JPH01320201A - Fuel reformer - Google Patents

Abstract

PURPOSE:To reduce the temp. difference in the radial direction of a catalyst bed and to increase the service life of a reaction tube by packing a reforming catalyst in a specified manner in the title reformer wherein the reaction tube packed with the catalyst is heated by a heating medium flowing along the side wall of the tube. CONSTITUTION:The granular reforming catalyst 5 is packed in a double tube consisting of the inner tube 3 and outer tube 4 arranged respectively inside and outside a partition cylinder 2 to form the reaction tube 1. The catalyst 5 is packed between the inner tube 3 and the cylinder 2 and between the cylinder 2 and the outer tube 4 to form the inner and outer catalyst beds 6 and 7, and both beds are connected to each other at the lower end. A burner 8 is set inside the inner tube 3, the outside of the reaction tube 1 is surrounded by a furnace vessel 9, and the combustion gas from the burner 8 is allowed to flow downward in the combustion chamber along the inner side face of the reaction tube 1, reversed at the lower end of the reaction tube 1, and allowed to flow upward along the outer side face of the reaction tube 1. In this reformer, the packing density of the catalyst 5 is progressively increased toward the side walls of the inner tube 3 and outer tube 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel reformer for reforming a reforming raw material gas into a hydrogen-rich gas under a reforming catalyst.

[Conventional technology]

Fuel cells directly convert chemical energy into electrical energy, and because they can achieve high thermal efficiency even with a small output, they have recently been developed and deployed as mobile power sources and remote island power sources to replace conventional engine generators and turbine generators. is in progress. By the way, as a hydrogen source for the fuel gas supplied to the fuel cell, natural gas, LPG, or methanol, which has a significantly lower reaction temperature than the hydrocarbons that are their main components, and which can be easily reformed, is used. ing. These hydrocarbons and methanol are reformed by a steam reforming reaction under a reforming catalyst into a gas rich in hydrogen, which becomes the fuel gas for the fuel cell. By the way, the main component of natural gas, methane, is reformed through the following two reactions.

CH, +) 1.0 → CO + 3H, −・−−−−−−
・−−−−〜−−f1+CO+H! O → CO, +l!
・−１１−−−・・−・・−・−・(2) The reaction of +11 is an endothermic reaction that takes place at 700°C to 900°C under the reforming catalyst of old yarn, and the reaction of (2) is an exothermic reaction carried out at 200°C to 400°C under a Cu-based reforming catalyst.

Note that the reaction (1) is carried out in a fuel reformer having a reaction tube filled with a Ni-based reforming catalyst, and the reaction (2) is carried out in a fuel reformer having a reaction tube filled with a Ni-based reforming catalyst.
This is carried out using a carbon monoxide shift converter containing a U-based reforming catalyst.

On the other hand, methanol is vaporized methanol gas as shown below.
It is thought that the property is modified by a stage reaction.

(JIsOH-hco + 2 H! -...-
−−1−−−−−・−−−−−−・・−(3) CO+H
1O→CO□+H!・－・・－－－－－－－－(4
1+31. The +41 reactions are all carried out at 200°C to 400°C under a Cu-based reforming catalyst, and the reaction (3) is an endothermic reaction, and the reaction (4) is an exothermic reaction, but in total it is an endothermic reaction. . In addition, in the reactions of (31 and (41), the reaction 1 degree is low and the -carbon oxide degree is also low, so fuel reforming!! that has a reaction tube filled with a Cu-based reforming catalyst can be carried out only with a device. .

The steam reforming reactions in the reaction tubes of the fuel reformer for reforming reforming raw material gases such as methane and methanol are all large endothermic reactions and therefore require heat to be supplied from the outside. In this way, as a fuel reformer that supplies heat from the outside and steam-reforms the reforming raw material gas, for example, the fourth
0, a reaction tube 1 is a double tube consisting of an inner tube 3 and an outer tube 4 disposed inside and outside a partition cylinder 2, in which a granular reformer is contained. The structure is filled with a quality catalyst 5. A reforming catalyst is filled between the inner tube 3 and the partition cylinder 2 and between the partition cylinder 2 and the outer tube 4 to form an inner catalyst layer 6 and an outer catalyst layer 7, which are connected at the lower end. ing.

The burner 8 is arranged inside the inner tube 3 of the reaction tube 1, and the burner 8 is arranged inside the inner tube 3 of the reaction tube 1.
surrounds the outside of the reaction tube l, and after the combustion gas from the burner 8 flows downward through the combustion chamber 11 along the inner surface of the reaction tube l,
After being turned back at the lower end of the reaction tube 1 and flowing upward through the fuel gas passage 12 along the outer surface of the reaction tube 1, it is discharged from the furnace vessel 9 through the discharge pipe 13 to the outside.

After heating the inner catalyst layer 6 in the front garden l, the outer catalyst layer 7 is heated and discharged from the furnace container 9 to the outside. When natural gas as the reforming raw material gas is introduced from the upper end of the inner tube side of the reaction tube 1, the natural gas flows from the heated inner catalyst layer 6 to the outer catalyst layer 7, and under the action of the reforming catalyst. The gas is reformed by steam reforming into a hydrogen-rich gas, and this reformed gas is sent out from the upper end of the outer tube side of the reaction tube 1 to the outside, for example, to a fuel cell.

[Problem to be solved by the invention]

As described above, the reaction tube I is heated by the heat medium flowing along the side wall, but since the thermal resistance between the reaction tube and the catalyst layer is large, a large temperature difference occurs in the temperature distribution in the radial direction of the reaction tube.

FIG. 4 is a graph showing the temperature distribution in the radial direction of a reaction tube uniformly filled with a reforming catalyst. From Figure 0, which shows the position of It is understood that the difference is large. If there is a temperature distribution with such a large temperature difference, the temperature of the outer wall of the reaction tube must be set at 1000°C in order to bring the average temperature of the catalyst layer to the specified temperature during the reforming reaction to obtain the specified amount of hydrogen gas. Such a high temperature, which must be raised above this level, has the disadvantage that it significantly accelerates the deterioration of the metal material constituting the reaction tube.

An object of the present invention is to develop a fuel reform '11 Vz that can delay the deterioration of the reaction tube and extend its life by reducing the temperature difference in the radial temperature distribution of the catalyst layer inside the reaction tube.
The goal is to provide a

[! Means to solve problem i]

In order to solve the above problems, according to the present invention, a reaction tube filled with a reforming catalyst is heated by a heat medium flowing along the side wall of the reaction tube, and the reforming raw material gas flowing through the reaction tube is converted into hydrogen. In a fuel reformer for reforming gas into a gas rich in fuel, the packing density of the reforming catalyst in the reaction tube is made higher as the position nearer to the side wall of the reaction tube increases in the direction perpendicular to the side wall of the reaction tube.

[Effect]

By making the packing density of the reforming catalyst layer filled in the reaction tube through which reforming raw material gas flows more dense in the direction perpendicular to the side wall of the reaction tube, that is, closer to the radial direction, the further from the side wall of the reaction tube The packing density of the reforming catalyst becomes lower, the thermal resistance becomes smaller, and the further away from the side wall the better the heat transfer performance becomes.
The temperature decrease rate in the radial direction becomes smaller, and the temperature difference in the temperature distribution becomes smaller accordingly.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view of a fuel reformer including a reaction tube filled with a reforming catalyst according to an embodiment of the present invention, and FIG. 2 is an enlarged view of section A in FIG. 1. Note that in Figures 1 and 2,
Components that are the same as those in the conventional example shown in the drawings are given the same reference numerals, and their explanations will be omitted. 1 and 2, the difference from the conventional example is that the inner catalyst layer 6 of the reaction tube 1. The granular particles in the outer catalyst layer 7 are made higher at positions closer to the side walls in a direction perpendicular to each side wall, that is, in a radial direction. That is, the second
As shown in the figure, the packing density is increased by adding finer reforming catalyst particles closer to the side wall of the inner tube.

Note that it is desirable to install panful plates 14 with a plurality of small holes 15 in multiple locations in the partition m2. This is because the packing density of the reforming catalyst on the partition cylinder side is lower than that on the side wall example of the inner tube 3. Since the flow resistance of the reformed raw material gas becomes smaller, the flow resistance is increased by the panful plate material, thereby making the flow resistance in the radial direction in the reaction tube uniform and making the amount of reformed raw material gas flow uniformly in the radial direction. It's for a reason.

FIG. 3 is a graph showing the temperature distribution in the radial direction of the reaction tube when natural gas as a reforming raw material gas is reformed into hydrogen-rich gas by heating the combustion gas from the burner with the above structure. It is understood from Figure 0, which is shown in the same way as Figure 5, that the 'tAK difference in the temperature distribution in the radial direction of the inner tube 6 of the reaction tube 1 is smaller than that of the conventional one, and the temperature is made uniform.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, by increasing the packing density of the reforming catalyst in the reaction tube at a position closer to the direction perpendicular to the side wall of the reaction tube along which the heat transfer medium flows, The packing density becomes lower, and as a result, the further away from the side wall the better the heat transfer performance and the smaller the temperature difference in the radial temperature distribution. In order to achieve this, it is not necessary to heat the side wall of the reaction tube to an excessively high temperature by means of a heat transfer medium. There is.

[Brief explanation of the drawing]

1 is a sectional view of a fuel reformer equipped with a reaction tube according to an embodiment of the present invention, FIG. 2 is an enlarged view of section A of the reaction tube in FIG. 1, and FIG. 3 is a fuel reformer in FIG. Fig. 5 is a cross-sectional view of a fuel reformer equipped with the fuel reformer shown in Fig. 4, in which the reforming raw material gas is reformed by the fuel reformer shown in Fig. 4. 1: reaction tube, 5: reforming catalyst, 8: burner .・-zu, Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1) A fuel reformer that heats a reaction tube filled with a reforming catalyst with a heat medium flowing along the side wall of the reaction tube to reform the reforming raw material gas flowing through the reaction tube into hydrogen-rich gas. A fuel reforming device characterized in that the packing density of the reforming catalyst in the reaction tube is increased at a position closer to the side wall of the reaction tube in a direction perpendicular to the side wall of the reaction tube.