JP2012236161A - Fixed-bed multitubular reactor and production method for the fixed-bed multitubular reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixed-bed multitubular reactor which adequately lowers temperature difference in the reactor by intending to improve installation efficiency, reduce cost and improve production efficiency, and to provide a production method for the fixed-bed multitubular reactor.SOLUTION: The fixed-bed multitubular reactor 1 includes a shell part 10 in which a heating medium is fluidized; segmental circle type baffles 20a, 20b, 20c which are arranged in the shell part 10 and can change the fluidity direction of the heating medium; and a plurality of reaction tubes 30 which are inserted in a plurality of penetration holes 23 formed along the thickness direction of the segmental circle type baffles 20a, 20b, 20c, respectively, wherein a blocking material 31, which is packed according to fluidization of the heating medium, is arranged in a clearance C between the reaction tube 30 and the inner peripheral surface of the penetration hole 23.

Description

  The present invention relates to a fixed bed multitubular reactor in which a gas phase catalytic oxidation reaction using a solid catalyst is performed, and a method for producing a fixed bed multitubular reactor.

  In the gas phase catalytic oxidation reaction using a solid catalyst, a fixed bed multitubular reactor is widely used. The fixed-bed multi-tubular reactor is provided with a cylindrical shell portion that accommodates a flowing heat medium, a large number of reaction tubes installed inside the shell portion, and a heat medium horizontally disposed inside the shell portion. A baffle plate that regulates the flow of the heat medium so as to move upward (axial direction) after moving in the (radial direction), and the heat medium that flows reaction heat generated by the exothermic reaction outside the reaction tube Is to be removed.

  By the way, when an exothermic reaction is performed using a fixed-bed multitubular reactor, a large temperature difference may occur inside the reactor due to a drift of a heat medium, a progress of a local reaction, or the like. If a large temperature difference occurs inside the reactor, there will be a large difference in the reaction amount for each reaction tube, the catalyst deterioration rate, etc. It becomes difficult to make a decision. In addition, if a local high temperature zone is generated, a runaway reaction may occur and the catalyst may be quickly deactivated and replaced, or the reaction tube may be damaged and repairs may be required, resulting in a reduction in equipment costs. To increase.

Thus, for example, Patent Documents 1 to 3 below propose a method for reducing the temperature difference inside the reactor.
Specifically, Patent Document 1 describes a configuration in which a rectifying rod group is provided in parallel with the reaction tube outside the reaction tube inside the shell portion.
In Patent Document 2, a plurality of holes larger than the reaction tube are formed in the baffle plate, the reaction tube is inserted into each of the holes, and a clearance between the outer peripheral portion of the reaction tube and the inner peripheral surface of the hole of the baffle plate is disclosed. Is described as a flow path for the heat medium.

JP 2005-296721 A JP-A-2-213696 JP 58-123094 A

However, in the configuration of Patent Document 1 described above, the number of reaction tubes installed in the reactor is reduced, and the space not involved in the reaction is increased. Therefore, it can be said that the internal space of the reactor is fully utilized. There wasn't. Therefore, there is a problem that the amount of reaction products is small with respect to the scale of the reactor, and the equipment efficiency is low.
Moreover, in the structure of patent document 2, since the hole larger than the diameter of a reaction tube was formed in a baffle plate, there existed a tendency for the number and thickness of a reaction tube to be restrict | limited. Further, when the clearance between the reaction tube and the baffle plate is utilized as a heat medium flow path, the flow rate of the heat medium flowing along the baffle plate (along the radial direction of the reactor) is reduced. As a result, there is a possibility that heating and heat removal capability will be reduced particularly by the heat medium on the outer peripheral side of the reactor, and an excessive temperature difference may occur between the outer peripheral side and the inner peripheral side of the reactor.

Therefore, as a method of closing the above-described clearance, for example, as shown in Patent Document 3, a tube plate inner surface of a tube plate having a required number of through holes and a pipe inserted into the through holes is provided. There is known a method in which the joint gap is closed by welding with or without a filler material.
However, in the method of Patent Document 3, especially when a large number of reaction tubes exist in a dense manner, it is impossible to weld them together later, so the reaction tubes are inserted while welding one by one. We have to go. Therefore, a great deal of labor is required to close the entire clearance. As a result, there is a problem that the manufacturing cost increases and the manufacturing efficiency decreases. Further, if the entire clearance is closed by welding, the reactor may be damaged due to the baffle plate and the thermal expansion of the reaction tube that are caused by raising the temperature of the reactor to the reaction conditions.

  Therefore, the present invention has been made in view of the above-mentioned circumstances, and is intended to improve the equipment efficiency, reduce the cost, and improve the production efficiency, and can fix the temperature difference in the reactor sufficiently small. The present invention provides a method for producing a bed multitubular reactor and a fixed bed multitubular reactor.

The fixed bed multitubular reactor of the present invention includes a shell part in which a heat medium flows, a baffle plate installed in the shell part and capable of changing a flow direction of the heat medium, and the baffle plate A fixed-bed multitubular reactor having a plurality of reaction tubes loosely inserted in a plurality of through-holes formed along the thickness direction, the inner peripheral surface of the reaction tube and the through-holes Is provided with a plugging material filled in accordance with the flow of the heat medium.
In the fixed bed multitubular reactor of the present invention, it is preferable that the plugging material is a processing substance mixed in the heat medium and is made of fine particles.
Further, in the fixed bed multitubular reactor according to the present invention, the plugging material is a processing substance mixed in the heat medium, and is capable of reacting with at least one of the baffle plate and the reaction tube. Preferably, the scale is deposited on the at least one surface.
In the fixed-bed multitubular reactor according to the present invention, it is preferable that at least one of the baffle plate and the reaction tube is subjected to an exposure treatment.
In the fixed bed multitubular reactor of the present invention, it is preferable that a plurality of the baffle plates are installed along the extending direction of the reaction tube.
Further, the fixed bed multitubular reactor of the present invention is suitably used when producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen.

The method for producing a fixed-bed multitubular reactor according to the present invention includes a shell part in which a heat medium flows, a baffle plate installed in the shell part and capable of changing a flow direction of the heat medium, And a plurality of reaction tubes inserted into a plurality of through-holes formed along the thickness direction of the baffle plate, respectively. A clogging treatment step is provided in which a clogging material is filled in accordance with the flow of the heat medium in the clearance between the hole and the inner peripheral surface.
In the method for producing a fixed bed multitubular reactor according to the present invention, in the clogging treatment step, the heat medium mixed with fine particles is caused to flow into the shell portion, whereby the fine particles are filled in the clearance. It is preferable to do.
In the method for producing a fixed-bed multitubular reactor according to the present invention, in the blockage treatment step, the heat medium mixed with a treatment substance capable of reacting with at least one of the baffle plate and the reaction tube is used. Preferably, the scale is deposited on the at least one surface by flowing in the shell portion.
Further, in the method for producing a fixed-bed multitubular reactor according to the present invention, prior to the clogging treatment step, there is an exposure treatment step in which at least one of the baffle plate and the reaction tube is subjected to an exposure treatment. Preferably it is.

  The fixed bed multitubular reactor of the present invention can sufficiently reduce the temperature difference in the reactor while improving the equipment efficiency, reducing the cost, and improving the production efficiency.

It is a longitudinal section showing a fixed bed multi-tubular reactor in an embodiment of the present invention. It is I'-I 'sectional drawing of FIG. It is sectional drawing equivalent to FIG. 1, Comprising: It is the figure which showed the installation position of the thermocouple used for the Example and the comparative example. It is a top view of a fixed bed multitubular reactor, Comprising: It is the figure which showed the installation position of the thermocouple used for the Example and the comparative example.

Next, the present embodiment will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a fixed-bed multitubular reactor (hereinafter referred to as a reactor) of this embodiment.
As shown in FIG. 1, the reactor 1 of the present embodiment includes a cylindrical shell portion 10 and a plurality of (for example, three) missing circular baffle plates (baffle plates) 20 a installed in the shell portion 10. 20b, 20c, and a plurality of reaction tubes 30 installed inside the shell portion 10.
In addition, the reactor 1 fixes the lower ends of all the reaction tubes 30 and the lower fixing plate 40 which becomes the floor portion of the shell portion 10, and fixes the upper ends of all the reaction tubes 30 and becomes the ceiling portion of the shell portion 10. Above the upper fixing plate 50, the raw material introduction portion 60 provided below the lower fixing plate 40, the reaction product discharge portion 70 provided above the upper fixing plate 50, and above the lower fixing plate 40. A heat medium introduction pipe 80 installed to introduce a heat medium into the shell portion 10, and a heat medium that is disposed below the upper fixing plate 50 and above the heat medium introduction pipe 80 and discharges the heat medium from the shell portion 10. And a discharge pipe 90.

  The shell portion 10 has a heat medium flowing therein. In the present embodiment, the shell portion 10 is installed in a state in which the axial direction coincides with the vertical direction. In addition, there is no limitation in particular as a heat medium which flows in the shell part 10, Usually, the salt melt (what is called nighter) containing potassium nitrate and sodium nitrite, or 3: 7 mixture (For example, Dow Chemical) of biphenyl and diphenyl ether. An organic heat medium such as Dowsome manufactured by the company can be used.

2 is a cross-sectional view taken along the line II ′ of FIG.
As shown in FIG. 2, the missing circular baffle plates 20 a, 20 b, and 20 c have a shape in which a part of a disk having a diameter smaller than the inner diameter of the shell portion 10 is cut off. For example, carbon steel, stainless steel, or the like is used. It is configured. The missing circular baffle plates 20a, 20b, and 20c in the present embodiment are missing as if a part of the circular plate was cut linearly. In the present specification, the straight end portions 21 of the cut-out baffle plates 20a, 20b, and 20c that are formed by cutting off a part of the disc in a straight line are referred to as “linear”. It is referred to as “end 21”.

  Further, the oval baffles 20a, 20b, and 20c are installed such that the thickness direction (axial direction) coincides with the vertical direction and the surface direction extends along the horizontal direction. Therefore, a clearance B is formed between the inner wall 10a of the shell portion 10 and the linear end portions 21 of the missing circular baffle plates 20a, 20b, and 20c.

  In the present embodiment, with respect to the upper notch baffle plate 20a and the lower notch baffle plate 20c, the clearance B is within the shell portion 10 and the heat medium introduction pipe 80 and the heat medium discharge pipe 90 side. The linear end portion 21 is disposed so as to be disposed on the opposite side of the line. On the other hand, with respect to the middle rounded baffle plate 20b, the linear end portion 21 is arranged so that the clearance B is disposed on the heat medium introduction pipe 80 and the heat medium discharge pipe 90 side inside the shell portion 10. Has been placed. In other words, the middle-stage missing circular baffle plate 20b is disposed in the opposite direction to the upper and lower missing circular baffle plates 20a, 20c. Further, the missing circular baffle plates 20 a, 20 b, and 20 c are arranged at equal intervals along the axial direction of the shell portion 10. Note that the oval baffles 20a, 20b, and 20c are fixed by a support ring or a support beam (not shown) attached to the shell portion 10.

  As described above, by arranging the missing circular baffle plates 20a, 20b, and 20c, the inside of the shell portion 10 has the first chamber 11 between the lower fixed plate 40 and the lower cutout baffle plate 20c, the lower stage. A second chamber 12 between the non-circular baffle plate 20c and the middle-circular baffle plate 20b, a third chamber 13 between the middle circular baffle plate 20b and the upper partial baffle plate 20a, and The upper chamber is divided into a fourth chamber 14 between the upper circular plate baffle plate 20a and the upper fixed plate 50.

The first chamber 11 and the second chamber 12 are in communication with each other mainly by a clearance B generated between the linear end portion 21 of the lower circular baffle plate 20 c and the inner wall 10 a of the shell portion 10. Has been.
Further, the second chamber 12 and the third chamber 13 are in communication with each other mainly by a clearance B generated between the linear end portion 21 of the middle notched baffle plate 20 b and the inner wall 10 a of the shell portion 10. Has been.
The third chamber 13 and the fourth chamber 14 are in communication with each other mainly by a clearance B generated between the linear end portion 21 of the upper circular baffle plate 20a and the inner wall 10a of the shell portion 10. Has been.
Therefore, most of the heat medium introduced into the shell portion 10 from the heat medium introduction pipe 80 meanders through the shell portion 10 through the first chamber 11, the second chamber 12, the third chamber 13, and the fourth chamber 14. However, it rises and is discharged from the heat medium discharge pipe 90.

  A plurality of through holes 23 for loosely inserting the reaction tubes 30 are formed in the cutout baffle plates 20a, 20b, and 20c at intervals along the surface direction. Note that the inner diameter of the through hole 23 is larger than the outer diameter of the reaction tube 30.

  Each reaction tube 30 has a cylindrical shape arranged in a state where the axial direction coincides with the vertical direction inside the shell portion 10, and is made of, for example, carbon steel, stainless steel, or the like. Specifically, each reaction tube 30 is loosely inserted into a through hole 23 that overlaps when viewed from the axial direction among the plurality of through holes 23 formed in each of the oval baffles 20a, 20b, and 20c. Upper and lower ends are respectively fixed to the upper fixing plate 50 and the lower fixing plate 40 described above. Therefore, a clearance C is formed between the reaction tube 30 and the inner peripheral surface of the through hole 23 of the oval baffle plates 20a, 20b, and 20c. Each reaction tube 30 has a lower end opening in the raw material introduction part 60, and an upper end opening in the reaction product discharge part 70.

In addition, the cross-sectional shape of the reaction tube 30 is not particularly limited, and may be an elliptical shape, a polygonal shape, or other shapes. Further, the number of reaction tubes 30 is not particularly limited and is appropriately selected according to the required amount of reaction products. About an upper limit, it changes also with the processing machines at the time of producing the reactor 1, and it is usually thousands to tens of thousands. Moreover, the pitch between each reaction tube 30 can take arbitrary distances in the range which can be manufactured.
Moreover, there is no restriction | limiting in particular in the internal diameter and length of the reaction tube 30, Usually, an internal diameter is 10-50 mm and length is the range of 300-10000 mm.

The reaction tube 30 is filled with a catalyst. The catalyst is not particularly limited as long as the catalyst allows the reaction to proceed as intended. For example, a solid catalyst such as esterification reaction, transesterification reaction, addition reaction, or hydration reaction can be used, but the temperature change of the reaction system due to reaction exotherm is large, and gas phase contact where heat removal by a heat medium is important An oxidation reaction catalyst is preferably used. The shape of the catalyst is not particularly limited, and examples thereof include a spherical shape, a cylindrical shape, a ring shape, and a star shape. The size of the catalyst is not particularly limited, but the activity tends to decrease when the catalyst diameter becomes excessively large, and the pressure loss in the reaction tube increases when the catalyst diameter becomes excessively small. For this reason, the catalyst diameter is usually in the range of 0.1 to 10 mm.
Further, the catalyst may be carrier-free or a supported catalyst in which a catalyst is supported on a carrier. Examples of the carrier include inert carriers such as silica, alumina, silica / alumina, and silicon carbide. Examples of the shape of the carrier include a spherical shape, a cylindrical shape, a ring shape, and a star shape.

Further, when the catalyst is filled in the reaction tube 30, the catalyst may be diluted with an inert filler such as silica, alumina, silica-alumina, silicon carbide, titania, magnesia, ceramic balls, and stainless steel. . Examples of the shape of the inert filler include a spherical granular shape, a cylindrical pellet shape, a ring shape, a star shape, and a saddle shape.
Further, the catalyst may be divided into a plurality of catalyst layers and filled in the reaction tube 30. In that case, an inert filler layer may be interposed between the catalyst layers.

When filling the catalyst into the reaction tube 30, the control target amount of the catalyst is measured for each reaction tube 30 or each filling time, and the measured catalyst is charged into the reaction tube from the upper end opening. Here, the management target amount may be volume or mass, but mass is preferable in terms of high accuracy. The management target amount can be obtained from the volume of the reaction tube 30 when the management target amount is volume, and from the volume of the reaction tube 30 and the catalyst packing density separately measured in advance when the management target amount is volume.
Further, when measuring the catalyst, the difference between the catalyst amount charged in the reaction tube 30 and the control target amount is preferably within ± 10% of the average value of the catalyst amount, and within ± 5%. Is more preferable. If the difference between the amount of catalyst filled in the reaction tube 30 and the management target amount is not within this range, the catalyst load on the reaction tube 30 may become uneven. Further, when the reaction tube 30 is filled before the metered catalyst is completely filled in the reaction tube 30, a filling error due to a catalyst bridge or the like in the reaction tube 30 can be considered. Needs to be refilled with catalyst.

Here, a closing material 31 is filled in the clearance C between the reaction tube 30 and the inner peripheral surface of the through hole 23 of the oval baffle plates 20a, 20b, and 20c. The closing material 31 is made of fine particles such as sand, stainless steel, carbon steel, and copper, and closes the clearance C between the reaction tube 30 and the through hole 23. In addition, as the material of the plugging material 31, the kind of the fine particle substance and the mixing method are particularly limited as long as the clearance C between the reaction tube 30 and the through hole 23 is plugged and the plugged state is maintained at the reaction temperature. Not limited.
In addition, the clearance C between the reaction tube 30 and the through hole 23 can be set to an arbitrary value within a range in which the reactor 1 can be assembled, but the mainstream is the flow of the nighter in the radial direction of the reactor 1. For the purpose, it is preferably set to 0.5 mm or less.

The plugging material 31 of this embodiment is filled in the clearance C described above by a process performed after the assembly of the reactor 1 (blocking process step). Specifically, the heat medium mixed with the above-described fine particles is introduced into the shell portion 10 from the heat medium introduction pipe 80. Then, the heat medium flows in the horizontal direction (plane direction) in the first chamber 11 along the lower surface of the missing circular baffle plate 20c, and the linear shape of the inner wall 10a of the shell portion 10 and the missing circular baffle plate 20c. It is introduced into the second chamber 12 through the clearance B between the end portion 21. The heat medium flows in the second chamber 12 along the direction opposite to the flow direction in the first chamber 11 along the upper surface of the oval baffle plate 20c.
After that, the flow direction of the heat medium is sequentially turned back by the oval baffles 20b, 20a, and the heat medium flows while meandering in the shell portion 10, thereby allowing the second chamber 12, the third chamber 13, and the fourth chamber 14 to pass through. Via, it is discharged from the heat medium discharge pipe 90.

In this case, most of the heat medium flowing in the shell portion 10 passes through the clearance B as described above, but some of the heat medium is part of the reaction tube 30 and the circular baffle plates 20a and 20b. , 20c passes through the clearance C between the inner peripheral surface of the through hole 23. Then, the fine particles mixed in the heat medium are filled in the clearance C, and finally the clearance C is closed by the fine particles.
As described above, the closing material 31 is formed in the clearance C, and the reactor 1 of the present embodiment is completed.

When the closing material 31 is filled in each clearance C, mixing of the fine particles into the heat medium is stopped, and only the heat medium is caused to flow. Then, the raw material is introduced from the raw material introduction unit 60 in a state where only the heat medium is allowed to flow outside the reaction tube 30 of the shell portion 10. The raw material introduced from the raw material introduction part 60 is introduced into the reaction tube 30 from the lower end opening of the reaction tube 30 and flows in the reaction tube 30 along the axial direction (vertical direction). The raw material reacts with the catalyst filled in the reaction tube 30 and then becomes a reaction product and is discharged from the reaction product discharge unit 70 through the upper end opening of the reaction tube 30. The reaction product discharged to the reaction product discharge unit 70 is supplied from the reactor 1 to the next step via the reaction product discharge unit 70.
In this case, heat is supplied to the reaction tube 30 by the heat medium or reaction heat generated in the reaction tube 30 is removed. In addition, you may introduce a raw material at the time of a closure process process.

The reactor 1 of this embodiment is preferably used for an oxidation reaction, a reduction reaction, a dehydration reaction, a neutralization reaction, and a substitution reaction, and particularly preferably used for an oxidation exothermic reaction. Therefore, in the following description, a specific example of methacrylic acid produced by vapor phase catalytic oxidation of methacrolein with molecular oxygen in the oxidation exothermic reaction will be described.
First, in the production of methacrylic acid using the reactor 1, a catalyst layer of a catalyst for producing methacrylic acid is previously formed in the reaction tube 30. The catalyst layer may be one layer or two or more layers.

As the catalyst for producing methacrylic acid constituting the catalyst layer, a composite oxide whose composition is represented by the following formula (1) is preferable.
Mo _a P _b Cu _c V _d X _e Y _f O _g (1)
In the formula (1), Mo, P, Cu, V and O are molybdenum, phosphorus, copper, vanadium and oxygen, respectively, X is iron, cobalt, nickel, zinc, magnesium, calcium, strontium, barium, At least one selected from the group consisting of titanium, chromium, tungsten, manganese, silver, boron, silicon, tin, lead, arsenic, antimony, bismuth, niobium, tantalum, zirconium, indium, sulfur, selenium, tellurium, lanthanum and cerium Y is at least one element selected from the group consisting of potassium, rubidium, cesium and thallium. a, b, c, d, e, f and g represent the atomic ratio of each element, and when a = 12, b = 0.5-3, c = 0.01-3, d = 0.01. ˜2, e = 0˜3, f = 0.01-3, and g is an atomic ratio of oxygen necessary to satisfy the valence of each element described above.
In addition to the methacrylic acid production catalyst, other additive components may be mixed in the catalyst layer. Examples of other additive components include the above-described inert filler carrier. The catalyst precursor may contain an organic substance such as water-soluble cellulose.

After the formation of the catalyst layer, the heat medium is introduced into the shell portion 10 from the heat medium introduction pipe 80, and the first chamber 11, the second chamber 12, and the second chamber 12, which are divided into steps by the oval baffles 20a, 20b, 20c, The third chamber 13 and the fourth chamber 14 are caused to flow and discharged from the heat medium discharge pipe 90.
At the same time, a raw material gas containing at least methacrolein and molecular oxygen is introduced into the reaction tube 30 through the raw material introduction unit 60, and methacrolein and molecular oxygen are reacted in the catalyst layer, thereby allowing methacrylic acid to react. Can be manufactured. The heat of reaction generated by the reaction is removed by a heat medium flowing outside the reaction tube 30.
The reaction product flowing out from the reaction tube 30 is sent to the next step from the reactor 1 via the reaction product discharge unit 70.

The concentration of methacrolein contained in the source gas can be appropriately selected, but is preferably 1 to 20% by volume, more preferably 3 to 10% by volume.
The raw material gas is preferable in that it is economical to mix air with methacrolein and to use molecular oxygen contained in the air. However, air mixed with pure oxygen may be mixed with methacrolein. . In this case, the amount of oxygen in the raw material gas is preferably 0.3 to 4 times mol and more preferably 0.4 to 2.5 times mol with respect to methacrolein.
The source gas is preferably diluted with an inert gas such as nitrogen or carbon dioxide.

The reaction pressure in the gas phase catalytic oxidation is preferably within the range of normal pressure (0 MPaG (gauge pressure)) to several atmospheric pressures (eg, 0.3 MPa).
The reaction temperature is preferably 230 to 450 ° C, more preferably 250 to 400 ° C.
The flow rate of the raw material gas is not particularly limited. Usually, a flow rate at which the contact time of the raw material gas with the catalyst for methacryl production is 1.5 to 15 seconds is preferable, and a flow rate at which the contact time is 2 to 5 seconds is more preferable. .

As described above, in this embodiment, the clearance C between the reaction tube 30 and the through holes 23 of the oval baffles 20a, 20b, and 20c is closed by the closing material 31 that is filled in accordance with the flow of the heat medium. It was set as the structure to do.
According to this configuration, the heat medium flows in the horizontal direction along the non-circular baffles 20a, 20b, and 20c and flows while meandering in the shell portion 10 from the first chamber 11 to the fourth chamber 14. Will do. Therefore, the flow state of the heat medium can be controlled, and the heat medium can be uniformly distributed over the entire area in the shell portion 10. Thereby, since the heat removal capability of the heat medium can be sufficiently utilized, local heat generation in the reactor 1 can be suppressed, and the temperature difference in the reactor 1 can be sufficiently reduced. In this case, local heat generation in the vicinity of the inner wall 10a of the shell portion 10 can be suppressed, and the temperature difference in the horizontal direction in the shell portion 10 can be sufficiently reduced.
Therefore, it is possible to suppress the occurrence of runaway reaction in the reactor 1, rapid deactivation of the catalyst, breakage of the reaction tube 30 due to thermal expansion of the reaction tube 30 and the circular baffle plates 20a, 20b, and 20c. Therefore, the equipment cost can be reduced.

  In this case, unlike Patent Document 1 described above, there is no need to provide a rectifying rod group that does not contribute to the reaction inside the shell portion 10, so that the internal space of the reactor 1 can be fully utilized. As described above, since the heat medium does not pass through the clearance C between the reaction tube 30 and the oval baffles 20a, 20b, and 20c, the number and thickness of the reaction tubes 30 are not limited. As a result, since the entire region of the reactor 1 can be efficiently utilized for the reaction, a reduction in facility efficiency can be suppressed and acquisition of the target product in a high yield can be achieved.

In particular, in the present embodiment, the total clearance C between the reaction tube 30 and the non-circular baffle plates 20a, 20b, and 20c can be easily achieved by flowing a heat medium mixed with fine particles into the reactor 1. Can be blocked at once. As a result, as in Patent Document 3 described above, the clearance C between the reaction tube 30 and the non-circular baffle plates 20a, 20b, and 20c can be reduced in cost compared to the case where the clearance C is closed one by one by welding or the like. And improvement of manufacturing efficiency can be aimed at.
In addition, according to the present embodiment, the heat medium can be more efficiently distributed over the entire region in the reactor 1 by arranging a plurality of the oval baffles 20a, 20b, and 20c along the vertical direction. Can do.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, the number of the oval baffles 20a, 20b, and 20c installed, the interval between the oval baffles 20a, 20b, and 20c can be appropriately changed. However, when the number of the missing circular baffle plates is an even number, the attachment position of the heat medium discharge pipe 90 in the shell portion 10 is a position of 180 ° with respect to the heat medium introduction pipe 80.
Furthermore, in the above-described embodiment, the shell portion and the baffle plate are formed in a circular shape in a plan view. However, the design is not limited thereto, and the design can be appropriately changed such as a rectangular shape in a plan view.

In the above-described embodiment, the case where the heat medium is made to flow from below to above has been described, but conversely, the heat medium may be made to flow from above to below. Further, the flow direction of the raw material gas in the reaction tube 30 may flow from the upper side to the lower side.
Further, the missing circular baffle plate may be missing such that a part of the disk is cut out in a curved manner, or may be missing so that a part of the disk is cut out in a wedge shape.

  In the above-described embodiment, the case where the clearance C is filled with the fine particles by flowing the heat medium mixed with the fine particles into the shell portion 10 in the closing process is described. However, the present invention is not limited to this. Any structure may be used as long as the closing material 31 is formed in the clearance C according to the flow. Such a configuration will be described below.

For example, first, a scale (blocking material) such as an oxide is formed on at least one (hereinafter referred to as a reaction member) by reacting with at least one of the reaction tube 30 and the oval baffles 20a, 20b, and 20c. The processing substance is mixed in the heat medium. Then, after assembling the reactor 1, the heat medium mixed with the processing substance is caused to flow in the shell portion 10 under the same conditions as described above. Thereby, a scale is formed on the surface of the reaction member by a reaction (oxidation reaction) between the processing substance mixed in the heat medium and the reaction member. Thereby, the clearance C can be closed.
Examples of the treatment substance include an aqueous solution containing sodium chloride and calcium chloride, and a gas such as water vapor, ammonia, and chlorine. However, if the clearance is closed by reacting with the reaction member and forming a scale on the reaction surface, and the closed state is maintained at the reaction temperature, the type of treatment substance and the treatment method are not particularly limited. .

  Prior to the clogging treatment step, the reaction member before the assembly of the reactor 1 is exposed to the surface with the treatment substance (exposure treatment step), and then the reactor 1 is prepared and the same method as described above. A scale may be formed on the surface of the reaction member by a method.

EXAMPLES Examples and comparative examples according to the present invention are shown below, but the present invention is not limited to these.
(Example)
In a fixed-bed multitubular reactor having 20,000 reactor tubes 30 with a diameter of 30 mm in the reactor 1 having a diameter of 6 m and a height of 6 m, all the reaction tubes 30 are chlorinated before the reactor is assembled. The surface was impregnated with an aqueous solution containing 35% by mass of sodium under atmospheric pressure at room temperature for 10 hours. The treated reaction tube 30 was stored at room temperature under atmospheric pressure for several days until the reactor 1 was assembled.
In this way, in the reactor 1 assembled using the reaction tube 30 subjected to the exposure treatment, a salt melt containing potassium nitrate and sodium nitrite at a temperature of 280 ° C. is flowed as a heat medium to be in a steady state. At that time, the temperature difference (hereinafter referred to as ΔT) between the heat medium inflow temperature and the measured temperature at each thermocouple installed in the reactor 1 was calculated (see Table 1). In addition, about the installation location of a thermocouple, a vertical direction is shown by the symbol AF of FIG. 3, and a horizontal direction is shown by the numbers (1)-(5) of FIG. At this time, the yield of methacrylic acid was 78.3%.

(Comparative example)
A reactor of the same type as that of the example was prepared without performing the clogging of the clearance C with sodium chloride.
Table 2 shows ΔT when the heat medium was caused to flow into the reactor 1 under the same conditions as in Example 1 to reach a steady state. At this time, the yield of methacrylic acid was 77.7%.

1 Reactor 10 Shell part 20a, 20b, 20c Missing circular baffle plate (baffle plate)
30 reaction tube 31 plugging material

Claims (10)

A shell part in which a heat medium flows;
A baffle plate installed inside the shell portion and capable of changing a flow direction of the heat medium;
A fixed-bed multitubular reactor having a plurality of reaction tubes loosely inserted into a plurality of through holes formed along the thickness direction of the baffle plate,
A fixed-bed multitubular reactor in which a clearance between the reaction tube and the inner peripheral surface of the through-hole is provided with a plugging material filled in accordance with the flow of the heat medium.   The fixed bed multitubular reactor according to claim 1, wherein the plugging material is a processing substance mixed in the heat medium and is made of fine particles.   The plugging material comprises a scale deposited on the surface of at least one of the processing substances mixed in the heat medium and capable of reacting with at least one of the baffle plate and the reaction tube. Item 3. The fixed-bed multitubular reactor according to Item 1.   The fixed-bed multitubular reactor according to claim 3, wherein at least one of the baffle plate and the reaction tube is subjected to an exposure treatment.   The fixed-bed multitubular reactor according to any one of claims 1 to 4, wherein a plurality of the baffle plates are installed along the extending direction of the reaction tube.   The fixed bed multitubular reactor according to any one of claims 1 to 5, which is used in producing methacrylic acid by vapor-phase catalytic oxidation of methacrolein with molecular oxygen. A shell part in which a heat medium flows;
A baffle plate installed inside the shell portion and capable of changing a flow direction of the heat medium;
A plurality of reaction tubes respectively inserted into a plurality of through holes formed along the thickness direction of the baffle plate, and a method for producing a fixed-bed multitubular reactor,
A method for producing a fixed-bed multitubular reactor having a closing process step of filling a closing material in accordance with the flow of the heat medium in a clearance between the reaction tube and the inner peripheral surface of the through-hole. .   The method for producing a fixed-bed multitubular reactor according to claim 7, wherein in the clogging treatment step, the clearance is filled with the fine particles by flowing the heat medium mixed with the fine particles into the shell portion.   In the clogging treatment step, the heat medium mixed with a treatment substance capable of reacting with at least one of the baffle plate and the reaction tube is caused to flow into the shell portion, whereby a scale is formed on the at least one surface. The method for producing a fixed-bed multitubular reactor according to claim 7, which is deposited.   The method for producing a fixed-bed multitubular reactor according to claim 9, further comprising an exposure process step of performing an exposure process on at least one of the baffle plate and the reaction tube prior to the blocking process step.

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