JP2001137689A - Gas phase catalytic oxidation reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the temperature distribution of a heating medium and to suppress the generation of a hot spot in a reactor. SOLUTION: A multi-tube reactor is provided with perforated disk type baffle plates and disk type baffle plates. In addition to them, the reactor is provided with reaction tubes as the perforated parts of the perforated disk type baffle plates and a spatial part in the center of the shell of the reactor where the reaction tube are not arranged. Axial stream power for moving the heating medium can be reduced by the arrangement like this and moreover heat is uniformly removed from each of the reaction tubes so that the hot spot is not increased. By using this reactor (meth)acrylic acid and/or (meth) acrolein can be manufactured by catalytically oxidizing a gas containing propylene or isobutylene in the gaseous phase with low energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multitubular reactor having a reaction tube which is not supported by a perforated disk-shaped baffle, and a method for producing (meth) acrylic acid or (meth) acrolein using the reactor. About.

[0002]

2. Description of the Related Art A catalytic gas-phase oxidation reaction using a multitubular reactor is a commonly used means for efficiently removing heat generated by the reaction. While using a multitubular reactor having a plurality of reaction tubes built in the reactor shell, a catalyst is filled in the reaction tubes and a reactant gas is supplied to perform a catalytic gas phase oxidation reaction.
By circulating a heat medium that absorbs the reaction heat inside the reaction tube shell,
The generated heat of reaction is removed.

However, in the catalytic gas-phase oxidation reaction using such a multitubular reactor, a hot spot is apt to be generated on the inlet side of the raw material, and the catalyst is deteriorated due to an excessive exothermic reaction and the selectivity of the target product is reduced. Reduction is a problem.

In order to solve such a problem, for example, Japanese Patent Publication No. 52-15272 discloses a multitubular reactor having a heat exchange medium circulating device, in which a baffle plate is arranged in a reactor shell. A disclosed reactor is disclosed. It is disclosed that the presence of the baffle keeps the speed of the lateral flow in an area almost constant, thereby also keeping the heat transfer in one area constant. Specifically, the reactor disclosed in the publication has an upright reaction tube arranged in an annular shape built in a reactor shell, and upper and lower ends of the reaction tube are hermetically attached to a tube plate. In the reaction tube, a plurality of horizontal perforated disk-shaped baffles and a disk-shaped baffle are alternately formed at the center and outer edges of the reaction tube at intervals in the lateral direction. At the center of the reactor shell, a tie rod and a spacer for mounting a disk-shaped baffle are provided.

Here, FIG. 1 schematically shows a conventional multi-tube type reaction tube incorporating a perforated disk-shaped baffle plate and a disk-shaped baffle plate. Disk type baffle 3
And a tie rod and a spacer 7 for connecting the two. A perforated disk-shaped baffle plate 2 is connected to this through another tie rod and a spacer, a reaction tube 4 is connected to a through hole provided in each baffle plate, and the reaction tube connected to this baffle plate is connected to a reactor. It is built in the shell 1. A heating medium 10 is introduced into the reactor shell 1 through an annular conduit 11a by an axial flow pump (not shown) or the like. The introduced heat medium 10 moves inside the reactor shell 1 while changing its direction by the perforated disc-shaped baffle 2 and the disc-shaped baffle 3. That is, the movement of the heat medium 10 is for removing heat from the reaction tube, and a baffle plate is required to secure a flow path for the heat medium 10, thereby uniformly removing heat from the reaction tube. In this case, all the reaction tubes 4 are always fully supported by the perforated disk-shaped baffle plate 2. In the case where the reaction tube 4 is not fully supported, that is, for example, the reaction tube 4 which is arranged in the hole of the perforated disk type baffle plate 2 and is not supported
This is because the heat medium 10 rises and falls from the central hole of the perforated disk-shaped baffle plate 2, so that uniform heat removal in such a reaction tube 4 becomes insufficient. However, the large lateral movement of the heat medium causes an increase in the pressure loss of the heat medium,
Excessive power energy is required.

On the other hand, the heating medium introduced into the reactor shell is:
After the heat of the reaction tube is removed, it is discharged out of the reactor shell, cooled by a heat exchanger or the like, and circulated and used in the reactor shell. For example, Japanese Patent Application Laid-Open No. 8-92147 discloses that a heat exchange agent is co-flowed in a method of catalytic gas-phase oxidation of propene to acrolein while maintaining a specific selectivity and conversion using a multitubular reactor. A catalytic gas-phase oxidation method is disclosed in which a baffle plate is disposed in a reaction vessel and a flow rate of a heat exchange agent is adjusted so that a temperature rise of a heat medium in a reactor becomes 2 to 10 ° C. According to the method described in this publication, acrolein is obtained by catalytic gas-phase oxidation of propene using a catalytically active composite metal oxide at a temperature heated in a multitubular reactor while reducing the hot spot temperature. Is disclosed.

However, the heat yield is calculated from the balance between the amount of heat generated by the reaction and the amount of heat consumed by cooling. In addition, the hot spot temperature is rate-determined at the portion having the highest amount of heat among many reaction tubes. Therefore, even if a heat medium is introduced into the reactor shell side to remove the heat of reaction, unless the removal of the heat of reaction is performed uniformly over the entire reaction tube, an excessive rise in the temperature of the reaction tube will occur, and a side reaction will occur. However, the risk of a decrease in yield, acceleration of catalyst deterioration, and runaway reaction cannot be ruled out. In this regard, Japanese Patent Application Laid-Open No. 8-92
As is clear from the example described in Japanese Patent No. 147,
Under the same heat generation conditions, the temperature rise of the heat medium is 1 ° C., regardless of whether the heat medium flows countercurrently or cocurrently in the reactor shell.
The pump power required to limit to Therefore, an efficient means for uniformly reducing the hot spot temperature of each reaction tube is required.

Further, a gas may be introduced into the reactor shell with the introduction of the heat medium into the reactor shell. Since the heating medium is subjected to a large temperature change such as heating accompanying the heat removal of the reaction tube and subsequent cooling, it is easy for the gas to be contained therein as it expands and contracts, and this gas accumulates in the reactor shell.
In general, when introducing the heat medium into the reactor shell at the start of use of the reactor, the gas vent is opened to facilitate the introduction of the heat medium. However, when the reactor is used, the gas is closed because it is used. Collects at the top of the reactor. Therefore, there is no heat medium in the gas reservoir, and the heat of the reaction tube cannot be sufficiently removed. Further, the reaction tube may be corroded by the gas.

As described above, in the conventional multitubular reactor, a baffle plate is disposed and heat is circulated at a specific flow rate in order to remove heat from the reaction tube. Is not enough. Further, in the case of industrially producing a target product using such a multitubular reactor, it is also an important subject to balance the yield of the target product with power consumption. In particular, if the amount of the circulating heat medium is increased in order to efficiently remove heat by the multitubular reactor, the power energy for circulating the heat medium eventually increases, which is disadvantageous. Further, if the heat transfer area is increased by reducing the size of the reaction tube, the number of reaction tubes is increased, and the reaction apparatus becomes expensive.

[0010] Accordingly, there is a need for the development of a reactor capable of uniformly removing heat, reducing the hot spot temperature and reducing motive energy while maintaining the selectivity of the target product.

[0011]

Means for Solving the Problems As a result of a detailed study of the movement of the heat medium in the reactor, the present inventor found that when a reaction tube was also arranged inside a perforated disk-type baffle plate, It has been found that the vessel can be miniaturized and the yield of the target product is not different from the conventional one, and the present invention has been completed.

That is, the above-mentioned problems are as described in the following (1) to (1).
0).

(1) A plurality of annular conduits for introducing or discharging a heat medium in a radial direction are disposed on the outer periphery, and a cylindrical reactor shell having a raw material supply port and a product discharge port; A circulator connected to each other, a plurality of reaction tubes holding the reactor by a plurality of tubesheets, and a perforated disk-type baffle plate for changing the direction of a heat medium introduced into the reactor shell And a disc-shaped baffle plate in the longitudinal direction of the reaction tube, wherein the reaction tube is held at a center interval of 1.2 to 1.4 times the outer diameter of the reaction tube, A reactor for catalytic gas phase oxidation reaction, comprising a space in the center of a reactor shell where no reaction tubes are arranged, and a reaction tube not supported by a perforated disk-shaped baffle plate.

(2) The reactor according to the above (1), further comprising a reaction tube that is not supported by the disc-shaped baffle.

(3) The sectional area of the space is 0.5 to 5% of the sectional area of the reactor shell, the sectional area of the disc-shaped baffle is 50 to 95% of the sectional area of the reactor, and The reactor according to the above (1) or (2), wherein the cross-sectional area of the hole of the perforated disk-shaped baffle plate is 2 to 25% of the cross-sectional area of the reactor.

(4) The above-mentioned (1) to (1), further comprising a heat medium inlet after cooling in the heat medium circulation port of the annular conduit or the circulation device discharged from the reactor shell.
The reactor according to (3).

(5) Further, a gas discharge conduit for discharging the gas introduced and stored in the reactor shell together with the heat medium to the outside of the reactor shell is provided, wherein (1) to (5). The reactor according to any one of 4).

(6) Further, the annular conduit has a plurality of rows of openings through which the heat medium passes, and the width of the openings is 5 to 5 of the center interval.
The reactor according to any one of the above (1) to (5), wherein the value of 0% and the value of opening length / opening width are in the range of 0.2 to 20.

(7) At least one of the aperture rows is 2
The reactor according to the above (6), having the above opening.

(8) At least one shielding plate for partitioning the inside of the reactor shell into at least two closed spaces in the longitudinal direction of the reaction tube. 1
A reactor according to item 6.

(9) The reactor according to any one of the above (1) to (8), which is used for producing (meth) acrylic acid or (meth) acrolein.

(10) (meth) acrylic acid and / or (meth) acrylic acid using the reactor according to any one of the above (1) to (9)
Or a method for producing (meth) acrolein.

[0023]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylindrical reactor shell having a plurality of annular conduits for introducing or discharging a heating medium in a radial direction and having a raw material supply port and a product discharge port disposed on an outer periphery thereof; A circulator for connecting a plurality of annular conduits to each other, a plurality of reaction tubes bound to the reactor by a plurality of tubesheets, and a perforation for changing a direction of a heating medium introduced into the reactor shell; In a multitubular reactor having a disk-shaped baffle plate and a disk-shaped baffle plate in the longitudinal direction of the reaction tube, the reaction tube has a center distance of 1.2 to 1.4 times the outer diameter of the reaction tube. A reactor for catalytic gas phase oxidation reaction, characterized by having a space in which no reaction tubes are arranged in the center of the reactor shell and having a reaction tube not supported by a perforated disk-shaped baffle plate is there.

Conventionally, the baffle plate secures the flow path of the heat medium, and unless all the reaction tubes are fully supported by the baffle plate, for example, the baffle plate exists in the hole of the perforated baffle plate. The reaction tubes that are not supported by the reaction tube do not come into contact with the heat medium flow flowing in the plane direction of the baffle plate, and sufficient heat exchange is not performed only by the up-and-down flow generated from the outer periphery of the hole, reducing the thermal efficiency. The tube was fully supported by the disk portion of the perforated disk-shaped baffle. However, when the reaction tube was also arranged inside the perforated disk-shaped baffle plate, it was unexpected that the reaction product was caught at a center interval within a specific range of the outside diameter of the reaction tube. The yield and the selectivity of the target product could be maintained, and the kinetic energy for flowing the heat medium was reduced. By such an effect, the cross-sectional area of the reactor with respect to the storage reaction tube could be reduced. . Hereinafter, embodiments of the present invention will be described with reference to FIG.

The present invention is directed to a cylindrical reactor shell 1 having a plurality of annular conduits 11a and 11b for introducing or discharging a heat medium in a radial direction and having a raw material supply port 50 and a product discharge port 51 arranged on the outer periphery. Raw material supply port 5 of the reactor shell 1
Tube sheets 6a and 6b for partitioning the gas discharge port 51 from the product discharge port 51
A plurality of reaction tubes 4 and a perforated disk-shaped baffle plate 2 and a disk-shaped baffle plate 3 for changing the direction of the heat medium introduced into the reactor shell 1 Is a multitubular reactor having a longitudinal direction.

The perforated disc-shaped baffle 2 and the disc-shaped baffle 3
Are alternately arranged in the longitudinal direction of the reaction tube 4, but the distance between the perforated disc-shaped baffle 2 and the disc-shaped baffle 3 is not particularly limited. Therefore, when the hot spot in the reaction tube varies depending on the catalytic gas phase oxidation reaction to be reacted, it can be appropriately selected according to the position of the hot spot, a change in the temperature of the hot spot, and the like.

On the other hand, the reaction tube 4 has an outer diameter of 1.
It is necessary to arrange at a center interval of 2 to 1.4 times, more preferably 1.25 to 1.35 times, and particularly preferably 1.25 to 1.30 times. 1.2 of the outer diameter of the reaction tube
If the ratio is less than twice, the interval between the reaction tubes becomes narrower, which is useful for downsizing the reactor, but the heat removal efficiency in the reaction tube near the center is reduced, so that it becomes difficult to reduce the hot spot temperature. is there. On the other hand, if it exceeds 1.4 times, the reactor becomes large, the linear velocity in the shell decreases, and the heat medium drifts, so that the heat removal efficiency decreases. However, there is no particular limitation on the inner and outer diameters of the built-in reaction tube itself and the length of the reaction tube. Therefore, the size of the reaction tube used for the known catalytic oxidation reaction can be selected. In the present invention, the reaction tube preferably has an inner diameter of 15 to 50 mm, more preferably 20 to 40 mm, particularly preferably 2 to 50 mm from the viewpoint of heat removal efficiency.
0 to 30 mm.

Further, the present invention is characterized in that it has a space at the center of the reactor shell and a reaction tube 4a which is not supported by the perforated disk-shaped baffle plate 2. conventionally,
A tie rod and a spacer may be provided at the center of the reactor shell, and a perforated disk-shaped baffle 2
Supported all the reaction tubes 4 by
The reaction tube 4 shown in FIG.
By arranging at least one row of a, it is possible to increase the number of reaction tubes accommodated in the same reactor shell diameter, and at the same time, to reduce the power energy of the heating medium and to secure a heat removal efficiency that is not different from the conventional one. I was able to do it. Although the details of this reason are unknown, the pressure loss of the heating medium is reduced by the space in the center and the disposition of the reaction tube which is not supported by the perforated disk-shaped baffle plate 2, which leads to a reduction in power energy. It is considered that the heat exchange rate was improved due to the improvement in the linear velocity, and the reduction of the hot spot temperature and the selectivity, which are not different from those in the related art, were possible.

The sectional area of the space is preferably 0.5 to 5%, more preferably 1 to 4%, particularly preferably 1 to 2% with respect to the sectional area of the reactor shell. 0.
If it is less than 5%, the flow of the heat medium around the center is poor, the heat removal of the reaction tube becomes insufficient, and the hot spot temperature cannot be reduced. On the other hand, if it exceeds 5%, the diameter of the reactor shell increases, and the thermal efficiency decreases due to a decrease in the linear velocity. Instead of a tie rod at the center of the reactor shell 1 or the like, a perforated disc-shaped baffle 2 or a disc-shaped baffle 3 is used.
A plurality of tie rods and spacers may be provided so as to penetrate the perforated disk-shaped baffle plate 2.

The cross-sectional area of the disc-shaped baffle 3 is preferably 50 to 95%, more preferably 60 to 90%, particularly preferably 70 to 90% of the cross-sectional area in the reactor shell 1. 85%. If it is less than 50%, the heat medium flow near the reactor shell wall surface is poor and the heat efficiency is reduced. If it exceeds 95%, the power energy is increased and the flow of the heat medium near the disk-type baffle plate is deteriorated and the heat efficiency is reduced. Because you do.

The hole cross-sectional area of the perforated disk-shaped baffle plate 2 is preferably 2 to 25% of the cross-sectional area in the reactor shell, more preferably 4 to 20%, and particularly preferably 4 to 20%. Preferably it is 6 to 18%. If it is less than 2%, the pressure loss of the heating medium increases, and if it exceeds 25%, uniform heat removal becomes difficult.

The present invention has a reaction tube 4a which is not supported by the perforated disk-shaped baffle plate 2, but has a reaction tube 4b which is not supported by the disk-shaped baffle plate as shown in FIG. It may be. By disposing such reaction tubes 4b, the number of reaction tubes disposed in the reactor shell 1 can be increased. In addition, a specific proportion of the central space,
With the selection of the hole area of the perforated disk-shaped baffle and the area of the disk-shaped baffle, it has become possible to reduce the hot spot temperature and secure the yield of the target product.

It is preferable that these baffles are arranged so as not to overlap the position of the hot spot, more preferably 100 mm or more, particularly preferably 200 m or more.
m or more. This is because if the hot spot position of the reaction tube and the baffle plate support portion overlap, the efficiency of heat removal by the heat medium is reduced, and it is difficult to reduce the hot spot temperature. Such a hot spot position can be known by supplying a raw material gas or the like to a reaction tube filled with a catalyst in advance and measuring the temperature of each part of the reaction tube. When the hot spot position changes as the reaction progresses, a baffle plate may be provided in consideration of the changed area.

In the reactor according to the present invention, all or a part of the heat medium 10 is discharged out of the reactor shell 1 from a heat medium discharge port provided in the annular conduit 11a or 11b, and is connected to the annular conduits 11a and 11b. Is circulated from the other annular conduit 11b or 11a into the reactor shell 1 via a circulation device provided between them. If you have such a circulation device,
The heat medium 10 of the reaction apparatus in the case where the heat medium 10 whose flow path is secured by the perforated disk-shaped baffle plate 2 and the disk-shaped baffle plate 3 is introduced in an upward flow from the lower part of the reactor toward the upper part. Will be described with reference to FIG.

First, the heat medium 10 introduced from the annular conduit 11a and discharged from the annular conduit 11b is not taken out of the reactor shell 1 and the circulation device 30 but immediately goes to the heat medium discharge port 34 of the circulation device 30. Heat medium (this is heat medium 10
a) is introduced into the circulation device 30 from the heat medium circulation port 31 provided in the annular conduit 11b, is introduced into the annular conduit 11a through the heat medium discharge port 34, and is circulated in the reactor shell 1.

On the other hand, a part of the heat medium 10 is
The heat medium is taken out of the reactor shell 1 from the heat medium take-out port 12 provided in the reactor, cooled by a heat exchanger (not shown), and supplied from a heat medium inlet port 32 provided to face the heat medium circulating port 31 of the circulation device 30. be introduced. The discharge of the heat medium 10 to the outside of the reactor shell is not limited to the passage through the annular conduit 11b. For example, as shown in FIG. 4, after the heat medium 10 enters the circulation device 30 through the heat medium circulation port 31 from the annular conduit 11b. After being taken out of the reactor shell 1 from the heat medium outlet 12 provided at the upper part of the circulation device 30 and cooled by a heat exchanger (not shown), it is introduced from the heat medium inlet 32 provided in the annular conduit 11b. May be. In this way, when the heat medium 10b is taken out of the reactor shell and cooled, and the cooled heat medium 10b is circulated around the annular conduit 11b or the heat medium circulation port 31 of the circulation device 30 after cooling,
Since the supply portions of the heat medium 10a and the heat medium 10b in the circulation device 30 are adjacent to each other, the mixing of the both becomes easy. Further, the heat medium taken out from the heat medium outlet 12 shown in FIG. 4 can be circulated in the reactor shell via, for example, the annular conduit 11b. In this case, it is necessary to take a sufficient residence time for mixing in the annular conduit 11b. In the annular conduit 11b, a heat medium inlet 32 'is provided at a position facing the heat medium circulation port 31. Is preferred. Annular conduit 11
medium inlet 3 for introducing cooling medium 10b into cooling medium b
2 as 32 'is shown in FIG. In this case, FIG.
Does not exist. As described above, in the reactor of the present invention, the heat medium introduction port 32 for introducing the cooled heat medium 10b into the reactor shell 1 or the circulation device 30 is changed to the annular conduit 11b or the heat medium circulation port of the circulation device 30. It is preferable to have it near 31. Heat medium outlet 3 of circulation device 30
When the cooled heat medium 10b is circulated in the vicinity of 4, the heat medium 1b
Inadequate mixing of Oa and 10b resulted in reactor shell 1
The temperature distribution of the heat medium 10 circulated in the inside was uneven, and a local abnormal high temperature of the reaction tube 4 was easily generated. According to the present invention, the heat medium circulation port 31 is provided in the circulation device 30 as described above.
The heat medium 10a and the heat medium 10b are mixed very efficiently by supplying the heat medium (heat medium 10b) after cooling to the heat exchanger or by providing the heat medium inlet 32 in a part of the annular conduit 11b. . Moreover, the amount of heat absorbed during the movement in the circulation device 30 is extremely small, and the heat of reaction can be sufficiently removed as a heat medium. In addition, by using the heat medium 10 having a uniform temperature distribution, an abnormally high temperature of the hot spot can be uniformly prevented, and the amount of the circulating heat medium can be reduced.

The heat medium 10b after cooling in the present invention
When the heat medium introduction port 32 for introducing the heat medium is provided in the circulation device 30, a position opposed to the heat medium circulation port 31 can be exemplified as shown in FIG. 3, but as shown in FIG. When the heat medium outlet 12 is provided above the circulation device 30, the heat medium 1 is moved from a position facing the heat medium circulation port 31.
When 0b is introduced, a part of the cooled heat medium 10b flows out of the reactor through the heat medium outlet 12, which is disadvantageous in terms of thermal efficiency. In such a case, a heat medium discharge port which is located closest to the heat medium circulation port 31 in the circulation device 30 and is an outlet of the heat medium for discharging the heat medium from the circulation device to the reactor shell. 34 and the farthest position. When a plurality of heat medium circulation ports 31 are provided in the circulation device, the heat medium 10b may be introduced in any vicinity thereof. This is because in any case, the mixing of the heat medium 10b and the heat medium 10a is efficiently performed.

In the present invention, a heat medium inlet 32 may be provided in a part of the annular conduit on the outlet side of the reactor connected to the heat medium circulation port of the circulation device. In this way, the heat mediums 10a and 10b are already mixed when introduced into the circulation device 30, and the heat medium 10 having a uniform heat distribution in the circulation device 30 is obtained.
Is easy to prepare. In such a case, the heat medium inlet 3
The position 2 is preferably a position facing the circulation device 30 so that a sufficient residence time after mixing in the annular conduit can be secured.

When the heat medium is circulated in the upflow as shown in FIG. 4, the heat medium can be taken out from the heat medium outlet 12 provided in the upper part of the circulation device 30 by using the pump 33. In this case, it is preferable to provide the partition plate 37 so as not to mix with the heating medium 10b introduced from the heating medium introduction port 32 provided below.

The reactor of the present invention may have a stirring blade instead of the pump 33 or a stirring blade for efficiently mixing the heat medium 10a and the heat medium 10b in the circulation device 30. You may. This is because a heat medium having a uniform heat distribution can be obtained more efficiently. The heat medium 10 (heat medium 10a + heat medium 10b) having a uniform heat distribution in this way passes through the heat medium discharge port 34 of the circulation device 30 and then returns to the annular conduit 11 again.
a into the reactor shell 1. In the figure, the heat medium 1
0 (10a + 10b), the flow of the heat medium 10a, and the flow of the heat medium 10b are shown by adding respective symbols to the arrows indicating the flow paths.

In the present invention, the heat medium 10b taken out of the reactor shell 1 is preferably subjected to gas-liquid separation before or after the heat exchange. Heat medium 10 containing air bubbles
When b is used, gas is easily generated in the upper tube plate portion in the reactor shell, and uniform mixing of the heat medium 10a and the heat medium 10b can be easily performed by using the heat medium after degassing. This is because the distribution can be made uniform. As such a gas-liquid separation method, a method of preventing entrainment of gas by reducing the speed or securing the liquid height is typical, and other methods may be used.

The reactor of the present invention comprises an annular conduit 11a, 11
b. The heating medium is uniformly supplied or discharged from the entire circumferential direction of the reactor through the annular conduits 11a and 11b having openings intermittently communicated over the entire circumference, so that the heating medium is uniformly supplied and the hot spot is formed. This is because the temperature can be efficiently reduced. In this case, it is preferable that the annular conduit has a plurality of opening rows through which the heat medium passes. This will be described with reference to FIG. 5. For example, the annular conduit 11a has a plurality of opening rows A1, A2, etc., and the center distance A, which is the center distance between the openings of the nearest opening row in each opening row.
May be the same or different for each row,
0 mm, more preferably 100 to 400 mm, particularly preferably 200 to 300 mm. The center interval A is 50
mm, it is difficult to manufacture, while 500m
This is because if it exceeds m, it is difficult to uniformly feed the heat medium outside the reaction tube. Further, the numerical aperture in each aperture row is at least one or more. In FIG. 5, row A1 shows one numerical aperture, row A2 shows two numerical apertures, and row An shows four numerical apertures. Since the number of apertures present in each aperture row is different as described above, the interval between adjacent apertures does not have to be equal to the center interval A as shown in FIG. Also, the opening width B
Is 5 to 5 of the average center interval which is the average value of the center interval A.
It is 50%, more preferably 10 to 40%, particularly preferably 20 to 30%. If the opening width is less than 5%, the height of the annular conduit becomes high and large, while if it exceeds 50%, the opening height is low and it becomes difficult to feed the heat medium over a wide area of the pipe. Further, the value of the opening length C / the opening width B is preferably in the range of 0.2 to 20. Note that the center interval A
Does not need to be the same in all of the annular conduits, and similarly, the opening width B need not be the same in all of the annular conduits. By providing a plurality of openings, a more uniform heat medium 1
This is because the discharge and inflow of 0 becomes possible. For this reason, when calculating the opening width B in the present invention, the opening width B is calculated using the average center interval. The shape of the opening is not particularly limited, and examples thereof include a circle, an ellipse, an ellipse, and a rectangle.

In the embodiments shown in FIGS. 3 and 4, the heating medium 10 is supplied in the upflow regardless of whether the raw material is supplied in the upflow or the downflow.
In performing the catalytic gas phase oxidation reaction in the reactor of the present invention, the raw material gas introduced into the reaction tube 4 can be used regardless of whether it is up-flow or down-flow. Heat medium 1
In addition, 0 can be introduced without particular limitation in the case of cocurrent or countercurrent to the raw material supply.

Further, the reactor of the present invention comprises a reactor shell 1
It is preferable that a gas outlet for discharging gas accumulated in the upper part of the reactor is closely attached to a tube plate in the reactor shell and piping is performed. Generally, gas is introduced into the reactor shell 1 when the heat medium 10 is introduced, and a space in which the heat medium does not exist is likely to be formed on the upper part of the reactor shell 1. Not enough heat can be removed locally,
Abnormal temperature rise easily occurs. Therefore, by providing the gas discharge port, the gas can be removed and filled with a heating medium to prevent local abnormal temperature rise of the reaction tube, thereby stabilizing the reaction conditions.

Next, a case where the heat medium is introduced in a downflow manner in the reactor of the present invention will be described with reference to FIG. Also in FIG. 6, a reaction tube 4a which is not supported by the perforated disk-shaped baffle plate 2 is disposed at the center of the reactor shell. The cooled heat medium 10 b is introduced into the circulation device 30 from the heat medium inlet 32. In this case, the annular conduit 11a
The heat medium discharged from the heat medium outlet 12 provided in the nozzle 1 is pushed up to a heat medium discharge pot 13 disposed above the upper tube plate 6b of the reactor shell 1 and then the nozzle 1
From 4 is discharged out of the system. In this case, the heat medium discharge pot 1
The same amount of the cooling medium as the heating medium 10 b discharged out of the system by 3 is supplied from the heating medium inlet 32. This makes it possible to ensure that the heating medium 10 in the reactor shell 1 is full. The heat medium 10b taken out of the reactor shell and cooled and circulated for use, and the heat medium 10a introduced from the heat medium circulation port 31 into the circulation device 30 (not circulated out of the reactor shell and immediately used The heat medium is mixed with a pump 33 such as an axial flow pump or a vortex pump, is pumped upward, and can be introduced from the heat medium discharge port 34 into the reactor shell 1 through the annular conduit 11b.
The amount of the heat medium introduced may be adjusted within the range of the circulating heat medium.

In any of the embodiments of the reactor of the present invention, the supply of the heat medium to the reaction shell 1 and the discharge from the shell are arranged on the upper and lower outer peripheral portions of the reactor, respectively. This can be done via annular conduits 11a, 11b. In this case, the heat medium 10 is discharged and received by the annular conduit 11a,
11b may be performed at a plurality of locations, and two or more circulation devices may be provided for this purpose. Although it is difficult to adjust a heat medium having a uniform temperature distribution by simply increasing the number of pumps, according to the present invention, since a heat medium having a uniform temperature distribution is supplied in the circulation device, a plurality of heat mediums are supplied. By arranging the circulation device,
This is because more efficient heat removal can be achieved.

Further, in the reactor of the present invention, means for applying back pressure are provided before and after the heat medium outlet of the heat medium 10b to apply a sufficient back pressure to the heat medium 10 flowing down the reaction tube. , A liquid full state can be ensured. Heating medium 10b is supplied to reactor shell 1
When extracting to the outside, heat medium 1 inside reactor shell 1
Although it is preferable to be able to secure a liquid full state by 0, it is possible to secure sufficient liquid back pressure by arranging the means with back pressure to apply sufficient back pressure to the heat medium flowing down the reaction tube. It is. Examples of such back pressure means include a resistance orifice, a valve, and a heat exchanger. Therefore, such a back pressure applying means can be further arranged in the reactor of the present invention.

Also, in the embodiment shown in FIG. 6, when the gas introduced along with the supply of the heating medium into the upper portion of the reactor shell 1 accumulates inside the reactor shell side, the reactor shell 1 may be used.
Of the heat medium discharge pot 13 and the space above the heat medium circulating device 30 through a pipe 15 inserted from the upper part of the reactor to the outer periphery of the reactor and a pipe 16 inserted to the center. This is because such a gas extraction conduit can prevent generation of gas accumulation in the reactor shell 1 which causes uneven heat removal in the reactor and causes an abnormal reaction. For example, as shown in FIG. 6, a gas discharge conduit 16 disposed above the reactor shell 1 is communicated with a gaseous phase portion of a heat medium discharge pot 13 located above the reactor upper tube plate surface to discharge gas. The gas can be discharged from the outlet 17 or the gas discharge conduit 15 in the reactor shell 1 can be discharged to a space above the circulation device 30 having a gas discharge nozzle 36.

FIG. 7 shows an example of the arrangement of the gas discharge conduit. For the gas accumulated on the outer periphery of the reactor, for example, a flow path is formed in the upper tube sheet 6b like the gas discharge conduit 15. The gas accumulated in the center of the reactor shell 1 may be connected to the outside of the reactor shell 1 through the upper tube sheet 6b.
The gas discharge conduit 16 may be provided directly below the gas outlet.

Hereinafter, a method for producing (meth) acrylic acid or (meth) acrolein by a catalytic gas phase oxidation reaction of a propylene or isobutylene-containing gas in the reactor of the present invention will be described with reference to FIG.

The catalytic gas phase oxidation reaction of the present invention is carried out by supplying a raw material gas to the catalyst 5 filled in the reaction tube 4.
The reaction gas is supplied into the reaction tube 4 filled with the catalyst 5 in the reactor shell 1, oxidized in the reaction tube to become a reaction product, and then discharged from the product gas discharge port 51.

In the present invention, in order to produce acrylic acid by a two-stage catalytic gas-phase oxidation reaction of a propylene-containing gas, for example, as a first-stage catalyst, a gaseous oxidation reaction of a propylene-containing raw material gas to produce acrolein is used. Commonly used oxidation catalysts can be used. Similarly, the latter catalyst is not particularly limited, and is generally used for producing acrylic acid by vapor-phase oxidation of a reaction gas containing mainly acrolein obtained in the former by a two-stage catalytic gas phase oxidation method. A catalyst can be used.

[0053] As the pre-catalyst has the general formula Mo _a -Bi _b -
_{Fe c -A d -B e -C f} -D g -O x (Mo, Bi, Fe represent molybdenum, represents bismuth and iron, A represents a least one element selected from the group consisting of nickel and cobalt, B Represents at least one element selected from alkali metals and thallium, C represents at least one element selected from the group consisting of phosphorus, niobium, manganese, cerium, tellurium, tungsten, antimony and lead, and D represents At least one element selected from the group consisting of silicon, aluminum, zirconium and titanium, O represents oxygen, and a, b, c, d, e, f, g and x represent Mo, Bi, Fe, It represents the atomic ratio of A, B, C, D and O, and when a = 12, b = 0.
1-10, c = 0.1-10, d = 2-20, e = 0.
001-5, f = 0-5, g = 0-30, and x is a value determined by the oxidation state of each element).

Further, as the latter catalyst, the general formula Mo _{a-
V b -W c -Cu d -A e} -B f -C g -O x (Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper,
A is antimony, bismuth, tin, niobium, cobalt,
Iron, represents at least one element selected from nickel and chromium, B represents at least one element selected from alkali metals, alkaline earth metals and thallium,
C represents at least one element selected from silicon, aluminum, zirconium and cerium, O represents oxygen, and a, b, c, d, e, f, g and x are Mo, V, W, respectively. , Cu, A, B, C, and O, and when a = 12, b = 2 to 14, c = 0 to
12, d = 0.1 to 5, e = 0 to 5, f = 0 to 5, g =
0 to 20 and x is a value determined by the oxidation state of each element).

In the present invention, isobutylene, t-butanol,
As a catalyst used when methacrylic acid is obtained by a two-stage catalytic gas-phase oxidation reaction of methyl-t-butyl ether, for example, as a pre-stage catalyst, a raw material gas containing isobutylene or the like is subjected to a gas-phase oxidation reaction to produce methacrolein. Commonly used oxidation catalysts can be used. Similarly,
There is also no particular limitation on the latter catalyst, and an oxidation catalyst generally used for producing methacrylic acid by subjecting a reaction gas mainly containing methacrolein obtained in the former stage by a two-stage catalytic gas phase oxidation method to gas phase oxidation is used. Can be used.

Specifically, as the pre-stage catalyst, the general formula Mo
_{a -W b -Bi c -Fe d -A} e -B f -C g -D h -O x is preferably one represented by (Mo, W, Bi represent molybdenum, represents a tungsten and bismuth, Fe is A represents iron, A represents nickel and / or cobalt,
B represents at least one element selected from alkali metals, alkaline earth metals and thallium, and C represents at least one element selected from the group consisting of phosphorus, tellurium, antimony, tin, cerium, lead, niobium, manganese and zinc. Represents a kind of element, D represents at least one kind of element selected from the group consisting of silicon, aluminum, titanium and zirconium, and O represents oxygen. A, b,
c, d, e, f, g, h and x are Mo,
Represents the number of atoms of W, Bi, Fe, A, B, C, D, and O. When a = 12, b = 0 to 10, c = 0.1 to
10, d = 0.1-20, e = 2-20, f = 0.00
1 to 10, g = 0 to 4, h = 0 to 30, and x are numerical values determined by the oxidation state of each element. Further, if the latter catalyst is one or more oxide catalysts containing molybdenum and phosphorus as main components,
Although not particularly limited, for example, phosphomolybdic acid-based heteropolyacid or a metal salt thereof is preferable, and a compound represented by the general formula M
_{o a -P b -A c -B d} -C e -D f -O x are preferably those represented by. (Wherein Mo represents molybdenum, P represents phosphorus, A represents at least one element selected from the group consisting of arsenic, antimony, germanium, bismuth, zirconium and selenium, B represents copper, Iron, chromium, nickel, manganese, cobalt, tin, silver, zinc,
C represents at least one element selected from the group consisting of palladium, rhodium and tellurium; C represents at least one element selected from the group consisting of vanadium, tungsten and niobium; ,
O represents at least one element selected from the group consisting of alkaline earth metals and thallium, and O represents oxygen.
A, b, c, d, e, f and x are each M
represents the atomic ratio of o, P, A, B, C, D and O, and a =
When fixed at 12, b = 0.5-4, c = 0-5, d =
0 to 3, e = 0 to 4, f = 0.01 to 4, and x are numerical values determined by the oxidation state of each element. The shape of the catalyst is also not particularly limited, and may be spherical, cylindrical,
The catalyst can be formed into a cylindrical shape or the like, and the molding method can be a carrier molding, an extrusion molding, a tableting molding, or the like, and a form in which these catalyst substances are carried on a refractory carrier is also useful.

The conditions for the gas phase catalytic oxidation reaction of propylene or isobutylene with molecular oxygen can be carried out by a conventionally known method. For example, taking propylene as an example, the propylene concentration in the raw material gas is 3 to 15% by volume, the ratio of molecular oxygen to propylene is 1 to 3, and the rest is nitrogen, steam, carbon oxide, propane, and the like.

Air is advantageously used as a supply source of molecular oxygen. If necessary, oxygen-enriched air or pure oxygen can be used, and a one-pass method or a recycling method is used. The reaction temperature is from 250 ° C to 450 ° C, the reaction pressure is from normal pressure to 500kPa, the space velocity is from 500 to 3000h.
It is preferable to carry out in the range of ^-1 (STP).

In the case of gas-phase catalytic oxidation of isobutylene, the concentration of isobutylene in the raw material gas is 1 to 10% by volume, and the concentration of molecular oxygen with respect to isobutylene is 3 to 2%.
0% by volume, 0 to 60% by volume of steam, and the balance is nitrogen, steam, carbon oxide, and the like. Air is advantageously used as a supply source of molecular oxygen, but oxygen-enriched air or pure oxygen can be used as necessary. The reaction temperature is 2
The reaction is preferably carried out at a temperature of 50 to 450 ° C., a reaction pressure of normal pressure to 500 kPa and a space velocity of 300 to 5000 h ⁻¹ (STP).

Next, in order to form acrylic acid, the above-mentioned oxide catalyst (second-stage catalyst) was charged into each tube of the bundle of tubes in the shell and placed in a second heat-exchange type multi-tube reactor. A mixed gas obtained by adding secondary air, secondary oxygen or water vapor as necessary to the obtained acrolein-containing gas is reacted at a reaction temperature (reactor heating medium temperature) of 100 to 380 ° C, preferably 150 to 350 ° C. Space velocity 300 ~ 5
000 hr ^-1 (STP), and a second-stage reaction is performed to obtain acrylic acid.

An oxide catalyst containing molybdenum and phosphorus for producing methacrylic acid (second-stage catalyst)
Into the heat exchange type multitubular second reactor in which each tube of the tube bundle portion in the shell is filled with the methacrolein-containing gas obtained in the preceding reaction, as required, with secondary air, secondary oxygen or The mixed gas obtained by adding steam is reacted at a reaction temperature (reactor heating medium temperature) of 100 to 380 ° C, preferably 150 to 350 ° C.
And at a space velocity of 300 to 5,000 hr ^-1 (STP), and a second-stage reaction is performed to obtain methacrylic acid.

The present invention can be applied to a reactor in which upper and lower chambers are formed by an intermediate tube sheet.

Next, an application to a reactor in which upper and lower chambers are formed by an intermediate tube sheet will be described with reference to FIG. FIG. 8 is an explanatory view showing an example of a longitudinal section of the reactor of the present invention. The reactor has two chambers A and B. A large number of reaction tubes 4 are loaded inside a reactor shell 1 having a circular cross-sectional shape, and each reaction tube is connected to a lower tube plate 6a at its lower end and to an upper tube plate 6b at their upper end.
It is fixed by a known method such as a pipe expansion method or welding.
In addition, it is preferable to provide a passage from the bottom to the top of the heating medium without disposing the reaction tube 4 in the center of the reactor shell 1 and to efficiently move the heating medium also in the center. Further, the shell side of the reactor shell 1 is vertically partitioned by an intermediate tube plate 8 substantially at an intermediate position between the upper end and the lower end of the reaction tube 4 to form two chambers A and B.

As shown in the figure, a plurality of perforated disk-shaped baffles 2 are provided in the chambers A and B in FIG. 8 to disperse the heat medium in the horizontal direction and reduce the temperature distribution in the horizontal direction. Are provided alternately. In the present invention, it goes without saying that there are reaction tubes 4 that are not supported by the perforated disc-shaped baffle 2 or the disc-shaped baffle 3 disposed in each chamber. Further, the reaction tube is held at a center interval of 1.2 to 1.4 times the outer diameter of the reaction tube. 4a is a reaction tube that is not supported by the perforated disk-shaped baffle plate 2.
The reaction tube not supported by the disk-shaped baffle plate 3 is indicated by 4b.

FIG. 9 is an enlarged explanatory view of a cross section of a contact portion between the reaction tube and the intermediate tube plate. The reaction tube 4 and the intermediate tube sheet 8 are preferably made of the same material such as steel in consideration of expansion and contraction due to heating and cooling.

In the reaction tube 4, a catalyst may be used as a fixed bed and the catalyst may be filled according to the purpose of the reaction. For example, a propylene-containing gas is subjected to a two-stage catalytic gas phase oxidation reaction to produce acrylic acid. As the upstream catalyst, an oxidation catalyst generally used for producing acrolein by performing a gas phase oxidation reaction of a propylene-containing raw material gas can be used. Similarly, the downstream catalyst is not particularly limited, and is generally used for producing acrylic acid by vapor-phase oxidation of a reaction gas containing mainly acrolein obtained on the upstream side by a two-stage catalytic gas phase oxidation method. Any of the known oxidation catalysts can be used.

As the upstream catalyst, the preceding catalyst for producing acrylic acid can be used, and as the downstream catalyst, the latter catalyst for producing acrylic acid can be used.

The catalysts constituting the upstream catalyst layer and the downstream catalyst layer do not need to be single catalysts. For example, a plurality of kinds of catalysts having different activities are charged in order, May be diluted with an inert material such as an inert carrier. The same applies to other catalysts described below.

The shape of the catalyst is not particularly limited, and may be Raschig ring, sphere, column, ring, and the like. The molding method may be carrier molding, extrusion molding, tablet molding, or the like. Further, a form in which these catalyst substances are supported on a refractory carrier is also useful.

Here, the method of filling the catalyst in the reactor in which the upper and lower chambers are formed by the intermediate tube sheet and the form of filling the catalyst will be described.

First, before filling the catalyst, a wire mesh and a receiver 14 are installed at the lower end of the reaction tube 4 to prevent the catalyst from dropping. Before the catalyst is filled, if necessary, a refractory 22 inert to the reaction is filled, and the upstream catalyst 21 is filled in the reaction tube 4. Next, the downstream catalyst 23 is charged. A space between the upstream catalyst 21 and the downstream catalyst 23 may be filled with a refractory 22 inert to the reaction.

In FIG. 8, the catalyst filling is omitted for clarity of the drawing, but FIG. 9 shows an example of the catalyst filling for one reaction tube. As shown in FIG. 9, the lower part of the B timbre region is filled with an inert refractory 22, then with the upstream catalyst 21, and further from the upper part, the intermediate tube sheet 8 is filled.
Inert refractory 2 to the A chamber area through
2 and the downstream side catalyst 23 is added to the remaining A chamber region.
Fill. When the temperature of the B chamber is higher than that of the A chamber, the raw material gas is partially oxidized by the upstream catalyst 21, then cooled at the inert refractory 22, and then cooled at the downstream catalyst 23. Further partial oxidation is performed while maintaining the temperature to produce the desired product. Therefore,
In the A chamber region, the portion of the inert refractory 22 corresponds to a cooling layer, and the downstream catalyst 23 corresponds to a reaction layer.

Examples of the inert refractory include α-alumina, alundum, mullite, carborundum, stainless steel, silicon carbide, steatite, pottery, porcelain, iron and various ceramics.

The inert refractory is, for example, granular and does not need to be uniformly filled over the entire inert refractory layer. However, in order to effectively cool the reaction gas, the inert refractory layer is used. It is preferred to fill substantially uniformly throughout. The same applies to an inert refractory having a shape other than granular.

One of the functions of the inert refractory layer is that when the temperature of the A chamber is lower than the temperature of the B chamber, the product-containing gas from the upstream catalyst is rapidly cooled to be suitable for the oxidation reaction in the downstream catalyst layer. The point is to adjust the temperature of the reaction gas within the temperature range. For this reason, it is necessary to provide the inert refractory layer so as to have a length that can sufficiently exhibit the above-described function.

Therefore, in the present invention, the inert refractory layer in the vicinity of the central tube sheet has a length sufficient to cool the reaction gas from the upstream catalyst layer to a temperature suitable for the downstream catalyst layer, and furthermore, the upstream refractory layer has a sufficient length. It is preferable that both the catalyst at the outlet of the side catalyst layer and the catalyst at the inlet of the downstream catalyst layer are arranged so as not to be substantially affected by heat from the intermediate tube sheet. In this regard, in the present invention, since the transfer of the heat medium between the chambers is reduced and the heat effect can be reduced, the length of the inert refractory layer can also be shortened. Therefore, the length of the reaction tube filled with the catalyst layer, that is, the height of the reactor can be reduced, and a simple device can be obtained.

Specifically, the length of the inert refractory layer is determined by the temperature of the reaction gas entering the downstream catalyst layer from the inert refractory layer,
That is, when the temperature of the reaction gas at the downstream catalyst layer inlet is (when the heat medium flows in parallel with the raw material or product gas,
It is sufficient that the length is sufficient to cool the heating medium inlet temperature + 15 ° C. or less.

Another function of the inert refractory layer is that when the reaction gas from the upstream reaction layer passes, impurities contained in the reaction gas, for example, in the case of production of acrylic acid, sublimation from the upstream catalyst. In addition to preventing pressure loss due to molybdenum components and high-boiling substances such as terephthalic acid as a byproduct, these impurities also prevent the impurities from directly entering the downstream catalyst layer and deteriorating the catalyst performance. It is in.
For this function only, the porosity of the inert refractory may be reduced, but if it is too low, the pressure loss increases, which is not preferable. Therefore, in the present invention,
The porosity of the inert refractory layer is usually 40 to 99.5%,
Preferably, it is 45 to 99%. The “porosity” is defined by the following equation: Porosity (%) = {(XY) / X} × 100 where X: volume of inert refractory layer Y: inert refractory The actual volume of the object (the actual volume, for example, in the case of a ring, means the actual volume excluding its central space).

When the porosity is less than 40%, the pressure loss increases. On the other hand, when the porosity exceeds 99.5%, the function of trapping impurities and the function of cooling the reaction gas are undesirably reduced.

The inert refractory is used for preheating the raw material gas.
Insertion at the inlet of the upstream catalyst is preferable because it leads to an improvement in the yield of the product.

The filling of the catalyst in the reaction tubes does not matter whether each reaction tube is supported by a disk-type baffle plate or a perforated disk-type baffle plate. Therefore, the reactor shell 1
Regardless of the reaction tube, any one filled with a catalyst can be used.

Next, with reference to FIG. 8, the flow of a heat medium in the case of producing acrylic acid using a reactor in which upper and lower chambers are formed by an intermediate tube sheet will be described. Known conditions for obtaining acrolein from propylene can be applied to the raw material gas and the inert gas supplied to the chamber B, the catalyst to be charged, the reaction temperature, and the like. Known conditions for obtaining acrylic acid from acrolein can be applied to the gas, the catalyst to be charged, the reaction temperature, and the like. For this reason, the flow of the heat medium introduced into each chamber, which is a special feature, will be described here. In FIG. 8, the raw material gas is supplied from the lower part of the reactor, is brought into contact with the catalyst to obtain a product, and the product is discharged from the upper part of the reactor.
The case where the heating medium in B and B flows in the upflow.

First, in the chamber B where the first-stage reaction is performed, the heat is introduced into the chamber B from the heat medium discharge port 34 of the pump 35 through the lower tubular conduit 11a provided on the outer periphery of the reactor shell 1. The heat medium enters the shell 1 from almost the entire circumference of the inner periphery of the reactor by the tubular conduit 11a, and then contacts the reaction tube 4 to absorb the reaction heat generated by the catalytic reaction. The baffle 2 and the disc-shaped baffle 3 move toward the upper part of the reactor while changing the flow path.
At this time, the heat medium rises at the perforated portion of the perforated disk-shaped baffle plate 2, but the reaction tube is held at a center interval of 1.2 to 1.4 times the outer diameter of the reaction tube. Sufficient heat exchange is performed even in the reaction tube 4a that is not supported by the perforated disk-shaped baffles. Next, the heat medium absorbs the reaction heat while being in contact with the reaction tube 4 and travels substantially horizontally along the disc-shaped baffle plate 3 toward substantially the entire inner peripheral portion of the reactor. As a result, the reaction tube is held at a center interval of 1.2 to 1.4 times the outer diameter of the reaction tube, so that sufficient heat exchange is performed even in the reaction tube 4b not supported by the disk-shaped baffle plate 3. , Rising from the outer peripheral portion of the disk-shaped baffle plate 3. Then, the heat medium that has reached the upper part of the reactor shell 1 is discharged from the heat medium circulation port 31 of the upper tubular conduit 11 a in the chamber B, and then cooled by the heat exchanger 24. The cooled heat medium enters the reactor shell 1 from the heat medium discharge port 34 of the pump via the lower tubular conduit 11a by using a known pump 35 such as a spiral pump or an axial flow pump, and repeats the above circulation. Although a gap may be provided between the perforated disk-shaped baffle plate 2 and the reactor shell 1, it is preferable to eliminate the gap for the purpose of reducing the temperature distribution of the heat medium in the reactor. The reaction gas can be supplied from the upper portion of the reactor by changing the order of charging the catalyst. In the chamber A, the heat medium is circulated in the same manner as in the chamber B. Further, as a method of circulating the heat medium, if necessary, one or both of AB can be circulated in the reverse direction.
However, from the viewpoint of protecting the pump 35, after the heat medium becomes relatively low temperature through the heat exchanger 24, the pump 3
5 is preferred.

According to the present invention, maleic anhydride is produced by a known catalyst and reaction system using benzene or butane as a raw material gas, and phthalic anhydride is produced by a known catalyst and reaction system using xylene and / or naphthalene as a raw material gas. You can also.

As the heat medium circulated in the reactor shell 1, any conventionally known heat medium can be used. For example, a phenyl ether-based heat medium which is a molten salt, a night game, or a Dowsome organic heat medium is used. Can be.

According to the present invention, the power energy can be reduced by arranging the space in the center of the reactor shell and the reaction tube which is not supported by the perforated disk-type baffle plate. The selectivity and yield can be adjusted.
Moreover, since the hot spots in the reaction tube can be reduced uniformly, the catalyst can be efficiently prevented from being deteriorated, and the catalyst life can be extended.

[0087]

The present invention will now be described more specifically with reference to examples.

(Production example 1 of catalyst) 100 kg of ammonium molybdate while heating and stirring 150 liters of pure water
6.3 kg of ammonium paratungstate and 27.5 kg of nickel nitrate were dissolved. Separately, 68.7 kg of cobalt nitrate was added to 100 liter of pure water.
Pure water is obtained by adding 19 kg of ferric nitrate to 30 liters of pure water, and adding 22.9 kg of bismuth nitrate and 6 liters of concentrated nitric acid.
After dissolving in 1 liter, a nitrate aqueous solution prepared by mixing was added dropwise. Subsequently, 20 mass% silica sol solution 1
A solution prepared by dissolving 4.2 kg and 0.38 kg of potassium nitrate in 15 liters of pure water was added. The suspension thus obtained was heated and stirred, evaporated to dryness, and then dried and pulverized. The obtained powder is formed into a cylindrical shape having a diameter of 5 mm,
The catalyst was obtained by calcination at 60 ° C. for 6 hours under flowing air. The molar composition of the catalyst was Mo12, Bi1.0, Fe1.
0, Co5, Ni2.0, W0.5, Si1.
0, K 0.08.

(Production Example 2 of Catalyst) While heating and stirring 500 liters of pure water, 100 k of ammonium molybdate was added.
g, 19.1 kg of ammonium paratungstate and 30.4 kg of ammonium metavanadate were added and dissolved. To this solution was added a solution in which 20.5 kg of copper nitrate and 3.4 kg of antimony trioxide were separately added to 50 liter of pure water. Further, 350 kg of a silica-alumina carrier having an average particle diameter of 5 mm was added to the mixed solution, and the mixture was evaporated to dryness to support the catalyst component on the carrier, and calcined at 400 ° C. for 6 hours to obtain a catalyst. By repeating this, a predetermined amount of catalyst was obtained. The molar composition of the catalyst is Mo 12, V 5.5, W
1.5, Cu 1.8, and Sb 0.5.

Example 1 Using the reactor shown in FIG.
5.6 m ^{3 of} a catalyst for mainly producing acrolein from propylene was charged into the reaction tube obtained in the above catalyst production example 1,
A raw material gas of 70.4 vol% of propylene 7 vol%, oxygen 12.6 vol%, steam 10 vol%, nitrogen and the like was introduced so that the catalyst contact time was 2 seconds. As a heat medium, a heat medium composed of 50% by mass of potassium nitrate and 50% by mass of sodium nitrite was circulated at an inlet temperature of 315 ° C. with an axial pump of 2900 m ³ / h. In the reactor, there are reaction tubes that are not supported by the perforated disk-shaped baffles and reaction tubes that are not supported by the disk-shaped baffles.

When the product from the reactor product outlet was actually measured, the propylene conversion was 97.0% and the acrolein selectivity was 84.8%. Further, when estimated by simulation, the propylene conversion was 97.1%, and the acrolein selectivity was 84.7%, and almost traces could be obtained.

Comparative Example 1 The propylene reaction rate and the acrolein selectivity were simulated in the same manner as in Example 1 except that the hole diameter of the perforated disk-shaped baffle plate was changed to the diameter shown in Table 1. did. Table 1 shows the results. As a result, there is no change in selectivity and yield, and the axial pump power is 5.4.
Increased by a factor of two. In the reactor, there are no reaction tubes that are not supported by the perforated disc-shaped baffles, and there are reaction tubes that are not supported by the disc-shaped baffles.

(Comparative Example 2) As a reactor having no reaction tube which is not supported by a perforated disk-shaped baffle, the hollow diameter shown in Table 1 and the hole diameter of the perforated disk-type baffle were changed. Acrolein was obtained in the same manner as in Example 1. Table 1 shows the results. In the reactor, there are no reaction tubes that are not supported by the perforated disc-shaped baffles, and there are reaction tubes that are not supported by the disc-shaped baffles. As a result, the axial flow pump power increased 1.8 times without any change in selectivity and yield.

(Example 2) Except that the diameter of the perforated disk-type baffle plate and the diameter of the central space were the same as those in Example 1, and the diameter of the disk-type baffle plate and the diameter of the reactor shell were set to the values shown in Table 1, respectively. Acrolein was obtained in the same manner as in Example 1. Table 1 shows the results. In the reactor, there are reaction tubes that are not supported by the perforated disc-shaped baffles, but there are no reaction tubes that are not supported by the disc-shaped baffles. As a result, the axial pump power ratio is:
0.97.

Comparative Example 3 Acrolein was obtained by operating under the same conditions as in Example 2 except that the hole diameter of the perforated disk-shaped baffle was changed to the value shown in Table 1. Table 1 shows the results. In the reactor, there are no reaction tubes not supported by the perforated disc-shaped baffle and no reaction tubes supported by the disc-shaped baffle.

Example 3 Using the reactor shown in FIG.
Length of one reaction tube is 7m, inner diameter 25mm, outer diameter 29m
m, having 4100 reaction tubes made of steel, having an intermediate tube plate, and using the catalyst of Catalyst Production Example 1 as the first-stage catalyst and the catalyst of Catalyst Production Example 2 as the second-stage catalyst. Example 1 shows the reactor body diameter, central space diameter, disk type baffle diameter, perforated disk type baffle hole diameter, hollow area / body area, disk area / body area, and perforated area / body area. The reactor was operated using a single reactor identical to Table 1 shows the results.

Comparative Example 4 The same conditions as in Example 3 were used except that the diameter of the reactor body, the diameter of the disk-shaped baffle, and the hole diameter of the perforated disk-shaped baffle were changed to the values shown in Table 1. Operated. Table 1 shows the results. In the reactor, there are no reaction tubes not supported by the perforated disc-shaped baffle and no reaction tubes supported by the disc-shaped baffle.

[0098]

[Table 1]

[0099]

According to the arrangement of the reaction tube which does not support the perforated disk type baffle area, the axial pump power can be reduced to 1 / 5.4. Moreover, the axial pump power can be reduced without changing the selectivity or the yield of the target product.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a conventional multitubular reactor.

FIG. 2 is a diagram showing a perforated disk-shaped baffle, a disk-shaped baffle, a reaction tube, and a space portion of the reactor of the present invention.

FIG. 3 is a diagram showing a circulation path of a heat medium in a reactor having a circulation device.

FIG. 4 is a schematic diagram of a reactor that takes out a heat medium from a part of the circulation device and introduces the cooled heat medium into the circulation device.

FIG. 5 is a view showing an opening row of an annular conduit.

FIG. 6 is a diagram showing a flow of a heat medium in a reactor when the heat medium flows downflow.

FIG. 7 is a view showing an arrangement of gas outlets in an upper tube sheet part.

FIG. 8 is an explanatory view of an example of a longitudinal section of a two-chamber catalytic gas phase oxidation reactor of the present invention.

FIG. 9 is an enlarged explanatory view of a cross section of a catalyst layer in a reaction tube and an intermediate tube plate in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Reactor shell 2 ... Perforated disk type baffle plate 3 ... Disk type baffle plate 4 ... Reaction tube 4a ... Reaction tube not supported by a perforated disk type baffle plate 4b ... Reaction not supported by a disk type baffle plate Tubes 5, 21, 23 ... Catalyst 6a ... Lower tube sheet 6b ... Upper tube sheet 7 ... Tie rod 8 ... Central tube sheet 10, 10a, 10b ... Heat medium 11a, 11b ... Annular conduit 12 ... Heat medium outlet 13 ... Heat medium Discharge pot 14 ... Nozzle 15, 16 ... Conduit for gas discharge 17 ... Nozzle 18 ... Receiver 22 ... Inert refractory 24 ... Heat exchanger 30 ... Circulation device 31 ... Heat medium circulation port 32,32 '... Heat medium introduction port 33 ... stirring blade 34 ... heat medium discharge port 35 ... pump 36 ... nozzle 37 ... partition plate 50 ... raw material supply port 51 ... product discharge port φ1 ... perforated disk type baffle plate hole diameter φ2 ... disk type baffle plate diameter φ3… Reactor shell inner diameter φ4… Space part diameter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C07C 47/22 C07C 47/22 Z 51/25 51/25 57/05 57/05 (72) Inventor Kitaura Shoji 1 992, Nishioki, Okihama-shi, Abashiri-ku, Himeji-shi, Hyogo Japan Nippon Shokubai Co., Ltd. 1 Nippon Shokubai Co., Ltd. at 992, Nishioki, Okihama-sha, Aboshi-ku, Himeji-shi

Claims (10)

[Claims] 1. A cylindrical reactor shell having a plurality of annular conduits for introducing or discharging a heating medium in a radial direction disposed on an outer periphery thereof and having a raw material supply port and a product discharge port; A circulating device to be connected, a plurality of reaction tubes holding the reactor by a plurality of tubesheets, and a perforated disk-type baffle plate for changing the direction of the heat medium introduced into the reactor shell. In a multitubular reactor having a disc-shaped baffle plate in the longitudinal direction of the reaction tube, the reaction tube is held at a center interval of 1.2 to 1.4 times the outer diameter of the reaction tube, and the reaction is carried out. A reactor for catalytic gas phase oxidation reaction comprising: a space in which no reaction tubes are arranged in the center of a vessel shell; and a reaction tube that is not supported by a perforated disk-shaped baffle plate. 2. The reactor according to claim 1, further comprising a reaction tube that is not supported by the disc-shaped baffle. 3. The cross-sectional area of the space is 0.5 to 5% of the cross-sectional area of the reactor shell, the cross-sectional area of the disc-shaped baffle is 50 to 95% of the cross-sectional area of the reactor, and The reactor according to claim 1 or 2, wherein the perforated disk-shaped baffle has a cross-sectional area of 2 to 25% of the cross-sectional area of the reactor. 4. The cooling medium introduction port according to claim 1, wherein the heating medium circulation port of the annular conduit or the circulation device discharged from the reactor shell has a cooling medium introduction port. The reactor as described. 5. A gas discharge conduit for discharging gas accumulated in the reactor shell together with the heating medium into the reactor shell and discharging the gas to the outside of the reactor shell.
5. The reactor according to any one of the above items 4. 6. The annular conduit has a plurality of rows of openings through which the heat medium penetrates, wherein the width of the openings is 5 to 50% of the center interval,
The reactor according to any one of claims 1 to 5, wherein the value of opening length / opening width is in the range of 0.2 to 20. 7. The reactor according to claim 6, wherein at least one of the rows of openings has two or more openings. 8. The apparatus according to claim 1, further comprising one or more shielding plates for partitioning the inside of the reactor shell into two or more closed spaces in the longitudinal direction of the reaction tube. A reactor according to item 6. 9. The reactor according to claim 1, which is used for producing (meth) acrylic acid or (meth) acrolein. 10. A method for producing (meth) acrylic acid and / or (meth) acrolein using the reactor according to any one of claims 1 to 9.