JPS6321201A - Reforming device for fuel battery - Google Patents

Abstract

PURPOSE:To uniformize the temp. distribution of a catalyst bed in a reaction tube and to permit steam reforming reaction with high reaction efficiency by forming the catalyst bed to the cross sectional area smaller toward the upper side. CONSTITUTION:A burner 2 as a heater is provided in the lower part of an evaporator 1 and the reaction tube 3 formed to a circular truncated cone shape is provided to the upper part of the evaporator 1 in a fuel reforming device for fuel batteries. The temp. of the heating gas generated from the burner 2 is absorbed in the mid-way of rising so that the temp. is lower toward the upper side in the process of the steam reforming reaction. On the other hand, the cross sectional area of the catalyst bed 4 in the reaction tube 3 changes larger toward the lower part and smaller toward the upper part; therefore, the heat is absorbed in a larger quantity, nearer the lower part. The heat is, therefore, balanced with the temp. distribution of the heating gas which is lower toward the upper part. The temp. distribution in the catalyst bed 4 is thus uniformized over the entire part in the vertical direction. The reaction efficiency is thus improved and the reformed gas contg. less impurities is generated according to the above-mentioned reforming device.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a fuel reformer for a fuel cell.

[Prior art]

A fuel cell consists of a reformer that converts fuel into hydrogen gas, and a fuel cell main body that reacts the hydrogen gas generated by the reformer with air (oxygen) and converts it into water and electricity.

In the reformer, fuel (for example, methanol and water) is vaporized by an evaporator, and then converted into hydrogen gas by carrying out a steam reforming reaction in a reaction tube having a catalyst layer.

By the way, the steam reforming reaction in the above-mentioned reformer is an endothermic reaction, and in order to perform this efficiently, it is desirable to make the temperature distribution of the catalyst layer as uniform as possible. This is because if the temperature distribution of this catalyst layer is non-uniform, the reaction efficiency will decrease and hydrogen gas containing many impurities will be likely to be generated.

[Purpose of the invention]

An object of the present invention is to provide a fuel cell reformer that eliminates the above-mentioned problems and enables a steam reforming reaction with high reaction efficiency by uniformizing the temperature distribution of the catalyst layer. be.

[Structure of the invention]

The reformer of the present invention that achieves the above object has a heater disposed at the bottom of the evaporator, a reaction tube filled with a catalyst layer for reacting the fuel vaporized in the evaporator at the top, and a heater. A fuel cell reformer in which heated gas is passed upward from the lower part of the outer wall surface of the reaction tube, characterized in that the cross-sectional area of the catalyst layer in the reaction tube is made smaller as it goes upward. .

〔Example〕

1 and 2 show a fuel cell reformer according to an embodiment of the present invention, in which 1 is an evaporator for vaporizing fuel;
A plurality of fuel supply pipes 7 degrees are attached around the periphery to discharge a liquid fuel mixture of methanol and water to the inside.

A burner 2 is provided at the bottom of the evaporator 1 as a heater,
Further, a reaction tube 3 formed in the shape of a truncated cone is provided at the upper part.

The reaction tube 3 is filled with a catalyst layer 4 formed of a pellet-shaped catalyst such as platinum, rhodium, or copper. Since the reaction tube 3 has a truncated conical shape as described above, the cross-sectional area of the catalyst layer 4 gradually becomes smaller as it goes upward. Further, a reaction gas collection chamber 6 is provided in the upper part of the reaction tube 3, in which hydrogen gas generated in the catalyst layer 4 is collected and then sent to the fuel cell main body (not shown).

A heated gas passage 5 passes vertically through the center of the evaporator 1, reaction tube 3, and gathering chamber 6, and heated gas generated by the burner 2 passes through the outer wall surfaces of the evaporator 1, reaction tube 3, and gathering chamber 6. It is designed to rise while heating. Further, the outer periphery of the evaporator 1, reaction tube 3, and collection chamber 6 is surrounded by a heat insulating wall 8 filled with a heat insulating material such as glass wool.

3 and 4 show other embodiments of the invention. In this embodiment, a plurality of reaction tubes 3 are arranged in a ring shape, and these plurality of reaction tubes 3. ~---------,
3 is a heating gas passage 5. In the case of this embodiment as well, the cross-sectional area of the catalyst layer 4 in each reaction tube 3 gradually becomes smaller as it goes upward, as in the above embodiment.

In such a reformer, the mixed liquid fuel dropped into the evaporator 1 from the fuel supply pipe 7 is immediately vaporized, and the vaporized fuel gas undergoes a steam reforming reaction in the catalyst layer 4 in the reaction tube 3. It changes into a reformed gas whose main component is hydrogen gas. The reformed gas is collected in the upper collecting chamber 6 and then sent to the fuel cell main body (not shown).

In the process of carrying out such a steam reforming reaction, the temperature of the heated gas generated from the burner 2 absorbs heat while rising, and thus decreases as it goes upward. On the other hand, the cross-sectional area of the catalyst layer 4 in the reaction tube 3 is larger at the bottom and decreases toward the top, so the lower part absorbs a large amount of heat. This is balanced with the temperature distribution of the heated gas, which decreases as it goes upward, and as a result, the temperature distribution within the catalyst layer 4 becomes uniform over the entire vertical direction. therefore,
The above reformer improves reaction efficiency and generates reformed gas with less impurities.

〔Effect of the invention〕

As described above, in the present invention, the cross-sectional area of the catalyst layer in the reaction tube in the fuel cell reformer becomes smaller as it goes upward, so that the amount of heat absorbed by the catalyst layer is balanced with the temperature change in the upward direction of the heated gas. However, since the temperature distribution of the catalyst layer becomes uniform throughout the vertical direction, a steam reforming reaction with high reaction efficiency can be carried out.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a reformer according to an embodiment of the present invention, FIG. 2 is a view taken along the nn arrow in FIG. 1, and FIG. 3 is a longitudinal cross-section of a reformer according to another embodiment of the present invention. Top view, Figure 4 is IV of Figure 3
-IV arrow view. ■...Evaporator, 2...Burner (heater), 3.
...Reaction tube, 4...Catalyst layer, 7...Fuel supply pipe.

Claims (1)

[Claims] A heater is placed at the bottom of the evaporator, and a reaction tube filled with a catalyst layer for reacting the fuel vaporized in the evaporator is placed at the top, and the heated gas from the heater is directed upward from the bottom of the outer wall of the reaction tube. A reformer for a fuel cell, characterized in that the cross-sectional area of the catalyst layer in the reaction tube becomes smaller as it goes upward.