N-methylaniline gas phase reactor capable of resisting catalyst pulverization

Abstract

The invention belongs to the technical field of fine chemical synthesis, and particularly relates to an N-methylaniline gas phase reactor for resisting catalyst pulverization. The reactor comprises an upper sealing head (1), a cylinder body (11) and a lower sealing head (2) which are sequentially arranged from top to bottom, a reaction gas inlet (7) is formed in the upper sealing head (1); the lower sealing head (2) is provided with a reaction gas outlet (13) and a supporting plate (12); tube plates are arranged on the upper portion and the lower portion of the barrel body (11), and column tube bundles (14) composed of a plurality of column tubes are arranged between the tube plates. Free liquid formed by cooling in the entrainment or flowing process is captured by the ceramic balls in the filter cartridge, the free liquid is prevented from falling into a catalyst bed layer through the flow guide pipe, reaction gas is guided and uniformly distributed, and the liquid collected on the ceramic balls is continuously discharged through the drainage pipe and the baffle, so that the continuous production of the device is not influenced, and the production efficiency is improved. Direct contact between free liquid and the catalyst is effectively avoided, and the anti-catalyst pulverization effect is obvious.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemical synthesis, relates to N-methylaniline synthesis technology, and specifically is a N-methylaniline gas phase reactor that resists catalyst pulverization. Background Art

[0002] N-methylaniline has excellent anti-explosion properties and is an important intermediate widely used in the fields of medicine, pesticides and dyes. The methods for synthesizing N-methylaniline are mainly divided into liquid phase synthesis and gas phase synthesis. Liquid phase synthesis uses strong acid as a catalyst, which causes corrosion of reaction equipment, environmental pollution and excessive by-products that are not suitable for separation, so it is gradually replaced by gas phase synthesis.

[0003] The gas phase synthesis method uses an environmentally friendly solid catalyst and methanol as an alkylating agent to catalyze aniline to synthesize N-methylaniline under low-pressure gas phase conditions in a fixed bed reactor. The reaction uses a Cu-based catalyst, and the single-pass conversion rate of aniline is high (more than 90%) and the selectivity of N-methylaniline is good (more than 94%), but the reaction has the following problems:

[0004] 1) The catalyst is sensitive to free liquid, and contact with the free liquid phase can easily lead to catalyst powderization and deactivation.

[0005] 2) The aniline raw material contains high-boiling point substances. The thermal sensitivity of aniline makes it easy to coke. Aniline itself has a high boiling point and is easy to liquefy, which increases the risk of free liquid phase entering the catalyst bed.

[0006] 3) The reaction process involves alternating heating and cooling conditions. To ensure the stability of the catalyst bed temperature, sufficient heat needs to be added or removed.

[0007] At present, the reactors for N-methylaniline are:

[0008] Serial number name Rights Unit 5 An improved N-methylaniline reaction device Changzhou Baolong Chemical Co., Ltd. 6 Reactor for N-methylaniline reaction device Changzhou Baolong Chemical Co., Ltd. 10 An emergency venting safety device for N-methylaniline reaction with good condensation effect Changzhou Baolong Chemical Co., Ltd. 11 A safety device for emergency venting of N-methylaniline reaction Changzhou Baolong Chemical Co., Ltd.

[0009] One of the reactors for the N-methylaniline reaction device mainly provides a coil-type heat exchange reactor, which only provides a heat transfer pathway and does not solve the problem of catalyst pulverization that may be caused by the free liquid phase. An improved N-methylaniline reaction device mainly describes an N-methylaniline reactor and process flow, but does not propose a targeted solution for the alternating heating and cooling conditions in the reactor reaction process. Other related patents all propose effective solutions to the pain points of N-methylaniline gas phase synthesis.

[0010] Most of the literature published on N-methylaniline focuses on reaction mechanism and catalyst research, and there are relatively few studies specifically targeting N-methylaniline reactors.

[0011] Under the above research background, how to solve the above mentioned problems becomes the key research content of the present invention. Summary of the invention

[0012] The object of the present invention is to provide a catalyst pulverization resistant N-methylaniline gas phase reactor in view of the technical problems in the prior art. The reactor is a novel reactor designed according to the characteristics of the N-methylaniline synthesis process and has reliability, continuous operation and stable operation.

[0013] In order to achieve the purpose of the present invention, the specific technical scheme of the present invention is as follows:

[0014] A gas phase reactor for N-methylaniline that resists catalyst pulverization comprises a shell, wherein the shell is provided with an upper head, a cylinder, and a lower head in sequence from top to bottom. The upper head and the lower head are connected to the cylinder by flanges. The upper head is provided with a reaction gas inlet, and the lower head is provided with a reaction gas outlet and a porcelain ball support plate. The upper and lower parts of the cylinder are provided with tube sheets (wherein the upper part of the cylinder is tube sheet one, and the lower part is tube sheet two), and a tube bundle is provided between the tube sheets, the tubes are filled with catalysts, and the catalyst bed in the tubes is heated or cooled by heat transfer oil outside the tube bundle, and the upper and lower tube sheets are provided with through holes for the tube bundle to pass through, the upper end of the tube bundle is connected to the upper head, and the lower end of the tube bundle is connected to the lower head, and the two ends of the tube bundle are sealed and connected to the upper and lower tube sheets. The upper tube plate is provided with baffles, and an insulating reaction bed is provided between the baffles. An integrally detachable conical bottom filter cartridge with a support is provided between the baffles of the upper tube plate. Ceramic balls and ceramic rings are filled in the filter cartridge for entrained liquid phase filtration to prevent liquid foam from entering the catalyst bed layer, which would cause the catalyst to be pulverized and deactivated.

[0015] Furthermore, ceramic balls are filled between the lower head ceramic ball support plate and the lower head flange as catalyst proppants for the tube bundle, and can also adsorb heavy components produced by the reaction to prevent the heavy components from entering the downstream heat exchanger and adhering to the heat exchanger tube wall, resulting in reduced heat exchange efficiency or even blockage.

[0016] Furthermore, the lower head is provided with a lifting lug for head disassembly and lifting, ensuring that the lower head can be disassembled through the flange and completely separated from the cylinder body, so as to facilitate the disassembly and replacement of the porcelain ball in the lower head.

[0017] Furthermore, the upper end cap is provided with a manhole for loading porcelain balls into the cone-bottom filter cartridge and a lifting lug for disassembling and lifting the end cap, ensuring that the upper end cap is completely separated from the cylinder body after disassembly, facilitating the removal and replacement of porcelain balls in the cone-bottom filter cartridge. The provision of the manhole facilitates the loading and compaction of porcelain balls at the upper conical surface of the reaction gas inlet.

[0018] Furthermore, the diameter of the reaction gas inlet of the upper head gradually increases after entering the head, and the bottom of the reaction gas inlet is lower than the upper edge of the cone-bottom filter cartridge, and is buried in the porcelain balls filled in the cone-bottom filter cartridge, ensuring that the reaction gas enters the porcelain ball layer and effectively filters the liquid foam that may be entrained through the porcelain balls, while preventing the reaction gas from blowing away the porcelain balls and affecting the filtering effect.

[0019] Furthermore, the upper edge of the cylinder of the cone-bottom filter cartridge is in contact with the upper head, the upper part of the cylinder part is opened with holes for gas circulation, and the lower part of the cylinder part is provided with a liquid drainage pipe near the contact part with the cone bottom, and the drainage pipe extends to the outside of the baffle; there is a through hole on the cone bottom for the cylindrical guide pipe bundle to pass through, the guide pipe bundle is sealed and connected to the cone bottom, the lower section of the guide pipe wall has no holes, the upper section of the guide pipe wall has holes for gas circulation, and the top of the guide pipe has no holes.

[0020] Furthermore, the upper edge of the baffle does not abut against the cone bottom of the cone bottom filter cartridge, and is used for gas circulation. The tube bundle in the cartridge is only arranged within the range between the baffles, and no tubes are arranged in the cartridge outside the baffles. A drainage port is arranged on the outside of the baffle, near the upper tube plate, and the height of the drainage port is lower than the upper edge of the baffle.

[0021] Furthermore, baffles are provided between the tube bundles in the cylinder, and a heat transfer oil inlet and a heat transfer oil outlet are provided on the cylinder at the upper part of the lower tube plate (tube plate 2) and the lower part of the upper tube plate (tube plate 1), respectively.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (I) In view of the problem that the N-methylaniline synthesis catalyst is sensitive to free liquid and is easily pulverized when in contact with free liquid, the free liquid entrained or formed by cooling during the flow is captured by the ceramic balls in the filter cartridge, and the free liquid is prevented from falling into the catalyst bed through the guide pipe. At the same time, the reaction gas is guided to make the reaction gas evenly distributed, and the liquid collected on the ceramic balls is continuously discharged through the guide pipe and baffle, which does not affect the continuous production of the device, effectively avoids direct contact between free liquid and catalyst, and has a significant effect on resisting catalyst pulverization. In view of the heating and exothermic environment of the N-methylaniline reaction, a heat exchange tube with baffles is used to enhance the heat exchange effect between the heat transfer oil and the reaction gas, and ensure the stability of the catalyst bed temperature.

[0024] (ii) The filter cartridge at the top of the reactor can effectively filter free liquid entrained by the reaction gas or formed by cooling, preventing the entrained liquid from contacting the catalyst and causing the catalyst to pulverize.

[0025] (III) Since the bottom of the cone-bottom filter cartridge is connected to the cone-bottom filter cartridge but has no holes at the bottom and top and holes on the upper side, even if free liquid is enriched on the surface of the porcelain ball, it will not fall onto the catalyst surface below the filter cartridge, but will flow along the wall of the guide pipe to the bottom of the cone of the filter cartridge, and flow along the slope of the cone bottom to the drainage pipe, and be discharged to the outside of the upper tube plate baffle through the drainage pipe.

[0026] (iv) The reaction gas in the reactor pipeline and the heat transfer oil outside the pipeline fully exchange heat, which can effectively replenish or remove heat.

[0027] (V) The present invention has the beneficial effects of extending the service life of the catalyst, increasing the output of N-methylaniline per unit catalyst, reducing the frequency of shutdown and maintenance of the device, and increasing the production and efficiency of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic structural diagram of an N-methylaniline gas phase reactor that is resistant to catalyst pulverization according to an embodiment of the present invention.

[0029] Figure 2 This is a top view of the upper tube plate of a cylinder of an N-methylaniline gas phase reactor that is resistant to catalyst pulverization according to an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of a bottom draft tube of a filter cartridge of an N-methylaniline gas phase reactor that resists catalyst pulverization according to an embodiment of the present invention.

[0031] Reference numerals:

[0032] 1-upper head, 2-lower head, 3-flange, 4-filter cartridge, 5-guide pipe, 6-1 upper lifting ear, 6-2 lower upper lifting ear, 7-reaction gas inlet, 8-guide pipe, 9-ceramic ball and ceramic ring, 10-baffle, 11-cylinder, 12-ceramic ball support plate, 13-reaction gas outlet, 14-tube bundle, 15-baffle, 16-insulated reaction bed, 17-drain port, 18-tube sheet 1, 19-tube sheet 2, 20-manhole, 21-heat transfer oil outlet, 22-heat transfer oil inlet. DETAILED DESCRIPTION

[0033] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0034] Any feature disclosed in this specification (including claims and abstract), unless otherwise stated, may be replaced by other equivalent or alternative features having similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0035] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0036] Embodiment 1:

[0037] like Figure 1As shown, a gas phase reactor of N-methylaniline with resistance to catalyst pulverization of the present invention comprises a shell, wherein the shell is provided with an upper head 1, a lower head 2, and a cylinder 11 in sequence from top to bottom. The upper head 1 and the lower head 2 are connected to the cylinder by a flange 3.

[0038] The upper end cap 1 is provided with a reaction gas inlet 7; the lower end cap 2 is provided with a reaction gas outlet 13 and a porcelain ball support plate 12. The upper and lower parts of the cylinder 11 are provided with tube sheets (the upper part is tube sheet 18, and the lower part is tube sheet 2 19), and a tube bundle 14 composed of tubes is provided between the tube sheets. The tubes are filled with catalysts, and the catalyst bed in the tubes is heated or cooled by heat transfer oil outside the tube bundle 14. The upper and lower tube sheets are provided with through holes for the tube bundle 14 to pass through. The upper end of the tube bundle 14 is connected to the upper end cap 1, and the lower end of the tube bundle 14 is connected to the lower end cap 2. The two ends of the tube bundle 14 are sealed and connected to the upper and lower tube sheets. The upper tube plate is provided with baffles 15, between the baffles 15 is an adiabatic reaction bed 16, and the adiabatic reaction bed 16 is an adiabatic catalyst; between the baffles 15 of the upper tube plate is an integrally detachable conical bottom filter cartridge 4 with a support, and the conical bottom filter cartridge 4 is filled with ceramic balls and ceramic rings 9 for entrained liquid phase filtration.

[0039] Ceramic balls are filled between the lower head 2, the ceramic ball support plate 12 and the flange of the lower head 2 as catalyst proppants for the tube bundle, and can also adsorb the heavy components produced by the reaction to prevent the heavy components from entering the downstream heat exchanger and adhering to the heat exchanger tube wall, resulting in reduced heat exchange efficiency or even blockage.

[0040] The lower head 2 is provided with a lifting lug 6 for lifting the head after disassembly, so as to ensure that the lower head 2 can be lifted easily after the flange is disassembled and completely separated from the cylinder 11, and the porcelain ball in the lower head 2 can be removed and replaced easily.

[0041] The upper end cap 1 is provided with a manhole 20 for loading porcelain balls into the cone bottom filter cartridge 4 and a lifting lug 6 for disassembling and hoisting the end cap, ensuring that the upper end cap 1 is completely separated from the cylinder 11 after being disassembled and hoisted, so as to facilitate the disassembly and replacement of the porcelain balls and rings 9 in the cone bottom filter cartridge 4. The provision of the manhole 20 facilitates the loading and compaction of the porcelain balls and rings 9 at the upper conical surface of the reaction gas inlet 7.

[0042] The diameter of the reaction gas inlet 7 of the upper head 1 gradually increases after entering the head, and the bottom of the reaction gas inlet 7 is lower than the upper edge of the cone-bottom filter cartridge 4, and is buried in the porcelain balls and porcelain rings 9 filled in the cone-bottom filter cartridge 4, ensuring that the reaction gas enters the porcelain ball layer and effectively filters the liquid foam that may be entrained through the porcelain balls, while preventing the reaction gas from blowing away the porcelain balls and affecting the filtering effect.

[0043] The upper edge of the cylinder of the cone bottom filter cartridge 4 is in contact with the upper end cap 1, and the upper part of the cylinder of the cone bottom filter cartridge 4 is provided with a hole for gas circulation, thereby reducing the flow resistance of the reaction gas; the lower part of the cylinder of the cone bottom filter cartridge 4 is provided with a liquid drainage pipe 8 near the contact part with the cone bottom, and the drainage pipe 8 extends to the outside of the baffle 15, and the drainage pipe 8 is used to drain the liquid adsorbed and gathered by the porcelain balls to the outside of the baffle 15 for discharge, thereby preventing free liquid from entering the catalyst bed; the cone bottom filter cartridge 4 has a through hole for the cylindrical guide pipe bundle to pass through, and the guide pipe 5 forms a guide pipe bundle and is sealed and connected to the cone bottom, and the lower section of the guide pipe 5 wall has no hole, and the upper section of the guide pipe 5 wall has a hole for gas circulation, and the top of the guide pipe 5 has no hole. The side opening of the guide pipe 5 can prevent the liquid adsorbed by the porcelain balls from dripping onto the catalyst surface, thereby causing the catalyst to pulverize.

[0044] The upper edge of the baffle 15 does not abut against the cone bottom of the cone bottom filter cartridge 4, and is used for gas circulation. The tube bundle in the cylinder body 11 is only arranged within the range between the baffles 15, and no tube is arranged in the cylinder body 11 outside the baffle 15; a drain port 17 is arranged on the cylinder body outside the baffle 15, near the upper tube plate, and the height of the drain port 17 is lower than the upper edge of the baffle 15. The liquid drained to the outside of the baffle 15 by the drainage pipe 8 is discharged out of the reactor through the drain port.

[0045] Catalysts are loaded in the tube bundle 14 in the cylinder 11, baffles 10 are arranged between the tube bundles 14, and heat transfer oil inlet 22 and heat transfer oil outlet 21 are respectively arranged on the cylinder 11 at the upper part of the lower tube plate and the lower part of the upper tube plate. After the reaction gas is filtered by the ceramic balls in the filter cartridge, it enters the catalyst bed in the tube bundle 14 for reaction, releases heat or absorbs heat to the outside, and the heat transfer oil outside the tube bundle 14 exchanges heat with the wall between the reaction gas to remove the heat of the reaction gas or provide heat for the reaction gas, and the baffles 10 strengthen the turbulence of the heat transfer oil and enhance the heat exchange effect.

[0046] In view of the problem that N-methylaniline synthesis catalyst is sensitive to free liquid and is easy to pulverize when in contact with free liquid, this reactor can effectively avoid direct contact between free liquid and catalyst, and can discharge the liquid continuously without affecting the continuous production of the device. It has a significant effect on preventing catalyst pulverization.

[0047] In view of the heating and exothermic environment of the N-methylaniline reaction, a heat exchange tube with baffles is used to enhance the heat exchange effect between the heat transfer oil and the reaction gas and ensure the stability of the catalyst bed temperature.

[0048] The above-mentioned embodiments only express the specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the protection scope of the present application. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the technical solution concept of the present application, and these all belong to the protection scope of the present application.

[0049] This background section is provided to generally present the context of the invention, and the work of the presently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither explicitly nor implicitly admitted to be prior art to the present invention.

Claims

1. A gas phase reactor for N-methylaniline which is resistant to catalyst pulverization, characterized in that: The reactor comprises a shell, wherein the shell is provided with an upper head (1), a cylinder (11) and a lower head (2) in sequence from top to bottom; the upper head (1) and the lower head (2) are connected to the cylinder (11) by flanges; the upper head (1) is provided with a reaction gas inlet (7); the lower head (2) is provided with a reaction gas outlet (13) and a support plate (12); a tube sheet 1 (18) is provided at the upper part of the cylinder (11), and a tube sheet 2 (19) is provided at the lower part; a tube bundle (14) consisting of a plurality of tubes is provided between the tube sheets; and tubes at the upper and lower parts are provided with a plurality of tubes. The plates are provided with through holes for the tube bundle (14) to pass through; the upper end of the tube bundle (14) is communicated with the upper end cap (1), and the lower end of the tube bundle (14) is communicated with the lower end cap (2); the two ends of the tube bundle (14) are sealedly connected to the upper and lower tube sheets; the upper tube sheet is provided with a baffle (15), and an insulating reaction bed is provided between the baffles (15); an integrally detachable conical bottom filter cartridge (4) with a support is also provided between the baffles (15) on the upper tube sheet; the conical bottom filter cartridge (4) is filled with ceramic balls and ceramic rings (9) for entrained liquid phase filtration.

2. The N-methylaniline gas phase reactor for resisting catalyst pulverization according to claim 1, characterized in that: Ceramic balls are filled between the support plate (12) in the lower head (2) and the flange of the lower head (2) as support agents for the catalyst in the tube bundle.

3. The N-methylaniline gas phase reactor for resisting catalyst pulverization according to claim 1, characterized in that: The lower head (2) is provided with a lifting lug (6) for disassembling and lifting the lower head.

4. The N-methylaniline gas phase reactor for resisting catalyst pulverization according to claim 1, characterized in that: The upper end cap (1) is provided with a manhole (20) for a cone-bottom filter cartridge (4) and for loading porcelain balls and porcelain rings (9), and a lifting lug for disassembling and lifting the upper end cap (1).

5. The N-methylaniline gas phase reactor for resisting catalyst pulverization according to claim 1, characterized in that: The diameter of the reaction gas inlet (7) on the upper end cap (1) gradually increases after entering the end cap, and the bottom of the reaction gas inlet (7) is lower than the upper edge of the conical filter cartridge (4) and is buried in the ceramic balls and ceramic rings (9) filled in the conical filter cartridge (4).

6. A gas phase reactor for N-methylaniline resistant to catalyst pulverization according to any one of claims 1 to 5, characterized in that: The upper edge of the cone-bottom filter cartridge (4) is in contact with the upper end cap (1); the upper part of the cone-bottom filter cartridge (4) is provided with a hole for gas circulation; a liquid drainage pipe (8) is provided at a lower part close to the contact part with the cone bottom; the drainage pipe (8) extends to the outside of the baffle (15); a through hole is provided on the cone bottom for a guide pipe bundle composed of cylindrical guide pipes (5) to pass through; the guide pipe bundle is sealed and connected to the cone bottom; the lower section of the pipe wall of the guide pipe (5) in the guide pipe bundle is not provided with a hole, the upper section is provided with a hole for gas circulation; the top of the guide pipe (5) in the guide pipe bundle is not provided with a hole.

7. The N-methylaniline gas phase reactor for resisting catalyst pulverization according to claim 6, characterized in that: The upper edge of the baffle (15) does not abut against the cone bottom of the cone bottom filter cartridge (4) for gas circulation; the tube bundle in the cylinder of the cone bottom filter cartridge (4) is arranged only within the range between the baffles (15), and no tubes are arranged in the cylinder outside the baffles (15); a liquid discharge port (17) is arranged on the cylinder outside the baffle (15) near the upper tube plate, and the height of the liquid discharge port (17) is lower than the upper edge of the baffle (15).

8. A gas phase reactor for N-methylaniline resistant to catalyst pulverization according to claim 1 or 7, characterized in that: Baffles are provided between the tube bundles (14) in the cylinder (11), a heat transfer oil inlet (22) is provided on the cylinder (11) above the second tube sheet (19), and a heat transfer oil outlet (21) is provided on the cylinder (11) below the first tube sheet (18).

9. The N-methylaniline gas phase reactor for resisting catalyst pulverization according to claim 8, characterized in that: Catalysts are loaded in the tubes of the tube bundle (14); and the catalyst bed in the tubes is heated or cooled by heat transfer oil outside the tube bundle (14).

10. The N-methylaniline gas phase reactor resistant to catalyst pulverization according to claim 8, characterized in that: The space between the baffles (15) is an adiabatic reaction bed (16).

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