Continuous flow reactor and process for synthesizing centralite II

Abstract

The invention relates to the field of chemical reactor technology and flow chemistry, in particular to a continuous flow reactor and process for synthesizing a centralite II. The upper end of the reaction tube assembly is communicated with the raw material mixing assembly, a reactor is arranged outside the reaction tube assembly, the reaction tube assembly is provided with a first reaction branch tube, the first reaction branch tube is sleeved with a second reaction branch tube, and the second reaction branch tube is sleeved with a third reaction branch tube; the lower end part of the first reaction branch pipe is connected with a first discharging assembly, the lower end part of the second reaction branch pipe is connected with a second discharging assembly, and the lower end part of the third reaction branch pipe is connected with a third discharging assembly; and 8 to 12 reaction tube assemblies are arranged in the reactor. According to the invention, the generation efficiency of the centralite II is improved, continuous production is realized, and the unit production efficiency and intrinsic safety are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical reactors, and particularly to a continuous flow reactor and process for the synthesis of stabilizer II. Background Art

[0002] Chemical reactors, by integrating functions such as temperature / pressure control, efficient heat transfer, and safety protection, have become the core carriers of chemical reactions and are widely used in fields such as chemical engineering, pharmaceuticals, and food. Among them, in the field of fine chemical production, compared with traditional batch reactor production systems, continuous flow reactors have significant advantages such as miniaturization or microscale in the unit reaction zone or reaction channel, low unit liquid holdup, enhanced mixing and mass and heat transfer, high reaction rate, easy modular assembly, continuous production, and inherent safety, and have become the development trend in the fields of organic synthesis and flow chemistry.

[0003] Stabilizer II (N,N'-dimethyl-N,N'-diphenylurea) is an important chemical intermediate and stabilizer, and its applications span multiple fields such as military and chemical industries. It is a key component in the production of energetic materials and high-value-added chemicals and is an important organic chemical. Currently, stabilizer II is mainly produced by the reaction of N-methylaniline and phosgene. However, at present, a common batch reactor is used to mix N-methylaniline and phosgene and intermittently produce stabilizer II under reaction conditions, which results in low production efficiency, long residence time of materials in the reaction zone, long reaction and production cycles, intermittent and complex operations, high costs for maintaining safety risks, and relatively low unit production efficiency, which is not conducive to further promotion.

[0004] Therefore, those skilled in the art are committed to developing a continuous flow reactor and process for the synthesis of stabilizer II, which is beneficial to improving the production efficiency of stabilizer II, realizing continuous production, increasing unit production efficiency, and ensuring inherent safety. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a continuous flow reactor and process for the synthesis of stabilizer II, which is beneficial to improving the production efficiency of stabilizer II. The technical solution of the present invention for solving the above technical problem is as follows:[[]] A continuous flow reactor for the synthesis of stabilizer II, comprising a raw material mixing assembly; a reaction tube assembly, the upper end of the reaction tube assembly is communicated with the raw material mixing assembly, a reactor is arranged outside the reaction tube assembly, the reaction tube assembly has a first reaction branch pipe, a second reaction branch pipe is sleeved outside the first reaction branch pipe, and a third reaction branch pipe is sleeved outside the second reaction branch pipe; The lower end of the first reaction branch pipe is connected with a first discharging assembly, the lower end of the second reaction branch pipe is connected with a second discharging assembly, and the lower end of the third reaction branch pipe is connected with a third discharging assembly.

[0006] The beneficial effects of adopting the above scheme are as follows: By setting the multi-layer structure of the first reaction branch pipe, the second reaction branch pipe and the third reaction branch pipe, a larger reaction surface area can be provided for the synthesis of No. II centralizer, so that reactants such as N-methylaniline and phosgene can fully contact and mix in the multi-layer branch pipes, thereby improving the reaction efficiency, increasing the production amount of No. II centralizer, and solving the problem of low production efficiency of the existing mixing reactor.

[0007] On the basis of the above technical scheme, the present invention can also be improved as follows.

[0008] Further, the raw material mixing assembly includes a mixing tank. The two sides of the mixing tank are respectively connected with a phosgene feeding assembly and an N-methylaniline feeding assembly. The upper end of the mixing tank is connected with a liquid caustic feeding assembly. The mixing tank is connected with a discharging tank, and the lower side of the raw material feeding tank is connected with the reaction tube assembly.

[0009] The beneficial effects of adopting the above further scheme are as follows: The raw material mixing assembly is provided with a mixing tank, and the phosgene feeding assembly and the N-methylaniline feeding assembly are respectively connected to the two sides, and the liquid caustic feeding assembly is connected to the upper end, so as to realize the accurate feeding and uniform mixing of phosgene, N-methylaniline and liquid caustic, form a certain raw material fluid countercurrent and mixing strengthening effect, ensure that each raw material fully contacts in a certain proportion, provide good mixing for the efficient progress of the subsequent reaction, and improve the initial reaction effect of the synthesis of No. II centralizer; for example, internal components are arranged near the inlets of the phosgene feeding assembly and the N-methylaniline feeding assembly in the mixing tank, which can further form a certain degree of impinging stream effect and further promote the mixing strengthening effect of the material fluid and the mixing effect.

[0010] Further, the mixing tank and the raw material feeding tank are connected through a feeding pipe, and a control valve is installed on the feeding pipe. The control valve is connected with a control assembly, and the control assembly controls the control valve to be intermittently opened.

[0011] The beneficial effect of adopting the above further scheme is that the raw materials need to be further mixed when entering the mixing box. If a stirring device is installed in the mixing box, the stirring blades will easily stir the phosgene to the top of the mixing box when the stirring device is stirred, and the phosgene cannot be fully mixed with the gaseous and liquid raw materials, thereby affecting the subsequent reaction effect and efficiency. At the same time, due to the small amount of liquid raw material feed, when it directly enters the raw material feed box from the mixing box and then flows to each reaction tube, only the reaction branch pipe in the middle of the raw material feed box continues to have raw materials entering, while less raw material liquid flows to the periphery of the raw material feed box. This unbalanced distribution of raw materials is obviously not conducive to the subsequent reaction process in each reaction tube, resulting in some reaction tubes being unable to fully react due to insufficient raw material supply, thereby affecting the production efficiency and product quality of the entire system.

[0012] In this scheme, the control device intermittently opens the control valve, which allows the various raw materials to have sufficient mixing time in the mixing box, so that the various raw materials can fully contact and blend with each other in the mixing box, laying a good foundation for subsequent reactions, and the raw materials will gather in the mixing box to form a certain amount of raw material reserves; After a certain amount of material is gathered, the control valve is opened to allow the raw materials in the mixing box to flow quickly into the raw material feed box. This fast flow feature allows the raw materials to be quickly and evenly distributed throughout the raw material feed box, ensuring that there is enough raw material everywhere in the raw material feed box to flow downward to each reaction branch pipe, avoiding the problem of insufficient raw materials in some reaction tubes due to uneven distribution of raw materials, greatly improving the raw material utilization rate and reaction efficiency of each reaction tube Moreover, since there is no raw material in each reaction branch pipe before, when a large amount of mixed raw materials suddenly flow from the reaction branch pipe, the gas in the reaction branch pipe will float up in large quantities, causing a large number of bubbles to emerge from the mixed raw materials. The bubbles that emerge further mix the mixed raw materials, just like tiny stirrers, making the mixed raw materials more uniform and sufficient, enhancing the mixing effect, and providing a better quality reactant mixing state for subsequent reactions; At the same time, the unreacted phosgene in each reaction branch pipe is squeezed out and further mixed with the raw materials in the raw material feed box, which can further increase the concentration of phosgene in the mixture, so that the phosgene can more fully participate in the subsequent reaction process, thereby effectively improving the effect and efficiency of the entire phosgene reaction system.

[0013] Further, the first reaction branch pipe, the second reaction branch pipe and the third reaction branch pipe are all hollow pipes, the hollow portion of the first reaction branch pipe is communicated with the interior of the reactor through a first connecting pipe, the hollow portion of the second reaction branch pipe is communicated with the interior of the reactor through a second connecting pipe, and the hollow portion of the third reaction branch pipe is communicated with the interior of the reactor through a third connecting pipe; The inner walls of the first reaction branch pipe, the second reaction branch pipe, and the third reaction branch pipe all have a partition layer. The inner walls of the first reaction branch pipe, the second reaction branch pipe, and the third reaction branch pipe have mounting holes, and rubber balls are fixed in the mounting holes. The partition layer is located between the rubber balls and the mixed raw materials, and the inner cavities of the rubber balls communicate with the hollow parts of the respective reaction branch pipes.

[0014] The beneficial effects of adopting the above further scheme are as follows: The reaction branch pipes communicate with the heating liquid inside the reactor through the corresponding connecting pipes, and the partition layer is made of an elastic material with good thermal conductivity. Appropriate reaction temperatures can be maintained among the first reaction branch pipe, the second reaction branch pipe, and the third reaction branch pipe, avoiding less heat exchange between the inner reaction branch pipes (especially the first reaction branch pipe) and the heating liquid in the reactor and reducing the reaction rate of the mixed raw materials.

[0015] Further, the reactor is filled with heating oil, and the reactor is connected to a booster pump.

[0016] The beneficial effects of adopting the above further scheme are as follows: When the booster pump pressurizes, it not only increases the flow rate of the heating liquid (mainly heating oil) inside the reactor, improves the heat exchange rate of the heating oil itself, but also causes the rubber balls to expand. The expanded rubber balls push the partition layer to protrude outward, causing the falling mixed raw materials to impact the protruding partition layer, increasing the reaction area, breaking large particle raw materials into small particle raw materials, and performing heat exchange with the reaction branch pipes, thereby increasing the reaction rate. In a high-temperature (90°C - 110°C) and alkaline environment, unreacted N-methylaniline will undergo intermolecular condensation to form linear or cross-linked aromatic amine polymers. These polymers are usually viscous or tarry. Due to their large molecular weight and low polarity, they are difficult to dissolve in the aqueous phase system. And if phosgene (COCl2) does not fully participate in the main reaction, it will react with other organic substances (such as aniline substances) to form polychlorinated biphenyls (PCBs) or polychlorinated aromatic hydrocarbons. Such compounds have stable chemical properties and strong hydrophobicity and are likely to deposit on the vessel wall. The deposition of impurities on the surface of the partition layer will reduce the heat conduction efficiency. Therefore, the partition layer is regularly pushed out by the rubber balls, causing the surface tension of the partition layer to continuously change, thereby causing the impurities adhering to the surface of the partition layer to fall off, reducing the deposition of impurities on the surface of the partition layer, and improving the heat exchange efficiency to increase the production rate of the stabilizer.

[0017] Further, 8 to 12 of the reaction tube assemblies are provided inside the reactor.

[0018] The beneficial effects of adopting the above further solution are as follows: setting 8 to 12 reaction tube assemblies can increase the overall reaction area of the reactor, improve the total effective reaction space of the reactor; the liquid holdup in each reaction tube assembly is small, which strengthens the transfer and contact mass transfer of materials and the reaction effect, reduces the residence time of materials, and improves the reaction efficiency; improves the standardization and modularization effects of the reaction tube assemblies; at the same time, it ensures that the reaction materials in each reaction tube can fully contact and react, effectively improving the synthesis efficiency of No. II centralite, increasing the total effective reaction volume and the processing capacity of reaction materials of a single continuous flow reactor, enabling the reactor to process more raw materials per unit time, and enhancing the production capacity of the reactor; at the same time, it further promotes the modularization and standardization of the continuous flow reactor, adapts to the parallel connection of reactors under different production capacities, and facilitates the realization of industrialized large-scale production capacity.

[0019] A process for the synthesis of No. II centralite, applied to the novel reactor for the synthesis of No. II centralite as described above, includes the following steps: S100. Introduce phosgene into the mixing tank through the phosgene feeding assembly, introduce N-methylaniline into the mixing tank through the N-methylaniline feeding assembly, introduce liquid caustic soda into the mixing tank through the liquid caustic soda feeding assembly, and after mixing in the mixing tank, transport it to the raw material feeding tank to form a mixed raw material; S200. Transport the mixed raw material formed in step S100 to the first reaction branch pipe for reaction, and then transport the reaction product material to the first discharge assembly; Transport the mixed raw material formed in step S100 to the second reaction branch pipe for reaction, and then transport the reaction product material to the second discharge assembly; Transport the mixed raw material formed in step S200 to the third reaction branch pipe for reaction, and then transport the reaction product material to the third discharge assembly.

[0020] S300. Subject the compounds in the first discharge assembly, the second discharge assembly, and the third discharge assembly in step S200 to hot washing, dehydration, and distillation to prepare No. II centralite.

[0021] The beneficial effects of adopting the above further solution are as follows: after introducing each raw material into the mixing tank through the phosgene feeding assembly, the N-methylaniline feeding assembly, and the liquid caustic soda feeding assembly for mixing, and then transporting it to the raw material feeding tank to form a mixed raw material, it ensures that each raw material reaches a fully uniform mixing state before entering the reaction tube assembly, provides a good raw material basis for subsequent reactions, and improves the initial reaction efficiency; The mixed raw materials are respectively transported to the first reaction branch pipe, the second reaction branch pipe and the third reaction branch pipe, and the synthesized products are collected in their respective corresponding discharge components, reducing the liquid holdup in each branch pipe, enhancing the transfer and reaction efficiency, realizing the parallel reaction mode of multiple reaction branch pipes, greatly increasing the total contact area and reaction rate of the reaction, reducing the residence time required for the material reaction to be completed, enabling the synthesis of stabilizer No. II to be completed in a relatively short time, and improving the production efficiency.

[0022] Further, in step S100, the liquid caustic soda is an aqueous sodium hydroxide solution with a mass fraction of 16% - 20%; In step S200, the reaction zone temperature in the first reaction branch pipe, the second reaction branch pipe and the third reaction branch pipe is 90°C - 110°C.

[0023] The beneficial effect of adopting the above further scheme is that the liquid caustic soda within the appropriate concentration range can not only ensure that the reaction system has an appropriate alkaline strength to promote the formation of stabilizer No. II, but also avoid problems such as increased side reactions and equipment corrosion that may be caused by too high a concentration of liquid caustic soda; At this temperature, the reaction rate is relatively fast, and at the same time, the reaction selectivity is relatively high, which can effectively reduce the formation of by-products, improve the purity and yield of stabilizer No. II, and ensure the efficient progress of the reaction process.

[0024] Further, after step S300, it further includes: S400. The booster pump intermittently pressurizes the reactor to make the rubber ball expand to push the partition layer.

[0025] The beneficial effect of adopting the above further scheme is that the rubber ball expands to push the partition layer, causing the protrusions and tensions on the surface of the partition layer to change. This not only facilitates the falling and impact of the mixed raw materials to break into small particles, but also reduces the attachment of deposited impurities on the surface of the partition layer. Description of the Drawings

[0026] Figure 1 It is a plan sectional view of the continuous flow reactor for the synthesis of stabilizer No. II of the present invention; Figure 2 It is a cross-sectional view of the reaction tube assembly in the present invention.

[0027] In the drawings, the list of components represented by each reference numeral is as follows: 1. Raw material mixing assembly; 2. Reaction tube assembly; 3. Reactor; 4. First reaction branch tube; 5. Second reaction branch tube; 6. Third reaction branch tube; 7. First discharge assembly; 8. Second discharge assembly; 9. Third discharge assembly; 10. Mixing tank; 11. Phosgene feeding assembly; 12. N-methylaniline feeding assembly; 13. Liquid caustic soda feeding assembly; 14. Raw material feeding tank; 15. Feeding pipe; 16. Control valve; 17. First connecting pipe; 18. Second connecting pipe; 19. Third connecting pipe; 20. Rubber ball; 21. Interlayer. Detailed implementation mode

[0028] The principles and features of the present invention will be described below in conjunction with the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0029] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "length", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "inner", "outer", "peripheral side", "circumferential direction", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention.

[0030] In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0031] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Such as Figure 1 、 Figure 2As shown in the figure, a continuous flow reactor for the synthesis of stabilizer II includes a raw material mixing component 1 and a reaction tube component 2 that constitutes the core area of the reactor. The upper end of the reaction tube component 2 is closely connected to the raw material mixing component 1, and the outside of the reaction tube component 2 is wrapped by the reactor 3. In a specific implementation case, 8 to 12 reaction tube components 2 are arranged inside the reactor 3 to optimize the reaction scale and efficiency. The reaction tube component 2 itself has a unique structure, which includes a first reaction branch tube 4. The outside of the first reaction branch tube 4 is sequentially sleeved with a second reaction branch tube 5 and a third reaction branch tube 6 to form a multi-layer nested reaction channel. At the same time, the lower end of the first reaction branch tube 4 is connected to a first discharge component 7, the lower end of the second reaction branch tube 5 is correspondingly connected to a second discharge component 8, and the lower end of the third reaction branch tube 6 is connected to a third discharge component 9. Each discharge component is responsible for collecting the synthesized substances in the corresponding reaction branch tube.

[0033] The raw material mixing component 1 includes a mixing tank 10. On both sides of the mixing tank 10, a phosgene feeding component 11 and an N-methylaniline feeding component 12 are precisely connected respectively to ensure that these two important raw materials can be accurately and stably input into the mixing tank 10. There is also a liquid caustic feeding component 13 at the upper end of the mixing tank 10. The liquid caustic is added to the mixing tank 10 through this component and is fully mixed with other raw materials. The mixing tank 10 is connected to a raw material feeding tank 14. The raw material feeding tank 14 is located below the mixing tank 10. After the mixed raw materials complete the preliminary homogenization mixing process in the mixing tank 10, they will be transported into the raw material feeding tank 14, and finally form uniform mixed raw materials. The lower side of the raw material feeding tank 14 is connected to the reaction tube component 2 to achieve a smooth transition and transportation of the mixed raw materials to the reaction tube component 2.

[0034] In other embodiments, the mixing tank 10 and the raw material feeding tank 14 are connected through a feeding pipe 15, and a control valve 16 is installed on the feeding pipe 15. The control valve 16 is connected to a control component (not shown in the figure), and the control component controls the control valve 16 to open intermittently.

[0035] The first reaction branch tube 4, the second reaction branch tube 5, and the third reaction branch tube 6 are all hollow tubes. The hollow part of the first reaction branch tube 4 is communicated with the inside of the reactor 3 through multiple first connecting pipes 17. The hollow part of the second reaction branch tube 5 is communicated with the inside of the reactor 3 through multiple second connecting pipes 18. The hollow part of the third reaction branch tube 6 is communicated with the inside of the reactor 3 through multiple third connecting pipes 19. Heating oil is filled in the reactor 3, and the reactor 3 is connected to a booster pump, so that the first reaction branch tube 4, the second reaction branch tube 5, and the third reaction branch tube 6 are all maintained at a suitable reaction temperature.

[0036] The inner walls of the first reaction branch pipe 4, the second reaction branch pipe 5 and the third reaction branch pipe 6 are all provided with a partition layer 21, and the partition layer 21 is made of elastic high thermal conductive material. The inner walls of the first reaction branch pipe 4, the second reaction branch pipe 5 and the third reaction branch pipe 6 are provided with mounting holes, and rubber balls 20 are fixed in the mounting holes. The partition layer 21 is located between the rubber ball 20 and the mixed raw materials, and the inner cavity of the rubber ball 20 is respectively communicated with the hollow parts of each reaction branch pipe, so that the rubber ball 20 expands under the action of the heating oil to push the partition layer 21.

[0037] Based on the above-mentioned continuous flow reactor for the synthesis of the No. Ⅱ intermediate fixer, the present invention also proposes a matching process flow for the synthesis of the No. Ⅱ intermediate fixer. The process comprises the following steps: Step S100: Phosgene is introduced into the mixing box 10 by means of the phosgene feed assembly 11, and at the same time, N-methylaniline is introduced into the mixing box 10 by means of the N-methylaniline feed assembly 12. In addition, liquid caustic soda is introduced into the mixing box 10 by means of the liquid caustic soda feed assembly 13, wherein the liquid caustic soda is selected from a sodium hydroxide aqueous solution having a sodium hydroxide mass fraction of 16% to 20%. In the mixing box 10, the two raw materials of phosgene and N-methylaniline and the liquid caustic soda catalyst are fully mixed to form a uniform mixture, which is then transported to the raw material feed box 14 to form a mixed raw material containing a catalyst that can be used for subsequent reactions.

[0038] Step S200: The mixed raw material formed in the mixing box 10 and outputted through the raw material feed box 14 in step S100 is transported to the first reaction branch pipe 4, passes through the reaction zone in the first reaction branch pipe 4 and reacts under the condition of a set temperature range of 90° C. to 110° C., and then is transported to the first discharge assembly 7 for collection; Similarly, the mixed raw material formed in step S100 is transported to the second reaction branch pipe 5, and reacts in the reaction zone of the second reaction branch pipe 5 at a set temperature range of 90°C to 110°C, and then transported to the second discharge assembly 8. In addition, the mixed raw material in step S100 is further transported to the third reaction branch pipe 6, and reacts in the reaction zone of the third reaction branch pipe 6 at a set temperature range of 90°C to 110°C, and then the reacted composite is transported to the third discharge assembly 9 for collection.

[0039] Step S300: The compositions collected in the first discharge assembly 7, the second discharge assembly 8, and the third discharge assembly 9 in Step S200 are subjected to subsequent processing. Specifically, these compositions are successively subjected to a series of refining and separation operations such as hot washing, dehydration, and distillation, and finally the target product, stabilizer II, is successfully prepared. The entire process flow is closely centered around the structural characteristics of the continuous flow reactor, giving full play to its advantages of multi-branch pipe stratified reaction, segmented discharge, precise temperature control, short residence time of materials in reaction, enhanced transfer and reaction rate, continuous operation, etc., realizing the high-efficiency continuous and high-quality synthesis of stabilizer II.

[0040] Step S400: The booster pump intermittently pressurizes the reactor 3 to cause the rubber ball 20 to expand so as to push the partition layer 21. When the rubber ball 20 expands to push the partition layer 21, the protrusions and tensions on the surface of the partition layer 21 change, which not only facilitates the falling and impact of the mixed raw materials to be broken into small particles, but also reduces the attachment of deposited impurities to the surface of the partition layer 21.

[0041] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0042] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous flow reactor for the synthesis of a No. Ⅱ intermediate, characterized in that: include Raw material mixing assembly (1); A reaction tube assembly (2), wherein the upper end of the reaction tube assembly (2) is in communication with the raw material mixing assembly (1), a reactor (3) is arranged outside the reaction tube assembly (2), the reaction tube assembly (2) comprises a first reaction branch pipe (4), a second reaction branch pipe (5) is arranged outside the first reaction branch pipe (4), and a third reaction branch pipe (6) is arranged outside the second reaction branch pipe (5); The lower end of the first reaction branch pipe (4) is connected to a first discharge assembly (7), the lower end of the second reaction branch pipe (5) is connected to a second discharge assembly (8), and the lower end of the third reaction branch pipe (6) is connected to a third discharge assembly (9).

2. The continuous flow reactor for synthesis of No. II intermediate according to claim 1, characterized in that: The raw material mixing assembly (1) comprises a mixing box (10), the two sides of the mixing box (10) are respectively connected to a phosgene feed assembly (11) and an N-methylaniline feed assembly (12), the upper end of the mixing box (10) is connected to a liquid caustic soda feed assembly (13), the mixing box (10) is connected to a raw material feed box (14), and the lower side of the raw material feed box (14) is connected to the reaction tube assembly (2).

3. The continuous flow reactor for synthesizing the No. Ⅱ intermediate according to claim 2, characterized in that: The mixing box (10) is connected to the raw material feed box (14) via a feed pipe (15), and the feed pipe (15) is provided with a control valve (16), the control valve (16) is connected to a control component, and the control component controls the control valve (16) to be opened intermittently.

4. The continuous flow reactor for synthesis of No. II intermediate according to claim 1, characterized in that: The first reaction branch pipe (4), the second reaction branch pipe (5) and the third reaction branch pipe (6) are all hollow pipes; the hollow portion of the first reaction branch pipe (4) is communicated with the interior of the reactor (3) via a first connecting pipe (17); the hollow portion of the second reaction branch pipe (5) is communicated with the interior of the reactor (3) via a second connecting pipe (18); and the hollow portion of the third reaction branch pipe (6) is communicated with the interior of the reactor (3) via a third connecting pipe (19); The inner walls of the first reaction branch tube (4), the second reaction branch tube (5) and the third reaction branch tube (6) are each provided with a partition layer (21); the inner walls of the first reaction branch tube (4), the second reaction branch tube (5) and the third reaction branch tube (6) are provided with mounting holes; a rubber ball (20) is fixed in the mounting hole; the partition layer (21) is located between the rubber ball (20) and the mixed raw material; and the inner cavity of the rubber ball (20) is respectively communicated with the hollow portion of each reaction branch tube.

5. The continuous flow reactor for synthesis of No. II intermediate according to claim 1, characterized in that: The reactor (3) is filled with heating oil, and the reactor (3) is connected to a booster pump.

6. The continuous flow reactor for synthesis of No. II intermediate according to claim 1, characterized in that: Eight to twelve reaction tube assemblies (2) are arranged in the reactor (3).

7. A process for synthesizing a No. Ⅱ intermediate fixer, applied to the continuous flow reactor for synthesizing a No. Ⅱ intermediate fixer as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: S100. Phosgene is introduced into the mixing box (10) through the phosgene feed assembly (11), phosgene and N-methylaniline are introduced into the mixing box (10) through the N-methylaniline feed assembly (12), and liquid caustic soda is introduced into the mixing box (10) through the liquid caustic soda feed assembly (13). After the mixture is mixed in the mixing box (10), the mixture is transported to the raw material feed box (14) to form a mixed raw material; S200. The mixed raw material formed in step S100 is transported to the first reaction branch pipe (4) for reaction, and the product material after the reaction is then transported to the first discharging assembly (7); The mixed raw material formed in step S100 is transported to the second reaction branch pipe (5) for reaction, and the product material after the reaction is transported to the second discharge assembly (8); The mixed raw material formed in step S200 is transported to the third reaction branch pipe (6) for reaction, and the product material after the reaction is transported to the third discharge assembly (9); S300. The composition in the first discharging component (7), the composition in the second discharging component (8) and the composition in the third discharging component (9) in step S200 are subjected to heat washing, dehydration and distillation to prepare a No. II neutralizing agent.

8. The process for synthesizing the No. Ⅱ neutralizing agent according to claim 7, characterized in that: In step S100, the liquid alkali is a sodium hydroxide aqueous solution with a mass fraction of 16% to 20%; In step S200, the temperature of the reaction zones in the first reaction branch pipe (4), the second reaction branch pipe (5) and the third reaction branch pipe (6) is 90°C to 110°C.

9. The process for synthesizing the No. Ⅱ neutralizing agent according to claim 7, characterized in that: After step S300, the method further includes: S400. The booster pump intermittently increases the pressure in the reactor (3) so that the rubber ball (20) expands to push the partition (21).

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