JP2008021500A - Fuel cell system - Google Patents

Abstract

Provided is a fuel cell system capable of suppressing the detection accuracy of a sensor disposed on a flow path of an oxidant gas from being deteriorated due to the influence of impurities or the deterioration of the sensor.
An oxidant gas flow path that passes through an air electrode of a fuel cell, a plurality of sensors provided in the oxidant gas flow path, and an oxidant gas flow path disposed upstream of the plurality of sensors in the oxidant gas flow path A fuel cell system including a chemical filter that adsorbs impurities contained in the agent gas. According to the present invention, since the impurities are removed by the chemical filter, it is possible to suppress the action of the impurities on each of the plurality of sensors arranged on the downstream side, and to maintain the accuracy of the sensor.
[Selection] Figure 1

Description

  The present invention relates to a fuel cell system.

In order to remove impurity components harmful to the fuel cell such as sulfur compounds (for example, SO ₂ and H ₂ S) and nitrogen oxide (NOx) from the air supplied as the oxidant gas to the air electrode of the fuel cell, There is one in which a chemical filter is disposed on a supply path of an oxidant gas to a fuel cell (for example, Patent Document 1). The chemical filter is made of activated carbon or the like, and removes impurity components by adsorbing them.
JP-A-2005-116353

  In general, various sensors such as a pressure sensor and a temperature sensor provided to adjust the supply amount of the oxidant gas to the fuel cell and its temperature are provided on the supply path of the oxidant gas.

  Conventionally, there is no example of arranging a chemical filter in consideration of the relationship with various sensors arranged in the oxidant gas supply path, and a sensor such as a pressure sensor or a temperature sensor may be arranged upstream of the chemical filter. there were.

In this case, the sensor disposed on the upstream side of the chemical filter is exposed to an impurity component (for example, SO ₂ or H ₂ S) contained in the oxidant gas for a long time, and the impurities adhere to the sensor, thereby improving the detection accuracy of the sensor. There was a risk of lowering. In addition, the moisture contained in the oxidant gas may act on impurities attached to the sensor to generate acid, which may corrode the sensor.

  An object of the present invention is to provide a fuel cell system capable of suppressing the detection accuracy of a sensor disposed on a flow path of an oxidant gas from being deteriorated due to the influence of impurities, or deterioration of the sensor. It is.

  The present invention employs the following configuration in order to solve the above-described problems.

That is, the present invention provides an oxidant gas flow path for introducing an oxidant gas into a cathode electrode of a fuel cell and exhausting an exhaust gas from the cathode electrode;
A plurality of sensors provided on the oxidant gas flow path;
The fuel cell system includes an adsorber including a chemical filter that is disposed upstream of the plurality of sensors in the oxidant gas flow path and adsorbs impurities contained in the oxidant gas.

  According to the present invention, since impurities are removed by the chemical filter, it is possible to suppress the action of impurities on each of the plurality of sensors arranged on the downstream side, and to maintain sensor accuracy and prevent sensor corrosion. Can do.

  Preferably, the fuel cell system according to the present invention further includes a dust filter disposed on the upstream side of the chemical filter in the oxidant gas flow path.

  In this case, since the particulate matter contained in the oxidant gas can be removed by the dust filter, the influence of the particulate matter on the sensor can be reduced. Moreover, when the oxidant gas passes through the dust filter, the moisture in the oxidant gas reaching the chemical filter can be reduced, and the moisture can be prevented from affecting the chemical filter.

Preferably, the fuel cell system according to the present invention comprises a measuring means for measuring the amount of oxidant gas that has passed through the adsorber,
A concentration sensor that detects the concentration of the impurities contained in the oxidant gas that has passed through the adsorber;
Estimating means for estimating the amount of the impurity adsorbed on the chemical filter based on the measured amount of the oxidant gas, the detected concentration, and a ratio determined from the adsorption efficiency of the chemical filter;
Output control means for outputting an alarm when the accumulated value of the amount of impurities exceeds a predetermined value;

  In this way, an alarm is output when the amount of impurities adsorbed on the chemical filter reaches a predetermined value, so that, for example, it is possible to notify the outside that the chemical filter has reached the end of its life.

  According to the present invention, it is possible to provide a fuel cell system capable of suppressing the detection accuracy of a sensor disposed on a flow path of an oxidant gas from being lowered due to the influence of impurities or the sensor from being deteriorated. Can do.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configuration of the embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.

  FIG. 1 is a diagram illustrating a configuration example of a fuel cell system according to an embodiment of the present invention. This fuel cell system is mounted on a moving body (for example, a vehicle). As the fuel cell 1 in FIG. 1, a polymer electrolyte fuel cell (PEFC) is applied. The fuel cell 1 is composed of a cell stack formed by stacking a plurality of cells (however, FIG. 1 schematically shows the configuration of a single cell in the fuel cell 1).

  The cell sandwiches the solid polymer electrolyte membrane 2, the fuel electrode (anode) 3 and the air electrode (oxidizer electrode: cathode electrode) 4 that sandwich the solid polymer electrolyte membrane 2 from both sides, and the fuel electrode 3 and air electrode 4. It consists of a fuel electrode side separator 5 and an air electrode side separator 6.

  The fuel electrode 3 has a diffusion layer and a catalyst layer. A fuel (fuel gas) containing hydrogen such as hydrogen gas or hydrogen rich gas is supplied to the fuel electrode 3 by a fuel supply system. The fuel gas supplied to the fuel electrode 3 is diffused in the diffusion layer and reaches the catalyst layer. In the catalyst layer, hydrogen in the fuel gas is separated into protons (hydrogen ions) and electrons. Hydrogen ions move to the air electrode 4 through the solid polymer electrolyte membrane 2, and electrons move to the air electrode 4 through an external circuit (not shown).

  On the other hand, the air electrode 4 has a diffusion layer and a catalyst layer. An oxidant gas such as air is supplied to the air electrode 4 by an oxidant supply system. The oxidant gas supplied to the air electrode 4 is diffused in the diffusion layer and reaches the catalyst layer. In the catalyst layer, water is generated through a reaction between the oxidant gas, hydrogen ions that have reached the air electrode 4 through the solid polymer electrolyte membrane 2, and electrons that have reached the air electrode 4 through an external circuit.

  The electrons passing through the external circuit during the reaction at the fuel electrode 3 and the air electrode 4 as described above are used as electric power for the load connected between both terminals of the fuel cell 1.

  FIG. 1 shows an oxidant gas flow path that passes through the air electrode 4 of the fuel cell 1. The oxidant gas flow path includes an air electrode 4 of the fuel cell 1, an oxidant supply system provided on the upstream side of the air electrode 4, and an oxidant discharge system provided on the downstream side of the air electrode 4. The

In FIG. 1, the oxidant supply system includes a dust filter 12 into which outside air (air) taken in from an air intake pipe 11 is introduced, and a chemical filter 13 disposed on the downstream side of the dust filter 12. The inlet of the air intake pipe 11 is disposed so as to open toward the outside air intake provided in the vehicle. In the air introduced into the air intake pipe 11, impurity components (sulfur compounds (eg, SO ₂ and H ₂ S), nitrogen compounds, etc.) are gas (gas), liquid, solid (granular, powder). Included in the state.

The dust filter 12 removes particulate matter in the air. The chemical filter 13 is made of activated carbon or the like, and removes impurity components (sulfur compounds (eg, SO ₂ and H ₂ S), nitrogen compounds, etc.) contained in the air by adsorbing them.

  The dust filter 12 and the chemical filter 13 are configured as one unit having both. In the example shown in FIG. 1, the dust filter 12 and the chemical filter 13 are accommodated in an accommodation container 13A joined so that the air intake pipe 11 and the pipe 14 communicate with each other. The air introduced into 13 </ b> A passes through the chemical filter 13 after passing through the dust filter 12, and is sent out into the pipe 14. The storage container 13A functions as an adsorber that stores a chemical filter.

  In the container 13A, the dust filter 12 and the chemical filter 13 may be disposed in contact with each other, or may be disposed with a distance therebetween. Moreover, you may make it arrange | position the dust filter 12 and the chemical filter 13 in a different container. In this case, the two storage containers may be formed integrally and the internal spaces of the storage containers may be communicated with each other, or the internal spaces of the storage containers may be configured to communicate with the internal space of the pipe. good.

  The air that has passed through the chemical filter 13 is sucked into the air flow meter 15 connected to the pipe 14 via the pipe 14. The pipe 14 is provided with a pressure sensor 16 that detects the pressure (air pressure) in the pipe 14 and a temperature sensor 17 that detects the temperature in the pipe 14. Further, the pipe 14 is provided with a concentration sensor 18 that detects the concentration of a specific impurity component contained in the air that has passed through the chemical filter 13.

  The air flow meter 15 measures the amount of intake air (the amount of air passing through itself). The air that has passed through the air flow meter 15 is introduced into an air pump (air compressor) 20 connected through a pipe 19. The air pump 20 operates by driving the motor 21 and sends air to the fuel cell 1 side. The air pump 20 is connected to the intercooler 23 through the pipe 22, and the air sent out from the air pump 20 is introduced into the intercooler 23 through the pipe 22. The pipe 22 is provided with a temperature sensor 24 that detects the temperature in the pipe 22 (the temperature of the air flowing through the pipe 22).

The intercooler 23 cools the air introduced therein and discharges it to the pipe 25. The pipe 25 is connected to the oxidant gas inlet of the fuel cell 1. The pipe 25 is provided with a temperature sensor 26 that detects the temperature in the pipe 25 (the temperature of the air discharged from the intercooler 23). The air introduced into the oxidant gas inlet diffuses into the air electrode 4 through a flow path provided in the air electrode side separator 6. The air that has passed through the air electrode 4 is discharged as an exhaust gas from the oxidant gas outlet of the fuel cell 1 to the outside.

  In FIG. 1, the oxidant discharge system is configured as follows. A pipe 27 is connected to the oxidant gas outlet of the fuel cell 1, and the pipe 27 is connected to a regulator (back pressure adjusting valve) 28. The pipe 27 is provided with a pressure sensor 29 that detects the pressure in the pipe 27. The regulator 28 adjusts the back pressure of the air pump 20 by changing the opening of the valve. A muffler 31 is connected to the regulator 28 via a pipe 30, and the air that has passed through the muffler 31 is discharged into the outside air.

  The fuel cell system includes an ECU (Electronic Control Unit: computer) 32 as a control system (control means) for controlling the above-described oxidant supply system and oxidant discharge system. The ECU 32 is a processor such as a CPU (Central Processing Unit), a program executed by the processor, a memory (storage device) that stores data used in executing the program, an input / output interface (I / O) with a sensor, and the like. ) Etc.

  The ECU 32 receives output signals from the air flow meter 15, the pressure sensor 16, the temperature sensor 17, the concentration sensor 18, the temperature sensor 24, the temperature sensor 26, and the pressure sensor 29 described above. The ECU 32 controls the operation of the air pump 20, the air cooling ability by the intercooler 23, and the opening degree of the regulator 28 based on the output signals from the air flow meter 15 and each sensor by the CPU executing a program stored in the memory. To do.

  The ECU 32 measures the amount of oxidant gas (air) supplied to the fuel cell using the output signal from the air flow meter 15 and the sensor output signals from the pressure sensor 16 and the temperature sensor 17. That is, the air flow meter 15 gives an electric signal corresponding to the intake air amount to the ECU 32 as an output signal. The electric signal given at this time indicates the amount of air under atmospheric pressure and temperature conditions as predetermined standards. On the other hand, the density of air depends on pressure and temperature. Therefore, the ECU 32 corrects the amount of air obtained from the air flow meter 15 with the pressure and temperature received from the pressure sensor 16 and the temperature sensor 17. In this way, the ECU 32 measures an accurate air amount. The measured air amount is used, for example, for controlling the amount of air supplied to the fuel cell 1 by the air pump 20.

  The ECU 32 controls the operation of the air pump 20 using an output signal from the temperature sensor 24 (temperature in the pipe 22). That is, the ECU 32 monitors the temperature of the air discharged (discharged) from the air pump 20 using the output signal from the temperature sensor 24. When the temperature of the exhaust air becomes equal to or higher than a predetermined value, it means that an excessive load is applied to the air pump 20, and if such a state continues, the air pump 20 may break down. For this reason, when the temperature becomes equal to or higher than a predetermined value, the ECU 32 gives a control signal to the motor 21 to reduce the amount of rotation of the air pump 20 or stop the operation of the air pump 20.

  The ECU 32 controls the cooling capacity of the intercooler 23 using an output signal from the temperature sensor 26 (temperature in the pipe 25). The operating temperature of the fuel cell 1 suitable for power generation is determined, and if the fuel cell 1 is heated more than necessary by the air supplied to the fuel cell 1, there is a possibility that proper power generation of the fuel cell 1 may be hindered. For example, when the temperature of the air discharged from the intercooler 23 exceeds a predetermined value, the ECU 32 gives a control signal to the intercooler 23 to increase the cooling capacity of the intercooler 23, and air below the predetermined value is supplied to the fuel cell 1. Like that. For example, if the intercooler 23 is air-cooled, the rotation amount of the fan included in the intercooler 23 is increased by a control signal, the flow rate of cooling air by the fan is increased, and the heat radiation of the air (oxidant gas) passing through the intercooler 23 is increased. To be promoted.

  Further, the ECU 32 controls the opening degree (back pressure) of the regulator 28 using an output signal from the pressure sensor 29 (pressure in the pipe 27). For example, the ECU 32 monitors the pressure in the pipe 27 received from the pressure sensor 29, and when the pressure (back pressure) exceeds a predetermined value (upper limit value), it gives a control signal to the regulator 28 to increase its opening degree. Reduce back pressure. Alternatively, when the pressure falls below a predetermined value (lower limit value), the ECU 32 gives a control signal to the regulator 28 to reduce its opening and increase the back pressure. The ECU 32 performs the back pressure control as described above according to the power generation amount of the fuel cell 1 so that proper operation is performed.

  Furthermore, the fuel cell system shown in FIG. 1 has a configuration that detects the life of the chemical filter 13 and outputs an alarm. That is, the ECU 32 detects the amount of air obtained from the output signals of the air flow meter 15, the pressure sensor 16 and the temperature sensor 17, the concentration of impurity components in the air in the pipe 14 obtained by the concentration sensor 18, and the trap of the chemical filter 13. Based on the ratio obtained from the efficiency (adsorption efficiency), the accumulated amount (accumulated amount) of the impurity component adsorbed on the chemical filter 13 is estimated (calculated), and when this accumulated amount exceeds a predetermined value, the chemical filter An alarm is output on the assumption that 13 lives (replacement time) have come.

  FIG. 2 is a flowchart showing the life determination process of the chemical filter 13 realized by executing a program in the ECU 32. The process shown in FIG. 2 can be started when the operation of the air pump 20 is turned on, for example.

  As preconditions for the following processing, the air amount, pressure, temperature, and concentration based on the output signals from the air flow meter 15 and the sensors 16, 17, 18 are air amount data, pressure data, temperature data, and concentration. Data is recorded (stored) in memory as needed. In the following steps, the ECU 32 reads necessary data from the memory, and calculates Q1, T1, P1, and G1, which will be described later, in time synchronization. That is, there is a time lag between the measurement and recording of air volume, temperature, pressure, and concentration and the calculations described in the following steps.

  When the process is started, the ECU 32 takes in an output signal (air flow meter signal: air amount data) of the air flow meter 15 and obtains an intake air amount Q1 per unit time (step S1). The intake air amount Q1 is stored in a work area of a memory included in the ECU 32.

  Next, the ECU 32 takes in an output signal (air temperature signal: temperature data) from the temperature sensor 17 and obtains an air temperature T1 of the air amount Q1 obtained in step S1 (step S2). The air temperature T1 is stored in a work area of a memory included in the ECU 32.

  Next, the ECU 32 takes in an output signal (air pressure signal: pressure data) from the pressure sensor 16 and obtains the air pressure (air pressure) P1 of the air amount Q1 obtained in step S1 (step S3). The air pressure P1 is stored in a work area of a memory included in the ECU 32.

  Next, the ECU 32 takes in an output signal (concentration signal: concentration data) from the concentration sensor 18 and certain impurities (referred to as impurity X) contained in the air of the air amount Q1 obtained in step S1. Concentration G1 is obtained (step S4). The concentration G1 is stored in a work area of a memory included in the ECU 32.

  Next, the ECU 32 performs air flow rate correction calculation (step S5). That is, the ECU 32 calculates an intake air amount (air flow rate: correction value) Q2 obtained by correcting the intake air amount Q1 stored in the work area with the air temperature T1 and the air pressure P1 stored in the work area, and the work area To store.

  Next, the ECU 32 calculates a passing impurity amount (step S6). That is, the ECU 32 multiplies the intake air amount Q2 stored in the work area and the concentration G1, thereby passing through the chemical filter 13 and passing through the chemical filter 13 into the pipe 14. The amount of impurity X that has reached is calculated as a passing impurity amount G2 and stored in the work area.

  Next, the ECU 32 calculates the accumulated amount of passing impurities (step S7). That is, the ECU 32 reads the value of the accumulated amount of passing impurities G3 stored in the nonvolatile memory (storage means) included in the ECU 32, and adds the amount of passing impurities G2 stored in the work area to the value of G3. Then, a new accumulated amount of passing impurities G3 is calculated, and the new accumulated amount of passing impurities G3 is stored in the nonvolatile memory (overwriting the value of G3) and is also stored in the work area.

  The value of the accumulated amount of passing impurities G3 stored in the non-volatile memory is configured to be set to zero when an unused chemical filter 13 is newly set, and the process of step S7 is executed. Each time, the passing impurity amount G2 is added to the value of G3. As described above, the passing impurity accumulation amount G3 indicates the accumulation amount of the impurity X that has passed through the storage container 13A (adsorber) while the same chemical filter 13 is being used.

  Next, the ECU 32 calculates the trap impurity accumulation amount (step S8). Here, the trap efficiency with respect to the impurity X by the chemical filter 13, that is, the ratio at which the chemical filter 13 is adsorbed when a certain amount of the impurity X passes through the container 13A, is obtained in advance by experiments or the like. From this trap efficiency, the amount of impurity X adsorbed (trapped) by the chemical filter 13 when a certain amount of impurity X passes through the storage container 13A (referred to as M) and the storage container 13A without being trapped. The ratio (M: N) to the amount of impurities X passing through (N) is obtained.

  On the non-volatile memory (storage means) included in the ECU 32, for example, the value of M when the value of N is 1 is stored in advance. The ECU 32 reads the value of M from the non-volatile memory, and multiplies the passage impurity accumulation amount G3 (calculates the ratio), whereby the trap impurity accumulation amount G4 with respect to the passage impurity accumulation amount G3 (adsorbed by the chemical filter 13). The amount of impurity X) is calculated and stored in the work area. Thus, the trap impurity accumulation amount G4 is obtained based on the trap efficiency.

  Next, the ECU 32 performs filter life determination (step S9). That is, the ECU 32 determines whether or not the trap impurity accumulation amount G4 stored in the work area is equal to or less than a predetermined value (determination value G0) stored in advance in the nonvolatile memory. The determination value G0 indicates the cumulative amount of trapped impurities that can be determined that the chemical filter 13 defined through experiments or the like has expired.

  If the trap impurity accumulation amount G4 is equal to or less than the determination value G0 (S9; YES), the process proceeds to step S11. On the other hand, when the trap impurity accumulation amount G4 exceeds the determination value G0 (S9; NO), the ECU 32 performs an alarm output process (step S10).

  For example, as shown in FIG. 1, a warning lamp 33 is connected to the ECU 32. The warning lamp 33 is turned off when the accumulated trap impurity amount G4 is equal to or less than the determination value G0. In step S <b> 10, the ECU 32 gives a lighting signal to the warning lamp 33 to turn on the warning lamp 33. In this manner, the ECU 32 can output an alarm to notify the user (vehicle user) of the fuel cell system that the chemical filter 13 has reached the end of life (it is time to replace it).

Once the warning lamp 33 is turned on, the warning lamp 33 remains on (except for the power-off state) unless a special operation such as a turn-off switch operation by the user is performed. Step S1
When 0 ends, the process returns to step S1.

  On the other hand, when the process proceeds to step S11, the ECU 32 determines whether the air pump 20 is off. When the air pump 20 is on (S11; NO), the process returns to step S1, and when it is off (S11; YES), the life determination process ends.

  In the fuel cell system according to the present embodiment, the chemical filter 13 includes a plurality of sensors (a pressure sensor 16, a temperature sensor 17, and the like) that constitute an oxidant supply system and an oxidant discharge system (arranged in the oxidant gas flow path). The concentration sensor 18, the temperature sensor 24, the temperature sensor 26, and the pressure sensor 29) are disposed upstream of all of them. Thereby, since the impurity component contained in the air is removed by the chemical filter 13, it is prevented that the impurity component adheres to each sensor and affects the measurement accuracy. Further, since the chemical filter 13 is provided on the upstream side of the air flow meter 15, it is possible to suppress the impurity component from affecting the intake air amount detection of the air flow meter 15.

  A dust filter 12 is provided on the upstream side of the chemical filter 13. Since the particulate matter in the air is removed by the dust filter 12, it is possible to suppress the particulate matter from affecting the measurement accuracy of each sensor and the air flow meter 15. Further, since the dust filter 12 is arranged on the upstream side of the chemical filter 13, moisture in the air stays in the dust filter 12, so that the chemical filter 13 is more than the case where the chemical filter 13 is directly connected to the air intake pipe 11. The amount of moisture introduced into 13 is reduced. Thereby, it is possible to suppress the moisture from affecting the adsorption function of the chemical filter 13. Further, since the amount of moisture discharged downstream of the chemical filter 13 is reduced, the moisture in the air acts on the impurities attached to the sensor and the air flow meter 15 to generate an acid, and this acid is generated by the sensor and the air flow meter. 15 can be prevented from corroding.

  Furthermore, according to the present embodiment, the air flow meter 15 functions as a measurement unit, the concentration sensor 18 functions as a detection unit, and the ECU 32 functions as an estimation unit and an output control unit. It is well estimated and can give an alarm at the right time.

  In the process shown in FIG. 2, the order of steps S1, S2, S3, and S4 is arbitrary. In addition, the concentration sensor 18 is prepared for each type of impurity for which the cumulative amount is to be calculated. However, when a plurality of types of impurities can be shared by a single concentration sensor, the concentration of the plurality of types of impurities is detected by a single concentration sensor. The process shown in FIG. 2 can be configured to be executed in parallel for each type of impurity.

  Further, instead of the warning lamp 33, a display device may be prepared so that the display device indicates that the life (replacement time) has come. Further, instead of or in addition to the warning lamp 33 and the display device, the ECU 32 may cause the warning buzzer or the like to output a sound (alarm sound).

  Alternatively, instead of the configuration in which the chemical filter 13 is replaced according to the life, heating means such as a heater is provided around the chemical filter 13, and the ECU 32 controls the operation of the heating means so that the chemical filter 13 is heated and regenerated. May be performed.

  Further, the fuel cell system according to the present invention can be applied not only to a vehicle but also to a fuel cell that is fixedly mounted. The type of fuel cell is not limited to PEFC.

FIG. 1 is a diagram illustrating a configuration example of a fuel cell system according to an embodiment of the present invention. FIG. 2 is a flowchart showing an example of chemical filter life determination processing by the ECU.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 2 ... Solid polymer electrolyte membrane 3 ... Fuel electrode 4 ... Air electrode 5 ... Fuel electrode side separator 6 ... Air electrode side separator 11 ... Air intake pipe 12 ... Dust filter 13 ... Chemical filter 14, 19, 22, 25, 27, 30 ... Piping 15 ... Air flow meter 16, 29 ... Pressure sensors 17, 24, 26 ... Temperature Sensor 18 ... Concentration sensor 20 ... Air pump 21 ... Motor 23 ... Intercooler 28 ... Regulator 31 ... Muffler 32 ... ECU
33 ... Warning light

Claims (3)

An oxidant gas flow path for introducing an oxidant gas into the cathode electrode of the fuel cell and exhausting the exhaust gas from the cathode electrode;
A plurality of sensors provided on the oxidant gas flow path;
A fuel cell system including an adsorber including a chemical filter that is disposed upstream of the plurality of sensors in the oxidant gas flow path and adsorbs impurities contained in the oxidant gas. The fuel cell system according to claim 1, further comprising a dust filter disposed upstream of the chemical filter in the oxidant gas flow path. Measuring means for measuring the amount of oxidant gas that has passed through the adsorber;
A concentration sensor that detects the concentration of the impurities contained in the oxidant gas that has passed through the adsorber;
Estimating means for estimating the amount of the impurity adsorbed on the chemical filter based on the measured amount of the oxidant gas, the detected concentration, and a ratio determined from the adsorption efficiency of the chemical filter;
3. The fuel cell system according to claim 1, further comprising output control means for outputting an alarm when the accumulated value of the amount of impurities exceeds a predetermined value.

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