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WO2012091033A1 - Fuel cell system - Google Patents

Fuel cell system Download PDF

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Publication number
WO2012091033A1
WO2012091033A1 PCT/JP2011/080264 JP2011080264W WO2012091033A1 WO 2012091033 A1 WO2012091033 A1 WO 2012091033A1 JP 2011080264 W JP2011080264 W JP 2011080264W WO 2012091033 A1 WO2012091033 A1 WO 2012091033A1
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WO
WIPO (PCT)
Prior art keywords
fuel
moving average
average value
unit
cell system
Prior art date
Application number
PCT/JP2011/080264
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French (fr)
Japanese (ja)
Inventor
環樹 水野
定兼　修
Original Assignee
Ｊｘ日鉱日石エネルギー株式会社
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Publication of WO2012091033A1 publication Critical patent/WO2012091033A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04313—Processes for controlling fuel cells or fuel cell systems characterised by the detection or assessment of variables; characterised by the detection or assessment of failure or abnormal function
    • H01M8/04537—Electric variables
    • H01M8/04544—Voltage
    • H01M8/04559—Voltage of fuel cell stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/04—Auxiliary arrangements, e.g. for control of pressure or for circulation of fluids
    • H01M8/04298—Processes for controlling fuel cells or fuel cell systems
    • H01M8/04992—Processes for controlling fuel cells or fuel cell systems characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/06—Combination of fuel cells with means for production of reactants or for treatment of residues
    • H01M8/0606—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants
    • H01M8/0612—Combination of fuel cells with means for production of reactants or for treatment of residues with means for production of gaseous reactants from carbon-containing material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a fuel cell system.
  • the fuel cell system can be constructed assuming that the properties of the fuel supplied to the cell stack are constant. For this reason, when the fuel cell system is installed in an environment in which the properties of the fuel fluctuate, there is a risk of causing deterioration of the heat balance in the system and progress of deterioration of the cell stack.
  • fuel property measuring means for measuring the property and flow rate of the fuel is provided in the fuel supply unit, and the water vapor supply amount and the fuel supply amount are based on the measurement results.
  • Various parameters such as are controlled.
  • the conventional fuel property measuring means as described above actually requires a configuration for measuring a plurality of factors such as fuel composition, calorific value, and flow rate. Therefore, the configuration of the fuel cell system may be complicated.
  • the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel cell system capable of detecting a change in fuel properties with a simple configuration.
  • a fuel cell system includes a hydrogen generation unit that generates a hydrogen-containing gas using a fuel containing hydrogen, a cell stack that generates power using the hydrogen-containing gas, and A voltage detection unit that detects a voltage output from the cell stack, an operation state determination unit that determines whether or not the fuel cell system is in a rated operation state, and an operation state determination When the unit determines that the fuel cell system is in the rated operation state, the first moving average value of the voltage detected by the voltage detecting unit and the second moving average value of a certain time before the current time are calculated. And a property change determination unit that determines whether there is a change in the property of the fuel based on a comparison between the first moving average value and the second moving average value.
  • a fuel cell system includes a hydrogen generation unit that generates a hydrogen-containing gas using a hydrogen-containing fuel, a cell stack that generates power using the hydrogen-containing gas, and a cell stack.
  • the determination unit and the operation state determination unit determine that the fuel cell system is in the rated operation state
  • the current first moving average value of the temperature detected by the temperature detection unit and the first predetermined time before the current time A property change determining unit that calculates a two-moving average value and determines whether there is a change in the property of the fuel based on a comparison between the first moving average value and the second moving average value.
  • This fuel cell system can detect changes in fuel properties with a simple configuration.
  • FIG. 1 is a diagram showing an embodiment of a fuel cell system according to the present invention. It is a figure which shows the functional component of a control part. It is a flowchart which shows an example of the diagnostic process by a control part. It is a flowchart which shows an example of judgment of diagnosis start conditions. It is a figure which shows the relationship between the property of a fuel, and the output of a cell stack. It is a figure which shows the functional component of the control part which concerns on a modification. It is a flowchart which shows an example of the diagnostic process by the control part which concerns on a modification. It is a figure which shows the relationship between the property of the fuel which concerns on a modification, and the output of a cell stack.
  • the fuel cell system 1 includes a desulfurization unit 2, a water vaporization unit 3, a hydrogen generation unit 4, a cell stack 5, an off-gas combustion unit 6, a hydrogen-containing fuel supply unit 7, The water supply part 8, the oxidizing agent supply part 9, the power conditioner 10, and the control part 11 are provided.
  • the fuel cell system 1 generates power in the cell stack 5 using a hydrogen-containing fuel and an oxidant.
  • the type of the cell stack 5 in the fuel cell system 1 is not particularly limited, and examples thereof include a polymer electrolyte fuel cell (PEFC), a solid oxide fuel cell (SOFC), and phosphoric acid.
  • a fuel cell (PAFC: Phosphoric Acid Fuel Cell), a molten carbonate fuel cell (MCFC: Molten Carbonate Fuel Cell), and other types can be employed. 1 may be appropriately omitted depending on the type of cell stack 5, the type of hydrogen-containing fuel, the reforming method, and the like.
  • hydrocarbon fuel a compound containing carbon and hydrogen in the molecule (may contain other elements such as oxygen) or a mixture thereof is used.
  • hydrocarbon fuels include hydrocarbons, alcohols, ethers, and biofuels. These hydrocarbon fuels are derived from conventional fossil fuels such as petroleum and coal, and synthetic systems such as synthesis gas. Those derived from fuel and those derived from biomass can be used as appropriate. Specific examples of hydrocarbons include methane, ethane, propane, butane, natural gas, LPG (liquefied petroleum gas), city gas, town gas, gasoline, naphtha, kerosene, and light oil. Examples of alcohols include methanol and ethanol. Examples of ethers include dimethyl ether. Examples of biofuels include biogas, bioethanol, biodiesel, and biojet.
  • oxygen-enriched air for example, air, pure oxygen gas (which may contain impurities that are difficult to remove by a normal removal method), or oxygen-enriched air is used.
  • the desulfurization unit 2 desulfurizes the hydrogen-containing fuel supplied to the hydrogen generation unit 4.
  • the desulfurization part 2 has a desulfurization catalyst for removing sulfur compounds contained in the hydrogen-containing fuel.
  • a desulfurization method of the desulfurization unit 2 for example, an adsorptive desulfurization method that adsorbs and removes sulfur compounds and a hydrodesulfurization method that removes sulfur compounds by reacting with hydrogen are employed.
  • the desulfurization unit 2 supplies the desulfurized hydrogen-containing fuel to the hydrogen generation unit 4.
  • the water vaporization unit 3 generates water vapor supplied to the hydrogen generation unit 4 by heating and vaporizing water.
  • heat generated in the fuel cell system 1 such as recovering the heat of the hydrogen generation unit 4, the heat of the off-gas combustion unit 6, or the heat of the exhaust gas may be used.
  • FIG. 1 only heat supplied from the off-gas combustion unit 6 to the hydrogen generation unit 4 is described as an example, but the present invention is not limited to this.
  • the water vaporization unit 3 supplies the generated water vapor to the hydrogen generation unit 4.
  • the hydrogen generation unit 4 generates a hydrogen rich gas using the hydrogen-containing fuel from the desulfurization unit 2.
  • the hydrogen generator 4 has a reformer that reforms the hydrogen-containing fuel with a reforming catalyst.
  • the reforming method in the hydrogen generating unit 4 is not particularly limited, and for example, steam reforming, partial oxidation reforming, autothermal reforming, and other reforming methods can be employed.
  • the hydrogen generator 4 may have a configuration for adjusting the properties in addition to the reformer reformed by the reforming catalyst depending on the properties of the hydrogen rich gas required for the cell stack 5.
  • the hydrogen generation unit 4 is configured to remove carbon monoxide in the hydrogen-rich gas. (For example, a shift reaction part and a selective oxidation reaction part).
  • the hydrogen generation unit 4 supplies a hydrogen rich gas to the anode 12 of the cell stack 5.
  • the cell stack 5 generates power using the hydrogen rich gas from the hydrogen generation unit 4 and the oxidant from the oxidant supply unit 9.
  • the cell stack 5 includes an anode 12 to which a hydrogen-rich gas is supplied, a cathode 13 to which an oxidant is supplied, and an electrolyte 14 disposed between the anode 12 and the cathode 13.
  • the cell stack 5 supplies power to the outside via the power conditioner 10.
  • the cell stack 5 supplies the hydrogen rich gas and the oxidant, which have not been used for power generation, to the off gas combustion unit 6 as off gas.
  • a combustion section for example, a combustor that heats the reformer
  • the hydrogen generation section 4 may be shared with the off-gas combustion section 6.
  • the off gas combustion unit 6 burns off gas supplied from the cell stack 5.
  • the heat generated by the off-gas combustion unit 6 is supplied to the hydrogen generation unit 4 and used for generation of a hydrogen rich gas in the hydrogen generation unit 4.
  • the hydrogen-containing fuel supply unit 7 supplies hydrogen-containing fuel to the desulfurization unit 2.
  • the water supply unit 8 supplies water to the water vaporization unit 3.
  • the oxidant supply unit 9 supplies an oxidant to the cathode 13 of the cell stack 5.
  • the hydrogen-containing fuel supply unit 7, the water supply unit 8, and the oxidant supply unit 9 are configured by a pump, for example, and are driven based on a control signal from the control unit 11.
  • the power conditioner 10 adjusts the power from the cell stack 5 according to the external power usage state. For example, the power conditioner 10 performs a process of converting a voltage and a process of converting DC power into AC power.
  • the control unit 11 performs control processing for the entire fuel cell system 1.
  • the control unit 11 is configured by a device including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface, for example.
  • the control unit 11 is electrically connected to a hydrogen-containing fuel supply unit 7, a water supply unit 8, an oxidant supply unit 9, a power conditioner 10, and other sensors and auxiliary equipment not shown.
  • the control unit 11 acquires various signals generated in the fuel cell system 1 and outputs a control signal to each device in the fuel cell system 1.
  • control executed by the control unit 11 will be described in more detail.
  • the control unit 11 is a part that outputs a control signal to each device in the fuel cell system 1, but in addition to this, the properties (heat amount, composition, etc.) of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7. Diagnosis processing for diagnosing a change in the output of the fuel cell system 1 due to the change in the value is executed.
  • control unit 11 includes a diagnosis start condition determination unit 101, an operation state determination unit 102, a voltage detection unit 103, and a property change determination unit 104 as functional components. And a fuel supply table selection unit 105.
  • the diagnosis start condition determination unit 101 is a part that determines whether or not to start execution of diagnosis processing. Various conditions can be applied as the diagnosis start condition. For example, whether or not a predetermined time has elapsed since the fuel cell system 1 started power generation, or a hot water tank (not shown) connected to the fuel cell system 1 The remaining amount of water is small and there is a demand for hot water (the fuel cell system 1 is in a state of recovering heat).
  • the predetermined time after starting the power generation is set to 1000 hours, for example.
  • the operation state determination unit 102 is a part that determines whether or not the fuel cell system 1 is in a rated operation state.
  • the rated operation state is an operation state in which the power generated by the cell stack 5 is the maximum power in the specification, and is a state in which the voltage / current operates stably.
  • the operation state determination unit 102 determines that the fuel cell system 1 is in the rated operation state when, for example, the change in the moving average value of the voltage output from the cell stack 5 is equal to or less than the threshold value for a certain time (for example, 15 minutes). to decide.
  • the voltage detection unit 103 is a part that detects a voltage output from the cell stack 5 to the power conditioner 10.
  • the voltage detector 103 constantly detects the voltage output from the cell stack 5 to the power conditioner 10 while the fuel cell system 1 is generating power.
  • the property change determination unit 104 is a part that determines whether or not the property of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 has changed. More specifically, the property change determination unit 104 determines the first current of the voltage detected by the voltage detection unit 103 when the operation state determination unit 102 determines that the fuel cell system 1 is in the rated operation state.
  • the moving average value Vcc_now and the second moving average value Vcc_before for a certain time before the current time are calculated.
  • the first moving average value Vcc_now and the second moving average value Vcc_before may be a moving average value of voltage for 15 minutes, for example.
  • the second moving average value Vcc_before may be a moving average value 10 hours before the first moving average value Vcc_now, for example.
  • the property change determination unit 104 compares the first moving average value Vcc_now and the second moving average value Vcc_before, and compares the first moving average value Vcc_before with the second moving average value Vcc_before. It is determined whether or not the amount of change in the 1 moving average value Vcc_now exceeds a threshold value.
  • the upper limit threshold value may be, for example, the second moving average value Vcc_before ⁇ 1.03
  • the lower limit threshold value may be, for example, the second moving average value Vcc_before ⁇ 0.97.
  • the comparison between the first moving average value Vcc_now and the second moving average value Vcc_before as described above may be executed at regular intervals or may be executed constantly.
  • the fuel supply table selection unit 105 is a part that changes the supply table of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 based on the determination result in the property change determination unit 104.
  • the property change determination unit 104 determines that the first moving average value Vcc_now exceeds the second moving average value Vcc_before ⁇ 1.03, for example, the fuel supply table selection unit 105 determines that the fuel for the high calorific value is high. Select the supply table to control the fuel supply.
  • the property change determining unit 104 determines that the first moving average value Vcc_now is less than the second moving average value Vcc_before ⁇ 0.97, for example, the fuel supply table selecting unit 105 uses the low heating value.
  • a fuel supply table is selected to control fuel supply.
  • the high calorific value fuel supply table is a table used when the calorific value of the fuel is higher than before.
  • the fuel flow rate is controlled to 1.0 L / min and the water is controlled to 7 g / min on the assumption that the fuel utilization rate and S / C are constant.
  • the low calorific value fuel supply table is a table used when the calorific value of the fuel is lower than the conventional one.
  • the fuel flow rate is controlled to, for example, 1.5 L / min and water is 10.5 g / min, assuming that the fuel utilization rate and S / C are constant.
  • FIG. 3 is a flowchart illustrating an example of diagnosis processing by the control unit.
  • step S01 when the fuel cell system 1 starts power generation, detection of the voltage output from the cell stack 5 is started (step S01). Next, based on the amount of change in the moving average value of the voltage output from the cell stack 5, it is determined whether or not the fuel cell system 1 is in the rated operation state (step S02).
  • step S02 when it is determined that the fuel cell system 1 is in the rated operation state, the diagnosis start condition is determined (step S03, step S04).
  • the diagnosis start condition for example, as shown in FIG. 4, it is first determined whether or not a predetermined time has elapsed since the start of power generation (step S21). Next, it is determined whether or not the demand for hot water is large (step S22). If both the steps S21 and S22 are satisfied, it is determined that the diagnosis start condition is satisfied (step S23). If either of steps S21 and S22 is not satisfied, it is determined that the diagnosis start condition is not satisfied (step S24). If it is determined that the diagnosis start condition is not satisfied, the processes from step S02 to step S04 are repeated.
  • the current first moving average value Vcc_now of the voltage detected by the voltage detection unit 103 and the second moving average value Vcc_before for a certain time before the current time. Is calculated (step S05).
  • step S06 if the first moving average value Vcc_now is within the threshold value range, it is determined that there is no change in the properties of the fuel, and after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends ( Step S11). On the other hand, if the first moving average value Vcc_now is outside the threshold value range in step S06, the magnitude of the first moving average value Vcc_now and the second moving average value Vcc_before is determined (step S07).
  • step S07 when the first moving average value Vcc_now is larger than the second moving average value Vcc_before, it is determined that the property of the fuel has changed and the heat value of the fuel is higher than the conventional value, and the high heat value is high.
  • the fuel supply is controlled based on the fuel supply table (step S08).
  • step S09 when the first moving average value Vcc_now is smaller than the second moving average value Vcc_before, it is determined that the fuel property has changed and the heat value of the fuel is lower than that of the conventional fuel.
  • the supply of fuel is controlled based on the supply table (step S09). In any case, when the fuel supply table is changed, the second moving average value Vcc_before is replaced with the first moving average value Vcc_now (step S10). Then, after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends (step S11).
  • the moving average value of the voltage output from the cell stack 5 is obtained. If there is a change, it is determined that the fuel properties have changed. Therefore, compared with the conventional method of measuring a plurality of factors relating to the fuel property, the configuration necessary for determining whether or not the property of the fuel has changed can be simplified.
  • FIG. 5 is a diagram showing the relationship between fuel properties and cell stack output.
  • heat amount of a fuel becomes lower than before is illustrated.
  • the voltage output from the cell stack 5 decreases.
  • the control unit 11 detects a change in the properties of the fuel and the fuel supply table is changed, the decrease in the heat quantity of the fuel is compensated by the increase in the flow rate, and the voltage output from the cell stack 5 It recovers to the same value as before the change of properties.
  • the modified example is different from the above-described embodiment in that the change in the property of the fuel is diagnosed by detecting the temperature of the off-gas combustion unit 6 instead of detecting the voltage output from the cell stack 5.
  • the control unit 21 in the modification example includes, as functional components, a diagnosis start condition determination unit 201, an operation state determination unit 202, a temperature detection unit 203, and a property change determination as illustrated in FIG. 6.
  • Unit 204 and a fuel supply table selection unit 205 are the same as the diagnosis start condition determination unit 101 described above, and a description thereof will be omitted.
  • the operation state determination unit 202 is a part that determines whether or not the fuel cell system 1 is in a rated operation state.
  • the operation state determination unit 202 determines that the fuel cell system 1 is in the rated operation state when, for example, the change in the moving average value of the temperature of the off-gas combustion unit 6 is equal to or less than the threshold value for a certain time (for example, 15 minutes). .
  • the temperature detection unit 203 is a part that detects the temperature of the off-gas combustion unit 6.
  • the temperature detection unit 203 always detects the temperature of the off-gas combustion unit 6 while the fuel cell system 1 is generating power.
  • the property change determination unit 204 is a part that determines whether or not the property of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 has changed. More specifically, the property change determination unit 204 determines the temperature of the off-gas combustion unit 6 detected by the temperature detection unit 203 when the operation state determination unit 202 determines that the fuel cell system 1 is in the rated operation state.
  • the first moving average value Tcc_now at the present time and the second moving average value Tcc_before for a certain time before the current time are calculated.
  • the first moving average value Tcc_now and the second moving average value Tcc_before may be, for example, moving average values of temperatures for 15 minutes.
  • the second moving average value Tcc_before may be a moving average value 10 hours before the first moving average value Tcc_now, for example.
  • the property change determining unit 204 compares the first moving average value Tcc_now and the second moving average value Tcc_before, and compares the first moving average value Tcc_before with the second moving average value Tcc_before. It is determined whether or not the amount of change in the 1 moving average value Tcc_now exceeds a threshold value.
  • the upper limit threshold value may be, for example, the second moving average value Tcc_before ⁇ 1.03
  • the lower limit threshold value may be, for example, the second moving average value Tcc_before ⁇ 0.97.
  • the comparison between the first moving average value Tcc_now and the second moving average value Tcc_before as described above may be executed at regular intervals or may be executed constantly.
  • the fuel supply table selection unit 205 is a part that changes the supply table of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 based on the determination result in the property change determination unit 204.
  • the property change determination unit 204 determines that the first moving average value Tcc_now exceeds the second moving average value Tcc_before ⁇ 1.03, for example, the fuel supply table selection unit 205 has a high heating value fuel. Select the supply table to control the fuel supply.
  • the property change determination unit 204 determines that the first moving average value Tcc_now is less than the second moving average value Tcc_before ⁇ 0.97, for example, the fuel supply table selection unit 205 uses the low heating value.
  • a fuel supply table is selected to control fuel supply.
  • the high calorific value fuel supply table is a table used when the calorific value of the fuel is higher than before.
  • the fuel flow rate is controlled to 1.0 L / min and the water is controlled to 7 g / min on the assumption that the fuel utilization rate and S / C are constant.
  • the low calorific value fuel supply table is a table used when the calorific value of the fuel is lower than the conventional one.
  • the fuel flow rate is controlled to, for example, 1.5 L / min and water is 10.5 g / min, assuming that the fuel utilization rate and S / C are constant.
  • FIG. 7 is a flowchart illustrating an example of a diagnosis process performed by the control unit according to the modification.
  • step S31 when the fuel cell system 1 starts power generation, detection of the temperature of the off-gas combustion unit 6 is started (step S31). Next, based on the amount of change in the moving average value of the temperature of the off-gas combustion unit 6, it is determined whether or not the fuel cell system 1 is in the rated operation state (step S32).
  • step S32 when it is determined that the fuel cell system 1 is in the rated operation state, the diagnosis start condition is determined (step S33, step S34). In the determination of the diagnosis start condition, for example, the same determination as in FIG. 4 is made (steps S21 to S24). If it is determined that the diagnosis start condition is not satisfied, the processes from step S32 to step S34 are repeated.
  • step S36 if the first moving average value Tcc_now is within the threshold value range, it is determined that there is no change in the fuel properties, and after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends ( Step S41). On the other hand, when the first moving average value Tcc_now is outside the threshold range in step S36, the magnitude of the first moving average value Tcc_now and the second moving average value Tcc_before is determined (step S37).
  • step S37 when the first moving average value Tcc_now is larger than the second moving average value Tcc_before, it is determined that the fuel property has changed and the heat value of the fuel is higher than the conventional value, and the high heat value is high.
  • the fuel supply is controlled based on the fuel supply table (step S38).
  • the first moving average value Tcc_now is smaller than the second moving average value Tcc_before, it is determined that the fuel property changes and the heat value of the fuel is lower than that of the conventional fuel, and the fuel for the low heat value
  • the supply of fuel is controlled based on the supply table (step S39).
  • the second moving average value Tcc_before is replaced with the first moving average value Tcc_now (step S40). Then, after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends (step S41).
  • the moving average value of the temperature of the off-gas combustion unit 6 has changed in the rated operation state where the sweep current of the cell stack 5 is constant. If it is determined that the fuel properties have changed. Therefore, compared with the conventional method of measuring a plurality of factors relating to the fuel property, the configuration necessary for determining whether or not the property of the fuel has changed can be simplified.
  • FIG. 8 is a diagram showing the relationship between the fuel properties and the cell stack output according to the modification.
  • heat amount of a fuel becomes lower than before is illustrated.
  • the temperature of the off-gas combustion unit 6 decreases when the fuel properties change and the amount of heat decreases.
  • the control unit 21 detects a change in the fuel property and the fuel supply table is changed, the decrease in the heat quantity of the fuel is compensated by the increase in the flow rate, and the temperature of the off-gas combustion unit 6 becomes the property of the fuel. It recovers to the same value as before the change.

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Abstract

In the fuel cell system (1), instead of directly measuring the state of fuel, the state of fuel is deemed to have changed if there is a change in the moving average of voltage outputted from the cell stack (5) in a rated operating state in which the sweep current of the cell stack (5) is constant. Therefore, it is possible to simplify the structure required to assess the existence of a change in the state of fuel, compared with conventional methods which measure a plurality of factors pertaining to the state of fuel.

Description

燃料電池システムFuel cell system
　本発明は、燃料電池システムに関する。 The present invention relates to a fuel cell system.
　逆潮流可能なサイト又は電力需要の大きなサイトにおいて、燃料電池システムは、セルスタックに供給される燃料の性状が一定であるものとして構築することができる。そのため、燃料の性状が変動するような環境に燃料電池システムを設置すると、システム内の熱バランスの悪化やセルスタックの劣化の進行を引き起こすおそれがあった。 In a site where reverse power flow is possible or a site where power demand is large, the fuel cell system can be constructed assuming that the properties of the fuel supplied to the cell stack are constant. For this reason, when the fuel cell system is installed in an environment in which the properties of the fuel fluctuate, there is a risk of causing deterioration of the heat balance in the system and progress of deterioration of the cell stack.
　このような問題に対し、例えば特許文献１に記載の燃料電池システムでは、燃料の性状及び流量を計測する燃料性状計測手段を燃料供給部に設け、計測結果に基づいて水蒸気供給量や燃料供給量といった各種のパラメータを制御している。 For such a problem, for example, in the fuel cell system described in Patent Document 1, fuel property measuring means for measuring the property and flow rate of the fuel is provided in the fuel supply unit, and the water vapor supply amount and the fuel supply amount are based on the measurement results. Various parameters such as are controlled.
特開２００６－４９０５６号公報JP 2006-49056 A
　しかしながら、上述のような従来の燃料性状計測手段は、実際には燃料の組成・発熱量・流量といった複数の因子を計測する構成を要する。したがって、燃料電池システムの構成の複雑化を招いてしまうおそれがある。 However, the conventional fuel property measuring means as described above actually requires a configuration for measuring a plurality of factors such as fuel composition, calorific value, and flow rate. Therefore, the configuration of the fuel cell system may be complicated.
　本発明は、上記課題の解決のためになされたものであり、簡単な構成で燃料の性状変化を検出できる燃料電池システムを提供することを目的とする。 The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel cell system capable of detecting a change in fuel properties with a simple configuration.
　上記課題の解決のため、本発明の一側面に係る燃料電池システムは、水素を含有する燃料を用いて水素含有ガスを発生させる水素発生部と、水素含有ガスを用いて発電を行うセルスタックと、を備える燃料電池システムであって、セルスタックから出力される電圧を検出する電圧検出部と、当該燃料電池システムが定格運転状態であるか否かを判断する運転状態判断部と、運転状態判断部によって燃料電池システムが定格運転状態であると判断された場合に、電圧検出部によって検出された電圧の現時点の第１移動平均値と、現時点より一定時間前の第２移動平均値とを算出し、第１移動平均値と第２移動平均値との比較に基づいて燃料の性状変化の有無を判断する性状変化判断部と、を備える。 In order to solve the above problems, a fuel cell system according to one aspect of the present invention includes a hydrogen generation unit that generates a hydrogen-containing gas using a fuel containing hydrogen, a cell stack that generates power using the hydrogen-containing gas, and A voltage detection unit that detects a voltage output from the cell stack, an operation state determination unit that determines whether or not the fuel cell system is in a rated operation state, and an operation state determination When the unit determines that the fuel cell system is in the rated operation state, the first moving average value of the voltage detected by the voltage detecting unit and the second moving average value of a certain time before the current time are calculated. And a property change determination unit that determines whether there is a change in the property of the fuel based on a comparison between the first moving average value and the second moving average value.
　この燃料電池システムでは、燃料の性状を直接測定する代わりに、セルスタックの掃引電流が一定となる定格運転状態において、セルスタックから出力される電圧の移動平均値の変化があった場合に、燃料の性状が変化したと判断する。したがって、燃料の性状に関する複数の因子を計測する従来の手法に比べて、燃料の性状変化の有無を判断するために必要な構成を簡単化できる。 In this fuel cell system, instead of directly measuring the properties of the fuel, if there is a change in the moving average value of the voltage output from the cell stack in the rated operating state where the sweep current of the cell stack is constant, the fuel cell system Judgment that the property of has changed. Therefore, compared with the conventional method of measuring a plurality of factors relating to the fuel property, the configuration necessary for determining whether or not the property of the fuel has changed can be simplified.
　また、本発明の他の側面に係る燃料電池システムは、水素を含有する燃料を用いて水素含有ガスを発生させる水素発生部と、水素含有ガスを用いて発電を行うセルスタックと、セルスタックから供給されるオフガスを燃焼させる燃焼部と、を備える燃料電池システムであって、燃焼部の温度を検出する温度検出部と、当該燃料電池システムが定格運転状態であるか否かを判断する運転状態判断部と、運転状態判断部によって燃料電池システムが定格運転状態であると判断された場合に、温度検出部によって検出された温度の現時点の第１移動平均値と、現時点より一定時間前の第２移動平均値とを算出し、第１移動平均値と第２移動平均値との比較に基づいて燃料の性状変化の有無を判断する性状変化判断部と、を備える。 A fuel cell system according to another aspect of the present invention includes a hydrogen generation unit that generates a hydrogen-containing gas using a hydrogen-containing fuel, a cell stack that generates power using the hydrogen-containing gas, and a cell stack. A fuel cell system for combusting supplied off-gas, a temperature detection unit for detecting the temperature of the combustion unit, and an operation state for determining whether or not the fuel cell system is in a rated operation state When the determination unit and the operation state determination unit determine that the fuel cell system is in the rated operation state, the current first moving average value of the temperature detected by the temperature detection unit and the first predetermined time before the current time A property change determining unit that calculates a two-moving average value and determines whether there is a change in the property of the fuel based on a comparison between the first moving average value and the second moving average value.
　この燃料電池システムでは、燃料の性状を直接測定する代わりに、セルスタックの掃引電流が一定となる定格運転状態において、温度検出部で検出される燃焼部の温度の移動平均値の変化があった場合に、燃料の性状が変化したと判断する。したがって、燃料の性状に関する複数の因子を計測する従来の手法に比べて、燃料の性状変化の有無を判断するために必要な構成を簡単化できる。 In this fuel cell system, instead of directly measuring the fuel properties, there was a change in the moving average value of the temperature of the combustion part detected by the temperature detection part in the rated operation state where the sweep current of the cell stack is constant. In this case, it is determined that the property of the fuel has changed. Therefore, compared with the conventional method of measuring a plurality of factors relating to the fuel property, the configuration necessary for determining whether or not the property of the fuel has changed can be simplified.
　この燃料電池システムによれば、簡単な構成で燃料の性状変化を検出できる。 This fuel cell system can detect changes in fuel properties with a simple configuration.
本発明に係る燃料電池システムの一実施形態を示す図である。1 is a diagram showing an embodiment of a fuel cell system according to the present invention. 制御部の機能的な構成要素を示す図である。It is a figure which shows the functional component of a control part. 制御部による診断処理の一例を示すフローチャートである。It is a flowchart which shows an example of the diagnostic process by a control part. 診断開始条件の判断の一例を示すフローチャートである。It is a flowchart which shows an example of judgment of diagnosis start conditions. 燃料の性状とセルスタックの出力との関係を示す図である。It is a figure which shows the relationship between the property of a fuel, and the output of a cell stack. 変形例に係る制御部の機能的な構成要素を示す図である。It is a figure which shows the functional component of the control part which concerns on a modification. 変形例に係る制御部による診断処理の一例を示すフローチャートである。It is a flowchart which shows an example of the diagnostic process by the control part which concerns on a modification. 変形例に係る燃料の性状とセルスタックの出力との関係を示す図である。It is a figure which shows the relationship between the property of the fuel which concerns on a modification, and the output of a cell stack.
　以下、図面を参照しながら、本発明に係る燃料電池システムの好適な実施形態について詳細に説明する。なお、各図において同一又は相当部分には同一符号を付し、重複する説明を省略する。 Hereinafter, preferred embodiments of a fuel cell system according to the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.
　図１に示されるように、燃料電池システム１は、脱硫部２と、水気化部３と、水素発生部４と、セルスタック５と、オフガス燃焼部６と、水素含有燃料供給部７と、水供給部８と、酸化剤供給部９と、パワーコンディショナー１０と、制御部１１と、を備えている。燃料電池システム１は、水素含有燃料及び酸化剤を用いて、セルスタック５にて発電を行う。燃料電池システム１におけるセルスタック５の種類は特に限定されず、例えば、固体高分子形燃料電池（ＰＥＦＣ：Polymer　Electrolyte　Fuel　Cell）、固体酸化物形燃料電池（ＳＯＦＣ：Solid　Oxide　Fuel　Cell）、リン酸形燃料電池（ＰＡＦＣ：Phosphoric　Acid　Fuel　Cell）、溶融炭酸塩形燃料電池（ＭＣＦＣ：Molten　Carbonate　Fuel　Cell）、及び、その他の種類を採用することができる。なお、セルスタック５の種類、水素含有燃料の種類、及び改質方式等に応じて、図１に示す構成要素を適宜省略してもよい。 As shown in FIG. 1, the fuel cell system 1 includes a desulfurization unit 2, a water vaporization unit 3, a hydrogen generation unit 4, a cell stack 5, an off-gas combustion unit 6, a hydrogen-containing fuel supply unit 7, The water supply part 8, the oxidizing agent supply part 9, the power conditioner 10, and the control part 11 are provided. The fuel cell system 1 generates power in the cell stack 5 using a hydrogen-containing fuel and an oxidant. The type of the cell stack 5 in the fuel cell system 1 is not particularly limited, and examples thereof include a polymer electrolyte fuel cell (PEFC), a solid oxide fuel cell (SOFC), and phosphoric acid. A fuel cell (PAFC: Phosphoric Acid Fuel Cell), a molten carbonate fuel cell (MCFC: Molten Carbonate Fuel Cell), and other types can be employed. 1 may be appropriately omitted depending on the type of cell stack 5, the type of hydrogen-containing fuel, the reforming method, and the like.
　水素含有燃料として、例えば、炭化水素系燃料が用いられる。炭化水素系燃料として、分子中に炭素と水素とを含む化合物（酸素等、他の元素を含んでいてもよい）若しくはそれらの混合物が用いられる。炭化水素系燃料として、例えば、炭化水素類、アルコール類、エーテル類、バイオ燃料が挙げられ、これらの炭化水素系燃料は従来の石油・石炭等の化石燃料由来のもの、合成ガス等の合成系燃料由来のもの、バイオマス由来のものを適宜用いることができる。具体的には、炭化水素類として、メタン、エタン、プロパン、ブタン、天然ガス、ＬＰＧ（液化石油ガス）、都市ガス、タウンガス、ガソリン、ナフサ、灯油、軽油が挙げられる。アルコール類として、メタノール、エタノールが挙げられる。エーテル類として、ジメチルエーテルが挙げられる。バイオ燃料として、バイオガス、バイオエタノール、バイオディーゼル、バイオジェットが挙げられる。 As the hydrogen-containing fuel, for example, a hydrocarbon fuel is used. As the hydrocarbon fuel, a compound containing carbon and hydrogen in the molecule (may contain other elements such as oxygen) or a mixture thereof is used. Examples of hydrocarbon fuels include hydrocarbons, alcohols, ethers, and biofuels. These hydrocarbon fuels are derived from conventional fossil fuels such as petroleum and coal, and synthetic systems such as synthesis gas. Those derived from fuel and those derived from biomass can be used as appropriate. Specific examples of hydrocarbons include methane, ethane, propane, butane, natural gas, LPG (liquefied petroleum gas), city gas, town gas, gasoline, naphtha, kerosene, and light oil. Examples of alcohols include methanol and ethanol. Examples of ethers include dimethyl ether. Examples of biofuels include biogas, bioethanol, biodiesel, and biojet.
　酸化剤として、例えば、空気、純酸素ガス（通常の除去手法で除去が困難な不純物を含んでもよい）、酸素富化空気が用いられる。 As the oxidizing agent, for example, air, pure oxygen gas (which may contain impurities that are difficult to remove by a normal removal method), or oxygen-enriched air is used.
　脱硫部２は、水素発生部４に供給される水素含有燃料の脱硫を行う。脱硫部２は、水素含有燃料に含有される硫黄化合物を除去するための脱硫触媒を有している。脱硫部２の脱硫方式として、例えば、硫黄化合物を吸着して除去する吸着脱硫方式や、硫黄化合物を水素と反応させて除去する水素化脱硫方式が採用される。脱硫部２は、脱硫した水素含有燃料を水素発生部４へ供給する。 The desulfurization unit 2 desulfurizes the hydrogen-containing fuel supplied to the hydrogen generation unit 4. The desulfurization part 2 has a desulfurization catalyst for removing sulfur compounds contained in the hydrogen-containing fuel. As the desulfurization method of the desulfurization unit 2, for example, an adsorptive desulfurization method that adsorbs and removes sulfur compounds and a hydrodesulfurization method that removes sulfur compounds by reacting with hydrogen are employed. The desulfurization unit 2 supplies the desulfurized hydrogen-containing fuel to the hydrogen generation unit 4.
　水気化部３は、水を加熱し気化させることによって、水素発生部４に供給される水蒸気を生成する。水気化部３における水の加熱は、例えば、水素発生部４の熱、オフガス燃焼部６の熱、あるいは排ガスの熱を回収する等、燃料電池システム１内で発生した熱を用いてもよい。また、別途ヒータ、バーナ等の他熱源を用いて水を加熱してもよい。なお、図１では、一例としてオフガス燃焼部６から水素発生部４へ供給される熱のみ記載されているが、これに限定されない。水気化部３は、生成した水蒸気を水素発生部４へ供給する。 The water vaporization unit 3 generates water vapor supplied to the hydrogen generation unit 4 by heating and vaporizing water. For the heating of the water in the water vaporization unit 3, for example, heat generated in the fuel cell system 1 such as recovering the heat of the hydrogen generation unit 4, the heat of the off-gas combustion unit 6, or the heat of the exhaust gas may be used. Moreover, you may heat water using other heat sources, such as a heater and a burner separately. In FIG. 1, only heat supplied from the off-gas combustion unit 6 to the hydrogen generation unit 4 is described as an example, but the present invention is not limited to this. The water vaporization unit 3 supplies the generated water vapor to the hydrogen generation unit 4.
　水素発生部４は、脱硫部２からの水素含有燃料を用いて水素リッチガスを発生させる。水素発生部４は、水素含有燃料を改質触媒によって改質する改質器を有している。水素発生部４での改質方式は、特に限定されず、例えば、水蒸気改質、部分酸化改質、自己熱改質、その他の改質方式を採用できる。なお、水素発生部４は、セルスタック５に要求される水素リッチガスの性状によって、改質触媒により改質する改質器の他に性状を調整するための構成を有する場合もある。例えば、セルスタック５のタイプが固体高分子形燃料電池（ＰＥＦＣ）やリン酸形燃料電池（ＰＡＦＣ）であった場合、水素発生部４は、水素リッチガス中の一酸化炭素を除去するための構成（例えば、シフト反応部、選択酸化反応部）を有する。水素発生部４は、水素リッチガスをセルスタック５のアノード１２へ供給する。 The hydrogen generation unit 4 generates a hydrogen rich gas using the hydrogen-containing fuel from the desulfurization unit 2. The hydrogen generator 4 has a reformer that reforms the hydrogen-containing fuel with a reforming catalyst. The reforming method in the hydrogen generating unit 4 is not particularly limited, and for example, steam reforming, partial oxidation reforming, autothermal reforming, and other reforming methods can be employed. The hydrogen generator 4 may have a configuration for adjusting the properties in addition to the reformer reformed by the reforming catalyst depending on the properties of the hydrogen rich gas required for the cell stack 5. For example, when the type of the cell stack 5 is a polymer electrolyte fuel cell (PEFC) or a phosphoric acid fuel cell (PAFC), the hydrogen generation unit 4 is configured to remove carbon monoxide in the hydrogen-rich gas. (For example, a shift reaction part and a selective oxidation reaction part). The hydrogen generation unit 4 supplies a hydrogen rich gas to the anode 12 of the cell stack 5.
　セルスタック５は、水素発生部４からの水素リッチガス及び酸化剤供給部９からの酸化剤を用いて発電を行う。セルスタック５は、水素リッチガスが供給されるアノード１２と、酸化剤が供給されるカソード１３と、アノード１２とカソード１３との間に配置される電解質１４と、を備えている。セルスタック５は、パワーコンディショナー１０を介して、電力を外部へ供給する。セルスタック５は、発電に用いられなかった水素リッチガス及び酸化剤をオフガスとして、オフガス燃焼部６へ供給する。なお、水素発生部４が備えている燃焼部（例えば、改質器を加熱する燃焼器など）をオフガス燃焼部６と共用してもよい。 The cell stack 5 generates power using the hydrogen rich gas from the hydrogen generation unit 4 and the oxidant from the oxidant supply unit 9. The cell stack 5 includes an anode 12 to which a hydrogen-rich gas is supplied, a cathode 13 to which an oxidant is supplied, and an electrolyte 14 disposed between the anode 12 and the cathode 13. The cell stack 5 supplies power to the outside via the power conditioner 10. The cell stack 5 supplies the hydrogen rich gas and the oxidant, which have not been used for power generation, to the off gas combustion unit 6 as off gas. Note that a combustion section (for example, a combustor that heats the reformer) provided in the hydrogen generation section 4 may be shared with the off-gas combustion section 6.
　オフガス燃焼部６は、セルスタック５から供給されるオフガスを燃焼させる。オフガス燃焼部６によって発生する熱は、水素発生部４へ供給され、水素発生部４での水素リッチガスの発生に用いられる。 The off gas combustion unit 6 burns off gas supplied from the cell stack 5. The heat generated by the off-gas combustion unit 6 is supplied to the hydrogen generation unit 4 and used for generation of a hydrogen rich gas in the hydrogen generation unit 4.
　水素含有燃料供給部７は、脱硫部２へ水素含有燃料を供給する。水供給部８は、水気化部３へ水を供給する。酸化剤供給部９は、セルスタック５のカソード１３へ酸化剤を供給する。水素含有燃料供給部７、水供給部８、及び酸化剤供給部９は、例えばポンプによって構成されており、制御部１１からの制御信号に基づいて駆動する。 The hydrogen-containing fuel supply unit 7 supplies hydrogen-containing fuel to the desulfurization unit 2. The water supply unit 8 supplies water to the water vaporization unit 3. The oxidant supply unit 9 supplies an oxidant to the cathode 13 of the cell stack 5. The hydrogen-containing fuel supply unit 7, the water supply unit 8, and the oxidant supply unit 9 are configured by a pump, for example, and are driven based on a control signal from the control unit 11.
　パワーコンディショナー１０は、セルスタック５からの電力を、外部での電力使用状態に合わせて調整する。パワーコンディショナー１０は、例えば、電圧を変換する処理や、直流電力を交流電力へ変換する処理を行う。 The power conditioner 10 adjusts the power from the cell stack 5 according to the external power usage state. For example, the power conditioner 10 performs a process of converting a voltage and a process of converting DC power into AC power.
　制御部１１は、燃料電池システム１全体の制御処理を行う。制御部１１は、例えばＣＰＵ（Central　Processing　Unit）、ＲＯＭ（Read　Only　Memory）、ＲＡＭ（Random　Access　Memory）、及び入出力インターフェイスを含んで構成されたデバイスによって構成される。制御部１１は、水素含有燃料供給部７、水供給部８、酸化剤供給部９、パワーコンディショナー１０、その他、図示されないセンサや補機と電気的に接続されている。制御部１１は、燃料電池システム１内で発生する各種信号を取得すると共に、燃料電池システム１内の各機器へ制御信号を出力する。 The control unit 11 performs control processing for the entire fuel cell system 1. The control unit 11 is configured by a device including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an input / output interface, for example. The control unit 11 is electrically connected to a hydrogen-containing fuel supply unit 7, a water supply unit 8, an oxidant supply unit 9, a power conditioner 10, and other sensors and auxiliary equipment not shown. The control unit 11 acquires various signals generated in the fuel cell system 1 and outputs a control signal to each device in the fuel cell system 1.
　続いて、制御部１１が実行する制御について更に詳細に説明する。 Subsequently, the control executed by the control unit 11 will be described in more detail.
　制御部１１は、燃料電池システム１内の各機器へ制御信号を出力する部分であるが、これに加えて、水素含有燃料供給部７から供給される水素含有燃料の性状（熱量や組成など）の変化に起因する燃料電池システム１の出力の変化を診断する診断処理を実行する。 The control unit 11 is a part that outputs a control signal to each device in the fuel cell system 1, but in addition to this, the properties (heat amount, composition, etc.) of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7. Diagnosis processing for diagnosing a change in the output of the fuel cell system 1 due to the change in the value is executed.
　この診断処理に関し、制御部１１は、図２に示すように、機能的な構成要素として、診断開始条件判断部１０１と、運転状態判断部１０２と、電圧検出部１０３と、性状変化判断部１０４と、燃料供給テーブル選択部１０５とを備えている。 As shown in FIG. 2, the control unit 11 includes a diagnosis start condition determination unit 101, an operation state determination unit 102, a voltage detection unit 103, and a property change determination unit 104 as functional components. And a fuel supply table selection unit 105.
　診断開始条件判断部１０１は、診断処理の実行を開始するか否かを判断する部分である。診断開始条件は、種々の条件を適用し得るが、例えば燃料電池システム１が発電を開始してから所定時間が経過したか否か、或いは燃料電池システム１に接続される貯湯槽（不図示）の残量が少なく、温水需要が生じていること（燃料電池システム１が熱回収をしている状態にあること）などが挙げられる。発電を開始してからの所定時間は、例えば１０００時間に設定される。 The diagnosis start condition determination unit 101 is a part that determines whether or not to start execution of diagnosis processing. Various conditions can be applied as the diagnosis start condition. For example, whether or not a predetermined time has elapsed since the fuel cell system 1 started power generation, or a hot water tank (not shown) connected to the fuel cell system 1 The remaining amount of water is small and there is a demand for hot water (the fuel cell system 1 is in a state of recovering heat). The predetermined time after starting the power generation is set to 1000 hours, for example.
　運転状態判断部１０２は、燃料電池システム１が定格運転状態であるか否かを判断する部分である。定格運転状態とは、セルスタック５で発電される電力が仕様上最大の電力となるような運転状態であり、電圧・電流が安定した動作をする状態である。運転状態判断部１０２は、例えばセルスタック５から出力される電圧の移動平均値の変化が一定時間（例えば１５分）にわたって閾値以下であった場合に、燃料電池システム１が定格運転状態であると判断する。 The operation state determination unit 102 is a part that determines whether or not the fuel cell system 1 is in a rated operation state. The rated operation state is an operation state in which the power generated by the cell stack 5 is the maximum power in the specification, and is a state in which the voltage / current operates stably. The operation state determination unit 102 determines that the fuel cell system 1 is in the rated operation state when, for example, the change in the moving average value of the voltage output from the cell stack 5 is equal to or less than the threshold value for a certain time (for example, 15 minutes). to decide.
　電圧検出部１０３は、セルスタック５からパワーコンディショナー１０に出力される電圧を検出する部分である。電圧検出部１０３は、燃料電池システム１が発電を行っている間、セルスタック５からパワーコンディショナー１０に出力される電圧を常時検出する。 The voltage detection unit 103 is a part that detects a voltage output from the cell stack 5 to the power conditioner 10. The voltage detector 103 constantly detects the voltage output from the cell stack 5 to the power conditioner 10 while the fuel cell system 1 is generating power.
　性状変化判断部１０４は、水素含有燃料供給部７から供給される水素含有燃料の性状変化の有無を判断する部分である。より具体的には、性状変化判断部１０４は、運転状態判断部１０２によって燃料電池システム１が定格運転状態であると判断された場合に、電圧検出部１０３によって検出された電圧の現時点の第１移動平均値Ｖｃｃ＿ｎｏｗと、現時点より一定時間前の第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅとを算出する。第１移動平均値Ｖｃｃ＿ｎｏｗ及び第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅは、例えば１５分間分の電圧の移動平均値とすればよい。また、第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅは、例えば第１移動平均値Ｖｃｃ＿ｎｏｗの１０時間前の移動平均値とすればよい。 The property change determination unit 104 is a part that determines whether or not the property of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 has changed. More specifically, the property change determination unit 104 determines the first current of the voltage detected by the voltage detection unit 103 when the operation state determination unit 102 determines that the fuel cell system 1 is in the rated operation state. The moving average value Vcc_now and the second moving average value Vcc_before for a certain time before the current time are calculated. The first moving average value Vcc_now and the second moving average value Vcc_before may be a moving average value of voltage for 15 minutes, for example. The second moving average value Vcc_before may be a moving average value 10 hours before the first moving average value Vcc_now, for example.
　第１移動平均値Ｖｃｃ＿ｎｏｗ及び第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅの算出の後、性状変化判断部１０４は、第１移動平均値Ｖｃｃ＿ｎｏｗ及び第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅを比較し、第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅに対する第１移動平均値Ｖｃｃ＿ｎｏｗの変化量が閾値を超えているか否かを判断する。この場合、上限閾値は、例えば第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅ×１．０３、下限閾値は、例えば第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅ×０．９７とすればよい。以上のような第１移動平均値Ｖｃｃ＿ｎｏｗ及び第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅの比較は、一定時間おきに実行してもよく、常時実行してもよい。 After calculating the first moving average value Vcc_now and the second moving average value Vcc_before, the property change determination unit 104 compares the first moving average value Vcc_now and the second moving average value Vcc_before, and compares the first moving average value Vcc_before with the second moving average value Vcc_before. It is determined whether or not the amount of change in the 1 moving average value Vcc_now exceeds a threshold value. In this case, the upper limit threshold value may be, for example, the second moving average value Vcc_before × 1.03, and the lower limit threshold value may be, for example, the second moving average value Vcc_before × 0.97. The comparison between the first moving average value Vcc_now and the second moving average value Vcc_before as described above may be executed at regular intervals or may be executed constantly.
　燃料供給テーブル選択部１０５は、性状変化判断部１０４における判断結果に基づいて、水素含有燃料供給部７から供給される水素含有燃料の供給テーブルを変更する部分である。燃料供給テーブル選択部１０５は、性状変化判断部１０４において、例えば第１移動平均値Ｖｃｃ＿ｎｏｗが第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅ×１．０３を超えていると判断された場合には、高発熱量用燃料供給テーブルを選択して燃料の供給を制御する。一方、燃料供給テーブル選択部１０５は、性状変化判断部１０４において、例えば第１移動平均値Ｖｃｃ＿ｎｏｗが第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅ×０．９７に満たないと判断された場合には、低発熱量用燃料供給テーブルを選択して燃料の供給を制御する。 The fuel supply table selection unit 105 is a part that changes the supply table of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 based on the determination result in the property change determination unit 104. When the property change determination unit 104 determines that the first moving average value Vcc_now exceeds the second moving average value Vcc_before × 1.03, for example, the fuel supply table selection unit 105 determines that the fuel for the high calorific value is high. Select the supply table to control the fuel supply. On the other hand, if the property change determining unit 104 determines that the first moving average value Vcc_now is less than the second moving average value Vcc_before × 0.97, for example, the fuel supply table selecting unit 105 uses the low heating value. A fuel supply table is selected to control fuel supply.
　高発熱量用燃料供給テーブルは、燃料の発熱量が従来よりも高くなっている場合に用いるテーブルである。高発熱量用燃料供給テーブルを用いる場合、燃料利用率及びＳ／Ｃが一定であること前提として、例えば燃料流量１．０Ｌ／ｍｉｎ、水７ｇ／ｍｉｎに制御される。低発熱量用燃料供給テーブルは、燃料の発熱量が従来よりも低くなっている場合に用いるテーブルである。低発熱量用燃料供給テーブルを用いる場合、燃料利用率及びＳ／Ｃが一定であること前提として、例えば燃料流量１．５Ｌ／ｍｉｎ、水１０．５ｇ／ｍｉｎに制御される。 The high calorific value fuel supply table is a table used when the calorific value of the fuel is higher than before. In the case of using the high calorific value fuel supply table, for example, the fuel flow rate is controlled to 1.0 L / min and the water is controlled to 7 g / min on the assumption that the fuel utilization rate and S / C are constant. The low calorific value fuel supply table is a table used when the calorific value of the fuel is lower than the conventional one. When using the fuel supply table for a low calorific value, the fuel flow rate is controlled to, for example, 1.5 L / min and water is 10.5 g / min, assuming that the fuel utilization rate and S / C are constant.
　次に、制御部１１の動作について説明する。図３は、制御部による診断処理の一例を示すフローチャートである。 Next, the operation of the control unit 11 will be described. FIG. 3 is a flowchart illustrating an example of diagnosis processing by the control unit.
　まず、燃料電池システム１が発電を開始すると、セルスタック５から出力される電圧の検出が開始される（ステップＳ０１）。次に、セルスタック５から出力される電圧の移動平均値の変化量に基づいて、燃料電池システム１が定格運転状態であるか否かが判断される（ステップＳ０２）。 First, when the fuel cell system 1 starts power generation, detection of the voltage output from the cell stack 5 is started (step S01). Next, based on the amount of change in the moving average value of the voltage output from the cell stack 5, it is determined whether or not the fuel cell system 1 is in the rated operation state (step S02).
　ステップＳ０２において、燃料電池システム１が定格運転状態であると判断された場合、診断開始条件の判断がなされる（ステップＳ０３，ステップＳ０４）。診断開始条件の判断では、例えば図４に示すように、まず、発電開始から所定時間が経過したか否かが判断される（ステップＳ２１）。次いで、温水需要が大きいか否かが判断され（ステップＳ２２）、ステップＳ２１，２２をいずれも満たす場合には、診断開始条件を満たすと判断される（ステップＳ２３）。また、ステップＳ２１，Ｓ２２のいずれかを満たさない場合には、診断開始条件を満たさないと判断される（ステップＳ２４）。診断開始条件を満たさないと判断された場合、ステップＳ０２～ステップＳ０４までの処理が繰り返し行われる。 In step S02, when it is determined that the fuel cell system 1 is in the rated operation state, the diagnosis start condition is determined (step S03, step S04). In the determination of the diagnosis start condition, for example, as shown in FIG. 4, it is first determined whether or not a predetermined time has elapsed since the start of power generation (step S21). Next, it is determined whether or not the demand for hot water is large (step S22). If both the steps S21 and S22 are satisfied, it is determined that the diagnosis start condition is satisfied (step S23). If either of steps S21 and S22 is not satisfied, it is determined that the diagnosis start condition is not satisfied (step S24). If it is determined that the diagnosis start condition is not satisfied, the processes from step S02 to step S04 are repeated.
　診断開始条件を満たすと判断された場合、図３に示すように、電圧検出部１０３によって検出された電圧の現時点の第１移動平均値Ｖｃｃ＿ｎｏｗと、現時点より一定時間前の第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅとの算出が行われる（ステップＳ０５）。次に、第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅ×０．９７＜第１移動平均値Ｖｃｃ＿ｎｏｗ＜第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅ×１．０３を満たすか否かが判断される（ステップＳ０６）。 When it is determined that the diagnosis start condition is satisfied, as shown in FIG. 3, the current first moving average value Vcc_now of the voltage detected by the voltage detection unit 103 and the second moving average value Vcc_before for a certain time before the current time. Is calculated (step S05). Next, it is determined whether or not the second moving average value Vcc_before × 0.97 <the first moving average value Vcc_now <the second moving average value Vcc_before × 1.03 is satisfied (step S06).
　ステップＳ０６において、第１移動平均値Ｖｃｃ＿ｎｏｗが閾値の範囲内であった場合には、燃料の性状に変化はないと判断され、診断開始から所定の時間が経過した後、診断処理が終了する（ステップＳ１１）。一方、ステップＳ０６において、第１移動平均値Ｖｃｃ＿ｎｏｗが閾値の範囲外であった場合には、第１移動平均値Ｖｃｃ＿ｎｏｗと第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅとの大小が判断される（ステップＳ０７）。 In step S06, if the first moving average value Vcc_now is within the threshold value range, it is determined that there is no change in the properties of the fuel, and after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends ( Step S11). On the other hand, if the first moving average value Vcc_now is outside the threshold value range in step S06, the magnitude of the first moving average value Vcc_now and the second moving average value Vcc_before is determined (step S07).
　ステップＳ０７において、第１移動平均値Ｖｃｃ＿ｎｏｗが第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅより大きい場合には、燃料の性状が変化して、燃料の発熱量が従来よりも高くなっていると判断され、高発熱量用燃料供給テーブルに基づいて燃料の供給が制御される（ステップＳ０８）。一方、第１移動平均値Ｖｃｃ＿ｎｏｗが第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅより小さい場合には、燃料の性状が変化して、燃料の発熱量が従来よりも低くなっていると判断され、低発熱量用燃料供給テーブルに基づいて燃料の供給が制御される（ステップＳ０９）。いずれの場合も、燃料供給テーブルの変更が行われた場合には、第２移動平均値Ｖｃｃ＿ｂｅｆｏｒｅが第１移動平均値Ｖｃｃ＿ｎｏｗに置換される（ステップＳ１０）。そして、診断開始から所定の時間が経過した後、診断処理が終了する（ステップＳ１１）。 In step S07, when the first moving average value Vcc_now is larger than the second moving average value Vcc_before, it is determined that the property of the fuel has changed and the heat value of the fuel is higher than the conventional value, and the high heat value is high. The fuel supply is controlled based on the fuel supply table (step S08). On the other hand, when the first moving average value Vcc_now is smaller than the second moving average value Vcc_before, it is determined that the fuel property has changed and the heat value of the fuel is lower than that of the conventional fuel. The supply of fuel is controlled based on the supply table (step S09). In any case, when the fuel supply table is changed, the second moving average value Vcc_before is replaced with the first moving average value Vcc_now (step S10). Then, after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends (step S11).
　以上説明したように、燃料電池システム１では、燃料の性状を直接測定する代わりに、セルスタック５の掃引電流が一定となる定格運転状態において、セルスタック５から出力される電圧の移動平均値に変化があった場合に、燃料の性状が変化したと判断する。したがって、燃料の性状に関する複数の因子を計測する従来の手法に比べて、燃料の性状変化の有無を判断するために必要な構成を簡単化できる。 As described above, in the fuel cell system 1, instead of directly measuring the properties of the fuel, in the rated operation state where the sweep current of the cell stack 5 is constant, the moving average value of the voltage output from the cell stack 5 is obtained. If there is a change, it is determined that the fuel properties have changed. Therefore, compared with the conventional method of measuring a plurality of factors relating to the fuel property, the configuration necessary for determining whether or not the property of the fuel has changed can be simplified.
　図５は、燃料の性状とセルスタックの出力との関係を示す図である。同図では、燃料の熱量が従来よりも低くなる場合を例示している。掃引電流が一定となる定格運転状態において、燃料の性状が変化して熱量が低くなると、セルスタック５から出力される電圧が低下する。これに対し、制御部１１が燃料の性状の変化を検出し、燃料供給テーブルが変更されると、燃料の熱量の減少が流量の増加によって補われ、セルスタック５から出力される電圧が燃料の性状の変化前と同等の値まで回復する。 FIG. 5 is a diagram showing the relationship between fuel properties and cell stack output. In the figure, the case where the calorie | heat amount of a fuel becomes lower than before is illustrated. In the rated operation state where the sweep current is constant, when the fuel property changes and the amount of heat decreases, the voltage output from the cell stack 5 decreases. On the other hand, when the control unit 11 detects a change in the properties of the fuel and the fuel supply table is changed, the decrease in the heat quantity of the fuel is compensated by the increase in the flow rate, and the voltage output from the cell stack 5 It recovers to the same value as before the change of properties.
　次に、本発明の変形例について説明する。変形例は、セルスタック５から出力される電圧の検出に代えて、オフガス燃焼部６の温度の検出によって燃料の性状の変化を診断する点で上述した実施形態と異なっている。 Next, a modified example of the present invention will be described. The modified example is different from the above-described embodiment in that the change in the property of the fuel is diagnosed by detecting the temperature of the off-gas combustion unit 6 instead of detecting the voltage output from the cell stack 5.
　診断処理に関し、変形例における制御部２１は、図６に示すように、機能的な構成要素として、診断開始条件判断部２０１と、運転状態判断部２０２と、温度検出部２０３と、性状変化判断部２０４と、燃料供給テーブル選択部２０５とを備えている。診断開始条件判断部２０１については、上述した診断開始条件判断部１０１と同様であるため、説明を省略する。 As shown in FIG. 6, the control unit 21 in the modification example includes, as functional components, a diagnosis start condition determination unit 201, an operation state determination unit 202, a temperature detection unit 203, and a property change determination as illustrated in FIG. 6. Unit 204 and a fuel supply table selection unit 205. The diagnosis start condition determination unit 201 is the same as the diagnosis start condition determination unit 101 described above, and a description thereof will be omitted.
　運転状態判断部２０２は、燃料電池システム１が定格運転状態であるか否かを判断する部分である。運転状態判断部２０２は、例えばオフガス燃焼部６の温度の移動平均値の変化が一定時間（例えば１５分）にわたって閾値以下であった場合に、燃料電池システム１が定格運転状態であると判断する。 The operation state determination unit 202 is a part that determines whether or not the fuel cell system 1 is in a rated operation state. The operation state determination unit 202 determines that the fuel cell system 1 is in the rated operation state when, for example, the change in the moving average value of the temperature of the off-gas combustion unit 6 is equal to or less than the threshold value for a certain time (for example, 15 minutes). .
　温度検出部２０３は、オフガス燃焼部６の温度を検出する部分である。温度検出部２０３は、燃料電池システム１が発電を行っている間、オフガス燃焼部６の温度を常時検出する。 The temperature detection unit 203 is a part that detects the temperature of the off-gas combustion unit 6. The temperature detection unit 203 always detects the temperature of the off-gas combustion unit 6 while the fuel cell system 1 is generating power.
　性状変化判断部２０４は、水素含有燃料供給部７から供給される水素含有燃料の性状変化の有無を判断する部分である。より具体的には、性状変化判断部２０４は、運転状態判断部２０２によって燃料電池システム１が定格運転状態であると判断された場合に、温度検出部２０３によって検出されたオフガス燃焼部６の温度の現時点の第１移動平均値Ｔｃｃ＿ｎｏｗと、現時点より一定時間前の第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅとを算出する。第１移動平均値Ｔｃｃ＿ｎｏｗ及び第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅは、例えば１５分間分の温度の移動平均値とすればよい。また、第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅは、例えば第１移動平均値Ｔｃｃ＿ｎｏｗの１０時間前の移動平均値とすればよい。 The property change determination unit 204 is a part that determines whether or not the property of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 has changed. More specifically, the property change determination unit 204 determines the temperature of the off-gas combustion unit 6 detected by the temperature detection unit 203 when the operation state determination unit 202 determines that the fuel cell system 1 is in the rated operation state. The first moving average value Tcc_now at the present time and the second moving average value Tcc_before for a certain time before the current time are calculated. The first moving average value Tcc_now and the second moving average value Tcc_before may be, for example, moving average values of temperatures for 15 minutes. The second moving average value Tcc_before may be a moving average value 10 hours before the first moving average value Tcc_now, for example.
　第１移動平均値Ｔｃｃ＿ｎｏｗ及び第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅの算出の後、性状変化判断部２０４は、第１移動平均値Ｔｃｃ＿ｎｏｗ及び第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅを比較し、第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅに対する第１移動平均値Ｔｃｃ＿ｎｏｗの変化量が閾値を超えているか否かを判断する。この場合、上限閾値は、例えば第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅ×１．０３、下限閾値は、例えば第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅ×０．９７とすればよい。以上のような第１移動平均値Ｔｃｃ＿ｎｏｗ及び第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅの比較は、一定時間おきに実行してもよく、常時実行してもよい。 After calculating the first moving average value Tcc_now and the second moving average value Tcc_before, the property change determining unit 204 compares the first moving average value Tcc_now and the second moving average value Tcc_before, and compares the first moving average value Tcc_before with the second moving average value Tcc_before. It is determined whether or not the amount of change in the 1 moving average value Tcc_now exceeds a threshold value. In this case, the upper limit threshold value may be, for example, the second moving average value Tcc_before × 1.03, and the lower limit threshold value may be, for example, the second moving average value Tcc_before × 0.97. The comparison between the first moving average value Tcc_now and the second moving average value Tcc_before as described above may be executed at regular intervals or may be executed constantly.
　燃料供給テーブル選択部２０５は、性状変化判断部２０４における判断結果に基づいて、水素含有燃料供給部７から供給される水素含有燃料の供給テーブルを変更する部分である。燃料供給テーブル選択部２０５は、性状変化判断部２０４において、例えば第１移動平均値Ｔｃｃ＿ｎｏｗが第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅ×１．０３を超えていると判断された場合には、高発熱量用燃料供給テーブルを選択して燃料の供給を制御する。一方、燃料供給テーブル選択部２０５は、性状変化判断部２０４において、例えば第１移動平均値Ｔｃｃ＿ｎｏｗが第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅ×０．９７に満たないと判断された場合には、低発熱量用燃料供給テーブルを選択して燃料の供給を制御する。 The fuel supply table selection unit 205 is a part that changes the supply table of the hydrogen-containing fuel supplied from the hydrogen-containing fuel supply unit 7 based on the determination result in the property change determination unit 204. When the property change determination unit 204 determines that the first moving average value Tcc_now exceeds the second moving average value Tcc_before × 1.03, for example, the fuel supply table selection unit 205 has a high heating value fuel. Select the supply table to control the fuel supply. On the other hand, when the property change determination unit 204 determines that the first moving average value Tcc_now is less than the second moving average value Tcc_before × 0.97, for example, the fuel supply table selection unit 205 uses the low heating value. A fuel supply table is selected to control fuel supply.
　高発熱量用燃料供給テーブルは、燃料の発熱量が従来よりも高くなっている場合に用いるテーブルである。高発熱量用燃料供給テーブルを用いる場合、燃料利用率及びＳ／Ｃが一定であること前提として、例えば燃料流量１．０Ｌ／ｍｉｎ、水７ｇ／ｍｉｎに制御される。低発熱量用燃料供給テーブルは、燃料の発熱量が従来よりも低くなっている場合に用いるテーブルである。低発熱量用燃料供給テーブルを用いる場合、燃料利用率及びＳ／Ｃが一定であること前提として、例えば燃料流量１．５Ｌ／ｍｉｎ、水１０．５ｇ／ｍｉｎに制御される。 The high calorific value fuel supply table is a table used when the calorific value of the fuel is higher than before. In the case of using the high calorific value fuel supply table, for example, the fuel flow rate is controlled to 1.0 L / min and the water is controlled to 7 g / min on the assumption that the fuel utilization rate and S / C are constant. The low calorific value fuel supply table is a table used when the calorific value of the fuel is lower than the conventional one. When using the fuel supply table for a low calorific value, the fuel flow rate is controlled to, for example, 1.5 L / min and water is 10.5 g / min, assuming that the fuel utilization rate and S / C are constant.
　次に、制御部２１の動作について説明する。図７は、変形例に係る制御部による診断処理の一例を示すフローチャートである。 Next, the operation of the control unit 21 will be described. FIG. 7 is a flowchart illustrating an example of a diagnosis process performed by the control unit according to the modification.
　まず、燃料電池システム１が発電を開始すると、オフガス燃焼部６の温度の検出が開始される（ステップＳ３１）。次に、オフガス燃焼部６の温度の移動平均値の変化量に基づいて、燃料電池システム１が定格運転状態であるか否かが判断される（ステップＳ３２）。 First, when the fuel cell system 1 starts power generation, detection of the temperature of the off-gas combustion unit 6 is started (step S31). Next, based on the amount of change in the moving average value of the temperature of the off-gas combustion unit 6, it is determined whether or not the fuel cell system 1 is in the rated operation state (step S32).
　ステップＳ３２において、燃料電池システム１が定格運転状態であると判断された場合、診断開始条件の判断がなされる（ステップＳ３３，ステップＳ３４）。診断開始条件の判断では、例えば図４と同様の判断がなされる（ステップＳ２１～Ｓ２４）。診断開始条件を満たさないと判断された場合、ステップＳ３２～ステップＳ３４までの処理が繰り返し行われる。 In step S32, when it is determined that the fuel cell system 1 is in the rated operation state, the diagnosis start condition is determined (step S33, step S34). In the determination of the diagnosis start condition, for example, the same determination as in FIG. 4 is made (steps S21 to S24). If it is determined that the diagnosis start condition is not satisfied, the processes from step S32 to step S34 are repeated.
　診断開始条件を満たすと判断された場合、図７に示すように、温度検出部２０３によって検出された温度の現時点の第１移動平均値Ｔｃｃ＿ｎｏｗと、現時点より一定時間前の第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅとの算出が行われる（ステップＳ３５）。次に、第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅ×０．９７＜第１移動平均値Ｔｃｃ＿ｎｏｗ＜第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅ×１．０３を満たすか否かが判断される（ステップＳ３６）。 When it is determined that the diagnosis start condition is satisfied, as shown in FIG. 7, the current first moving average value Tcc_now of the temperature detected by the temperature detecting unit 203 and the second moving average value Tcc_before for a certain time before the current time. Is calculated (step S35). Next, it is determined whether or not the second moving average value Tcc_before × 0.97 <first moving average value Tcc_now <second moving average value Tcc_before × 1.03 is satisfied (step S36).
　ステップＳ３６において、第１移動平均値Ｔｃｃ＿ｎｏｗが閾値の範囲内であった場合には、燃料の性状に変化はないと判断され、診断開始から所定の時間が経過した後、診断処理が終了する（ステップＳ４１）。一方、ステップＳ３６において、第１移動平均値Ｔｃｃ＿ｎｏｗが閾値の範囲外であった場合には、第１移動平均値Ｔｃｃ＿ｎｏｗと第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅとの大小が判断される（ステップＳ３７）。 In step S36, if the first moving average value Tcc_now is within the threshold value range, it is determined that there is no change in the fuel properties, and after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends ( Step S41). On the other hand, when the first moving average value Tcc_now is outside the threshold range in step S36, the magnitude of the first moving average value Tcc_now and the second moving average value Tcc_before is determined (step S37).
　ステップＳ３７において、第１移動平均値Ｔｃｃ＿ｎｏｗが第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅより大きい場合には、燃料の性状が変化して、燃料の発熱量が従来よりも高くなっていると判断され、高発熱量用燃料供給テーブルに基づいて燃料の供給が制御される（ステップＳ３８）。一方、第１移動平均値Ｔｃｃ＿ｎｏｗが第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅより小さい場合には、燃料の性状が変化して、燃料の発熱量が従来よりも低くなっていると判断され、低発熱量用燃料供給テーブルに基づいて燃料の供給が制御される（ステップＳ３９）。いずれの場合も、燃料供給テーブルの変更が行われた場合には、第２移動平均値Ｔｃｃ＿ｂｅｆｏｒｅが第１移動平均値Ｔｃｃ＿ｎｏｗに置換される（ステップＳ４０）。そして、診断開始から所定の時間が経過した後、診断処理が終了する（ステップＳ４１）。 In step S37, when the first moving average value Tcc_now is larger than the second moving average value Tcc_before, it is determined that the fuel property has changed and the heat value of the fuel is higher than the conventional value, and the high heat value is high. The fuel supply is controlled based on the fuel supply table (step S38). On the other hand, when the first moving average value Tcc_now is smaller than the second moving average value Tcc_before, it is determined that the fuel property changes and the heat value of the fuel is lower than that of the conventional fuel, and the fuel for the low heat value The supply of fuel is controlled based on the supply table (step S39). In any case, when the fuel supply table is changed, the second moving average value Tcc_before is replaced with the first moving average value Tcc_now (step S40). Then, after a predetermined time has elapsed from the start of diagnosis, the diagnosis process ends (step S41).
　以上説明したように、本変形例では、燃料の性状を直接測定する代わりに、セルスタック５の掃引電流が一定となる定格運転状態において、オフガス燃焼部６の温度の移動平均値に変化があった場合に、燃料の性状が変化したと判断する。したがって、燃料の性状に関する複数の因子を計測する従来の手法に比べて、燃料の性状変化の有無を判断するために必要な構成を簡単化できる。 As described above, in this modification, instead of directly measuring the fuel property, the moving average value of the temperature of the off-gas combustion unit 6 has changed in the rated operation state where the sweep current of the cell stack 5 is constant. If it is determined that the fuel properties have changed. Therefore, compared with the conventional method of measuring a plurality of factors relating to the fuel property, the configuration necessary for determining whether or not the property of the fuel has changed can be simplified.
　図８は、変形例に係る燃料の性状とセルスタックの出力との関係を示す図である。同図では、燃料の熱量が従来よりも低くなる場合を例示している。掃引電流が一定となる定格運転状態において、燃料の性状が変化して熱量が低くなると、オフガス燃焼部６の温度が低下する。これに対し、制御部２１が燃料の性状の変化を検出し、燃料供給テーブルが変更されると、燃料の熱量の減少が流量の増加によって補われ、オフガス燃焼部６の温度が燃料の性状の変化前と同等の値まで回復する。 FIG. 8 is a diagram showing the relationship between the fuel properties and the cell stack output according to the modification. In the figure, the case where the calorie | heat amount of a fuel becomes lower than before is illustrated. In the rated operating state where the sweep current is constant, the temperature of the off-gas combustion unit 6 decreases when the fuel properties change and the amount of heat decreases. On the other hand, when the control unit 21 detects a change in the fuel property and the fuel supply table is changed, the decrease in the heat quantity of the fuel is compensated by the increase in the flow rate, and the temperature of the off-gas combustion unit 6 becomes the property of the fuel. It recovers to the same value as before the change.
　１…燃料電池システム、４…水素発生部、５…セルスタック、６…オフガス燃焼部、１０２，２０２…運転状態判断部、１０３…電圧検出部、１０４，２０４…性状変化判断部、２０３…温度検出部。 DESCRIPTION OF SYMBOLS 1 ... Fuel cell system, 4 ... Hydrogen generation part, 5 ... Cell stack, 6 ... Off-gas combustion part, 102, 202 ... Operating condition judgment part, 103 ... Voltage detection part, 104, 204 ... Property change judgment part, 203 ... Temperature Detection unit.

Claims (2)

  1. 　水素を含有する燃料を用いて水素含有ガスを発生させる水素発生部と、
    　前記水素含有ガスを用いて発電を行うセルスタックと、を備える燃料電池システムであって、
    　前記セルスタックから出力される電圧を検出する電圧検出部と、
    　当該燃料電池システムが定格運転状態であるか否かを判断する運転状態判断部と、
    　前記運転状態判断部によって前記燃料電池システムが定格運転状態であると判断された場合に、前記電圧検出部によって検出された前記電圧の現時点の第１移動平均値と、前記現時点より一定時間前の第２移動平均値とを算出し、前記第１移動平均値と前記第２移動平均値との比較に基づいて前記燃料の性状変化の有無を判断する性状変化判断部と、を備える燃料電池システム。     A hydrogen generating section that generates a hydrogen-containing gas using a fuel containing hydrogen;
    A cell stack that generates power using the hydrogen-containing gas, and a fuel cell system comprising:
    A voltage detector for detecting a voltage output from the cell stack;
    An operation state determination unit for determining whether or not the fuel cell system is in a rated operation state;
    When the fuel cell system is determined to be in a rated operation state by the operation state determination unit, the current first moving average value of the voltage detected by the voltage detection unit and a certain time before the current time A fuel cell system comprising: a property change determining unit that calculates a second moving average value and determines whether there is a change in the property of the fuel based on a comparison between the first moving average value and the second moving average value .
  2. 　水素を含有する燃料を用いて水素含有ガスを発生させる水素発生部と、
    　前記水素含有ガスを用いて発電を行うセルスタックと、
    　前記セルスタックから供給されるオフガスを燃焼させる燃焼部と、を備える燃料電池システムであって、
    　前記燃焼部の温度を検出する温度検出部と、
    　当該燃料電池システムが定格運転状態であるか否かを判断する運転状態判断部と、
    　前記運転状態判断部によって前記燃料電池システムが定格運転状態であると判断された場合に、前記温度検出部によって検出された前記温度の現時点の第１移動平均値と、前記現時点より一定時間前の第２移動平均値とを算出し、前記第１移動平均値と前記第２移動平均値との比較に基づいて前記燃料の性状変化の有無を判断する性状変化判断部と、を備える燃料電池システム。     A hydrogen generating section that generates a hydrogen-containing gas using a fuel containing hydrogen;
    A cell stack for generating power using the hydrogen-containing gas;
    A fuel cell system comprising a combustion section for burning off-gas supplied from the cell stack,
    A temperature detection unit for detecting the temperature of the combustion unit;
    An operation state determination unit for determining whether or not the fuel cell system is in a rated operation state;
    When the operation state determination unit determines that the fuel cell system is in a rated operation state, a current first moving average value of the temperature detected by the temperature detection unit and a predetermined time before the current time A fuel cell system comprising: a property change determining unit that calculates a second moving average value and determines whether there is a change in the property of the fuel based on a comparison between the first moving average value and the second moving average value .
PCT/JP2011/080264 2010-12-28 2011-12-27 Fuel cell system WO2012091033A1 (en)

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