JP2000036311A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost fuel cell system which is safe, small and light, has high power generating efficiency, manages with a small power consumption in a valve, and need not use of a check valve. SOLUTION: Motor-driven valves 11b and 11c are installed on a gas pipe line to be opened and closed for gas such as an unused hydrogen gas pipe line 9a and air pipe line 9b connecting a fuel cell stack 10 to a burner 6 so as to eliminate necessity for the feed of current when the valve is open, and a motor-driven valve 11a is installed between air pipe lines 9d and 9f to couple a compressor 83 with at least a reformer 33 and CO reducing part 34 to control passing of compressed air so that necessity for provision of a check valve is eliminated. Thus an intended fuel cell system is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a fuel cell system.

[0002]

2. Description of the Related Art A fuel cell includes a reformer that generates a reformed gas containing hydrogen as a main component from a hydrocarbon fuel as a fuel;
A fuel cell stack that generates power using the reformed gas as fuel,
It is composed of a control device for controlling them and various gas pipelines.

[0003] As the gas line, in addition to the gas lines for the reformed gas and the oxidizing gas, gas lines for an inert gas for purging, air for control and the like are conceivable.

[0004] The reaction for producing reformed gas in the reformer is as follows:
It is an oxidation reaction and needs to supply oxygen. The oxygen is supplied by compressing an oxidizing gas such as air by a compressor.

[0005] The reformed gas generated in the reformer and the oxidizing gas such as air compressed by a compressor are sent to a fuel cell stack and used for power generation by an electrochemical reaction. Is discharged.

When the fuel cell system is stopped, an inert gas such as nitrogen is sent to the fuel cell stack to purge the reformed gas remaining in the fuel cell stack.

[0007] These gases are sent through respective gas pipelines, and a gas valve is required to control the opening and closing of the gas.

The prior art is disclosed in Japanese Patent Application Laid-Open No. 7-272737.
Japanese Patent Application Laid-Open Publication No. Hei 11 (1995) discloses an embodiment using an electromagnetic valve and a check valve.

FIG. 3 is a sectional view of a general electromagnetic valve 100. The valve 101, the electromagnetic coil 102, and the movable core 1 are shown in FIG.
03, comprised of a spring 104. The valve 10
1 and the movable iron core 103 are connected.

When the electromagnetic valve 100 is open,
When a current flows through the electromagnetic coil 102 and the movable core 10
3 and the valve 10 connected to the armature 103
1 is moved upward in the figure, and gas entering from the gas inlet 105 is sent to the gas outlet 106.

On the other hand, when the electromagnetic valve 100 is closed, when the current flowing through the electromagnetic coil 102 is stopped,
The force for pulling the movable iron core 103 toward the electromagnetic coil 102 disappears, and the valve 101 is moved downward in the drawing by the force of the spring 104 to be pressed against the gas pipeline opening / closing portion 107 to block the passage of gas.

The gas outlet 106 of the electromagnetic valve 100
If the pressure becomes higher than the pressure at the gas inlet 105, the valve 101 overcomes the spring force of the spring 104 to open the valve 101, and the gas flows backward.

When the fuel cell system is stopped and not operating after being operated, the pressure of hydrogen in the reformer may increase. When the pressure of the hydrogen increases, the hydrogen only flows back through the oxidizing gas pipe for sending the oxidizing gas from the compressor to the reformer by the electromagnetic valve alone. There is a risk of leaking fire inside, which is an important safety issue.

In order to prevent the backflow, it is common to install the solenoid valve 100 and the check valve of FIG. 4 or 5 in series as in the prior art.

[0015]

However, in the conventional electromagnetic valve, it is necessary to keep the current flowing through the electromagnetic coil 102 in order to maintain the open state, which leads to an increase in power consumption.

[0016] Increasing the power consumption causes the power generated by the fuel cell system to be consumed by itself, thereby lowering the power generation efficiency of the fuel cell system. In the case of a vehicle-mounted fuel cell system such as an automobile, the electric power is limited, and a decrease in power generation efficiency is a particularly important problem.

In a place where the pressure on the valve outlet side is likely to increase, it is necessary to provide an electromagnetic valve and a check valve in series, leading to an increase in cost and an increase in volume and weight.

Further, since the check valve involves a pressure loss,
The compressor has to be enlarged or the output of the compressor has to be increased, which leads to an increase in cost, an increase in volume and weight, and an increase in power consumption.

The present invention has been made to solve the above-mentioned problems and provides a fuel cell system having a high power generation efficiency without the need to flow a current even when the valve is in an open state. The present invention provides a small, lightweight, low-cost, high power generation efficiency fuel cell system that can prevent backflow, and a small, lightweight, safe and oxidant gas that can be supplied to a reformer without using a check valve. Provide low cost and high power generation efficiency fuel cell system.

[0020]

Means for Solving the Problems In order to solve the above technical problems, the technical means (hereinafter referred to as first technical means) taken in claim 1 of the present invention is a hydrocarbon fuel. A reformer for generating a reformed gas containing hydrogen as a main component, a fuel cell stack for generating electricity from the reformed gas and the oxidizing gas, and a gas line for supplying the reformed gas and the oxidizing gas In the fuel cell system, a motor-driven valve is provided on the gas pipeline.

The effects of the first technical means are as follows.

That is, since the open state can be maintained even when the current is stopped, the current is not consumed in the open state, so that the power consumption is small and the power generation efficiency of the fuel cell can be increased.

In order to solve the above-mentioned technical problem, the technical means (hereinafter referred to as second technical means) taken in claim 2 of the present invention is that the motor-driven valve is connected to a gas of the valve. 2. The fuel cell system according to claim 1, wherein the pressure on the outlet side is provided on a gas pipeline higher than the pressure on the gas inlet side.

The effect of the second technical means is as follows. That is, the valve does not open even if pressure is applied to the gas outlet side of the motor-driven valve, so that a check valve is not required, so that a fuel cell system having a small size, light weight, low cost, and high power generation efficiency can be obtained. Having.

In order to solve the above technical problem, a technical means (hereinafter referred to as a third technical means) taken in claim 2 of the present invention is that the motor driven valve is connected to the reformer. 2. The fuel cell system according to claim 1, wherein the fuel cell system is provided on an oxidizing gas pipe that sends the oxidizing gas compressed by a compressor.

The effects of the third technical means are as follows. That is, since the valve does not open even if pressure is applied to the gas outlet of the motor-driven valve, flammable hydrogen can be prevented from leaking into the oxidizing gas, so that it is safe, small, lightweight, low-cost and This has the effect of producing a fuel cell system with high power generation efficiency.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings.

FIG. 1 shows a solid polymer electrolyte fuel cell system according to an embodiment of the present invention, which is mounted on a vehicle such as an automobile.

This fuel cell system comprises a methanol tank 1 for storing methanol as a hydrocarbon fuel, a water tank 2, a reformer 3, a fuel cell stack 10, a combustion burner 6, a turbo assist compressor 8, and a motor-driven valve. It comprises 11a, 11b, 11c and various gas pipelines.

As the hydrocarbon fuel, not only methanol but also many other hydrocarbon fuels such as gasoline and natural gas can be used.

The reformer 3 is a device for generating a reformed gas containing hydrogen as a main component from methanol and water. The reformer 3 evaporates methanol and water, and burns methanol to heat the evaporator 32. Combustion unit 31 and evaporation unit 3
A reforming section 33 for converting the methanol and water evaporated in step 2 into a reformed gas containing hydrogen as a main component, and a CO reducing section 34 for reducing CO from the reformed gas coming out of the reforming section 33. Have been.

The reformed gas discharged from the CO reduction unit 34 is sent to the combustion burner 6 by switching the three-way switching valve 5 or sent to the fuel cell stack 10.

The fuel cell stack 10 generates electric power by an electrochemical reaction using the reformed gas and air which is an oxidizing gas sent from the turbo assist compressor 8.

In the combustion burner 6, the three-way switching valve 5
Gas or fuel cell stack 10 sent by switching
The fuel cell stack 10 burns the unused hydrogen discharged through the unused hydrogen gas pipe 9a as fuel, and the air discharged through the air pipe 9b from the fuel cell stack 10 as a fuel.

The turbo assist compressor 8 comprises a turbine 81, a motor 82 and a compressor 83.

The turbine 81 is connected to the combustion burner 6 by an exhaust gas line 9c, and rotates by the energy of the exhaust gas from the combustion burner 6.

The compressor 83 is connected to the turbine 8
1 and is rotated by the power of the motor 82 to compress the air.

The air outlet 84 of the compressor 83 and the motor-driven valve 11a are connected via an air line 9d. The motor-driven valve 11a and the reformer 33
Is a branch air line 9f, a flow control valve 12a, an air line 9
g, the motor-operated valve 11
a and the CO reduction unit 34 are connected via the branch air line 9f, the flow control valve 12b, and the air line 9h.

The air outlet 84 of the compressor 83 and the fuel cell stack 10 are connected via an air line 9d and an air line 9e branched from the air line 9d.

The reformed gas outlet 10a of the fuel cell stack 10 and the combustion burner 6 are connected by an unused hydrogen gas line 9a, and a motor-driven valve 11b is provided on the unused hydrogen gas line 9a. .

The air outlet 10 of the fuel cell stack 10
b and the combustion burner 6 are connected by an air line 9b, and a motor-driven valve 11c is provided on the air line 9b.

In the present embodiment, the same methanol tank 1 is used for the methanol as the raw material of the reformed gas containing hydrogen as a main component and the methanol of the fuel in the combustion section 31 of the reformer 3 to be sent to the fuel cell stack 10. I have. The above-mentioned raw material of the reformed gas and the methanol of the fuel in the combustion section 31 may be in different tanks.

The methanol supplied from the methanol tank 1 to the combustion section 31 is burned using the air supplied by the blower 4 as an auxiliary agent.

The methanol and water supplied from the methanol tank 1 and the water tank 2 to the evaporator 32 are
The heat generated in step evaporates into gas and is sent to the reforming unit 33.

The methanol and water vapor sent from the evaporator 32 to the reformer 33 are mixed with the air sent from the compressor 83 via the motor-driven valve 11a, and are mixed with a catalyst (for example, Cu-Zn). A reformed gas mainly composed of hydrogen by a catalyst or the like.

The reformed gas contains 0.5 to 1% of CO. When sent to the fuel cell stack 10 as it is, the reformed gas poisons the electrode catalyst of the fuel cell stack 10 and significantly lowers the power generation performance of the fuel cell. .

Therefore, the reformed gas discharged from the reforming section 33 is C
It is sent to the O reduction unit 34. The reformed gas sent to the CO reduction unit 34 is mixed with air sent from the compressor 83 via the motor-driven valve 11a, and selectively oxidizes CO by a catalyst (for example, a Pt catalyst). The fuel cell stack 10 by reducing the CO concentration to 10 ppm or less.
Sent to

Immediately after the start-up, the temperature of the reformer 3 has not risen sufficiently and the CO concentration has not fallen below 10 ppm even after passing through the CO reduction section 34. And sent to the combustion burner 6.

The fuel cell stack 10 generates power using hydrogen in the reformed gas and air sent from the compressor 83 via the air line 9e.

In the fuel cell stack 10, hydrogen is 10
It is not used at 0%, but is about 80%. The gas containing unused hydrogen is sent to the combustion burner 6 via the unused hydrogen gas line 9a. Motor-driven valve 1 provided on the unused hydrogen gas line 9a
1b controls the passage of unused hydrogen by opening and closing.

Since excess air is sent to the fuel cell stack 10, unused air remains, and unused air is transferred to the combustion burner 6 via the air line 9b.
And sent to a combustion aid. A motor-driven valve 11c provided on the air line 9b controls the passage of air by opening and closing.

In the combustion burner 6, the reformed gas sent from the CO reduction unit 34 by switching the three-way switching valve 5 or the unused hydrogen sent from the fuel cell stack 10 via the unused hydrogen gas pipe 9a. And the exhaust gas is sent to the turbine 81 of the turbo assist compressor 8 via the exhaust gas line 9c to rotate the turbine 81.

The compressor 83 is rotated by the turbine 81 and the motor 82, compresses air and sends the compressed air to the motor-driven valve 11a via the air line 9d. The motor-driven valve 11a controls the passage of air. Is done.

When the motor-driven valve 11a is open, the compressed air is supplied to the reforming section 33 through the air line 9f, the flow control valve 12a, and the air line 9g.
f, is supplied to the CO reduction unit 34 through the flow control valve 12b and the air pipe 9h.

The compressed air is supplied to the fuel cell stack 10 via an air line 9e branched from the air line 9d.

FIG. 2 is a sectional view of the motor-driven valves 11a, 11b and 11c according to the embodiment of the present invention.
1, a rotor shaft 22, a nut 23, a valve 24, and a valve shaft 25.

A nut 23 is fixed to a rotor shaft 22 of the motor 21. The valve 24 and the valve shaft 25 are integral with each other.
Is cut off, and a portion 25b penetrating the valve cover 26 is D-cut.

A D hole is formed at the center of the valve cover 26, and a shaft D cut portion 25b of the valve 24 is in contact therewith and penetrates. For this reason, the valve shaft 25 can move linearly but cannot rotate.

When the motor 21 rotates clockwise as viewed from the P direction, the rotor shaft 22 and the nut 23 rotate clockwise as viewed from the P direction, and the valve shaft 25 stops rotating at the D hole of the valve cover 26. 2, the valve 24 integral with the valve shaft 25 also moves upward in FIG. 2, and the air inlet 27 and the air outlet 28 are in an open state.

On the other hand, when the motor 21 rotates counterclockwise as viewed from the P direction, the rotor shaft 22 and the nut 2
3 rotates counterclockwise when viewed from the P direction,
5 moves downward in FIG. 2 because the rotation is stopped at the D hole of the valve cover 26, and the valve 24 integrated with the valve shaft 25 also moves downward in FIG.
To shut off.

Even if a force is applied from the valve side when the energization is stopped in the open state or the closed state, a linear force cannot be changed to a rotating force, so that the open state or the closed state is maintained. it can.

Accordingly, the valve 24 does not open even if the pressure at the air outlet 28 rises in the closed state of the motor-driven valve.
There is no need to provide a check valve.

That is, in order to maintain the open state or the closed state, it is not necessary to keep the current flowing, and no check valve is required.

The use of the motor-driven valve is not limited to the use location of the present embodiment, and can be used in a place where opening and closing of a gas pipe such as an inert gas pipe for purging is required.

As a result, the motor-driven valve 11a,
11b and 11c do not require power consumption even in the open state, so that a fuel cell system with high power generation efficiency can be realized.

Even if the pressure in the reforming section 33 and the CO reducing section 34 rises, the reforming section 3 is driven only by the motor-driven valve 11a.
3. The reformed gas containing hydrogen as a main component of the CO reducing unit 34 can be shut off, and the reformed gas does not flow backward and leaks into the atmosphere, which is safe.

In addition, there is no need to provide a check valve, so that the fuel cell system is small, light, and low in cost. In addition, since there is no pressure loss due to the check valve, the output of the compressor 83 can be reduced and the power consumption of the motor 82 can be reduced. And a fuel cell system with high power generation efficiency can be realized.

[0068]

As described above, the present invention relates to a reformer for generating a reformed gas containing hydrogen as a main component from a hydrocarbon fuel, and a fuel cell stack for generating power from the reformed gas and an oxidizing gas. In the fuel cell system comprising a gas pipe for supplying the reformed gas and the oxidizing gas, a motor-driven valve is provided on the gas pipe, so that the valve is in an open state. However, a fuel cell system with high power generation efficiency without consuming power can be realized.

By providing the motor-driven valve on a gas pipe where the pressure on the gas outlet side may be higher than the pressure on the gas inlet side, the check valve is eliminated and the fuel cell system is compact, lightweight and low-cost. Can be realized.

Further, by providing the motor-driven valve on the oxidizing gas pipe for sending the oxidizing gas compressed by the compressor to the reformer, the reformed gas mainly containing flammable hydrogen flows backward. Thus, a safe, compact, lightweight and low-cost fuel cell system can be realized without leaking into the oxidizing gas.

[Brief description of the drawings]

FIG. 1 is a solid polymer electrolyte fuel cell system according to an embodiment of the present invention.

FIG. 2 is a sectional view of a motor-driven valve according to an embodiment of the present invention.

FIG. 3 is a sectional view of a conventional electromagnetic valve.

FIG. 4 is a sectional view of a first example of a check valve used in the prior art.

FIG. 5 is a sectional view of a second example of a check valve used in the prior art.

[Explanation of symbols]

3: Reformer 6: Combustion burner 9a: Unused hydrogen gas line 9b, 9d, 9f, 9g, 9h: Air line (oxidizing gas line) 10: Fuel cell stack 11a, 11b, 11c: Motor drive Type valve 33 ... Reforming unit 34 ... CO reduction unit 83 ... Compressor

Claims (3)

[Claims] 1. A reformer that generates a reformed gas containing hydrogen as a main component from a hydrocarbon-based fuel, a fuel cell stack that generates power from the reformed gas and an oxidizing gas, the reformed gas, and the oxidizing gas. A fuel cell system comprising a gas pipe for supplying a gas, wherein a motor-driven valve is provided on the gas pipe. 2. The fuel cell system according to claim 1, wherein the motor-driven valve is provided on a gas pipe in which the pressure on the gas outlet side of the valve is higher than the pressure on the gas inlet side. 3. The fuel cell system according to claim 1, wherein the motor-driven valve is provided on an oxidizing gas line that sends the oxidizing gas compressed by a compressor to the reformer.