JPH09199149A - Gas feeding/discharging device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly guide the fuel gas and air to electrodes without developing excessive differential pressure by providing small-diameter valves in parallel with a case-fuel electrode equalizing valve and a case-air electrode equalizing valve respectively. SOLUTION: A case-fuel electrode equalizing small valve 4 smaller in diameter than a case-fuel electrode equalizing valve 3 is provided on a small-diameter piping 4P bypassing the case-fuel electrode equalizing valve 3 in this gas feeding/ discharging device for a fuel cell. A case-air fuel equalizing small valve 11 smaller in diameter than a case-air electrode equalizing valve 10 is provided on a small-diameter pipe 11P bypassing the case-air electrode equalizing valve 10. Four valves 3, 4, 10, 11 are opened, the differential pressure is suppressed by the low fluid resistance of the case-fuel electrode equalizing valve 3 and the case-air electrode equalizing valve 10, and the nitrogen pressure is boosted on a fuel electrode, an air electrode, and the case. The equalizing valves 3, 10 are closed and the equalizing small valves 4, 11 are opened, and the differential pressure is suppressed to suppress the nitrogen flow. Nitrogen can be switched to reaction gas without generating an excessive differential pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention starts the supply of fuel gas and air after the fuel gas is supplied to the fuel electrode and the pressure and pressure equalization operations of the fuel electrode, the air electrode, and the casing by nitrogen are performed. The present invention relates to a gas supply / discharge device for a fuel cell that performs nitrogen purging of a fuel electrode and an air electrode with nitrogen when power generation is stopped.

[0002]

2. Description of the Related Art For example, a fuel cell in which a fuel cell main body (stack) in which a plurality of unit cells including a matrix holding an electrolyte and a fuel electrode and an air electrode sandwiching the matrix are stacked in a cell housing It is mechanically weak against excessive pressure differences between the pole and air pole, between the housing and fuel pole, and between the housing and air pole. That is,
In response to an excessive pressure difference, the hydrogen-rich fuel gas directly reacts with air due to gas blow-through between the fuel electrode and the air electrode, or the cell characteristics are deteriorated even if the gas does not blow-through. Further, between the housing-fuel electrode and between the housing-air electrode, the gas seal structure between the fuel electrode and the air electrode and the housing is damaged, and nitrogen in the housing enters the fuel electrode or the air electrode, This may cause deterioration of cell characteristics, or fuel and air may leak into the housing, resulting in a dangerous state where fuel and air coexist. Therefore, in order to prevent the occurrence of these obstacles, the fuel cell main body (stack) is housed in the cell housing, and the pressure between the fuel electrode and the air electrode and the housing-fuel electrode are set on the basis of the pressure of nitrogen supplied into the housing. The pressure difference between the poles and between the housing and the air pole is always the prescribed pressure difference set value, for example ± 500 mm.
Measures have been taken to control the fuel gas pressure in the fuel electrode and the air pressure in the air electrode so as to maintain below H ₂ O.

By the way, before the fuel cell starts power generation, a pressure increasing operation is performed to increase the gas pressures of the fuel electrode, the air electrode, and the casing to specified values, and the fuel electrode is operated with a constant flow rate of gas. A differential pressure control operation that adjusts the differential pressure between the air electrodes, between the housing and the fuel electrode, and between the housing and the air electrode is required. However, it is generally difficult to use fuel gas, air, and nitrogen for the above two preliminary operations and to perform them in parallel with each other while keeping the differential pressure below the set value. Therefore, the above two preliminary operations are performed using nitrogen as an inert gas,
An operation method is adopted in which nitrogen is switched to fuel gas and air when the differential pressure control operation is completed. Further, at the end of the power generation operation, nitrogen purge is performed to replace the fuel gas and air in the electrode with nitrogen.

FIG. 10 is a piping system diagram showing a conventional gas supply / discharge device for a fuel cell. In the figure, a fuel cell (stack) 30 is housed in a cell casing (also simply referred to as a casing) 31, and a gas supply / discharge device is provided in a fuel gas supply pipe system to a fuel electrode to control a flow rate. Fuel flow control valve 1
And a fuel electrode differential pressure control valve 5 provided in the fuel gas discharge piping system from the fuel electrode to control the differential pressure of the fuel electrode, and an air flow rate provided in the air supply piping system to the air electrode to control the flow rate. A control valve 8, an air electrode differential pressure control valve 12 provided in an air discharge piping system from the air electrode to control a differential pressure of the air electrode, and a housing 3.
1. A nitrogen flow rate control valve 15 provided in a nitrogen supply pipe system for controlling the flow rate, a case pressure control valve 16 provided in a nitrogen discharge pipe system from the case for controlling the pressure of the case, and a nitrogen The fuel electrode nitrogen supply valve 2 for controlling the supply of nitrogen to the fuel electrode, which is provided in the piping system communicating with the upstream side of the flow rate control valve 15 and the downstream side of the fuel flow rate control valve 1, and the nitrogen flow rate control valve 15. An air electrode nitrogen supply valve 9 that is provided in a piping system that communicates with the upstream side and the downstream side of the air flow rate control valve 8 and controls the supply of nitrogen to the air electrode, and the downstream side of the nitrogen flow rate control valve 15 and the fuel flow rate. A casing-fuel electrode pressure equalizing valve 3, which is provided in a piping system that communicates with the downstream side of the control valve 1 and suppresses a pressure difference between the fuel electrode and the casing.
A casing-air electrode equalizing valve 10 that is provided in a piping system that communicates with the downstream side of the nitrogen flow rate control valve 15 and the downstream side of the air flow rate control valve 8 to suppress the differential pressure between the air electrode and the casing; A fuel-atmosphere release differential pressure control valve 6 that is provided in a piping system that branches on the upstream side of the polar differential pressure control valve 5 and communicates with the atmosphere, and that adjusts the differential pressure between the atmospheric pressure and the fuel electrode, and the air polar differential pressure control valve. An air-atmosphere release differential pressure control valve 13 that is provided in a piping system that branches on the upstream side of 12 and communicates with the atmosphere and that adjusts the differential pressure between the atmosphere and the air electrode is provided.

In the conventional example, the casing-fuel electrode pressure equalizing valve 3
The casing-air electrode pressure equalizing valve 10 is a shutoff valve that is fully closed by a drive source such as a control air source and a control power source, and is fully opened by the loss of the drive source. An opening is controlled by a control source such as a control air source and a control power source, and a regulating valve that is in a fully closed state due to loss of a drive source is used.

Next, the valve operation of the conventional gas supply / exhaust device at the time of starting power generation of the fuel cell 30 and at the time of power generation stop will be described. (B) Pressurization operation of the fuel electrode, air electrode, and housing with nitrogen. When the openings of the nitrogen flow rate control valve 15 and the case pressure control valve 16 are controlled from the state where the drive source is lost and nitrogen is introduced into the case 31, the case in the fully open state-the fuel electrode pressure equalizing valve 3 and the case- Nitrogen is introduced into the fuel electrode and the air electrode through the air electrode pressure equalizing valve 10, and the pressures of the three are raised to the same pressure. If the fluid resistance of the casing-fuel electrode pressure equalizing valve 3 and the casing-air electrode pressure equalizing valve 10 and its piping is high due to this boosting operation, a transient differential pressure is likely to occur. And housing −
The caliber of the air electrode pressure equalizing valve 10 and its piping is set to, for example, the same caliber as that of the fuel supply piping system including the fuel flow control valve 1 and the air supply piping system including the air flow control valve 8.

(B) Differential pressure control operation of the fuel electrode, the air electrode, and the casing by nitrogen. The opening degrees of the fuel electrode nitrogen supply valve 2, the air electrode nitrogen supply valve 9, the fuel-atmosphere release differential pressure control valve 6 and the air-atmosphere release differential pressure control valve 13 are adjusted so that the fuel electrode-air electrode, the housing- A constant flow rate of nitrogen is passed through the fuel electrode and the air electrode while controlling the pressure difference between the fuel electrode and between the housing and the air electrode to be ± 500 mmH ₂ O or less.

(C) Switching operation from nitrogen to reaction gas. First, the casing-fuel electrode pressure equalizing valve 3 and the casing-air electrode pressure equalizing valve 10 are closed, and the opening degrees of the fuel flow rate control valve 1 and the air flow rate control valve 8 are adjusted to supply fuel gas to the fuel electrode and air to the air electrode. While gradually introducing, the fuel electrode nitrogen supply valve 2 and the air electrode nitrogen supply valve 9 are closed, and then the opening degrees of the fuel-atmosphere release differential pressure control valve 6 and the air-atmosphere release differential pressure control valve 13 are adjusted, Based on the body pressure, the pressure differences between the housing and the fuel electrode and between the housing and the air electrode are controlled to their set values (the fuel cell 30 is connected to the load circuit in this state).

(D) Switching operation to the power generation operation state The opening degree of the fuel electrode differential pressure control valve 5 and the air electrode differential pressure control valve 12 is gradually increased, and conversely, the fuel-atmosphere release differential pressure control valve 6 and the air- The opening of the atmospheric pressure release differential pressure control valve 13 is gradually reduced to transfer the flow of the reaction gas to the fuel electrode differential pressure control valve 5 and the air electrode differential pressure control valve 12. After that, the opening degree of the fuel flow rate control valve 1 and the air flow rate control valve 8 is controlled by an external command corresponding to the electric power value required by the load, and the differential pressure is set to a preset differential pressure value based on the casing pressure. Based on this, the opening degrees of the fuel electrode differential pressure control valve 5 and the air electrode differential pressure control valve 12 are automatically adjusted, and the pressures and differential pressures of the fuel electrode and the air electrode are adjusted to specified values. At this time, the openings of the nitrogen flow control valve 15 and the case pressure control valve 16 are automatically adjusted so that the case pressure is maintained at a set value and a small amount of nitrogen is discharged to the outside.

(E) Switching operation to the operation stop state. When the fuel electrode nitrogen supply valve 2 and the air flow rate control valve 8 are gradually closed, and the housing-fuel electrode pressure equalizing valve 3 and housing-air electrode pressure equalizing valve 10 are opened instead, nitrogen in the housing 31 becomes the housing- The fuel gas and air in the fuel electrode and the air electrode are supplied to the fuel electrode and the air electrode through the fuel electrode pressure equalizing valve 3 and the casing-air electrode pressure equalizing valve 10, and the fuel electrode differential pressure control valve 5 and the air electrode differential pressure are supplied. By being discharged through the control valve 12, the pressure difference between the fuel electrode and the air electrode, between the housing and the fuel electrode, and between the housing and the air electrode is suppressed to ± 500 mmH ₂ O or less, and the fuel gas and the air are nitrogen. A nitrogen purge to replace

[0011]

In the conventional gas supply and discharge device, the housing-fuel electrode pressure equalizing valve 3 and the housing-air electrode pressure equalizing valve 1 are used.
No. 0 and its pipe diameter are increased to the same diameter as that of the reaction gas supply piping system including the normal fuel flow rate control valve 1 and the air flow rate control valve 8 to reduce the fluid resistance. By increasing the pressure of the fuel electrode, the air electrode, and the housing with nitrogen, the differential pressure between the fuel electrode and the air electrode, between the housing and the fuel electrode, and between the housing and the air electrode is, for example, ± 500 mmH ₂ O or less. It is possible to raise the pressure of the fuel electrode, air electrode, and housing to the specified operating pressure value with the pressure kept to a minimum.

FIG. 11 is a diagram schematically showing a differential pressure control operation state of the fuel electrode, the air electrode, and the casing by nitrogen in the conventional example. The fuel electrode nitrogen supply valve 2, the air electrode nitrogen supply valve 9 and the fuel are shown. -Atmosphere release differential pressure control valve 6 and air-Adjusting the opening degree of the atmospheric release differential pressure control valve 13 to cause a constant flow rate of nitrogen to flow to the fuel electrode and the air electrode, the casing having low fluid resistance-Fuel electrode Pressure equalizing valve 3 and casing-air electrode pressure equalizing valve 10
A large amount of nitrogen flows into the casing 31 having a lower fluid resistance than the fuel electrode and the air electrode through the fuel cell, and the flow rate of the fuel gas and the air to the fuel electrode and the air electrode is reduced by that much. Therefore, the differential pressure control by the fuel-atmosphere release differential pressure control valve 6 and the air-atmosphere release differential pressure control valve 13 becomes unstable, sometimes due to pressure fluctuation (hunting phenomenon) between the fuel electrode-air electrode and the case-fuel electrode. There is a problem that an excessive differential pressure is generated between the fuel cell and the housing and the air electrode, and the fuel cell is damaged. Further, when shifting to the switching operation from nitrogen to the reaction gas described in (C), the fuel electrode nitrogen supply valve 2 and the air electrode nitrogen supply valve 9 are throttled to make the fuel flow rate control valve 1 and the fuel electrode differential pressure control valve. In the process of gradually introducing the fuel gas to the fuel electrode and the air to the air electrode by adjusting the opening degree of 5,
Since the pressure on the fuel electrode side and the pressure on the air electrode side transiently drop below the pressure on the housing side, the nitrogen supplied to the housing passes through the housing-fuel electrode pressure equalizing valve 3 and the housing-air electrode pressure equalizing valve 10. Although it will be released to the fuel electrode side and the air electrode side, and the situation where fuel gas or air enters the casing can be avoided, the casing-fuel electrode pressure equalizing valve 3 and the casing-air electrode pressure equalizing valve 10 are closed. In the process, an excessive differential pressure is generated due to the hunting phenomenon and the fuel cell is damaged.

On the other hand, when a power failure or the like occurs, the control power source of the fuel cell power generator which is the drive source of the valve is lost, or the control air compressor is stopped and the control air for the valve opening is lost. . For this reason, it is not possible to perform a sequential stop operation of the gas supply / discharge device (for example, a nitrogen purge or a pressure reduction operation of the fuel electrode, the air electrode, and the casing to the atmospheric pressure). As a countermeasure, it is possible to install an uninterruptible power supply (CVCF), but in order to avoid the increase in size of equipment and the rise in equipment costs, normally, a pressure equalizing valve that opens when the drive source is lost is used. Measures are taken to suppress the rise in pressure.

FIG. 12 is a diagram schematically showing the valve position when the drive source is lost in the conventional example. The case-fuel electrode pressure equalizing valve 3 and the case-air electrode pressure equalizing valve 10 are air pressure, electricity, etc. When the drive source of is lost, it will be in the fully open state, but the other valves will be in the fully closed state due to the loss of the drive source such as air pressure and electricity, and the fuel electrode, the air electrode, and the casing will each have a constant pressure of fuel gas, It encloses air and nitrogen, and is in a stopped state in a state where they are in communication with each other by the casing-fuel electrode pressure equalizing valve 3 and casing-air electrode pressure equalizing valve 10 in the open state. Therefore,
There is a problem that an unsafe stop state in which the fuel gas and the air are mixed and directly react with each other inside the fuel cell is caused.

An object of the present invention is to supply gas to a fuel cell which can start the supply of fuel gas and air without producing an excessive differential pressure and can stably perform nitrogen purging at the end of power generation and when the drive source is lost. To provide an ejector.

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 supplies nitrogen to the battery casing.
A device for discharging and supplying and discharging fuel gas to the fuel electrode and air to the air electrode of the fuel cell housed in the cell housing, which is provided in the fuel gas supply piping system and controls the flow rate. A flow control valve, a fuel electrode differential pressure control valve installed in the fuel gas exhaust piping system to control the differential pressure of the fuel electrode, an air flow control valve installed in the air supply piping system to control the flow rate, and an air exhaust An air electrode differential pressure control valve installed in the piping system to control the differential pressure of the air electrode, a nitrogen flow control valve installed in the nitrogen supply piping system to control the flow rate, and a housing installed in the nitrogen discharge piping system. And a fuel for controlling the supply of nitrogen to the fuel electrode, which is provided in a pipe system that communicates with a casing pressure control valve that controls the pressure of the fuel cell and an upstream side of the nitrogen flow rate control valve and a downstream side of the fuel flow rate control valve. Polar nitrogen supply valve, upstream of the nitrogen flow control valve and the air flow An air electrode nitrogen supply valve that is provided in a piping system that communicates with the downstream side of the control valve and controls the supply of nitrogen to the air electrode, a downstream side of the nitrogen flow rate control valve and a downstream side of the fuel flow rate control valve. A casing provided in a pipe system communicating with the casing for suppressing a pressure difference between the fuel electrode and the casing-a fuel electrode pressure equalizing valve, and communicated with a downstream side of the nitrogen flow rate control valve and a downstream side of the air flow rate control valve. Provided in the piping system for suppressing the pressure difference between the air electrode and the housing-the air electrode pressure equalizing valve, and provided in the piping system branching upstream of the fuel electrode differential pressure control valve and communicating with the atmosphere. A fuel-atmosphere release differential pressure control valve for adjusting the differential pressure between the atmosphere and the fuel electrode, and a pipe system branching upstream of the air electrode differential pressure control valve and communicating with the atmosphere. The air-atmosphere release differential pressure control valve for adjusting the differential pressure of the In a gas supply / discharge device for performing pressure increasing operation and pressure equalizing operation of a fuel electrode, an air electrode, and a casing by means of a casing-fuel electrode equalizing valve provided in a pipe of a small diameter bypassing the casing-fuel electrode equalizing valve. Small-diameter casing-fuel electrode equalizing small valve, and casing provided in a small-diameter pipe that bypasses the casing-air electrode equalizing valve-smaller diameter casing than the air electrode equalizing valve-air electrode equalizing valve With a small valve.

The invention described in claim 2 is the gas supply / discharge device for a fuel cell according to claim 1, wherein
Both the fuel electrode pressure equalizing valve, the housing-fuel electrode pressure equalizing small valve, the housing-air electrode pressure equalizing valve, and the housing-air electrode pressure equalizing small valve are opened by the action of the spring when their drive sources are lost. A shutoff valve is preferred. Further, the invention according to claim 3 is
The gas supply / discharge device for a fuel cell according to claim 1 or 2, wherein a pipe system that bypasses the fuel-atmosphere release differential pressure control valve, and a fuel-atmosphere release valve provided in this pipe system, and air- A piping system that bypasses the atmospheric release differential pressure control valve,
And an air-atmosphere release valve provided in this piping system,
It is preferable that both the fuel-atmosphere discharge valve and the air-atmosphere discharge valve are cut-off valves that are opened by the action of a spring when their drive sources are lost.

Further, the invention according to claim 4 is the gas supply / exhaust device for a fuel cell according to claim 3, wherein:
The atmosphere release valve and the air-air atmosphere release valve may each be provided with an orifice connected in series. On the other hand, the invention according to claim 5 is the gas supply / discharge device for a fuel cell according to claim 1, wherein a fuel flow rate control valve, a fuel pole differential pressure control valve, an air flow rate control valve, and an air pole differential pressure control valve are provided. , A nitrogen flow control valve, a housing pressure control valve, a fuel electrode nitrogen supply valve, an air electrode nitrogen supply valve, a fuel-atmosphere release differential pressure control valve, and an air-atmosphere release differential pressure control valve are both control air sources and controls. It is preferable that the flow control valve is configured to adjust the opening degree by a control source such as a power source, and the shutoff valve is closed in the state where the control source is lost and is closed in series in the state where the control source is lost.

According to the first aspect of the invention, in the boosting operation of the fuel electrode, the air electrode, and the casing by nitrogen described in (a), the casing-fuel electrode equalizing valve and the casing-fuel electrode equalizing small pressure. By opening the valve, housing-cathode equalizing valve and housing-cathode equalizing small valve, the differential pressure is suppressed by the low fluid resistance of the housing-fuel electrode equalizing valve and the housing-cathode equalizing valve. In this state, it is possible to boost the nitrogen pressure of the fuel electrode, air electrode, and housing. Further, in the differential pressure control operation of the fuel electrode, the air electrode, and the housing by nitrogen described in (b), the housing-fuel electrode pressure equalizing valve and the housing-air electrode pressure equalizing valve are closed, and the housing having high fluid resistance is closed. By opening the body-fuel electrode pressure equalizing small valve and the casing-air electrode pressure equalizing small valve to suppress the differential pressure, the flow rate of nitrogen flowing into the cell casing via the pressure equalizing small valve is suppressed. Further, in the switching operation from the nitrogen to the reaction gas described in (C), the flow rate of nitrogen flowing back to the fuel electrode and the air electrode via the pressure equalizing small valve is suppressed. The resulting hunting phenomenon is also suppressed, and the operation of switching from nitrogen to the reaction gas is performed without generating an excessive differential pressure.

According to a second aspect of the invention, in the gas supply / discharge device for the fuel cell according to the first aspect, the casing-fuel electrode pressure equalizing valve, the casing-fuel electrode pressure equalizing small valve, the casing-air. Pole equalization valve,
Since both the casing and the air electrode pressure equalizing small valve are shut off valves that are opened by the action of the spring when the drive source is lost, even if other valves are closed due to the loss of the drive source, the fuel electrode, The air electrode and the housing communicate with each other to prevent the generation of differential pressure.

According to the third aspect of the invention, the fuel-atmosphere release valve and the air-atmosphere release valve provided in parallel with the fuel-atmosphere release differential pressure control valve and the air-atmosphere release differential pressure control valve have a drive source loss. At the same time, it is opened by the action of the spring, and the complementary action with claim 2 forms a nitrogen purge path for releasing the fuel gas in the fuel electrode and the air in the air electrode to the atmosphere by utilizing the pressure of nitrogen in the housing. .

According to the fourth aspect of the present invention, when the fuel-air release valve and the air-air release valve are opened when the drive source is lost, the orifice suppresses the flow rate of gas released into the atmosphere. The generated differential pressure is suppressed, nitrogen purge is performed without generating an excessive differential pressure, and the fuel electrode,
The air electrode and the casing are slowly introduced into the nitrogen atmosphere at atmospheric pressure.

In the invention described in claim 5, the disadvantage of the shutoff property of the flow rate adjusting valve whose opening is adjusted by a control source such as electricity is taken advantage of by the excellent shutoff property of the shutoff valve provided in series therewith. Since this can be complemented, inconveniences such as, for example, continuing supply of a small amount of fuel gas even after the nitrogen purge is eliminated, the nitrogen purge becomes more reliable when the control source is lost, and the safety of the fuel cell is maintained.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Since the members having the same reference numerals as those of the conventional example have the same functions as those of the conventional example, the description thereof will be omitted. FIG. 1 is a piping system diagram showing a gas supply / discharge device for a fuel cell according to an embodiment of the present invention. In the figure, the gas supply / exhaust device of this embodiment differs from the conventional gas supply / exhaust device shown in FIG. 10 in that the housing-the housing provided in a small-diameter pipe 4P that bypasses the fuel electrode pressure equalizing valve 3-the fuel Case-smaller diameter than the pole-equal pressure equalizing valve 3 and housing-smaller-diameter pipe 11P bypassing the case-air pole equalizing-valve 10 and the case-air pole equalizing-valve 10. The case-the air electrode pressure equalizing small valve 11 is provided.

The housing-fuel electrode pressure equalizing small valve 4 and the housing-air electrode pressure equalizing small valve 11 have the same electrical characteristics as the case-fuel electrode pressure equalizing valve 3 and housing-air electrode pressure equalizing valve 10. A shut-off valve that is opened by the action of a spring when the drive source such as gas pressure is lost is used. FIG. 2 is a view schematically showing the fuel electrode, the air electrode, and the valve position in the pressure rising operation of the casing of the embodiment shown in FIG. 1, and the casing-fuel electrode pressure equalizing valve 3, the casing-fuel electrode. Pressure equalizing small valve 4, casing-air electrode pressure equalizing valve 10
When the openings of the nitrogen flow control valve 15 and the housing pressure control valve 16 are adjusted with the housing-air electrode equalizing small valve 11 open and the other valves closed, nitrogen flows into the housing 31 at the same time. , Casing with low fluid resistance-Fuel electrode equalizing valve 3 and casing-
Nitrogen flows into the fuel electrode and the air electrode through the air electrode pressure equalizing valve 10, and suppresses the differential pressure between the fuel electrode and the air electrode, between the housing and the fuel electrode, and between the housing and the air electrode to the differential pressure set value or less. In this state, the fuel electrode, the air electrode, and the housing are pressurized to the specified pressure.

FIG. 3 is a diagram schematically showing the valve positions in the differential pressure control operation of the fuel electrode, the air electrode, and the casing by nitrogen in the embodiment shown in FIG. 1. First, the casing-fuel electrode pressure equalizing valve 3
And the housing-air electrode pressure equalizing valve 10 is closed, the fuel electrode nitrogen supply valve 2 and the air electrode nitrogen supply valve 9 are gradually opened to supply nitrogen to the fuel electrode and the air electrode, and the fuel-atmosphere release differential pressure control valve. 6 and the opening degree of the air-atmosphere release differential pressure control valve 13 are adjusted to control the differential pressure between the housing-fuel electrode and between the housing-air electrode to the differential pressure set value. At this time, the open casing-fuel electrode pressure equalizing small valve 4 and the casing-air electrode pressure equalizing small valve 11 absorb pressure fluctuations and suppress the generation of excessive differential pressure.
For example, when the diameters of the housing-fuel electrode pressure equalizing valve 3 and the housing-air electrode pressure equalizing valve 10 are 100A, the diameters of the housing-fuel electrode pressure equalizing small valve 4 and the housing-air electrode pressure equalizing small valve 11 are set. By setting the flow path resistance to a high value by reducing it to about 25 A, the flow of nitrogen into the battery case 31 is suppressed.

FIG. 4 is a diagram schematically showing the valve position in the switching operation from the nitrogen gas to the reaction gas in the embodiment shown in FIG. 1. First, the case-fuel electrode pressure equalizing small valve 4 and the case-air electrode. The pressure equalizing small valve 11 is closed. At this time, the flow rate of nitrogen to the battery case is suppressed to be much smaller than the conventional one due to the high flow resistance of the case-fuel electrode pressure equalizing small valve 4 and the case-air electrode pressure equalizing small valve 11, so that hunting is performed. The phenomenon is small,
Therefore, generation of an excessive pressure difference is also prevented. Then, the fuel flow rate control valve 1 and the air flow rate control valve 8 are gradually opened to start the supply of the fuel gas and the air, and the fuel electrode nitrogen supply valve 2 and the air electrode nitrogen supply valve 9 are gradually throttled and fully closed. . By such operation, fuel electrode, air electrode,
Fuel gas, air, and nitrogen are supplied to the battery case and the cell case, respectively, and the pressure difference between the fuel electrode and the air electrode is controlled to be constant based on the case pressure controlled to a constant pressure.

FIG. 5 is a diagram schematically showing the valve positions in the switching operation to the power generation operation state of the embodiment shown in FIG. 1, and the opening degrees of the fuel electrode differential pressure control valve 5 and the air electrode differential pressure control valve 12. Is gradually increased, and conversely, the opening degrees of the fuel-atmosphere release differential pressure control valve 6 and the air-atmosphere release differential pressure control valve 13 are gradually reduced so that the flow of the reaction gas is controlled by the fuel pole differential pressure control valve 5 and the air pole difference. The power generation operation can be performed by transferring the pressure control valve 12.

FIG. 6 is a piping system diagram showing a gas supply / discharge device for a fuel cell according to a different embodiment of the present invention. This embodiment differs from the embodiment shown in FIG. 1 in that a fuel-atmosphere release differential pressure control valve 13 and a fuel-atmosphere release differential pressure control valve 13 provided in a piping system 7P bypassing the fuel-atmosphere release differential pressure control valve 6 are provided. Air-atmosphere release valve 14 provided in the piping system 14P that bypasses the
And a shutoff valve that is opened by the action of a spring when the drive source is lost for the fuel-atmosphere release valve 7 and the air-atmosphere release valve 14.

FIG. 7 is a diagram schematically showing the valve position when the drive source of the embodiment shown in FIG. 6 is lost. Due to the loss of the drive source such as air pressure and electricity, each flow rate control valve 1, 2, 5, 5 is shown.
6,8,9,12,13,15,16 are fully closed, and fuel gas is filled in the fuel electrode, air is filled in the air electrode, and nitrogen is filled in the battery case. Shut-off valve 3, 4, which is opened by the action of the spring when the source is lost
6, 7, 10, 11, and 14 are fully opened, and nitrogen in the cell housing is supplied to the fuel electrode through the housing-fuel electrode pressure equalizing valve 3 and the housing-fuel electrode pressure equalizing small valve 4, and the fuel electrode A nitrogen purge path for releasing the fuel gas in the interior to the atmosphere via the fuel-atmosphere release valve 7, and the nitrogen in the battery enclosure for the enclosure-air electrode pressure equalizing valve 10,
A nitrogen purge path for supplying air to the air electrode through the casing-air electrode pressure equalizing small valve 11 and discharging the air in the air electrode into the atmosphere through the air-atmosphere discharge valve 14 is formed. The air electrode is replaced with nitrogen at atmospheric pressure. In addition, fuel electrode, air electrode,
And the battery case has a low flow passage resistance-the fuel electrode pressure equalizing valve 3, the case-air electrode pressure equalizing valve 10, and the case-fuel electrode pressure equalizing small valve 4, the case-air electrode pressure equalizing small valve 11. As a result, they are brought into communication with each other, so that the pressure differences between the housing and the fuel electrode, between the housing and the air electrode, and between the fuel electrode and the air electrode are suppressed.

FIG. 8 is a piping system diagram showing in schematic valve position a main part of a gas supply / discharge device for a fuel cell according to another embodiment of the present invention. This embodiment differs from the other embodiments in that the fuel-air release valve 7 and the air-air release valve 14 each have an orifice 21 connected in series. Fuel-Atmosphere Release Valve 7 and Air-Atmosphere Release Valve 1
4, the upstream side is the operating pressure of the battery, the downstream side is the atmospheric pressure, and the differential pressure is large. Therefore, in a power generator in which the operating pressure of the battery is set high, for example, the release valves 7 and 14 are shut off with a small diameter of about 25 A. Even if the valve is used, a large amount of gas may flow out when the control power source or the air source is lost, and an excessive pressure difference may occur between the housing and the fuel electrode and between the housing and the air electrode.
If, as in this embodiment, the restriction orifice 21 having a small diameter is formed by using, for example, the mounting flanges of the fuel-atmosphere release valve 7 and the air-atmosphere release valve 14 and the like, the discharged gas can be obtained without increasing the size of the apparatus. This has the advantage that the flow rate is limited and the nitrogen purge is performed gently, and the inside of the fuel electrode, the inside of the air electrode, and the inside of the housing can be introduced into a nitrogen atmosphere at atmospheric pressure.

FIG. 9 is a schematic piping system diagram showing valve positions of a gas supply / discharge device for a fuel cell according to another embodiment of the present invention. This embodiment is different from the embodiment shown in FIG. 6 in that the flow rate control valves 1, 2, 5, 6, 8, 9, 12, 13, 15, 16 which are closed when the drive source is lost are connected in series. , Shut-off valve 20 that opens when the drive source is lost
Since the flow control valve is somewhat inferior in shutoff property, it is supplemented by utilizing the excellent shutoff property of the shutoff valve 20 provided in series, and even after the nitrogen purge, a small amount of fuel gas or The advantage is that it is possible to reliably avoid an unsafe state in which air is supplied to the fuel electrode and the air electrode and is continuously discharged.

[0033]

As described above, the gas supply / discharge device for a fuel cell according to the present invention has a large-diameter casing-a fuel electrode equalizing valve and a casing-a small-diameter casing in parallel with each of the air electrode equalizing valves- A fuel electrode pressure equalizing small valve and a housing-air electrode pressure equalizing small valve were provided. As a result, when boosting operation of the fuel electrode, air electrode, and housing with nitrogen, the differential pressure is suppressed by using the low flow resistance of the large diameter housing-fuel electrode pressure equalizing valve and housing-air electrode pressure equalizing valve. When operating the differential pressure control of the fuel electrode, the air electrode, and the housing by nitrogen, the housing-the fuel electrode pressure equalizing small valve and the housing-
The high flow resistance of the air electrode pressure equalizing small valve is used to prevent excessive inflow of nitrogen into the battery case, and during the switching operation from nitrogen to reaction gas, the case-fuel electrode pressure equalizing small valve and the housing Body
The pressure fluctuation between the housing and the fuel electrode and the increase in the pressure difference between the housing and the air electrode, which are caused by the shutoff of the air electrode pressure equalizing small valve, and the increase in the differential pressure are suppressed, which is a problem in the conventional example. A fuel cell equipped with a gas supply / exhaust device capable of avoiding damage to the fuel cell due to an excessive pressure difference occurring at the start of power generation of the fuel cell and smoothly introducing fuel gas and air into the electrode without causing an excessive pressure difference Can be provided.

Further, in parallel with the fuel-atmosphere release differential pressure control valve and the air-atmosphere release differential pressure control valve, respectively, the fuel-atmosphere release valve and the air-atmosphere are opened by the action of the spring when the drive source is lost. A discharge valve was provided.
As a result, when the drive power source, the control air source, etc. are lost due to a power failure or the like, the fuel-atmosphere release valve and the air-atmosphere release valve are opened, and likewise, the casing is open. The body-fuel electrode pressure equalizing valve, the case-air electrode pressure equalizing valve, the case-fuel electrode pressure equalizing small valve, and the case-air electrode pressure equalizing small valve complement the nitrogen in the cell case to the fuel electrode. A nitrogen purge path for discharging to the atmosphere via the air electrode and the air electrode will be formed, and the pressurized fuel gas and air will be sealed in the fuel electrode and the air electrode that are in communication by the pressure equalizing valve. The unsafe condition of the conventional technology that
Nitrogen purging is automatically performed not only when the operation is stopped steadily but also when the drive source is lost in an untimely manner, and the fuel electrode, air electrode, and the atmosphere are introduced into a nitrogen atmosphere at atmospheric pressure to ensure a safe state. It is possible to provide a fuel cell provided with a highly reliable gas supply and discharge device. Further, since it is not necessary to install an uninterruptible power supply, which was conventionally required for ensuring safety, there is an advantage that it can contribute to reduction of equipment cost and downsizing of a power generator.

[Brief description of drawings]

FIG. 1 is a piping system diagram showing a gas supply / discharge device for a fuel cell according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing a valve position in a pressure increasing operation of a fuel electrode, an air electrode, and a casing by nitrogen in the embodiment shown in FIG.

FIG. 3 is a diagram schematically showing a valve position in a differential pressure control operation of a fuel electrode, an air electrode, and a casing by nitrogen in the embodiment shown in FIG.

FIG. 4 is a diagram schematically showing a valve position in a switching operation from nitrogen to a reaction gas in the embodiment shown in FIG.

FIG. 5 is a diagram schematically showing a valve position in a switching operation to a power generation operation state of the embodiment shown in FIG.

FIG. 6 is a piping system diagram showing a gas supply / discharge device for a fuel cell according to a different embodiment of the present invention.

FIG. 7 is a diagram schematically showing a valve position when the drive source is lost in the embodiment shown in FIG.

FIG. 8 is a piping system diagram showing in schematic valve position the essential parts of a gas supply / discharge device for a fuel cell according to another embodiment of the present invention.

FIG. 9 is a piping system diagram showing the gas supply / exhaust device for a fuel cell according to another embodiment of the present invention, the valve position being schematically shown.

FIG. 10 is a piping system diagram showing a conventional gas supply / discharge device for a fuel cell.

FIG. 11 shows a fuel electrode, an air electrode by nitrogen in a conventional example,
And a diagram schematically showing the differential pressure control operation state of the housing

FIG. 12 is a diagram schematically showing a valve position when a drive source is lost in a conventional example.

[Explanation of symbols]

 1 Fuel flow rate control valve 2 Fuel electrode nitrogen supply valve 3 Case-Fuel electrode pressure equalizing valve 4 Case-Fuel electrode pressure equalizing small valve 5 Fuel electrode differential pressure control valve 6 Fuel-atmosphere release Differential pressure control valve 7 Fuel-atmosphere release Valve 8 Air flow rate control valve 9 Air electrode nitrogen supply valve 10 Case-air electrode pressure equalizing valve 11 Case-air electrode pressure equalizing small valve 12 Air electrode differential pressure control valve 13 Air-atmosphere release differential pressure control valve 14 Air-atmosphere Release valve 15 Nitrogen flow rate control valve 16 Case pressure control valve 20 Shutoff valve 21 Orifice 30 Fuel cell 31 Battery case

Claims (5)

[Claims] 1. A device for supplying / discharging nitrogen to / from a cell casing, supplying / discharging fuel gas to / from a fuel electrode and air to / from an air electrode of a fuel cell housed in the cell casing, respectively. A fuel flow rate control valve provided in the gas supply piping system to control the flow rate, a fuel electrode differential pressure control valve provided in the fuel gas discharge piping system to control the differential pressure of the fuel electrode, and an air supply piping system Flow rate control valve to control the flow rate, an air electrode differential pressure control valve to control the differential pressure of the air electrode provided in the air exhaust piping system, and a nitrogen flow rate control valve to control the flow rate in the nitrogen supply piping system A valve, a casing pressure control valve provided in the nitrogen discharge piping system to control the pressure of the casing, and a piping system communicating with the upstream side of the nitrogen flow control valve and the downstream side of the fuel flow control valve. And a fuel electrode nitrogen supply valve for controlling the supply of nitrogen to the fuel electrode. An air electrode nitrogen supply valve that is provided in a piping system that communicates with the upstream side of the elementary flow rate control valve and the downstream side of the air flow rate control valve and controls the supply of nitrogen to the air electrode, and the downstream side of the nitrogen flow rate control valve. Side and a downstream side of the fuel flow rate control valve, which is provided in a piping system that suppresses the differential pressure between the fuel electrode and the case-a fuel electrode pressure equalizing valve, and a downstream side of the nitrogen flow rate control valve. A casing provided in a piping system communicating with the downstream side of the air flow rate control valve to suppress the differential pressure between the air electrode and the casing-an air electrode pressure equalizing valve, and an upstream side of the fuel electrode differential pressure control valve. A fuel-atmosphere release differential pressure control valve that is provided in a pipe system that branches and communicates with the atmosphere and that regulates the differential pressure between the atmosphere and the fuel electrode, and a branch on the upstream side of the air electrode differential pressure control valve that communicates with the atmosphere. The air-atmosphere release differential pressure control valve for adjusting the differential pressure between the atmosphere and the air electrode, the fuel gas And the air fuel electrode by nitrogen prior to the start of the supply of the gas supply and discharge apparatus for performing the boost operation and equalizing pressure operation of the air electrode and the housing,
The casing-a casing provided in a small-diameter pipe that bypasses the fuel electrode pressure equalizing valve-a casing having a smaller diameter than the fuel electrode pressure equalizing valve-a fuel electrode pressure equalizing small valve, and the casing-bypassing the air electrode pressure equalizing valve A gas supply / discharge device for a fuel cell, comprising: a casing provided in a pipe having a small diameter, a casing having a smaller diameter than the air electrode pressure equalizing valve, and an air electrode pressure equalizing small valve. 2. The gas supply / discharge device for a fuel cell according to claim 1, wherein the housing-fuel electrode pressure equalizing valve, the housing-fuel electrode pressure equalizing small valve, the housing-air electrode equalizing valve, and the housing. A gas supply / discharge device for a fuel cell, characterized in that both the air electrode pressure equalizing small valves are shut-off valves that are opened by the action of a spring when their drive source is lost. 3. The gas supply / discharge device for a fuel cell according to claim 1 or 2, wherein a pipe system bypassing the fuel-atmosphere release differential pressure control valve, and a fuel-atmosphere release provided in this pipe system. Valve, a piping system that bypasses the air-atmosphere release differential pressure control valve, and an air-atmosphere release valve provided in this piping system, and the fuel-atmosphere release valve and the air-atmosphere release valve are both driving sources thereof. A gas supply / exhaust device for a fuel cell, which is a shutoff valve that is opened by the action of a spring when the fuel is lost. 4. The gas supply / discharge device for a fuel cell according to claim 3, wherein the fuel-atmosphere release valve and the air-atmosphere release valve each have an orifice connected in series. Gas supply / discharge device for batteries. 5. The gas supply / discharge device for a fuel cell according to claim 1, wherein a fuel flow rate control valve, a fuel pole differential pressure control valve, an air flow rate control valve, an air pole differential pressure control valve, a nitrogen flow rate control valve, The casing pressure control valve, the fuel electrode nitrogen supply valve, the air electrode nitrogen supply valve, the fuel-atmosphere release differential pressure control valve, and the air-atmosphere release differential pressure control valve are all control sources such as a control air source and a control power source. A gas for a fuel cell, which comprises a flow control valve whose opening degree is adjusted by, and which is provided with a shut-off valve which is closed in a state where the control source is lost and is closed in series in a state where the control source is lost. Supply and discharge device.