raw fuel, steam, and air are determined, and the fuel cell module is controlled to be supplied with the set values (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] The control device according to the first aspect is a fuel cell device including 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 is A first value is obtained which is the supply amount of each of the aforementioned raw materials. Based on each of the aforementioned first values, a first ratio, which is the ratio of moles of water vapor to moles of carbon in the raw fuel, and a second ratio, which is the ratio of the amount of fuel supplied to air, are calculated. If at least one of the first ratio and the second ratio falls outside the tolerance range set for each, and the difference between the second value, which is set as the setting value for one of the two raw materials used to calculate the first ratio, and the first value for that raw material is greater than or equal to a threshold, the setting value for that raw material is changed to the first value, and the setting value for the other of the two raw materials is changed.

[0006] The control method from the second perspective is: A control method for a fuel cell system comprising a reformer that produces fuel by reforming raw fuel and steam, and a fuel cell that generates electricity using the fuel and air, wherein the amount of raw materials including the fuel, air, raw fuel, and steam supplied to the reformer and the fuel cell is controlled to maintain a set value, A first value is obtained which is the supply amount of each of the aforementioned raw materials. Based on each of the aforementioned first values, a first ratio is calculated, which is the 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 is calculated, which is the ratio of the amount of fuel supplied to air. If at least one of the first ratio and the second ratio falls outside the tolerance range set for each, and the difference between the second value, which is set as the setting value for one of the two raw materials used to calculate the first ratio, and the first value for that raw material is greater than or equal to a threshold, the setting value for that raw material is changed to the first value, and the setting value for the other of the two raw materials is changed. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing the general configuration of the fuel cell system according to this embodiment. [Figure 2]This is a flowchart illustrating the first tolerance range maintenance process performed by the control unit shown in Figure 1. [Figure 3] This is a flowchart illustrating the second tolerance range maintenance process performed by the control unit in Figure 1. [Figure 4] This is a flowchart illustrating the third tolerance range maintenance process performed by the control unit in Figure 1. [Modes for carrying out the invention]

[0008] Embodiments of this disclosure will be described below with reference to the drawings. In the components shown in the following drawings, the same components are denoted by the same reference numerals.

[0009] As shown in Figure 1, a fuel cell device 10 according to one embodiment of the present disclosure comprises a fuel cell module 26 and a control device 13. The fuel cell device 10 may further comprise 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 storage 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 produces fuel by steam reforming using raw fuel and steam. The raw fuel is a light hydrocarbon such as methane, ethane, propane, or butane. Steam is supplied to the reformer 11 as liquid reformed water and may be vaporized into steam in a vaporization section provided in the reformer 11. The fuel includes, for example, hydrogen. In this specification, the raw fuel and steam are also referred to as "raw materials".

[0012] The fuel cell 12 may consist of multiple fuel cell cells. The fuel cell cells may be solid oxide fuel cell cells. The fuel cell cells generate electricity through an electrochemical reaction between the fuel produced by the reformer 11 and an oxidizing agent such as oxygen contained in the air. In this specification, fuel and air are also referred to as "raw materials". Unreacted fuel and unreacted oxidizing agent discharged from the fuel cell may be burned in the combustion section 22 to provide energy to carry out the steam reforming reaction in the reformer 11. Water discharged from the fuel cell may be discharged from the fuel cell 12 as water vapor along with the exhaust gas from the combustion of the unreacted fuel and unreacted oxidizing agent.

[0013] A first flow meter 14 may be installed in a first supply channel 23 that supplies raw fuel to the reformer 11. The first flow meter 14 may detect the amount of raw fuel supplied to the reformer 11. A second flow meter 15 may be installed in a second supply channel 24 that supplies water to the reformer 11. The second flow meter 15 may detect the amount of reformed water supplied to the reformer 11. A third flow meter 16 may be installed in a third supply channel 25 that supplies air to the fuel cell 12. The third flow meter 16 may detect the 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 unit of time. Alternatively, instead of the second flow meter 15, the supply amount of reformed water may be detected based on the operating status of the pump that supplies the reformed water. Specifically, in a configuration where a pump capable of outputting parameters such as discharge rate and rotational speed is used, the amount of reformed water supplied may be calculated and detected based on the output parameters. Alternatively, in a configuration where a pump driven by a pulse motor is used, the amount of water discharged by the pump may be calculated and detected as the amount of reformed water supplied based on the duty cycle of the pulse motor.

[0014] The detection mechanism 17 detects the A / F ratio, which is the ratio of the amount of air supplied to the fuel supply to the fuel cell 12, 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 so as to become a set value set by the control device 13. The first adjustment mechanism 18 may be, for example, a pump capable of changing the duty ratio.

[0016] The second adjustment mechanism 19 may adjust the supply amount of water so as to become a set value set by the control device 13. The second adjustment mechanism 19 may be, for example, a pump capable of changing the duty ratio.

[0017] The third adjustment mechanism 20 may adjust the supply amount of air so as to become a set value set by the control device 13. The third adjustment mechanism 20 may be, for example, a blower capable of changing the duty ratio.

[0018] The storage unit 21 includes any one of a semiconductor memory, a magnetic memory, and an optical memory. The semiconductor memory is, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), etc. The RAM is, for example, a SRAM (Static Random Access Memory), a DRAM (Dynamic Random Access Memory), etc. The ROM is, for example, an 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 for 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 a system program, an application program, embedded software, etc.

[0019] The control device 13 is configured to include at least one processor, at least one dedicated circuit, or a combination thereof. The processor is a general-purpose processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or a dedicated processor specialized for specific processing. The dedicated circuit may be, for example, an FPGA (Field-Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like.

[0020] The control device 13 maintains the supply amounts to the reformer 11 of the raw material and the fuel cell 12 at set values. More specifically, the control device 13 may determine the set values of the supply amounts of each raw material. In the present specification, the value applied to the set value of the supply amount of each raw material may also be referred to as a second value.

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

[0022] Since the fuel supplied to the fuel cell 12 is generated in the reformer 11, the supply amount of fuel to the fuel cell 12 is indirectly adjusted by adjusting the supply amount of the raw fuel to the reformer 11. Therefore, the supply amount of fuel to the fuel cell 12 corresponds to the supply amount of the raw fuel 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 a set value. The first ratio is S / C, which is the ratio of moles of steam to 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 a set value. The second ratio is A / F, which is the ratio of the supply amount of air to the supply amount of fuel to the fuel cell 12.

[0024] The control device 13 may determine the supply amount of either raw fuel or steam, and then determine the supply amount of the other based on the S / C ratio.

[0025] Since S / C is a molar ratio, the control device 13 may obtain the average molecular weight and density of the raw fuel in order to determine the supply amount (flow rate) of raw fuel and steam based on S / C. The control device 13 may obtain 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 obtain the component analysis results from a gas detection device that performs component analysis of the supplied raw fuel and obtain the average molecular weight based on said component analysis results. The control device 13 may obtain the density as 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 raw fuels that can be used in advance and recall them from the store 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 water vapor and the flow rate of raw fuel based on the average molecular weight and density of the raw fuel, as well as the known molecular weight of water. The control device 13 may use this relationship to determine the set values ​​for the supply amounts of raw fuel and water vapor. As mentioned above, the reformer 11 is supplied with water, so the control device 13 may determine the set value for the water flow rate instead of the water vapor flow rate.

[0027] The control device 13 may determine the supply amount of either fuel or air, and then determine the supply amount of the other based on the A / F ratio.

[0028] The power generated by the fuel cell 12 may be adjustable. The control device 13 may determine the set values ​​for each raw material to values ​​that have a predetermined correspondence with the set value of the power generated according to the user's requested power. The set value of the power generated may fluctuate according to the requested power. In order to determine the set values ​​of each raw material according to the set value of the power generated, a correspondence table or relational expression showing a predetermined correspondence between the set value of the power generated and the supply amount of each raw material may be stored in the storage unit 21. The supply amount of each raw material may have a proportional relationship with respect to the set value of the power generated.

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

[0030] The control device 13 acquires a first value obtained by detecting the supply amount of each raw material. This first value does not necessarily mean the same value for all raw materials; it may differ depending on the raw material. Specifically, the control device 13 acquires the supply amount detected by the first flow meter 14 as the first value for the raw fuel. The control device 13 also acquires the supply amount detected by the second flow meter 15 as the first value for water. The control device 13 also acquires the supply amount detected by the third flow meter 16 as the first value for air.

[0031] The control device 13 calculates a first ratio and a second ratio based on the first value of each raw material. The control device 13 determines whether the first ratio is outside the permissible range defined for the first ratio. The control device 13 also determines whether the second ratio is outside the permissible range defined for the second ratio.

[0032] The permissible range for the first ratio may be determined from various perspectives. Both excessive and insufficient values ​​of the first ratio increase the likelihood of carbon monoxide generation, as described below. Therefore, the permissible range for the first ratio is determined, for example, to a range that suppresses the amount of carbon monoxide generated during combustion in the combustion section 22 to an acceptable level.

[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. When the water supply is increased while the temperature of the reformer 11 is high, the likelihood of superheating occurring in the reformer 11 increases. As a result, the amount of fuel produced in the reformer 11 may fluctuate, and consequently, the second ratio may also fluctuate. Fluctuations in the second ratio increase the likelihood of it falling outside the acceptable range, and as will be described later, the likelihood of carbon monoxide generation in the combustion chamber 22 increases.

[0034] On the other hand, if the first ratio is excessive, the fuel generated in the reformer 11 and unreacted in the fuel cell 12 will have difficulty diffusing and burning in the combustion section 22. As a result, incomplete combustion will occur in the combustion section 22, increasing the likelihood of carbon monoxide generation. Furthermore, if the first ratio is excessive, the amount of water vapor will increase, increasing the specific heat of the entire mixed gas of unreacted fuel and oxidizer sent to the combustion section 22 and unreacted water vapor in the reformer 11. The increase in specific heat will lower the temperature of the mixed gas, which also increases the likelihood of incomplete combustion.

[0035] The permissible range for the second ratio may be determined from a variety of perspectives. Both excessive and insufficient second ratios increase the likelihood of carbon monoxide generation, as will be explained below. Therefore, the permissible range for the second ratio is determined, for example, to a range that allows the amount of carbon monoxide generated during combustion in the combustion section 22 to be suppressed to an acceptable level.

[0036] In the combustion section 22, the combustible gas and oxidizer used for combustion are the unreacted fuel and air from the fuel cell 12. Therefore, if the first ratio becomes too large, the amount of combustible gas in the combustion section 22 is likely to be insufficient compared to the oxidizer. As a result, the possibility of misfire in the combustion section 22 increases, and thus the possibility of carbon monoxide generation increases.

[0037] On the other hand, if the first ratio becomes too small, the likelihood of the combustible gas in the combustion section 22 being excessive compared to the oxidizer increases. As a result, the likelihood of carbon monoxide being generated in the combustion section 22 increases, and the likelihood of carbon monoxide being generated due to incomplete combustion also increases.

[0038] The control device 13 selects the ratio that was outside the acceptable range if at least one of the first ratio and the second ratio is outside the acceptable range defined for each of them. The control device 13 determines whether the difference between the second value, which is defined as a set value for each of the two raw materials used to calculate the selected ratio, and the first value for each of the two raw materials is greater than or equal to a threshold. In the first ratio, the two raw materials are steam and raw fuel. In the second ratio, the two raw materials are air and fuel.

[0039] The control device 13 changes the set value for one of the raw materials to the first value if the difference between the first value and the second value is greater than or equal to a threshold. The control device 13 also changes the set value for the other raw material. The threshold for any raw material is, for example, the adjustment error of the first adjustment mechanism 18, the second adjustment mechanism 19, or the third adjustment mechanism 20. Generally, the threshold is narrower than the tolerance range, and if one of the first ratio and the second ratio is outside the tolerance range, the difference between the first value and the second value of at least one of the two raw materials used to calculate that one is greater than or equal to 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 if the difference between the first value and the second value is greater than or equal to a threshold, and the first value is smaller than the second value. For example, if the first ratio is outside the acceptable range, and the difference obtained by subtracting the first value from the second value of the raw fuel is greater than or equal to a threshold, the control device 13 changes the set value of the raw fuel to the first value. On the other hand, even if the first ratio is outside the acceptable range, and the difference obtained by subtracting the second value from the first value of the raw fuel is greater than or equal to a threshold, the control device 13 maintains the set value of the raw fuel at the second value.

[0041] The control device 13 may change the set value of the other raw material relative to the first raw material whose set value has been changed to a first value, to a value based on the set value set for the first value and the selected ratio (first ratio or second ratio). The set value may be set to any value included in the above-mentioned tolerance range.

[0042] For example, if the control device 13 determines that the first ratio is outside the acceptable range and changes the raw fuel setting to the first value, it 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 setting 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 calculates a value obtained by converting the calculated number of moles of steam into a steam supply amount. The control device 13 changes the steam setting to the converted value.

[0043] In a configuration where the control device 13 determines the setting value of each raw material according to the set value of the generated power corresponding to the user's requested power, the control device 13 may change the setting value of one of the raw materials that satisfies the above conditions to the first value, and then change the set value of the generated power. Specifically, the control device 13 may calculate a fourth value by multiplying the third value specified in the set value of the generated power 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 generated power from the third value to the fourth value. Next, the control device 13 may change the setting values ​​of other raw materials, including the other raw material, for the one raw material in question to the value determined according to the predetermined correspondence and the fourth value described above. Therefore, the S / C and A / F calculated using the setting values ​​of each raw material determined according to the set value of the generated power may match the set values ​​of S / C and A / F.

[0044] The control device 13 may obtain a new first value after the set value of the generated power has been changed to the fourth value, by detecting the supply amount of each raw material. The control device 13 may calculate the difference between the new first value for each raw material and the value set for each of those raw materials, in other words, the first value when the set value of the generated power is the third value. If the difference is greater than or equal to a threshold, 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 generated power to the third value after a predetermined time has elapsed since changing it to the fourth value. After returning the set value of the generated power to the third value, the control device 13 may obtain a first value which is the supply amount of each raw material detected. Based on the first value, the control device 13 may calculate the first ratio and the second ratio.

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

[0047] Alternatively, the control device 13 may shut down the fuel cell device 10 if at least one of the calculated first ratio and second ratio is outside the acceptable range. Before shutting down the fuel cell device 10, the control device 13 may perform at least one more step of changing the set value of the generated power to a fourth value, allowing a predetermined time to elapse, changing it to a third value, and determining whether the first ratio and second ratio are outside the acceptable range before shutting down the fuel cell device 10.

[0048] Next, the first tolerance range maintenance process performed by the control device 13 in this embodiment will be explained using the flowchart in Figure 2. The first tolerance range maintenance process is started, for example, periodically or periodically.

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

[0050] In step S101, the control device 13 calculates S / C and A / F based on the first values ​​of each raw material obtained in step S100. After 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 permissible range defined for S / C and A / F, respectively. If it is not outside the permissible range, the first permissible range maintenance process ends. If it is outside the permissible range, the process proceeds to step S103.

[0052] In step S103, the control device 13 calculates the difference between the second value, which is set as a set value for each raw material, and the first value obtained in step S100. After the calculation, the process proceeds to step S104.

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

[0054] In step S105, the control device 13 determines whether the second value of the raw material 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 raw material setting value selected in step S104 to the first value obtained 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 power generation based on the first and second values ​​of the raw materials selected in step S104. After the change, the process proceeds to step S108.

[0057] In step S108, the control device 13 changes the setting values ​​of each raw material other than the raw material selected in step S104, according to the setting value of the power generation that was changed in step S107. After the change, the process proceeds to step S109.

[0058] In step S109, the control device 13 again obtains the supply amounts of raw fuel, water, and air from the first flow meter 14, the second flow meter 15, and the third flow meter 16 as first values. After obtaining these values, 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 calculation, the process proceeds to step S111.

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

[0061] In step S112, the control device 13 stops the fuel cell device 10. After stopping, the first tolerance range maintenance process is completed.

[0062] Next, the second tolerance range maintenance process performed by the control device 13 in this embodiment will be explained using the flowchart in Figure 3. The second tolerance range maintenance process is started, for example, periodically or periodically.

[0063] From step S200 to S208, the control device 13 performs the same processing as from step S100 to S108 of the first tolerance range maintenance process. In step S208, after changing the set values ​​of each raw material, the process proceeds to step S209.

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

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

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

[0067] In step S212, the control device 13 calculates S / C and A / F based on the first values ​​of each raw material obtained in step S211. After 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 permissible range defined for S / C and A / F, respectively. If it is not outside the permissible range, the second permissible range maintenance process ends. If it is outside the permissible range, the process proceeds to step S214.

[0069] In step S214, the control device 13 sets the set value of the generated power to a third value. After setting, the second tolerance range maintenance process is completed.

[0070] Next, the third tolerance range maintenance process performed by the control device 13 in this embodiment will be explained using the flowchart in Figure 4. The third tolerance range maintenance process is started, for example, periodically or periodically.

[0071] From step S300 to S313, the control device 13 performs the same processing as from step S200 to S213 of the second tolerance range maintenance process. If at least one of S / C and A / F is outside the tolerance range defined for S / C and A / F respectively in step S313, the process proceeds to step S314.

[0072] In step S314, the control device 13 stops the fuel cell device 10. After stopping, the third tolerance range maintenance process is completed.

[0073] The fuel cell device 10 of this embodiment, configured as described above, comprises a reformer 11 that generates fuel by reforming raw fuel and steam, a fuel cell 12 that generates electricity using 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 fuel cell 12 at set values. The control device 13 obtains a first value by detecting the supply amount of each raw material, calculates a first ratio and a second ratio based on each first value, and if at least one of the first ratio and the second ratio falls outside the permissible range set for each, the control device 13 changes the set value for that raw material to the first value when the difference between the second value, which is set as the set value for one of the two raw materials to calculate, and the first value for that raw material is greater than or equal to a threshold, and changes the set value for the other raw material. As mentioned above, when S / C and A / F fall outside the permissible range, the amount of carbon monoxide generated increases. The generated carbon monoxide can be burned using a combustion catalyst, but it is desirable to reduce the original amount generated. Under normal conditions, the flow rates of raw fuel, water, and air are set and controlled to maintain the first ratio (S / C) and the second ratio (A / F) within acceptable limits. However, malfunctions of the first adjustment mechanism 18, the second adjustment mechanism 19, and the third adjustment mechanism 20 may make it difficult to adjust either water or raw fuel, or fuel or air, to the set values. In such situations, it may be difficult to keep S / C and A / F within acceptable limits even with normal control. On the other hand, the fuel cell device 10 having the above configuration can determine that the difference between the detected first value and the second value set as the set value is greater than or equal to a threshold, and can therefore change the set value of a raw material that is difficult to maintain at the set value to a value that can be maintained. Furthermore, the control device 13 can also change the set value of the other raw material in the calculation of S / C or A / F for that raw material. Therefore, the fuel cell device 10 can keep S / C and A / F within acceptable limits even when it is difficult to maintain the supply amount of any raw material at the original set value.

[0074] Furthermore, in the fuel cell device 10, the control device 13 changes the set value for one of the raw materials to the first value when the difference between the first and second values ​​of that raw material is greater than or equal to a threshold, and the first value is smaller than the second value. The fuel cell device 10 is normally assumed to be operating at its rated capacity. Therefore, for raw materials for which it is difficult to maintain the supply amount at the set value, it may be difficult to maintain the other raw material in the calculation of S / C or A / F at an increased set value. In response to such situations, the control device 13 adds the condition that the detected first value is the set value (second value) when changing the set value, thereby limiting the situation to one where S / C and A / F can be easily kept within the acceptable range. Consequently, the fuel cell device 10 increases the likelihood of exhibiting the effect of keeping S / C and A / F within the acceptable range.

[0075] Furthermore, in the fuel cell device 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 the other outside the acceptable range. With this configuration, the fuel cell device 10 further increases the possibility of keeping S / C and A / F within the acceptable range.

[0076] Furthermore, in the fuel cell device 10, the control device 13 determines the setting value for each raw material to a value that has a predetermined correspondence with the set value of the required power generation. After changing the setting value for one of the two raw materials to the first value, it changes the setting value for the other raw material to the fourth value, which is calculated by multiplying the third value, which is set in the power generation setting value, by a coefficient obtained by dividing the first value by the second value. Based on the fourth value and the predetermined correspondence, the setting value for the other raw material is changed. 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. Also, changing the supply amount of air or water in order to keep the S / C and A / F within the allowable range will result in a change in the supply amount of raw fuel. In response to such events, the control device 13 in the fuel cell device 10 calculates the power generation corresponding to the amount of raw material that can be supplied when it is difficult to maintain the supply amount at the set value, and changes the setting values ​​of the other raw materials according to the power generation. 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 a set value, using the relationship between the generated power and the set values ​​of the supply amounts of each raw material, which can also be used during normal operation.

[0077] Furthermore, in the fuel cell device 10, the control device 13 calculates the first and second ratios using the raw material setting values ​​determined according to the set value of the generated power, and these ratios match the setting values ​​for the first and second ratios. This configuration further increases the possibility of keeping the S / C and A / F within acceptable limits for the fuel cell device 10.

[0078] Furthermore, in the fuel cell device 10, the control device 13 returns the set value of the generated power to the third value after a predetermined time has elapsed since the change to the fourth value. Changing the set value of the generated power causes a surplus or deficit of generated power. Therefore, the fuel cell device 10 may, after reducing the S / C and A / F within an acceptable range by changing the set value of the generated power, attempt to bring the generated power closer to the original set value again.

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

[0080] Furthermore, in the fuel cell device 10, the control device 13, after returning the set value of the generated power to the third value, obtains a first value by detecting the supply amount of each raw material, calculates a first ratio and a second ratio based on each first value, and stops operation if at least one of the first ratio and the second ratio is outside the acceptable range. Frequent changes to the set values ​​of the generated power and each raw material are undesirable from the viewpoint of stable operation. Therefore, the fuel cell device 10 having the above configuration can avoid continuing unstable operation by stopping operation.

[0081] Furthermore, in the fuel cell device 10, after changing the set value of the generated power to the fourth value, the control device 13 obtains a new first value by detecting the supply amount of each raw material, and stops the fuel cell device 10 if the difference between the new first value of each raw material and the value set for each raw material is greater than or equal to a threshold. If the supply amount of raw materials cannot be maintained even after changing the set value to a value that is considered to be sustainable, it is possible that 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 has failed, there is a communication abnormality between these devices and the control device 13, and there is a blockage in the first supply path 23, the second supply path 24, and the third supply path 25. In response to such events, the fuel cell device 10 having the above configuration may determine that it is in a faulty state and stop operation.

[0082] In one embodiment, (1) the fuel cell device is A fuel cell system comprising: a reformer that produces fuel by reforming 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, air, raw fuel, and steam, to the fuel cell and the reformer at set values, The control device is A first value is obtained which is the supply amount of each of the aforementioned raw materials. Based on each of the aforementioned first values, a first ratio, which is the ratio of moles of water vapor to moles of carbon in the raw fuel, and a second ratio, which is the ratio of the amount of fuel supplied to air, are calculated. If at least one of the first ratio and the second ratio falls outside the tolerance range set for each, and the difference between the second value, which is set as the setting value for one of the two raw materials used to calculate the first ratio, and the first value for that raw material is greater than or equal to a threshold, the setting value for that raw material is changed to the first value, and the setting value for the other of the two raw materials is changed.

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

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

[0085] (4) In the fuel cell device described in (1) or (2) above, The control device is In the fuel cell module, the set values ​​for each of the raw materials are determined to correspond to a predetermined set value for the required power generation, After changing the setting value for one of the two raw materials to the first value, the setting value for the generated power is changed to a fourth value calculated by multiplying the third value by a coefficient obtained by dividing the first value by the second value, Based on the fourth value and the predetermined correspondence, the setting value of the other raw material is changed.

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

[0087] (6) In the fuel cell device described in (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 described in (6) above, The control device, after returning the set value of the generated power to the third value, obtains a first value that detects the supply amount of each of the raw materials, calculates the first ratio and the second ratio based on each of the first values, and if at least one of the first ratio and the second ratio is outside the allowable range, sets the upper limit of the generated power to the third value.

[0089] (8) In the fuel cell device described in (6) above, The control device, after returning the set value of the generated power to the third value, obtains a first value that detects the supply amount of each of the raw materials, calculates the first ratio and the second ratio based on each of the first values, and if at least one of the first ratio and the second ratio falls outside the allowable range, it shuts down the fuel cell module.

[0090] (9) In the fuel cell device described in (6) above, After changing the set value of the generated power to the fourth value, the control device obtains a new first value by detecting 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 set as the set value for each of the raw materials is greater than or equal to the threshold, the control device shuts down the fuel cell module.

[0091] In one embodiment, (10) the control method is The system comprises a reformer that produces fuel by reforming raw fuel and steam, and a fuel cell that generates electricity using the fuel and air. A control method for a fuel cell system that controls the supply amounts of raw materials, including the fuel, air, raw fuel, and steam, to the reformer and the fuel cell to maintain them at set values, A first value is obtained which is the supply amount of each of the aforementioned raw materials. Based on each of the aforementioned first values, a first ratio is calculated, which is the 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 is calculated, which is the ratio of the amount of fuel supplied to air. If at least one of the first ratio and the second ratio falls outside the tolerance range set for each, and the difference between the second value, which is set as the setting value for one of the two raw materials used to calculate the first ratio, and the first value for that raw material is greater than or equal to a threshold, the setting value for that raw material is changed to the first value, and the setting value for the other of the two raw materials is changed.

[0092] While embodiments of the fuel cell device 10 have been described above, embodiments of the present disclosure may also include not only methods or programs for implementing the device, but also a storage medium on which a program is recorded (for example, an optical disc, magneto-optical disc, CD-ROM, CD-R, CD-RW, magnetic tape, hard disk, or memory card).

[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 embedded in an operating system. Moreover, the program may or may not be configured so that all processing is performed only on the CPU on the control board. The program may also be configured so that some or all of its processing is performed by another processing unit implemented on an expansion board or expansion unit attached to the board, as needed.

[0094] The diagrams illustrating the embodiments described herein are schematic. Dimensions and proportions shown in the drawings do not necessarily correspond to actual dimensions.

[0095] While embodiments relating to this disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are within the scope of this disclosure. For example, the functions and other elements included in each component can be rearranged in a logically consistent manner, and multiple components can be combined into one or separated.

[0096] All of the constituent elements described in this disclosure, and / or all of the disclosed methods or steps of processing, can be combined in any combination except for any combination in which these features are mutually exclusive. Furthermore, each of the features described in this disclosure can be replaced by an alternative feature that works for the same, equivalent, or similar purpose, unless expressly disregarded. Thus, unless expressly disregarded, each of the disclosed features is merely an example of a comprehensive set of identical or equivalent features.

[0097] Furthermore, the embodiments relating to this disclosure are not limited to any specific configuration of the embodiments described above. The embodiments relating to this disclosure can be extended to all novel features or combinations thereof described herein, or all novel methods or processing steps or combinations thereof described herein.

[0098] In this disclosure, the designations "First," "Second," etc., are identifiers used to distinguish the configurations. Configurations distinguished by the designations "First," "Second," etc., in this disclosure may have their numbers swapped. For example, the first flow meter may have its identifiers "First" and "Second" swapped with those of the second flow meter. The swapping of identifiers occurs simultaneously. The configurations remain distinguishable even after the swapping of identifiers. Identifiers may be deleted. Configurations from which identifiers have been deleted are distinguished by codes. The designations "First," "Second," etc., in this disclosure should not be used solely to interpret the order of the configurations or to justify the existence of smaller numbered identifiers. [Explanation of Symbols]

[0099] 10 Fuel cell device 11. Modifier 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 section 22 Combustion section 23. First supply channel 24 Second supply channel 25. Third supply channel 26 Fuel cell modules

Claims

1. A fuel cell system comprising: a reformer that produces fuel by reforming 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, air, raw fuel, and steam, to the fuel cell and the reformer at set values, The control device is A first value is obtained which is the supply amount of each of the aforementioned raw materials. Based on each of the aforementioned first values, a first ratio, which is the ratio of moles of water vapor to moles of carbon in the raw fuel, and a second ratio, which is the ratio of the amount of fuel supplied to air, are calculated. If at least one of the first ratio and the second ratio falls outside the tolerance range set for each, and the difference between the second value, which is set as the setting value for one of the two raw materials used to calculate the first ratio, and the first value for that raw material is greater than or equal to a threshold, the setting value for that raw material is changed to the first value, and the setting value for the other of the two raw materials is changed. Fuel cell equipment.

2. The control device changes the set value for the raw material to the first value if the difference between the first value and the second value of one of the raw materials is greater than or equal to a threshold, and the first value is smaller than the second value. The fuel cell apparatus according to claim 1.

3. The control device changes the set value for the other raw material to a value based on the set value set as the ratio of the first value and the one outside the tolerance range. The fuel cell device according to claim 1 or 2.

4. The control device is The set values ​​for each of the aforementioned raw materials are determined to correspond to a predetermined value with the set value of the required power generation, After changing the setting value for one of the two raw materials to the first value, the setting value for the generated power is changed to a fourth value calculated by multiplying the third value by a coefficient obtained by dividing the first value by the second value. Based on the fourth value and the predetermined correspondence, the setting value of the other raw material is changed. The fuel cell device according to claim 1 or 2.

5. The first and second ratios, calculated using the raw material set values ​​determined according to the set value of the generated power, coincide with the set values ​​for the first and second ratios. The fuel cell apparatus according to claim 4.

6. The control device will return 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. The fuel cell apparatus according to claim 4.

7. The control device, after returning the set value of the generated power to the third value, obtains a first value that detects the supply amount of each of the raw materials, calculates the first ratio and the second ratio based on each of the first values, and if at least one of the first ratio and the second ratio is outside the allowable range, sets the upper limit of the generated power to the third value. The fuel cell apparatus according to claim 6.

8. The control device, after returning the set value of the generated power to the third value, obtains a first value that detects the supply amount of each of the raw materials, calculates the first ratio and the second ratio based on each of the first values, and if at least one of the first ratio and the second ratio falls outside the allowable range, it shuts down the fuel cell device. The fuel cell apparatus according to claim 6.

9. After changing the set value of the generated power to the fourth value, the control device obtains a new first value by detecting the supply amount of each of the raw materials, and if the difference between the new first value for each of the raw materials and the value set as the set value for each of the raw materials is greater than or equal to the threshold, the control device stops the fuel cell system. The fuel cell apparatus according to claim 6.

10. A control method for a fuel cell system comprising a reformer that produces fuel by reforming raw fuel and steam, and a fuel cell that generates electricity using the fuel and air, wherein the amount of raw materials including the fuel, air, raw fuel, and steam supplied to the reformer and the fuel cell is controlled to maintain a set value, A first value is obtained which is the supply amount of each of the aforementioned raw materials. Based on each of the aforementioned first values, a first ratio is calculated, which is the 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 is calculated, which is the ratio of the amount of fuel supplied to air. If at least one of the first ratio and the second ratio falls outside the tolerance range set for each, and the difference between the second value, which is set as the setting value for one of the two raw materials used to calculate the first ratio, and the first value for that raw material is greater than or equal to a threshold, the setting value for that raw material is changed to the first value, and the setting value for the other of the two raw materials is changed. A control method for a fuel cell system.

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