JPH049198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel reformer, and more particularly to a catalyst tube for a fuel reformer that has a high overall heat transfer coefficient and can be designed compactly.

As a fuel reformer that performs a steam reforming reaction, a double-pipe catalyst tube as shown in FIG. 1 is known. In this system, a catalyst 3 is filled in the annular part of a double tube consisting of an outer tube 1 and an inner tube 2, and the reaction is carried out by heating from an external heat source.It has a more compact design than a single tube type. Although this is advantageous in that it is possible, according to the studies of the present inventors, there is still room for improvement as described below.

That is, an example of the measured temperature distribution in the radial direction within the catalyst layer 3 is shown in FIG. 2, and the gradient is still steep as shown by the solid line A in the figure, and this fact indicates that heat from an external heat source is This shows that the thermal resistance is large when transmitting the heat to the catalyst layer 3, and the heat transmission coefficient of the entire contact tube is also small. Note that numerals 1 to 3 in FIG. 2 mean the same parts as in FIG. 1.

An object of the present invention is to provide a fuel reformer that improves the conventional catalytic reaction tube described above, improves the overall heat transfer coefficient, and allows for a more compact design.

Here, the reason why the temperature distribution in FIG. 2 is as shown in A is because the thermal conductivity of the catalyst tube is insufficient compared to the chemical reactivity of the catalyst. In order to improve the thermal conductivity of the catalyst tube, the inventors of the present invention have conducted research to obtain a catalyst tube with a temperature distribution shown in B in FIG. They came up with the idea of increasing the overall heat transfer rate by inserting the heat exchanger, and arrived at the heating material reforming device of the present invention.

That is, the present invention provides a means for heating a double-tube type catalyst tube by an external heat source, and a means for heating a double-tube type catalyst tube by an external heat source, and a means for heating a double-tube type catalyst tube in the radial direction in a catalyst layer filled in an annular portion of the double-tube consisting of an outer tube and an inner tube. This is a heating material reforming device characterized by being provided with radial straight fins, spiral fins, or radial tip fins that promote heat conduction.

Here, the radial straight fin, spiral fin, and radial tip fin are made of a good thermal conductor, such as metal, as a heat conduction promoting material.

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

FIG. 3 is an explanatory diagram of an embodiment of the present invention,
In the figure, 1 is the outer cylinder of a double-pipe steam reforming reaction catalyst tube that has an external heating heat source, 2 is the inner cylinder, and 3 is the outer cylinder 1.
A radial straight fin is inserted between the fin 3 and the inner cylinder 2, 4 is an upper flange of the fin 3, 5 is a lower flange, and both 4 and 5 serve to support the fin. FIG. 4 is a sketch of this radial straight fin, and the upper and lower flanges 4 and 5 each have large openings for gas passage, and the lower flange 5 in particular has a perforated plate or wire mesh plate 6 for supporting the catalyst. is installed.

This device can accommodate any length of pipe by stacking any number of pipes in the axial direction of the pipe.

The heat given to the outside of the outer cylinder 1 from an external heat source is
In the catalyst layer 7 filled in the annular portion formed between the outer cylinder 1 and the inner cylinder 2, a steam reforming reaction is caused in the reaction gas passing therethrough. Since this reaction is an endothermic reaction, the conventional device shows a temperature distribution as shown in A in Figure 2, with a very large temperature gradient in the radial direction. This is because the heat conduction of the catalyst tube cannot keep up with the reaction.

In the device of the present invention, a radial fin 3 made of a good thermal conductor such as metal is installed and heat is quickly transferred in the radial direction, so a gentle temperature distribution (B in Figure 2) can be obtained. can. This means increasing the heat transfer coefficient of the catalyst tubes, thus allowing for a compact reformer design.

FIG. 5 is an explanatory diagram of another embodiment of the present invention,
Spiral fins 8 are used in place of the radial straight fins 3, and in addition to promoting heat conduction in the radial direction, a swirling flow is imparted to the reaction gas, resulting in a uniform temperature effect due to gas mixing. be.

Further, the embodiment of the present invention shown in FIG. 6 has a radial tip fin 9 attached to the inner cylinder 2 to produce the same effect.

Further, the embodiment of the present invention shown in FIGS. 7 and 8 is an application of the radial fin, in which the upper flange 10 and the lower flange 11 are sloped and the throat portion is formed in order to once completely collect and mix the radial gas flow. This is achieved by gas mixing and a temperature uniformity effect due to high flow rate when passing through 12.

Note that although the embodiments of the present invention have been described with reference to only the case of a double-pipe tube, it goes without saying that the present invention can also be applied to a single catalyst tube.

As is clear from the detailed description above, the effects of the fuel reformer of the present invention are as follows.

(1) Since a heat conduction promoting material is inserted into the catalyst layer, the overall heat transfer coefficient is improved.

(2) By providing a spiral fin, a radial tip fin, or a reaction gas mixing section, not only heat conduction is promoted but also a temperature uniformity effect is obtained, and the temperature distribution is further improved.

Therefore, the device of the present invention can be applied to fuel reforming devices for fuel cells and chemical plants, and has great effects, and is also economically advantageous because it allows for a more compact design.

[Brief explanation of drawings]

FIG. 1: An explanatory diagram of a conventional double-pipe catalyst tube for fuel reforming. Figure 2: A diagram showing temperature distribution within the catalyst layer.
The horizontal axis represents the distance from the center of the tube, and the vertical axis represents the temperature. FIG. 3: An explanatory diagram of one embodiment of the present invention. Figure 4: 3rd
A sketch of the radial straight fin shown in the figure. Fifth
Figure: Schematic diagram of a spiral fin in another embodiment of the present invention. FIG. 6: A sketch of a radial tip fin in yet another embodiment of the present invention. 7th
Figure: A diagram illustrating the application of a radial straight fin in another embodiment of the present invention. Figure 8: A sketch of the radial straight fin in Figure 7.

Claims (1)

[Claims] 1. A means for heating a double-tube type catalyst tube with an external heat source, and a means for promoting heat conduction in the radial direction in the catalyst layer filled in the annular part of the double-tube consisting of an outer tube and an inner tube. A fuel reforming device characterized by being provided with a radial straight fin, a spiral fin, or a radial tip fin.