JPH07272739A - Fuel cell purge device - Google Patents

Abstract

PURPOSE:To provide a device with no obstacle for protecting a catalyst, even when a power supply lost time is lengthened, by providing a fine flow valve or orifice in parallel to a primary pressure regulating valve in a cylinder collecting pipe in an inlet side of a pressure reducing valve. CONSTITUTION:A primary pressure adjusting valve 6 is interposed in a cylinder collecting pipe 2 in an inlet side of a pressure reducing valve 3, to provide a fine flow valve or orifice 7 in parallel to the valve 6. In a side of a fuel cell A, a current carrying closed type main solenoid valve 4 is interposed, to connect a catalyst protecting current carrying closed type fine flow solenoid valve 5 in parallel to the valve 4. In the case of use, the valve is left as adjusted to about one of several fractions a charging pressure of a setting pressure cylinder 1 of the valve 6. When a power supply of a control device D is lost, the valves 4, 5 are opened to release a large amount of nitrogen gas through the valve 3 from a cylinder unit B. When a cylinder pressure is decreased to a prescribed value or less, the valve 6 is closed, thereafter to supply a fine flow amount of nitrogen gas to the cell A through only the orifice 7. Accordingly, even without restoring the power supply for several tens of hours, catalyst protecting purge gas is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for purging (replacing) the combustible gas remaining inside when the operation of a fuel cell is stopped.

[0002]

2. Description of the Related Art A fuel cell is composed of a fuel reformer for converting natural gas into hydrogen, a cell stack for reacting hydrogen and oxygen to take out electricity, and it is safe to stop the operation. Therefore, it is necessary to purge the combustible gas inside, and also after purging the combustible gas, it is necessary to protect the catalyst with nitrogen gas so as not to damage the catalyst by contacting with oxygen or water vapor. FIG. 1 shows a conventional fuel cell purging device, which is a cylinder unit B in which a pressure reducing valve 3 is connected to a cylinder collecting pipe 2 to which a plurality of nitrogen cylinders 1 are connected.
Is connected to the fuel cell main body C via the energization-closed type main solenoid valve 4, and the energization-closed type minute flow rate solenoid valve 5 is connected in parallel with the main solenoid valve 4 to stop the operation. First, the main solenoid valve 4 with a large flow rate is opened, nitrogen gas is allowed to flow for a certain period of time to purge the combustible gas in the system, and then the valve 4 is closed.
After that, only the minute flow rate solenoid valve 5 for protecting the catalyst is used to continuously or intermittently flow the nitrogen gas during the operation stop period to protect the catalyst of the fuel reformer and the cell stack. The main solenoid valve 4 and the minute flow solenoid valve 5 are energized closed type in order to ensure safety by opening the solenoid valve and flowing purge gas at the time of power failure.

[0003]

However, in the above-mentioned structure, when the power source for controlling the fuel cell is lost due to a power failure or a failure, the solenoid valves 4 and 5 of the energized closed type are opened, so that the internal system is closed. The combustible gas is replaced with nitrogen gas to ensure safety, but if the power loss time is too long, the nitrogen gas accumulated in the cylinder will be exhausted, and the purging for catalyst protection will continue after that. become unable.
If the purge control of the cylinder unit B is to be performed during a power failure, for example, a battery type flow sensor, a timer, a valve, or the like is provided on the cylinder unit side, and a large amount of purge gas is released for a fixed time (for example, 10
However, in addition to the high cost, there is a problem in terms of reliability when considering that operation is rare. Therefore, there was a problem that the staff member had to rush to the site even at midnight and replace the nitrogen cylinder with a new one before the nitrogen cylinder became empty (for example, within 30 minutes after the power failure). SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a fuel cell purging device that does not hinder the protection of the catalyst even if the power loss time becomes long.

[0004]

According to the present invention, as shown in FIG. 2, a cylinder collecting pipe 2 in which a plurality of nitrogen cylinders 1 are connected.
A cylinder unit B having a pressure reducing valve 3 interposed therein is connected to a fuel cell main body C via an energized closed main solenoid valve 4 for purging combustible gas, and in parallel with the main solenoid valve 4, energization for catalyst protection is conducted. For a fuel cell in which a closed type small amount solenoid valve 5 is connected and the main solenoid valve is opened when the operation of the fuel cell is stopped to perform a combustible gas purge for a certain period of time and then only the minute flow solenoid valve is opened to protect the catalyst. In the purging device, a primary pressure adjusting valve 6 is provided in the cylinder collecting pipe 2 on the inlet side of the pressure reducing valve 3,
A minute flow rate valve or orifice 7 is provided in parallel with the primary pressure adjusting valve 6.

[0005]

According to the above construction, the set pressure of the primary pressure adjusting valve 6 should be adjusted to a value which is a fraction of the filling pressure (150 kg / cm 2 G) of the cylinder 1 (for example, 20 kg / cm 2 G). For example, even if a large amount of nitrogen is released due to power loss, the primary pressure regulating valve 6 is shut off leaving a sufficient amount of nitrogen gas for catalyst protection. A purge of nitrogen gas at a flow rate can be ensured, and therefore there is no risk of catalyst damage even if the power supply is lost for a long time.

[0006]

FIG. 2 shows an embodiment of the fuel cell purging device according to the present invention. A cylinder unit B is connected to a plurality of nitrogen gas cylinders 1 and a pressure reducing valve 3 is connected to a cylinder collecting pipe 2.
The pressure reducing valve 3 is used for normal filling 1
50kg / cm2 G cylinder pressure is 5-10kg / cm
Depressurized to 2 G and sent to fuel cell A. A primary pressure adjusting valve 6 is provided in the cylinder collecting pipe 2 on the inlet side of the pressure reducing valve 3, and a minute flow valve or orifice 7 is provided in parallel with the primary pressure adjusting valve 6, and the cylinder unit B is On the side of the fuel cell A to be connected, an energized closed type main solenoid valve 4 that closes the valve when energized is inserted in the connection port, and an energized closed type minute solenoid valve 5 for catalyst protection is connected in parallel with this main solenoid valve 4. Has been done. In the figure, 8 is a main flow rate adjusting valve, and 9 is a fine flow rate adjusting valve.

In use, the set pressure of the primary pressure control valve 6 is a value (20 to 30) which is a fraction of the filling pressure of the cylinder 1.
Adjust to kg / cm2 G). When the power supply of the control unit D is lost, the energization-closed main solenoid valve 4 and the minute flow solenoid valve 5 are opened, and a large amount of nitrogen from the cylinder unit B is generated at the secondary pressure of the pressure reducing valve 3 (for example, 6 kg / cm 2 G). It is released, but after 30 minutes, the cylinder pressure is 20 kg / cm 2 G
When the pressure drops below, the primary pressure regulating valve 6 detects it and closes it. Thereafter, a small flow rate of nitrogen gas is supplied to the fuel cell A at 6 kg / cm 2 G through only the orifice 7, and then the power is supplied for several tens of hours. Even if the gas does not recover, the purge gas for catalyst protection is maintained. In the figure, 10 is a pressure gauge and 11 is a safety valve.

FIG. 3 compares the operation of the conventional configuration (solid line) with the operation of the present invention (broken line).
Indicates the cylinder residual pressure, and (b) indicates the outflow amount from the cylinder. According to the conventional configuration of FIG. 1, when the power source is lost at t0, the solenoid valves 4 and 5 on the fuel cell side are opened, so that the purge gas is set by the main flow rate adjusting valve 8 as shown in (b). Flow at a flow rate for purging combustible gas, and even after the purging of combustible gas is completed at t1, since the main solenoid valve 5 is not controlled, the pressure reducing valve 3 maintains a constant pressure (for example, 6 kg / c).
m2 G) and keep flowing at almost the same flow rate.
Then, as shown in (a), the primary pressure is 6 at t3.
After becoming less than kg / cm 2 G, the flow rate becomes 0 after a while. On the other hand, in the configuration of the present invention shown in FIG. 2, the primary pressure adjusting valve 6 is closed at t2 when the cylinder residual pressure is relatively high (for example, 20 kg / cm2 G), that is, at t2 in (a), and thereafter in (b). As indicated by the broken line, the fine adjustment valve 7
Since only a small amount of nitrogen gas flows out through the
As indicated by the broken line in (a), the purge gas for protecting the catalyst can be continuously supplied for at least several hours thereafter.

[0009]

According to the present invention, as described above, by adjusting the set pressure of the primary pressure adjusting valve 6 to a value which is a fraction of the filling pressure of the cylinder 1, nitrogen gas is lost when power is lost. Even if a large amount of exhaust gas is released in excess of the required amount of combustible gas purge, the primary pressure regulating valve 6 is left with a sufficient amount for catalyst protection.
Is closed, and thereafter, a small flow rate of nitrogen gas can be continued to flow for a long time through the fine flow rate valve or orifice 7. Therefore, there is no risk of damage to the catalyst even if power is not restored for a long time after power loss, and There is an advantage that the staff does not have to rush to replace the cylinder at the time of power failure like this.

[Brief description of drawings]

1 is a system diagram of a conventional device of this type.

FIG. 2 is a system diagram of the device of the present invention.

FIG. 3 is a graph showing the operation of the device of the present invention in comparison with a conventional example, in which (a) is a graph showing a change in cylinder residual pressure and (b) is a graph showing a change in purge gas flow rate.

[Explanation of symbols]

 1 Nitrogen cylinder 2 Cylinder collecting pipe 3 Pressure reducing valve 4 Main solenoid valve 5 Micro solenoid valve 6 Primary pressure regulating valve 7 Valve or orifice 8 Main flow regulating valve 9 Micro flow regulating valve 10 Pressure gauge 11 Safety valve A Fuel cell B Cylinder unit C Fuel Battery body D control device

Claims (1)

[Claims] 1. A cylinder unit in which a pressure reducing valve is installed in a cylinder collecting pipe to which a nitrogen cylinder is connected is connected to a fuel cell main body through a main solenoid valve of a current-closed type, and in parallel with the main solenoid valve. An energization-closed type minute flow solenoid valve was connected, and when the fuel cell was not operating, the main solenoid valve was opened to purge combustible gas for a certain period of time, and then only the minute flow solenoid valve was opened to protect the catalyst. In the fuel cell purging device, a primary pressure adjusting valve is provided in the cylinder collecting pipe on the inlet side of the pressure reducing valve, and a minute flow valve or orifice is provided in parallel with the primary pressure adjusting valve.