JP2005158543A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dilute a fuel gas accumulated in a pure water tank, and to exhaust the gas to the outside. <P>SOLUTION: The fuel cell system comprises a hydrogen gas flowing path 1a to which hydrogen gas is supplied, an air flowing path 1b to which compressed air is supplied, and a pure water circulation path 1c through which pure water passes. When a fuel cell stack 1, which has a composition with a possibility that hydrogen mixes into the pure water in the pure water circulation path 1c from the hydrogen gas flowing path 1a, generates electric power, the hydrogen gas is supplied to the hydrogen gas flowing path 1a, and the compressed air is supplied to the air flowing path 1b through an air supply piping L4 connecting the air flowing path 1b to an air supply device 16. Then, in the fuel cell system, the compressed air is guided into a pure water tank 20 through an air guide piping L8 branched from the air supply piping L4 between a heat exchanger 17 and a humidification device 18, and the gas in the pure water tank 20 is exhausted through a ventilation piping L9 to the outside of the pure water tank 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system in which an oxidant gas and a fuel gas are supplied to a fuel cell to generate power, and water is circulated in the fuel cell.

2. Description of the Related Art Conventionally, a fuel cell system that supplies oxidant gas and fuel gas to an oxidant electrode and a fuel electrode of a fuel cell stack and supplies pure water to a water passage provided in the fuel cell stack is known.
Japanese National Patent Publication No. 11-508726

  However, since the conventional fuel cell system described above uses a fuel cell stack that circulates oxidant gas, fuel gas, and water inside the fuel cell stack, the fuel gas enters the water passage from the fuel electrode. Thus, there is a possibility that the fuel gas dissolves in the water and is released in the pure water tank storing the water. As a result, in the conventional fuel cell system, there is a possibility that fuel gas such as hydrogen accumulates in the pure water tank, but there is currently no mechanism for discharging the fuel gas accumulated in the pure water tank. It was.

  Therefore, the present invention has been proposed in view of the above-described circumstances, and an object thereof is to provide a fuel cell system capable of diluting the fuel gas accumulated in the pure water tank and discharging it to the outside.

  In the fuel cell system according to the present invention, when a fuel cell including a fuel electrode to which fuel gas is supplied, an oxidant electrode to which oxidant gas is supplied, and a water passage through which water passes is generated, the fuel cell The fuel gas is supplied to the fuel electrode, and the oxidant gas is supplied to the oxidant electrode of the fuel cell through an oxidant gas supply pipe connecting the oxidant gas compression device and the oxidant electrode of the fuel cell. At this time, in the fuel cell system, the oxidant gas is introduced into the water tank that stores the water supplied to the water flow path of the fuel cell via the oxidant gas introduction pipe branched from the pipe through which the oxidant gas flows. By discharging the gas in the water tank to the outside of the water tank through the gas discharge pipe, the above-described problem is solved.

  According to the fuel cell system of the present invention, the oxidant gas is introduced into the water tank. Therefore, even when the fuel gas is mixed into the water and the fuel gas accumulates in the water tank, Fuel gas can be diluted with oxidant gas and discharged, and the inside of the water tank can be ventilated.

  Hereinafter, first to third embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
The present invention is applied to the fuel cell system according to the first embodiment configured as shown in FIG. 1, for example.

[Configuration of fuel cell system]
This fuel cell system is mounted on, for example, a vehicle, causes the fuel cell stack 1 to perform a power generation reaction, and supplies the generated power generated by the fuel cell stack 1 to a load, thereby generating a running torque of the vehicle.

The fuel cell stack 1 generates power by supplying a fuel gas containing a large amount of hydrogen for generating a power generation reaction and an oxidant gas containing oxygen. The fuel cell stack 1 includes, for example, a fuel electrode (hydrogen electrode) supplied with hydrogen as a fuel gas and an oxidant electrode (air electrode) supplied with air as an oxidant gas with a solid polymer electrolyte membrane interposed therebetween. Is formed by stacking a plurality of the fuel battery cells. That is, in the power generation by the fuel cell stack 1, hydrogen releases electrons at the fuel electrode and ionizes, and the generated hydrogen ions (H ⁺ ) pass through the polymer electrolyte membrane and reach the oxidant electrode. This hydrogen ion is combined with oxygen at the oxidizer electrode to produce water (H ₂ O). In such a fuel cell stack 1, a hydrogen gas passage 1a for allowing hydrogen gas to pass therethrough, an air passage 1b for allowing air to pass therethrough, and a pure water circulation passage 1c for circulating pure water are formed therein.

  The fuel cell constituting the fuel cell stack 1 has an internal configuration as shown in FIG. 2, for example. This fuel cell is provided between the hydrogen gas passage 1a and the air passage 1b, and between the solid polymer electrolyte membrane 31 provided between the hydrogen gas passage 1a and the air passage 1b, and between the hydrogen gas passage 1a and the pure water circulation passage 1c. The porous plate 32 is sandwiched between two separator plates 33. Hydrogen gas, air, and pure water are introduced into such a fuel cell by adjusting the pressure so as to be within a predetermined pressure difference range.

  The fuel cell is vaporized by the porous plate 32 from the pure water circulation channel 1c when hydrogen gas is supplied to the hydrogen gas channel 1a, air is supplied to the air channel 1b, and pure water is supplied to the pure water circulation channel 1c. The moistened water enters the hydrogen gas flow path 1a, and the humidified hydrogen gas passes through. Thereby, the fuel cell holds the solid polymer electrolyte membrane 31 in a wet state by the hydrogen gas humidified by the pure water flowing through the pure water circulation passage 1c and the air humidified by the humidifier 18 described later. Acts like

  In addition, this fuel battery cell uses a porous plate 32 to condense condensed water generated in the vicinity of the hydrogen gas outlet of the hydrogen gas channel 1a when moisture enters the hydrogen gas channel 1a from the pure water circulation channel 1c. It acts to take in and discharge into the pure water circulation channel 1c. Thereby, the fuel cell prevents water clogging in which the hydrogen gas channel 1a is closed by the condensed water.

  Further, in this fuel cell system, a hydrogen circulation system that circulates hydrogen gas used for the power generation reaction of the fuel cell stack 1, an air supply system that supplies air used for the power generation reaction of the fuel cell stack 1, and the fuel cell stack 1 has a pure water circulation system for circulating pure water used for humidification and cooling. The operation of each of these systems is controlled by inputting a control signal from the controller 2 described later.

  In the hydrogen circulation system, a hydrogen supply pipe L1 connected to a hydrogen gas inlet of the fuel cell stack 1 is provided with, for example, a hydrogen supply device 11 including a hydrogen tank, a hydrogen cutoff valve 12, a hydrogen pressure regulating valve 13, and an ejector 14. Yes. The hydrogen circulation system includes a hydrogen circulation pipe L2 that connects the hydrogen gas outlet of the fuel cell stack 1 and the ejector 14 of the hydrogen supply pipe L1, a hydrogen discharge pipe L3 branched from the hydrogen circulation pipe L2, and the hydrogen discharge pipe. A purge valve 15 provided at L3 is provided.

  In such a hydrogen circulation system, when the fuel cell stack 1 is caused to generate power, the hydrogen shutoff valve 12 is opened and the opening of the hydrogen pressure regulating valve 13 is adjusted to adjust the hydrogen gas pressure to supply hydrogen. Hydrogen gas is sent from the device 11 to the hydrogen gas inlet of the fuel cell stack 1. Thereby, in a hydrogen circulation system, the hydrogen gas pressure in the hydrogen gas flow path 1a is adjusted.

  The fuel cell stack 1 uses a part of the hydrogen for the power generation reaction and discharges a part of the hydrogen not used for the power generation reaction from the hydrogen gas outlet to the hydrogen circulation pipe L2. The hydrogen gas discharged from the hydrogen gas outlet of the fuel cell stack 1 is taken in by the ejector 14 using the kinetic energy of the hydrogen gas supplied from the hydrogen supply device 11, and is again passed through the hydrogen supply pipe L1 as circulating hydrogen. To the hydrogen gas inlet of the fuel cell stack 1. Accordingly, the fuel cell system increases the amount of hydrogen supplied to the hydrogen gas inlet of the fuel cell stack 1 and supplies the hydrogen gas to each fuel cell constituting the fuel cell stack 1 without a shortage.

  In this hydrogen circulation system, the controller 2 opens the purge valve 15 when purging the gas in the hydrogen supply pipe L1 and the hydrogen circulation pipe L2. Thereby, in the hydrogen circulation system, impurities other than hydrogen accumulated in the hydrogen circulation pipe L2 are discharged through the hydrogen discharge pipe L3.

  In the air supply system, an air supply device 16, a heat exchanger 17, and a humidifier 18 are provided in an air supply pipe L 4 connected to the air inlet of the fuel cell stack 1, and the air connected to the air outlet of the fuel cell stack 1. A humidifier 18 and an air pressure adjustment valve 19 are provided in the discharge pipe L5.

  In such an air supply system, when the fuel cell stack 1 is caused to generate electric power, compressed air that has been heated by compressing outside air by the air supply device 16 that is an oxidant gas compression device, sending it to the heat exchanger 17, and compressing it. Is cooled by the heat exchanger 17. Here, the heat exchanger 17 cools the fuel cell stack 1 by, for example, arranging a cooling medium pipe 17a connected to a cooling medium circulation system that circulates the cooling medium to the fuel cell stack 1 (not shown). The medium is shared and the compressed air is cooled and sent to the humidifier 18.

  The humidifier 18 humidifies the compressed air sent from the heat exchanger 17 and supplies it to the fuel cell stack 1. Here, the humidifier 18 includes a membrane made of a material having high moisture permeability such as polyimide, and is included in the exhaust air supplied through the air exhaust pipe L5 connected to the air outlet of the fuel cell stack 1. Moisture is moved to the air supply pipe L4 side. Thereby, the humidifier 18 humidifies the dried compressed air to humidify the solid polymer electrolyte in the fuel cell stack 1.

  Further, in this air supply system, the controller 2 adjusts the opening degree of the air pressure adjustment valve 19 in the air discharge pipe L5 on the exhaust air downstream side of the humidifier 18, and the fuel cell stack 1 is operated in a good state. Thus, the air pressure in the air flow path 1b is adjusted.

  In the pure water circulation system, when the solid polymer electrolyte of the fuel cell stack 1 is porous, a relatively large amount of pure water is supplied to the porous solid polymer electrolyte for humidification, or the fuel cell stack In order to adjust the temperature of 1, pure water is circulated in the pure water circulation passage 1 c of the fuel cell stack 1. The pure water circulation system includes a pure water supply pipe L6 and a pure water circulation pipe L7 that connect the pure water circulation flow path 1c of the fuel cell stack 1 and the pure water tank 20. A pure water tank 20 and a pure water pump 21 are connected to the pure water supply pipe L6. In such a pure water circulation system, the pure water pump 21 is driven by the controller 2 when the fuel cell stack 1 is generating electric power. Thus, in the pure water circulation system, pure water in the pure water tank 20 is taken in by the pure water pump 21, and pure water is supplied to the pure water circulation passage 1c via the pure water supply pipe L6. The pure water discharged from the flow path 1c is returned to the pure water tank 20.

  Furthermore, the fuel cell system includes an air introduction pipe L8 for connecting the air supply pipe L4 and the pure water tank 20, and a ventilation pipe L9 for connecting the outside air and the pure water tank 20. The air introduction pipe L8 is connected to an air introduction inlet provided at a position higher than the pure water surface when the pure water tank 20 is full.

  In addition, the air introduction pipe L8 is partially formed with a throttle portion 22 for adjusting the air pressure loss. The throttle unit 22 is configured by, for example, an orifice mechanism, and is configured to adjust the flow rate of air introduced into the pure water tank 20 from the air supply pipe L4. Note that the throttle unit 22 is not limited to an orifice mechanism, but may be a flow rate adjustment valve or an on-off valve that is opened and closed by an actuator.

  In the fuel cell system having such systems, when the fuel cell stack 1 is caused to generate power, the compressed air sent from the air supply pipe L4 to the fuel cell stack 1 is subjected to pressure loss by the throttle portion 22, and the air introduction pipe. It introduces into the pure water tank 20 through L8. As a result, the gas in the pure water tank 20 becomes a gas mixed with air and is exhausted from the pure water tank 20 through the vent pipe L9 which is a gas discharge pipe.

  Here, since the hydrogen gas flow path 1 a and the pure water circulation flow path 1 c are separated through the porous plate 32 inside the fuel cell stack 1, the hydrogen is formed by the holes formed in the porous plate 32. Gas and pure water are in direct contact with each other. For this reason, in the fuel cell stack 1, hydrogen flowing through the hydrogen gas passage 1a is dissolved in pure water flowing through the pure water circulation passage 1c, or the pure water circulation is performed more than the pressure value in the hydrogen gas passage 1a. When the pressure value in the channel 1c is small, a phenomenon occurs in which hydrogen is taken into pure water due to a pressure difference. When such a phenomenon occurs, hydrogen mixed in the pure water flows through the pure water circulation pipe L7, flows into the pure water tank 20, and is released into the gas of the pure water tank 20. As a result, hydrogen-containing gas accumulates in the pure water tank 20.

  On the other hand, in the fuel cell system, compressed air is supplied to the fuel cell stack 1 to generate electric power, and the compressed air is introduced into the pure water tank 20 so that hydrogen accumulated in the pure water tank 20 is compressed air. Dilute with and discharge. At this time, the controller 2 takes in the air flow rate necessary for diluting the hydrogen in the pure water tank 20 in addition to the air flow rate necessary for generating the power generation amount required for the fuel cell stack 1. The air supply device 16 is controlled. Specifically, the controller 2 is introduced into the pure water tank 20 based on, for example, the hole diameter of the porous plate 32, the capacity of the pure water tank 20, the flow rate of hydrogen entering the pure water tank 20 per unit time, and the like. The air supply device 16 controls the air flow rate to be taken in. The flow rate of air introduced into the pure water tank 20 is within the range of operating conditions of the fuel cell system, and the amount of hydrogen entering the pure water tank 20 from the fuel cell stack 1 is obtained in advance by experiments or the like. The hydrogen concentration in the water tank 20 is adjusted by the throttle unit 22 that can sufficiently dilute the hydrogen concentration to a concentration below the flammable range.

[Effect of the first embodiment]
As described above in detail, according to the fuel cell system according to the first embodiment, since compressed air is introduced into the pure water tank 20, hydrogen is mixed into the pure water and hydrogen is contained in the pure water tank 20. Even in the case of accumulation, hydrogen in the pure water tank 20 can be diluted with compressed air and discharged to ventilate the pure water tank 20.

  Moreover, according to this fuel cell system, since the air introduction pipe L8 branched from the air supply pipe L4 on the upstream side of the fuel cell stack 1 is provided, the air pressure in the air supply pipe L4 is at least in the air flow path 1b. Therefore, even when the fuel cell stack 1 generates power at a low pressure even when the amount of power generation required for the fuel cell stack 1 is small, Compressed air can be introduced.

  Furthermore, according to this fuel cell system, the air supply pipe L8 branched from the air supply pipe L4 on the downstream side of the heat exchanger 17 is provided, and the compressed air that has passed through the heat exchanger 17 is introduced into the pure water tank 20. Therefore, even when the amount of power generation required for the fuel cell stack 1 is high and it is necessary to operate in a state where the fluid pressure in the fuel cell stack 1 is high, the compressed air cooled by the heat exchanger 17 is used. The air can be introduced into the pure water tank 20, and the air introduction pipe L8 can be made of a resin material having a low heat-resistant temperature or made of rubber. Therefore, according to this fuel cell system, even in the configuration in which the air introduction pipe L8 and the ventilation pipe L9 are added, it is possible to improve the mountability of the vehicle or the like in which the mounting space is limited.

  Furthermore, according to this fuel cell system, the compressed air having a lower temperature than the compressed air upstream of the heat exchanger 17 is introduced into the pure water tank 20, so that it is given to the pure water in the pure water tank 20. The amount of heat can be reduced, vaporization of pure water can be suppressed, and the water balance efficiency as a system can be prevented from decreasing.

  Furthermore, according to this fuel cell system, the air introduction pipe L8 branched from the air supply pipe L4 between the heat exchanger 17 and the humidifier 18 is provided, and the compressed air is branched from the upstream side of the humidifier 18 to supply compressed air. Since it has been introduced into the pure water tank 20, in addition to the effect of providing the air introduction pipe L8 branched from the downstream side of the heat exchanger 17, the compressed air in the air introduction pipe L8 should be in a dry state. Thus, moisture does not condense in the air introduction pipe L8. Therefore, according to this fuel cell system, the compressed air that has been humidified is supplied to the air introduction pipe L8 to cause water clogging in the throttle portion 22, the air flow rate to the pure water tank 20 is reduced, and hydrogen is removed. Air can be stably introduced into the pure water tank 20 without a shortage of air flow for dilution.

  Furthermore, according to this fuel cell system, when the condensed water remains in the air introduction pipe L8 and is exposed to the atmospheric temperature below freezing point, the air introduction pipe L8 is not deteriorated by freezing.

  Furthermore, according to this fuel cell system, all of the compressed air humidified by the humidifier 18 is supplied to the fuel cell stack 1 and the moisture contained in the compressed air discharged from the fuel cell stack 1 is recovered by the humidifier 18. Since it can be reused for humidification, the water balance performance of the entire system can be improved without discharging the recovered water to the pure water tank 20.

  Furthermore, according to this fuel cell system, since the throttle portion 22 comprising the orifice mechanism is provided in the air introduction pipe L8, the flow rate of air introduced from the air supply pipe L4 to the pure water tank 20 can be adjusted, and the In addition, the hydrogen concentration in the pure water tank 20 can be reduced and discharged.

[Second Embodiment]
Next, a fuel cell system according to a second embodiment will be described. In addition, about the part similar to the above-mentioned 1st Embodiment, the detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 3, the fuel cell system according to the second embodiment branches from an air supply pipe L4 connecting the air supply device 16 and the heat exchanger 17 instead of the air introduction pipe L8. The fuel cell system according to the first embodiment is different from the fuel cell system according to the first embodiment in that an air introduction pipe L10 connected to the water tank 20 is provided.

  That is, this fuel cell system is configured to branch compressed air from the upstream side of the heat exchanger 17 and introduce it into the pure water tank 20. Further, in this fuel cell system, the throttle portion 22 that supplies the air flow rate that can be diluted from the air supply device 16 to the pure water tank 20 until the concentration of hydrogen accumulated in the pure water tank 20 becomes equal to or less than the flammable concentration is the air introduction pipe. L10 is provided.

  According to the fuel cell system configured as described above, the compressed air is supplied to the pure water tank 20 from the upstream side of the heat exchanger 17, so that the high-temperature compressed air discharged from the air supply device 16 is supplied to the pure water tank 20. Can be introduced. As a result, according to the fuel cell system, when the fuel cell stack 1 is activated in a sub-freezing temperature environment, the controller 2 controls the air pressure regulating valve 19 to increase the operating pressure of the fuel cell stack 1, The temperature of the compressed air discharged from the air supply device 16 is increased, and the frozen water adhering to the air introduction pipe L10 and the frozen water in the pure water tank 20 are thawed in a short time in the previous system stop. be able to.

[Third Embodiment]
Next, a fuel cell system according to a third embodiment will be described. In addition, about the part similar to the above-mentioned 1st Embodiment, the detailed description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  As shown in FIG. 4, the fuel cell system according to the third embodiment connects a pure water tank 20 and an air supply pipe L4 between the humidifier 18 and the fuel cell stack 1 instead of the ventilation pipe L9. It differs from the fuel cell system which concerns on embodiment mentioned above by the point provided with the gas discharge piping L11 to perform. That is, in this fuel cell system, the gas composed of compressed air and hydrogen mixed in the pure water tank 20 is introduced into the air supply pipe L4 on the downstream side of the humidifier 18 without being discharged to the outside air.

  In such a fuel cell system, by introducing compressed air into the pure water tank 20 via the air introduction pipe L10, hydrogen mixed with pure water and accumulated in the pure water tank 20 is diluted, and the dilution is performed. The introduced gas is introduced into the air supply pipe L4 through the gas discharge pipe L11. Thus, in the fuel cell system, the gas obtained by mixing hydrogen and compressed air in the pure water tank 20 and the compressed air flowing from the air supply pipe L4 to the fuel cell stack 1 are mixed and introduced into the fuel cell stack 1. To do.

  Here, since the compressed air is not discharged from the pure water tank 20 to the outside, the controller 2 performs control so that an air flow rate corresponding to the power generation amount required for the fuel cell stack 1 is discharged from the air supply device 16.

  According to such a fuel cell system, since the compressed air introduced and discharged into the pure water tank 20 is introduced into the fuel cell stack 1, the compressed air is branched from the air supply pipe L4 into the pure water tank 20. Even when the fuel cell stack 1 is introduced, the hydrogen in the pure water tank 20 can be diluted only by discharging compressed air at a flow rate necessary for power generation of the fuel cell stack 1 from the air supply device 16. Therefore, according to this fuel cell system, the electric power used for the air supply device 16 can be reduced as compared with the fuel cell system according to the above-described embodiment. Therefore, according to this fuel cell system, it is possible to dilute the hydrogen in the pure water tank 20 without reducing the power use efficiency.

  Further, according to this fuel cell system, the compressed air is introduced into the pure water tank 20 through the air introduction pipe L10 branched from the air supply pipe L4 upstream of the heat exchanger 17, so that the temperature rises due to compression. By introducing the compressed air into the pure water tank 20, the pure water is vaporized by the amount of heat of the compressed air, and the compressed air discharged from the pure water tank 20 is humidified by the moisture generated by the vaporization of the pure water. The humidity can be increased. Therefore, according to this fuel cell system, even when the gas discharged from the pure water tank 20 is introduced downstream of the humidifier 18, the humidity of the compressed air supplied to the fuel cell stack 1 is not reduced. The fuel cell stack 1 can be stably generated.

  The above-described embodiment is an example of the present invention. For this reason, the present invention is not limited to the above-described embodiment, and various modifications can be made depending on the design and the like as long as the technical idea according to the present invention is not deviated from this embodiment. Of course, it is possible to change.

It is a block diagram which shows the structure of the fuel cell system which concerns on 1st Embodiment to which this invention is applied. It is sectional drawing which shows the structure of the fuel cell of the fuel cell stack which comprises the fuel cell system which concerns on 1st Embodiment to which this invention is applied. It is a block diagram which shows the structure of the fuel cell system which concerns on 2nd Embodiment to which this invention is applied. It is a block diagram which shows the structure of the fuel cell system which concerns on 3rd Embodiment to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell stack 2 Controller 11 Hydrogen supply apparatus 12 Hydrogen shut-off valve 13 Hydrogen pressure regulating valve 14 Ejector 15 Purge valve 16 Air supply apparatus 17 Heat exchanger 18 Humidifier 19 Air pressure adjustment valve 20 Pure water tank 21 Pure water pump 22 Restriction part L1 Hydrogen supply line L2 Hydrogen circulation line L3 Hydrogen discharge line L4 Air supply line L5 Air discharge line L6 Pure water supply line L7 Pure water circulation line L8, L10 Air introduction line L9 Vent line L11 Gas exhaust line

Claims (8)

A fuel cell system that generates power from a fuel cell that includes a fuel electrode to which fuel gas is supplied, an oxidant electrode to which oxidant gas is supplied, and a water passage through which water passes,
The fuel gas is supplied to the fuel electrode of the fuel cell, and the oxidant gas is supplied to the oxidant electrode of the fuel cell via an oxidant gas supply pipe connecting the oxidant gas compression device and the oxidant electrode of the fuel cell. And introducing the oxidant gas into a water tank for storing water to be supplied to the water flow path of the fuel cell via an oxidant gas introduction pipe branched from a pipe through which the oxidant gas flows. A fuel cell system for discharging gas in a water tank to the outside of the water tank through a gas discharge pipe. A fuel cell that includes a fuel electrode to which fuel gas is supplied, an oxidant electrode to which oxidant gas is supplied, and a water flow path through which water passes, and that generates power using the fuel gas and oxidant gas;
Fuel gas supply means for supplying fuel gas to the fuel electrode of the fuel cell;
An oxidant gas supply pipe for connecting an oxidant gas compression device and an oxidant electrode of the fuel cell, and an oxidant gas supply means for supplying an oxidant gas to the oxidant electrode of the fuel cell;
A water tank for storing water to be supplied to the water flow path of the fuel cell; water circulation means for circulating the water stored in the water tank to the water flow path of the fuel cell;
Branching from a pipe through which the oxidant gas flows, and an oxidant gas introduction pipe for introducing the oxidant gas into the water tank;
A fuel cell system comprising: a gas discharge pipe for discharging the gas in the water tank to the outside of the water tank.   3. The fuel cell system according to claim 1, wherein the oxidant gas introduction pipe is branched from the oxidant gas supply pipe upstream of the oxidant electrode of the fuel cell. A heat exchanger that is provided in the oxidant gas supply pipe and adjusts the temperature of the oxidant gas compressed by the oxidant gas compression device;
The oxidant gas introduction pipe is branched from the oxidant gas supply pipe on the downstream side of the heat exchanger and upstream of the oxidant electrode of the fuel cell. 4. The fuel cell system according to 3. A heat exchanger that is provided in the oxidant gas supply pipe and adjusts the temperature of the oxidant gas compressed by the oxidant gas compression device;
The fuel cell system according to claim 3, wherein the oxidant gas introduction pipe is branched from the oxidant gas supply pipe on the upstream side of the heat exchanger. A heat exchanger that is provided in the oxidant gas supply pipe and adjusts the temperature of the oxidant gas compressed by the oxidant gas compression device;
A humidifier provided in an oxidant gas supply pipe on the downstream side of the heat exchanger, and humidifies the oxidant gas compressed by the oxidant gas compressor;
The fuel cell system according to claim 3, wherein the oxidant gas introduction pipe is branched from the oxidant gas supply pipe between the heat exchanger and the humidifier.   The fuel cell system according to any one of claims 1 to 6, wherein the gas discharge pipe and the oxidant gas supply pipe are connected. 8. The oxidant gas introduction pipe is provided with an orifice mechanism for giving a pressure loss to the oxidant gas introduced from the oxidant gas supply pipe into the water tank. The fuel cell system described in 1.

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