JP2003024765A - Catalyst-filled reaction pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the operation and shutdown of a catalyst-filled reaction pipe with high frequency, without destroying granular catalysts filled in the reaction pipe. SOLUTION: A one-through reaction pipe 10 has a double-pipe structure and the inside of a reaction pipe 11 is not completely filled with the catalysts 12. A notched inner pipe 13 has a notched part in the whole circumference, and the width of the notched part is changed according to the temperature fluctuation due to the operation and the shutdown, thereby absorbing force applied to the catalyst 12 to prevent them from being destroyed. The notched part is sealed with a seal plate 14 to prevent a raw material gas 18 from entering into the inside of the notched inner pipe from the notched part.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a catalyst-filled reaction tube such as an externally heated steam reforming reactor which uses a hydrocarbon such as naphtha, LPG or natural gas as a raw material and has a catalyst in the reaction tube, and more particularly, The present invention relates to a structure that enables high-frequency operation / stop.

[0002]

2. Description of the Related Art Conventionally, in the production of city gas or hydrogen gas, a steam reforming reaction has been used in which a raw material gas obtained by mixing a hydrocarbon gas and steam is reformed to obtain city gas or hydrogen gas. . The steam reforming reaction is carried out using a catalyst-filled reaction tube filled with a granular catalyst.

FIG. 8 and FIG. 9 show schematic configurations of a typical catalyst-filled reaction tube, which is a one-through reaction tube and a double-tube reaction tube, respectively. 8 (a) and 9
FIG. 8A shows a sectional configuration perpendicular to the axial direction, and FIG.
FIG. 9B and FIG. 9B show a sectional configuration including the axis.
In the one-through type reaction tube shown in FIG. 8, a cylindrical reaction tube 1
All of the inside is filled with granular catalyst 2. In the double-tube reaction tube shown in FIG. 9, a cylindrical inner tube 3 having a diameter smaller than that of the reaction tube 1 is housed in the cylindrical reaction tube 1 with a common central axis, and the granular catalyst 2 is It is filled between the reaction tube 1 and the inner tube 3. In the one-through type reaction tube of FIG. 8, the source gas 8 is introduced from one side in the axial direction and the reaction gas 9 is taken out from the other side in the axial direction. In the double-tube reaction tube shown in FIG. 9, the raw material gas 8 is provided in the gap between the reaction tube 1 and the inner tube 3 from one side in the axial direction.
Is introduced and the reaction gas 9 is taken out from the other side in the axial direction, is folded back at the other side in the axial direction, is introduced into the inner pipe 3, and the reaction gas 9 is taken out from one side in the axial direction of the inner pipe 3.

As a prior art relating to a catalyst-filled reaction tube, a proposal for increasing the thermal efficiency with a double-tube reaction tube is disclosed in Japanese Patent Laid-Open No.
1-83602, JP-A 06-219704, JP-A 06-263401 and the like.

[0005]

The improvement of thermal efficiency in the above-mentioned prior art and the like has been proposed on the premise of continuous operation. It may be possible to improve the overall efficiency by shutting down the operation when the reaction is not needed. However, the following problems must be solved in order to perform high-frequency operation / stop of the current catalyst-filled reaction tube.

1) Problems In a catalyst-filled reaction tube for an externally heated steam reforming reaction having a catalyst 2 in a reaction tube 1 using a hydrocarbon such as naphtha, LPG or natural gas as a raw material gas 8, 8 and FIG. 9, the reaction tube 1 so far is not operated / stopped at high frequency because the catalyst 2 is cracked even if the operation is required.

That is, the catalyst 2 filled in the reaction tube 1 at the initial cold time becomes hot and expands together with the reaction tube 1 during operation. Then, when they stop, they reach normal temperature and contract. If this operation / stop is repeated frequently, the catalyst 2 cannot withstand the change and is eventually destroyed.

Therefore, until now, once the operating state was entered, when the reaction gas to be the product was not needed, it was not brought to a complete stop state (cold state) and a slight amount of fuel was burned without introducing the raw material gas. By maintaining the catalytic combustion type reaction tube at the operating state or at a temperature slightly lower than that,
The catalyst 2 is prevented from cracking without expanding or contracting the catalyst 2 due to the operation / stop. After this,
The one-through type reaction tube of FIG. 8 will be described as an example.

2) Description of crack generation mechanism (1) Initial cold state As shown in FIG. 10 (1), the reaction tube 1 having the diameter D is filled with the catalyst 2 without any gap.

(2) When the temperature reaches the initial operating state during operation, the temperature of the reaction tube 1 is higher than the temperature of the catalyst 2, and the temperature linear expansion coefficient of the reaction tube 1 is the catalyst 2
Bigger than that. Therefore, the diameter of the reaction tube 1 is D +
It becomes ΔD, whereas that of catalyst 2 is smaller. As a result, the entire circumference between the reaction tube 1 and the catalyst 2 is shown in FIG.
A gap is created as in (2).

(3) End of operation When the operation is continued in the state of the item (2), the catalyst 2 in the reaction tube 1 moves in the axial direction of the reaction tube 1, and as shown in FIG. 10 (3). There is no gap in. At this time, the catalyst 2 is (1)
Since the initial cold of item, the gap has been filled, the state has changed to a consolidated state.

(4) During re-cooling When the operating state is changed to the cold state, the temperature change and shrinkage of the reaction tube 1 and the catalyst 2 are the same as when changing the state from (1) to (2). The contraction amount of the tube 1 is larger than that of the catalyst 2. Therefore, as shown in FIG.
A compressive force corresponding to the difference in contraction amount between the reaction tube 1 and the catalyst 2 is applied from the reaction tube 1.

(5) When the destruction operation / stop of the catalyst is repeated, the changes of the above (1) to (4) are repeated, and the consolidation of the catalyst 2 progresses in the gap generated in the state of (3), and (3) From the change from (4) to (4), the compression force applied to the catalyst 2 increases due to the progress of consolidation, which is the catalyst 2
It will be destroyed when it exceeds the destruction strength of.

An object of the present invention is to provide a catalyst-filled reaction tube which can be operated and stopped at high frequency without destroying the granular catalyst.

[0015]

According to the present invention, a one-through type catalyst packing in which a granular catalyst is packed in a reaction tube, a raw material is introduced from one side in the axial direction, and a reaction product is discharged from the other side in the axial direction. In the reaction tube, (a) a cylindrical inner tube having the same central axis as the reaction tube is inserted into the reaction tube, and (b) a part of the entire circumference of the inner tube is cut out.
(C) A seal plate that is easily expandable and contractable is attached to the notched portion of the entire circumference of the inner pipe, and (d) the inner pipe is closed at the end of the notched inner pipe on the side where the raw material enters in the axial direction. A catalyst-filled reaction tube having a structure in which a flat plate is attached, and (e) the catalyst is filled in the gap between the reaction tube and the inner tube.

According to the present invention, a cylindrical inner tube having the same central axis as that of the reaction tube is inserted into the reaction tube of the one-through type catalyst-filled reaction tube, and a granular material is formed in the gap between the reaction tube and the inner tube. Of the catalyst. Since a part of the entire inner circumference of the inner pipe is cut out, expansion and contraction due to temperature change are absorbed by the change in cutout width, and it is possible to prevent the generation of force that destroys the catalyst. This enables high-frequency operation / stop without destroying the granular catalyst. Since a seal plate that can easily expand and contract is attached to the notched part,
It is possible to prevent the raw material from entering the inside of the inner pipe through the notched portion. Since a flat plate that closes the inner pipe is attached to the raw material inlet side of the inner pipe, it is possible to prevent the raw material from entering the inner pipe that is not filled with the catalyst.

Further, according to the present invention, a cylindrical inner tube having the same central axis as the reaction tube is inserted into the reaction tube, and a granular catalyst is filled in a gap between the reaction tube and the inner tube, Into the gap with the inner pipe, the raw material is introduced from one side in the axial direction, the reaction product is led out from the other side in the axial direction, and the reaction product is further introduced into the inner pipe from the other side in the axial direction so that one side in the axial direction. In the double-tube reaction tube derived from (a), a part of the entire circumference of the inner tube is cut out, and (b) a part of the entire circumference of the inner tube is expanded and contracted. It is a catalyst-filled reaction tube having a structure in which an easy seal plate is attached.

According to the present invention, a cylindrical inner tube having the same central axis as the reaction tube is inserted into the reaction tube outside the double-tube catalyst-filled reaction tube, and the reaction tube and the inner tube are connected to each other. The granular catalyst is filled in the gap. Since a part of the entire inner circumference of the inner pipe is cut out, expansion and contraction due to temperature change are absorbed by the change in cutout width, and it is possible to prevent the generation of force that destroys the catalyst. This enables high-frequency operation / stop without destroying the granular catalyst. Since a seal plate that can be easily expanded and contracted is attached to the notched portion, it is possible to prevent the raw material and the like from flowing inside and outside the inner pipe.

Further, in the present invention, the seal plate is bent so that (a) the cross-sectional shape perpendicular to the axial direction has a U-shape, and (b) the concave portion having the U-shape cross-section. The side extends inward in the radial direction, the opening side is joined between both ends of the notched portion of the entire circumference of the inner pipe, and the catalyst enters the concave side of the U-shaped cross section of the seal plate. In order to prevent this, a catalyst intrusion prevention plate covering the opening side is provided.

According to the invention, in the notched portion of the entire circumference of the inner pipe, a seal plate bent so that the cross-sectional shape perpendicular to the axial direction has a U-shape, The recess side extends inward in the radial direction, and the opening side is joined and attached to both end pipes of the notched portion of the inner pipe. Since the seal plate is bent, it is possible to follow the change in the length of the cutout portion due to the expansion and contraction of the inner tube due to heat, and close the cutout portion. Since the opening side of the seal plate is covered with the catalyst intrusion plate prevention plate, it is possible to prevent the granular catalyst from invading the concave portion of the bent seal plate.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a one-through type reaction tube 10 as a catalyst-filled type reaction tube which is an embodiment of the present invention.
2 shows a schematic configuration of. 1A shows a sectional structure perpendicular to the axial direction, and FIG. 1B shows a sectional structure including the axial line. In the one-through type reaction tube 10 shown in FIG. 1, a granular catalyst 12 is filled in a cylindrical reaction tube 11. However, unlike the conventional one-through type reaction tube shown in FIG.
The entire interior of the reaction tube 11 is not filled with the catalyst 12, but the catalyst 12 is filled in the gap between the reaction tube 11 and the notched inner tube 13. As shown in FIG.
The cutout inner tube 13 is provided with a cutout at only one location on the entire outer circumference thereof. A seal plate 14 which can be easily expanded and contracted is attached to the cutout portion so as to block the granular catalyst 12 so as not to enter the inside of the cutout inner tube 13. Figure 1
As shown in (b), a flat plate 15 is attached to close one side of the notched inner tube 13 in the axial direction. Raw material gas 1
8 is introduced into the gap between the reaction tube 11 and the notched inner tube 13 from one axial direction where the flat plate 15 is attached, and is taken out as a reaction gas 19 from the other axial direction.

FIG. 2 shows a schematic structure of a double-tube reaction tube 20 as a catalyst-filled reaction tube which is another embodiment of the present invention. FIG. 2A shows a cross-sectional structure perpendicular to the axial direction,
FIG. 2B shows a sectional configuration including the axis. In the present embodiment, parts corresponding to those of the embodiment shown in FIG. 1 are designated by the same reference numerals, and redundant description will be omitted. The double-tube reaction tube 20 shown in FIG. 2 is different from the conventional double-tube reaction tube shown in FIG. 9 in that, as shown in FIG. There is a notch only in one place. A seal plate 14 which can be easily expanded and contracted is attached to the cutout portion so as to block the granular catalyst 12 so as not to enter the inside of the cutout inner tube 13.

FIG. 3 shows, as a further embodiment of the present invention, a sectional structure perpendicular to the axial direction which closes the notched portion of the notched inner tube 13 shown in FIGS. 1 and 2. In the present embodiment, the cutout portion is closed by the seal plate 24 that is bent so that the cross-sectional shape is U-shaped. The concave side of the U-shaped cross section extends in the radial direction of the notched inner tube 13, and both ends on the opening side are joined to both ends of the notched portion. A catalyst intrusion prevention plate 26 is attached to the surface of the seal plate 24 on the opening side so that the catalyst 12 does not enter the U-shaped cross section.

The one-through type reaction tube 10 shown in FIG. 1 and the double-tube type reaction tube 20 shown in FIG. 2 are flat plates 1 in which the notched inner tube 13 is closed by the one-through type reaction tube 10 in the axial direction.
Except for No. 5, the structure is basically the same, and the structure as shown in FIG.

1) Structure of the reaction tube 11 (1) As shown in FIG. 4 (2), a notched inner tube having a small diameter so that it can be installed inside the reaction tube 11 Produce 13. The thickness is 2 to 15 mm. Desirably, the thickness is in the range of 3 to 7 mm.

(2) As shown in FIG. 4C, a seal plate 14 which is a thin plate which is easily deformed is formed between both ends of the notched portion of the outer peripheral surface of the notched inner tube 13. Set with. The thickness of the seal plate 14 is 0.2 to 1.5 m
m, preferably 0.5 to 1.0 mm.

(3) Both ends of the set seal plate 14 are attached to the outer peripheral surface of the notched inner tube 13 by welding or the like over the entire length of the reaction tube 11 in the axial direction.

(4) The flat plate 15 is attached to one end of the notched inner tube 13 on the raw material entering side in the axial direction. this is,
As will be described later in (6), the raw material gas 18 enters the cavity inside the cutout inner tube 13 that is not filled with the catalyst 12,
This is to prevent it from flowing through the notch inner tube 13 as it is and mixing with the reaction gas 19 as a product.

(5) As shown in FIG. 4 (1), the seal plate 14 is attached as shown in item (3), and the notched inner tube 13 with the flat plate 15 attached as shown in item (4) is It is installed inside the reaction tube 11.

(6) The catalyst 1 is provided between the reaction tube 11 and the notched inner tube 13 to which the seal plate 14 and the flat plate 15 are attached.
2 while filling the inside of the cutout inner tube 13 with the catalyst 1
It is not filled with 2 and remains a cavity.

2) Example of the reaction tube 11 (1) Conditions: Shown in Table 1 below.

[Table 1]

Hereinafter, with reference to FIG. 5, the correspondence of the embodiment for the most severe reaction tube surface temperature maximum part will be shown.

(2) Specifications of the notched inner tube 13 to be adopted:
The results are shown in Table 2 below.

[Table 2]

(3) Change in the gap between the reaction tube 11 and the notched inner tube 13 when changing from the initial cold state to the operating state The gap between the reaction tube 11 and the notched inner tube 13 which was 12 mm in the initial cold state is As shown in Fig. 5 (1),
Change to 2.43 mm. The packed catalyst 12 is
Since it seems that the gap between the reaction tube 11 and the notch inner tube 13 is filled during both the initial cold and operation, 0.43 mm of the increased gap changes from the initial cold to the operation, The filled catalyst 12 will be consolidated.

(4) Change from the time of operation to the time of recooling The diameter of the reaction tube 11 is D + ΔD during operation.
At the time of recooling shown in (2), it changes to D at the time of initial cooling.
At this time, the notched inner tube 13 reaches a recooling state while maintaining a gap of 12.43 mm with the reaction tube 11 during operation.
That is, the notch inner tube 13 is reduced in diameter by the amount ΔD of decrease in the diameter of the reaction tube 11, which corresponds by reducing the notch width. In this way, when shifting from the time of operation to the time of recooling, the notch inner tube 13 keeps the filling width of the catalyst 12 constant by changing its diameter, in other words, the notch width.

(5) Changes in subsequent operation and cooling When the operation and stop are repeated thereafter, the operation of FIG.
The state of (1), the state of FIG. 5 (2) during cooling, changes the cutout width of the cutout inner tube 13 to δ and δ ′, thereby keeping the catalyst width of 12.43 mm and applying force to the catalyst 12. As a result, destruction of the catalyst 12 is prevented.

(6) Seal Plate Shape and Durability From the item (5), when the operation and stop are repeated, the seal plates 14 and 24 are repeatedly expanded and contracted, so that they are smoothly performed. Thus, it is preferable to use the U-shaped seal plate 24 whose shape is shown in FIG. Here, FIG. 6A shows a sectional structure perpendicular to the axial direction in a state in which the seal plate 24 is attached to the notched inner tube 13 by forming the welded portion 27, and FIG.
(B) shows a detailed sectional shape of the seal plate 24.

If the width of the U-shaped seal plate 24 changes due to operation / stop, its durability becomes a problem. Table 3 below shows the specifications of the U-shaped seal plate 24.

[Table 3]

According to a separate calculation, the number of repeatable times is 2,
It will be 6000 times. This means that, for example, if the vehicle is to be operated / stopped every day, it will be a little over 7 years, and the intended purpose will be fully achieved.

(7) Measures to prevent catalyst from entering the concave portion of the U-shaped seal plate 24. As shown in FIG. 7A, when the U-shaped seal plate 24 is used as it is, Catalyst 1 in the V-shaped recess
2, the seal plate 24 cannot be freely deformed.

Therefore, as shown in FIG. 7B, the catalyst intrusion prevention plate 26 is installed so as to face the concave portion having a U-shaped cross section. The catalyst intrusion prevention plate 26 has a thickness of 2 to 10
mm, preferably 2-5 mm. At this time, one side of the catalyst intrusion prevention plate 26 is attached to the outer peripheral surface of the notched inner cylinder 13 by the intermittent or continuous welding portion 27 in the axial direction of the reaction tube 11.

3) Scope of application The present invention can be applied to all reactors using the reaction tube 11 filled with the catalyst 12, and one available example is as follows. City gas production equipment High-purity hydrogen generation equipment High-purity carbon monoxide generation equipment Hydrogen generation equipment for fuel cells Ammonia production equipment

In particular, the demand for hydrogen will increase in the future, and it is expected to install a hydrogen generator including a catalyst-filled reaction tube in a home or a stand for supplying hydrogen to a hydrogen automobile. Since such a hydrogen generator is required to be repeatedly operated and stopped frequently according to demand, the utility of the present invention is expected to increase.

[0044]

As described above, according to the present invention, the reaction tube of the one-through type catalyst-filled reaction tube has the same central axis as the reaction tube and a part of the entire inner circumference is cut away. A cylindrical inner tube is inserted, and a granular catalyst is filled in the gap between the reaction tube and the inner tube. Expansion and contraction due to temperature changes are absorbed by changes in the notch width of the inner tube, and the force applied to the granular catalyst is mitigated, so high-frequency operation / stop is possible without destroying the catalyst.

Further, according to the present invention, in the reaction tube outside the double-tube catalyst-filled reaction tube, a cylinder having the same central axis as the reaction tube and a part of the entire inner circumference is cut out A cylindrical inner tube is inserted, and a granular catalyst is filled in the gap between the reaction tube and the inner tube. Expansion and contraction due to temperature changes are absorbed by changes in the notch width of the inner tube, and the force applied to the granular catalyst is mitigated, so high-frequency operation / stop is possible without destroying the catalyst.

Further, according to the present invention, the notched portion of the entire circumference of the inner pipe is closed with the sealing plate which is bent so that the sectional shape perpendicular to the axial direction is U-shaped. It is possible to follow the change in the length of the cutout portion due to expansion and contraction due to heat. Since the opening side of the seal plate is covered with the catalyst intrusion plate prevention plate, it is possible to prevent the granular catalyst from invading the concave portion of the bent seal plate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a one-through type reaction tube 10 which is an embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration of a double-tube reaction tube 20 which is another embodiment of the present invention.

FIG. 3 is a cross-sectional view when a U-shaped seal plate 24 is used as still another embodiment of the present invention.

FIG. 4 shows a reaction tube 11 and a notched inner tube 13 in each embodiment.
FIG. 6 is a cross-sectional view showing a process of assembling and filling the catalyst 12.

FIG. 5 is a cross-sectional view showing a state in which destruction of the catalyst 12 is prevented by the notch inner tube 13 in each embodiment.

FIG. 6 is a cross-sectional view showing a mounting structure of the U-shaped seal plate 24 shown in FIG. 3 to the notched inner tube 13.

7 is a cross-sectional view showing the effect of attaching a catalyst intrusion prevention plate 26 to the U-shaped seal plate 24 shown in FIG.

FIG. 8 is a cross-sectional view showing a schematic configuration of a conventional one-through type reaction tube.

FIG. 9 is a sectional view showing a schematic configuration of a conventional double-tube reaction tube.

FIG. 10 is a cross-sectional view showing changes in the operating state of the one-through type reaction tube of FIG.

[Explanation of symbols]

10 One-through type reaction tube 11 reaction tubes 12 catalyst 13 Notched inner tube 14,24 Seal plate 15 flat plate 18 Raw material gas 19 Reaction gas 20 Double-tube reaction tube 26 Catalyst intrusion prevention plate 27 Continuous weld

Claims (3)

[Claims] 1. A one-through type catalyst-filled reaction tube in which a granular catalyst is filled in a reaction tube, a raw material is introduced from one side in the axial direction, and a reaction product is led out from the other side in the axial direction, wherein: A cylindrical inner tube having the same central axis as that of the reaction tube is inserted into the reaction tube, and (b) a part of the entire circumference of the inner tube is cut away, and (c) the entire circumference of the inner tube. A seal plate that is easily expandable and contractible is attached to the notched portion, (d) a flat plate that closes the inner pipe is attached to the end of the notched inner pipe on the raw material entering side in the axial direction, and (e) the catalyst is Filled in the gap between the reaction tube and the inner tube,
A catalyst-filled reaction tube having a structure. 2. A cylindrical inner tube having the same central axis as that of the reaction tube is inserted into the reaction tube, and a granular catalyst is filled in a gap between the reaction tube and the inner tube to form the reaction tube and the inner tube. Into the gap of, the raw material is introduced from one side in the axial direction, the reaction product is led out from the other side in the axial direction, and the reaction product is further introduced into the inner tube from the other side in the axial direction and is led out from the one side in the axial direction. In the double-tube type reaction tube, which is (a) a part of the entire circumference of the inner tube is cut out, and (b) a seal that is easily expanded and contracted in the notched part of the entire circumference of the inner tube. A catalyst-filled reaction tube having a structure to which a plate is attached. 3. The seal plate is bent so that (a) the cross-sectional shape perpendicular to the axial direction has a U-shape, and (b) the concave side of the U-shaped cross-section has a radial direction. Of the inner pipe is joined to both ends of the notched portion of the entire circumference of the inner tube to prevent the catalyst from entering the concave side of the U-shaped cross section of the seal plate. The catalyst-filled reaction tube according to claim 1 or 2, further comprising a catalyst intrusion prevention plate that covers the opening side.