JP3360766B2 - Fuel cell purge device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for purging (replacing) combustible gas remaining inside a fuel cell when the operation of the 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 extracting electricity by reacting hydrogen and oxygen, and the like. Therefore, it is necessary to purge the internal combustible gas, and after purging the combustible gas, it is necessary to protect the catalyst with nitrogen gas so as not to be damaged by contact with oxygen or water vapor. FIG. 1 shows a conventional fuel cell purging apparatus, in which 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 body C via the energized closed main solenoid valve 4 and an energized closed micro flow 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 flown for a certain time to purge the combustible gas in the system, and then the valve 4 is closed.
Thereafter, nitrogen gas is continuously or intermittently flowed during the operation stop period only by the micro flow rate solenoid valve 5 for protecting the catalyst, thereby protecting the catalyst of the fuel reformer and the cell stack. The reason why the main solenoid valve 4 and the minute flow rate solenoid valve 5 are energized and closed is to open the solenoid valves at the time of a power failure and to flow purge gas to ensure safety.

[0003]

However, in the above configuration, when the power supply for controlling the fuel cell is lost due to a power failure or a failure, the energized closed solenoid valves 4 and 5 are opened. The flammable gas is replaced with nitrogen gas to ensure safety, but if the power loss time is too long, all the nitrogen gas accumulated in the cylinder will be exhausted, and then purging to protect the catalyst will continue. become unable.
If the purging 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 so that a large amount of purge gas is discharged for a certain period of time (for example, 10 minutes) required for combustible gas purging.
However, there is a problem in terms of reliability in view of the fact that the operation is rarely stopped in addition to the cost. Therefore, there was a problem that the attendant rushed to the site even at midnight and had to replace it with a new cylinder before the nitrogen cylinder became empty (for example, within 30 minutes after a 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 apparatus which does not hinder catalyst protection even when the power supply loss time is 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 electromagnetic valve 4 for combustible gas purging, and an energization for catalyst protection is performed in parallel with the main electromagnetic valve 4. For a fuel cell in which a closed micro solenoid valve 5 is connected, the main solenoid valve is opened when the operation of the fuel cell is stopped, combustible gas is purged for a certain time, and then only the micro flow solenoid valve is opened to protect the catalyst. In the purge device, a primary pressure adjustment for opening the inlet side of the pressure reducing valve 3 with a gas pressure of a certain value or more.
With the valve 6 interposed, the above-mentioned constant value is set to a fraction of the cylinder filling pressure.
The primary pressure regulating valve 6 is provided with a valve or an orifice 7 having a small flow rate in parallel with the primary pressure regulating valve 6.

[0005]

According to the above-mentioned structure, the set pressure of the primary pressure regulating valve 6 can be adjusted to a value which is about a fraction (for example, 20 kg / cm2 G) of the filling pressure of the cylinder 1 (150 kg / cm2 G). For example, even if a power loss occurs and a large amount of nitrogen is released, the primary pressure regulating valve 6 is shut off leaving a sufficient amount of nitrogen gas for protection of the catalyst. Purging with a flow of nitrogen gas can be ensured, so that there is no risk of damaging the catalyst over long periods of power loss.

[0006]

FIG. 2 shows an embodiment of a fuel cell purging apparatus according to the present invention. In a cylinder unit B, a pressure reducing valve 3 is connected to a cylinder collecting pipe 2 to which a plurality of nitrogen gas cylinders 1 are connected.
The pressure reducing valve 3 allows the normal filling 1
50kg / cm2 G cylinder pressure 5-10kg / cm
The pressure is reduced to 2 G and sent to the fuel cell A. A primary pressure regulating valve 6 is interposed in the cylinder collecting pipe 2 on the inlet side of the pressure reducing valve 3, and a valve or an orifice 7 having a small flow rate is provided in parallel with the primary pressure regulating valve 6. On the side of the fuel cell A to be connected, an energized closed main solenoid valve 4 that closes the valve when energized at the connection port, and an energized closed micro solenoid valve 5 for catalyst protection is connected in parallel with the main solenoid valve 4. Have been. In the figure, reference numeral 8 denotes a main flow control valve, and 9 denotes a fine flow control valve.

In use, the set pressure of the primary pressure regulating valve 6 is set to a value which is a fraction of the filling pressure of the cylinder 1 (20 to 30).
kg / cm2 G). When the power supply of the control device D is lost, the main solenoid valve 4 and the minute flow rate solenoid valve 5, which are energized and closed, are opened, and a large amount of nitrogen is released from the cylinder unit B at the secondary pressure of the pressure reducing valve 3 (for example, 6 kg / cm2 G). It is released, for example, after 30 minutes, the cylinder pressure becomes 20 kg / cm 2 G
When the pressure drops to below, the primary pressure regulating valve 6 detects this and closes the valve. Thereafter, a small flow rate of nitrogen gas is supplied to the fuel cell A at 6 kg / cm 2 G only through the orifice 7, and the power supply is maintained for several tens of hours thereafter. Is maintained, the purge gas for protecting the catalyst is maintained. In the figure, 10 is a pressure gauge, and 11 is a safety valve.

FIG. 3 shows a comparison between the operation according to the conventional configuration (solid line) and the operation according to the configuration of the present invention (dashed line).
Indicates the cylinder residual pressure, and (b) indicates the amount of outflow from the cylinder. According to the conventional configuration shown in FIG. 1, when the power supply is lost at t0, the two solenoid valves 4 and 5 on the fuel cell side are opened, so that the purge gas is set by the main flow control valve 8 as shown in FIG. Since the main solenoid valve 5 is not controlled even after the combustible gas has been purged at t1, the pressure is reduced by the pressure reducing valve 3 to a constant pressure (for example, 6 kg / c).
m2 G) and continue to flow at substantially the same flow rate.
Then, as shown in (a), at t3, the primary pressure becomes 6
After the pressure becomes less than kg / cm 2 G, the flow rate becomes 0 shortly thereafter. On the other hand, in the configuration of the present invention shown in FIG. 2, the primary pressure regulating valve 6 is closed at the time when the cylinder residual pressure is relatively high (for example, 20 kg / cm @ 2 G), that is, at t2 in FIG. As indicated by the dashed line, the minute adjustment valve 7
Only a small amount of nitrogen gas flows out through
As shown 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 setting the set pressure of the primary pressure regulating valve 6 to a value which is about a fraction of the filling pressure of the cylinder 1, the nitrogen gas is supplied when the power is lost. Is released in a large amount exceeding the required amount of the combustible gas purge, the primary pressure regulating valve 6 is left with a sufficient amount for protecting the catalyst.
The valve closes, and thereafter a minute flow of nitrogen gas can be continued to flow through the minute flow valve or the orifice 7 for a long time. There is an advantage that it is no longer necessary for the attendant to rush to replace the cylinder in the event of a power outage. Further, the primary pressure regulating valve 6 is connected to the fuel cell equipment A side.
Not controlled by control device D, gas pressure
Only passively and mechanically operated by
Is extremely reliable in the event of an abnormality.
There is a point.

[Brief description of the drawings]

FIG. 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.

FIGS. 3A and 3B show the operation of the apparatus of the present invention in comparison with a conventional example, in which FIG. 3A is a graph showing a change in cylinder residual pressure, and FIG. 3B is a graph showing a change in purge gas flow rate.

[Explanation of symbols]

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

Claims (1)

(57) [Claims] 1. A cylinder unit having a pressure reducing valve interposed in a cylinder collecting pipe connected to a nitrogen cylinder is connected to a fuel cell main body through a main solenoid valve of an energized closed type, and is connected in parallel with the main solenoid valve. A micro-flow solenoid valve of an energized closed type was connected, and when the operation of the fuel cell was stopped, the main solenoid valve was opened to perform flammable gas purging for a certain time, and then only the micro-flow solenoid valve was opened to protect the catalyst. In the fuel cell purge device, a primary valve that opens at a gas pressure equal to or higher than a certain value at an inlet side of the pressure reducing valve.
With the pressure regulating valve interposed, keep the above constant value several minutes of the cylinder filling pressure.
A fuel cell purging apparatus comprising a valve or an orifice with a small flow rate set in parallel with the primary pressure regulating valve.