JP2003109639A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system of high energy efficiency and high safety and having a reformer free from risk of deformation and fracture. SOLUTION: A heat supply method for reforming is improved by mounting a reformer in a combustion chamber for combusting an unused fuel and an unused oxidant from a fuel cell module. By improving an installation method of a reforming catalyst, the rapid progress of the reforming reaction at an inlet of a fuel passage of the reformer can be inhibited, and the generation of thermal stress caused by reforming can be also reduced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel cell system having a reformer.

[0002]

2. Description of the Related Art A fuel cell is a power generation element that supplies fuel to an anode and an oxidant to a cathode side and electrochemically reacts the fuel and the oxidant through an electrolyte to generate electricity. Typical raw fuels for fuel cells are city gas, methanol, gasoline, etc., and are suitable for power generation due to the reforming reaction that is a chemical reaction of hydrogen atoms and carbon atoms in raw fuels with water vapor and oxygen. It is generally supplied as a reformed gas containing hydrogen or carbon monoxide as a main component.

FIG. 6 shows an example of a conventional technique of a fuel cell system having a reformer. In the fuel cell module 3, the fuel reformed by the reformer 1 is directed to the anode side,
The oxidant is introduced to the cathode side, and the fuel and the oxidant electrochemically react with each other through the electrolyte to generate electricity. All of the introduced fuel and oxidant are not consumed in power generation, and unused fuel 5
And the unused oxidant 6 is discharged.

A typical example of reforming is steam reforming of city gas. The reforming reaction generally requires a temperature higher than 600 ° C. and is an endothermic reaction.
In the reformer 1, the fuel and the oxidant are supplied to the reforming burner 2 and the like to be burned, and the amount of heat necessary for the reforming is supplied.

[0005]

However, the conventional technique shown in FIG. 6 has a problem that the energy efficiency of the system is low because the fuel is consumed except for the power generation reaction. Further, the reformer has a problem that a large temperature distribution is likely to occur due to the reaction heat of the reforming, which causes deformation and sometimes damage due to thermal stress. When flammable gas flows out due to deformation and damage of the reformer, not only the power generation efficiency is lowered, but also there is a risk of explosion or the like.

In view of the above problems of the prior art, the present invention can effectively utilize the unused fuel and the unused oxidizer from the fuel cell to reform the fuel, and there is a risk of deformation and damage. An object of the present invention is to provide a fuel cell system having a reformer with less fuel consumption.

[0007]

In order to solve the above problems, the first invention provides a fuel cell system having a reformer in which a reformer is installed in a combustion chamber. The combustion gas generated in the combustion chamber is used as a heat source for reforming, and the thermal energy of the unused fuel and the unused oxidant is effectively used.

According to the second aspect of the invention, the reforming catalyst installed in the fuel passage of the reformer has a low activity near the fuel inlet of the catalyst installation range and a high activity near the fuel outlet. Provide a fuel cell system. By doing this,
It suppresses the rapid progress of the reforming reaction at the fuel flow path inlet of the reformer, and reduces the generation of thermal stress.

Further, according to the third aspect of the invention, the catalyst installation position of the reforming catalyst installed in the fuel passage of the reformer is discontinuous in the fuel flow direction, and the space where the catalyst is not installed is defined as the fuel outlet. Provided is a fuel cell system including a reformer which is enlarged from the inlet to the inlet. By doing so, it is possible to prevent the reforming reaction from rapidly advancing at the fuel flow path inlet of the reformer and reduce the generation of thermal stress.

Further, in the fourth aspect of the invention, when the fuel passages of the reformer are a plurality of passages parallel to each other, the installation positions of the reforming catalyst in the fuel flow direction are in a neighborhood relationship. Provided is a fuel cell system including a reformer in which a reforming catalyst is arranged with a gap so as not to be in the same position between them.
By doing so, the locations where the reforming reaction occurs are dispersed between the flow paths, and the generation of thermal stress is not concentrated.

The fifth aspect of the present invention provides a fuel cell system including a reformer in which the type of fuel cell is a molten carbonate fuel cell or a solid oxide fuel cell having a high operating temperature. The fuel cell is a molten carbonate fuel cell or a solid oxide fuel cell, and by raising the temperature of the combustion gas, the speed of the reforming reaction is improved, and the amount of required reforming catalyst is small and compact reforming is performed. It can be a bowl.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an example of a configuration diagram of a fuel cell system having a reformer according to the present invention. The fuel cell module 3 is an assembly in which a plurality of fuel cell elements each having an anode and a cathode on both sides of an electrolyte are connected to each other. The fuel is supplied to the anode and the oxidant is supplied to the cathode, and the fuel and the oxidant are electrically supplied via the electrolyte. Reacts chemically to generate electricity. The unused fuel 5 and the unused oxidant 6 which have not been consumed in the power generation burn in the combustion chamber 4 adjacent to the fuel cell module 3 and reform the fuel in the combustion chamber reformer 7 installed in the combustion chamber 4. It becomes a heat source for. With the above-described configuration, the heat energy of the unused fuel 5 and the unused oxidant 6 can be used as a heat source for reforming without loss, so that the efficiency is higher than that of the conventional technology. Fuel cell system.

City gas, methanol, gasoline or the like can be used as the fuel, and air is generally used as the oxidizer.

FIG. 2 shows an example of a reformer according to the present invention, and FIGS. 2 (a), 2 (b) and 2 (c) are front and side views of the combustion chamber reformer 7, respectively. FIG. 4 is an external view of the upper surface, and the reforming catalyst 20 is installed in the fuel flow path 21 of the plate fin type heat exchanger. The combustion gas obtained by burning the unused fuel and the unused oxidant passes through the combustion gas flow path 22, and the fuel passes through the fuel flow path 21, and the thermal energy of the combustion gas is used as the heat source for reforming. In addition, the reformer produces a temperature distribution due to the reaction heat associated with the reforming reaction, and the thermal stress causes deformation of the reformer,
It is easily damaged. In order to reduce the thermal stress, it is necessary to control the reforming reaction. In the reformer according to the present invention, the reforming catalyst is installed as shown in FIGS. 3, 4 and 5. .

FIG. 3 is an example of installation of a reforming catalyst, and is a view of a cross section A of the combustion chamber reformer 7 in FIG. 2 as viewed from above. The reforming catalyst 20 installed in the fuel flow path 21 has a catalyst with low activity near the fuel inlet and a catalyst with high activity toward the outlet, which causes uneven reforming near the fuel inlet. Relieves thermal stress.

FIG. 4 shows an example of installing a reforming catalyst,
It is the figure which looked at the cross section A of the combustion chamber reformer 7 in FIG. 2 from the upper surface. By providing a portion where the reforming catalyst 20 is not installed in the fuel flow path 21 and further widening the portion where the catalyst is not installed near the fuel inlet and narrow near the fuel outlet,
It reduces the thermal stress due to reforming that occurs unevenly at the fuel inlet.

FIG. 5 shows an example of installing a reforming catalyst,
It is the figure which looked at the cross section A of the combustion chamber reformer 7 in FIG. 2 from the upper surface. By arranging the reforming catalyst 20 in the fuel flow passage 21 with a gap in the fuel flow direction, and by disposing the catalyst installation positions in adjacent fuel flow passages in the fuel flow direction not to be the same, Disperses the places where quality reactions occur and relaxes thermal stress.

In the embodiment of the present invention shown in FIGS. 2 to 5, the reformer is a plate fin type heat exchanger provided with a catalyst, which is a means for increasing the efficiency of heat supply for reforming. The same effect can be expected by other heat exchange means. For example, a reformer in which a fin for improving heat exchange efficiency is installed in a tube in which a reforming catalyst is installed may be considered. Further, in the fuel cell system of the present invention, a molten carbonate fuel cell or a solid oxide fuel cell in which the operating temperature is high and the unused fuel and the unused oxidant are also high in temperature is applied to the fuel cell system of the present invention. Thereby, it becomes possible to improve the reaction speed of reforming and downsize the reformer.

[0019]

As explained above, according to the fuel cell system of the present invention, the reformer is installed in the combustion chamber to effectively utilize the thermal energy of the unused fuel and the unused oxidant. It becomes possible to increase energy efficiency. Further, according to the fuel cell system of the present invention, different active catalysts are installed in the reformer, or the catalyst installation position is devised to reduce the thermal stress generated in the reformer and improve safety. A system having a high reformer can be obtained.

[Brief description of drawings]

FIG. 1 is an example of a fuel cell system having a reformer according to the present invention.

FIG. 2 shows an example of a reformer according to the present invention.

FIG. 3 is an example of installing a catalyst in a reformer according to the present invention.

FIG. 4 is an example of installing a catalyst in a reformer according to the present invention.

FIG. 5 shows an example of installing a catalyst in the reformer according to the present invention.

FIG. 6 shows an example of a fuel cell system having a conventional reformer.

[Explanation of symbols]

1: reformer 2: reforming burner 3: Fuel cell module 4: Combustion chamber 5: Unused fuel 6: Unused oxidizer 7: Combustion chamber reformer 20: Reforming catalyst 21: Fuel flow path 22: Combustion gas flow path

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiro Kuroishi             2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             No. Totoki Equipment Co., Ltd. (72) Inventor Satoshi Matsuoka             2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             No. Totoki Equipment Co., Ltd. (72) Inventor Toshiya Abe             2-1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture             No. Totoki Equipment Co., Ltd. F-term (reference) 4G040 EA02 EA03 EA06 EB44 EC07                 5H026 AA05 AA06                 5H027 AA05 AA06 BA09 BA10

Claims (5)

[Claims] 1. A fuel cell module in which a plurality of fuel cells having an anode and a cathode on both sides of an electrolyte are joined together,
An oxidant supply means for supplying an oxidant to the fuel cell module, a fuel supply means for supplying a reformable fuel to the fuel cell module, and a fuel supplied from the fuel supply means for reforming the fuel. A fuel cell system including a reformer having a reforming catalyst for supplying reformed gas to a cell module, and a combustion chamber for burning unused fuel and unused oxidant discharged from the fuel cell module. A fuel cell system, wherein the reformer is installed in the combustion chamber. 2. The activity of the reforming catalyst installed in the fuel passage of the former reformer is low near the fuel inlet of the catalyst installation range,
The fuel cell system according to claim 1, wherein the fuel cell system is high near the fuel outlet. 3. The catalyst installation position of the reforming catalyst installed in the fuel passage of the former reformer is discontinuous in the fuel flow direction, and the space where the catalyst is not installed is from the fuel inlet to the outlet. The fuel cell system according to claim 1, wherein the fuel cell system is reduced in size as it goes. 4. The fuel passages of the former reformer are a plurality of passages that are parallel to each other, and the installation positions of the reforming catalysts in the fuel flow direction are the same in the neighboring fuel passages. The fuel cell system according to claim 1, wherein the reforming catalyst is arranged so as to have a void so as not to occur. 5. The fuel cell system according to any one of claims 1 to 4, wherein the fuel cell is a molten carbonate fuel cell or a solid oxide fuel cell.