fuel cell system

Abstract

The present disclosure provides a fuel cell system that suppresses performance degradation even if impurities such as sulfur-based (sulfur or sulfide), bromine-based (bromine or bromide), chlorine-based (chlorine or chloride), ammonia-based (ammonia and its compounds (ammonium compounds)), volatile organic compounds, and metals are temporarily mixed into hydrogen or air. [Solution] A fuel cell system comprising a polymer electrolyte fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, a water quality meter that measures the quality of the water produced when the fuel cell unit generates electricity, and a control unit that controls the fuel cell unit based on the water quality measured by the water quality meter.

Description

[Technical Field]

[0001] The present disclosure relates to fuel cell systems. [Background technology]

[0002] Patent Document 1 discloses a method for operating a polymer electrolyte fuel cell, which includes a step of preventing the polymer electrolyte fuel cell from being in a cell performance deterioration region when the polymer electrolyte fuel cell is determined to be in the cell performance deterioration region. Patent Document 2 discloses an ion quantitative analysis method in which the fluorine ion concentration detected by ion chromatography from the anode and cathode discharge waters of a polymer electrolyte membrane fuel cell is used as an index of decomposition components of the polymer electrolyte membrane. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-127548 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-078226 Summary of the Invention [Problem to be solved by the invention]

[0004] The hydrogen or air supplied to a fuel cell may temporarily become contaminated with impurities such as sulfur-based (sulfur or sulfide), bromine-based (bromine or bromide), chlorine-based (chlorine or chloride), ammonia-based (ammonia and its compounds (ammonium compounds)), volatile organic compounds, metals, etc. If impurities such as sulfur-based (sulfur or sulfide), bromine-based (bromine or bromide), chlorine-based (chlorine or chloride), ammonia-based (ammonia and its compounds (ammonium compounds)), volatile organic compounds, metals, etc. become contaminated with hydrogen or air, the impurities may adhere to the catalyst in the fuel cell and inhibit the power generation reaction.

[0005] The present disclosure provides a fuel cell system that suppresses performance degradation even if impurities such as sulfur-based (sulfur or sulfide), bromine-based (bromine or bromide), chlorine-based (chlorine or chloride), ammonia-based (ammonia and its compounds (ammonium compounds)), volatile organic compounds, and metals are temporarily mixed into hydrogen or air. [Means for solving the problem]

[0006] The present disclosure provides a fuel cell system comprising a polymer electrolyte fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, a water quality meter that measures the quality of water produced when the fuel cell unit generates electricity, and a control unit that controls the fuel cell unit based on the water quality measured by the water quality meter. [Effects of the Invention]

[0007] According to the fuel cell system of the present disclosure, even if impurities such as sulfur-based (sulfur or sulfide), bromine-based (bromine or bromide), chlorine-based (chlorine or chloride), ammonia-based (ammonia and its compounds (ammonium compounds)), volatile organic compounds, metals, etc. are temporarily mixed into the hydrogen or air, degradation of performance can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing an outline of the configuration of a fuel cell system according to a first embodiment. [Figure 2] FIG. 2 is a flow chart illustrating the processing in the fuel cell system according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating the operation of the fuel cell system according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing an outline of the configuration of a fuel cell system according to the second embodiment. [Figure 5] FIG. 5 is a flow chart illustrating the processing in the fuel cell system according to the second embodiment. [Figure 6]FIG. 6 is a diagram illustrating the operation of the fuel cell system according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing an outline of the configuration of a fuel cell system according to the third embodiment. [Figure 8] FIG. 8 is a diagram showing an outline of the configuration of a fuel cell system according to a fourth embodiment. [Figure 9] FIG. 9 is a flow chart illustrating the processing in the fuel cell system according to the fourth embodiment. [Figure 10] FIG. 10 is a diagram illustrating the operation of the fuel cell system according to the fourth embodiment. [Figure 11] FIG. 11 is a diagram showing an outline of the configuration of a fuel cell system according to a fifth embodiment. [Figure 12] FIG. 12 is a diagram showing an outline of the configuration of a fuel cell system according to a sixth embodiment. [Figure 13] FIG. 13 is a diagram showing an outline of the configuration of a fuel cell system according to a seventh embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0010] In the description of the specification and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be designated by the same reference numerals to avoid redundant explanation. In addition, the scale of each part in the drawings may differ from the actual scale to facilitate understanding.

[0011] First Embodiment A fuel cell system according to a first embodiment will be described. The fuel cell system according to the first embodiment includes a polymer electrolyte fuel cell unit that generates electricity through a chemical reaction between hydrogen and oxygen, and a water quality meter that measures the quality of water produced when the fuel cell unit generates electricity. The fuel cell system according to the first embodiment also includes a control unit that controls the fuel cell unit based on the water quality measured by the water quality meter.

[0012] FIG. 1 is a diagram showing an outline of the configuration of a fuel cell system 1, which is an example of a fuel cell system according to a first embodiment.

[0013] The fuel cell system 1 is a fuel cell that uses fuel cells. The fuel cell system 1 is a chemical cell that converts chemical energy into electricity by reacting hydrogen with oxygen in the air as fuel. The fuel cell system 1 supplies an output Pout to an external load EX.

[0014] The fuel cell system 1 includes a fuel cell unit 10, a control unit 20, a power storage unit 30, a gas-liquid separator 40, and a water quality meter 50.

[0015] The hydrogen SH supplied to the fuel cell system 1 may be by-product hydrogen, which is hydrogen produced as a by-product when producing caustic soda (NaOH) or chlorine gas (Cl2). Alternatively, the hydrogen SH supplied to the fuel cell system 1 may be crude hydrogen produced from a hydrogen production device, such as a water electrolysis device. Furthermore, the hydrogen SH supplied to the fuel cell system 1 may be pure hydrogen supplied from a cartridge, tank, or the like.

[0016] [Fuel cell unit 10] The fuel cell unit 10 generates electricity by chemically reacting hydrogen and oxygen. That is, the fuel cell unit 10 generates electricity by chemically reacting supplied hydrogen SH with oxygen contained in air SA. The fuel cell unit 10 includes a fuel cell stack 11, an output adjustment unit 12, a flow rate adjustment unit 13, and a control unit 14.

[0017] The fuel cell stack 11 generates electricity by chemically reacting the supplied hydrogen SH with oxygen contained in the air SA. The fuel cell stack 11 is, for example, a polymer electrolyte fuel cell (PEFC). The fuel cell stack 11, which is a polymer electrolyte fuel cell, has a stack structure in which a large number of unit cells (fuel cell units) are stacked.

[0018] Each unit cell in the fuel cell stack 11, which is a polymer electrolyte fuel cell, includes a membrane electrode assembly (MEA) having a polymer electrolyte membrane and a pair of electrodes provided on both sides of the polymer electrolyte membrane. One of the pair of electrodes is an air electrode, and the other is a fuel electrode. The polymer electrolyte membrane selectively transports hydrogen ions. Each electrode is made of a porous material. Each of the pair of electrodes has a catalyst layer mainly composed of carbon powder that supports a platinum-based metal catalyst (electrode catalyst), for example, and a gas diffusion layer that is both breathable and electronically conductive. Furthermore, the unit cell has a pair of separators that sandwich the membrane electrode assembly (MEA) from both sides.

[0019] The fuel cell stack 11 discharges exhaust gas EC, which is a mixture of exhaust gas discharged from the fuel cell's fuel electrode, containing hydrogen that has not undergone chemical reaction, and exhaust gas discharged from the fuel cell's air electrode, which is air SA from which oxygen has been consumed.

[0020] The exhaust EC, which is exhaust containing hydrogen that has not undergone chemical reaction and is discharged from the fuel cell's anode, and the exhaust from which oxygen has been consumed from the air SA and is discharged from the fuel cell's cathode, may be mixed outside the fuel cell stack 11.

[0021] The output adjustment unit 12 adjusts the output power output from the fuel cell stack 11 to the outside of the fuel cell unit 10. The output adjustment unit 12 boosts the voltage of the electricity (output power p1) generated by the fuel cell stack 11. The output adjustment unit 12 then outputs a predetermined output (output power P1). The output adjustment unit 12 includes, for example, a DC / DC converter (Direct Current to Direct Current Converter).

[0022] The flow rate adjustment unit 13 adjusts the flow rates of hydrogen SH and air SA supplied from outside the fuel cell unit 10. The flow rate adjustment unit 13 supplies the hydrogen SHs and air SAs after adjusting the flow rates to the fuel cell stack 11. The flow rate adjustment unit 13 includes a control valve and a booster for adjusting the flow rate or pressure of the hydrogen SH, and a control valve and a booster for adjusting the flow rate or pressure of the air SA.

[0023] The control unit 14 controls the fuel cell unit 10 based on a control command from a control unit 20 external to the fuel cell unit 10. The control unit 14 controls the fuel cell stack 11, output adjustment unit 12, and flow rate adjustment unit 13 in the fuel cell unit 10.

[0024] [Control Unit 20] The control unit 20 controls the fuel cell unit 10. The control unit 20 is mainly composed of a computer including, for example, a CPU (Central Processing Unit), a memory device, an auxiliary storage device, and an external input / output interface device. The control unit 20 may be a programmable logic controller (PLC).

[0025] The control unit 20 can control the fuel cell unit 10 through the control unit 14 by sending control commands to the control unit 14 provided in the fuel cell unit 10. The control unit 20 can also obtain data relating to various states of the fuel cell unit 10 from the control unit 14.

[0026] The control unit 20 includes a timer 21 for measuring time. The timer 21 may be a hardware timer or a software timer implemented by a program installed in the control unit 20. The control unit 20 uses the timer 21 to determine whether a predetermined time has elapsed. The control unit 20 may measure time by an interrupt from the timer 21, or may determine whether the time has elapsed by sequentially referring to the count value of the timer 21.

[0027] The function of the timer 21 is not limited to being provided in the control unit 20, but may be provided outside the control unit 20.

[0028] [Energy storage unit 30] The power storage unit 30 supplies startup power when starting up the fuel cell unit 10. The power storage unit 30 may store electricity supplied from an external power source, or may supply the stored electricity to an external device as needed. The power storage unit 30 charges when there is excess power from the fuel cell unit 10 to the external load EX. The power storage unit 30 discharges when there is a shortage of power from the fuel cell unit 10 to the external load EX.

[0029] The power storage unit 30 includes, for example, a lithium ion capacitor, a lithium ion battery, an electric double layer capacitor, or an all-solid-state battery.

[0030] An output Pout is output from the fuel cell system 1 based on the output power P1 supplied from the fuel cell unit 10 and the power Ps input / output from the power storage unit 30. The power storage unit 30 can store (charge) the power of the fuel cell unit 10 after operation, or store power from an external power source (e.g., an AC power system) not shown. The power storage unit 30 may also supply power to an external load EX as needed.

[0031] For example, if the output power P1 of the fuel cell unit 10 is in excess of the demands of the external load EX, the surplus power Ps is stored. If the output power P1 of the fuel cell unit 10 is in excess of the demands of the external load EX, the output Pout output from the fuel cell system 1 is the output power P1 of the fuel cell unit 10 minus the power Ps stored in the power storage unit 30 (Pout=P1-Ps).

[0032] Furthermore, if the output power P1 of the fuel cell unit 10 is insufficient to meet the demands of the external load EX, the shortfall in power Ps is discharged. If the output power P1 of the fuel cell unit 10 is insufficient to meet the demands of the external load EX, the output Pout output from the fuel cell system 1 is the sum of the output power P1 of the fuel cell unit 10 and the power Ps discharged from the power storage unit 30 (Pout=P1+Ps).

[0033] By providing the fuel cell system 1 with the power storage unit 30, the output Pout from the fuel cell system 1 can be stably output.

[0034] [Gas-liquid separator 40] The gas-liquid separator 40 separates the liquid component contained in the exhaust gas EC. The liquid component contained in the exhaust gas EC is water (hereinafter referred to as "produced water") generated by a chemical reaction between hydrogen and oxygen in the fuel cell stack 11. The gas-liquid separator 40 discharges the produced water EL and exhaust gas EG from which the liquid component (produced water EL) has been removed. The exhaust gas EG and the produced water EL are discharged to the outside of the fuel cell system 1.

[0035] [Water quality meter 50] The water quality meter 50 is a device for measuring the quality of the produced water EL.

[0036] For example, the water quality meter 50 measures the sulfate ions (SO4 2- The water quality meter 50 is, for example, an electrical conductivity meter that can measure the electrical conductivity of the produced water EL. This is because a certain correlation can be found between the electrical conductivity of the produced water EL and the concentration of sulfate ions contained in the produced water EL.

[0037] The water quality meter 50 may also be a hydrogen ion concentration meter capable of measuring the hydrogen ion concentration (pH). This is because a certain correlation can be found between the hydrogen ion concentration (pH) of the produced water EL and the concentration of sulfate ions. The water quality meter 50 may also be an ion chromatograph capable of separating, detecting, and quantitatively analyzing the sulfate ions contained in the produced water EL.

[0038] <Processing in the fuel cell system according to the first embodiment> The following describes the processing in the fuel cell system according to the first embodiment. Fig. 2 is a flow chart illustrating the processing in the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment.

[0039] (Step S10) The control unit 20 determines whether the fuel cell unit 10 is in operation. If the fuel cell unit 10 is in operation (YES in step S10), the control unit 20 proceeds to step S20. If the fuel cell unit 10 is not in operation, that is, if the fuel cell unit 10 is stopped (NO in step S10), the control unit 20 ends the process.

[0040] (Step S20) Next, the control unit 20 determines whether the electrical conductivity of the produced water EL is equal to or greater than a first threshold. The control unit 20 controls the water quality meter 50 to measure the electrical conductivity of the produced water EL. The control unit 20 then acquires the electrical conductivity of the produced water EL from the water quality meter 50. The control unit 20 determines whether the electrical conductivity of the produced water EL is equal to or greater than a first threshold, which is a predetermined threshold. The first threshold is, for example, 3 microsiemens per centimeter (μS / cm).

[0041] In step S20, the control unit 20 may provide hysteresis when determining whether the electrical conductivity of the produced water EL is equal to or greater than the first threshold value. The hysteresis may be, for example, 1 microSiemens per centimeter (μS / cm).

[0042] If the electrical conductivity of the produced water EL is equal to or greater than the first threshold value (YES in step S20), the control unit 20 proceeds to step S30. If the electrical conductivity of the produced water EL is less than the first threshold value (NO in step S20), the control unit 20 proceeds to step S70.

[0043] (Step S30) Next, the control unit 20 determines whether the drop in stack voltage is equal to or greater than a second threshold, which is a predetermined threshold. The control unit 20 sends a control command to the control unit 14 included in the fuel cell unit 10 to send data related to the stack voltage. Based on the control command, the control unit 14 sends the stack voltage to the control unit 20. The control unit 20 compares the previously acquired stack voltage with the currently acquired stack voltage, and calculates the dropped voltage of the stack voltage (stack voltage drop).

[0044] If the stack voltage drop is equal to or greater than the second threshold (YES in step S30), the control unit 20 proceeds to step S40. The second threshold is, for example, a voltage value that is 5% of the normal voltage. If the stack voltage drop is less than the second threshold (NO in step S30), the control unit 20 proceeds to step S70.

[0045] (Step S40) The control unit 20 stops operation of the fuel cell unit 10 if the electrical conductivity is equal to or greater than the first threshold in step S20 (YES in step S20) and the stack voltage drop is equal to or greater than the second threshold in step S30 (YES in step S30).

[0046] The control unit 20 starts a timer 21 to measure time.

[0047] (Step S50) Next, the control unit 20 determines whether a predetermined first time has elapsed. The control unit 20 determines whether the first time has elapsed by referring to the timer 21. If the first time has elapsed (YES in step S50), the control unit 20 proceeds to the process in step S60. If the first time has not elapsed (NO in step S50), the control unit 20 returns to step S40 and repeats the process.

[0048] (Step S60) If the first time has elapsed since the fuel cell unit was shut down (YES in step S50), the control unit 20 starts up the fuel cell unit 10.

[0049] (Step S70) The control unit 20 determines whether the control period has elapsed. The control unit 20 determines whether a predetermined control period has elapsed using the timer 21. If the control period has elapsed (YES in step S70), the control unit 20 proceeds to step S10. If the control period has not elapsed (NO in step S50), the control unit 20 repeats the process of step S70.

[0050] The following describes the operation of the fuel cell system according to the first embodiment. Figure 3 is a diagram illustrating the operation of the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment.

[0051] The horizontal axis of Figure 3 represents time, and the vertical axis represents electrical conductivity. Line L1 represents the measurement result of electrical conductivity when an electrical conductivity meter is used as the water quality meter 50. TH1 represents the threshold value. The threshold value TH1 is, for example, 3 microsiemens per centimeter (μS / cm).

[0052] For example, suppose that impurities such as sulfur, bromine, or chlorine are mixed in at time t1. When the impurities are mixed in, the electrical conductivity measured by an electrical conductivity meter, which is an example of a water quality meter 50, increases. When the electrical conductivity becomes equal to or greater than threshold value TH1 at time t2, the control unit 20 stops operation of the fuel cell unit 10.

[0053] The fuel cell unit 10 may be automatically restarted after a certain time has elapsed since shutdown, for example, 30 minutes to 24 hours, preferably 6 hours. After shutdown, the fuel cell unit 10 may be restarted manually, for example, after an operator has confirmed that there are no more impurities in the air.

[0054] The fuel cell system according to the first embodiment can prevent the fuel cell unit from deteriorating due to impurities contained in the hydrogen or air used as fuel. The fuel cell system according to the first embodiment can prevent the fuel cell unit from irreversibly deteriorating due to the inclusion of impurities. Furthermore, the fuel cell system according to the first embodiment can avoid operation in a state where the running costs increase due to the inclusion of impurities.

[0055] If the air supplied to the fuel cell unit temporarily contains impurities such as sulfur-based (sulfur or sulfide), bromine-based (bromine or bromide), chlorine-based (chlorine or chloride), ammonia-based (ammonia and its compounds (ammonium compounds)), volatile organic compounds, metals, etc., they may adhere to the fuel cell catalyst and inhibit the power generation reaction.If the air supplied to the fuel cell unit temporarily contains impurities such as sulfur-based (sulfur or sulfide), bromine-based (bromine or bromide), chlorine-based (chlorine or chloride), ammonia-based (ammonia and its compounds (ammonium compounds)), volatile organic compounds, metals, etc., they may adhere to the fuel cell catalyst and inhibit the power generation reaction, causing a decrease in the fuel cell's electromotive force, which in turn reduces power generation efficiency and increases running costs.

[0056] Some of the sulfur, bromine, and chlorine impurities dissolve in the water produced inside the fuel cell, becoming sulfate ions, bromide ions, and chloride ions, respectively, which are then discharged as wastewater. Because the ion concentrations of sulfate ions, bromide ions, and chloride ions are positively correlated with electrical conductivity, the presence of impurities can be estimated from the measurements taken by the water quality meter. If the electrical conductivity exceeds a threshold value and it is determined that impurities have been present, the fuel cell unit is shut down via the control unit.

[0057] Electrical conductivity meters are easy to maintain and can be used for long-term measurements. In addition, electrical conductivity meters can measure continuously with a sampling period of about 10 seconds.

[0058] In the above example, an electrical conductivity meter was used as the water quality meter 50, but for example, a hydrogen ion concentration meter may also be used as the water quality meter 50, or any other measuring device may be used as long as it can detect substances related to impurities such as sulfur, bromine, and chlorine.

[0059] Second Embodiment A fuel cell system according to a second embodiment will now be described. The fuel cell system according to the second embodiment includes a polymer electrolyte fuel cell unit that generates electricity through a chemical reaction between hydrogen and oxygen, a water quality meter that measures the quality of the water produced when the fuel cell unit generates electricity, and an impurity removal device that removes impurities contained in the oxygen. The fuel cell system according to the second embodiment also includes a control unit that controls the impurity removal device to remove impurities contained in the air based on the water quality measured by the water quality meter.

[0060] FIG. 4 is a diagram showing an outline of the configuration of a fuel cell system 2, which is an example of a fuel cell system according to the second embodiment.

[0061] The fuel cell system 2 is a fuel cell that uses fuel cells. The fuel cell system 2 is a chemical cell that converts chemical energy into electricity by reacting hydrogen with oxygen in the air as fuel. The fuel cell system 2 supplies an output Pout to an external load EX.

[0062] The fuel cell system 2 includes a fuel cell unit 10, a control unit 120, a power storage unit 30, a gas-liquid separator 40, a water quality meter 50, an impurity removal device 150, and a three-way valve 160.

[0063] In the fuel cell system 2, for the configuration common to the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment, the description of the fuel cell system 1 can be referred to and the description will be omitted here.

[0064] [Impurity removal device 150] The impurity removal device 150 is provided as a bypass in the flow path that supplies the air SA. The impurity removal device 150 removes impurities contained in the air SA.

[0065] [Three-way valve 160] The three-way valve 160 switches the flow path of the air SA. The three-way valve 160 switches whether the air supplied from the outside flows directly to the flow rate adjuster 13 or passes through the impurity remover 150 and then flows to the flow rate adjuster 13. The three-way valve 160 is controlled by the control unit 120.

[0066] Although a three-way valve is used in the above example, the same function may be realized by combining two valves instead of the three-way valve.

[0067] [Control Unit 120] The control unit 120 controls the fuel cell unit 10. The control unit 120 also controls the three-way valve 160. Since the control unit 120 has the same hardware configuration as the control unit 20, for details of the control unit 120, please refer to the description of the control unit 20 and detailed description thereof will be omitted.

[0068] <Processing in the fuel cell system according to the second embodiment> The following describes the processing in the fuel cell system according to the second embodiment. Fig. 5 is a flow chart illustrating the processing in a fuel cell system 2, which is an example of a fuel cell system according to the second embodiment.

[0069] (Step S110) The control unit 120 determines whether the fuel cell unit 10 is in operation. If the fuel cell unit 10 is in operation (YES in step S110), the control unit 120 proceeds to step S120. If the fuel cell unit 10 is not in operation, that is, if the fuel cell unit 10 is stopped (NO in step S110), the control unit 120 ends the process.

[0070] (Step S120) Next, the control unit 120 determines whether the electrical conductivity of the produced water EL is equal to or greater than a first threshold. The control unit 120 controls the water quality meter 50 to measure the electrical conductivity of the produced water EL. The control unit 120 then acquires the electrical conductivity of the produced water EL from the water quality meter 50. The control unit 120 determines whether the electrical conductivity of the produced water EL is equal to or greater than a first threshold, which is a predetermined threshold. The first threshold is, for example, 3 microsiemens per centimeter (μS / cm).

[0071] If the electrical conductivity of the produced water EL is equal to or greater than the first threshold value (YES in step S120), the control unit 120 proceeds to step S130. If the electrical conductivity of the produced water EL is less than the first threshold value (NO in step S120), the control unit 120 proceeds to step S140.

[0072] In step S120, the control unit 120 may provide hysteresis when determining whether the electrical conductivity of the produced water EL is equal to or greater than the first threshold. The hysteresis is, for example, 1 microsiemens per centimeter (μS / cm). By providing hysteresis, chattering of the three-way valve 160 near the first threshold can be prevented.

[0073] (Step S130) Next, the control unit 120 determines whether the drop in stack voltage is equal to or greater than a second threshold, which is a predetermined threshold. The control unit 120 sends a control command to the control unit 14 included in the fuel cell unit 10 to send data related to the stack voltage. Based on the control command, the control unit 14 sends the stack voltage to the control unit 120. The control unit 120 compares the previously acquired stack voltage with the currently acquired stack voltage, and calculates the dropped stack voltage (stack voltage drop).

[0074] If the stack voltage drop is equal to or greater than the second threshold (YES in step S130), the control unit 120 proceeds to step S150. If the stack voltage drop is less than the second threshold (NO in step S130), the control unit 120 proceeds to step S160.

[0075] (Step S140) The control unit 120 switches the three-way valve 160 from B to A. That is, the control unit 120 switches the three-way valve 160 and controls it so that the air SA flows directly to the flow rate adjuster 13. After switching the three-way valve 160 from B to A, the control unit 120 proceeds to the process at step S160.

[0076] (Step S150) The control unit 120 switches the three-way valve 160 from A to B. That is, the control unit 120 switches the three-way valve 160 to control the air SA to flow through the impurity removal device 150 to the flow rate adjustment unit 13. After switching the three-way valve 160 from A to B, the control unit 120 proceeds to step S160.

[0077] (Step S160) The control unit 120 determines whether the control period has elapsed. The control unit 120 determines whether a predetermined control period has elapsed using the timer 21. If the control period has elapsed (YES in step S160), the control unit 120 proceeds to step S110. If the control period has not elapsed (NO in step S160), the control unit 120 repeats the process of step S160.

[0078] As described above, the control unit 120 controls the flow path of the air SA to be switched depending on the measurement result obtained by the water quality meter 50.

[0079] The following describes the operation of the fuel cell system according to the second embodiment. Fig. 6 is a diagram illustrating the operation of the fuel cell system 2, which is an example of the fuel cell system according to the second embodiment.

[0080] The horizontal axis of Figure 6 represents time, and the vertical axis represents electrical conductivity. Line L2 represents the measurement result of electrical conductivity when an electrical conductivity meter is used as the water quality meter 50. TH1 represents the threshold value. The threshold value TH1 is, for example, 3 microsiemens per centimeter (μS / cm). The hysteresis h is 1 microsiemens per centimeter (μS / cm).

[0081] For example, suppose that impurities such as sulfur, bromine, or chlorine are mixed in at time t11. When the impurities are mixed in, the electrical conductivity measured by an electrical conductivity meter, which is an example of a water quality meter 50, increases. When the electrical conductivity exceeds threshold value TH1 at time t12, the control unit 120 switches the flow path of the three-way valve 160 from A to B. When the flow path of the three-way valve 160 is switched from A to B, the impurities are removed by the impurity removal device 150, and the electrical conductivity gradually decreases. Then, when the electrical conductivity decreases below threshold value TH1 (TH1-h, taking hysteresis into account) at time t13, the control unit 120 switches the flow path of the three-way valve 160 from B to A.

[0082] According to the fuel cell system of the second embodiment, impurities contained in the air supplied to the fuel cell unit are removed by an impurity removal device, thereby preventing the fuel cell unit from being deteriorated by impurities contained in the air. According to the fuel cell system of the second embodiment, irreversible deterioration of the fuel cell unit due to the inclusion of impurities can be prevented. Furthermore, according to the fuel cell system of the second embodiment, operation in a state in which the running costs increase due to the inclusion of impurities can be avoided.

[0083] Furthermore, the fuel cell system according to the second embodiment can continue to operate without irreversible deterioration of the fuel cell unit by removing impurities even when impurities are temporarily present in the air. Also, the fuel cell system according to the second embodiment does not pass the air through the impurity removal device all the time, but passes the air through it only when impurities are present, thereby reducing pressure loss in the impurity removal device when there are no impurities, and reducing the power required for the air compressor.

[0084] In the fuel cell system according to the second embodiment, the fuel cell unit may be stopped under desired conditions, as in the fuel cell system according to the first embodiment. In other words, the control unit in the fuel cell system according to the second embodiment may control the stopping of the fuel cell unit or the switching of the air flow path based on the measurement results obtained by the water quality meter. For example, in the fuel cell system according to the second embodiment, the fuel cell unit may be controlled to be stopped after the switching of the air flow path has been performed a desired number of times at first.

[0085] Third Embodiment A fuel cell system according to a third embodiment will now be described. The fuel cell system according to the third embodiment includes a polymer electrolyte fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, a water quality meter that measures the quality of the water produced when the fuel cell unit generates electricity, and an impurity removal device that removes impurities contained in the hydrogen. The fuel cell system according to the third embodiment also includes a control unit that controls the impurity removal device to remove impurities contained in the hydrogen based on the water quality measured by the water quality meter.

[0086] FIG. 7 is a diagram showing an outline of the configuration of a fuel cell system 3, which is an example of a fuel cell system according to the third embodiment.

[0087] The fuel cell system 3 is a fuel cell that uses fuel cells. The fuel cell system 3 is a chemical cell that converts chemical energy into electricity by reacting hydrogen with oxygen in the air as fuel. The fuel cell system 3 supplies an output Pout to an external load EX.

[0088] The fuel cell system 3 includes a fuel cell unit 10 , a control unit 220 , a power storage unit 30 , a gas-liquid separator 40 , a water quality meter 50 , an impurity removal device 250 , and a three-way valve 260 .

[0089] In the fuel cell system 3, for the configuration common to the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment, the description of the fuel cell system 1 can be referred to and the description will be omitted here.

[0090] [Impurity removal device 250] The impurity removal device 250 is provided as a bypass in the flow path for supplying hydrogen SH. The impurity removal device 250 removes impurities contained in the hydrogen SH.

[0091] [Three-way valve 260] The three-way valve 260 switches the flow path of the hydrogen SH. The three-way valve 260 switches whether hydrogen supplied from the outside flows directly to the flow rate regulator 13 or passes through the impurity removal device 250 and then flows to the flow rate regulator 13. The three-way valve 260 is controlled by the control unit 220.

[0092] [Control unit 220] The control unit 220 controls the fuel cell unit 10. The control unit 220 also controls the three-way valve 260. Since the control unit 220 has the same hardware configuration as the control unit 20, for details of the control unit 220, please refer to the description of the control unit 20 and detailed description thereof will be omitted.

[0093] <Processing in the fuel cell system according to the third embodiment> The processing in the fuel cell system according to the third embodiment is similar to that in the fuel cell system according to the second embodiment, and therefore the description of the fuel cell system according to the second embodiment should be referred to, and detailed description thereof will be omitted. Similar to the control unit 120, the control unit 220 controls the switching of the flow path of the hydrogen SH based on the measurement results obtained by the water quality meter 50.

[0094] The fuel cell system according to the third embodiment has the same effects and functions as the fuel cell system according to the second embodiment.

[0095] In the fuel cell system according to the third embodiment, like the fuel cell system according to the second embodiment, an impurity removal device may also be provided on the air supply side.

[0096] Furthermore, in the fuel cell system according to the third embodiment, the fuel cell unit may be stopped under desired conditions, as in the fuel cell system according to the first embodiment. In other words, the control unit in the fuel cell system according to the third embodiment may control the stopping of the fuel cell unit or the switching of the hydrogen flow path based on the measurement results obtained by the water quality meter. For example, in the fuel cell system according to the third embodiment, the fuel cell unit may be controlled to be stopped after the hydrogen flow path has been switched a desired number of times at first.

[0097] Fourth Embodiment A fuel cell system according to a fourth embodiment will now be described. The fuel cell system according to the fourth embodiment includes a polymer electrolyte fuel cell unit that generates electricity through a chemical reaction between hydrogen and oxygen, and a water quality meter that measures the quality of water produced when the fuel cell unit generates electricity. The fuel cell system according to the fourth embodiment also includes a control unit that controls the refresh process in the fuel cell unit based on the water quality measured by the water quality meter.

[0098] FIG. 8 is a diagram showing an outline of the configuration of a fuel cell system 4, which is an example of a fuel cell system according to the fourth embodiment.

[0099] The fuel cell system 4 is a fuel cell that uses fuel cells. The fuel cell system 4 is a chemical cell that converts chemical energy into electricity by reacting hydrogen with oxygen in the air as fuel. The fuel cell system 4 supplies an output Pout to an external load EX.

[0100] The fuel cell system 4 includes a fuel cell unit 10, a control unit 320, a power storage unit 30, a gas-liquid separator 40, and a water quality meter 50.

[0101] In the fuel cell system 4, for the configuration common to the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment, the description of the fuel cell system 1 can be referred to and the description thereof will be omitted here.

[0102] [Control Unit 320] The control unit 320 controls the fuel cell unit 10. Since the control unit 320 has the same hardware configuration as the control unit 20, for details of the control unit 320, please refer to the description of the control unit 20 and detailed description thereof will be omitted.

[0103] <Processing in the fuel cell system according to the fourth embodiment> The following describes the processing in the fuel cell system according to the fourth embodiment. Fig. 9 is a flow chart illustrating the processing in a fuel cell system 4, which is an example of a fuel cell system according to the fourth embodiment.

[0104] (Step S210) The control unit 320 determines whether the fuel cell unit 10 is in operation. If the fuel cell unit 10 is in operation (YES in step S210), the control unit 320 proceeds to step S220. If the fuel cell unit 10 is not in operation, that is, if the fuel cell unit 10 is stopped (NO in step S210), the control unit 320 ends the process.

[0105] (Step S220) Next, the control unit 320 determines whether the electrical conductivity of the produced water EL is equal to or greater than a first threshold. The control unit 320 controls the water quality meter 50 to measure the electrical conductivity of the produced water EL. The control unit 320 then acquires the electrical conductivity of the produced water EL from the water quality meter 50. The control unit 320 determines whether the electrical conductivity of the produced water EL is equal to or greater than a first threshold, which is a predetermined threshold. The first threshold is, for example, 3 microsiemens per centimeter (μS / cm).

[0106] If the electrical conductivity of the produced water EL is equal to or greater than the first threshold value (YES in step S220), the control unit 320 proceeds to step S230. If the electrical conductivity of the produced water EL is less than the first threshold value (NO in step S220), the control unit 320 proceeds to step S240.

[0107] In step S220, the control unit 320 may provide hysteresis when determining whether the electrical conductivity of the produced water EL is equal to or greater than the first threshold value, for example, 1 microSiemens per centimeter (μS / cm).

[0108] (Step S230) Next, the control unit 320 determines whether the drop in stack voltage is equal to or greater than a second threshold, which is a predetermined threshold. The control unit 320 sends a control command to the control unit 14 included in the fuel cell unit 10 to send data related to the stack voltage. Based on the control command, the control unit 14 sends the stack voltage to the control unit 320. The control unit 320 compares the previously acquired stack voltage with the currently acquired stack voltage, and calculates the dropped stack voltage (stack voltage drop).

[0109] If the stack voltage drop is equal to or greater than the second threshold (YES in step S230), the control unit 320 proceeds to step S250. If the stack voltage drop is less than the second threshold (NO in step S230), the control unit 320 proceeds to step S260.

[0110] (Step S240) The control unit 320 stops the enhanced refresh operation. Specifically, the control unit 320 controls the refresh operation so that the refresh process is performed, for example, at a normal refresh cycle (for example, a 12-hour cycle). After stopping the enhanced refresh operation, the control unit 320 proceeds to step S260.

[0111] (Step S250) The control unit 320 starts the enhanced refresh operation. Specifically, the control unit 320 controls the refresh operation so that the refresh process is performed at a refresh period (e.g., a 6-hour period) that is shorter than the normal refresh period (e.g., a 12-hour period). After starting the enhanced refresh operation, the control unit 320 proceeds to step S260.

[0112] (Step S260) The control unit 320 determines whether the control period has elapsed. The control unit 320 determines whether a predetermined control period has elapsed, using the timer 21. If the control period has elapsed (YES in step S260), the control unit 320 proceeds to step S210. If the control period has not elapsed (NO in step S260), the control unit 320 repeats the process of step S260.

[0113] The operation of the fuel cell system according to the fourth embodiment will be described below. Fig. 10 is a diagram illustrating the operation of the fuel cell system 4, which is an example of the fuel cell system according to the fourth embodiment.

[0114] In the upper graph of FIG. 10, the horizontal axis represents time, and the vertical axis represents electrical conductivity. Line L3 represents the measurement result of electrical conductivity when an electrical conductivity meter is used as the water quality meter 50. TH1 represents the threshold value. The threshold value TH1 is, for example, 3 microsiemens per centimeter (μS / cm). The hysteresis h is 1 microsiemens per centimeter (μS / cm).

[0115] In the graph at the bottom of Figure 10, the horizontal axis represents time, and the vertical axis represents the timing of the refresh operation. Normal refresh operations are indicated by hollow arrows, and enhanced refresh operations are indicated by solid arrows. Normal refresh operations are repeated at a refresh cycle PRD1 (e.g., 12 hours). Enhanced refresh operations are repeated at a refresh cycle PRD2 (e.g., 6 hours).

[0116] The refresh operation is performed, for example, by stopping the fuel cell unit 10 once and then restarting it.

[0117] As shown in Figure 10, when the refresh operation is performed, the electrical conductivity temporarily increases. The reason why the electrical conductivity temporarily increases when the refresh operation is performed is because impurities attached to the electrodes, etc. are dissociated and mixed into the produced water EL. Therefore, the measurement results of the water quality meter 50 while the refresh operation is being performed will be ignored.

[0118] 10, it is assumed that impurities are mixed in during a period TRM1. When the electrical conductivity exceeds a threshold TH1, the control unit 320 intensifies the refresh operation for a period TRM2 until the electrical conductivity falls below the threshold TH1 (TH1-h taking into account the hysteresis h). When the refresh operation is intensified, the control unit 320 sets the refresh period to a refresh period PRD2 that is shorter than the normal refresh period (refresh period PRD1), for example. For example, the control unit 320 performs the refresh operation at a period that is half the period of the normal refresh operation.

[0119] The control unit 320 switches to normal refresh operation after the electrical conductivity becomes lower than the threshold value TH1 (TH1-h taking into account the hysteresis h).

[0120] In the fuel cell system according to the fourth embodiment, the catalyst can be thoroughly cleaned and adhering impurities can be expelled by increasing the frequency of the shutdown, restart, and refresh cycles, thereby recovering from the decrease in electromotive force and power generation efficiency of the fuel cell unit.

[0121] In the fuel cell systems according to the first to third embodiments, refresh operation may be controlled as in the fuel cell system according to the fourth embodiment. Also, the fuel cell system according to the fourth embodiment may be provided with an impurity removal device as in the fuel cell system according to the second or third embodiment.

[0122] Fifth Embodiment A fuel cell system according to the fifth embodiment will now be described. The fuel cell system according to the fifth embodiment includes a plurality of fuel cell units.

[0123] FIG. 11 is a diagram showing an outline of the configuration of a fuel cell system 5, which is an example of a fuel cell system according to a fifth embodiment.

[0124] The fuel cell system 5 is a fuel cell that uses fuel cells. The fuel cell system 5 is a chemical cell that uses hydrogen as fuel and converts chemical energy into electricity by reacting with oxygen in the air.

[0125] The fuel cell system 5 includes a fuel cell unit 410A, a fuel cell unit 410B, a fuel cell unit 410C, and a fuel cell unit 410D, and a control unit 420. Note that power-related components (e.g., a power storage unit) are omitted from Fig. 11. The fuel cell system 5 also includes a gas-liquid separator 440A, a gas-liquid separator 440B, a gas-liquid separator 440C, and a gas-liquid separator 440D corresponding to the fuel cell unit 410A, the fuel cell unit 410B, the fuel cell unit 410C, and the fuel cell unit 410D, respectively. The fuel cell system 5 also includes a water quality meter 50, an impurity removal device 450, an impurity removal device 451, and a three-way valve 460 and a three-way valve 461.

[0126] In the fuel cell system 5, for the configuration common to the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment, the description of the fuel cell system 1 can be referred to and the description will be omitted here.

[0127] [Fuel cell unit 410A, fuel cell unit 410B, fuel cell unit 410C, and fuel cell unit 410D] The fuel cell system 5 includes a plurality of fuel cell units. In the example of the fuel cell system 5, four fuel cell units are included, but the number of fuel cell units is not limited to four and may be two or more. For details of the fuel cell units, please refer to the description of the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment, and detailed description will be omitted.

[0128] [Gas-liquid separator 440A, gas-liquid separator 440B, gas-liquid separator 440C, and gas-liquid separator 440D] The fuel cell system 5 includes a plurality of gas-liquid separators corresponding to the plurality of fuel cell units. Specifically, the fuel cell system 5 includes a gas-liquid separator 440A corresponding to the fuel cell unit 410A. The gas-liquid separator 440A separates the liquid component contained in the exhaust ECA discharged from the fuel cell unit 410A.

[0129] Similarly, the fuel cell system 5 includes a gas-liquid separator 440B, a gas-liquid separator 440C, and a gas-liquid separator 440D corresponding to the fuel cell unit 410B, the fuel cell unit 410C, and the fuel cell unit 410D, respectively. The gas-liquid separator 440B, the gas-liquid separator 440C, and the gas-liquid separator 440D treat the exhaust ECB, the exhaust ECC, and the exhaust ECD, respectively.

[0130] Gas-liquid separator 440A, gas-liquid separator 440B, gas-liquid separator 440C and gas-liquid separator 440D have the same functions as gas-liquid separator 40 in fuel cell system 1, so for details please refer to the description of gas-liquid separator 40 in fuel cell system 1.

[0131] The exhaust gas and produced water discharged from the gas-liquid separator 440A, the gas-liquid separator 440B, the gas-liquid separator 440C, and the gas-liquid separator 440D are collected into a single pipe and discharged as the exhaust gas EG and the produced water EL, respectively, to the outside of the fuel cell system 5. The produced water EL is a collection of the produced water discharged from the multiple gas-liquid separators.

[0132] The water quality meter 50 measures the quality of the produced water EL, which is the combined produced water discharged from the gas-liquid separator 440A, the gas-liquid separator 440B, the gas-liquid separator 440C, and the gas-liquid separator 440D.

[0133] [Impurity removal device 450 and impurity removal device 451] The impurity removal device 450 is provided as a bypass in the flow path that supplies the air SA. The impurity removal device 450 removes impurities contained in the air SA. The impurity removal device 451 is provided as a bypass in the flow path that supplies the hydrogen SH. The impurity removal device 451 removes impurities contained in the hydrogen SH.

[0134] [Three-way valve 460 and three-way valve 461] The three-way valve 460 switches the flow path of the air SA. The three-way valve 460 switches whether the air SA supplied from the outside flows directly to each of the plurality of fuel cell units, or passes through the impurity removal device 450 and then flows to each of the plurality of fuel cell units. The three-way valve 460 is controlled by the control unit 420.

[0135] The three-way valve 461 switches the flow path of the hydrogen SH. The three-way valve 461 switches whether the hydrogen SH supplied from the outside flows directly to each of the multiple fuel cell units, or passes through the impurity removal device 451 and then flows to each of the multiple fuel cell units. The three-way valve 461 is controlled by the control unit 420.

[0136] [Control Unit 420] Control unit 420 controls each of fuel cell unit 410A, fuel cell unit 410B, fuel cell unit 410C, and fuel cell unit 410D. Control unit 420 also controls three-way valve 460 and three-way valve 461. Since control unit 420 has the same hardware configuration as control unit 20, for details of control unit 420, please refer to the description of control unit 20 and detailed description thereof will be omitted.

[0137] As shown in the fuel cell systems according to the first to fourth embodiments, the control unit 420 controls the three-way valve and the fuel cell unit (stop and refresh operation).

[0138] According to the fuel cell system of the fifth embodiment, in a fuel cell system having multiple fuel cell units, it is possible to prevent deterioration of each of the multiple fuel cell units due to impurities contained in the hydrogen or air that serves as fuel.

[0139] Sixth Embodiment A fuel cell system according to a sixth embodiment will be described. The fuel cell system according to the sixth embodiment includes a plurality of fuel cell units. The fuel cell system according to the sixth embodiment differs from the fuel cell system according to the fifth embodiment in the configuration of the gas-liquid separator.

[0140] 12 is a diagram showing an outline of the configuration of a fuel cell system 6, which is an example of a fuel cell system according to a sixth embodiment. The fuel cell system 6 includes a gas-liquid separator 540 instead of the gas-liquid separator 440A, the gas-liquid separator 440B, the gas-liquid separator 440C, and the gas-liquid separator 440D in the fuel cell system 5, which is an example of a fuel cell system according to a fifth embodiment.

[0141] In the fuel cell system 6, for the configuration common to the fuel cell system 5, which is an example of a fuel cell system according to the fifth embodiment, the description of the fuel cell system 5 can be referred to, and the description will be omitted here.

[0142] [Gas-liquid separator 540] The fuel cell system 6 includes a gas-liquid separator 540 connected to each of the multiple fuel cell units. The gas-liquid separator 540 separates the liquid components contained in the exhaust ECA, exhaust ECB, exhaust ECC, and exhaust ECD discharged from the multiple fuel cell units. The gas-liquid separator 540 separates the exhaust EG and the produced water EL, which are then discharged to the outside. The produced water EL is a collection of the produced water discharged from the multiple fuel cell units.

[0143] According to the fuel cell system of the sixth embodiment, in a fuel cell system having multiple fuel cell units, it is possible to prevent deterioration of each of the multiple fuel cell units due to impurities contained in the hydrogen or air that serves as fuel.

[0144] Seventh Embodiment A fuel cell system according to a seventh embodiment will be described. The fuel cell system according to the seventh embodiment includes a polymer electrolyte fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen. The fuel cell system according to the seventh embodiment also includes a first water quality meter that measures the quality of water produced on the air side during power generation in the fuel cell unit, and a first impurity removal device that removes impurities contained in the air. The fuel cell system according to the seventh embodiment also includes a second water quality meter that measures the quality of water produced on the fuel electrode side during power generation in the fuel cell unit, and a second impurity removal device that removes impurities contained in the hydrogen. The fuel cell system according to the seventh embodiment also includes a control unit that controls the first impurity removal device to remove impurities contained in the air based on the water quality measured by the first water quality meter. The control unit in the fuel cell system according to the seventh embodiment also controls the second impurity removal device to remove impurities contained in the hydrogen based on the water quality measured by the second water quality meter.

[0145] FIG. 13 is a diagram showing an outline of the configuration of a fuel cell system 7, which is an example of a fuel cell system according to the seventh embodiment.

[0146] The fuel cell system 7 is a fuel cell that uses fuel cells. The fuel cell system 7 is a chemical cell that converts chemical energy into electricity by reacting hydrogen with oxygen in the air as fuel. The fuel cell system 7 supplies an output Pout to an external load EX.

[0147] The fuel cell system 7 includes a fuel cell unit 710, a control unit 720, a power storage unit 30, a gas-liquid separator 740a and a gas-liquid separator 740h, a water quality meter 50a and a water quality meter 50h, an impurity removal device 750a and an impurity removal device 750h, and a three-way valve 760a and a three-way valve 760h.

[0148] In the fuel cell system 7, for the configurations common to the fuel cell system 1, which is an example of the fuel cell system according to the first embodiment, the description of the fuel cell system 1 can be referred to, and detailed description thereof will be omitted here.

[0149] [Fuel Cell Unit 710] The fuel cell unit 710 includes a fuel cell stack 711 instead of the fuel cell stack 11 in the fuel cell unit 10. The fuel cell stack 711 discharges exhaust ECa from the air electrode side. The fuel cell stack 711 also discharges exhaust ECh from the fuel electrode side. The fuel cell stack 11 discharges exhaust EC, which is a mixture of exhaust discharged from the air electrode side and exhaust discharged from the fuel electrode side. The fuel cell stack 711 differs from the fuel cell stack 11 in that the fuel cell stack 711 discharges the exhaust discharged from the air electrode side and the exhaust discharged from the fuel electrode side without mixing them. The fuel cell stack 711 has the same functions and configuration as the fuel cell stack 11, except that the fuel cell stack 711 discharges the exhaust discharged from the air electrode side and the exhaust discharged from the fuel electrode side without mixing them.

[0150] [Gas-liquid separator 740a and gas-liquid separator 740h] The gas-liquid separator 740a separates the liquid components contained in the exhaust ECa. The gas-liquid separator 740a discharges the produced water ELa and exhaust EGa, which is the exhaust ECa from which the liquid components (produced water ELa) have been removed, and the exhaust EGa and produced water ELa are discharged to the outside of the fuel cell system 7. The gas-liquid separator 740h separates the liquid components contained in the exhaust ECh. The gas-liquid separator 740h discharges the produced water ELh and exhaust ETh, which is the exhaust ECh from which the liquid components (produced water ELh) have been removed, and the exhaust ETh and produced water ELh are discharged to the outside of the fuel cell system 7.

[0151] [Water quality meter 50a and water quality meter 50h] The water quality meter 50a is a device for measuring the quality of the produced water ELa. The water quality meter 50h is a device for measuring the quality of the produced water ELh.

[0152] [Impurity removal device 750a and impurity removal device 750h] The impurity removal device 750a is provided as a bypass in the flow path that supplies the air SA. The impurity removal device 750a removes impurities contained in the air SA. Furthermore, the impurity removal device 750h is provided as a bypass in the flow path that supplies the hydrogen SH. The impurity removal device 750h removes impurities contained in the hydrogen SH.

[0153] [Three-way valve 760a and three-way valve 760h] The three-way valve 760a switches the flow path of the air SA. The three-way valve 760a switches whether the air supplied from the outside flows directly to the flow rate adjuster 13 or passes through the impurity removal device 750a before flowing to the flow rate adjuster 13. The three-way valve 760a is controlled by the control unit 720. The three-way valve 760h switches the flow path of the hydrogen SH. The three-way valve 760h switches whether the hydrogen supplied from the outside flows directly to the flow rate adjuster 13 or passes through the impurity removal device 750h before flowing to the flow rate adjuster 13. The three-way valve 760h is controlled by the control unit 720.

[0154] Although a three-way valve is used in the above example, the same function may be realized by combining two valves instead of the three-way valve.

[0155] [Control Unit 720] The control unit 720 controls the fuel cell unit 710. The control unit 720 also controls each of the three-way valve 760a and the three-way valve 760h. For example, if the control unit 720 determines that the quality of the produced water ELa measured by the water quality meter 50a is poor, the control unit 720 controls the three-way valve 760a to switch so that the water flows to the impurity removal device 750a. For example, if the control unit 720 determines that the quality of the produced water ELh measured by the water quality meter 50h is poor, the control unit 720 controls the three-way valve 760h to switch so that the water flows to the impurity removal device 750h.

[0156] For specific control, please refer to the description of the fuel cell system according to the second or third embodiment, and detailed description will be omitted here.

[0157] According to the fuel cell system of the seventh embodiment, impurities contained in the air or hydrogen supplied to the fuel cell unit can be removed by the impurity removal device. Furthermore, according to the fuel cell system of the seventh embodiment, by removing the impurities contained in the air or hydrogen, deterioration of the fuel cell unit due to the impurities contained in the air or hydrogen can be suppressed.

[0158] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0159] 1, 2, 3, 4, 5, 6, 7 Fuel Cell System 10, 410A, 410B, 410C, 410D, 710 Fuel Cell Unit 20, 120, 220, 320, 420, 720 control unit 30 Energy Storage Unit 40, 440A, 440B, 440C, 440D, 540, 740a, 740h gas-liquid separator 50, 50a, 50h water quality meter 150, 250, 450, 451, 750a, 750h Impurity removal equipment 160, 260, 460, 461, 760a, 760h three-way valve EC, ECA, ECB, ECC, ECD, ECa, ECh exhaust EG, EGa, ETh exhaust EL, ELa, ELh produced water SA, SAs Air SH, SHs hydrogen TH1 threshold

Claims

1. A polymer electrolyte fuel cell unit that generates electricity through a chemical reaction between hydrogen and oxygen; a water quality meter for measuring the quality of water produced when the fuel cell unit generates electricity; an impurity removal device that removes impurities contained in at least one of the hydrogen and the oxygen-containing air; a control unit that controls the impurity removal device to remove impurities contained in at least one of the hydrogen and the air based on the water quality measured by the water quality meter; and Equipped with the control unit controls the fuel cell unit to strengthen a refresh operation in the fuel cell unit when the electrical conductivity measured by the water quality meter is equal to or greater than a first threshold value; Fuel cell system.

2. a valve provided in a flow path to which the hydrogen or the oxygen is supplied, for switching the hydrogen or the oxygen supplied to the flow path so that the hydrogen or the oxygen flows directly to the fuel cell unit or passes through the impurity removal device and then flows directly to the fuel cell unit; The control unit controls the valve to switch based on the water quality measured by the water quality meter. The fuel cell system according to claim 1 .

3. The impurity is any one of sulfur, sulfide, bromine, bromide, chlorine, chloride, ammonia, ammonium compounds, volatile organic compounds, or metals; The fuel cell system according to claim 1 .

4. the control unit controls the fuel cell unit to stop when the electrical conductivity measured by the water quality meter is equal to or greater than a first threshold value; The fuel cell system according to any one of claims 1 to 3.

5. A plurality of the fuel cell units are provided. The fuel cell system according to any one of claims 1 to 3.

6. the water quality meter measures the quality of the generated water obtained by collecting the generated water from each of the plurality of fuel cell units; The fuel cell system according to claim 5 .

7. a gas-liquid separator connected to each of the plurality of fuel cell units; The fuel cell system according to claim 5 .

8. The hydrogen is by-product hydrogen. The fuel cell system according to any one of claims 1 to 3.

9. The hydrogen is crude hydrogen produced from a hydrogen production device. The fuel cell system according to any one of claims 1 to 3.

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