JPH0372562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steam reforming reaction device, and more particularly, a reaction tube containing a steam reforming reaction catalyst is embedded in a combustion catalyst layer, and a mixed fluid of steam and hydrocarbon compounds is contained in the reaction tube. The present invention relates to a steam reforming reaction device that conducts a steam reforming reaction in a reaction tube by absorbing combustion heat generated in a combustion catalyst layer.

FIG. 1 is a sectional view showing a schematic configuration diagram of a conventional steam reforming reaction apparatus.

A container body 2 lined with a heat insulating material 1 is filled with, for example, an iron-based, vanadium-based, or platinum-based combustion catalyst to form a combustion catalyst layer 3.
In this combustion catalyst layer 3, a large number of reaction tubes 4 are arranged circumferentially around the central axis of the container body 2, respectively. The upper part of this reaction tube 4 is supported by a tube plate 5 installed on the combustion catalyst layer 3, and the lower part is supported by a fuel-air inlet 6 provided below the container body 2.
It extends close to. The reaction tube 4 has a double tube structure, and the inner space formed by the tube wall is simply hollow, and the outer space is filled with, for example, molybdenum or cobalt. A nickel-based steam reforming reaction catalyst 7 is filled.

A fuel cell (not shown) is located below the container body 2.
A fuel-air inlet 6 is formed into which a mixture 10 of fuel 8 and combustion air 9 consisting of unreacted components discharged from the anode side of the combustion chamber is supplied. An exhaust gas outlet 11 is provided on the upper wall of the container body 2 for discharging combustion gas generated within the container body 2.

A top cover 12 is arranged above the tube sheet 5, a raw material preheating chamber 13 is formed between the tube sheet 5 and the top cover 12, and a raw material inlet 14 is provided in the raw material preheating chamber 13. A raw material 15 in which a hydrocarbon compound such as naphtha or natural gas and steam are mixed in a predetermined ratio is fed from the raw material inlet 14,
After being preheated through the raw material preheating chamber 13, it is introduced into the outer peripheral space of the reaction tube 4. In this outer peripheral space, in the presence of the steam reforming reaction catalyst 7, hydrocarbons and steam react and are modified into carbon monoxide and hydrogen while absorbing the combustion heat generated within the combustion catalyst layer 3. The produced gas 16 makes a U-turn at the lower end of the reaction tube 4, passes through the inner space, is taken out from the produced gas outlet 17, is supplied to the anode side of the fuel cell, and participates in the cell reaction.

By the way, in this conventional steam reforming reactor,
Since the fuel 8 and combustion air 9 are supplied to the combustion catalyst layer 3 in a pre-mixed state, most of the fuel 8 is burned near the fuel-air inlet 6.

On the other hand, the reforming reaction of the raw material 15 (steam and hydrocarbons) generally occurs relatively close to the inlet of the reaction tube 4, although it varies somewhat depending on the activation ability of the steam reforming reaction catalyst 7. Curve X in FIG. 2 is a line showing the distribution of heat absorption due to the steam reforming reaction in the axial direction of the reaction tube 4, and heat absorption occurs locally in zone a near the entrance of the reaction tube 4. It is being said.

Therefore, in this conventional device, combustion does not take place where the most heat is needed for the steam reforming reaction.
The yield of produced gas is poor. Therefore, a method has been taken to suppress the combustion reaction rate by mixing an inert filler such as alumina balls into the combustion catalyst layer 3, but this method is not sufficiently effective, and furthermore, the combustion catalyst particles and the inert filler are mixed into the combustion catalyst layer 3. It has drawbacks such as not being able to mix things uniformly.

SUMMARY OF THE INVENTION An object of the present invention is to provide a steam reforming reaction apparatus that eliminates the above-mentioned drawbacks of the prior art and allows efficient steam reforming reactions.

In order to achieve this object, the present invention embeds a reaction tube containing a steam reforming reaction catalyst in a combustion catalyst layer, and supplies fuel and combustion air to the combustion catalyst layer in the presence of the combustion catalyst. combust the fuel with
On the other hand, a mixed fluid of steam and a hydrocarbon compound is passed through the reaction tube to absorb the combustion heat generated in the combustion catalyst layer and perform a steam reforming reaction in the presence of a steam reforming reaction catalyst. In the reforming reaction device, the fuel and combustion air are supplied to the combustion catalyst layer from separate systems, and the portion corresponds to the portion where the largest amount of heat is absorbed in the steam reforming reaction in the flow direction of the mixed fluid in the reaction tube. It is characterized in that the combustion state of the fuel is adjusted so that the amount of heat generated is greatest in the vicinity.

Next, embodiments of the present invention will be described using FIGS. 2 to 4.

The difference between the steam reforming reaction apparatus of the present invention shown in FIG. 3 and the conventional one shown in FIG. , through which combustion air 9 is supplied to the combustion catalyst layer 3, and a fuel inlet 19 through which only the fuel 8 is introduced is provided at the lower part of the container body 2.

The distal end of the air supply pipe 18 extends close to the tube plate 5, and a large number of small holes 20 are spirally bored in the peripheral wall thereof. Combustion air 9 is supplied into the combustion catalyst layer 3 from this small hole 20, and the distribution of this air supply amount is large in the part corresponding to the a zone, as shown by the curve Y in Fig. 2. As shown in FIG.
(see figure).

Since the fuel 8 is introduced from the fuel inlet 19, if the air supply amount is controlled by the small hole 20 of the air supply pipe 18 as described above, combustion will occur mainly near the place where the most heat is needed for the steam reforming reaction. will be held.
Therefore, the steam reforming reaction proceeds efficiently, and the yield of generated gas can be increased. Note that other configurations and the like are the same as those of the prior art described above, so their description will be omitted.

In the embodiment described above, the fuel 8 is introduced from below the container body 2, and the supply pipe 18 is inserted into the inside of the container body 2.
However, on the contrary, it is also possible to introduce the combustion air 9 from below the container body 2 and supply the fuel 8 from a supply pipe inserted inside the container body 2. .

In the embodiment described above, the small holes 20 are provided in the supply pipe 18 in a spiral shape, but the present invention is not limited thereto.
Alternatively, the small holes 20 may be bored in a direction perpendicular to the axial direction of the supply pipe 18, that is, along the circumferential direction of the supply pipe 18.

In the embodiment described above, the amount of air (fuel) ejected was controlled by varying the diameter of the small holes 20 of the supply pipe 18, but in addition to this, the distribution of the small holes 20 was varied to control the amount of air (fuel). The amount of ejection can also be controlled.

The present invention has the above-mentioned configuration, and is capable of supplying necessary and sufficient heat in response to the occurrence of reactions in local zones, which is a characteristic of steam reforming reactions. A steam reforming reaction device is provided that can proceed efficiently and has a high yield.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional steam reforming reactor.
Fig. 2 shows a characteristic curve showing the amount of heat absorbed in the reaction tube accompanying the steam reforming reaction and the distribution state of the air supply amount in the present invention, and Fig. 3 shows the characteristic curve of the steam reforming reactor according to the embodiment of the present invention. The sectional view and FIG. 4 are partially enlarged front views of the supply pipe used in the device. 3... Combustion catalyst layer, 4... Reaction tube, 7... Steam reforming reaction catalyst, 8... Fuel, 9... Combustion air, 15... Raw material, 18... Air supply pipe, 19...
...Fuel inlet, 20...Small hole.

Claims (1)

[Scope of Claims] 1. A reaction tube containing a steam reforming catalyst; a mixed fluid supply system for supplying a mixed fluid of steam and a hydrocarbon compound to the reaction tube; a container body in which the reaction tube is embedded in a combustion catalyst layer, and fuel and combustion air are supplied to the combustion catalyst layer to cause the fuel to burn in the presence of the combustion catalyst; Supplying a mixed fluid of water vapor and a hydrocarbon compound from the mixed fluid supply system and absorbing the combustion heat generated in the combustion catalyst layer,
In a steam reforming reaction device that reforms steam in the presence of a steam reforming catalyst, a fuel supply system that supplies the fuel and a combustion air supply system that supplies combustion air are separate systems, and the fuel or A steam reforming reaction apparatus characterized in that the amount of combustion air supplied becomes maximum in the vicinity of a portion where the maximum amount of heat is absorbed in the steam reforming reaction in the flow direction of the mixed fluid in the reaction tube.