JPS6269470A - Internal-reformation fuel cell - Google Patents

Abstract

PURPOSE:To very easily and uniformly transfer heat between the place of heat generation in electrochemical reaction and that of heat absorption in reforming reaction, increase the production of reformed gas, simplify the construction of an internal-reformation fuel cell and make it compact, by directly reforming fuel in a fuel electrode also serving as a fuel reforming catalyst. CONSTITUTION:A fuel electrode 2-a, an oxidizer electrode 3-a facing the fuel electrode across an electrolyte matrix 1, fuel passages 9 defined by ribs located in contact with the fuel electrode, oxidizer passages 6 defined by ribs located in contact with the oxidizer electrode, and separators 4-a defining the fuel passages and the oxidizer passages together with the ribs are provided. Fuel is directly reformed in the fuel electrode 2-a also serving as a fuel reforming catalyst 10. As a result, heat is very easily and uniformly transferred between the place of heat absorption in reforming reaction and that of heat generation in electrochemical reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an internal reforming fuel cell that generates power while reforming a fuel such as hydrocarbon inside the cell.

[Conventional technology]

Conventionally, as an internal reforming type fuel cell, for example,
An internal reforming fuel cell described in Japanese Patent No. 32255 is known. The conventional internal reforming fuel cell described above will be explained below with reference to FIG. In Figure 3,
1 is an electrolyte matrix composed of porous ceramics and its voids are impregnated with carbonate, 2 is a fuel electrode composed of porous nickel, etc., and 3 is an oxide matrix composed of porous nickel oxide, etc. The agent electrode, the fuel electrode 2, and the oxidizer electrode 3 are arranged so as to face each other with an electrolyte matrix 1 interposed therebetween, and these constitute a single cell. 4 is a separator that separates fuel gas and oxidizing gas;
5 ribs are provided. An oxidant passage 6 is formed between the oxidant electrode 3 and the ribbed separator 4. Reference numeral 7 denotes a fuel side spacer which is provided in contact with the fuel electrode 2, has many holes for fuel passage, and is provided with ribs 8. Fuel side spacer 7 and Nanano'? A fuel passage 9 is formed between the lakes 4. 10 is a fuel reforming catalyst filled in the fuel passage 9. As described above, an internal reforming fuel cell is constructed.

In the internal reforming fuel cell having the above configuration, when fuel such as a hydrocarbon and steam are supplied to the fuel passage 9, the hydrocarbon reacts with the steam due to a catalytic reaction of the fuel reforming catalyst 10, Hydrogen, - converted to carbon oxide and carbon dioxide. When the hydrocarbon is methane, this reaction is expressed by the following formula, and the composition of hydrogen, carbon oxide, carbon dioxide, and methane is an equilibrium value determined by the reaction conditions.

CH4+H20oCO+3H2 H20+CO2CO2+H2 The generated hydrogen and carbon monoxide pass through the holes provided in the fuel side spacer 7 and diffuse within the pores of the porous fuel electrode 2. On the other hand, air and carbon dioxide are supplied to the oxidant passage 6 and diffused within the pores of the porous oxidant electrode 3 . Impregnated with electrolyte matrix, cell operating temperature 650℃
Nearby, the reactive gas is consumed by an electrochemical reaction between the molten carbonate, electrode 2.3, and the hydrogen and carbon monoxide mentioned above, and oxygen, and a potential is generated between electrodes 2 and 3, causing an electric potential to flow outside. It is extracted as electricity.

The reforming reaction that occurs on the fuel reforming catalyst is an endothermic reaction, and the amount of heat required to sustain the reaction is due to the heat generated by the irreversible reaction accompanying the electrochemical reaction. The fuel is supplied to the fuel reforming catalyst 10 via I-. In this way, by combining exothermic and endothermic reactions in the cell, heat transfer can be carried out efficiently, and therefore, the internal reforming fuel cell is characterized by high thermal efficiency and high power generation efficiency.

However, inside a single cell, the electrolyte matrix and the vicinity of the electrodes generate heat due to electrochemical reactions, resulting in high temperatures, whereas the temperature in the fuel reforming catalyst decreases due to an endothermic reforming reaction. Become. This results in heat transfer from the electrolyte matrix towards the fuel reforming catalyst. However, since fuel gas such as hydrocarbon is converted into hydrogen or carbon monoxide on a fuel reforming catalyst and then transferred to a fuel electrode to generate electricity, the movement of gas (substance) is in the opposite direction to the movement of heat. In other words, heat transfer is less likely to occur than when heat transfer and mass transfer occur in the same direction.

Also, after reforming of a fuel gas, such as a hydrocarbon, to hydrogen and carbon monoxide occurs on a fuel reforming catalyst, consumption of the hydrogen and carbon monoxide occurs on the fuel electrode. That is, since the production and consumption of hydrogen and carbon monoxide do not occur simultaneously, there is a limit that the amount of hydrogen and carbon monoxide produced cannot exceed the amount determined by chemical equilibrium.

In addition, conventional internal reforming fuel cells require a fuel reforming catalyst and a spacer on the fuel side, making it difficult to make the cell thin. In addition, fuel reforming catalysts require the process of crushing, sizing, and filling existing pellet- or tablet-shaped catalysts for hydrogen production, and it is also necessary to pay attention to uniform filling during power generation operation. Ta.

The above is described in the above-mentioned Japanese Patent Application Laid-Open No. 60-32255,
What has been disclosed as the prior art has been described, and the invention described in the publication relates to an improvement on the above prior art. By enlarging the cross-sectional area perpendicular to the flow direction of the fuel toward the flow direction of the fuel, the fuel reforming reaction is made uniform in the flow direction of the fuel, and the temperature distribution within the cell is thereby made uniform. However, although similar techniques are briefly described as falling within the scope of the invention, they do not solve the basic problems of the prior art described above, and furthermore, the structure is There are drawbacks that make it even more complex.

[Purpose of the invention]

An object of the present invention is to provide an internal reforming fuel cell in which the above-mentioned drawbacks of conventional internal reforming fuel cells are simultaneously eliminated.

The first object of the present invention is to provide an internal reforming fuel cell in which heat transfer between the heat generated by the electrochemical reaction and the heat absorbed by the reforming reaction is carried out extremely easily and evenly. It is something.

Second, the present invention provides an internally reformed fuel that increases the amount of gas produced by reforming compared to the case where the reformed gas is maintained in an equilibrium state under reforming reaction conditions after it is generated, and has high power generation efficiency. The purpose is to provide batteries.

Thirdly, the present invention provides an internal reforming fuel cell which has a simple structure, can be easily manufactured in a short time, and can be downsized especially when used in a stacked manner. The purpose is to provide

[Technical means to achieve the purpose]

That is, the present invention provides an internal reforming fuel cell in which a fuel electrode and an oxidizer electrode are arranged to face each other with an electrolyte matrix interposed therebetween, in which fuel is directly reformed within the fuel electrode that also serves as a fuel reforming catalyst. The present invention provides an internal reforming fuel cell characterized by:

More specifically, the present invention provides a fuel electrode, an oxidizer electrode disposed to face the fuel electrode with an electrolyte matrix in between, a fuel passage formed by a rib in contact with the fuel electrode, and a fuel passageway in contact with the oxidizer electrode. The oxidizer passages formed by the ribs, and the oxidizer passages that form the fuel passages and the oxidizer passages together with the ribs, allow the fuel to be directly reformed in the fuel electrode that also serves as a fuel reforming catalyst. The present invention provides an internal reforming fuel cell characterized by:

The fuel electrode used in the present invention is not particularly limited as long as the reforming reaction can be carried out within the electrode, and it may be a conventionally known fuel electrode, for example, a flat plate-shaped fuel electrode made of porous nickel, nickel and chromium. Porous electrodes are preferred, and those with a large surface area are particularly preferred from the viewpoint of catalytic action.

The fuel applied to the internal reforming fuel cell of the present invention is a hydrocarbon such as methane.

Oxidizer electrode used in the internal reforming fuel cell of the present invention,
As the electrolyte matrix and the like, there are no particular limitations, and conventionally known ones can be used.

The separator in the internal reforming fuel cell of the present invention has ribs on both sides, one rib in contact with the fuel electrode forms a fuel passage, and the other rib in contact with the oxidizer electrode forms a fuel passage. A fuel passage is formed in the fuel electrode, or a fuel passage is formed in a planar shape with one side in contact with the fuel electrode and a rib formed integrally with the fuel electrode,
Oxidant! It is preferable to have a structure in which an oxidizing agent passage is formed by the other surface in contact with @ and a rib formed integrally with the oxidizing agent electrode.

The internal reforming fuel cell of the present invention includes the fuel electrode, the oxidizer electrode arranged to face the fuel electrode via an electrolyte matrix, the fuel passage, the oxidizer passage, and the separator. It is suitable for use by laminating two slender structural units.

〔Example〕

The present invention will be explained in more detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram for illustrating an example of the first embodiment of the internal reforming fuel cell of the present invention. In FIG. 1, 1 is an electrolyte matrix composed of porous ceramics whose voids are impregnated with carbonate; 17.
2-a is a flat fuel electrode made of porous nickel, etc.; 3-a is a flat oxidizer electrode made of porous nickel oxide, etc.; It is arranged to face the agent electrode 3-a with the electrolyte matrix 1 interposed therebetween. 4-a has a rib 11 and an oxidizer electrode 3-a on both sides of which are in contact with the fuel electrode 2-a, respectively.
A seven-point Plator having ribs 5 in contact with each other, a fuel passage 9 is formed between the rib 11 and the surface of the fuel electrode 2-a with which it contacts, and a fuel passage 9 is formed between the rib 5 and the surface of the fuel electrode 2-a with which it contacts. An oxidizing agent passage 6 is formed with the surface 3-a. In this way, the internal reforming fuel cell according to the first embodiment of the present invention is constructed.

FIG. 2 is an explanatory schematic diagram showing an example of the second embodiment of the internal reforming fuel cell of the present invention.

In FIG. 2, 1 is an electrolyte matrix made of porous ceramics whose voids are impregnated with carbonate, and 2-b is an integrally formed rib 13 made of porous nickel, etc. It is a fuel electrode having 3-
b is an oxidizer electrode made of porous nickel oxide or the like and has integrally formed ribs 12;
The oxidizer electrode 3-b and the electrolyte electrode 3-b are arranged to face each other via an IJ hook. 4-b is a flat plate-like lattice plate, which is connected to the rib 13 and the rib 13.
A fuel passage 9 is formed by one surface of the separator 4-b that is in contact with the rib 12, and an oxidizer passage 6 is formed by the rib 12 and the other surface of the separator 4-b that is in contact with the rib 12. In this way, the internal reforming fuel cell according to the second embodiment of the present invention is constructed.

A first embodiment showing the first and second embodiments of the present invention described above.
The operation of the internal reforming fuel cell of the present invention will be explained below with reference to the drawings and FIG. In FIG. 1 or 2, fuel such as hydrocarbon and water vapor are directly supplied to the fuel electrode 2-a or 2-b from the fuel passage 9, and a reforming reaction of the fuel occurs within the porous fuel electrode. Immediately, a fuel such as a hydrocarbon reacts with water vapor to produce hydrogen, carbon oxides and carbon dioxide. The hydrogen and carbon monoxide thus produced react electrochemically with the ions of the electrolyte matrix in the fuel electrode at the same time as they are produced, and are immediately consumed. Since the production and consumption of this reformed gas occur simultaneously and over substantially the entire area within the fuel electrode, heat transfer between the heat absorption due to the reforming reaction and the heat generated due to the electrochemical reaction is extremely easy and uniform. Moreover, according to the principle of shifting chemical equilibrium, a much larger amount of reformed gas, i.e., hydrogen and monoxide Carbon is produced and used to generate electricity.

〔Effect of the invention〕

According to the present invention, firstly, the reforming reaction and the electrochemical reaction are performed simultaneously within the fuel electrode, so heat transfer between the heat absorption accompanying the reforming reaction and the heat generation accompanying the electrochemical reaction is extremely easy. , and an internal reforming fuel cell in which the reforming reaction is carried out evenly.Secondly, the reforming reaction produces gas and consumes it through an electrochemical reaction at the same time as it is produced. An internal reforming fuel cell that increases the amount of reformed gas produced and has high power generation efficiency compared to the case where the reformed gas is maintained in a chemical equilibrium state, and thirdly, this technology is used as a fuel reforming catalyst separate from the fuel electrode. Breaking away from conventional ideas in the field, it is possible to omit the fuel reforming catalyst and fuel side spacer, which were required in conventional internal reforming fuel cells, resulting in a simple structure that is quick and easy. The present invention provides an internal reforming fuel cell that can be manufactured in a number of ways, and that can be downsized, especially when used in a stacked manner.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining an example of a first embodiment of an internal reforming fuel cell of the present invention. Figure 2 shows
FIG. 3 is a schematic diagram for explaining an example of a second embodiment of the internal reforming fuel cell of the present invention. FIG. 3 is a schematic diagram for explaining a conventional internal reforming fuel cell. In Figures 1 to 3: 1... Electrolyte matrix; 2, 2-a, 2-b...
・Fuel electrode: 3, 3-a, 3-b... Oxidizer electrode: 4
, 4-a, 4-b-... Separator: 5
, 8, 11. 12.13... Rib; 6... Oxidizer passage; 7...
Fuel side cover; 9...Fuel passage; 10...Fuel reforming catalyst.

Claims (1)

[Claims] 1. In an internal reforming fuel cell in which a fuel electrode and an oxidizer electrode are arranged to face each other via an electrolyte matrix, the fuel is directly reformed within the fuel electrode which also serves as a fuel reforming catalyst. Features an internal reforming fuel cell.