JPH0519481B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a reaction tube of a reforming tube for producing hydrogen-enriched gas (reformed gas) from a mixture of hydrocarbons and steam by catalytic action.

[Prior art]

Hydrogen-enriched gas is produced through a reforming reaction in which a mixture of raw material hydrocarbons and steam is brought into contact with a reforming catalyst under heating in a reaction tube filled with a reforming catalyst placed in a reformer. Ru.

Since the reforming reaction is a strong endothermic reaction, and the temperature required for reforming is as high as 700 to 950°C, the reaction tube is heated by high-temperature combustion gas generated by combustion in a burner, and the gas passes through the tube. The amount of heat required for the reforming reaction of the raw material is provided.

5 to 8 show reaction tubes of a conventional reformer for producing hydrogen-enriched gas.

In FIG. 5, a reaction tube 1 is filled with a reforming catalyst 2, and a mixture of raw material hydrocarbon and steam is supplied along arrow A, flows through the reaction tube 1 along arrow B, and flows through arrow C. is discharged along the

On the other hand, high-temperature combustion gas is supplied along arrow D and undergoes countercurrent heat exchange with the raw material mixture.

However, since the exit section 3 of the reaction tube through which the high-temperature reformed gas flows, heat is transferred from the high-temperature combustion gas near the flame, so the surface temperature of the reaction tube, especially near the exit section 3, becomes extremely high. This method is not economical because it requires expensive heat-resistant materials (such as high-nickel steel), and it also has the disadvantage of shortening the life of the reaction tube because the surface temperature of the reaction tube is high.

Fig. 6 shows a case where the raw material mixture flows A, B, and C and the combustion gas flow D flow in parallel, and the temperature of the raw material mixture at the reaction tube inlet 4 where it comes into contact with the high-temperature combustion gas near the flame is 400 to 600°C. and the surface temperature of the reaction tube becomes low.

However, at the reaction tube outlet 3, heat must be given to the high-temperature reformed gas, so a higher combustion gas temperature is required, and therefore the heat generated by combustion cannot be used effectively, resulting in poor thermal efficiency and It requires a large amount of fuel to form and has high operating costs.

The reaction tube 1 of FIG. 7 has an internal heat exchanger tube 5, and the raw material mixture flows through the reaction tube 1 along arrows A, B, B' and is discharged along arrow C.

The heat of the reformed gas is recovered by the internal heat transfer tube 5 by exchanging heat with the raw material mixture.

However, as in the case of FIG. 5, the flow B of the raw material mixture and the flow D of the combustion gas flow countercurrently, which has the drawback of increasing the reaction tube surface temperature.

FIG. 8 shows a case where the raw material mixture is preheated by the internal heat transfer tube 5, and as in the case of FIG. 6, the raw material mixture and combustion gas flow in parallel, resulting in poor thermal efficiency.

[Purpose of the invention]

The present invention aims to eliminate the above-mentioned conventional drawbacks, increase thermal efficiency, reduce fuel consumption, and provide a reaction tube for a hydrogen-enriched gas production reformer with a low reaction tube surface temperature. be.

[Structure of the invention]

To achieve the above object, the present invention provides a reaction tube for a reformer for producing hydrogen-enriched gas, in which the reaction tube is divided into an upper reaction zone and a lower reaction zone by a partition, and the A raw material gas conduit extending downward in the reaction zone and a reformed gas conduit penetrating the partition wall and extending upward in the upper reaction zone are provided, and the reformed gas conduit is guided outside the reaction tube and The present invention is characterized in that a raw material gas supply pipe is provided in the reaction zone, and a reforming catalyst is filled in the upper reaction zone, lower reaction zone, and raw material gas conduit.

FIG. 1 shows a first embodiment of the reaction tube of the present invention,
The reaction tube 1 is divided into an upper reaction zone 7 and a lower reaction zone 8 by a partition wall 6. A raw material gas conduit 9 passes through the partition wall 6 and extends downward in the lower reaction zone 8.
A reformed gas conduit 10 is provided that penetrates the partition wall 6 and extends upward in the upper reaction zone 7, and the reformed gas conduit 10 is led out of the reaction tube 1 via a reformed gas exhaust pipe 12.

Furthermore, the upper reaction zone 7, the lower reaction zone 8, and the raw material gas conduit 9 are each filled with a reforming catalyst.

In this reaction tube 1, a raw material mixture of raw material hydrocarbon and steam is supplied from a raw material supply pipe 11 to an arrow A.
It flows down along the arrows B and B while contacting the reforming catalyst in the upper reaction zone 7, and starts the reforming reaction.

Note that the reforming catalyst used in the present invention is not particularly limited, and conventionally used reforming catalysts for producing hydrogen can be used.

Furthermore, conventionally used natural gas, propane, butane, naphtha, and the like are used as raw material hydrocarbons.

The amount of heat required for the reforming reaction in the upper reaction zone 7 is supplied by countercurrent heat exchange with relatively low temperature combustion gas flows D ₁ and D ₁ .

The raw material mixture flowing down the upper reaction zone 7 passes through the partition wall 6
The flow is blocked by the raw material gas conduit 9 and flows down along the arrow B ₁ , reverses from the bottom of the reaction tube 1 and rises along the wall side of the reaction tube 1 along the arrows B ₂ and B ₂ do.

The amount of heat required for the reforming reaction in the raw gas conduit 9 is supplied by heat exchange with the flows of B _{2 and} B ₂ flowing in parallel with the flows of high-temperature combustion gases D 2 and D ₂ .

The reforming reaction is almost completed in the vicinity of the partition wall 6 of the streams B ₂ , B ₂ , and the high temperature reformed gas flows B ₂ , B ₂
is collected at the partition wall 6, and the reformed gas conduit 10
While rising along the arrow _B3 inside, it exchanges heat with the raw material mixture flows B and B, giving it heat, and is discharged to the outside of the reaction tube while its temperature decreases.

Note that the temperature of the reforming catalyst layer in the upper reaction zone 7 is usually 400 to 700°C, the temperature of the catalyst layer in the raw gas conduit 9 is 500 to 800°C, and the temperature of the catalyst layer surrounding the raw gas conduit 9 is 600 to 950°C. ℃, is.

2A and 2B show a second embodiment of the present invention, which differs from the first embodiment only in that two reformed gas conduits 10 ₁ and 10 ₂ are provided.

FIG. 3 shows a third embodiment of the present invention, in which four reformed gas conduits 10 ₁ , 10 ₂ , 10 ₃ and 10 ₄ are provided.

The reaction tube 1 of the present invention is installed in a heating furnace 14 having a burner 13 to constitute a reformer 15, as shown in FIG.

Note that the combustion gas is discharged from the combustion gas outlet 16.

〔Effect of the invention〕

As described above, according to the present invention, a single reaction tube has both countercurrent and parallel current. That is, the combustion gas flow D ₁ countercurrent to the raw material gas flow B,
and D ₂ cocurrent with B ₂ .

Therefore, the flow of hot combustion gases D ₂ near the flame
Since the part where the heat is transferred is relatively low temperature gas flow B ₂ before the reforming reaction is completed, the reaction tube surface temperature can be lowered, and the reaction tube material is expensive as in the past. This eliminates the need for heat-resistant materials.

Since the low-temperature combustion gas D ₁ only needs to transfer heat to the low-temperature raw material gas B, heat can be used effectively and high thermal efficiency can be obtained.

Furthermore, since the reformed gas conduit is provided in the upper reaction zone, the high amount of heat held by the reformed gas after the reforming reaction can be given to the raw material gas by exchanging heat with the raw material gas. The heat imparted from the combustion gas to the raw material gas can be reduced, and therefore the amount of fuel required to form the combustion gas can be reduced.

In addition, since the temperature of the reformed gas discharged from the reaction tube is lowered by heat exchange with the raw material gas, it is not necessary to connect the connecting pipe from the reformed gas discharge pipe 12 to other equipment (not shown) in an expensive manner. It is economical as it does not require the use of heat-resistant materials.

In other words, the reaction tube of the present invention makes effective use of the combustion gas temperature of the conventional reaction tube shown in FIG. 5, downgrades the reaction tube material of the reaction tube shown in FIG. It can be said that the reaction tube combines the characteristics of each type, such as high heat recovery efficiency.

[Brief explanation of drawings]

Fig. 1 is a longitudinal cross-sectional schematic diagram showing the first embodiment of the reaction tube of the present invention, Fig. 2 A is a longitudinal cross-sectional schematic diagram showing the second embodiment, and Fig. 2 B is a cross-sectional schematic diagram of the X-X arrow. Fig. 3 is a schematic cross-sectional view showing the third embodiment, Fig. 4 is a schematic vertical cross-sectional view of a reformer equipped with the reaction tube of the present invention, Fig. 5, Fig. 6, Fig. 7, and FIG. 8 is a schematic vertical cross-sectional view of a conventional reaction tube. DESCRIPTION OF SYMBOLS 1... Reaction tube, 6... Partition wall, 7... Upper reaction zone, 8...
Lower reaction zone, 9... raw material gas conduit, 10... reformed gas conduit.

Claims (1)

[Claims] 1. In a reactor of a reformer for producing hydrogen-enriched gas, the reaction tube is divided into an upper reaction zone and a lower reaction zone by a partition wall, and a raw material that penetrates the partition wall and extends downward into the lower reaction zone. A gas conduit and a reformed gas conduit penetrating the partition wall and extending upward in the upper reaction zone are provided, the reformed gas conduit is guided outside the reaction tube, and a raw material gas supply pipe is connected to the upper reaction zone. A reaction tube for a reformer for producing hydrogen-enriched gas, characterized in that the upper reaction zone, the lower reaction zone, and the raw material gas conduit are filled with a reforming catalyst.