JP2002301355A - Method for withdrawing solid material from multiple- tubular reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely and sanitarily withdraw a solid material inside a multiple- tubular reactor. SOLUTION: This method for withdrawing a solid material 90 with which reaction tubes 20 of a multiple-tubular reactor 1 are packed, comprises: a stage (a) for inserting a suction pipe 30 connected to an evacuation/suction device 70 into each of the reaction tubes 20 through its one open end; and a stage (b) for sucking the solid material 90 within each of the reaction tubes 20, together with an air stream, through the front end of the suction pipe 30 and withdrawing the solid material 90 from the reaction tube 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extracting solids filled in individual reaction tubes of a multitubular reactor, such as catalysts used for catalytic reaction of hydrocarbons. I have.

[0002]

2. Description of the Related Art In the field of petrochemical industry, many catalytic reactions such as oxidation reaction, ammoxidation reaction, decomposition reaction, reduction reaction and reforming reaction of hydrocarbons using a tubular reactor are carried out. The reactors used for these reactions are packed with catalysts and inert packings suitable for the respective catalytic reactions. Specifically, the following techniques are known. Japanese Patent Application Laid-Open No. 2000-1484 discloses that a reaction tube containing vanadium as an essential component, a plurality of types of catalysts having different compositions, and catalytic vapor-phase oxidation of 1,2,4,5-tetraalkylbenzene to form anhydrous pyro A method for producing melitic acid is shown.

[0003] Japanese Patent Application Laid-Open No. 9-323950 discloses that a catalyst containing molybdenum, bismuth and iron as essential components, the activity of which is controlled by changing the mixing ratio of inert Raschig rings, is charged into a reaction tube, and isobutylene and / or A method for producing methacrolein by subjecting at least one selected from t-butyl alcohol to catalytic vapor phase oxidation is disclosed. Japanese Patent Publication No. 3-57906 discloses that a catalyst containing phosphorus and vanadium as essential components, whose activity is controlled by changing the mixing ratio of inactive alumina pellets, is charged into a reaction tube, and n-butane is subjected to catalytic gas phase oxidation. To produce maleic anhydride.

Japanese Patent Application Laid-Open No. 11-130722 discloses an inert substance-filled layer between a packed layer of a first-stage catalyst containing molybdenum, bismuth and iron as essential components and a second-stage catalyst containing molybdenum and vanadium as essential components. With
A method for producing acrylic acid from propylene by a two-stage catalytic gas phase oxidation method using one multitubular heat exchange reactor is shown. Since the catalyst used for these catalytic reactions generally decreases in activity and mechanical strength due to poisoning, caulking, sintering, etc. during use for a certain period of time,
Each time it is withdrawn from the reactor and replaced with fresh catalyst.

[0005] When the catalyst is replaced, a method of extracting solid materials such as the catalyst from the reactor is as follows. An operator enters the inside of the reactor and a thin metal or the like is formed upward from the lower opening of the reaction tube. A method of dropping solids inside the reaction tube while pushing up with a stick is adopted. Also, in US Pat. No. 5,228,484, a nozzle is inserted into the inside of the reaction tube from the upper end, high-pressure air is blown out from the tip of the nozzle, and the catalyst filled in the reaction tube is loosened or flowed with the high-pressure air. A technique is disclosed in which the catalyst is lifted up to the upper end of the reaction tube, sent to a filling chamber provided at the upper end of the reaction tube, and the filling chamber is evacuated to exhaust the catalyst.

[0006]

In the above-mentioned conventional method of extracting solids using a push-up rod, every time the rod is pushed up, solids such as a catalyst inside the reaction tube and their crushed materials fall and fall. The work environment is inferior for workers due to scattering of objects on the floor and generation of a large amount of dust. In addition, these falling objects and dust are often harmful to the human body, and therefore, workers engaged in extraction work must wear protective equipment such as dustproof clothes, goggles, dustproof masks, and gloves.

Furthermore, since the catalyst used in these catalytic reactions often contains expensive metals and the like in a high concentration, the extracted waste catalyst may be subjected to a treatment for recovering the metals and the like. However, Japanese Unexamined Patent Application Publication No. 11-130722 discloses
In the case of a reactor in which a plurality of types of catalysts and inactive substances are filled in a reaction tube as described in Japanese Patent Application Publication No. H10-157, these catalysts and inactive substances dropped from the reaction tube are mixed by a conventional extraction method, Separation and recovery of the catalyst takes a great deal of time. In industrial practice, a tubular reactor usually has hundreds to tens of thousands of reaction tubes, and withdrawing solids such as a catalyst in these reactors by a conventional method is a matter of extraction operation. Not only is the physical and emotional distress to workers engaged in employment, but also adverse for the environment.

In the above-described method using high-pressure air, the problem of dust generation is reduced because the filling chamber is disposed at the upper end of the reaction tube. Airtightness is required. Since the high-pressure air nozzle fed into the reaction tube passes through the filling chamber, airtightness at the penetrating portion also becomes a problem. These airtight structures become complicated, and a mechanism for both supply of high-pressure air and vacuum evacuation is required. Therefore, the size of the apparatus becomes large and workability is not very good. An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method for safely and hygienically and efficiently extracting solids in a multitubular reactor.

[0009]

SUMMARY OF THE INVENTION The present invention provides a method for extracting solids filled in a reaction tube of a multitubular reactor,
Step (a) of inserting a suction tube connected to an exhaust suction device from the end of the reaction tube, and solids in the reaction tube,
(B) drawing out solids from the reaction tube by sucking together with an air flow from the tip of the suction tube, and (b) extracting solids from the multitubular reactor. [Multi-tubular reactor] A multi-tubular reactor used in ordinary chemical product manufacturing or processing technology is used.
For example, Japanese Patent Application Laid-Open Nos.
No. 108525, JP-A-59-39342,
JP-A-59-82943, JP-A-62-1216
44, JP-A-5-125010,
The technology disclosed in JP-B-73674 can be applied.

In general, the reaction tubes used are arranged vertically, but those arranged horizontally or obliquely as disclosed in Japanese Patent Application Laid-Open No. Hei 9-141083. May be used. There is no particular limitation on the material of the reaction tube, and materials commonly used for contact reactions, such as stainless steel and carbon steel, can be employed. The inner diameter D of the reaction tube is 10 mm to 60 mm, preferably 15 mm to 5 mm.
0 mm, more preferably 20 mm to 40 mm. The reaction tube is generally linear and has the same diameter over the entire length, but a tube having a curved shape or a diameter varying in the axial direction is also used.

[Reaction] If the reaction is carried out in a multitubular reactor by filling a reaction tube with a solid substance such as a catalyst, the reaction can be applied to a usual contact reaction and other chemical treatment reactions. JP-A-2000-1484 and JP-A-9-32395 described above.
0, Japanese Patent Publication No. 3-57906,
It can be applied to the reaction disclosed in 130722. The reaction fluid is gas, solution, emulsion, etc.
The form used in a usual multitubular reactor is used.

[Solids] The solids in the reaction tube include solids used in various reactions using a multitubular reactor and deposits formed in the reaction tube when various reactions are performed. Is not particularly limited. Specific examples include various types of catalysts for catalytic reactions, inert substances, and adhering substances such as carbides. The catalyst for the catalytic reaction is a catalyst generally used for an oxidation reaction, an ammoxidation reaction, a decomposition reaction, a reduction reaction, a reforming reaction, and the like of hydrocarbons, but is not limited thereto.

The inert substance is used as a support for supporting the catalyst when filling the catalyst into the tubular reactor, a heating or cooling material for the reaction fluid, or a diluent for controlling the activity of the catalyst. , A substance which is inert to various catalytic reactions (raw materials and target products). For example, various ceramics such as alumina, silica, silica alumina, silicon carbide, silicon nitride, steatite and carbon steel,
Various metallic fillers such as stainless steel. As a catalyst, an inert substance, or a substance attached to the inner wall of the reaction tube,
There are products produced by contact reaction of trace amounts of impurities and carbides contained in the reaction fluid, and deposits such as scattering and sublimation from the catalyst components.

The catalyst and the inert substance are usually used in a granular form. The grain shape is not particularly limited, and may be any of a spherical shape, a cylindrical shape, a ring shape, an irregular shape, and the like. Regarding the particle size of the solid material to be extracted, for example, when the solid material is spherical or cylindrical, the diameter is defined as the diameter, and when the solid is ring-shaped, the outer diameter is defined as the particle size. The ratio S / D between the particle size S of the solid and the inner diameter D of the reaction tube is 0.5 or less, preferably 0.1%.
It is 45 or less, more preferably 0.4 or less. However, even if the above ratio is a solid matter larger than 0.5, this is not limited to the case where the solid matter can be crushed to 0.5 or less at the tip of the suction tube.

[Suction tube] The suction tube is generally of a circular cross section because it is easy for an operator engaged in withdrawing work to grasp and has good workability. What is necessary is just to select suitably according to the cross-sectional shape of a reaction tube. The suction tube may have high rigidity and is hardly deformed, or may have flexibility and can be bent. However, it is preferable to use a material having such a shape maintaining property as not to be crushed by a negative pressure at the time of exhaust suction. As for the material of the suction tube, the material made of polyethylene is easy to use because it bends moderately, but it is easy to use.
A resin material such as Teflon (registered trademark) or polyvinyl chloride or a metal material such as stainless steel or carbon steel can be used, and a plurality of these material layers can be laminated or spliced.

The material and shape of the suction tube may be different between a portion inserted into the reaction tube of the reactor and a portion extending outside the reaction tube. Further, the material and the shape structure may be different between the tip portion and the rear portion of the portion inserted into the reaction tube. The thickness T of the tube wall of the suction tube varies depending on the material and the required performance, but is usually T ≦ 5 mm, preferably 1 mm ≦ T ≦ 3 mm, and more preferably 1 mm ≦ T.
≦ 2 mm. [Exhaust Suction Apparatus] An exhaust suction apparatus is connected to the suction pipe for sucking solids together with airflow from the opening at the tip.

The structure and specifications of the exhaust suction device are the same as those of a generally used exhaust suction device. The exhaust suction device includes an exhaust pump driven by a power source such as a motor or an engine. As the mechanism and structure of the exhaust pump, those similar to the generally used exhaust pump can be adopted. The suction pipe is connected to the suction port of the exhaust suction device. The suction pipe may be directly connected to the exhaust suction apparatus, or the suction pipe and the exhaust suction apparatus may be connected by a pipe. A trap may be provided between the suction pipe and the exhaust pump to separate the air flow from the solid matter and collect only the solid matter. There is no particular limitation on the method of separating the solid matter extracted from the air flow, and a gravity type, centrifugal type, inertial classifier or a filter having a suitable aperture generally used for classification of the solid matter can be used. .

In order to prevent the fine powder and the like that could not be collected by the trap from being mixed into the exhaust pump, a collecting device such as a bag filter or a cyclone having an appropriate opening is provided between the trap and the exhaust pump. It is desirable to install in.
The capacity of the exhaust suction device, that is, the amount of intake air, depends on the size and specific gravity of the solid material to be extracted, the degree of adhesion of the solid material such as catalyst to the container, the pressure resistance of the suction pipe (the pressure inside the suction pipe is reduced. It is possible to use a device having an appropriate capacity after comprehensively judging the pipe resistance, the pipe resistance, the speed of extracting solids (the time required for extracting solids per reaction tube), and the like.

The exhaust suction device may be provided with a cooler or a silencer to reduce adverse effects on the environment. [Discharge of solids] In the case of a multi-tube reactor in which the reaction tubes are arranged vertically, the insertion position of the suction tube may be either from the upper opening or the lower opening of the reaction tube, and the structure of the reactor, etc. In consideration of the above, a method with good workability may be adopted. Generally, the workability is good, for example, the work posture is easier when inserted from the upper end opening of the reaction tube. When the tip of the suction tube is inserted through one of the openings of the reaction tube, and air in the reaction tube is sucked from the tip of the suction tube, an air flow is generated. When the tip of the reaction tube approaches the solid in the reaction tube, the solid is carried into the suction tube by the airflow at the tip of the reaction tube and is extracted from the reaction tube. At the tip of the reaction tube, air outside the reaction tube is sequentially supplied mainly through the gap between the inner wall of the reaction tube and the outer wall of the suction tube. By gradually inserting the tip of the suction tube toward the inside of the reaction tube together with the suction of the solid, the solid in the reaction tube can be sequentially extracted.

At this time, if the distance between the tip of the suction tube and the solid is too large, the speed of withdrawing the solid is reduced,
In some cases, solids cannot be extracted. Also, if the distance between the solid and the tip of the suction tube is extremely small, or if the gap between the inner wall of the reaction tube and the outer wall of the suction tube is small, the speed at which the solid is extracted decreases. In other words, by efficiently supplying air to the suction pipe, and by manipulating the position of the tip of the suction pipe so that the solid is located in or near the airflow at the tip of the suction pipe, the solid substance is removed. The extraction speed is improved. For example, such an effect can be obtained by devising the outer diameter of the suction tube to provide an appropriate gap between the inner wall of the reaction tube and the suction tube, and further processing the tip of the suction tube into an appropriate shape.

[Tip of Suction Tube] The gap between the inner wall of the reaction tube and the tip of the suction tube inserted into the reaction tube, ie, the ratio of the inner diameter D of the reaction tube to the outer diameter d ₁ of the suction tube tip is determined by the solid material. It has a great effect on the extraction speed. Specifically, 0.7 ≦
d ₁ /D≦0.95, preferably 0.72 ≦ d ₁ / D ≦
0.9, more preferably 0.75 ≦ d ₁ /D≦0.85
In this case, the extraction operation can be performed efficiently. D ₁ / D
The smaller the is, the larger the gap between the inner wall of the reaction tube and the suction tube, the more efficiently air outside the reaction tube is supplied to the tip of the suction tube, but the smaller the opening area inside the suction tube. d
_{If 1} / D is too small, not only the amount of solids extracted is reduced, but also the solids are liable to be clogged in the suction tube. If d ₁ / D is too large, the gap between the inner wall of the reaction tube and the suction tube becomes small, so that the air sucked from the outside of the reaction tube becomes small, it becomes difficult to extract solids, and the suction tube is inserted into the reaction tube. It becomes difficult or the frictional resistance between the inner wall of the reaction tube and the suction tube increases, making it difficult to insert the suction tube into the reaction tube.

The particle size S of the solid and the inner diameter d _{2 of the} suction tube
The ratio d ₂ / S also has a large effect on the speed of extracting solids. Specifically, d ₂ /S≧2.5, preferably d ₂ /S≧2.7, and more preferably d ₂ / S ≧ 3.
However, at this time, d ₂ must satisfy d ₁ −d ₂ × 2 <0. If the value of d ₂ / S is too small, the work efficiency is significantly reduced, for example, solids are hardly sucked into the suction tube or solids are easily clogged in the suction tube. The tip shape of the suction tube inserted into the reaction tube may be appropriately selected in consideration of the shape and size of the solid, the state of attachment to the reaction tube, and the speed of withdrawing the solid. It is preferable to select a shape in which the air flow at the tip of the suction tube can be efficiently used for extracting the solid material, since the solid material can be easily extracted together with the air flow, and the speed of extracting the solid material is improved.

For example, when a cylindrical suction tube is used,
The suction pipe may have a circular end face that is cut horizontally on a plane perpendicular to the pipe axis direction, or may be inclined at a certain angle θ with respect to a plane perpendicular to the pipe axis direction of the suction pipe. It may have an elliptical end face. In order to efficiently extract solids from the reaction tube, it is necessary to consider the relationship between the inclination angle θ and the solids extraction speed. Then, the present inventor examined the relationship between the inclination angle θ of the tip of the suction tube and the speed of extracting solids. As a result, as shown in FIG. 1, as the inclination angle is increased from θ = 0, the solid material extraction speed increases, but when the inclination angle exceeds a certain inclination angle θx, the solid material extraction speed tends to decrease. I found it.

Of course, the inclination angle θx at which the extraction speed becomes maximum varies depending on the intake amount of the exhaust suction device, the size of the solid matter in the reaction tube, and d ₁ / D described above. If it is excessively large, the speed at which solids are withdrawn decreases. As a result of the above examination, the present inventor has found that the inclination angle θ of the tip of the suction tube suitable for extracting solid matter is
As 0 ° ≦ θ ≦ 70 °, preferably 0 ° ≦
θ ≦ 60 °, more preferably 0 ° ≦ θ ≦ 50 °. The distal end of the suction tube may be provided with a recessed portion that is recessed from a plane perpendicular to the tube axis direction. Examples of the shape of the concave portion include a rectangular shape such as a wedge shape.

If the end face is inclined or has a concave portion, an appropriate gap is formed between the solid and the tip of the suction pipe, so that the air flow at the tip of the suction pipe can be efficiently reduced. It can be used for extracting material and can always maintain a stable air flow, and as a result, the speed of extracting solid material is improved. A protrusion may be provided on the outer periphery of the distal end of the suction tube. This convex portion is effective in maintaining a constant distance between the outer surface of the suction tube and the inner wall surface of the reaction tube. It also has the effect of improving the rigidity and deformation resistance of the suction tube. If the projections are arranged intermittently in the circumferential direction of the suction pipe, the air flow passing through the gap between the suction pipe and the reaction tube is less likely to be hindered. The convex portions may be spirally arranged.

At the tip of the suction tube, an adapter made of a metal such as stainless steel or carbon steel or a resin may be connected as a member separate from the rear portion. For example, when the solid material is larger than the inner diameter of the suction tube, or when the solid material is firmly attached to the inner wall of the reaction tube, it is difficult to remove the material using a suction tube made of a relatively soft material such as polyethylene. If an adapter made of a hard material such as is provided at the end of the suction tube, the solid can be finely crushed at the end of the adapter to perform extraction, so that the effect of improving extraction efficiency can be obtained. In the extraction process, the solids move at high speed in the suction pipe together with the air flow, and therefore, depending on the material of the suction pipe used and the pipes and exhaust suction device attached thereto, some of the solid matter may be charged with static electricity by friction. Since there is a danger of ignition or explosion due to static electricity depending on the solid matter extracted, it is preferable to connect a ground to an appropriate place for safety.

If the solid to be extracted is brittle and dust is remarkable, or if there is a danger of spontaneous ignition of the catalyst or substances adhering to the catalyst due to contact with oxygen, before the extraction operation is performed, The solid material may be wet-treated with a chemical such as water, a mineral oil mixed with various additives, or a surfactant. Specifically, the techniques disclosed in JP-A-50-140369 and JP-A-59-73038 can be applied. Further, a non-breathable plate may be laid in the reactor. Specifically, the technique disclosed in JP-A-61-35842 can be applied. [Operation and effect] Using a suction tube for extraction directly or indirectly connected to the exhaust suction device, insert the tip of the suction tube from any opening of the reaction tube, and suck solids together with the air flow. Then, no dust is generated in the work place, and the extraction work can be performed in an extremely favorable working environment. In addition, by appropriately setting the material, outer diameter, tip shape, and the like of the suction pipe for extraction, the efficiency of the extraction operation is improved, and the time for extracting solids can be reduced.

Further, when extracting solids from the opening on the upper end side of the reaction tube, by inserting the tip of the suction tube from the opening of the reaction tube to a desired position, only unnecessary solids in the reaction tube are selected. The extracted catalyst can be easily separated and recovered. For example, as described in Japanese Patent Application Laid-Open No. H11-130722, a reaction in which different types of catalysts and inert materials are filled in a plurality of reaction zones divided in a tube axis direction of a reaction tube to perform a reaction. In the reactor, only the catalyst packed in the upper reaction zone can be extracted. Specifically, in the conventional method, since the catalyst is extracted from the lower portion of the reaction tube, it is necessary to extract even the catalyst filled in the lower reaction zone which does not need to be extracted. By inserting the tip to a desired position in the reaction tube, only the catalyst filled in the upper reaction zone of the reaction tube can be selectively extracted.

The extraction method of the present invention is used not only for extracting solid matter such as a deteriorated catalyst from a multitubular reactor at the time of replacement of a filler such as a catalyst, but also for removing a reaction tube of the multitubular reactor. It can also be used for adjusting the filling amount of the filler when filling a new catalyst or an inert substance. When a catalyst or an inert substance is filled in a reaction tube in the industrial implementation of a catalytic reaction using a multitubular reactor, the amount of catalyst (filled bed height) filled in each reaction tube and each reaction due to the filling. One skilled in the art will appreciate that the pressure loss in the tube is preferably ideally uniform.

If the mass and volume of the catalyst and the like are accurately measured before filling the reaction tube with the catalyst and the like, the packed bed height and pressure loss of the catalyst and the like in each reaction tube after the filling should be constant. is there. However, in practice, the packed bed height and pressure loss in each reaction tube are different because there are slight differences in the shape and particle size of the catalyst and the like, and the filling speed of the catalyst and the like at the time of filling is not always constant. Will vary. As described above, in a multi-tube reactor having hundreds to tens of thousands of reaction tubes, the height of the packed bed of solids such as a catalyst and the pressure loss are packed so as to be uniform in all the reaction tubes. That takes a lot of effort.

Therefore, in practice, the packed bed height and the pressure loss are adjusted so as to fall within the range of a predetermined reference value in consideration of the catalyst performance and the performance of the equipment. At this time, after the filling, the reference value is deviated from the reference value, and the reaction tube in which the height of the catalyst packed bed is increased or the pressure loss is increased is taken out of the packed material, and the filling is performed again. At this time, if the extraction method of the present invention is used as a method for extracting a part of the filled catalyst, it is not necessary to extract all the filled catalyst, and the work of adjusting the height of the packed bed and the pressure loss can be efficiently performed.

[0032]

Next, embodiments of the present invention will be described in detail. [Multitubular reactor] As shown in FIG.
Is provided with a number of reaction tubes 20 erected in the vertical direction. The upper and lower ends of the reactor 10 have inlets and outlets 12 and 1 for the reaction fluid.
4 are provided. Doors 12, 14 of reactor 10
Are connected to the supply equipment of the reaction fluid, the processing equipment of the preceding step, the processing equipment of the next step, and the like, but are not shown. Further, the reactor 10 may be provided with the same mechanical equipment as the normal reactor 10, such as a temperature controller for heating and cooling the reaction fluid and a sensor device for monitoring the progress of the reaction. it can.

As shown in FIG. 3, the reaction tube 20 is filled with a granular catalyst 90 as a solid material.
After the reaction fluid passing through 0 comes into contact with the catalyst 90 and is catalyzed to cause a predetermined reaction, the reaction fluid is discharged from the reactor 10. When the operation of the reactor 10 is continued, the physical properties of the catalyst 90 change or by-products adhere to the surface of the catalyst 90, and when the function of the catalyst 90 is reduced, the catalyst 90 is taken out from the reaction tube 20, The fresh catalyst 90 is recharged. [Removal of catalyst] After discharging the reaction fluid from the reactor 10 or cleaning the inside of the reactor 10, the reaction tube 20
The operation of extracting the catalyst 90 from the inside is performed.

As shown in FIG. 2, the worker M
The upper end of the suction pipe 30 rises to the work floor where the upper end of the suction pipe 30 is opened, and the tip of the suction pipe 30 is arranged at the upper end of the reaction pipe 20, and the suction pipe 30 is inserted into the reaction pipe 20. The suction tube 30 is connected to the reactor 10
From the inlet / outlet 12 of the reactor 10 to the outside through a manhole provided at an arbitrary position of the reactor 10, and is connected to a solid trap device 40 installed outside the reactor 10 via a pipe 32. The solids trap device 40 separates only the solid catalyst 90 from the air stream. The solid matter trap device 40 further includes a bag filter 50, a cooler 60, an exhaust pump 70, a silencer 8 via a pipe 32.
Connected to 0. The exhaust pump 70 is a vacuum pump driven by a motor or the like, and forcibly exhausts the air in the pipe 32 to generate an air flow. The basic function of extracting solids by the suction pipe 30 and separating and recovering solids from the airflow by the solid trapping device 40 can be achieved only by the exhaust pump 70. However, the provision of the back filter 50, the cooler 60, and the silencer 80 is effective in preventing environmental pollution and improving the working environment.
Specifically, the bag filter 50 can capture and collect the fine dust that could not be captured by the solid matter trapping device 40 from the airflow. Cooler 60 is connected to piping 3
The air inside 2 can be cooled, and the overheated exhaust is prevented from being released. If the air flow in the pipe 32 is not so high, the cooler 60 may be omitted. The silencer 80
The noise generated by the airflow in the pipe 32 can be reduced.

The solids 90 separated and recovered from the air stream by the solids trapping device 40 can be discarded by a usual means, and useful resources can be recovered and reused. For example, when the solid 90 is a catalyst, it can be sent to a process for separating and recovering the contained metals. [Withdrawal work] In FIG. 2, one end of the suction pipe 30 connected to the solid trap device 40 via the pipe 32 is
It is drawn into the inside of the reactor 10, and the tip of the suction tube 30 is arranged at the upper end of the reaction tube 20.

As shown in detail in FIG. 3, air is sucked from the distal end of the suction tube 30. Connect the tip of the suction tube 30 to the reaction tube 2
0, the solids 90 are drawn by the flow of the air sucked into the suction pipe 30 when the solids 90 are placed on the solids 90 filled in the inside of the solids 9.
0 is also sucked into the suction tube 30. The solid matter 90 sucked into the suction pipe 30 is sent to the solid matter trapping device 40 via the above-described pipe 32, and is separated from the air flow and collected. When the solids 90 are sucked at the tip of the suction tube 30, the solids 9 in the reaction tube 20 correspond to the sucked solids 90.
Since the distance between the upper end of the suction tube 30 and the upper end of the suction tube 30 is large, the distal end of the suction tube 30 is inserted into the reaction tube 20 so as to approach the upper end of the solid 90.

If this operation is continued, the reaction tube 2
The solids 90 filled over the entire length of 0 can be withdrawn. If the further insertion is stopped with the suction tube 30 inserted halfway through the reaction tube 20, the solids 90 slightly below the distal end position of the suction tube 30 at that position are extracted, and The solids 90 below will remain filled. At this time, if the insertion depth of the tip of the suction tube 30 is adjusted, the solids 9 remaining in the reaction tube 20 can be adjusted.
It becomes possible to arbitrarily adjust the height of the packed bed of 0. The outer diameter of the suction tube 30 is equal to the inner wall of the reaction tube 20 and the suction tube 3.
The gap is set such that air outside the reaction tube 20 can be efficiently supplied to the distal end portion of the suction tube 30 between itself and the outer wall of the suction tube 30.

FIG. 4 shows several specific examples in which the tip structure of the suction tube is different. Fig. 4 (a)
Has a circular end face in which the distal end of the suction pipe 30 is cut along a horizontal plane orthogonal to the pipe axis direction. In FIG. 4B, the tip of the suction tube 30 is inclined at an inclination angle θ with respect to a horizontal plane orthogonal to the tube axis direction, and has an elliptical end surface. As compared with FIG. 4 (a), the substantial opening area is increased and the solid material 9
By forming an appropriate gap between 0 and the tip of the suction tube 30,
The solids 90 are easily sucked in with the air flow. The solid matter 90 contacting the tip of the suction pipe 30 is sucked into the suction pipe 30 while moving along the slope, so that the solid matter 90
Can be prevented from closing the opening while contacting the end surface.

In FIG. 4C, a U-shaped recessed portion 34 having an open end is provided at two diametrically opposed ends of the suction tube 30. Similar to the structure shown in FIG. 4B, the substantial opening area at the tip is increased, and the solid 90 and the suction pipe 3 are removed.
An appropriate gap is formed at the leading end of the zero. The provision of the plurality of recesses 34 allows the airflow and the solids 90 to be sucked in from the other recess 34 even when one of the recesses 34 is temporarily closed by the solid 90. In addition, since the solids 90 that block one of the recesses 34 are moved by the airflow or the force of the solids 90 passing through the other recess 34 and are sucked into the suction pipe 30, the clogging of the solids 90 is eliminated. Action also occurs.

In FIG. 4D, triangular wedge-shaped concave portions 34 are arranged in the circumferential direction. By providing a large number of recessed portions 34, the suction action can be exerted uniformly and efficiently in the circumferential direction. The solid matter 90 fixed inside the reaction tube 20 can be broken down with a sharp tip between the recessed parts 34 to facilitate suction. In FIG. 4 (e), elongated rectangular recesses 34 are arranged in the circumferential direction. Even if the distal end surface of the suction tube 30 is closed with a lump of the solid matter 90, a sufficiently large opening can be secured on the outer surface. In this case, if the width of the recess 34 is set to be larger than the particle size of the solid 90, the suction of the solid 90 from the recess 34 can be performed well.

In FIG. 4F, a spiral convex portion 36 is provided on the outer peripheral surface of the suction tube 30 by a predetermined length. When the outer peripheral end of the convex portion 36 abuts on the inner wall of the reaction tube 20, the reaction tube 2
A gap through which the air flow passes can be reliably provided between the suction pipe 30 and the suction pipe 30, and air can be efficiently supplied to the tip of the suction pipe. Even if the convex portion 36 is arranged over the entire circumference of the suction tube 30, if the spiral convex portion 36 is used, air can flow along the spiral, and the air flow is interrupted at the convex portion 36. There is no. [Adjustment of Filling Amount of Solid] FIG. 5 shows the height (amount) of the packed layer of the solid 90 filled in the reaction tube 20 using the suction tube 30.
FIG.

(A) shows a state in which the reaction tube 20a is filled with the solid matter 90 in an appropriate amount. The <MID> line indicates the height position of the proper filling amount. The range between the <MAX> line and the <MIN> line is an allowable range of the filling layer height. (b) shows a situation in which the height of the packed bed has become too high after the solid 90 is filled. The height of the packed bed of the solid material 90 is <M
AX> line is exceeded. Then, as shown in (c), the suction tube 30 is inserted from the upper end of the reaction tube 20b, and the solid matter 90 is extracted from the tip of the suction tube 30. As shown in (d), the tip of the suction tube 30 is set to <M> below the <MAX> line.
Position that does not fall below the IN> line, as much as possible <MID>
If it is inserted to a position close to the line, the upper end position of the solid matter 90 remaining in the reaction tube 20b will be <MID> around the <MID> line.
AX> line and <MIN> line are surely set.

Note that the <MAX> line, <MID>
If the distance from the <MIN> line to the upper end of the reaction tube 20b is measured or calculated, the insertion amount of the suction tube 30 into the reaction tube 20b may be adjusted according to the distance. <MAX>, <MID>,
If an instruction line corresponding to <MIN> is displayed, work can be easily performed using the instruction line as a guide. If a protrusion-shaped stopper is provided at a position corresponding to <MID> on the outer periphery of the suction tube 30 and the stopper is inserted to a position where the stopper is hooked on the upper end opening of the reaction tube 20b, the insertion depth of the suction tube 30 is reduced. Can be set easily and reliably.

There is also an allowable range of pressure loss after filling the reaction tube with the solids 90. Solids 90
With respect to the reaction tube 20 in which the pressure loss becomes higher than the upper limit after filling the solid, the solid 90 is drawn out by suction with the lower limit of the height of the packed bed, that is, the <MIN> line as the lower limit. It may be adjusted to be within the value. [Extraction of Solids Only in Specific Layer] The embodiment shown in FIG. 6 shows a method of extracting only solids 90 in the specific layer from the reaction tube 20.

The catalyst 90 is placed in the reaction tube 20 in order from the bottom.
c, an inert substance 90b for isolation and a catalyst 90a are filled. The catalyst 90c is filled from the lower end of the reaction tube 20 to a height C, on which an inert substance 90b is filled at a height B, and the catalyst 90a is filled at a height A at the top. Such a filling structure makes the reaction fluids come into contact sequentially,
The present invention is applied to a reaction method in which reactions by the respective catalysts 90a and 90c are continuously performed. The inert substance 90b is made of various metals, ceramics, or resins, and has a shape such as a ring or a sphere, and functions to reliably separate the catalysts 90a and 90c and to heat or cool the reaction fluid.

An operation of extracting only the catalyst 90a whose activity has been reduced from such a reaction tube 20 is performed. The suction tube 30 is arranged at the upper end of the reaction tube 20 to perform suction. The catalyst 90a filled in the upper part of the reaction tube 20 is sucked into the suction tube 30 together with the air and extracted. If the tip of the suction tube 30 is inserted to a position slightly higher than the depth A of the reaction tube 20, the entire catalyst 90a is extracted, and
The inert substance 90b and the catalyst 90c remain in the reaction tube 20. Thereafter, a new catalyst 90 is added to the reaction tube 20.
a or the regenerated catalyst 90a, the desired reaction process can be resumed.

After the above-described step of extracting the catalyst 90a, if only the inert substance 90b is extracted while leaving the catalyst 90c, the replacement of the inert substance 90b can be performed. In this case, if the catalyst 90a is recovered and removed from the solid substance trap device 40 at the stage when the removal of the catalyst 90a is completed, only the inert substance 90b is recovered in the solid substance trap device 40 in the next stage. . Furthermore, when extracting the catalyst 90c, the inert substance 90b collected in the solid substance trap device 40 is taken out, and then the catalyst 90c is withdrawn.
Only c is collected.

In this method, different types of solids 90 are used.
a, 90b and 90c can be separately separated and collected.

[0049]

Embodiments of the present invention will be specifically described below as an example of the present invention, in which a solid material such as a catalyst subjected to an oxidation reaction is extracted from a multitubular heat exchange reactor. However, the present invention is not limited to this. The average time required for extraction and the amount of dust generated in this embodiment are defined as follows. Average extraction time: Average time required to extract all solids from one reaction tube (seconds) Dust amount: After all solids were extracted from 100 reaction tubes,
Amount of dust adhering to the dust mask worn by the worker (mg) Dust amount = (dry weight of dust mask after extracting 100 reaction tubes)-(dry weight of dust mask before operation) -Example 1- A reaction for producing methacrylic acid from methacrolein was carried out according to the method described in Example 1 of JP-A-4-210937. The number of the reaction tubes was 10,000, and the length of the reaction tubes was 3000 mm.

After the reaction was continued for 8000 hours, the reaction tube was cooled, and the following extraction operation was performed. (Withdrawal work) One end of a suction tube made of a polyethylene tube having an outer diameter of 21 mm and an inner diameter of 18 mm was exhausted through a solid trap device through a solid substance trapping device, having a suction volume of 3.0 m ³ / min and an ultimate vacuum of 19,600 Pa. The pump was connected to an exhaust suction device connected. The tip of the suction tube on the side to be inserted into the reaction tube was processed into a horizontal end face shape as shown in FIG.

An extraction suction tube was gradually inserted from the upper opening of the reaction tube toward the lower portion of the reaction tube, and all the catalyst filled in the reaction tube together with air was extracted. This extraction operation was performed for a total of 100 reaction tubes.
The average extraction time was 22 seconds. The amount of dust was 91 mg. -Comparative example 1- In Example 1, the extraction operation was performed on 100 reaction tubes in the same manner as in Example 1 except that the extraction operation described below was performed.

(Pull Out Work) A piano wire of 4 mm × 2 mm square and 4500 mm long was prepared. One end of the piano wire was inserted from the lower opening of the reaction tube, and all the solids such as the catalyst in the reaction tube were gradually dropped and pulled out while being pushed up toward the upper portion of the reaction tube. During the extraction work, dust is generated very much, and in order to protect the body from falling objects, workers wear not only a dust mask but also a cotton hood, dust clothes, helmet, goggles and gloves. Did the work. The average time required for extraction was 40 seconds, and the amount of dust was 1594 mg. -Example 2 With the exception of using a suction tube made of a polyethylene tube having an outer diameter of 18.5 mm and an inner diameter of 15 mm in Example 1, 100 reaction tubes were extracted in the same manner as in Example 1.

The average time required for extraction was 30 seconds, and the amount of dust was 87 mg. -Example 3-An extraction operation was performed on 100 reaction tubes in the same manner as in Example 1 except that a suction tube formed of a polyethylene tube having an outer diameter of 23 mm and an inner diameter of 18 mm was used. The average extraction time is 28 seconds and the amount of dust is 87
mg. -Example 4 With the exception that a suction tube made of a polyethylene tube having an outer diameter of 17 mm and an inner diameter of 15 mm was used in Example 1, extraction was performed on 100 reaction tubes in the same manner as in Example 1.

The average time required for extraction was 42 seconds, and the amount of dust was 80 mg. -Example 5- The same operation as in Example 1 was performed except that a suction tube formed of a polyethylene tube having an outer diameter of 24.5 mm and an inner diameter of 18 mm was used. The average time required for extraction was 40 seconds, and the amount of dust was 77 mg. -Example 6-The same operation as in Example 1 was performed, except that a suction tube made of a polyethylene tube having an outer diameter of 21 mm and an inner diameter of 14 mm was used, and extraction was performed on 100 reaction tubes.

The average time required for extraction was 33 seconds, and the amount of dust was 85 mg. -Example 7-The same operation as in Example 1 was performed, except that a suction tube made of a polyethylene tube having an outer diameter of 21 mm and an inner diameter of 12 mm was used, and extraction was performed on 100 reaction tubes. The average extraction time is 58 seconds and the amount of dust is 93
mg. -Example 8-In Example 1, a suction tube for extraction was used in which the tip of the suction tube on the side to be inserted into the reaction tube was machined to the inclined end surface (inclination angle θ = 45 °) shown in FIG. Except for the above, extraction operation was performed on 100 reaction tubes in the same manner as in Example 1.

The average time required for extraction was 18 seconds, and the amount of dust was 90 mg. -Example 9-In Example 1, a suction tube for extraction was used in which the tip of the suction tube to be inserted into the reaction tube was machined to the inclined end surface (inclination angle θ = 65 °) shown in FIG. Except for the above, extraction operation was performed on 100 reaction tubes in the same manner as in Example 1.
The average extraction time was 25 seconds, and the amount of dust was 84 mg. -Example 10-In Example 1, a suction pipe for extraction was used in which the tip of the suction pipe on the side to be inserted into the reaction tube was machined to the inclined end face (inclination angle θ = 75 °) shown in FIG. Except for the above, extraction operation was performed on 100 reaction tubes in the same manner as in Example 1.

The average withdrawal time was 44 seconds and the amount of dust was 80 mg. -Example 11-The same procedure as in Example 1 was performed except that an adapter processed into an end face shape with a concave portion 34 shown in FIG. The extraction operation was performed on 100 reaction tubes in the same manner as in Example 1.
The adapter is made of stainless steel, outer diameter 19mm, inner diameter 17m
m. The average extraction time is 18 seconds,
The amount of dust was 83 mg. -Example 12-A reaction for producing acrylic acid from propylene was performed according to the method described in Example 1 of JP-A-11-130722. The number of reaction tubes was 10,000. The pre-catalyst used was a cylindrical catalyst having an outer diameter of 6 mm and a height of 6 mm.

After the reaction was continued for 8000 hours, the reaction tube was cooled, and the following extraction operation was performed. (Withdrawal operation) Using the same suction device and suction tube as in Example 8, the tip of the suction tube was inserted 2500 mm from the upper opening of the reaction tube toward the lower portion of the reaction tube, and only the latter-stage catalyst was extracted. When the latter stage catalyst was taken out from the solid trap device installed between the suction device and the suction pipe,
Only 0.1 wt% of Raschig ring was mixed in the latter catalyst, and only the latter catalyst could be selectively recovered. Then, the tip of the suction tube was moved 3 times
Only the Raschig ring was extracted by inserting 200 mm. When the Raschig ring was taken out from the solid trap device, the pre-catalyst was only 0.2 wt% during the Raschig ring.
Was mixed.

As described above, according to the method of the present invention, only the second-stage catalyst can be extracted without extracting the first-stage catalyst, and further, the catalyst and the like packed in each reaction zone are almost completely selectively extracted. Therefore, it is easy to separate, recover, and reuse the catalyst and the like extracted from the reaction tube. -Example 13-An empty reaction tube of the multitubular reactor in Example 12 was filled with the pre-stage catalyst of Example 12 at a bed height of 2800 mm. Next, when the Raschig rings were filled, the actual layer height was 820 mm against the target packed layer height of 700 mm for Raschig rings.

Therefore, using the suction tube and the suction device of the eighth embodiment, the tip of the suction tube is moved 250 mm from the upper opening of the reaction tube.
It was inserted to the position of 0 mm, and the upper 120 mm of the filled Raschig ring was extracted, and the height of the packed layer of the Raschig ring was set to 700 mm. In contrast to this method, in the conventional method such as Comparative Example 1, it is necessary to extract even the pre-filled pre-catalyst and re-fill it, and it is understood that the working efficiency is very poor.

[0061]

According to the present invention, the following effects can be achieved in extracting solids from the reactor. (A) The extraction operation can be performed in a safe and sanitary working environment with less generation of dust. (B) The time required for the extraction operation is reduced. Also,
When extracting from the upper opening of the reaction tube, (c) it is possible to extract solid matter to an arbitrary position in the reaction tube.

(D) It is easy to separate, recover and reuse the extracted catalyst and the like. Therefore, the method of the present invention is a very useful method for extracting solids from a tubular reactor.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the inclination angle of the tip of a suction pipe and the speed of extracting solids.

FIG. 2 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a step of extracting solids from a reaction tube.

FIG. 4 is a perspective view showing a structural example of a suction nozzle.

FIG. 5 is a schematic cross-sectional view for explaining a method of adjusting the extraction amount.

FIG. 6 is a schematic cross-sectional view showing a method of extracting only a solid material in a specific layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Reactor 12, 14 Entrance / exit 20 Reaction tube 30 Suction tube 32 Piping 34 Depressed part 36 Convex part 40 Solid trap device 70 Exhaust pump 90 Solid

Claims (3)

[Claims] 1. A method for extracting solids filled in a reaction tube of a multitubular reactor, wherein a suction tube connected to an exhaust suction device is inserted from an end of the reaction tube (a). Sucking the solids in the reaction tube together with the airflow from the tip of the suction tube, and extracting the solids from the reaction tube
(b) a method for extracting solid matter from a multitubular reactor. 2. The method according to claim 1, further comprising, after the step (b), a step (c) of separating and recovering a solid extracted from the suction pipe from an air stream. Method of removing solids. 3. The method according to claim 1, wherein in the step (a), the suction tube is inserted from an upper end of the reaction tube.