JP2002343386A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system enabled to realize a more stable and safer operation when operating, and enabled to realize a safer inert gas purge when stopping the operation. SOLUTION: A residual fuel gas flow path 25 and a combustion gas flow path 26 supplying respective gases to a combustion device 24 burning residual fuel gas exhausted from a fuel cell 21 and fuel gas supplied to outside, are installed. An electromagnetic valve 28, passing and blocking the supply of combustion gas by opening and closing the combustion gas flow path, a proportion valve 29 adjusting the flow volume of the residual combustion gas, and a check valve 30 preventing the back flow of the residual fuel gas, are mounted to the combustion gas flow path 26 from the upstream in this sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system for generating electric power using a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art A conventional fuel cell system will be described below with reference to the drawings.

As shown in FIG. 3, a conventional fuel cell system comprises a polymer electrolyte fuel cell 1 for generating electric power using a fuel gas and an oxidizing gas, and a steam reforming of raw material such as natural gas. A fuel gas generating unit 2 for generating a hydrogen-rich gas and supplying it to the fuel cell 1, a fuel-side humidifier 3 for humidifying the fuel gas supplied to the fuel cell 1, and a residual fuel gas discharged from the fuel cell 1; A combustor 4 for burning the combustion gas, a residual fuel gas passage 5 for supplying the residual fuel gas to the combustor 4,
A combustion gas flow path 6 for supplying combustion gas to the combustor 4 and a raw material gas flow path 7 for supplying raw material to the fuel gas generator 2 are provided.

The combustion gas passage 6 has a combustion gas passage 6.
And a proportional valve 9 for adjusting the combustion gas flow rate. Further, the source gas flow path 7 is provided with a nitrogen supply port 10 for supplying nitrogen and an electromagnetic valve 11 for opening and closing the source gas flow path 7.

The fuel gas generated by the fuel gas generator 2 contains water vapor, carbon dioxide, and a trace amount of carbon monoxide in addition to hydrogen. The fuel gas generated by the fuel gas generator 2 is humidified by the fuel humidifier 3 using water. The humidified fuel gas is supplied to the fuel cell 1 to generate power.

From the fuel cell 1, a mixed gas of hydrogen, water vapor, carbon dioxide, and carbon monoxide, which has not been used for power generation, is discharged. The discharged residual fuel gas is supplied to the combustor 4 through the residual fuel gas passage 5. Combustion gas is also supplied to the combustor 4 through a combustion gas passage 6.

The combustor 4 is for promoting the reforming reaction of the fuel gas generator 2, and when starting or at the time of low power generation, etc., when the residual fuel gas is large, only the residual fuel gas is burned. The temperature of the portion in the generation section 2 that controls the reforming reaction is maintained. Further, when the power generation is started and the temperature cannot be maintained only by the residual fuel gas, the temperature is maintained by burning both the residual fuel gas and the combustion gas. That is, when burning only the residual fuel gas, the solenoid valve 8 and the proportional valve 9 are closed. When combustion gas is also combusted, the solenoid valve 8 is opened and the valve opening of the proportional valve 9 is adjusted to adjust the combustion gas flow rate.

At the end of operation of the combustion cell system,
The supply of the raw material is stopped by closing the electromagnetic valve 11, nitrogen is supplied from the nitrogen supply port 10, and the fuel gas flow path including the fuel cell 1 and the fuel gas generator 2 is purged with nitrogen.

[0009]

In the above conventional example,
When the combustor 4 is burning only the residual combustion gas, the solenoid valve 8 and the proportional valve 9 are closed. The remaining fuel gas contains hydrogen, water vapor, carbon dioxide, and carbon monoxide that have not been used for power generation. Most of the remaining fuel gas is in the combustor 4
However, a part of the fuel gas diffusely flows into the combustion gas flow path 6 from the junction of the residual fuel gas flow path 5 and the combustion gas flow path 6 and reaches the proportional valve 9. As a result, the water vapor contained in the residual fuel gas is condensed on the proportional valve 9. This causes a loss of stable supply of the combustion gas flow rate during the supply of the combustion gas, and also causes a failure of the proportional valve 9.

In the conventional nitrogen purge, the solenoid valve 11 is closed and nitrogen is supplied from the nitrogen supply port 10. During operation, pressure loss in the fuel gas flow path is large due to various reactions such as steam reforming in the fuel gas generation unit 2, humidification in the fuel-side humidifier 3, and combustion in the combustor 4. The gauge pressure at the inlet of the fuel gas generator 2 during operation is about 10 to 20 kPa. Therefore, when supplying nitrogen from the nitrogen supply port 10 immediately after the system operation, supply is performed at a high discharge pressure. When a pressure of about 10 kPa is applied to the secondary port of the current electromagnetic valve 11, even if the valve is closed, the valve opens due to the pressure and flows backward. As a result, nitrogen is mixed in the source gas flow path 7 upstream of the solenoid valve 11.

In view of the above-mentioned problems of the conventional fuel cell system, the present invention provides a more stable and safer combustor for combusting residual fuel gas and combustion gas during operation of the fuel cell system. It is an object of the present invention to provide a fuel cell system capable of realizing efficient combustion.

It is another object of the present invention to provide a fuel cell system which can realize safer inert gas purging at the end of fuel cell system operation.

[0013]

Means for Solving the Problems The first invention (claim 1)
A) a fuel generating means for reforming a raw material to generate a hydrogen-rich fuel gas, a polymer electrolyte fuel cell for generating power using the fuel gas and the oxidizing gas, and A combustor for burning one or both of the residual fuel gas and the combustion gas to be discharged, a residual fuel gas flow path for supplying the residual fuel gas to the combustor, and supplying the combustion gas to the combustor A combustion gas flow path, and a combustion gas flow rate adjusting means provided in the combustion gas flow path to adjust a flow rate of the combustion gas; and a junction of the residual fuel gas flow path and the combustion gas flow path, A fuel cell system in which a residual fuel gas check valve is provided in the combustion gas flow path between the combustion gas flow rate adjusting means.

According to a second aspect of the present invention (corresponding to claim 2), the residual fuel gas check valve is a solenoid valve, and the solenoid valve has a closing function against inflow from the direction of the junction. 1 is a fuel cell system according to a first invention.

A third aspect of the present invention (corresponding to claim 3) is a fuel generating means for reforming a raw material to generate a hydrogen-rich fuel gas, and a solid-state for generating power using the fuel gas and the oxidizing gas. A polymer fuel cell, a raw material flow path for supplying a raw material to the fuel generating means, an inert gas supply port provided in the raw material flow path, for supplying an inert gas to the raw material flow path, The inert gas check valve provided in a portion of the raw material flow path upstream of the inert gas supply port, when the operation of the system is completed, the fuel generation means, the fuel gas flow path and the fuel cell This is a fuel cell system for purging with an inert gas.

According to a fourth aspect of the present invention (corresponding to claim 4), the inert gas check valve is a solenoid valve, and the solenoid valve has a closing function against inflow from the direction of the inert gas supply port. It is a fuel cell system of the third invention having the following.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram showing a fuel cell system according to Embodiment 1 of the present invention. The fuel cell system according to the present embodiment is a polymer electrolyte fuel cell 2 that generates power using a fuel gas and an oxidizing gas.
1, a fuel gas generating unit 22 that generates a hydrogen-rich gas by steam reforming a raw material such as natural gas and supplies it to a fuel cell 21, and a fuel-side humidifier that humidifies the fuel gas supplied to the fuel cell 21 23, a combustor 24 for burning the residual fuel gas and the combustion gas discharged from the fuel cell 21, a residual fuel gas flow path 25 for supplying the residual fuel gas to the combustor 24,
A combustion gas passage 26 for supplying combustion gas to the combustor 24;
Source gas flow path 27 that supplies a source material to fuel gas generation unit 22
Is provided.

The combustion gas passage 26 has a solenoid valve 28 for opening and closing the combustion gas passage to supply and shut off the combustion gas, a proportional valve 29 for adjusting the flow rate of the combustion gas, and a residual valve for preventing the backflow of the remaining combustion gas. The fuel gas check valve 30 is provided.

The fuel gas generated by the fuel gas generator 22 contains water vapor, carbon dioxide, and a trace amount of carbon monoxide in addition to hydrogen. The fuel gas generated by the fuel gas generator 22 is
By using water in the fuel-side humidifier 23, humidification is performed to an appropriate humidity. The humidified fuel gas is supplied to the fuel cell 21 to generate power. From the fuel cell 21, a mixed gas of hydrogen, water vapor, carbon dioxide, and carbon monoxide that has not been used for power generation is discharged. The discharged residual fuel gas is supplied to the combustor 24 through the residual fuel gas passage 25. Combustion gas is also supplied to the combustor 24 through a combustion gas passage 26.

The combustor 24 is for accelerating the reforming reaction of the fuel gas generating section 22. When the residual fuel gas is large at the time of starting or at the time of low power generation, the combustor 24 burns only the residual fuel gas.
The temperature of the portion that controls the reforming reaction in the fuel gas generator 22 is maintained. Further, when the power generation is started and the temperature cannot be maintained only by the residual fuel gas, the temperature is maintained by burning both the residual fuel gas and the combustion gas.

That is, when only the residual fuel gas is burned, the solenoid valve 28, the proportional valve 29 and the residual fuel gas check valve 30 are closed. When both the combustion gas and the residual fuel gas are burned, the solenoid valve 8 and the residual fuel gas check valve 30 are opened, and the opening of the proportional valve 29 is adjusted to adjust the combustion gas flow rate.

In the present embodiment, the combustor 24 is a combustor for accelerating the reforming reaction of the fuel gas generator 22. However, the combustor 24 uses hot water for heat exchange by exchanging combustion heat with water.
A combustor utilizing heat for heating or the like may be used.

With the configuration of the fuel cell system according to the present embodiment, when only the residual fuel gas is burned in the combustor 24, the solenoid valve 28, the proportional valve 29 and the residual fuel gas check valve 30 are closed. I do. Therefore, the residual fuel gas cannot flow back upstream of the residual fuel gas check valve 30 nor can it diffusely flow.

As a result, water droplets do not condense on the proportional valve 29, so that a stable supply of the combustion gas flow rate can be realized during the subsequent supply of the combustion gas, and the failure of the proportional valve 29 due to water droplets can be prevented. Naturally, backflow of the residual fuel gas upstream of the solenoid valve 28 and the proportional valve 29 does not occur.

The backflow and diffusive inflow of the residual fuel gas into the combustion gas passage 26 are caused by the pressure at the outlet of the proportional valve 29 at the junction of the residual fuel gas passage 25 and the combustion gas passage 26. This is more pronounced in conventional fuel cell systems when the pressure is higher. Therefore, an electromagnetic valve is used as the residual fuel gas check valve 30 so that the combustion gas that has passed through the proportional valve 29 enters the electromagnetic valve from the OUT port of the electromagnetic valve, exits from the IN port, and is supplied to the combustor 24. Installation is effective.

That is, since the solenoid valve is disposed in the forward direction with respect to the flow of the residual fuel gas, it is possible to prevent the residual fuel gas from flowing backward even when the pressure of the residual fuel gas increases.

(Embodiment 2) FIG. 2 is a configuration diagram showing a fuel cell system according to Embodiment 2 of the present invention. The fuel cell system according to the second embodiment includes a polymer electrolyte fuel cell 21 that generates power using a fuel gas and an oxidizing gas, and a process in which a raw material such as natural gas is subjected to steam reforming to generate a hydrogen-rich gas. And a fuel-side humidifier 23 for humidifying the fuel gas supplied to the fuel cell 21, and a residual fuel for discharging the fuel gas not used for the reaction from the fuel cell 21. Gas flow path 25
And a raw material gas flow path 27 that supplies a raw material to the fuel gas generation unit 22.

The source gas passage 27 has an inert gas supply port 31 for supplying an inert gas, and an electromagnetic valve 32 for opening and closing the source gas passage 27 to supply and shut off the source gas.
And an inert gas backflow prevention valve 33 for preventing backflow of the inert gas in the source gas flow path upstream of the inert gas supply port.

At the end of the operation of the fuel cell system, first, the solenoid valve 32 and the inert gas check valve 33 are closed. Next, an inert gas is supplied from the inert gas supply port 31,
Fuel gas generator 22, fuel humidifier 23, fuel cell 21
And the fuel gas flow path is purged with an inert gas.

With the configuration of the fuel cell system according to the present embodiment, the inert gas check valve 33 is closed even when the inert gas discharge pressure is high immediately after the operation of the fuel cell system is stopped. Therefore, the pressure on the outlet side with respect to the raw material gas of the electromagnetic valve 32 does not increase, and the valve of the electromagnetic valve 32 in the closed state does not open. That is, it is possible to prevent nitrogen from being mixed upstream of the electromagnetic valve 32 in the source gas flow path 27.

The backflow of the inert gas occurs in the conventional system when the pressure at the junction between the inert gas supply port 31 and the source gas flow path 27 is higher than the pressure at the inlet of the solenoid valve 32. Occur. Therefore, an electromagnetic valve is used as the inert gas check valve 33 so that the raw material that has passed through the electromagnetic valve 32 enters the electromagnetic valve from the OUT side port of the electromagnetic valve, exits from the IN side port, and is supplied to the fuel gas generation unit 22. Is effective. That is, since the solenoid valve is installed in the forward direction with respect to the flow of the inert gas, the reverse flow of the inert gas can be prevented even when the pressure of the inert gas increases.

[0033]

As is apparent from the above description,
ADVANTAGE OF THE INVENTION This invention can provide the fuel cell system which can implement | achieve more stable and safe combustion of the combustor which burns a residual fuel gas and a combustion gas at the time of operation of a fuel cell system.

Further, it is possible to provide a fuel cell system capable of realizing safer inert gas purging at the end of operation of the fuel cell system.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a fuel cell system according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram illustrating a fuel cell system according to Embodiment 2 of the present invention.

FIG. 3 is a configuration diagram showing a conventional polymer electrolyte fuel cell system.

[Explanation of symbols]

 1, 21 Fuel cell 2, 22 Fuel gas generator 3, 23 Fuel humidifier 4, 24 Combustor 5, 25 Residual fuel gas flow path 6, 26 Combustion gas flow path 7, 27 Source gas flow path 8, 11, 28, 32 Solenoid valve 9, 29 Proportional valve 10 Nitrogen supply port 30 Residual fuel gas check valve 31 Inert gas supply port 33 Inert gas check valve

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tetsuya Ueda 1006 Kazuma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference)

Claims (4)

[Claims] 1. A fuel generating means for reforming a raw material to generate a hydrogen-rich fuel gas, a polymer electrolyte fuel cell for generating electric power by using the fuel gas and an oxidizing gas, and A combustor for burning one or both of the residual fuel gas and the combustion gas to be discharged, a residual fuel gas flow path for supplying the residual fuel gas to the combustor, and supplying the combustion gas to the combustor A combustion gas flow path, and a combustion gas flow rate adjusting means provided in the combustion gas flow path to adjust a flow rate of the combustion gas; and a junction of the residual fuel gas flow path and the combustion gas flow path, A fuel cell system, wherein a residual fuel gas check valve is provided in the combustion gas flow path between the combustion gas flow rate adjusting means. 2. The fuel cell system according to claim 1, wherein the residual fuel gas check valve is an electromagnetic valve, and the electromagnetic valve has a closing function against inflow from the direction of the junction. 3. A fuel generating means for reforming a raw material to generate a hydrogen-rich fuel gas, a polymer electrolyte fuel cell for generating power using the fuel gas and an oxidizing gas, and A raw material flow path for supplying to the generating means, an inert gas supply port provided in the raw material flow path for supplying an inert gas to the raw material flow path, and a raw material flow path upstream of the inert gas supply port. A fuel cell system comprising: an inert gas check valve provided in a portion thereof; and purging the fuel generating means, the fuel gas flow path, and the fuel cell with the inert gas when the operation of the system is completed. 4. The fuel cell system according to claim 3, wherein the inert gas check valve is a solenoid valve, and the solenoid valve has a closing function against inflow from the direction of the inert gas supply port.