Fuel cell system

Abstract

This disclosure provides a fuel cell system that suppresses performance degradation even when impurities such as sulfur-based (sulfur or sulfides), bromine-based (bromine or bromides), 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 solid polymer fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen; a water quality meter that measures the water 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 a fuel cell system.

Background Art

[0002] Patent Document 1 discloses an operating method of a solid polymer fuel cell including an avoidance step of avoiding the solid polymer fuel cell from a battery performance degradation region when it is determined that the solid polymer fuel cell is in the battery performance degradation region. Patent Document 2 discloses an ion quantitative analysis method using the fluorine ion concentration detected by ion chromatography from the anode side and cathode side drain waters of a polymer electrolyte membrane fuel cell as an index of the decomposition components of the polymer electrolyte membrane.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] 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 may be temporarily mixed into hydrogen or air supplied to a fuel cell. When 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 mixed into hydrogen or air, the impurities may adhere to the catalyst of the fuel cell and inhibit the power generation reaction.

[0005] This disclosure provides a fuel cell system that suppresses performance degradation even when impurities such as sulfur-based (sulfur or sulfides), bromine-based (bromine or bromides), 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] This disclosure provides a fuel cell system comprising: a solid polymer fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen; a water quality meter that measures the water 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. [Effects of the Invention]

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

[0008] [Figure 1] Figure 1 is a diagram showing a schematic configuration of the fuel cell system according to the first embodiment. [Figure 2] Figure 2 is a flowchart illustrating the processing in the fuel cell system according to the first embodiment. [Figure 3] Figure 3 is a diagram illustrating the operation of the fuel cell system according to the first embodiment. [Figure 4] Figure 4 is a diagram showing a schematic configuration of the fuel cell system according to the second embodiment. [Figure 5] Figure 5 is a flowchart illustrating the processing in the fuel cell system according to the second embodiment. [Figure 6]Figure 6 is a diagram illustrating the operation of the fuel cell system according to the second embodiment. [Figure 7] Figure 7 is a diagram showing a schematic configuration of the fuel cell system according to the third embodiment. [Figure 8] Figure 8 is a diagram showing a schematic configuration of the fuel cell system according to the fourth embodiment. [Figure 9] Figure 9 is a flowchart illustrating the processing in the fuel cell system according to the fourth embodiment. [Figure 10] Figure 10 is a diagram illustrating the operation of the fuel cell system according to the fourth embodiment. [Figure 11] Figure 11 is a diagram showing a schematic configuration of the fuel cell system according to the fifth embodiment. [Figure 12] Figure 12 is a diagram showing a schematic configuration of the fuel cell system according to the sixth embodiment. [Figure 13] Figure 13 is a diagram showing a schematic configuration of the fuel cell system according to the seventh embodiment. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the attached drawings. However, this disclosure is not limited to these examples, and all modifications are intended to be included in the meaning and scope equivalent to the claims, as indicated by the claims.

[0010] In addition, regarding the descriptions and drawings of each embodiment, components having substantially the same or corresponding functional configurations may be denoted by the same reference numerals, thereby omitting redundant explanations. Furthermore, for ease of understanding, the scale of each part in the drawings may differ from that of the actual parts.

[0011] ≪First Embodiment≫ The fuel cell system according to the first embodiment will be described. The fuel cell system according to the first embodiment includes a solid polymer fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, and a water quality meter that measures the water quality of the generated water produced during the power generation of the fuel cell unit. Further, the fuel cell system according to the first embodiment 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 the fuel cell system according to the first embodiment.

[0013] The fuel cell system 1 is a fuel cell that uses fuel cell cells. The fuel cell system 1 is a chemical battery that converts chemical energy into electricity by reacting hydrogen as fuel with oxygen in the air. 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, for example, by-product hydrogen that is by-produced when producing caustic soda (NaOH) and chlorine gas (Cl2). Further, 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 by a cartridge, a 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 the supplied hydrogen SH with oxygen contained in the 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 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, being a polymer electrolyte fuel cell, has a stack structure in which a large number of unit cells (fuel cell cells) are stacked.

[0018] A unit cell in a fuel cell stack 11, which is a polymer electrolyte fuel cell, comprises a membrane electrode assembly (MEA) consisting of 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 of the electrodes is formed from a porous material. Each of the pair of electrodes has, for example, a catalyst layer mainly composed of carbon powder supporting a platinum-based metal catalyst (electrode catalyst), and a gas diffusion layer that has both permeability and electronic conductivity. Furthermore, the single cell has a pair of separators that sandwich the membrane electrode assembly (MEA) from both sides.

[0019] The fuel cell stack 11 emits exhaust EC. Exhaust EC is a mixture of exhaust gas containing hydrogen that remains unreacted after the fuel electrode of the fuel cell and exhaust gas from which oxygen has been consumed from the air SA emitted from the air electrode of the fuel cell.

[0020] The exhaust EC may be a mixture outside the fuel cell stack 11 of exhaust gas containing hydrogen that remains unreacted and is discharged from the fuel electrode of the fuel cell, and exhaust gas from which oxygen has been consumed from the air SA discharged from the air electrode of the fuel cell.

[0021] The output adjustment unit 12 adjusts the output that is output from the fuel cell stack 11 to the outside of the fuel cell unit 10. The output adjustment unit 12 boosts the electricity (output power p1) generated by the fuel cell stack 11. Then, the output adjustment unit 12 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 adjusted hydrogen SHs and air SAs to the fuel cell stack 11. The flow rate adjustment unit 13 includes control valves and boosters for adjusting the flow rate or pressure of hydrogen SH and control valves and boosters for adjusting the flow rate or pressure of air SA.

[0023] The control unit 14 controls the fuel cell unit 10 based on control commands from an external control unit 20. The control unit 14 controls the fuel cell stack 11, the output adjustment unit 12, and the 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 primarily composed of a computer including, for example, a CPU (Central Processing Unit), memory device, auxiliary storage device, and external input / output interface device. The control unit 20 may also be a programmable logic controller (PLC).

[0025] The control unit 20 can control the fuel cell unit 10 by transmitting control commands to the control unit 14 of the fuel cell unit 10, thereby controlling the fuel cell unit 10 through the control unit 14. The control unit 20 can also acquire data regarding 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, for example, measure the time by receiving an interrupt from the timer 21, or it may determine whether the time has elapsed by sequentially referring to the count value of the timer 21.

[0027] The timer 21's function is not limited to being provided within the control unit 20; it may also be provided outside the control unit 20.

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

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

[0030] Output Pout is output from the fuel cell system 1 by the output power P1 supplied from the fuel cell unit 10 and the power Ps input and output from the energy storage unit 30. The energy storage unit 30 can store (charge) the power of the fuel cell unit 10 after it has started operating, or store power from an external power source (not shown) (for example, an AC power grid). The energy 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 requirements of the external load EX, the surplus power Ps is stored. When the output power P1 of the fuel cell unit 10 is in excess of the requirements 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 energy storage unit 30 (Pout = P1 - Ps).

[0032] Furthermore, if the output power P1 of the fuel cell unit 10 is insufficient to meet the requirements of the external load EX, the insufficient power Ps is discharged. When the output power P1 of the fuel cell unit 10 is insufficient to meet the requirements 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 energy storage unit 30 (Pout = P1 + Ps).

[0033] By including the energy storage unit 30 in the fuel cell system 1, the output Pout from the fuel cell system 1 can be output stably.

[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 "generated water") produced by the chemical reaction between hydrogen and oxygen in the fuel cell stack 11. The gas-liquid separator 40 discharges the generated water EL and the exhaust gas EG from which the liquid component (generated water EL) has been removed from the exhaust gas EC, and the exhaust gas EG and generated 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 water quality of the generated water EL.

[0036] For example, water quality meter 50 detects sulfate ions (SO4) contained in the generated water EL. 2- Information regarding the concentration of ) is obtained. The water quality meter 50 is, for example, an electrical conductivity meter capable of measuring the electrical conductivity of the generated water EL. This is because a certain correlation can be found between the electrical conductivity of the generated water EL and the concentration of sulfate ions contained in the generated water EL.

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

[0038] <Processing in the fuel cell system according to the first embodiment> The processing in the fuel cell system according to the first embodiment will now be described. Figure 2 is a flowchart illustrating the processing in fuel cell system 1, which is an example of a 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 terminates the process.

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

[0041] In step S20, the control unit 20 may introduce hysteresis when determining whether the electrical conductivity of the generated water EL is above a first threshold. The hysteresis is, for example, 1 microsiemen per centimeter (μS / cm).

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

[0043] (Step S30) Next, the control unit 20 determines whether the stack voltage drop is above a predetermined threshold, which is a second threshold. The control unit 20 sends a control command to the control unit 14 of the fuel cell unit 10 to send data regarding 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 to calculate the voltage drop in the stack voltage (stack voltage drop).

[0044] If the stack voltage drop is greater than or equal to the second threshold (YES in step S30), the control unit 20 proceeds to step S40. The second threshold is, for example, a voltage value of 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) If, in step S20, the electrical conductivity is above the first threshold (YES in step S20), and in step S30, the stack voltage drop is above the second threshold (YES in step S30), the control unit 20 stops the operation of the fuel cell unit 10.

[0046] The control unit 20 starts the 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 refers to the timer 21 to determine whether the first time has elapsed. If the first time has elapsed (YES in step S50), the control unit 20 proceeds to 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 one hour has elapsed since the fuel cell unit was stopped (YES in step S50), the control unit 20 starts the fuel cell unit 10.

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

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

[0051] In Figure 3, the horizontal axis represents time, and the vertical axis represents electrical conductivity. Line L1 represents the measurement results of electrical conductivity when an electrical conductivity meter was used as the water quality meter 50. TH1 indicates the threshold. The threshold 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 from time t1. When impurities are mixed in, the electrical conductivity measured by an electrical conductivity meter, which is an example of a water quality meter 50, increases. If the electrical conductivity exceeds the threshold TH1 at time t2, the control unit 20 stops the operation of the fuel cell unit 10.

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

[0054] According to the fuel cell system of the first embodiment, deterioration of the fuel cell unit due to impurities contained in the hydrogen or air used as fuel can be suppressed. According to the fuel cell system of the first embodiment, irreversible deterioration of the fuel cell unit due to the inclusion of impurities can be suppressed. Furthermore, according to the fuel cell system of the first embodiment, operation under conditions where running costs have worsened due to the inclusion of impurities can be avoided.

[0055] If the air supplied to the fuel cell unit temporarily contains impurities such as sulfur-based substances (sulfur or sulfides), bromine-based substances (bromine or bromides), chlorine-based substances (chlorine or chloride), ammonia-based substances (ammonia and its compounds (ammonium compounds)), volatile organic compounds, or metals, these impurities may adhere to the fuel cell catalyst and inhibit the power generation reaction. If the air temporarily contains impurities such as sulfur-based substances (sulfur or sulfides), bromine-based substances (bromine or bromides), chlorine-based substances (chlorine or chloride), ammonia-based substances (ammonia and its compounds (ammonium compounds)), volatile organic compounds, or metals, and adheres to the fuel cell catalyst and inhibits the power generation reaction, the electromotive force of the fuel cell will decrease, which may reduce power generation efficiency and worsen running costs.

[0056] Some of the sulfur, bromine, and chlorine impurities dissolve in the generated water inside the fuel cell, becoming sulfate ions, bromide ions, and chloride ions, respectively, which are then discharged as wastewater. Since the ion concentrations of sulfate, bromide, and chloride ions are positively correlated with electrical conductivity, the presence of impurities can be estimated from the water quality meter readings. If the electrical conductivity exceeds a threshold and impurities are detected, the fuel cell unit is shut down via the control unit.

[0057] Electrical conductivity meters are easy to maintain, allowing for long-term measurements. Furthermore, they can continuously measure with a sampling period of approximately 10 seconds.

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

[0059] ≪Second Embodiment≫ A fuel cell system according to the second embodiment will now be described. The fuel cell system according to the second embodiment comprises a solid polymer fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, a water quality meter that measures the water quality of the water produced when the fuel cell unit generates electricity, and an impurity removal device that removes impurities contained in the oxygen. Furthermore, the fuel cell system according to the second embodiment comprises a control unit that controls the removal of impurities contained in the air by the impurity removal device based on the water quality measured by the water quality meter.

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

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

[0062] The fuel cell system 2 comprises a fuel cell unit 10, a control unit 120, an energy 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 fuel cell system 2, configurations common to fuel cell system 1, which is an example of a fuel cell system according to the first embodiment, will be omitted here, as they are described in the description of fuel cell system 1.

[0064] [Impurity removal device 150] The impurity removal device 150 is installed as a bypass in the flow path that supplies 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 between directing the air supplied from the outside to the flow rate adjustment unit 13 or passing it through the impurity removal device 150 before flowing it to the flow rate adjustment unit 13. The three-way valve 160 is controlled by the control unit 120.

[0066] In the example above, a three-way valve is used, but the same function can be achieved by combining two valves instead of using a 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, a detailed explanation of the control unit 120 is omitted here; please refer to the description of the control unit 20.

[0068] <Processing in the fuel cell system under the second embodiment> The processing in the fuel cell system according to the second embodiment will now be described. Figure 5 is a flowchart illustrating the processing in 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 terminates the process.

[0070] (Step S120) Next, the control unit 120 determines whether the electrical conductivity of the generated water EL is greater than or equal to a first threshold. The control unit 120 controls the water quality meter 50 to measure the electrical conductivity of the generated water EL. The control unit 120 then obtains the electrical conductivity of the generated water EL from the water quality meter 50. The control unit 120 determines whether the electrical conductivity of the generated water EL is greater than or equal to 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 generated water EL is greater than or equal to the first threshold (YES in step S120), the control unit 120 proceeds to step S130. If the electrical conductivity of the generated water EL is less than the first threshold (NO in step S120), the control unit 120 proceeds to step S140.

[0072] In step S120, the control unit 120 may introduce hysteresis when determining whether the electrical conductivity of the generated water EL is above a first threshold. The hysteresis is, for example, 1 microsiemen per centimeter (μS / cm). By introducing 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 stack voltage drop is above a predetermined threshold, which is a second threshold. The control unit 120 sends a control command to the control unit 14 of the fuel cell unit 10 to transmit data regarding the stack voltage. Based on the control command, the control unit 14 transmits the stack voltage to the control unit 120. The control unit 120 compares the previously acquired stack voltage with the currently acquired stack voltage to calculate the voltage drop in the stack voltage (stack voltage drop).

[0074] If the stack voltage drop is greater than or equal to 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 to control the flow so that the air SA flows directly to the flow rate adjustment unit 13. After switching the three-way valve 160 from B to A, the control unit 120 proceeds to 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 flow of air SA 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 cycle has elapsed. The control unit 120 uses the timer 21 to determine whether a predetermined control cycle has elapsed. If the control cycle has elapsed (YES in step S160), the control unit 120 proceeds to step S110. If the control cycle has not elapsed (NO in step S160), the control unit 120 repeats the process in step S160.

[0078] As described above, the control unit 120 controls the flow path of the air SA to switch based on the measurement results measured by the water quality meter 50.

[0079] The operation of the fuel cell system according to the second embodiment will now be described. Figure 6 is a diagram illustrating the operation of fuel cell system 2, which is an example of a fuel cell system according to the second embodiment.

[0080] In Figure 6, the horizontal axis represents time, and the vertical axis represents electrical conductivity. Line L2 shows the measurement results of electrical conductivity when an electrical conductivity meter was used as the water quality meter 50. TH1 indicates the threshold. The threshold 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 from time t11. When 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 the threshold 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 falls below the threshold TH1 (TH1-h, considering hysteresis) 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, by removing impurities contained in the air supplied to the fuel cell unit using an impurity removal device, deterioration of the fuel cell unit due to impurities in the air can be suppressed. 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 suppressed. Furthermore, according to the fuel cell system of the second embodiment, operation under conditions where running costs have worsened due to the inclusion of impurities can be avoided.

[0083] Furthermore, according to the fuel cell system of the second embodiment, even when impurities are temporarily present in the air, the impurities can be removed, allowing the fuel cell unit to continue operating without irreversible deterioration. In addition, according to the fuel cell system of the second embodiment, by not allowing the air to pass through the impurity removal device at all times, but only when impurities are present, the pressure loss of the impurity removal device can be reduced when there are no impurities, and the power of the air compressor can be reduced.

[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 measurement results measured by a water quality meter. For example, in the fuel cell system according to the second embodiment, the system may be controlled to stop the fuel cell unit after initially switching the air flow path a desired number of times.

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

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

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

[0088] The fuel cell system 3 comprises a fuel cell unit 10, a control unit 220, an energy 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 fuel cell system 3, configurations common to fuel cell system 1, which is an example of a fuel cell system according to the first embodiment, will be omitted here, as they are described in the description of fuel cell system 1.

[0090] [Impurity removal device 250] The impurity removal device 250 is installed as a bypass to the flow path that supplies 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 hydrogen SH. The three-way valve 260 switches between directing the hydrogen supplied from the outside to the flow rate adjustment unit 13 or passing it through the impurity removal device 250 before flowing it to the flow rate adjustment unit 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, a detailed explanation of the control unit 220 is omitted; please refer to the description of the control unit 20.

[0093] <Processing in the fuel cell system under the third embodiment> Since the processing in the fuel cell system according to the third embodiment is the same as that in the fuel cell system according to the second embodiment, a detailed explanation will be omitted, and the description of the fuel cell system according to the second embodiment will be provided. The control unit 220 controls the switching of the hydrogen SH flow path based on the measurement results measured by the water quality meter 50, similar to the control unit 120.

[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, an impurity removal device may also be provided on the air supply side, as in the fuel cell system according to the second embodiment.

[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 measurement results measured by a water quality meter. For example, in the fuel cell system according to the third embodiment, the system may be controlled to stop the fuel cell unit after initially switching the hydrogen flow path a desired number of times.

[0097] ≪Fourth Embodiment≫ A fuel cell system according to the fourth embodiment will now be described. The fuel cell system according to the fourth embodiment comprises a solid polymer fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, and a water quality meter that measures the water quality of the generated water produced during power generation by the fuel cell unit. The fuel cell system according to the fourth embodiment also comprises 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] Figure 8 is a schematic diagram showing the configuration of a fuel cell system 4, which is an example of a fuel cell system according to the fourth embodiment.

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

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

[0101] In fuel cell system 4, configurations common to fuel cell system 1, which is an example of a fuel cell system according to the first embodiment, will be omitted here, as they are described in the description of fuel cell system 1.

[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, a detailed explanation of the control unit 320 will be omitted, and details of the control unit 320 should be referred to in the description of the control unit 20.

[0103] <Processing in the fuel cell system according to the fourth embodiment> The processing in the fuel cell system according to the fourth embodiment will now be described. Figure 9 is a flowchart illustrating the processing in 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 terminates the process.

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

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

[0107] In step S220, the control unit 320 may introduce hysteresis when determining whether the electrical conductivity of the generated water EL is above a first threshold. The hysteresis is, for example, 1 microsiemen per centimeter (μS / cm).

[0108] (Step S230) Next, the control unit 320 determines whether the stack voltage drop is above a predetermined threshold, which is a second threshold. The control unit 320 sends a control command to the control unit 14 of the fuel cell unit 10 to send data regarding 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 to calculate the voltage drop in the stack voltage (stack voltage drop).

[0109] If the stack voltage drop is greater than or equal to 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 according to the 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 enhanced refresh operation. Specifically, the control unit 320 controls the refresh operation to perform the refresh process with a shorter refresh cycle (e.g., a 6-hour cycle) than the normal refresh cycle (e.g., a 12-hour cycle). After starting enhanced refresh operation, the control unit 320 proceeds to step S260.

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

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

[0114] In the upper graph of Figure 10, the horizontal axis represents time, and the vertical axis represents electrical conductivity. Line L3 represents the measurement results of electrical conductivity when an electrical conductivity meter was used as the water quality meter 50. TH1 indicates the threshold. The threshold 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 operation is indicated by a white arrow, and enhanced refresh operation is indicated by a black arrow. Normal refresh operation repeats the refresh operation according to a refresh cycle PRD1 (e.g., 12 hours). Enhanced refresh operation repeats the refresh operation according to 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, the electrical conductivity temporarily increases when a refresh operation is performed. This temporary increase in electrical conductivity occurs because impurities attached to the electrodes, etc., dissociate and mix into the generated water EL. Therefore, the measurement results of the water quality meter 50 during the refresh operation should be ignored.

[0118] In Figure 10, assume that impurities are introduced during period TRM1. When the electrical conductivity exceeds the threshold TH1, the control unit 320 intensifies the refresh operation for period TRM2 until the electrical conductivity falls below the threshold TH1 (TH1-h, considering hysteresis h). When the refresh operation is intensified, the control unit 320 sets the refresh cycle to a shorter refresh cycle PRD2 than the normal refresh cycle (refresh cycle PRD1). For example, the control unit 320 performs the refresh operation at half the cycle of the normal refresh operation.

[0119] The control unit 320 switches to normal refresh operation after the electrical conductivity falls below the threshold TH1 (TH1-h, taking hysteresis h into account).

[0120] According to the fuel cell system of the fourth embodiment, the catalyst can be thoroughly cleaned and accumulated impurities discharged by increasing the frequency of stop-restart refresh cycles. This makes it possible to recover from the decrease in electromotive force and power generation efficiency of the fuel cell unit.

[0121] Furthermore, 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, in the fuel cell system according to the fourth embodiment, an impurity removal device may be provided 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 comprises a plurality of fuel cell units.

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

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

[0125] The fuel cell system 5 comprises fuel cell units 410A, 410B, 410C, and 410D, and a control unit 420. Note that in Figure 11, power-related components (e.g., energy storage units, etc.) are omitted. The fuel cell system 5 also comprises gas-liquid separators 440A, 440B, 440C, and 440D, corresponding to fuel cell units 410A, 410B, 410C, and 410D, respectively. Furthermore, the fuel cell system 5 comprises a water quality meter 50, impurity removal devices 450 and 451, and three-way valves 460 and 461.

[0126] In fuel cell system 5, configurations common to fuel cell system 1, which is an example of a fuel cell system according to the first embodiment, will be omitted here, as they are described in the description of fuel cell system 1.

[0127] [Fuel cell unit 410A, fuel cell unit 410B, fuel cell unit 410C, and fuel cell unit 410D] The fuel cell system 5 comprises multiple fuel cell units. While this example of fuel cell system 5 includes four fuel cell units, the number of fuel cell units is not limited to four; two or more units are acceptable. For details regarding the fuel cell units, please refer to the description of fuel cell system 1, which is an example of a fuel cell system according to the first embodiment; a detailed explanation is omitted here.

[0128] [Gas-liquid separator 440A, gas-liquid separator 440B, gas-liquid separator 440C, and gas-liquid separator 440D] The fuel cell system 5 is equipped with multiple gas-liquid separators, each corresponding to one of the multiple fuel cell units. Specifically, the fuel cell system 5 is equipped with 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 gas-liquid separators 440B, 440C, and 440D, corresponding to fuel cell units 410B, 410C, and 410D, respectively. Gas-liquid separators 440B, 440C, and 440D process exhaust gas backbone (ECB), exhaust gas condensate (ECC), and exhaust gas condensate (ECD), respectively.

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

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

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

[0133] [Impure removal device 450 and impurity removal device 451] The impurity removal device 450 is installed as a bypass to the air supply channel SA. The impurity removal device 450 removes impurities contained in the air SA. The impurity removal device 451 is installed as a bypass to the hydrogen supply channel 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 between directing the externally supplied air SA to each of the fuel cell units or passing it through the impurity removal device 450 before flowing it to each of the 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 hydrogen SH. The three-way valve 461 switches between directing the hydrogen SH supplied from the outside to each of the fuel cell units, or passing it through the impurity removal device 451 before flowing it to each of the fuel cell units. The three-way valve 461 is controlled by the control unit 420.

[0136] [Control Unit 420] The control unit 420 controls fuel cell units 410A, 410B, 410C, and 410D, respectively. The control unit 420 also controls the three-way valves 460 and 461. Since the control unit 420 has the same hardware configuration as the control unit 20, a detailed explanation of the control unit 420 is omitted here; please refer to the description of the control unit 20.

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

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

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

[0140] Figure 12 is a schematic diagram of the configuration of a fuel cell system 6, which is an example of a fuel cell system according to the sixth embodiment. The fuel cell system 6 is equipped with a gas-liquid separator 540 in place of the gas-liquid separators 440A, 440B, 440C, and 440D in the fuel cell system 5, which is an example of a fuel cell system according to the fifth embodiment.

[0141] In fuel cell system 6, configurations common to fuel cell system 5, which is an example of a fuel cell system according to the fifth embodiment, will be omitted here, as they should be referred to in the description of fuel cell system 5.

[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 gases ECA, ECB, ECC, and ECD discharged from the multiple fuel cell units. The gas-liquid separator 540 separates the gases into exhaust gas EG and generated water EL and discharges them to the outside. The generated water EL is generated water collected from the generated water discharged from the multiple fuel cell units.

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

[0144] ≪Seventh Embodiment≫ A fuel cell system according to the seventh embodiment will now be described. The fuel cell system according to the seventh embodiment includes a solid polymer 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 for measuring the water quality of the generated water on the air side produced during power generation by the fuel cell unit, and a first impurity removal device for removing impurities contained in the air. Furthermore, the fuel cell system according to the seventh embodiment includes a second water quality meter for measuring the water quality of the generated water on the fuel electrode side produced during power generation by the fuel cell unit, and a second impurity removal device for removing impurities contained in hydrogen. Furthermore, the fuel cell system according to the seventh embodiment 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. Furthermore, the control unit in the fuel cell system according to the seventh embodiment controls the second impurity removal device to remove impurities contained in hydrogen based on the water quality measured by the second water quality meter.

[0145] Figure 13 is a schematic diagram showing 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 cell cells. The fuel cell system 7 is a chemical battery that converts chemical energy into electricity by reacting hydrogen with oxygen in the air. The fuel cell system 7 supplies output Pout to an external load EX.

[0147] The fuel cell system 7 comprises a fuel cell unit 710, a control unit 720, an energy storage unit 30, a gas-liquid separator 740a and a gas-liquid separator 740h, and a water quality meter 50a and a water quality meter 50h. The fuel cell system 7 also comprises 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 components common to the fuel cell system 1, which is an example of a fuel cell system according to the first embodiment, please refer to the description in the fuel cell system 1, and a detailed explanation will be omitted here.

[0149] [Fuel cell unit 710] The fuel cell unit 710 replaces the fuel cell stack 11 in the fuel cell unit 10 with a fuel cell stack 711. 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 the exhaust from the air electrode side and the exhaust from the fuel electrode side. The fuel cell stack 711 differs from the fuel cell stack 11 in that it discharges the exhaust from the air electrode side and the exhaust 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 it discharges the exhaust from the air electrode side and the exhaust 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 gas ECa. The gas-liquid separator 740a discharges the generated water ELa and exhaust gas ECa from which the liquid components (generated water ELa) have been removed, and the exhaust gas ECa and generated water ELa are discharged outside the fuel cell system 7. The gas-liquid separator 740h separates the liquid components contained in the exhaust gas ECh. The gas-liquid separator 740h discharges the generated water ELh and exhaust gas ECh from which the liquid components (generated water ELh) have been removed, and the exhaust gas ECh and generated water ELh are discharged outside the fuel cell system 7.

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

[0152] [Impurity removal device 750a and impurity removal device 750h] The impurity removal device 750a is installed as a bypass to the air supply channel SA. The impurity removal device 750a removes impurities contained in the air SA. In addition, the impurity removal device 750h is installed as a bypass to the hydrogen supply channel 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 air SA. The three-way valve 760a switches whether the air supplied from the outside flows directly to the flow rate adjustment unit 13 or passes through the impurity removal device 750a before flowing to the flow rate adjustment unit 13. The three-way valve 760a is controlled by the control unit 720. The three-way valve 760h switches the flow path of hydrogen SH. The three-way valve 760h switches whether the hydrogen supplied from the outside flows directly to the flow rate adjustment unit 13 or passes through the impurity removal device 750h before flowing to the flow rate adjustment unit 13. The three-way valve 760h is controlled by the control unit 720.

[0154] In the example above, a three-way valve is used, but the same function can be achieved by combining two valves instead of using a three-way valve.

[0155] [Control Unit 720] The control unit 720 controls the fuel cell unit 710. The control unit 720 also controls the three-way valves 760a and 760h, respectively. For example, if the control unit 720 determines that the water quality of the generated water ELa, as measured by the water quality meter 50a, is poor, it controls the three-way valve 760a to switch the water to flow to the impurity removal device 750a. Similarly, if the control unit 720 determines that the water quality of the generated water ELa, as measured by the water quality meter 50h, is poor, it controls the three-way valve 760h to switch the water to flow to the impurity removal device 750h.

[0156] For specific control details, please refer to the description of the fuel cell system according to the second or third embodiment; a detailed explanation is 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 impurities contained in the air or hydrogen, deterioration of the fuel cell unit due to impurities contained in the air or hydrogen can be suppressed.

[0158] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The above embodiments may be omitted, replaced, 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 systems 10, 410A, 410B, 410C, 410D, 710 Fuel Cell Units 20, 120, 220, 320, 420, 720 control units 30 Energy Storage Units 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, EGh exhaust EL, ELa, ELh produced water SA, SAs air SH, SHs Hydrogen TH1 threshold

Claims

1. A solid polymer fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, A water quality meter for measuring the water quality of the water generated during power generation by the fuel cell unit, A control unit that controls the fuel cell unit based on the water quality measured by the water quality meter, Equipped with, Fuel cell system.

2. A solid polymer fuel cell unit that generates electricity by chemically reacting hydrogen and oxygen, A water quality meter for measuring the water quality of the water generated during power generation by the fuel cell unit, An impurity removal device for removing impurities contained in at least one of the hydrogen and oxygen-containing air, A control unit controls the removal of impurities contained in at least one of the hydrogen and the air by the impurity removal device based on the water quality measured by the water quality meter, Equipped with, Fuel cell system.

3. The flow path through which the hydrogen or oxygen is supplied is provided with a valve that switches the flow path between directly supplying the hydrogen or oxygen to the fuel cell unit or passing it through the impurity removal device and then directly supplying it 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 2.

4. The aforementioned impurities are any of the following: sulfur, sulfide, bromine, bromide, chlorine, chloride, ammonia, ammonium compounds, volatile organic compounds, or metals. The fuel cell system according to claim 2.

5. The control unit controls the fuel cell unit to shut down if the electrical conductivity measured by the water quality meter is equal to or greater than a first threshold. A fuel cell system according to any one of claims 1 to 4.

6. The control unit controls the fuel cell unit to enhance the 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. A fuel cell system according to any one of claims 1 to 4.

7. A plurality of the aforementioned fuel cell units are provided. A fuel cell system according to any one of claims 1 to 4.

8. The water quality meter measures the water quality of the generated water collected from each of the multiple fuel cell units. The fuel cell system according to claim 7.

9. Each of the multiple fuel cell units is equipped with a gas-liquid separator to which it is connected. The fuel cell system according to claim 7.

10. The aforementioned hydrogen is a by-product hydrogen. A fuel cell system according to any one of claims 1 to 4.

11. The hydrogen mentioned above is crude hydrogen produced from a hydrogen production device. A fuel cell system according to any one of claims 1 to 4.

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