JP2004185969A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of efficiently keeping and supplying suitable purge gas. <P>SOLUTION: The fuel cell system is equipped with a fuel cell 7, an air system having a compressor 4 and a humidifier 5, and a fuel system having a hydrogen supplying valve 8 selecting supply of hydrogen gas, and a purge valve 9 selecting exhaustion of exhaust fuel gas. Further, as a purge gas system, including a passage branching off from a branch part 11 between the compressor 4 and the humidifier 5 and connected to a downstream of the hydrogen supplying valve 8, the fuel cell system is equipped with an air storing pressure accumulation tank 1, a check valve 2 supplying air to the pressure accumulation tank 1 when pressure P<SB>1</SB>near the branch part 11 is higher than pressure P<SB>2</SB>in the pressure accumulation tank 1, and a purge valve 9 selecting fuel system purge by air in the pressure accumulation tank 1. When the system is stopped, the constitution of a purge gas system to purge the inside of the fuel cell can be obtained. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a fuel cell system. Particularly, the present invention relates to a configuration of a purge gas system for purging the inside of a fuel cell when the system is stopped.
[0002]
[Prior art]
In a conventional fuel cell system, an air inlet and a reactive gas outlet are provided on a plurality of surfaces of a case in which a fuel cell main body is housed. Therefore, when the power supply is not used, there is a possibility that outside air may enter the case from the intake and exhaust ports. As a result, there has been a problem that the electrolyte of the fuel cell absorbs moisture in the outside air, the electrolyte concentration is reduced, and the battery characteristics are deteriorated.
[0003]
Therefore, the following fuel cell system has been proposed in order to securely seal the fuel cell main body when the power supply is not used and to prevent a pressure drop due to the consumption of residual gas in the fuel cell after the operation is stopped.
[0004]
The fuel cell includes a shut-off film provided in an air supply path and a fuel gas discharge path of the fuel cell body, and a purge flow path connecting the fuel gas inlet and the air outlet. Thereby, after the fuel electrode is purged with the air electrode exhaust gas when the operation is stopped, the fuel electrode is sealed with a shut-off film, so that a pressure drop due to the consumption of residual gas in the fuel cell body and the invasion of outside air, moisture, foreign matter, and the like can be prevented ( For example, see Patent Document 1.)
[0005]
[Patent Document 1]
JP-A-9-213358
[Problems to be solved by the invention]
However, in the conventional fuel cell system, a tank for storing cathode air exhaust gas for accumulating pressure is provided on the supply air flow path, and the cathode exhaust gas is discharged from the outlet after the inside of the tank reaches a predetermined pressure or more. Therefore, there is a problem that the pressure loss of the air system is large. In addition, since the cathode exhaust gas tank is disposed downstream of the fuel cell, there is a problem that water vapor generated by the reaction of the fuel cell is condensed in the air.
[0007]
In view of the above problems, an object of the present invention is to provide a fuel cell system that can efficiently secure and supply an appropriate purge gas.
[0008]
[Means for solving the problem]
The present invention includes a fuel cell main body that generates power using a fuel gas and an oxidant, and an oxidant system including a compression unit and a humidifying unit for supplying a humidified oxidant to the fuel cell. A fuel gas supply selection valve for selecting whether or not to supply fuel gas to the fuel cell; and a purge selection valve for selecting whether to discharge fuel exhaust gas from the fuel cell. And a system. Further, as a purge gas system including a flow path branched from between the compression means and the humidification means and connected downstream of the fuel gas supply selection valve, a tank storing at least a part of an oxidizing agent, the compression means, An oxidizing agent introduction selecting valve for supplying an oxidizing agent to the tank when the pressure near the branch between the humidifying means becomes higher than the pressure in the tank; and at least one of the fuel gas system by the oxidizing agent in the tank. A purge gas supply selection valve for selecting whether or not to purge the section.
[0009]
Alternatively, the fuel cell includes a fuel cell main body that generates power using a fuel gas and an oxidant, and an oxidant system including a compression unit and a humidifying unit for supplying the humidified oxidant to the fuel cell. A fuel gas supply selecting means for selecting whether or not to supply fuel gas to the fuel cell; and a purge selecting means for selecting whether to discharge fuel exhaust gas from the fuel cell. With system. A tank for storing at least a part of the oxidant; an oxidant introduction selecting means for selecting whether or not to supply the oxidant to the tank; and an oxidant in the tank for at least a part of the fuel gas system. Purge gas supply selection means for selecting whether or not to supply the fuel gas to the fuel gas supply means, and a purge gas system branched from between the compression means and the humidification means and connected downstream of the fuel gas supply selection means. During the operation of the system, when the pressure near the branching point branching from the compression means and the humidifying means to the purge gas system becomes higher than the pressure in the tank, an oxidizing agent is introduced into the tank, and when the system is stopped, At least a portion of the fuel gas system is purged using an oxidant stored in the tank.
[0010]
[Action and effect]
An oxidant introduction selection valve for supplying an oxidant to the tank when the pressure near the branch becomes higher than the pressure in the tank. Thereby, the oxidant can be stored in the tank without increasing the pressure loss of the oxidant supplied to the fuel cell during the operation of the system. Further, the purge gas system is configured to branch off from between the compression means and the humidification means and to be connected downstream of the fuel gas supply selection means. Since the oxidizing agent before being humidified is stored in this way, it is possible to prevent water from accumulating in the tank. This makes it possible to efficiently secure and supply an appropriate purge gas.
[0011]
Alternatively, during system operation, when the pressure in the vicinity of the branch point from the compression means and humidification means to the purge gas system becomes higher than the pressure in the tank, an oxidizing agent is introduced into the tank and stored in the tank when the system is stopped. At least a part of the fuel gas system is purged using the oxidizing agent. As described above, the humidified oxidant is compressed and stored without using power, and is used as a purge gas when the system is stopped, so that the fuel gas system is sufficiently purged and water adheres to the fuel gas system. Can be prevented.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows the configuration of the fuel cell system used in the present embodiment. Here, a polymer electrolyte fuel cell system that requires humidification of the electrolyte membrane is used, and air is used as the oxidant gas, and hydrogen gas is used as the fuel gas.
[0013]
First, an air system (oxidant system) for supplying and discharging air to and from the air electrode of the fuel cell 7 will be described.
[0014]
A compressor 4 for compressing and introducing air, a cooler 6 for adjusting the temperature of air, and a humidifier 5 for humidifying air are provided. The humidified and high-pressure air is supplied to the air electrode of the fuel cell 7 via the compressor 4, the cooler 6, and the humidifier 5. At the air electrode, a reaction (2H ⁺ + 2e ⁻ + 1 / 2O ₂ → H ₂ O) using oxygen in the air and proton ions transferred from the fuel electrode via the electrolyte membrane occurs. Thereafter, the air not used for the reaction is discharged from the fuel cell 7 as air exhaust gas, and discharged to the outside of the system via the pressure regulating valve 10. Here, the pressure regulating valve 10 is a valve for adjusting the pressure of the air electrode of the fuel cell 7.
[0015]
Next, a fuel system (fuel gas system) for supplying and discharging hydrogen gas to and from the fuel electrode of the fuel cell 7 will be described.
[0016]
A hydrogen supply valve 8 for selecting the supply of hydrogen gas is provided. On the downstream side of the hydrogen supply valve 8, a recirculation introduction unit 13 is provided, which is connected to a circulation path 14 for recirculating fuel exhaust gas discharged from the fuel electrode, as described later. Hydrogen gas introduced from a hydrogen supply means such as a hydrogen tank (not shown) is supplied to the fuel electrode of the fuel cell 7 via the hydrogen supply valve 8. At this time, fuel exhaust gas is also supplied to the fuel electrode via the recirculation introduction unit 13. Here, the fuel gas is a hydrogen gas introduced from a hydrogen supply means such as a hydrogen tank, but may be a reformed fuel gas generated by a fuel reforming system.
[0017]
The hydrogen supplied to the fuel cell 7 causes a reaction (H ₂ → 2H ⁺ + 2e ⁻ ), converts the hydrogen into proton ions, and moves the hydrogen to the air electrode via the electrolyte membrane to generate an electromotive force. Although hydrogen is consumed by this reaction, not all oxygen is consumed, and some hydrogen is discharged from the fuel cell 7 without reacting. The discharged fuel exhaust gas is introduced again into the fuel cell 7 from the recirculation introduction unit 13 provided on the supply side of the fuel electrode through the circulation path 14, and is used for power generation. A discharge path 15 communicating with the outside of the hydrogen gas circulation path 14 is provided, and the purge valve 9 is disposed in the discharge path 15. The opening and closing of the purge valve 9 makes it possible to discharge the fuel exhaust gas in the circulation path 14. For example, when the fuel electrode in the fuel cell 7 is clogged with water, or when impurities in the hydrogen gas increase and the output of the fuel cell 7 decreases, the purge hydrogen valve 9 is opened and the flow rate of the supplied hydrogen gas is reduced. Purge the gas in the fuel electrode by increasing. Further, when the fuel cell system is stopped, the reaction during the system stop is suppressed by purging the gas in the fuel electrode using the purge gas.
[0018]
Next, a purge gas system for storing and supplying a purge gas for purging a gas at the fuel electrode will be described. Here, it is constituted by a flow path connecting the above-described supply side of the air electrode and the supply side of the fuel electrode.
[0019]
A path connecting a branch portion 11 provided between the compressor 4 and the humidifier 5 on the supply side of the air system and an introduction portion 12 provided on the downstream side of the hydrogen supply valve 8 on the supply side of the fuel system is connected to a purge gas system. I do. Here, the branch portion 11 is provided between the cooler 6 and the humidifier 5. Further, the introduction section 12 is provided immediately downstream of the hydrogen supply valve 8. For example, the junction 12 is provided between the hydrogen supply valve 8 and the recirculation introduction unit 13.
[0020]
The purge gas system includes a check valve 2, a pressure storage tank 1, and a flow path opening / closing valve 3 from the branch portion 11 side. Here, the pressure of the air system, for example the pressure of the branch portion 11 and P _1, the pressure in the accumulator tank 1 and P _2. The check valve 2 is a valve that opens when the accumulator tank pressure P ₂ is increased by a predetermined pressure P ₀ from the bifurcation pressure P _1. Thereby, by increasing the pressure on the supply side of the air system, the air is branched from the branch portion 11 and stored in the accumulator tank 2. Here, since air is supplied into the accumulator tank 1 by the pressure difference between the pressure (P ₂ ) of the air compressed by the compressor 4 and the pressure P ₁ in the accumulator tank 1, the pressure in the accumulator tank 1 is reduced. High pressure can be set. Further, the passage opening / closing valve 3 is always closed during system operation, and separates the air system and the fuel system.
[0021]
When the system is stopped, the hydrogen supply valve 8 is closed, and then the flow path on-off valve 3 and the purge valve 9 are opened. Thereby, most of the hydrogen gas in the fuel system downstream of the hydrogen supply valve 8 can be quickly discharged by the air pressure and the volume of the accumulator tank 1. This can prevent a reaction (power generation) due to residual hydrogen while the system is stopped.
[0022]
Here, an electromagnetic valve is used in which the flow path on-off valve 3 and the purge valve 9 are opened when the power is not supplied, and the hydrogen supply valve 8 is closed when the power is not supplied. Further, a controller 20 for controlling the fuel cell system is provided. The controller 20 may be configured by a controller unit that controls the entire system, but here, a controller that secures and supplies the purge gas when the system is stopped.
[0023]
Next, the operation of the fuel cell system in a normal state will be described with reference to the flowchart of FIG. This flow is an operation in which a command to start power generation in the fuel cell 7 is detected, and an air system such as the compressor 4 is started and then started.
[0024]
First, the operation at the start of operation will be described. In step S1, the flow path on-off valve 3 is closed to separate the fuel system from the air system. In step S2, the hydrogen supply valve 8 is opened to introduce hydrogen gas into the fuel system. Thus, oxygen and hydrogen are supplied to the fuel cell 7, and the power generation operation starts.
[0025]
In this embodiment, since the solenoid valves are used as the flow path on-off valve 3, the hydrogen supply valve 8, and the purge valve 9, the flow path on-off valve 3, the purge valve 9 are energized, and then the hydrogen supply valve 8 is energized. Thereby, steps S1 and S2 can be realized.
[0026]
Next, an operation for storing the purge gas during the power generation operation will be described.
[0027]
In step S3, it is compared with the difference between the branch portion pressure _{P 1} and the accumulator tank pressure _{P 2 (P} 1 -P _2), and a pressure _{P 0} where opening the check valve 2. Here, the predetermined pressure P ₀ is a sum of a pressure set by the configuration of the check valve 2 and a pressure corresponding to a loss from the branch portion 11 to the pressure accumulating tank 1. In step S3, if the less the pressure difference _P 1 -P ₂ is the predetermined pressure _{P 0,} in step S6, the check valve 2 is closed as described later. At this time, the accumulation of air in the pressure accumulation tank 1 is not performed.
[0028]
On the other hand, if the differential pressure P ₁ -P ₂ is larger than the predetermined pressure P ₀ , the process proceeds to step S4. In step S4, the check valve 2 is opened. Thereby, air is supplied to the pressure accumulating tank 1 by an amount corresponding to the pressure difference between the branch portion 11 and the pressure accumulating tank 1. In step S5, again compared with the difference between the branch portion pressure _{P 1} and the accumulator tank pressure _{P 2 (P} 1 -P _2), and a pressure _{P 0} where the check valve 2 is opened. This state is maintained until the differential pressure P ₁ -P ₂ becomes equal to or lower than the predetermined pressure P _0, and when the differential pressure P ₁ -P ₂ becomes equal to or lower than P ₀ , the process proceeds to step S6, and the check valve 2 is closed. Thereby, pressurized air is accumulated in the pressure accumulation tank 1. Here, the internal pressure P ₂ of the accumulator tank 2 with increasing P ₁ pressure during operation also increases.
[0029]
In step S7, it is determined whether a command to stop the fuel cell system has been detected. If the stop command has not been detected, the flow returns to step S3, and the storage of the air used as the purge gas in the pressure accumulating tank 1 is continued. On the other hand, if a stop command is detected in step S7, the process proceeds to step S8.
[0030]
In this embodiment, since the check valve 2 is used, the opening and closing are performed automatically, so that the operations in steps S3 to S6 do not need to be controlled by the controller 20. However, in order to secure the purge gas at an early stage, it is desirable to store the air in the accumulator tank 1 by increasing the load on the compressor 4 at the beginning of startup. For example, the air in the accumulator tank 1 is obtained beforehand by experiments or the like the pressure P ₁ of the branch portion 11 such that a predetermined pressure. At the same time as the start, the compressor 4 introduces air at a predetermined pressure, and then returns the load of the compressor 4 to the load during normal operation when the check valve 2 is closed. As a result, the purge gas can be secured at an early stage, in this case, at an early stage at the time of startup.
[0031]
Further, instead of the check valve 2, a valve or the like that only shuts off the flow path can be used. In this case, the branch section 11 and the pressure accumulation tank 1 need to be provided with pressure sensors for detecting the respective pressures, and the controller 20 needs to control the steps S3 to S6.
[0032]
Next, control at the time of operation stop will be described. In step S8, the hydrogen supply valve 8 is closed. As a result, the supply of hydrogen gas to the fuel cell 7 is stopped, and the power generation is stopped. In step S9, the purge valve 9 is opened. Subsequently, in step S10, the flow path on-off valve 3 is opened. Thereby, the air stored in the accumulator tank 1 is supplied to the fuel system from the downstream side of the hydrogen supply valve 8. As a result, the fuel gas containing hydrogen in the fuel electrode and the pipe for supplying or discharging hydrogen is purged. Here, since the purge 9 is opened to open air, the hydrogen remaining in the fuel electrode and the pipe for supplying or discharging hydrogen is reduced to almost zero from the difference between the pressure in the accumulator tank 1 and the external pressure. can do.
[0033]
The operations in steps S8 to S10 during operation stop can be realized by sequentially turning off the hydrogen supply valve 8, the purge valve 9, and the flow path on-off valve 3.
[0034]
Next, the control at the time of the forced stop will be described with reference to the flowchart of FIG.
[0035]
If a forced stop signal is detected during normal operation, the process proceeds to step S11. In step S11, the flow path on-off valve 3 and the purge valve 9 are opened, and the hydrogen supply valve 8 is closed. Here, it can be realized by turning off the power supply. Therefore, as in the case of the normal stop, the hydrogen in the fuel system can be quickly discharged.
[0036]
Next, effects of the present embodiment will be described.
[0037]
The fuel cell system has a fuel cell body that generates power from air and hydrogen, and an air system including a compressor 4 and a humidifier 5 for supplying humidified air to the fuel cell 7. Further, a fuel system including a hydrogen supply valve 8 for selecting whether hydrogen gas is supplied to the fuel cell 7 and a purge valve 9 for selecting whether to discharge fuel exhaust gas from the fuel cell 7 is provided. Prepare. Further, as a purge gas system including a flow path branched from between the compressor 4 and the humidifier 5 and connected downstream of the hydrogen supply valve 8, the accumulator tank 1 for storing at least a part of air, the compressor 4 and the humidifier A check valve 2 for supplying air to the pressure accumulator tank 1 when the pressure in the vicinity of the branch 11 between the pressure vessels 5 is higher than the pressure in the pressure accumulator tank 1, and purging at least a part of the fuel system by the air in the pressure accumulator tank 1 And a purge valve 9 for selecting whether or not to perform.
[0038]
As described above, since the pressure accumulating tank 1 is branched from the downstream of the pneumatic compressor 4 and accumulates the pressure via the check valve 2, it is possible to accumulate the pressure in the pressure accumulating tank 1 without increasing the pressure loss during system operation. In addition, since the pressure is stored only by the difference between the pressure downstream of the compressor 4 and the pressure in the pressure storage tank 1, the pressure can be stored without using external power. Further, since the branch is provided before the humidifier 5, it is possible to prevent water from accumulating in the pressure accumulating tank 1.
[0039]
Further, the check valve 2 is used as the oxidizing agent introduction selecting means. Accordingly, when the pressure difference (P ₁ −P ₂ ) between the pressure P ₁ near the branch portion 11 between the compressor 4 and the humidifier 5 and the pressure P ₂ in the pressure storage tank is larger than the predetermined value P _0, 1 is supplied with air. Thus, the air as the purge gas can be stored at a high pressure without any particular control, and thus the system can be simplified.
[0040]
When the system is stopped, the supply of hydrogen gas is stopped by the hydrogen supply valve 8, and then the fuel exhaust gas is discharged by the purge valve 9. Here, by opening the flow path opening / closing valve 3 and the purge valve 9, hydrogen in the fuel system can be quickly discharged, so that power generation due to residual hydrogen can be prevented.
[0041]
In addition, the flow path on-off valve 3 and the purge valve 9 are closed when energized, opened when not energized, and the hydrogen supply valve 8 is opened when energized and closed when not energized. As a result, hydrogen in the fuel system can be quickly discharged when power is not supplied, so that residual hydrogen and power generation due to the residual hydrogen can be prevented when the system is forcibly stopped or the like, which is safe.
[0042]
Further, at an early stage of system startup, the load of the compressor 4 is increased to store air at a predetermined pressure in the accumulator tank 1. Accordingly, the pressure accumulation is completed in the early stage of the system startup, so that the influence of the flow rate fluctuation generated at the time of the pressure accumulation can be suppressed by the flow fluctuation at the time of startup, and the fluctuation during the stable operation can be prevented. Further, since the purge gas can be secured at the initial stage at the time of startup, the fuel system can be purged regardless of the operation time of the fuel cell 7.
[0043]
The fuel cell system has a fuel cell body that generates power from air and hydrogen, and an air system including a compressor 4 and a humidifier 5 for supplying humidified air to the fuel cell 7. The fuel system further includes a hydrogen supply valve 8 for selecting whether to supply hydrogen gas to the fuel cell 7 and a purge valve 9 for selecting whether to discharge fuel exhaust gas. Further, a pressure accumulating tank 1 for storing at least a part of air, a check valve 2 for selecting whether or not to supply an oxidizing agent to the pressure accumulating tank 1, and an air in the pressure accumulating tank 1 for at least a part of the hydrogen. A purge gas system branched from between the compressor 4 and the humidifier 5 and connected downstream of the hydrogen supply valve 8 with a flow path opening / closing valve 3 for selecting whether or not to supply the gas. During system operation, air is introduced into the pressure accumulator tank 1 when the pressure P ₁ near the branch 11 that branches from between the compressor 4 and the humidifier 5 to the purge gas system becomes higher than the pressure P ₂ in the pressure accumulator tank 1. I do. Here, introducing air into the accumulator tank 1 When the pressure difference between P ₁ and P ₂ is greater than the predetermined pressure P _0. When the system is stopped, at least a part of the fuel system is purged using the air stored in the pressure accumulation tank 1.
[0044]
As described above, since the pressure accumulating tank 1 is branched from the downstream of the pneumatic compressor 4 and accumulates the pressure via the check valve 2, it is possible to accumulate the pressure in the pressure accumulating tank 1 without increasing the pressure loss during system operation. In addition, since the pressure is stored only by the difference between the pressure downstream of the compressor 4 and the pressure in the pressure storage tank 1, the pressure can be stored without using external power. Further, since the branch is provided before the humidifier 5, it is possible to prevent water from accumulating in the pressure accumulating tank 1. Furthermore, by supplying the air pressurized and stored in the accumulator tank 1 to the fuel system when the system is stopped, the hydrogen gas in the fuel system can be sufficiently purged. At this time, since air before humidification is used as the purge gas, it is possible to avoid adhesion of water to the fuel system, for example, the fuel electrode.
[0045]
It is needless to say that the present invention is not limited to the above-described embodiment, and various changes can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a fuel cell system used in the present embodiment.
FIG. 2 is a flowchart for securing / supplying a purge gas at a normal time in the embodiment.
FIG. 3 is a flowchart of purge gas supply at the time of forced termination in the present embodiment.
[Explanation of symbols]
1 Accumulator tank (tank)
2 Check valve (oxidizing agent introduction selecting valve, oxidizing agent introduction selecting means)
3 Flow path open / close valve (oxidant supply selection valve, oxidant supply selection means)
4 Compressor (compression means)
5 Humidifier (humidifying means)
7 fuel cell 8 hydrogen supply valve (fuel gas supply selection valve, fuel gas supply selection means)
9 Purge valve (purge selection valve, purge selection means)
11 Branch

Claims (6)

A fuel cell body that generates power using a fuel gas and an oxidant,
An oxidizing system including a compressing unit and a humidifying unit for supplying a humidified oxidant to the fuel cell;
A fuel gas system comprising: a fuel gas supply selection valve for selecting whether to supply fuel gas to the fuel cell; and a purge selection valve for selecting whether to discharge fuel exhaust gas from the fuel cell. ,
Further, as a purge gas system including a flow path branched from between the compression means and the humidification means and connected downstream of the fuel gas supply selection valve,
A tank for storing at least a portion of the oxidizing agent,
An oxidant introduction selection valve for supplying an oxidant to the tank when the pressure near the branch between the compression means and the humidifying means is higher than the pressure in the tank;
A fuel cell system, comprising: a purge gas supply selection valve for selecting whether to purge at least a part of the fuel gas system with an oxidant in the tank. A check valve is used as the oxidizing agent introduction selecting means. The fuel cell system according to claim 1, which supplies the fuel cell system. 2. The fuel cell system according to claim 1, wherein when the system is stopped, after the supply of the fuel gas is stopped by the fuel gas supply selection valve, discharge of the fuel exhaust gas is selected by the purge selection valve. 2. The fuel cell system according to claim 1, wherein the purge gas supply selection valve and the purge selection valve are closed when energized, open when not energized, and open when energized and closed when not energized. 3. 2. The fuel cell system according to claim 1, wherein an oxidant at a predetermined pressure is stored in the tank by increasing a load of the compression means at an early stage of system startup. A fuel cell body that generates power using a fuel gas and an oxidant, an oxidant system including a compression unit and a humidifying unit for supplying a humidified oxidant to the fuel cell,
A fuel gas system comprising: a fuel gas supply selection unit that selects whether to supply a fuel gas to the fuel cell; and a purge selection unit that selects whether to discharge fuel exhaust gas from the fuel cell. ,
A tank for storing at least a part of the oxidizing agent, an oxidizing agent introduction selecting means for selecting whether or not to supply the oxidizing agent to the tank, and supplying the oxidizing agent in the tank to at least a part of the fuel gas system Purge gas supply selecting means for selecting whether or not to perform, a purge gas system branched from between the compression means and the humidifying means and connected downstream of the fuel gas supply selecting means,
During system operation, when the pressure in the vicinity of the branch point branching from the compression unit and the humidifying unit to the purge gas system becomes higher than the pressure in the tank, an oxidizing agent is introduced into the tank,
A fuel cell system, wherein at least part of the fuel gas system is purged by using an oxidant stored in the tank when the system is stopped.

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