JPS59149660A - Fuel-cell power generating system - Google Patents

Abstract

PURPOSE:To prevent any accidents by detecting contamination by minute amounts of fuel gas and oxidant gas which develop in an emergency such as cell disorder by installing a CO2 gas detector near the cell body in a piping on the outlet side of an air electrode. CONSTITUTION:A fuel cell body 1 is constituted by installing catalyst layers 12 and 13 on both sides of an electrolyte layer 11 before a fuel and an air electrode 14 and 15 respectively are installed on the catalyst layers 12 and 13. When methane of 100% purity for example is taken as a fuel from the inlet 21 of a fuel reformer 2, reformed gas existing in the outlet of the reformer 2 is composed of carbon dioxide, about 70% hydrogen and a little less than 0.2% carbon nonoxide. If any bad condition arises in the catalyst layer 11 producing contamimation by a minute amount of gas between the fuel and the air electrode sides, increase in carbon dioxide concentration is detected with a carbon dioxide detector 3 installed near the outlet 25 of the air electrode 15 thereby enabling the bad condition to be known. This enables gas leakage to be detected earlier than a hydrogen detector and secures the safety of the device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a single fuel pond starter device, and particularly to protection in the event of a failure thereof.

[Technical background of the invention and its problems]

The basic structural unit of a fuel cell is a unit cell, which has an electrolyte layer at its center, catalyst layers on both sides, and four poles on both sides. A unit cell 1 consisting of these 5 layers in total
-1 The unit cells described above are integrated while maintaining a structure in which the fuel gas is fully supplied to one side of the unit cell, and the oxidizing gas such as air can be supplied to the other side. The main body of the fuel cell is constructed as follows. When using a fuel cell configured in this way as a starter, the fuel electrode side is generally An inlet and an outlet for gas supply are provided on the and air electrode sides, respectively, and an excess of gas exceeding the theoretically necessary gas flow rate for the electromotive reaction is supplied.
Use with a flow on each pole.

In fuel cell power generation equipment, hydrocarbons are generally used as fuel in the summer, and water vapor is added to this and sent to a fuel reformer to produce a gas containing hydrogen as the main component, carbon dioxide (carbon dioxide gas), -carbon oxide, etc. Modify and use. Among these gas components, for example, in a phosphoric acid fuel cell, only hydrogen gas takes part in the reaction, while in a molten carbonate fuel cell, hydrogen and carbon oxide gas take part in the reaction. It is also common to use air as an fc tilling agent, and in this case, nitrogen, which is the main component of air, is discharged from the fuel cell air electrode outlet without being used.

The reformed gas and air supplied to the fuel cell are strictly separated in the alpha pond, and mixing of these two gases generally does not occur. For example, in the case of the phosphoric acid type, hydrogen mainly diffuses in a gaseous state at the fuel electrode, and when it reaches the catalyst layer, it becomes hydrogen ions through an oxidation reaction.

Therefore, under normal conditions, only ions pass through the electrolyte layer, and no gas passes through it. This fact that only ions pass through the electrolyte layer does not change in other fuel cells, such as the molten carbonate type. However, since the hydrogen in the reformed gas used is a gas with an extremely wide explosion range, when using one fuel tank as an ignition device, consideration must be given to the mixing of gas in an emergency to ensure safety. It is necessary to have means in place to ensure this. It is especially important to predict contamination before it leads to a major accident, and if an extremely narrow pinhole or crack occurs in the Quhebo layer and all the gas from the four solute layers passes through, a trace amount of gas will be detected. By detecting all of these, it is necessary to shut off one fuel gas inlet and purge the inside of the battery with inert gas to prevent accidents.

By the way, as a means of detecting gas contamination in the fuel cell body in an emergency, conventionally a gas detector for hydrogen, which is the main component of fuel gas, is installed in the outlet manifold or piping on the air electrode side. An oxygen gas detector gold film was placed on the side outlet manifold or piping near the battery to detect the contamination of gas components from the respective electrodes. However, with this method, it is not possible to detect the inclusion of a trace amount of gas for reasons described later.

[Purpose of the invention]

An object of the present invention is to provide a fuel cell power generation system that detects minute amounts of mixture of fuel gas and oxidizing gas that occur in a fuel cell in the event of an emergency such as a battery failure, thereby preventing the occurrence of an accident. This is what we provide.

[Embodiments of the invention]

The first point of the present invention lies in the discovery of the fact that gas that passes through the electrolyte layer fails to react in the catalyst layer on the opposite electrode side. For example, when a very small amount of hydrogen on the fuel electrode side passes through the electrolyte layer and reaches the air electrode, it reacts with oxygen in the air on the catalyst layer on the air electrode side and becomes water (steam). If a situation occurs where the hydrogen gas reaches the air electrode and passes through it, the amount of hydrogen gas passing through the electrolyte layer has reached such an amount that it is impossible to prevent dangerous accidents. I found it. Therefore, as is conventionally known, even if the alarm level of the hydrogen detector installed on the air electrode side is set to a value below the explosion generation limit, for example 0.1%, when this detector issues an alarm, The amount of gas in the battery has already exceeded the dangerous limit.

The second point of the present invention is that when a phenomenon in which a small amount of gas passes through the electrolyte layer occurs, carbon dioxide gas is detected at the outlet on the air phase side of p1 as long as the gas obtained by reforming hydrocarbon gas is used as fuel. The problem lies in finding out what happens. Air normally contains approximately 0.03% carbon dioxide gas, and during a normal electromotive reaction, the air electrode outlet gas contains oxygen consumed in the electromotive reaction and water vapor generated by the electromotive reaction. , no change is observed in the mass flow rate for other components. By providing a carbon dioxide gas detector near the battery body on the air electrode outlet side manifold or the outlet side air piping, for example, by setting the detection level to 0.04%, it is extremely effective.
We have discovered that this method can be an effective means of preventing danger by understanding the passage of minute gases through the electrolyte layer.

The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.

In FIG. 1, 1 is a fuel cell main body, 2 is a fuel reformer, and 3 is a carbon dioxide detector.

The fuel cell body 1 has catalyst layers 12.1 on both sides of the electrolyte layer 11.
3 are respectively provided, and then an air electrode 15 is provided on the opposite side of the fuel electrode 14. Although the configuration shown in the figure schematically shows one set of elementary ponds, it is actually made by stacking many of them, and both the fuel passage 16 and the air passage 17 are branched into many parts, and the entrance of the passage Although not shown, manifolds are provided on the side and the outlet side.

In this embodiment, the fuel reformer 2 includes a reformer, a high-temperature shift converter, a low-temperature shift converter, a few heat exchangers, etc. (not shown), and takes in water vapor in addition to fuel. From the inlet 21 of this device, for example, purity 10
When 0% methane is taken in as fuel, the dry base reformed gas composition at the reformer outlet directly connected to the fuel electrode inlet 22 of the fuel cell body 1 is about 70% hydrogen, -
The carbon oxide content is a little less than 0.2%, and the remainder is carbon dioxide.

Only the hydrogen in the reformed gas led to the large fuel port 22 of the phosphoric acid fuel cell main body of this embodiment participates in the electromotive reaction, and the remaining gas components and hydrogen remaining unreacted reach the fuel electrode. It is discharged from the outlet 23.

Oxygen in the air sent from the inlet 2'4 on the air electrode 15 side reacts in the air electrode catalyst layer 15, water (steam) is generated, and air is mixed with nitrogen and other components among the air components. It is discharged from the polar outlet 25.

When a problem occurs in the catalyst layer 11 and a trace amount of gas is mixed in between the fuel electrode side and the air electrode side (cross-o =) (-), the carbon dioxide detector 3 installed near the air electrode outlet 25 detects ), the increase in carbon dioxide concentration can be fully detected and this problem can be detected.

〔Effect of the invention〕

The effects of the present invention are compared with the conventional method of providing a hydrogen detector at the air electrode outlet, and are shown in FIG. The horizontal axis in the figure shows the amount of fuel gas leaking to the air electrode side as a percentage of the gas increment at the air electrode outlet, and the vertical axis shows the value indicated by the dry pulse gas detector.

The test results shown here are based on the oxygen utilization rate e50 on the air electrode side.
The results were investigated under constant conditions of q6, and 31 is a curve in which the indicated values of the carbon dioxide detector are plotted, and 32 is a curve in which all indicated values of the hydrogen detector are plotted. Even though normal air always contains trace amounts of carbon dioxide, it is clear that gas leaks can be detected earlier than hydrogen detectors.

It has been shown that the present invention is effective in ensuring the safety of the fuel composition generator.

The same effect was also obtained in the second embodiment in which the carbon dioxide detector was provided in the air electrode outlet manifold of the fuel cell main body.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, and FIG. 2 is a characteristic diagram showing the effects of the present invention in comparison with a conventional method. 1 - Fuel cell body 2 - Fuel reformer 3... Carbon dioxide gas detector 11 - 1 Solute layer 12 Fuel electrode catalyst layer 13 - Air electrode catalyst layer 14 Fuel electrode work 5 Air electrode
1 (i・Fuel passage 17 Air passage 21・Fuel reformer population 22・Fuel electrode inlet 23・・Fuel excavation outlet 24・Air electrode inlet 25・Air electrode outlet Patent attorney Noriyuki Chika (and 1 other person) No. l Figure 2: Guest” nnt

Claims (1)

[Claims] A fuel cell light 1 device is equipped with a device for reforming hydrocarbon fuel into a gas containing hydrogen as a main component, and generates energy by electrochemically reacting the reformed gas with an oxidizing agent such as air.
A fuel cell power generation device characterized in that a carbon dioxide (carbon dioxide gas) detector is provided on the air electrode gas outlet side of the fuel/1 pond body.