JPS6111133A - Endothermic reaction device - Google Patents

Abstract

PURPOSE:To carry out an endothermic reaction with high thermal efficiency by packing a heat conductive packing material in a passage of high temp. gas enclosed by an external tube of a reaction tube and a vessel for the reactor and making the diameter of the part near the top end of the external tube of the reaction tube thinner than the diameter of other part. CONSTITUTION:Raw material gas is introduced from an inlet nozzle 8, and the gas flows into a reaction chamber 4 through a manifold 7. The reaction chamber 4 is heated by the high temp. gas through the external tube 2 for the reaction tube, and is heated also by the produced gas passing through a regeneration chamber 6 interposing an internal tube 3 of the reaction tube. The raw material gas introduced into the reaction chamber 4 is heated by these heat and an endothermic reaction is caused by the effect of catalyst 5. The gas produced by the reaction flows into the regeneration chamber 6 from the bottom of the reaction chamber 4, and discharged to a manifold 9 for the produced gas from the top end of the regeneration chamber 6. In this stage, a part of the sensible heat of the produced gas is recovered by the reaction chamber 4 side through the internal tube 3 of the reaction tube.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an endothermic reaction apparatus, and particularly to an improvement in an endothermic reaction apparatus equipped with a plurality of double-tube regeneration type reaction tubes.

[Technical background of the invention and its problems] As is known, a double-tube regeneration type reaction tube is composed of an outer reaction tube that is closed at one end and an inner reaction tube that is open at both ends. A pipe line with an annular cross section surrounded by an outer reaction tube and an inner reaction tube constitutes a reaction chamber, and this reaction chamber is filled with a catalyst as required. The raw material gas is introduced through the opening of the outer reaction tube, passes through the reaction chamber, reaches the closed portion of the outer reaction tube, and is guided to one end of the inner reaction tube. The inside of the reaction tube inner tube is a regeneration chamber, and the reaction product gas passes through the regeneration chamber and is discharged from the other end side of the reaction tube inner tube. On the other hand, the reaction heat required for the endothermic reaction and the sensible heat required to raise the raw material gas to the desired reaction temperature are mainly generated by heating the outer tube of the reaction tube from the outside with combustion gas or other high-temperature gas. A portion of the reaction product gas is also supplied to the reaction chamber by heating the reaction tube as it exits through the regeneration chamber.

By the way, in the above-mentioned double-tube regeneration type reaction tube, the gas inlet/outlet is only at one end of the reaction tube, so there is no need to fix the other end, that is, the closed part of the outer tube of the reaction tube. It is easy to deal with thermal expansion, and as mentioned above, a part of the sensible heat of the reaction product gas is recovered in the regeneration chamber, so the thermal efficiency of the device is improved, and
It has an excellent feature in that the exhaust temperature of the reaction product gas is lowered, so that the cost of post-processing equipment for the product gas is reduced. Therefore, it can be particularly suitably used in steam reforming equipment and the like that require an endothermic reaction to occur at high temperatures.

Now, a large number of double-tube regeneration type reaction tubes as described above are arranged densely, and high-temperature gas such as combustion gas is passed through the high-temperature gas passage outside the reaction tube outer tube in a countercurrent direction to the gas in the reaction chamber. A structure is already known in which the high temperature gas passage is filled with a heat transfer filler for promoting heat transfer to the reaction tube outer tube. The reactor having such a configuration has excellent advantages such as being able to design the whole compactly and having high thermal efficiency because the sensible heat of the high temperature gas can be used for the reaction even in the relatively low temperature part. Has characteristics. However, in cases where the reaction temperature needs to be raised to high temperatures (750 to 850°C), such as in steam reforming reactions, it has become clear that conventional methods cannot take full advantage of the above characteristics. ing.

That is, the rate of heat transfer from the high temperature gas passage containing the heat transfer filler material to the outer tube of the reaction tube increases as the flow rate of the gas flowing through the high temperature gas passage increases. Therefore, in order to make the apparatus more compact or to increase thermal efficiency, it is desirable to increase the flow rate of the hot gas by arranging the reaction tubes as densely as possible and reducing the cross-sectional area of the hot gas passage. However, there are some limitations to increasing the flow rate of hot gas. One is that increasing the flow rate increases the pressure loss on the high-temperature gas side, and the other is that increasing the heat transfer rate increases the temperature of the outer tube of the reaction tube, especially in the blocked part of the reaction tube. The problem is that the usage limit of the material is exceeded in the vicinity. Therefore, there is a problem in that the above-mentioned features cannot be fully utilized in terms of compactness or thermal efficiency.

[Purpose of the Invention] The present invention was made to solve the above-mentioned problems, and its purpose is to prevent the tip of the reaction tube from being damaged even in the case of endothermic reactions that require high temperatures such as steam reforming reactions. An object of the present invention is to provide an endothermic reaction device that can perform an endothermic reaction with high thermal efficiency by making the device more compact while preventing overheating.

[Summary of the invention] In order to achieve the above object, the present invention includes a reactor vessel,
A plurality of reaction tubes are arranged inside the reactor container and have an outer reaction tube and an inner reaction tube, and are surrounded by the outer reaction tube and the inner reaction tube to form a reaction chamber. The reaction chamber is heated by passing high-temperature gas from one end of the reaction tube into the high-temperature gas passage surrounded by the reaction tube and the reactor container, and the reaction chamber is heated and discharged from the other end to the outside. In an endothermic reaction apparatus, the raw material gas is made to flow in from the other end of the outer reaction tube, pass through the reaction chamber, become a product gas, and flow from one end through the inner side of the reaction tube and out the other end. , a high-temperature gas passage surrounded by the reaction tube and the reactor container is filled with a heat transfer material, and the diameter of a portion near the tip of the reaction tube is made smaller than other portions; In particular, an endothermic reaction device characterized in that the length of the reaction tube is narrower than other parts over 5% or more of the total length of the reaction tube.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. The figure is a sectional view showing an example of a partial configuration of an endothermic reaction device according to the present invention. In the figure, reactor vessel 1
Inside the reaction tube, double-tube regeneration type reaction tubes consisting of an outer reaction tube 2 and an inner reaction tube 3 are densely arranged.

A passage having an annular cross section surrounded by the reaction tube outer tube 2 and the reaction tube inner tube 3 constitutes a reaction chamber 4, which is filled with a catalyst 5 that promotes an endothermic reaction. Also,
The distal end 2a (lower end in the figure) of the outer reaction tube 2 is closed, and the gas produced after the reaction exits the reaction chamber 4 from here to the regeneration chamber 6 formed inside the inner reaction tube 3. Further, the upper end of the reaction tube outer tube 2 is opened to communicate with the raw material gas manifold 7, and after the raw material gas is introduced from the raw material gas inlet nozzle 8, the raw material gas It flows into the reaction chamber 4 through the manifold 7.On the other hand, this reaction chamber 4 is connected to the reaction tube outer tube 2.
The raw material gas flowing into the reaction chamber 6 is heated by the produced gas passing through the reaction tube inner tube 3 and the regeneration chamber 6, and by the action of this heat and the catalyst 5, the raw material gas flowing into the reaction chamber 6 is heated. As the temperature increases, an endothermic reaction occurs. Further, the product gas generated by this reaction flows into the regeneration chamber 6 from the lower end of the reaction chamber 4, passes through this regeneration chamber 6, and is discharged from the upper end of the regeneration chamber 6 to the product gas manifold 9. A part of the sensible heat of the produced gas is recovered to the reaction chamber 4 side via the reaction tube inner tube 3.

Furthermore, the reaction tube tip 2a, which is close to the tip of the reaction tube outer tube 2, is made conical and thinner as it approaches the tip compared to other parts over a length of 5% or more of the total length of the reaction tube. Similarly, in this part of the inner reaction chamber 4, the flow path area becomes narrower as it approaches the tip.

On the other hand, high-temperature gases such as combustion gas and industrial gas are introduced from a high-temperature gas inlet nozzle 10, pass through a high-temperature gas chamber 11, and are distributed to high-temperature gas passages 12 formed around each of the reaction tube outer tubes 2. It has become. In addition, these high temperature gas chambers 1
1 and hot gas passageway 12 are substantially filled with filled heat transfer material 13 . And this filling heat transfer material 13
As such, heat-resistant particles such as alumina balls can be suitably used. Further, the high temperature gas is supplied to the high temperature gas passage 12.
The high-temperature gas is discharged from the high-temperature gas outlet nozzle 14 through the high-temperature gas passage 12, and by heating the reaction tube outer tube 2, the sensible heat is imparted to the raw material gas in the reaction v4. Here, the high-temperature gas passage 12 becomes narrower as the tip portion 2a of the reaction tube approaches the tip compared to other portions, so the flow path area is wider at the inlet portion (lower portion in the figure) than at other portions. It has become. In addition, 15
is the product gas outlet nozzle.

The endothermic reaction apparatus having such a configuration includes a plurality of densely arranged double-tube regeneration type reaction tubes, and the high-temperature gas passage 12 surrounded by the reaction tube outer tube 2 and the reactor container 1 is substantially The reaction tube is filled with a heat transfer material 13, and a portion of the reaction tube outer tube 2 near the tip 2a is made thinner than other portions over a length of 5% or more of the total length of the reaction tube. As a result, the cross-sectional area of the high-temperature gas passage 12 is wider in the portion close to the tip 2a of the reaction tube outer tube 2, that is, in the high-temperature portion of the reaction tube than in other portions, so that the high-temperature portion of the reaction tube is By reducing the flow rate of the high temperature gas in this part, the heat transfer rate from the high temperature gas to the reaction tube outer tube 2 in this part can be reduced, and the pressure loss on the high temperature gas side can be reduced. In addition, since the flow path area of the reaction chamber 4 is narrower in the high-temperature part of the reaction tube than in other parts, the flow rate of the reaction gas in the high-temperature part is increased, thereby creating a gap between the reaction gas and the reaction tube outer tube 2. The heat transfer rate can be increased. Both of these reductions in heat transfer rate on the high-temperature gas side and increases in heat transfer rate on the reaction gas side have the effect of lowering the temperature of the reaction tube outer tube 2 and preventing overheating. .

Therefore, in this example, compared to the conventional method, it is possible to arrange the reaction tubes more densely, and it is also possible to increase the average heat transfer rate of the reaction tubes as a whole, making it more compact and extremely thermally efficient. It becomes possible to obtain a high endothermic reaction device.

In the above embodiment, the vicinity of the tip 2a of the outer reaction tube 2 is conical, but the shape of this portion does not necessarily have to be conical. For example, a straight tube with a small diameter may be used for this portion. It may also be a stepped tube. In addition, in the above embodiment, high-temperature gas is introduced from the outside as a heat source for heating the reaction tube, but instead of this, fuel gas and combustion air are introduced and combusted inside the reactor container, and the combustion It is also possible to use gas as the hot gas. In this case, it can be used as a partial combustion chamber of the high temperature gas chamber 11 shown in the figure. Furthermore, the combustion chamber may be filled with a catalyst that promotes the oxidation reaction to perform catalytic combustion. It goes without saying that various other modifications can be made without departing from the gist of the present invention, such as by reversing the top and bottom of the reactor vessel 1 shown in the figure.

[Effects of the Invention] As explained above, according to the present invention, even in the case of an endothermic reaction that requires high temperatures such as a steam reforming reaction, the apparatus can be made more compact while preventing overheating of the tip of the reaction tube. An endothermic reaction device capable of carrying out an endothermic reaction with high thermal efficiency can be provided.

[Brief explanation of the drawing]

The figure is a partial cross-sectional configuration diagram showing an embodiment of the present invention. 1... Reactor container, 2... Reaction tube outer tube, 2a...
Reaction tube tip, 3... reaction tube inner tube, 4... reaction chamber,
5... Catalyst, 6... Regeneration chamber, 7... Source gas manifold, 8... Source gas inlet nozzle, 9... Produced gas manifold, 10... High temperature gas inlet nozzle, 11.
...High temperature gas chamber, 12...High temperature gas passage, 13...
Filled heat transfer material, 14... High temperature gas outlet nozzle, 15...
・Produced gas outlet nozzle.

Claims (3)

[Claims] (1) A reactor container, which is disposed inside the reactor container, has an outer reaction tube and an inner reaction tube, and is surrounded by the outer reaction tube and the inner reaction tube to form a reaction chamber. the reaction chamber is heated by passing high temperature gas from one end of the reaction tube outer tube into a high temperature gas passage surrounded by the reaction tube outer tube and the reactor container; The raw material gas is discharged to the outside from the other end, and the raw material gas is caused to flow in from the other end of the outer tube of the reaction tube, pass through the reaction chamber, and become a generated gas. In the endothermic reaction apparatus configured, the high temperature gas passage surrounded by the reaction tube outer tube and the reactor container is filled with a heat transfer material, and the diameter of the portion near the tip of the reaction tube outer tube is reduced. An endothermic reaction device characterized by being configured to be thinner than other parts. (2) Claim (1) characterized in that the diameter of the portion near the tip of the outer tube of the reaction tube is made smaller than other portions over a length of 5% or more of the total length of the reaction tube. ). (3) The reaction tube according to claim (1), characterized in that the diameter of the portion near the tip of the outer reaction tube is configured to be tapered continuously or stepwise toward the tip. Endothermic reactor.