JPS5894767A - Fuel cell device - Google Patents

Abstract

PURPOSE:To detect the cross over in a cell and to improve the efficiency of pressure difference controlling by adding a concentration meter of carbon dioxide for detecting the density of carbon dioxide in an oxidizing agent discharge passage discharging the oxidizing agent from an oxidizing agent pole. CONSTITUTION:A fuel cell 4 composed of an electrolyte matrix 1, oxidizing agent pole 2, fuel pole 3, oxidizing agent passage 6 and fuel passage 7 is stored in a container 5 filled with inactive gas 8, and the pressure difference between the oxidizing agent and inactive gas is measured by a pressure differece measurement/control unit 13 and the pressure difference between the fuel and inactive gas is measured by a pressure difference measurement/control unit 14 respectively and they are controlled so as to obtain predetermined pressure differnces. In addition, a concentration meter 18 of carbon dioxide is provided in an oxidizing agent discharge passage 10 to detect an occurrence of cross over. Accordingly, the cross over can be effectively reduced to a minimum and the cell life can be extended by determining the pressure differece setting values of individual pressure difference measurement/control units 13, 14 based on the output of the concentration meter 18.

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a fuel cell device, and particularly to a fuel cell device suitable for detecting the degree of leakage of fuel from a fuel electrode to an oxidizer electrode and detecting an abnormality in a fuel cell. This invention relates to a fuel cell device.

Prior Art and Problems with the Prior Art FIG. 7 is a sectional view showing the basic structure of a fuel cell, and schematically represents the phenomena that occur inside the fuel cell. In the figure, l is an electrolytic solution matrix in which a phosphoric acid electrolyte is held in a layer made of a nonwoven fabric of phenolic gauze or layered silicon pattern particles. The base material is carbon vapor, and a catalyst such as platinum is applied to the surface in contact with the electrolyte matrix, and a catalyst such as platinum is applied to the opposite surface to prevent the formation of sludge due to the solution and to form a three-phase interface. An oxidizer electrode and a fuel electrode as gas diffusion electrodes having a water-repellent treatment to make them easier to manufacture;
? and J are carbon plates arranged on the outside of the oxidizer electrode and the fuel electrode 3, respectively.

In such a configuration, a cell made up of an electrolyte, an oxidizer electrode, and a fuel electrode is called a single cell, and is generally manufactured in an integrated manner. When stacking these single cells to form a fuel cell stack, the nine single cells are electrically connected in series and the fuel electrode 3 is injected with fuel! of,
Further, carbon plates 〃, 〃/de having gas flow paths 1 for supplying the oxidizing agent to the oxidizing agent electrodes are interposed as basic constituent elements.

Under normal operating conditions, ■ in the fuel flow is at the fuel electrode 3.
B on the surface of the oxidizer pole, which moves in the electrolyte of the electrolyte matrix l toward the oxidizer &λ side, and on the surface of the oxidizer pole, the 0. H and O are generated by reacting with the 0'''' generated from the oxidizer.At this time, e-ions flow from the fuel electrode J side to the oxidizer electrode side through the external circuit, resulting in obtaining DC power. This is something that can be done.

In other words, the electrode reaction in a fuel cell is a reaction in the coexistence of a fuel gas or an oxidant gas, a catalyst, and an electrolyte, that is, a reaction in the gas phase,
Since this is an interfacial reaction in the coexistence of solid and liquid J phases,
In order to maximize the performance of the fuel cell, this J-phase interface must be maintained and controlled strictly, and the differential pressure between the fuel electrode 3 and oxidizer electrode must be controlled extremely well! This is a serious problem.

As outlined above, fuel cells are extremely brittle and easily damaged, as the members constituting the cells are made of carbon paper, and the J-phase interface during electrode reactions Due to requirements such as the need to maintain and control the fuel, the differential pressure between the electrode J and the oxidizer must be extremely strictly controlled. There is also ψI that is controlled so that it falls within the range.

When the pressure difference between the fuel electrode J and the oxidizer green increases in the fuel cell, the fuel or oxidizer leaks through the electrolyte matrix l layer to the other electrode, and the oxidizer or oxidizer leaks out to the other electrode. Causes a catalytic combustion reaction with fuel? ! Furthermore, if a large amount of this leakage occurs, there is a possibility that the electrode pad and the fuel cell components themselves will start to burn due to combustion heat, resulting in a dangerous situation.

This leakage phenomenon is called crossover,
The occurrence of crossover means that the proportion of fuel and oxidant consumed by direct combustion increases without contributing to the cell reaction, which increases the efficiency of fuel use and oxidation in the fuel cell. This will reduce the efficiency of using the agent and reduce the overall efficiency of the fuel cell. Therefore, it is necessary to minimize this crossover in fuel cells.

Figure J is a schematic configuration diagram of a conventional fuel cell device configured to minimize crossover. 4 is a container for storing the main body, 4 is an oxidizer flow path that supplies the oxidizer to the oxidizer electrode, 1 is a fuel flow path that supplies fuel to the fuel electrode 3, and Filled with nitrogen, an inert gas in argon,
t is an oxidizing agent supply path that supplies an oxidizing agent to the oxidizing agent flow path 6;
O is an oxidizing agent discharge path for discharging the oxidizing agent from the extenuating agent flow path 6;
// is a fuel supply path that supplies fuel to the fuel flow path, 12 is a fuel discharge path that discharges fuel from the fuel flow path, and 13 is the oxidizer flow path 4 and the container! a differential pressure controller for measuring and controlling the differential pressure between the inert gas atmosphere and the surrounding air;
41 is a differential pressure measuring controller for determining and controlling the differential pressure between the fuel flow path 7 and the atmosphere surrounding the inert gas in the container j, and /j is provided in the oxidizer discharge path IO. A control valve 14 is provided in the fuel discharge path 1 to control the pressure in the oxidizer flow path 6, a control valve 17 is provided in the fuel flow path 6, and 17 is a container! This is an inert gas supply path that supplies inert gas into the interior of the chamber.

In this configuration, differential pressure control is performed to minimize crossover within the fuel cell body.

That is, based on the pressure of the inert gas sealed in the container housing the fuel cell stack, the pressure in the oxidation 11111m path 6 is set to be slightly lower than this pressure, and the fuel IP+ flow path? Set the differential pressure in the differential pressure 11JV controllers /3 and /41 in advance so that the pressure inside the vessel is slightly lower than that in the vessel, and set the control valve /j to ensure the set differential pressure.
t, /A are controlled.

Therefore, the oxidant flow path & fuel flow path 7 and the container! The pressure of the inert gas t in the tank is controlled to be as low as the pressure of the inert gas 1, the pressure of the oxidizer flow path 6, and the pressure of the fuel flow path 7. The reason for this control is to reduce the risk of fuel and oxidizer leaking into the storage container of the fuel cell device and causing an explosion, and to reduce the pressure on the fuel flow side to prevent the oxidizer from leaking into the storage container of the fuel cell device. The reason why the pressure was set lower than that on the stream side was to take into account that hydrogen in the fuel has a tendency to leak easily.

By the way, from the perspective of minimizing crossover,
It is desirable that the pressure in the oxidizer flow path 6 and the pressure in the fuel flow path be controlled so that they are as close to each other as possible while satisfying the above-mentioned magnitude relationship. In order to do so, an effective means for determining whether or not crossover is occurring is required.

In addition, the viscous resistance within the electrolyte matrix l changes greatly depending on the temperature, and furthermore, during long-term operation, the electrolyte seeps out of the electrolyte matrix l, causing the level of the electrolyte layer to change. There is also a possibility that the likelihood of loss over occurrence changes over time, and from this point of view as well, an effective means for detecting loss over is required.

In response to such demands, conventional fuel cell devices do not have a function to effectively detect crossover, and therefore have a problem in that efficient differential pressure control cannot be performed.

Purpose of the Invention Accordingly, the purpose of the present invention is to solve the problems of the prior art described above.
Accurately detect crossover in fuel cells,
An object of the present invention is to provide an f# pressure control device that enables efficient differential pressure control.

Structure of the Invention In order to achieve the above object, the present invention provides a fuel cell device including a fuel cell main body comprising an oxidizing agent electrode and an oxidizing electrode arranged on both sides of an electrolyte, and a fuel cell main body sealed in an inert gas. It consists of a container for storing the oxidizing agent, an oxidizing agent discharge path for discharging the oxidizing agent from the oxidizing agent discharge channel, and means for detecting the 111 degrees of carbon dioxide in the acid stifling agent discharge channel.

Examples of the invention Hereinafter, embodiments of the present invention will be explained according to the drawings.

FIG. 3 is a schematic configuration diagram of a fuel cell device according to an embodiment of the present invention, and the difference between the configuration in the diagram and the configuration in FIG.
The reason is that a carbon dioxide #1 degree meter 18 is provided in the chemical agent discharge path io.

In this configuration, the oxidant flow path 6 is connected from the oxidant supply path D to the oxidant flow path 6.
The oxidizer supplied therein and the fuel supplied from the fuel supply channel // into the fuel flow path react within the fuel cell body to generate necessary DC power.

Note that the pressure difference between the pressure of the oxidant in the oxidizer flow path 6 and the pressure of the inert gas t in the volume lit is measured by a differential pressure measurement controller 13,
The control valve is so that this becomes the desired preset differential pressure.
The oxidizing agent is discharged from the oxidizing agent discharge path 10 by controlling the oxidizing agent flow path 10 to maintain the differential pressure with respect to the inert gas t in the oxidizing agent flow path 4. On the other hand, the pressure of the fuel in the fuel flow path 7 and the passenger equipment! The pressure difference of the inert gas in the tank is measured by a differential pressure measurement controller, and this becomes a preset desired differential pressure, which controls the control valve to discharge fuel from the fuel discharge path. is discharged to maintain a differential pressure with respect to the inert scum t in the fuel flow path. In addition, while maintaining the relationship that the set differential pressure set in each differential pressure measurement controller /J, /4I decreases in the order of inert gas j, oxidizer flow path 6, and fuel flow path 7, cross-over The profit is set to a level that is close to the level that does not occur.

Note that the crossover occurs in the oxidant discharge path i.

The set differential pressure of each differential pressure measurement controller /3 and /da is determined by the carbon dioxide concentration meter /j installed in the middle of the carbon dioxide concentration meter /j, and the set differential pressure of each differential pressure measurement controller /3 and /da is determined according to the output of the carbon dioxide concentration meter it so that crossover 91 does not occur. Set in range.

By the way, next, the W principle of crossover detection using a carbon dioxide concentration meter/g will be explained. Gas obtained from petroleum through a steam reforming process is generally used as a fuel for fuel cells, and its composition is 10 degrees of hydrogen and Kss of carbon dioxide. Therefore, when the fuel penetrates the electrolyte matrix l and enters the oxidizer flow path A due to the occurrence of crossover, the carbon dioxide concentration in the oxidizer flow path 6 decreases because carbon dioxide does not react with the oxidizer. To increase. Therefore, the degree of crossover can be determined by measuring the concentration of carbon dioxide in the oxidizing agent discharge passage 10 that discharges the acid 4ff agent from the oxidizing agent passage 6 using the carbon dioxide concentration meter IT.

Therefore, based on the output of the carbon dioxide concentration meter it.

By determining the differential pressure settings of each differential pressure measurement controller/3 and 1 within a range that can minimize the crossover, it is possible to effectively and efficiently minimize the loss over. As a result, the usage conditions of fuel cells! & Due to optimization, battery life can be extended. Furthermore, the performance or deterioration of the fuel cell can be determined based on the output of the carbon dioxide concentration meter IT.

Modifications of the Invention In the above embodiments, the case where the carbon dioxide concentration meter IT was provided alone was exemplified.

Carbon dioxide concentration meter/g and each differential pressure measurement controller/J,/41
It may also be configured such that the differential pressure is automatically set by organically combining the two.

Effects of the Invention As described above, according to the present invention, it is possible to efficiently operate a fuel cell while minimizing sover, and to obtain a fuel cell device that is effective in extending the life of fuel ionization. It is something that can be done.

[Brief explanation of drawings]

FIG. W41 is a sectional view showing the basic structure of a fuel cell, FIG. 1 is a schematic diagram of a conventional fuel cell device, and FIG. 3 is a schematic diagram of a fuel cell device according to an embodiment of the present invention. C... Electrolyte matrix, C... Oxidizer electrode, 3...
Mole #+pole, G...Curative agent flow path,? ...Fuel flow path!
... Container, /3, IQ ... Differential pressure measurement controller, /! ,
/! ...control valve, /l...carbon dioxide concentration meter. Applicant's representative: Kiyoshi Inomata, 1st prisoner

Claims (1)

[Scope of Claims] 1. A fuel cell body comprising an oxidizer electrode and a fuel electrode disposed on both sides of a solute, a container in which the fuel cell body is hermetically housed in an inert container, and an oxidizer electrode. 1. A fuel cell device comprising: an oxidizing agent discharge channel for discharging an oxidizing agent from the oxidizing agent discharge channel; and means for detecting the concentration of vertical purple dioxide in the oxidizing agent discharging channel. h. The fuel according to claim 1, characterized in that the oxidizer discharge passage is provided with a control valve for adjusting the pressure of the oxidizer electrode, and the fuel electrode is also provided with pressure control means. Battery device t. 3. The fuel cell device according to claim 1, wherein the control valve and the pressure control means respectively control the pressure difference between the oxidizer electrode, the fuel electrode, and the inside of the container.