JPH0225653B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a heat exchanger tube in which the outer surface of the tube wall is coated with a catalyst layer, and is particularly applicable to, for example, a shell-and-tube heat exchanger type reaction device. It relates to the structure of a heat exchanger tube in which the outer wall of the heat exchanger tube is coated with a catalyst either directly or by a carrier.

[Prior Art] A typical structure of a reaction device using a catalyst is to fill the reactor with a granular or pelleted catalyst to achieve a desired purpose. However, in conventional reactors, it has not always been easy to reliably transfer and recover the reaction heat due to structural constraints. This will be explained in more detail using the drawings.

FIG. 2 is a sectional view showing the general structure of the multi-tubular heat exchanger type reactor 1, and the illustrated heat exchanger tubes 4 are of a conventionally commonly used normal structure. A pair of fixing plates 3a and 3b are arranged at a predetermined interval at both ends of a cylindrical shell (hereinafter simply referred to as the shell) 2 that forms the main body of the reactor 1. Both ends of the heat tube 4 are fixed through each other. A catalyst bed is provided around the heat exchanger tube 4 by filling it with a granular or pelleted catalyst, and the raw material gas 6
is supplied from a barrel nozzle 7a opened in the side wall of the barrel 2, reacts while passing through the catalyst bed, and produced gas 8 is taken out from the barrel nozzle 7b. On the other hand, a heat exchange medium (for example, water) is supplied from a supply nozzle 9a formed at one longitudinal end of the reactor ₁ in the direction of arrow B1. The heat exchange medium is introduced and inserted into the heat exchange tube 4, and the heat generated by the catalytic reaction is transferred and absorbed by the heat exchange medium. The high-temperature heat exchange medium containing the heat thus recovered is taken out from the discharge nozzle 9b of the reaction device 1 in the direction of arrow _B2 and is effectively utilized.

As a method other than that shown in FIG. 2, there is a method in which the heat exchanger tubes 4 are filled with a granular or pellet-like catalyst. In this method, the raw material gas 6 is passed through the heat exchanger tubes 4, and the heat exchange medium is It is made to pass through the outer circumferential side of the heat exchanger tube 4.

In any case, in the conventional method in which the reaction channel is filled with a granular or pelleted catalyst, the reaction device 1
(or heat transfer tube 4) is filled with catalyst,
Not only is there a large pressure loss due to the passage of the gas, but
The heat retained in the gas body is transferred from the gas body to the heat transfer tube through the catalyst, and the reaction heat recovery efficiency is extremely poor because the contact between the catalysts or between the catalyst and the heat transfer tube 4 is point contact. ing. In view of these points, a catalyst layer 10 (generally, a catalyst is supported on a suitable carrier and coated on the outer wall of the heat transfer tube as shown in FIG. 4 described later, so hereinafter referred to as a catalyst support layer) is formed. However, a so-called tube wall catalytic method has been developed that improves the heat transfer effect to the heat transfer tubes 4.

FIG. 3 is a sectional view showing a multi-tubular heat exchange type reactor 1 to which the heat exchanger tubes 4 of the present invention are applied. The reactor shown in FIG. 3 is basically similar to the reactor shown in FIG. 2, and corresponding parts are given the same reference numerals to avoid redundant explanation. In the reactor shown in FIG. 3, a plurality of (four in FIG. 3) baffle plates 5 are interposed between fixed plates 3a and 3b, passing through heat transfer tubes 4, respectively.
As a result, a zigzag-shaped reaction flow path is formed within the reactor 1. In this way, the gas flow flowing along the reaction flow path becomes turbulent, and the heat exchange efficiency generated between the catalytic reaction heat generated on the surface of the heat exchanger tube 4 and the heat exchange medium passing inside the heat exchanger tube 4 is further increased. It will be done. In the tube wall catalytic method, the flow path for the raw material gas 6 is secured on the outer circumferential side of the tube wall catalyst, so there is little pressure loss, and the catalytic reaction mainly proceeds on the outer wall surface of the heat transfer tube 4. , and the heat transfer from the catalyst support layer to the heat transfer tubes 4 becomes better, resulting in higher heat transfer efficiency.

[Problems to be Solved by the Invention] FIG. 4 is an enlarged cross-sectional view of a portion of a conventional tube wall catalyst type heat transfer tube 4 that is inserted through the fixing plate 3a and the baffle plate 5. The fixed plate 3a and the baffle plate 5 are provided with through holes 11 and 14, respectively, through which the heat exchanger tubes 4 are inserted. Through hole 11 bored in fixed plate 3a
One end of the main body of the heat exchanger tube 4 is inserted through and fixed by welding at the welded portion 13 . That is, the heat exchanger tube 4 is the main tube 1
2, and a catalyst support layer 10 inserted into the outer surface of the main tube 12. The catalyst support layer 10 is formed by supporting a catalyst such as nickel on a carrier such as alumina or silica. The inner diameter d ₁ of the through hole 14 formed in the baffle plate 5 is larger than the outer diameter d ₂ of the catalyst support layer 10 (d ₁ > d ₂ ), and the difference between d ₁ and d ₂ is quite large.

Therefore, a fairly large gap is formed between the main tube 12 and the through hole 14, and the raw material gas 6 supplied from the trunk nozzle 7a passes through the gap in a short circuit, and the catalytic reaction does not proceed sufficiently. When the gas reaches the trunk nozzle 7b, a phenomenon called a so-called sheet pass occurs, resulting in a problem that the reaction heat recovery efficiency of the generated gas 8 is reduced. Furthermore, since the heat exchanger tubes 4 are not sufficiently restrained by the baffle plates 5, there is also the problem that the heat exchanger tubes 4 vibrate during operation. In order to improve these points,
The inner diameter d ₁ of the through hole 14 is set to be approximately the outer diameter of the main pipe 12, and the main pipe 12 is inserted into the through hole 14, and both ends thereof are fixed to the fixing plate 3.
It is also conceivable to form the catalyst support layer 10 in the remaining portions excluding the portions inserted into the through holes 11 and 14 after fixing to the holes 11 and 3b. However, even if it is possible to prevent the so-called sheet pass phenomenon, it is inconvenient that the heat exchanger tubes 4 cannot be replaced individually.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a catalyst layer-coated heat exchanger tube that facilitates maintenance and inspection of the heat exchanger tube on which a catalyst support layer is formed in a multi-tube reactor. be.

[Means for Solving the Problems] The gist of the present invention is that the outer diameter of the heat exchanger tube at the portion passing through the fixing plate and the baffle plate is formed larger than the outer diameter of the heat exchanger tube at the remaining portion. It is something.

[Function] The function of the present invention will be explained using embodiment drawings.
FIG. 1 is a partially enlarged sectional view showing an embodiment of the present invention. In the heat exchanger tube 4 of the present invention, the fixing plate 3
The insertion portions 15 and 16 of the baffle plate 5 and the baffle plate 5 are formed with a larger diameter than the outer diameter of the main pipe 12, and this portion is hereinafter referred to as the enlarged diameter portion. The outer diameters d ₃ and d ₄ of the enlarged diameter portions 15 and 16 are equal to each other, and the outer diameters d ₃ and d ₄ are larger than the outer diameter d ₂ of the catalyst support layer 10 (d ₃ = d ₄ > d ₂ ) is formed. The enlarged diameter portion 15 is the through hole 11 of the fixing plate 3a (or fixing plate 3b).
The inner diameter of the through hole 11 is the outer diameter of the enlarged diameter portion 15 because it is inserted through the hole and fixed by welding at the welded portion 13.
It is formed to a size approximately equal to d ₃ . On the other hand, since the expanded diameter portion 16 is inserted through the through hole 14 of the baffle plate 5, the inner diameter d ₁ of the through hole 14 is formed to be approximately equal to the outer diameter d ₄ of the expanded diameter portion 16. or slightly larger (at least to the extent that the short pass phenomenon does not occur).

By adopting the configuration described above, the main pipe 1
Even after forming the catalyst supporting layer 10 on the outer surface of the reactor 1, it is possible to assemble the reactor 1 by inserting the heat transfer tubes 4 through the holes 11 of the fixing plates 3a and 3b and the holes 14 of the baffle plate 5. becomes. This also applies during maintenance, inspection, and repair; for example, even if a situation arises in which one (or more) heat exchanger tubes 4 must be replaced, the heat exchanger tubes 4 can be replaced individually. can. Further, since the gap between the heat exchanger tube 4 and the through hole 14 becomes minute, problems such as short pass phenomenon and vibration are eliminated.

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

[Example] Refer to FIG. 1 and FIG. 3 again. Although the main parts of the present invention are shown in FIG. 1, the basic structure of the multi-tubular reactor to which the present invention is applied is the same as the reactor 1 shown in FIG. 3. However, the heat transfer tube 4 consists of a main tube 12 and a catalyst support layer 10 inserted into the outer surface of the main tube 12, and the main tube 12 has an enlarged diameter portion 15 inserted into the through hole 11 of the fixed plate 3a. and an enlarged diameter portion 16 that is inserted into the through hole 14 of the baffle plate 5. The outer diameters d ₃ and d ₄ of the enlarged diameter portions 15 and 16 are equal to each other, and
d ³ and d ₄ are formed to be larger than the outer diameter d ₂ of the catalyst support layer 10 (d ₃ , d ₄ >d ₂ ). The enlarged diameter portion 15 is inserted into the through hole 11 and fixed by welding at the welded portion 13. Although FIG. 1 only shows the vicinity of the part where one end of the heat exchanger tube 4 is fixed to the fixing plate 3a, the same applies to the attachment structure between the other end of the heat exchanger tube 4 and the fixing plate 3b.

On the other hand, the baffle plate 5 has a through hole 14 through which the enlarged diameter portion 16 can be inserted, and the inner diameter d ₁ of the through hole 14 is formed to be approximately equal to the outer diameter d ₄ of the enlarged diameter portion 16 or slightly smaller. (at least to the extent that the short pass phenomenon does not occur). By adopting such a configuration, when installing and fixing the heat transfer tube 4 coated with the catalyst support layer 10 in the reaction apparatus 1, the fixing plates 3a, 3b and the baffle plate 5 are attached to the reaction apparatus 1.
heat exchanger tubes 4 into the through holes 11 and 14.
It is possible to insert and install the In other words, when it becomes necessary to replace a part of the heat exchanger tubes 4 in use, it becomes possible to individually extract only the heat exchanger tubes 4 and replace them. In this way, the work for attaching and detaching the heat exchanger tubes 4 can be easily and reliably performed, and the workability of assembly, maintenance, inspection, and repair is greatly improved. Furthermore, when inserting the heat exchanger tube 4 into the through holes 11 and 14, the outer surface of the catalyst supporting layer 10 is inserted into the through holes 1.
Since it does not come into sliding contact with the inner walls of the catalyst support layer 10, damage to the outer surface of the catalyst support layer 10 is prevented, and therefore the catalyst support ability is not reduced. Furthermore, it is possible to prevent the occurrence of vibrations and a phenomenon called a so-called short pass.

Although the basic configuration of the present invention is as shown in FIG. 1, various specific methods for forming the enlarged diameter portions 15 and 16 can be adopted.

5 to 8 are cross-sectional views for explaining a specific method for forming the enlarged diameter portions 15 and 16.

First, in the formation method shown in FIG.
6a, 16b are partially flanged with a pipe upsetter, and each end 16a, 1 has an enlarged diameter.
By joining 6b to each other by welding 17, the heat exchanger tube 4 having the enlarged diameter portion 16 can be easily formed.

Next, in the forming method shown in FIG. 6, a cylindrical sheath tube 18 is inserted over each end of the pair of heat exchanger tubes 4a, 4b to be joined, and the sheath tube 18 is slid toward the right or left side in the drawing. The heat exchanger tubes 4a and 4b are fixed by welding at the welded portion 19, and the sheath tube 18 is slid back onto the welded portion 19 and fixed 20 to the heat exchanger tubes 4a and 4b by welding.
In this way, the sheath tube 18 fixed by welding can function as the enlarged diameter portion 16 of the heat transfer tube 4.

In addition, in the method example shown in FIG. 7, a pair of heat exchanger tubes 4
A tubular body 21 having a thick wall and a larger outer diameter than the heat exchanger tubes 4a and 4b is interposed between the heat exchanger tubes 4a and 4b, and each end of the heat exchanger tubes 4a and 4b is fixed by welding 22 to the tube body 21.

The forming method shown in FIGS. 5 to 7 described above has been disclosed as a means for forming the enlarged diameter portion 16 at the joint portion or the intermediate portion of the heat exchanger tube 4. The same can be applied to the case of forming the end enlarged diameter portion 15.

Next, the forming method shown in FIG.
5, and by performing weld overlay 23 on the end of the heat exchanger tube 4, the fixing plate 3a,
The outer diameter of the portion that is penetrated and fixed to 3b is expanded to form the expanded diameter portion 15. It goes without saying that the method of forming the enlarged diameter portions 15, 16 is not limited to the method shown in FIGS. 5-8.

[Effects of the Invention] As described above, according to the present invention, the outer diameter of the heat exchanger tube at the portion passing through the fixed plate and the baffle plate is made larger than the outer diameter of the catalyst support layer.
Not only does it become easier to insert the heat exchanger tube during assembly work, it also facilitates the replacement work of the heat exchanger tube for maintenance and inspection, and the surface of the catalyst support layer is prevented from being damaged. Furthermore, it is possible to prevent the occurrence of vibrations and a phenomenon called a so-called short pass.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, and FIG.
The figure is a cross-sectional view showing the general structure of a shell-and-tube heat exchanger type reactor, and FIG.
FIG. 4 is a sectional view showing a conventional heat exchanger tube mounting structure, and FIGS. 5 to 8 are sectional views illustrating a specific method for forming the enlarged diameter portions 15 and 16. DESCRIPTION OF SYMBOLS 1... Reactor, 2... Shell, 3a, 3b... Fixed plate, 4... Heat exchanger tube, 5... Baffle plate, 10... Catalyst support layer, 15, 16... Expanded diameter part.

Claims (1)

[Claims] 1 A pair of fixing plates are installed facing each other at both ends of a multi-tubular heat exchanger type reactor, which is made up of a plurality of heat exchanger tubes for passing heat exchange media whose outer walls are coated with a catalyst layer, arranged in a cylinder body. By fixing both ends of the heat transfer tube through the fixing plate and providing a plurality of baffle plates between the fixing plates, heat transfer is promoted by the baffle plates in the multi-tubular heat exchanger type reactor. In the catalyst layer coated heat exchanger tube configured to form a gas flow path, the outer diameter of the heat exchanger tube at a portion penetrating the fixed plate and the baffle plate is formed to be larger than the outer diameter of the heat exchanger tube at the remaining portion. Features: Catalyst layer coated heat transfer tube.