JPH11329472A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system, capable of eliminating poisoning of an electrode catalyst by using a small-sized, practical device. SOLUTION: In normal operation, high-purity hydrogen is separated from part of a reformed gas made by a reformer 2 by using a hydrogen separation film 14 and stored in a tank 15, power generated by a fuel cell is compared with a previously memorized reference value, and, when a drop from the reference value is more than a fixed value, deterioration of an electrode catalyst is judged to have happened, the amount of power generated is reduced, and poisoning eliminating operation is performed by using the high-purity hydrogen only. When degradation of the electrode catalyst of the fuel cell has occurred, the degradation can be eliminated by surely performing the poisoning eliminating operation. Because the amount of hydrogen separated from the refined gas and stored is far smaller than the whole amount of the reformed gas, a small- sized one is enough for the hydrogen separation film for separating high-purity hydrogen, and therefore this system is practicable in terms of volume and cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fuel cell system, and more particularly to a technique for eliminating poisoning of an electrode catalyst by carbon monoxide contained in reformed gas.

[0002]

2. Description of the Related Art Conventional fuel cell systems are disclosed in, for example, JP-A-63-232272 and JP-A-8-314.
No. 42 is disclosed. Hydrogen gas supplied to the fuel cell may use hydrogen stored in a hydrogen cylinder, a hydrogen storage alloy, or the like, but a reformer (catalyst) is used to generate a hydrogen-rich reformed gas from methanol, It may be used as hydrogen gas. However, in the reaction of reforming from methanol, carbon monoxide is also generated in addition to hydrogen, so that the reformed gas contains carbon monoxide. This carbon monoxide is adsorbed by platinum or an alloy containing platinum, which is an electrode catalyst on the fuel electrode side of the fuel cell, and generates a state of deteriorating the function as a catalyst, that is, a so-called poisoned state of the catalyst. For example, since a polymer electrolyte fuel cell is usually operated at about 100 ° C., in order to prevent poisoning of the electrode catalyst by carbon monoxide contained in the reformed gas, the carbon monoxide concentration is 10 ppm. It is desirable that: However, when reducing carbon monoxide in the reformed gas by selective oxidation or the like, in order to reduce the carbon monoxide to 100 ppm or less, the removal device becomes large and becomes unsuitable for mounting on a vehicle or the like. The problem is that the amount of hydrogen that is produced increases and the amount of hydrogen that can be obtained from the same raw material substantially decreases.

[0003] As described above, when a reformed gas having a carbon monoxide concentration exceeding 100 ppm is supplied to a polymer electrolyte fuel cell to generate power, the performance gradually decreases due to poisoning, and the power generation amount is reduced. Decrease. JP-A-63-23227
In the invention described in Japanese Patent Publication No. 2 (1995), a sensor for detecting the concentration of carbon monoxide is provided, and when the concentration of carbon monoxide becomes high, the temperature of the fuel cell is raised to increase the allowable concentration of monoxide of the fuel cell. To prevent poisoning. Further, in the invention described in JP-A-8-31442, when the poisoning state is detected by the temperature sensor and the catalyst is determined to be in the poisoning state, the carbon monoxide concentration becomes relatively low. By flowing low reformed gas into the fuel cell,
It is configured to eliminate poisoning.

[0004]

As described above, in the fuel cell using the reformed gas, there is a problem that the electrode catalyst is poisoned by carbon monoxide contained in the reformed gas and the power generation performance is deteriorated. In addition, in order to sufficiently remove carbon monoxide in the reformed gas, the removal device becomes large and becomes unsuitable for mounting on vehicles, or the amount of hydrogen oxidized simultaneously with carbon monoxide increases. However, there is a problem that the amount of hydrogen obtainable from the same raw material is substantially reduced, and various measures have been considered as described above, but a sufficient effect has not always been obtained.

The present invention has been made in order to solve the problems of the prior art as described above, and provides a fuel cell system capable of eliminating the poisoning of the electrode catalyst by using a small and practically suitable device. The purpose is to do.

[0006]

In order to achieve the above object, the present invention is configured as described in the appended claims. That is, in the first aspect of the present invention, during normal operation, high-purity hydrogen is separated and stored from a part of the reformed gas, and the generated power of the fuel cell is compared with a reference value stored in advance. When the decrease from the reference value is equal to or more than a predetermined value, it is determined that the electrode catalyst has deteriorated, the power generation amount is reduced, and the poisoning elimination operation is performed only with high-purity hydrogen. . Therefore, when the electrode catalyst is deteriorated, the poisoning elimination operation can be reliably performed to eliminate the deterioration. Also, since the amount of hydrogen separated and stored from the reformed gas is significantly smaller than the amount of the entire reformed gas,
The size of the hydrogen separation membrane for separating high-purity hydrogen is small, so that it is practically usable in terms of both volume and cost. Insufficient power when the amount of power generation is reduced during operation is temporarily supplied from, for example, a backup secondary battery.

Further, in the invention according to claim 2,
When the power generation in the fuel cell is 0 or very small,
The poison elimination operation is configured to be performed. Therefore, the fuel cell can be exposed to high-purity hydrogen for a long time with a small amount of hydrogen, and the effect of eliminating poisoning can be enhanced.

Further, in the invention according to claim 3,
After the fuel cell stops generating power, the inside of the fuel cell is filled with high-purity hydrogen. Therefore, the poisoning can be sufficiently removed over a long period of time. Also, by leaving the residual pressure of hydrogen gas in the fuel cell, the activity is enhanced,
Poisoning recovery effect can be enhanced.

Further, in the invention according to claim 4,
At high pressure at high load, hydrogen gas is stored, and at low pressure at low load, the stored hydrogen flows into the fuel cell. Therefore, a pressurizing pump is not required, and the partial pressure of hydrogen required for hydrogen separation is determined by the pressure in the primary flow pipe, so that a certain amount or more of unnecessary hydrogen is not stored. Further, a configuration for detecting and determining generated power is not required.

[0010]

According to the present invention, the poisoning of the electrode catalyst can be eliminated, so that the fuel cell can be used even if a reformed gas whose carbon monoxide concentration is a concentration that poisons the fuel cell is used. The effect of being able to drive is obtained. Also, during normal operation, high-purity hydrogen is separated and stored from part of the reformed gas,
In addition, the amount of hydrogen to be separated and stored is significantly smaller than the amount of the entire reformed gas, so the hydrogen separation membrane for separating high-purity hydrogen can be reduced in size, and therefore practical in terms of both volume and cost. It is possible.

According to the second aspect of the present invention, the poisoning elimination operation is performed when the amount of power generation is extremely small, so that the fuel cell can be exposed to high-purity hydrogen for a long time with a small amount of hydrogen, and Poison eliminating effect can be enhanced.

According to the third aspect of the present invention, after the fuel cell is stopped, the inside of the fuel cell is filled with high-purity hydrogen.
Poisoning can be sufficiently removed over a long period of time. In addition, by leaving the residual pressure of hydrogen gas in the fuel cell, the activity can be enhanced and the poisoning recovery effect can be enhanced.

Further, in the invention according to claim 4, there is no need to store more than a certain amount of useless hydrogen, and there is no need for a pressurizing pump, and no need for a configuration for detecting and determining generated power. The configuration is simplified.

[0014]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention. In FIG. 1, a solid line indicates a gas path, and a broken line indicates an electric signal path. First, the configuration will be described. 1 is a polymer electrolyte fuel cell, 2 is a reformer (for example, a catalyst device) that generates a hydrogen-rich reformed gas from methanol, and 3 is a carbon monoxide concentration in the reformed gas. 4 is a methanol tank, 5 is a control device (to be described in detail later), 6 is a control signal, 7 is an air supply system for supplying air (oxygen) to the fuel cell 1, and 11 is a reformed gas. Primary flow path piping leading to fuel cell 1, 12 is primary flow path piping 1
A secondary channel pipe branched from the middle of 1, 13 is a pump provided in the secondary channel pipe 12, 14 is a hydrogen separation membrane, 15 is an accumulate tank, and 16 is a high-purity separated by the hydrogen separation membrane 14. Hydrogen flow path, 17 is a hydrogen separation membrane 14
A flow path of the residual gas that has separated a part of the hydrogen contained therein,
Reference numeral 18 denotes a three-way valve that switches between the separated high-purity hydrogen and normal reformed gas to guide the fuel gas to the fuel cell 1, and 19 denotes a sensor that detects the output voltage and current of the fuel cell 1.

The carbon monoxide reduction device 3 is a simple selective oxidation device or the like for reducing the concentration of carbon monoxide in the reformed gas to about 100 ppm. And that of the price. The air supply system 7 includes a compressor and the like, and supplies necessary oxygen (air) to the fuel cell 1. Further, the control device 5 is configured by an arithmetic device including a CPU, an input / output interface, and the like.
A control signal for controlling the fuel cell system is output based on a vehicle control system signal (eg, accelerator pedal opening). However, in the present embodiment, only a portion related to the poisoning elimination operation will be described.

Next, the operation will be described. Methanol from the methanol tank 4 is converted by the reformer 2 into reformed gas. This reformed gas is relatively easily converted to a carbon monoxide concentration of 10
It is reduced to about 0 ppm. However, at this carbon monoxide concentration, the polymer electrolyte fuel cell 1 is poisoned.
The performance gradually decreases.

The reformed gas flowing through the secondary flow pipe 12 branched from the primary flow pipe 11 is pressurized by a small pump 13 to generate a hydrogen partial pressure difference in a small hydrogen separation membrane 14. Thus, a small amount of high-purity hydrogen is purified from the reformed gas during the normal operation, and stored in the accumulation tank 15. The residual gas from which hydrogen has been separated by the hydrogen separation membrane 14 returns to the primary flow pipe 11 through the flow path 17.

At this time, the amount of hydrogen separated from the reformed gas is:
Since the ratio is small relative to the entire reformed gas, the carbon monoxide concentration of the reformed gas flowing through the primary flow path pipe 11 does not greatly change. In addition, the secondary flow pipe 12
By setting the flow rate flowing through the pump to be small, the pump 13
And the power consumption can be reduced. In addition, since the amount of hydrogen separated by the hydrogen separation membrane 14 is significantly smaller than the total amount of reformed gas, the required separation membrane area can be small, and therefore, the expensive hydrogen separation membrane can be reduced in size and realized inexpensively and compactly as a whole. it can.

FIG. 2 is a flowchart showing a control procedure of the poisoning elimination operation in the apparatus shown in FIG. First, at step S1, the sensor 19 detects the generated voltage and current of the fuel cell 1 and sends them to the control device 5. In the control device 5, the operating state of the fuel cell 1 (the flow rate and pressure of the supplied reformed gas)
Is generated in advance as a map of voltage and current. In step S2, the voltage and current at that time are compared with the values in the map, and when the difference is equal to or more than a predetermined value, that is, when the electrode catalyst is poisoned and the generated power is lower than the supplied gas amount. Goes to step S3. If the degree of poisoning is small, the process returns to step S1.

In step S3, the power generation amount in the fuel cell 1 is reduced by the control signal from the control device 5, and the hydrogen consumption is reduced. The degree of this reduction is reduced to such an extent that it can be operated only with high-purity hydrogen from the accumulation tank 15. If the amount of power generation is reduced in this manner during high-load operation of the vehicle, power may become insufficient.However, since the duration of poisoning operation is short, the insufficient power is supplied to the secondary battery for backup. It is supplemented by temporary release from the fuel cell (a vehicle that is always equipped with the fuel cell). The following control is also performed by a control signal from the control device 5, but in FIG. 1, each control signal is collectively shown as a control signal 6.

Next, in step S4, the three-way valve 18 is switched to supply high-purity hydrogen from the accumulation tank 15 to the fuel cell 1. In step S5, the flow rate of the cooling water of the fuel cell 1 is reduced or stopped, and the amount of heat radiation from the cooling water is reduced, and the flow rate of the air from the air supply system 7 is reduced to the amount of power generation necessary for maintaining the temperature. Reduce to the appropriate flow rate. These processes are performed to operate the fuel cell with a small amount of hydrogen and to maintain the temperature of the fuel cell at a temperature suitable for eliminating poisoning.

By performing the above treatment, it is possible to relatively lengthen the time for exposing the fuel cell to high-purity hydrogen while maintaining the temperature of the fuel cell with a small amount of hydrogen stored in the accumulation tank 15. The poisoning elimination effect. Thereafter, as shown in step S6, when the hydrogen stored in the accumulation tank 15 flows out, the pressure decreases, and the flow stops, the poisoning elimination operation is terminated in step S7, and the process shifts to the normal control. . The stop of the outflow of hydrogen can be detected from the power generated by the fuel cell. Further, the control may be shifted to the normal control after a predetermined time.

As described above, in the first embodiment, during normal operation, high-purity hydrogen is separated and stored from a part of the reformed gas, and the power generated by the fuel cell is stored in advance. When the decrease from the reference value is equal to or greater than the predetermined value, it is determined that the electrode catalyst has deteriorated, the power generation amount is reduced, and the poisoning elimination operation is performed using only high-purity hydrogen. It is composed. Therefore, when the electrode catalyst is deteriorated, the poisoning elimination operation can be reliably performed to eliminate the deterioration. Also, since the amount of hydrogen separated and stored from the reformed gas is significantly smaller than the amount of the entire reformed gas, the hydrogen separation membrane for separating high-purity hydrogen can be reduced in size,
Therefore, it can be practically used in terms of both volume and cost.

Next, FIG. 3 is a flowchart showing a second embodiment of the present invention. In FIG. 3, step S
4 to S7 are the same as those in FIG. 2, except that step S8 is provided instead of steps S1 to S3. In FIG. 1, a signal (required later) of required power = 0 is input to the control device 5 instead of the sensor 19 in FIG. 1, and other parts are the same as those in FIG. 1. Illustration is omitted.

In FIG. 3, in step S8, it is determined whether or not a signal indicating that the amount of power generation required for the fuel cell is 0 (or very small) has been given. Carry out the poison elimination operation. The signal of the required power = 0 is given from a drive control device of the vehicle (not shown, a device that controls the entire drive system based on an accelerator opening signal or the like).

In this embodiment, when the power generation amount of the fuel cell is 0 or very small, the poisoning elimination operation is performed. Therefore, the fuel cell may be exposed to high-purity hydrogen with a small amount of hydrogen for a long time. It is possible to enhance the effect of eliminating poisoning. In addition, there is no burden on the secondary battery for backup. Further, since the start of the poisoning elimination operation is determined based on the signal of the required power = 0 given from the drive control device of the vehicle, the voltage / current detection sensor 19 shown in FIG. 1 becomes unnecessary.

Next, FIG. 4 is a schematic diagram showing a third embodiment of the present invention. In FIG. 4, reference numeral 20 denotes a shut-off valve, and reference numeral 21 denotes a relief valve, which are provided on an anode-side outlet pipe of the fuel cell 1. The shut-off valve 20 is opened and closed by a control signal 6 from the control device 5, and shuts off the anode-side outlet pipe when closed. The relief valve 21 is a safety valve that opens at a pressure equal to or higher than a predetermined value close to the pressure resistance of the fuel cell 1 and allows hydrogen gas to escape. Reference numeral 8 denotes a fuel cell operation stop signal, which is given from the vehicle drive control device. In addition, the same reference numerals as those in FIG.

FIG. 5 is a flowchart showing a control procedure of the poisoning elimination operation in the apparatus of FIG. First, in step S10, it is determined whether or not a fuel cell operation stop signal has been given. If "YES", the flow proceeds to step S11, in which the three-way valve 18 is switched to supply hydrogen gas in the accumulation tank 15 to the fuel tank. Supply to battery 1.

Next, in step S12, it is determined whether or not a predetermined time sufficient for discharging the residual gas of the reformed gas in the fuel cell 1 has elapsed. If "YES", the flow proceeds to step S13. Go and close shutoff valve 20. Therefore, the inside of the fuel cell 1 is filled with high-purity hydrogen gas. At this time, the inside of the fuel cell 1 is provided with a relief valve 21.
As a result, the pressure is maintained at a safe pressure lower than the pressure resistance of the fuel cell.

Next, in step S14, the circulation of the cooling water of the fuel cell is stopped, and the inflow of air from the air supply system 7 is also stopped. Then, the shut-off valve 20
After a lapse of a predetermined time (display is omitted) after closing the three-way valve 18, the three-way valve 18 is closed in step S15, and the above state is maintained.
This state may be maintained until the fuel cell 1 enters the operating state next, or may be configured to be released after a predetermined time.

As described above, in the present embodiment,
After the power generation is stopped, the fuel cell 1 is filled with high-purity hydrogen, so that poisoning can be sufficiently removed over a long period of time. In addition, by leaving the residual pressure of hydrogen gas in the fuel cell, the activity can be enhanced and the poisoning recovery effect can be enhanced.

Next, FIG. 6 is a schematic diagram showing a fourth embodiment of the present invention. In FIG. 6, 22 is a check valve, 2
Reference numeral 3 denotes a pressure adjusting valve, reference numeral 25 denotes a pipe downstream of the pressure adjusting valve 23, reference numeral 26 denotes an anode-side outlet pipe of the fuel cell 1, and the same reference numerals as those in FIG. In FIG. 6, the pump 13 provided in the secondary flow pipe 12 in FIG. 1 is omitted.

The operation will be described below. When the load is high (the fuel cell generates a high output), the flow rate of the reformed gas flowing through the primary flow pipe 11 is increased, and the pressure is set to a relatively high pressure. At times, the flow rate of the reformed gas is reduced, and the pressure is set to a relatively low pressure. Such conditions can be set by the pressure adjusting valve 23.

By setting as described above, when the load is high, a partial pressure of hydrogen is generated around the hydrogen separation membrane 14 due to the pressure in the primary flow pipe 11 and the accumulation tank 15
Stores hydrogen. The check valve 22 is a valve that allows gas to pass only in one direction from the primary flow pipe 11 to the hydrogen separation membrane 14.

On the other hand, at a low load, when the pressure in the primary flow pipe 11, that is, the pressure at the fuel cell inlet, becomes lower than a predetermined value, the three-way valve 18 is switched to release the hydrogen stored in the accumulation tank 15 as fuel. Flow into battery 1. The switching of the three-way valve 18 is performed based on a control signal 6 output from the control device 5 by applying a signal 9 from a pressure sensor (not shown) for detecting the pressure at the fuel cell inlet to the control device 5. Note that the three-way valve 18 is omitted, and when the pressure of the primary flow pipe 11, that is, the pressure of the fuel cell inlet, becomes lower than a predetermined value at a low load, the hydrogen in the accumulation tank 15 is automatically replaced by the fuel cell. 1 may be configured to flow. Such a setting can be set according to conditions such as the pressure loss of the pressure adjusting valve 23 and the pipe 25 downstream of the pressure adjusting valve 23. Further, a valve (not shown) for pressure adjustment may be provided in the anode-side outlet pipe 26 of the fuel cell 1. In the case of this configuration, it is necessary to provide a check valve (not shown) at the outlet of the accumulation tank 15.

As described above, if the pressure of the primary flow pipe 11, that is, the inlet pressure of the fuel cell is set high, the efficiency of the fuel cell alone is improved, and more output is obtained with the same amount of hydrogen in the reformed gas. be able to. Since hydrogen separation is performed using the pressure in the primary flow pipe 11 under a high load, the pressurizing pump 13 shown in FIG.

Since the partial pressure of hydrogen required for hydrogen separation is determined by the pressure in the primary flow pipe 11, the amount of hydrogen stored in the accumulation tank 15 is determined by the pressure in the primary flow pipe 11. Therefore, it is not necessary to store more than a certain amount of useless hydrogen.

Further, when the pressure at the inlet of the fuel cell becomes lower than the set value, the hydrogen in the accumulation tank 15 is released. Therefore, the effect of eliminating poisoning can be enhanced.

Further, since the poisoning elimination operation is started in accordance with the pressure at the fuel cell inlet, a voltage / ammeter for monitoring the performance deterioration of the fuel cell can be omitted. In particular, if the hydrogen in the accumulation tank 15 automatically flows into the fuel cell 1 at a low load, a sensor for detecting the pressure is not required.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of a poisoning elimination operation in the apparatus of FIG. 1;

FIG. 3 is a flowchart showing a second embodiment of the present invention.

FIG. 4 is a schematic view showing a third embodiment of the present invention.

FIG. 5 is a flowchart showing a control procedure of a poisoning elimination operation in the apparatus of FIG. 4;

FIG. 6 is a schematic view showing a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 2 ... Reformer 3 ... Carbon monoxide reduction device 4 ... Methanol tank 5 ... Control device 6 ... Control signal 7 ... Air supply system which supplies air to the fuel cell 1 8 ... Signal of required electric power = 0 9 ... Signal from a sensor for detecting the pressure at the inlet of the fuel cell 11 ... Primary flow path pipe for reformed gas 12 ... Secondary flow path pipe 13 ... Pressurizing pump 14 ... Hydrogen separation membrane 15 ... Accumulate tank 16 ... Hydrogen Flow path 17 ... Remaining gas flow path 18 ... Three-way valve 19 ... Voltage and current sensor 20 ... Shutoff valve 21 ... Relief valve 22 ... Check valve 23 ... Pressure adjustment valve 25 ... Pressure adjustment valve 23 Downstream piping 26 ... Anode outlet piping of fuel cell 1

Claims (4)

[Claims] 1. A reformer for generating a hydrogen-rich reformed gas from fuel, a primary flow pipe for guiding the reformed gas from the reformer to a fuel cell, and a branch from the middle of the primary flow pipe. A pressurizing pump and a hydrogen separation membrane provided in the secondary flow path pipe, a tank storing high-purity hydrogen separated by the hydrogen separation membrane, and a branch of the secondary flow path pipe in the primary flow path pipe A three-way valve that is provided at a portion downstream of the point with a junction with a hydrogen gas flow path pipe from the tank and that switches between the reformed gas and the hydrogen gas provided at the junction and leads to the fuel cell. And detecting the generated power of the fuel cell, comparing the generated power with a reference generated power stored in advance for the fuel supply condition of the fuel cell, and poisoning when the difference is equal to or greater than a predetermined value. And the three-way valve is connected to the hydrogen gas supply side. Fuel cell system characterized by comprising together, and control means for controlling so as to reduce the amount of power generated by the fuel cell, a switch. 2. A reformer for generating a hydrogen-rich reformed gas from fuel, a primary flow pipe for guiding the reformed gas from the reformer to a fuel cell, and a branch from the middle of the primary flow pipe. A pressurizing pump and a hydrogen separation membrane provided in the secondary flow path pipe, a tank storing high-purity hydrogen separated by the hydrogen separation membrane, and a branch of the secondary flow path pipe in the primary flow path pipe A three-way valve that is provided at a portion downstream of the point with a junction with a hydrogen gas flow path pipe from the tank and that switches between the reformed gas and the hydrogen gas provided at the junction and leads to the fuel cell. And control means for switching the three-way valve to the hydrogen gas supply side and controlling the fuel cell to reduce the power generation when the power generation required for the fuel cell is 0 or close to 0. Fuel cell system Temu. 3. A reformer for generating a hydrogen-rich reformed gas from fuel, a primary flow pipe for guiding the reformed gas from the reformer to a fuel cell, and a branch from the middle of the primary flow pipe. A pressurizing pump and a hydrogen separation membrane provided in the secondary flow path pipe, a tank storing high-purity hydrogen separated by the hydrogen separation membrane, and a branch of the secondary flow path pipe in the primary flow path pipe A three-way valve that provides a junction with the hydrogen gas flow path pipe from the tank at a portion downstream of the point and switches the reformed gas and the hydrogen gas provided at the junction to the fuel cell. A shut-off valve provided on an outlet pipe on the anode side of the fuel cell; and when the operation of the fuel cell is stopped, the three-way valve is switched to the hydrogen gas supply side to supply hydrogen gas in a tank to the fuel cell. , Reformed gas residual gas Control means for closing the shut-off valve after a lapse of a predetermined time required for discharge, and controlling the fuel cell to maintain a residual pressure of hydrogen gas in the fuel cell. . 4. A reformer for generating a hydrogen-rich reformed gas from a fuel, a primary flow pipe for guiding the reformed gas from the reformer to a fuel cell, and a branch in the middle of the primary flow pipe. A check valve and a hydrogen separation membrane provided in the secondary flow path piping, a tank storing high-purity hydrogen separated by the hydrogen separation membrane, and a branch of the secondary flow path piping in the primary flow path piping A junction with a hydrogen gas flow path pipe from the tank, provided at a portion downstream from the point, wherein hydrogen is separated by the hydrogen separation membrane when the gas pressure in the primary flow path pipe is high. A fuel cell system wherein the hydrogen gas in the tank flows into the fuel cell when a sufficient hydrogen partial pressure is generated and the gas pressure in the primary flow path pipe is lower than a predetermined value. .