JPH0397601A - Fuel reformer - Google Patents

Abstract

PURPOSE:To obtain the fuel reformer capable of uniformly heating a reforming tube with combustion gas by providing a burner cylinder hung from the periphery of a burner and a combustion cylinder erected from the bottom of a furnace vessel, forming a heating medium passage with the lower part of the burner cylinder and enclosing the cylinder. CONSTITUTION:A flame and combustion gas are produced by the combustion in a burner 2, the flame is extended downward in a burner cylinder 21, reversed at its lower end into a combustion gas passage 23 and passed through the passage 23 to cause complete combustion, but the flame is not extended to the outside of the passage 23. Accordingly, only the combustion gas is discharged from the passage 23, reversed at the upper end of the combustion cylinder 22, passed between the cylinder 22 and a partition wall 4 and introduced into a heating chamber 10. Consequently, the combustion gas is uniformly distributed into the heating chamber 10, a catalyst bed 14 in the reforming tube 13 arranged in the chamber 10 is not overheated by the flame, the catalyst bed 14 is uniformly heated by the combustion gas uniformly introduced into the bed 14, and the temp. in the circumferential direction is uniformly distributed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel reformer that is incorporated into a fuel cell power generation system to reform a reformed raw material gas into hydrogen-rich gas and supply the same to a fuel cell. [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 used as mobile power sources to replace conventional engine generators and turbine generators, and for use on remote islands. Developed as a power source. Deployment is underway. By the way, methanol is used as a hydrogen source for the fuel gas supplied to fuel cells, as it has a much lower reaction temperature than natural gas, LPG, or the hydrocarbons that are their main ingredients, and the reforming process is simple. There is. These hydrocarbons and methanol are reformed into hydrogen-rich gas by a steam reforming reaction under a reforming catalyst, which becomes the fuel gas for the fuel cell. By the way, methane, which is the main ingredient in natural gas, is reformed through the following two reactions. CHa +HjO→CO+3H mushroom...one...
...(1) Co +H, O→Cow +Ht
・・・1・・・・・・《2》(The reaction in 1 is an endothermic reaction that is carried out at 700 to 900 °C under an Nl-based reforming catalyst, and the reaction in (2) is an endothermic reaction that is carried out under a Nl-based reforming catalyst. under the reforming catalyst of 200
It is an exothermic reaction that takes place between ℃ and 400℃. Furthermore, (1)
The reaction (2) is carried out in a fuel reformer with a reforming tube filled with an old reforming catalyst, and the reaction (2) is carried out in a carbon monoxide transformer containing a Cu-based reforming catalyst. It will happen. On the other hand, methanol is vaporized methanol gas as shown below.
It is thought that the modification occurs through stage reactions. ? H x O H = C O + 2 H *
・・・−・・・−・・・−・・・(3)C O +H
* O→CO■10H, ・(4)+31,
All +41 reactions were conducted at 200% under Cu-based reforming catalyst.
The reaction (3) is an endothermic reaction, and the reaction (4
The reaction J is an exothermic reaction, but overall it is an endothermic reaction. Note that the reactions (3) and (4) are performed only in a fuel reformer having a reforming tube filled with a Cu-based reforming catalyst because the reaction temperature is low and the concentration of carbon monoxide is low. The steam reforming reaction in the reforming tube of the fuel reformer that reformes the reforming raw material gas such as methane and methanol is a large endothermic reaction, so it is necessary to supply heat from the outside. The key point is heat transfer from the outside. Heat is supplied from the outside using a high-temperature heat medium, such as combustion gas, and a reforming tube filled with a reforming catalyst is placed inside the fuel reformer container, and the combustion gas is guided into the container. A stream is passed along the wall of the reforming tube to heat the catalyst layer consisting of the reforming catalyst inside the reforming tube, and the reforming raw material gas is reformed into hydrogen-rich gas through a steam reforming reaction. The combustion gas transfers its own heat to the reformed raw fuel gas through heat transfer, resulting in a significant drop in temperature. For this reason, it is difficult to ensure a uniform amount of heat transfer upstream and downstream of the catalyst layer, and as a means to correct this, proposals have been made, for example, to attach heat transfer fins as a heat transfer promoting means to the outer wall of the reforming tube. The one shown in Figure 2 is conventionally known as such a fuel reformer. In the figure, 1 is a furnace vessel of a fuel reformer, which is equipped with a burner 2 at the center of the upper part, and a cylindrical partition wall 4 lined with a refractory 3 is suspended surrounding the burner 2. The burner 2 is provided with an inlet pipe 5 for combustion fuel and a combustion gas reservoir (not shown), and a combustion gas outlet 7 is provided in the upper part of the furnace vessel 1. The combustion chamber 8 inside the partition wall 4 is provided with a spiral heating tube 9 for superheating the reformed raw material gas, and the annulus-shaped heating chamber 10 between the partition wall 4 and the furnace vessel l is provided with a partition wall 4. A reforming pipe 13 consisting of an inner cylinder 11 and an outer cylinder 12 surrounding the cylinder is disposed. The reforming pipework 3 is filled with a reforming catalyst to form a catalyst layer l4, and fins 15 for promoting heat transfer are attached to the outer wall of the reforming pipe 13 from the middle to the upper circumference. There is. In addition, at the upper end of the superheating tube 9, there is a reforming raw material gas inlet pipe 1 that passes through the upper plate of the furnace vessel 1.
6, and a connecting pipe 17 connected to the lower end of the reforming pipe 13 is attached to its lower end, and a connecting pipe 17 connected to the lower end of the reforming pipe 13 is attached to the upper end of the reforming pipe 13.
A reformed gas outlet pipe 18 is attached that passes through the upper plate of the pump. With this structure, combustion fuel is supplied to the burner 2 through the combustion fuel inlet pipe 5, and combustion air is supplied to the burner 2 through the inlet pipe (not shown), so that the combustion fuel is combusted. The flame and combustion gas generated by this combustion heat up the superheater 9 in which the combustion chamber 8 is disposed, and the combustion gas flows further downward, makes a U-turn around the lower end of the partition wall 4, and flows upward through the heating chamber 10. , heating chamber l
The reforming tube l3 disposed at the fin 15 is heated, heat transfer is promoted by the fins 15, and the catalyst layer 14 is heated to raise its temperature. The combustion gas, which has become low temperature due to heat transfer, is discharged to the outside from the combustion gas outlet 7. On the other hand, when the temperature of the catalyst layer 14 reaches a predetermined value, the reforming material gas is supplied to the heat exchanger g9 through the reforming material gas inlet pipe 16. The reforming raw material gas supplied to the superheating tube 9 is heated by the flame and combustion gas to become superheated gas, and this superheated gas flows into the reforming tube l3 via the connecting pipe 17. The inflowing superheated gas flows upward through the catalyst layer 14 in the reforming tube l3, during which time it is heated by the combustion gas flowing along the outer wall of the reforming tube 13, and heat transfer is promoted by the fins 15, so that heat is transferred to the catalyst layer 14. is given, and the reforming raw material gas undergoes steam reforming under a catalyst at the reforming reaction temperature. This reformed gas is supplied to the fuel cell. [L [Problem to be Solved by the Invention] In order to steam reform the reforming raw material gas in the fuel reformer, combustion is performed in the burner 2 and the catalyst layer 14 in the reforming tube 13 is heated. However, during combustion, the flame generated in the combustion chamber 8 may extend long enough to turn around the lower end of the partition wall 4 and enter the heating chamber 10. Therefore, the flame that entered the catalyst layer
4 is overheated, the catalyst deteriorates, and the temperature distribution in the circumferential direction of the catalyst layer 14 becomes uneven due to the gradient of the flow rate of the combustion gas flowing through the heating chamber 10. An object of the present invention is to provide a fuel reformer in which the flame from the burner does not directly heat the reforming tube, but the combustion gas evenly heats the reforming tube. (Means for solving ! IIm) In order to solve the above problems, the present invention includes a burner provided at the center of the upper part of the furnace vessel, and a cylindrical partition wall surrounding the burner and suspended from the upper part of the furnace vessel. and a reforming tube filled with a reforming catalyst placed between the partition wall and the side wall of the furnace vessel to surround the partition wall, and the reforming tube is heated by a heat medium generated by combustion from a burner to perform reforming. In a fuel reformer for reforming reforming raw material gas flowing through a pipe, there is a burner tube suspended from around the burner within the partition wall, and a burner tube that stands upright from the bottom of the furnace vessel and extends from the lower end of the burner tube. [Operation] The flame burned in the burner extends long inside the burner cylinder and enters the heat medium passage formed by the burner cylinder and the combustion cylinder. but,
Complete combustion occurs while passing through this heating medium passage, and the flame does not extend outside the heating medium passage and does not enter the reforming tube between the partition wall and the furnace vessel, so the reforming catalyst is overheated. does not occur. In addition, the combustion gas leaving the combustion tube is evenly distributed to the reforming tubes surrounding the partition wall, regardless of the angle of the flame, and the reforming tubes are heated evenly. [Examples] Examples of the present invention will be described below based on the drawings.
FIG. 1 is a sectional view of a fuel reformer according to an embodiment of the present invention. In Fig. 1, parts that are the same as those in the conventional example shown in Fig. 2 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, the difference from the conventional example is that the burner f! is suspended from around the burner 2 in the positive wall 4! J21 and a cylindrical combustion flJ22 that stands upright at the bottom of the furnace vessel 1 and surrounds a part of the burner cylinder 2l from the lower end. Note that a combustion gas passage 23 is formed between the burner cylinder 2l and the combustion cylinder 22. Further, the superheating pipe 9 is arranged in the combustion gas passage 23. With this structure, flame and combustion gas are generated by combustion in the burner 2, but even if the flame extends long and turns its lower end from the burner 1m21 and enters the combustion gas passage 23, complete combustion will not occur while passing through the combustion gas passage 23. is carried out, and the flame does not extend outside the combustion gas passage 23. Therefore, only the combustion gas is discharged from the combustion gas passage 23, turns around at the upper end of the combustion tube 22, flows between the combustion tube 22 and the partition wall 4, and flows into the heating chamber 10, so that the combustion gas is evenly distributed in the heating chamber 10. It will be done. Therefore, the catalyst layer 14 in the reforming tube 13 arranged in the heating chamber IO is not heated by the flame, and the catalyst layer 14 is evenly heated by the evenly distributed combustion gas, so that the temperature distribution in the circumferential direction is uniform. will be converted into [Effects of the Invention] As is clear from the above description, according to the present invention, there is a burner tube suspended from the periphery of the burner, a burner tube that stands upright from the bottom of the furnace vessel, and a part of the burner tube from the lower end is used as a heat medium. By providing a combustion tube that forms and surrounds a passage, even if the flame extends long due to combustion in the burner, the flame does not extend outside the combustion gas passage, and only combustion gas is discharged from the combustion gas passage. The reforming tube is not directly heated by the flame, but is heated by the evenly distributed combustion gas, which prevents deterioration of the catalyst and equalizes the temperature distribution in the circumferential direction of the catalyst layer.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a fuel reformer according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional fuel reformer. 1; Furnace vessel,
4: Partition wall, 13: Reforming pipe, 14: Catalyst layer, 21: Burner cylinder, 22: Combustion cylinder, 23: Combustion gas passage-4

Claims (1)

[Claims] 1) A burner provided at the center of the upper part of the furnace vessel, a cylindrical partition wall surrounding the burner and suspended from the top of the furnace vessel, and a reformer placed between the partition wall and the side wall of the furnace vessel surrounding the partition wall. This fuel reformer is equipped with a reforming tube filled with a hydrogen-rich catalyst, and heats the reforming tube with a heat medium generated by combustion from a burner to reform the reforming raw material gas flowing through the reforming tube into hydrogen-rich gas. The burner tube is provided with a burner tube suspended from around the burner within the partition wall, and a combustion tube that stands upright from the bottom of the furnace vessel and surrounds a portion from the lower end of the burner tube to form a heat medium passage. A fuel reformer characterized by: