JPS647119B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydrocarbon reforming furnace, and more particularly to a hydrocarbon reforming furnace for producing pressurized hydrogen for use in fuel cells.

FIG. 1 is a flow sheet showing a conventional hydrogen production system to be supplied to a fuel cell. This system mixes steam 101 into hydrocarbon raw material (methane) 100 and heats it in a reforming furnace (reaction tube) 10.
2, where it is reformed into hydrogen-rich gas in the presence of a catalyst, and further subjected to a shift reaction in a high-temperature shift furnace 105 and a low-temperature shift reactor 106, and further refined into highly concentrated hydrogen, which is then supplied to a fuel cell 107. It is something. In the figure, 108 and 109 are waste heat boilers, and 110 and 111 are boiler water lines, respectively.

Since the reforming furnace used in the above hydrogen production system is generally a pressurized system with several atmospheres of pressure in both the reaction gas system and the combustion system, it is necessary to construct the entire system with a pressure-resistant vessel.

On the other hand, for steam reforming of methane, etc., a steam reheater furnace is used for the chemical industry, which heats the reaction tube with burner combustion heat, but in the case of fuel cells, burner combustion is used for the purpose of compactness. An excellent catalytic combustion method has been proposed. This method promotes the combustion reaction (oxidation reaction) even at relatively low temperatures by mixing fuel and air in advance and passing the mixture through a combustion catalyst layer, allowing a high-temperature atmosphere to survive. It can also be called a combustion method. Packed bed heat transfer has significantly better heat transfer efficiency than normal convection or radiation heat transfer, so overall compactness can be achieved.

SUMMARY OF THE INVENTION In view of the prior art described above, an object of the present invention is to provide an extremely compact reforming furnace suitable for reforming hydrocarbons, particularly for producing pressurized hydrogen for combustion batteries.

The present invention provides a reaction vessel partitioned into an upper preheating zone and a lower combustion zone by a tube sheet, a double reaction tube fixed to the tube sheet and consisting of an inner tube and an outer tube,
It has a reforming catalyst layer filled between the inner tube and the outer tube, and after the hydrocarbon feed gas is preheated in the upper preheating zone, it is reacted through the reforming catalyst layer in the double reaction tube in the combustion zone. , while the combustion catalyst is taken out of the system through the inside of the inner tube, in the lower combustion zone, the combustion catalyst is held between the concentric inner and outer double grids, the double reaction tube is arranged therein, and the combustion catalyst is It is characterized by being configured to introduce fuel and air into the layer.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a front sectional view of the reforming furnace of the present invention, and FIG. 3 is a plan sectional view taken along the - line. In the figure, this reforming furnace consists of a vertical cylindrical vessel in which a lower body vessel 1, an intermediate piece 2 and a top cover 3 are connected by body flanges 4 and 5. As shown in Fig. 3, the cross-sectional structure of the lower part is one in which a heat-insulating castable 10 is lined inside the pressure-resistant vessel 1 as the outermost shell, and the fuel gas supplied from the nozzle 16 (Fig. 2) is placed inside the outermost pressure-resistant vessel 1. A layer 11 of a mixture of air and air is formed. That is, layer 1
Reference numeral 1 denotes a space layer formed between the cylindrical lattice 12 and the heat insulating castable 10, which functions as a distributor of the air-fuel mixture and as a container for the combustion catalyst 13. The temperature of the combustible gas is relatively low, and the high temperature atmosphere of the catalyst layer 13 is cut off by the combustible gas layer, so the lined castable 10 can be relatively thin. The interior of the intermediate piece 2 and the top cover 3 is filled with the reaction gas supplied from the nozzle 22, which is also at a relatively low temperature, so that a heat insulating effect similar to that of the lower vessel can be obtained.

The raw material gas, which is a mixture of raw material methane and steam, enters the main body vessel from the nozzle 22 of the intermediate piece 2, is supplied from the guide shroud 23 to the upper part of the intermediate piece 2 and the inside of the top cover 3, and is filled with a heating medium. Flow down the middle piece 2,
The reactant gas is preheated by absorbing sensible heat from the reaction tube (inner tube) 7 and enters the outer reaction tube 6. The reaction tube outer tube 6 is provided on a tube plate 20 fixed to the lower part of the intermediate piece 2, and an inner tube 7 is located in the center to form a double tube structure. A reforming catalyst is filled between the inner tube 7 and the outer tube 6, and the raw materials react with heat supplied from the external combustion catalyst particles 13 to generate hydrogen-rich gas. The generated gas stops at the bottom cap of the outer tube 6, rises up the inner tube, and reaches the generated gas collecting headers 8 and 9 provided in the top cover 3.
are collected and transported out of the system through nozzles 27 and 28. In the upper part of the tube plate 20 of the intermediate piece 2, the gaps between the inner tubes 7 are filled with heat transfer particles such as ceramic balls. By forming the packed layer in the intermediate piece 2 in this way, the raw material gas can be effectively preheated in a narrow space, and
The sensible heat of the reaction product gas can be recovered without loss, and the purpose of cooling the product gas can be achieved.
Therefore, the high temperature reaction gas is also discharged from the nozzles 27 and 26 after being sufficiently cooled. Normally, the reaction product gas is at a high temperature of 800 to 900°C, but it is sufficiently cooled by the cooling effect of the packed bed, so the nozzles 27 and 2
6. Heat-resistant design will not be so difficult. Therefore, although the reactor has high-temperature conditions, the main bodies 1, 2, and 3 of the heat-resistant vessel can have a sufficiently safe structure by simply lining each of the bodies 1, 2, and 3 with a thin refractory and heat-insulating castable.

To explain the details of the structure of each part, the reaction tube is arranged in the main body vessel 1 with an outer tube 6 fixed to a tube plate 20 as shown in FIG.
As shown in FIG. 4 and FIG. is fixed. Therefore, when assembling the main body intermediate piece 2, each inner tube 7 is simultaneously inserted into each outer tube 6 with a lid placed on top, and the entire device is assembled. In the gap between the inner tube 7 and the outer tube 6, there is a reforming decomposition medium 31 as shown in FIG.
Furthermore, a porous catalyst receiving tray 18 is provided at the lower end of the inner tube 7 to hold the reformed decomposition medium.
The reaction gas flows down from the upper part of the outer tube 6, passes through the catalyst receiver 18, rises in the inner tube 6, and reaches the upper collecting headers 9 and 8. The upper part of the inner tube 7 of the reaction tube, that is, the preheating zone of the raw material gas, is provided with longitudinal fins 29 radially as shown in FIG. 4A to help dissipate heat to the thermal particles 25. Fins 30 are provided, and combustion catalyst particles 13 are provided.
The efficiency of heat supply from the reaction tube to the outer tube 6 can be promoted. Providing such a fillet is advantageous in increasing the overall heat transfer performance and making the device more compact.

On the other hand, the outer tube 6 is fixed to a tube plate 20 provided at the lower part of the intermediate piece 2 in the same manner as in a conventional heat exchanger. As shown in detail in FIG. 5, a heat insulating layer 21 is provided at the bottom of the tube sheet 20 to protect the tube sheet from the high heat of the combustion zone caused by the combustion catalyst. The raw material gas is supplied from the intermediate piece 22, and a guide shroud 23 is provided as shown in FIG. 7 in order to guide it evenly to the upper part of the particle layer 25. That is, since the shroud 23 extends over the entire circumference of the cylinder, the raw material gas is quickly distributed over the entire circumference, and is uniformly supplied over the entire surface from the upper part of the particle layer 25.

The combustion zone within the body 1 is located within the body 1 as described above.
A heat insulating castable 10 is thinly stretched on the inside of the lattice, and concentric cylindrical lattices 12 and 14 filled with a combustion catalyst 13 are arranged inside the lattice with a space 11 interposed therebetween. The grids 12 and 14 are connected to the combustion catalyst 13.
It is preferable to use a louver-like structure that allows gas to freely pass through while retaining the gas. grid 12,
14 is provided so that the combustible air-fuel mixture is uniformly supplied in the longitudinal direction of the reaction tube and always provides a uniform amount of heat to the heat exchanger tube. Since the outer grid 12 is cooled by the relatively low temperature combustible gas layer 11, its temperature is not high and it can be structurally rigid. On the other hand, the inner lattice 14 where combustion gas gathers is
Since it is directly exposed to the high temperature of combustion gas, consideration must be given to heat-resistant design. As shown in Figures 2 and 3,
If the lattice is filled with particles 15 that are coarser than the catalyst 13, the inner lattice 14 will be supported by the particles from inside and outside.In other words, the cylindrical lattice 14 will be buried in the particles, so a special Support is no longer required. However, in this case, a particle receiving tray 33 is required. The reason why the filler particles 15 are made larger than the catalyst 13 is to reduce the resistance of the collected gas.

As described above, according to the present invention, by using a double pipe filled with a catalyst and filling the outside with a combustion catalyst, relatively low-temperature combustible gas is supplied from the outermost side. The heat insulating layer of Betsuru can be made thinner. In addition, the inner tube is fixed to the upper lid of the reactor, and the outer tube is fixed to the tube plate of the reactor main body.
Since these are overlapped during assembly, the apparatus becomes extremely compact, and maintenance such as catalyst replacement and cleaning becomes easy, thereby providing a reforming furnace with excellent reaction performance and maintenance.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of a system including a hydrocarbon reformer for producing hydrogen for fuel cells, FIG. 2 is a front cross-sectional view showing an embodiment of the hydrocarbon reformer of the present invention, and FIG. 3 is a sectional view taken along the - line, FIG. 4 is a detailed view of the double reaction tube in FIG. 2, FIG. 4A is a sectional view showing a modified example of the double reaction tube, and FIG. The figure is a cross-sectional view of the reaction tube outer tube near the tube plate attachment part, FIG. 6 is a partial view showing the outer tube inserted into the outer lattice in the main vessel vessel,
FIG. 7 is a partial view showing details of the vicinity of the reaction gas inlet of the intermediate piece. 1... Main body hetsusel, 2... Main body intermediate piece,
3...Main body top cover, 6...Reaction tube outer tube, 7
... Reaction tube inner tube, 12 ... Outer cylindrical grid, 14 ...
...Inner cylindrical grid, 15...Filling machine, 16...Fuel, air inlet nozzle, 20...Tube sheet.

Claims (1)

[Scope of Claims] 1. A reaction vessel partitioned into an upper preheating zone and a lower combustion zone by a tube sheet, a double reaction tube fixed to the tube sheet and consisting of an inner tube and an outer tube, and the inner tube. It has a reforming catalyst layer filled between the tube and the outer tube, and after preheating the hydrocarbon raw material gas in the upper preheating zone, it is reacted through the reforming catalyst layer in the double reaction tube in the combustion zone, and further While the combustion catalyst is taken out of the system through the inner tube, in the lower combustion zone, the combustion catalyst is held between the concentric inner and outer double grids, the double reaction tube is placed in this, and the combustion catalyst layer is A hydrocarbon reforming furnace configured to introduce fuel and air into the reactor. 2. A hydrocarbon reforming furnace according to claim 1, characterized in that the fuel and air in the combustion zone are supplied as a mixture from the outer grate to the inner grate in a cross-flow direction with respect to the reaction tube. 2. The hydrocarbon according to claim 1, characterized in that the inner lattice of the combustion zone is filled with heat carrier particles larger than the combustion catalyst particles, and the inner lattice is supported by the particles inside and outside. Reforming furnace. 3. The hydrocarbon reforming furnace according to claim 1, characterized in that the preheating zone is filled with heat carrier particles. 4. Claim 1 is characterized in that the inner tube of the reaction tube has radial vertical fins in the upper raw material gas preheating zone, and the outer tube of the reaction tube is similarly provided with vertical fins over its entire length. Hydrocarbon reforming furnace. 5. In claim 1, the reaction tube inner tube is attached to the reactor upper lid via a gas header,
A hydrocarbon reforming furnace characterized in that a reaction tube outer tube is attached to the reactor body via a tube plate, and when these are assembled, a double reaction tube is constructed.