JPH09293522A - Safety device for fuel cell power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance safety even with a comparatively simple structure in a safety device preventing an explosion accident resulting from ignition to the hydrogen of a fuel cell power generation device using the hydrogen as raw fuel. SOLUTION: The safety device 15 of a fuel cell power generation device 1 is equipped with a fuel system pipeline 5 which feeds hydrogen from a hydrogen feeding pipe 7 to the fuel electrode 3 of a fuel cell main body 2, shutoff valves 18, 22 which shut off the pipeline are provided in the fuel pipeline 5, and simultaneously second to fifth purging branch pipes 32 to 35 which extend from an inert gas source such as a nitrogen gas feeding pipe 27 or the like, and provided with second to fourth purging valve 32a to 34a to the downstream than the shutoff valves 18, 22 of the fuel pipeline 5. The second to the fourth purging valves 32a to 34a are controlled so as to conduct valve opening operation before the shutoff operation of the shutoff valves 18, 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for stopping a fuel cell power generator.

[0002]

2. Description of the Related Art In some fuel cells, hydrogen is supplied as a raw fuel to a fuel electrode and air is supplied to an air electrode to generate electricity by an electrochemical reaction.

In a fuel cell power generator using this type of fuel cell, it is necessary to continuously supply hydrogen and air to the fuel electrode and the air electrode, respectively, during the power generation. And an air line are installed.

Since hydrogen and air supplied to each electrode through these pipes may explode when they are mixed and ignited, when such a fuel cell power generator stops, A safety device for purging inert gas such as nitrogen is installed in the pipeline of each system to reduce the risk of explosion.

In such a conventional safety device, the purging of the inert gas is performed by shutting off the shut-off valve for shutting off the pipeline of each system from the hydrogen source or the air source, and purging the inert gas to the pipeline of each system. It is said that the opening operation of the purge valve for purging is performed at the same time.

[0006]

By the way, in such a conventional safety device, when the shutoff valve and the purge valve are operated simultaneously at the same time, the inside of the pipeline of each system is purged with an inert gas. It can be in a state.

However, when there is a variation in the operation of the shutoff valve and the purge valve, the shutoff valve is actuated first and the purge valve is opened thereafter, or when the pressure of the inert gas is low, etc. A negative pressure state is temporarily generated in the pipeline of.

When this negative pressure state occurs in the fuel system pipeline, air is sucked into the pipeline due to the negative pressure, and hydrogen and air are mixed in the fuel system pipeline. It is hard to say that there is no danger of explosion in such cases.

For example, when the safety device is activated and an emergency stop occurs due to ignition of the exhaust port of the fuel cell power generator due to a lightning strike or the like on the fuel cell power generator, a negative pressure is temporarily applied to the inside of the fuel system pipeline. When this happens, a flashback occurs in the fuel system pipeline, and the flame is transmitted to the upstream hydrogen source.Preventing this will greatly improve the safety of the stopped fuel cell power generator. It will be.

The present invention has been made under these circumstances, and is relatively simple in a safety device for preventing an explosion accident due to ignition of hydrogen in a fuel cell power generator using hydrogen as a raw fuel. , The issue is to improve its safety.

In order to solve this problem, the invention according to claim 1 has a fuel system conduit for supplying hydrogen from a hydrogen source to the fuel electrode of the fuel cell body, and this fuel system A fuel cell in which a shutoff valve for shutting off the pipeline is provided in the pipeline, and an inert gas pipeline extending from an inert gas source and provided with a purge valve is connected to the downstream side of the shutoff valve of the fuel system pipeline. In the safety device of the power generator, the purge valve is controlled so as to be opened prior to the shutoff operation of the shutoff valve.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings.

In the drawings, reference numeral 1 denotes a fuel cell power generator, which has a phosphoric acid type fuel cell main body 2 therein.

The fuel cell main body 2 has a fuel electrode 3 and an air electrode 4, and hydrogen gas as a raw fuel is supplied to the fuel electrode 3 to cause an electrochemical reaction to generate electricity.

In the fuel cell power generator 1, the fuel electrode 3 is provided with a fuel system conduit 5 extending from a hydrogen source.

Further, the air electrode 4 of the fuel cell power generator 1
The air system pipeline 6 extended from the air source is installed in the.

In this embodiment, the fuel line 5
Connects a hydrogen feed pipe 7 (corresponding to a hydrogen source) that feeds by-product hydrogen gas in a chemical plant to the fuel electrode 3, and the fuel system pipe 5 passes through the fuel electrode 3. After that, it reaches the exhaust portion 8 formed in a chimney shape of the fuel cell power generator 1.

On the downstream side of the fuel electrode 3, a fuel branch pipe 11 is branched from the fuel system pipe line 5, and the other end of the fuel branch pipe 11 is arranged on the upstream side of the fuel electrode 3. Connected to form a circulation circuit. As a result, most of the unreacted hydrogen is sent to the fuel electrode 3 again together with the newly supplied hydrogen, and the hydrogen utilization efficiency is improved.

On the other hand, an air system conduit 6 connected to the air electrode 4
Is one in which one end is opened to the atmosphere and the other end is located in the exhaust part 8 through the air electrode 4, and the air system pipe 6 is for sucking the atmosphere to the one end side from the air electrode 4. It has an air blower 13.

Therefore, hydrogen is supplied to the fuel electrode 3 of the fuel cell main body 2 by the fuel system conduit 5 and air is supplied to the air electrode 4 by the air system conduit 6, so that the fuel cell main body 2 can generate electricity. In the above, the required power generation is continuously performed as in the known phosphoric acid fuel cell.

In the fuel cell power generator 1, a safety device 15 constructed as follows is attached to the fuel system pipeline 5 and the air system pipeline 6.

The safety device 15 is inactive in the shutoff valves and the like installed in the fuel system pipeline 5 and the air system pipeline 6 and in the fuel system pipeline 5 and the air system pipeline 6 and the like. It comprises a purging device 16 for purging gas.

That is, in the fuel system pipeline 5, a manual shutoff valve 17, a first shutoff valve 18, a flame arrester 21, and a second shutoff valve 22 arranged in series in the fuel system pipeline 5 as a pair. Are sequentially arranged on the upstream side of the ejector 12,
A circulation control valve 23 is arranged in the fuel branch pipe 11.

In addition, an air shutoff valve 25 that shuts off the air line 6 is installed between the air blower 13 and the air electrode 4.

The purging device 16 is constructed as follows.

The purging device 16 includes a nitrogen source for supplying nitrogen as an inert gas, a purge conduit 26 extending from the nitrogen source to the fuel system conduit 5 and the air system conduit 6, and a purge conduit. 26 and each normally-closed purge valve installed at 26.

In this embodiment, the nitrogen source commonly used is the nitrogen gas feed pipe 27, and the pressure sensitive switching valve 2
Nitrogen gas cylinder 29 for emergency backup via 8
And can be switched automatically. In addition, the purge line 26 extends from the nitrogen source, and the tip of the purge line 26 branches into five purge branch pipes 31 to 35 and the fuel system line 5 is divided.
And, it is connected to a required portion of the air system pipeline 6.

The first purge branch pipe 31 is branched downstream of the pressure sensitive switching valve 28 in the purge pipe line 26, and is located between the first shutoff valve 18 and the flame arrester 21 in the fuel system pipe line 5. It is connected via the first purge valve 31a.

The second purge branch pipe 32 is branched downstream of the branch portion of the first purge branch pipe 31,
The second purge valve 32a is connected between the air shutoff valve 25 of the air system conduit 6 and the air electrode 4.

The third purge branch pipe 33 is branched downstream of the branch portion of the second purge branch pipe 32.
It is connected to the upper part of the air system pipeline 6 located in the exhaust section 8 via a third purge valve 33a.

The fourth purging branch pipe 34 and the fifth purging branch pipe 35 are provided with a fourth purging valve 34a located downstream of the branching portion of the third purging branch pipe 33.
The fourth purging branch pipe 34 is connected to the upstream side of the ejector 12 of the fuel branch pipe 11, and the fifth purging branch pipe 35 is connected to the fuel system conduit 5 immediately before the fuel electrode 3 via ing.

As will be described later, the safety device 15 performs a required operation by controlling and operating each valve by the computer 36. In the illustrated embodiment, two thermocouples 37 are installed above the air pipe 6 of the exhaust unit 8 so that ignition of hydrogen due to lightning strike or the like can be detected. .

For example, when ignition of hydrogen is detected by the thermocouple 37 due to a lightning strike on the fuel cell power generator 1, the ignition signal is transmitted to the computer 36, and the computer 36 informs the fuel cell. In addition to outputting required stop signals such as cooling of the main body 2 and stop of the air blower 13 to various parts of the device, the safety device 15 also outputs open / close command signals for each valve as follows ( See FIG. 2).

That is, the computer 36, to which the ignition signal is transmitted, tells the computer 36 to the second to fourth purge valves 32a to 34a.
And a bypass passage valve 39 installed in parallel with the manual throttle valve 38 in the fuel system pipe line 5 on the downstream side of the fuel electrode 3,
The drive signal is output toward the circulation control valve 23 and the air cutoff valve 25.

In response to a drive signal from the computer 36, the second to fourth purge valves 32a to 34a and the bypass passage valve 39 immediately open the pipeline, but the circulation control valve 23 and the air cutoff valve. 25 fully closes the pipeline.

As a result, the nitrogen from the nitrogen source is supplied to the hydrogen existing downstream of the second shutoff valve 22 in the fuel system pipeline 5 and to the downstream portion of the air shutoff valve 25 in the air system pipeline 6. The existing air and the air are released into the atmosphere, and the respective pipelines 5 and 6 are filled with nitrogen gas to be in a purged state.

In this embodiment, the effective diameter of the manual throttle valve 38 is set to a small diameter due to the fact that most of the unreacted hydrogen is circulated to the fuel electrode 3 in the fuel branch pipe 11. When purging nitrogen gas, in order to ensure a flow rate of nitrogen gas and complete the purging quickly,
The bypass passage valve 39 having a large effective diameter is used.

Further, in the above-mentioned purging of nitrogen gas, since the pressure of nitrogen gas is considerably higher than the pressure of hydrogen gas, hydrogen gas is being supplied to the fuel system pipeline 5. There is no problem.

Then, the computer 36, for the first and second shutoff valves 18 and 22 installed in the fuel system pipeline 5, sets the inside of the pipelines 5 and 6 in the purged state as described above. After that, a cutoff signal is output and the cutoff operation is performed.

As described above, since the shutoff valves 18 and 22 shut off the fuel system pipeline 5 after the fuel system pipeline 5 is filled with the nitrogen gas first, the inside of the pipeline 5 is not made negative pressure. It is possible to prevent air from being sucked into the fuel system conduit 5.

The air shutoff valve 25 of the air line 6 is designed to be shut off at the same time as the opening of the second purge valve 32a as described above. This is the second
The purpose of purging by the purge valve 32a is different from the case of the fuel system conduit 5 to reduce the power generation reaction due to the residual oxygen in the air electrode 4 by eliminating the air remaining in the air electrode 4 to the outside. This is because it protects the battery.

Therefore, when the main purpose is to prevent an explosion accident due to ignition of hydrogen as in the present application,
The installation of the second purge branch pipe 32, the second purge valve 32a, and the air shutoff valve 25 may be omitted.

As described above, in this embodiment, the fuel system pipeline 5 is mainly provided in the downstream side of the second shutoff valve 22 and the air system pipeline 6 in the downstream side of the air shutoff valve 25. Is in a purged state filled with high-concentration nitrogen gas, so even if a fire due to a lightning strike or the like might reach the downstream side portion of the fuel system pipeline 5, there is no flashback, The risk of explosion due to ignition of the fuel line 5 is reduced.

Although the first purge valve 31a is not operated in the above-described embodiments, it goes without saying that the first purge valve 31a may be operated if necessary. .

[0044]

As described above, according to the first aspect of the invention, in the safety device of this type of fuel cell power generator, the purge valve is installed prior to the shutoff operation by the shutoff valve in the fuel system pipeline. Since the valve is reliably opened and the purge of the inert gas in the fuel system pipeline is started, the inside of the fuel system pipeline does not become a negative pressure state, and the air is sucked into the fuel system pipeline. As a result, it is possible to prevent the inside of the pipeline from being in a mixed state of hydrogen and air, and safety is improved.

Moreover, prior to the shutoff operation of the shutoff valve,
Since the purge valve is controlled so as to be opened, it can be implemented relatively easily, and particularly when it is controlled using a computer, it can be implemented very easily by a program.

[Brief description of drawings]

FIG. 1 is an overall schematic explanatory view of a safety device of a fuel cell power generator.

FIG. 2 is a control block diagram when hydrogen is ignited by a lightning strike or the like.

[Explanation of symbols]

 1 Fuel Cell Power Generator 2 Fuel Cell Main Body 3 Fuel Electrode 5 Fuel System Pipeline 7 Hydrogen Feed Pipe (Hydrogen Source) 15 Safety Device 18 First Cutoff Valve 22 Second Cutoff Valve 23 Circulation Control Valve 26 Purge Line ( Inert gas pipeline) 27 Nitrogen gas supply pipe (inert gas source) 31 First purge branch pipe 31a First purge valve 32 Second purge branch pipe 32a Second purge valve 33 Third Purge branch pipe 33a Third purge valve 34 Fourth purge branch pipe 34a Fourth purge valve 35 Fifth purge branch pipe

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Hiroshi Miki 2109 Yashima Nishimachi, Takamatsu City, Kagawa 8 Shikoku Research Institute Co., Ltd. (72) Inventor Shigemitsu Kuwahara 575-1 Nakajima, Kawauchi-cho, Tokushima, Tokushima Stocks Toagosei Co., Ltd. Company Tokushima Factory (72) Inventor Yoshiaki Hara 575-1 Nakajima, Kawauchi-cho, Tokushima City, Tokushima Prefecture Toagosei Co., Ltd.Tokushima Factory (72) Inventor, Osamu 575-1 Nakajima, Kawauchi-cho, Tokushima City, Tokushima Prefecture Toagosei Co., Ltd. in the factory

Claims (1)

[Claims] 1. A fuel system conduit for supplying hydrogen from a hydrogen source to a fuel electrode of a fuel cell main body, the fuel system conduit being provided with a shutoff valve for shutting off the conduit, and the fuel system conduit In a safety device for a fuel cell power generator, which is connected to an inert gas pipeline that is provided with a purge valve and extends from an inert gas source downstream of the shutoff valve, the purge valve prior to the shutoff operation of the shutoff valve. A safety device for a fuel cell power generation device, which is controlled so as to open the valve.