Organic amine phosgenation reactor and process

Abstract

The present disclosure relates to an organic amine phosgenation reactor and process. The reactor mainly comprises: a feed atomizing nozzle 1, a gas outlet 2, a first and a second wall flow annular tube 3, a cold phosgenation feed pipe 4, a secondary phosgenation feed pipe 5, a first and a second cooling nozzle 6, an overflow pipe 7, a flushing pipe 8, a bottom outlet 9, a first and a second gate valve 10 and a transfer hopper 11. The reactor has no internal components of a complex structure and is easy to manufacture; it can meet the requirements of both high and low pressure phosgenation reactions and is easy to control; it effectively solves the solid problem of the phosgenation reaction, and is safe and reliable for long-term continuous operation, with significant economic benefits.

Description

Technical Field

[0001] The present disclosure relates to the technical field of preparing related downstream products through phosgenation reaction of organic amines, and in particular to an organic amine phosgenation reactor and process. Background Art

[0002] Phosgenation reactors are mainly used in the production and synthesis of isocyanates. Currently, the phosgenation production technologies used in industry mainly include gas phase phosgenation and liquid phase phosgenation.

[0003] Gas-phase phosgenation is a method of directly mixing some gasifiable amine compounds with phosgene for gas-phase reaction after gasification at 200-600°C. This method was originally developed by Bayer Company of Germany, with a yield of more than 98%. It is suitable for the phosgenation of low-boiling-point and highly active amine compounds, and has become the mainstream production technology for aliphatic isocyanates. However, gas-phase phosgenation has very high requirements for the reactor: the reactor inlet is a high-speed static mixing device for the strong mixing of amine and phosgene; the narrow reaction channel has a gas velocity of up to tens of meters per second, little backmixing and a transit time of less than 0.5s; and the reaction requires rapid heat transfer. Therefore, only a few companies have mastered this technology so far.

[0004] Liquid phase phosgenation usually dissolves organic amine and phosgene in solvents respectively, and then mixes them at 60-145°C for reaction. It mainly includes cold and hot phosgenation, one-step high temperature phosgenation, low pressure phosgenation and high pressure phosgenation. This method is mainly used in the production of aromatic isocyanates. Representative continuous processes include kettle continuous process, tower continuous process and circulating continuous process. Liquid phase phosgenation is mainly used for production in China.

[0005] During the phosgenation process, the HCl produced by the phosgenation of organic amines will further react with amines to form amine hydrochlorides. This is a very fast process. Due to the low solubility of salts, a considerable amount of solids will precipitate from the solvent. At the same time, urea produced by the side reaction of formyl chloride and amine hydrochlorides is also one of the sources of solids in this process. A large number of practices have proved that even the gas phase phosgenation method cannot completely avoid the generation of solids. The generation of solids not only affects the phosgenation yield, but its accumulation directly leads to various abnormal conditions such as increased system pressure and channel blockage. In severe cases, it is forced to stop the system for maintenance, which is extremely unfavorable for the use and operation of toxic and harmful phosgene. Summary of the invention

[0006] The present invention provides a novel reactor for phosgenation of organic amines, and also provides a process method for phosgenation of organic amines. The method improves the phosgenation rate of organic amines and suppresses side reactions as much as possible by controlling the progress of the phosgenation reaction in stages, and also takes corresponding measures for the generated solids, thereby solving the blockage problem.

[0007] The technical solution of the present disclosure is as follows:

[0008] An organic amine phosgenation reactor comprises, from top to bottom:

[0009] A feed atomizing nozzle, which is arranged at the center of the top of the reactor and is used for feeding the organic amine solution;

[0010] A gas outlet, which is located at the top edge of the reactor and is used to discharge excess phosgene and produced HCl;

[0011] The first and second wall flow loop pipes are arranged on the reactor wall, wherein the first wall flow loop pipe is located at the upper part of the reactor and the second wall flow loop pipe is located at the middle part of the reactor, and are used to spray solvent to flush the solids attached to the reactor wall so that the solids become slurry and flow down the wall;

[0012] A cold light gas feed pipe, which is located at the upper part of the reactor, and the outlet is located on the central axis of the reactor and is bent downward, and is used to introduce cold light gas into the reactor;

[0013] The first cooling nozzle is located 100-400 mm below the cold light gas feed pipe and is a group of nozzles arranged on the reactor wall, which is used to spray low-temperature atomized solvent into the reactor to control the reaction temperature of this section. This group of nozzles is located at the same height of the reactor and is evenly distributed along the radial direction of the reactor. The first cooling nozzle includes at least 2 nozzles, each nozzle is obliquely downwardly pointed to the center of the reactor, and the angle between the nozzle and the reactor wall is 20-80°;

[0014] A secondary phosgene feed pipe, which is located in the middle of the reactor, and has an outlet located on the central axis of the reactor and bent downward, and is used to introduce phosgene into the reactor;

[0015] The second cooling nozzle is located 100-400 mm below the secondary phosgene feed pipe and is a group of nozzles arranged on the reactor wall, and is used to spray low-temperature atomized solvent into the reactor to control the reaction temperature of this section. This group of nozzles is located at the same height of the reactor and is evenly distributed along the radial direction of the reactor. The second cooling nozzle includes at least 2 nozzles, each nozzle is obliquely downwardly pointed to the center of the reactor, and the angle between the nozzle and the reactor wall is 20-80°;

[0016] Flushing pipes, which are located at the lower part of the reactor and are evenly distributed along the reactor wall at the same height, with a number of 2-12, and are used to flush the solids deposited at the bottom of the reactor;

[0017] An overflow pipe, located at the bottom of the reactor, is used to discharge the clear liquid from the bottom of the reactor;

[0018] Bottom outlet:

[0019] first and second gate valves; and

[0020] Transfer hopper;

[0021] The first and second gate valves, the transfer hopper and the bottom outlet together constitute a slurry discharge structure, wherein the upper inlet of the transfer hopper is connected to the bottom outlet through the first gate valve, and the lower outlet of the transfer hopper is discharged through the second gate valve.

[0022] The feed atomizing nozzle can be a single nozzle, or a combination of multiple nozzles or a multi-hole nozzle, which is mainly determined by the size of the reactor and the processing amount of the organic amine. The spray angle of the feed atomizing nozzle is preferably 40-120°, more preferably 60-100°. The feed atomizing nozzle is configured so that the shape of the sprayed liquid mist is a solid cone and evenly distributed, and the coverage area of ​​the sprayed liquid mist is less than and close to the reactor diameter (for example, more than 90% of the reactor diameter, preferably more than 95%). The droplet size produced by the feed atomizing nozzle is 10-400μm, preferably 10-200μm, and more preferably 20-100μm.

[0023] The outlets of the cold phosgene feed pipe and the secondary phosgene feed pipe are bent downward, preferably at 90°, to prevent solids from falling in.

[0024] The angle between the first and second cooling nozzles and the vessel wall is preferably 30-60°. The first cooling nozzle and the second cooling nozzle each independently include 4-8 nozzles.

[0025] The number of the flushing tubes is preferably 4-6.

[0026] Preferably, the first and second wall flow annular tubes are coaxially installed with the reactor. The outer diameter of the first and second wall flow annular tubes is 0.8-0.98 times the inner diameter of the reactor, and the inner diameter is not greater than 75% of the inner diameter of the reactor. In addition, the outer sides of the first and second wall flow annular tubes are evenly arranged with holes slightly inclined downward or a plurality of downward spraying nozzles are arranged, so that the sprayed solvent flushes the inner wall of the reactor in a jet shape. Other structures with the same function can also be selected to replace the wall flow annular tube.

[0027] Preferably, the flushing pipe can be a jet-type flushing pipe, and the jet of solvent sprayed out can play the role of stirring and disturbing the solids, thereby facilitating the flushing of the solids deposited at the bottom of the kettle and ensuring smooth discharge of the material from the bottom outlet.

[0028] The phosgenation reaction process using the reactor disclosed herein includes:

[0029] (1) preparing an organic amine solution with a mass concentration of 10-70%, preferably 20-50%, controlling the feed temperature to 0-65°C after heat exchange, spraying it downward into the reactor from a feed atomizing nozzle, with a spray angle of 20-160°, preferably 40-120°, more preferably 60-100°, and the sprayed liquid mist is in the shape of a solid cone, evenly distributed in the cross section of the reactor, and the droplet size is 10-400 μm, preferably 10-200 μm, more preferably 20-100 μm;

[0030] (2) introducing phosgene from a cold phosgene feed pipe, wherein the molar ratio of phosgene to organic amine is 2-15, preferably 3-6, and the phosgene feed temperature is controlled at -10-65°C, and the phosgene and organic amine solution mist are in reverse contact and react to release heat;

[0031] (3) by controlling the flow rate, concentration and inlet temperature of the organic amine solution, and the feed temperature and flow rate of the cold phosgene, the reaction temperature of this stage is effectively controlled not to exceed 180° C., preferably 80-150° C. and not to exceed the boiling point of formyl chloride;

[0032] (4) After the first stage of cold light gasification, the droplets contain formyl chloride, amine hydrochloride and unreacted organic amine, and the droplets fall from top to bottom into the second stage of the reactor for further reaction;

[0033] (5) introducing phosgene from a secondary phosgene feed pipe, wherein the molar ratio of phosgene to organic amine is 2-10, preferably 3-6, and the phosgene feed temperature is controlled at 20-160° C. The phosgene and the droplets are in reverse contact at high temperature and continue to undergo phosgenation reaction in the second stage of the reactor to generate formyl chloride, accompanied by a decomposition reaction of the formyl chloride;

[0034] (6) controlling the phosgene feed temperature and flow rate of the secondary phosgene feed pipe, as well as the amount and temperature of the solvent sprayed by the first cooling nozzle under the cold phosgene feed pipe, to ensure that the second stage reaction temperature does not exceed the boiling point of formyl chloride;

[0035] (7) intermittently or continuously opening the first and second wall flow loops, spraying solvent to wash along the wall surface to dilute the viscous slurry accumulated on the wall surface and finally accumulating it into the bottom of the reactor;

[0036] (8) Open the flushing pipe, adjust the solvent feed amount and feed temperature according to the solid content and material temperature of the bottom material, and maintain the feed temperature at 20-120° C. so that the solvent and the bottom material do not exceed the boiling point of formyl chloride after mixing;

[0037] (9) The reacted materials are precipitated and separated at the bottom of the reactor, and the supernatant continues to flow out from the overflow port at the bottom of the reactor;

[0038] (10) After the solid solution is enriched at the bottom of the reactor, a discharging operation is performed;

[0039] (11) Excess phosgene and produced HCl flow out from the gas outlet at the top of the reactor.

[0040] In particular, when the reactor comprises the first and second gate valves as described above; and a transfer hopper, the discharge operation in the above process comprises the following steps:

[0041] a) First, open the nitrogen filling valve of the transfer hopper, and start to introduce nitrogen into the hopper according to the pressure of the reactor until the pressure in the hopper is balanced with that in the reactor, and then stop introducing nitrogen;

[0042] b) closing the overflow port, opening the first gate valve below the bottom outlet, and unloading the solid-containing liquid into the transfer hopper;

[0043] c) increasing the solvent flow rate of the flushing pipe, preferably using a jet nozzle to flush the pipe, flushing the residual slurry at the bottom of the reactor, and then closing the first gate valve;

[0044] d) Adjust the pressure of the transfer hopper to meet the downstream reaction requirements; then open the second gate valve under the transfer hopper to output the slurry.

[0045] Beneficial Effects

[0046] The present invention discloses a novel reactor and its preparation process to solve the safety problems that the associated hydrochloride solids in the phosgenation reaction process easily lead to increased system pressure and blocked pipeline valves. The reactor has no internal components with complex structures and is easy to manufacture; it can meet the requirements of both high-pressure and low-pressure phosgenation reactions and is easy to control; it effectively solves the solid problem of the phosgenation reaction, and is safe and reliable for long-term continuous operation, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic diagram of a continuous phosgenation reactor according to the present disclosure.

[0048] Figure 2 is a schematic diagram of one embodiment of a wall flow loop suitable for use in the present disclosure.

[0049] Reference numerals

[0050] 1-feed atomizing nozzle, 2-gas outlet, 3-first and second wall flow loop pipes, 4-cold phosgene feed pipe, 5-secondary phosgene feed pipe, 6-first and second cooling nozzles, 7-overflow pipe, 8-flushing pipe, 9-bottom outlet, 10-gate valve, 11-transfer hopper DETAILED DESCRIPTION

[0051] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings, but are not intended to limit the present disclosure.

[0052] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the following description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope and spirit of the present disclosure may be conceived by those skilled in the art without creative effort. These modifications also fall within the scope of protection of the appended claims.

[0053] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0054] These and other characteristics of the present disclosure will become apparent from the following description of a preferred form of embodiment given as a non-limiting example, with reference to the attached drawings.

[0055] It should also be understood that, although the present disclosure has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the present disclosure that have the features described in the claims and are therefore within the scope of protection defined thereby.

[0056] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0057] This specification may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0058] According to one embodiment of the present disclosure, an organic amine phosgenation reactor is provided, and a preparation process method thereof is also provided.

[0059] Figure 1 Schematic diagram of a continuous phosgenation reactor according to the present disclosure. Figure 1 The reactor mainly includes: a feed atomizing nozzle 1, a gas outlet 2, a first and a second wall flow loop tube 3, a cold phosgene feed pipe 4, a secondary phosgene feed pipe 5, a first and a second cooling nozzle 6, an overflow pipe 7, a flushing pipe 8, a bottom outlet 9, a first and a second gate valve 10 and a transfer hopper 11.

[0060] The feed atomizing nozzle 1 is arranged at the center of the top of the reactor and is mainly used for feeding the organic amine solution. It can be a single nozzle, a combination of multiple nozzles or a multi-hole nozzle, which is mainly determined by the size of the reactor and the processing amount of the organic amine.

[0061] The spray angle of the feed atomizing nozzle 1 can be 20-160°, preferably 40-120°, and more preferably 60-100°. If the angle is too small, the space utilization rate is too low, and the dense material is not conducive to heat dissipation. If the angle is too large, it will be directly sprayed onto the wall. Here, the spray angle is a technical indicator of the nozzle product, which refers to the cone angle when the sprayed material is conical.

[0062] The sprayed liquid mist is in the shape of a solid cone and is evenly distributed. The coverage area of ​​the sprayed liquid mist is smaller than and close to the diameter of the reactor, which may be more than 90% of the reactor diameter, preferably more than 95%.

[0063] The droplet size produced by the feed atomizing nozzle 1 is 10-400 μm, preferably 10-200 μm, more preferably 20-100 μm.

[0064] The cold phosgene feed pipe 4 and the secondary phosgene feed pipe 5 are located at the upper and middle parts of the reactor respectively, and are mainly used to introduce phosgene into the reactor. The outlet of the feed pipe is located on the central axis of the reactor and is bent downward, preferably at 90°, to prevent solids from falling in.

[0065] The first and second cooling nozzles 6 are groups of nozzles arranged on the reactor wall. The group of nozzles is located at the same height of the reactor and is evenly distributed along the radial direction of the reactor. They are mainly used to spray low-temperature atomized solvent into the reactor to control the reaction temperature of this section.

[0066] Each of the first and second cooling nozzles 6 points obliquely downward toward the center of the reactor, and the angle between the nozzle and the reactor wall is 20-80°, preferably 30-60°.

[0067] The first and second cooling nozzles 6 each independently include at least 2 nozzles, preferably 4-8 nozzles. Within the above range, a good cooling effect can be achieved. If the number of nozzles is less than 2, the cooling effect may be insufficient. There is no particular upper limit on the number of nozzles, but too many nozzles will be uneconomical.

[0068] The first and second cooling nozzles 6 are respectively arranged at a distance of 100-400 mm below the cold phosgene feed pipe 4 and the secondary phosgene feed pipe 5 to ensure that the introduced phosgene is not affected by the injected solvent. If the distance is too close, for example, less than 100 mm, the flow fields will affect each other, that is, the flow fields of the introduced phosgene and the injected solvent will disturb each other, and if the distance is too far, for example, greater than 400 mm, the corresponding cooling effect will not be achieved.

[0069] The first and second wall flow loops 3 are mainly used to spray solvent to flush the solids attached to the reactor wall, so that the solids become slurry and flow down the wall. A set of wall flow loops is respectively arranged at the upper part and the middle part of the reactor.

[0070] Preferably, the wall flow loop 3 is installed coaxially with the reactor.

[0071] In addition, the outer diameter of the wall flow annular tube 3 can be 0.8-0.98% of the inner diameter of the reactor. Here, the outer diameter of the wall flow annular tube 3 refers to the outer diameter of the wall flow annular tube. Within the above range, the wall flow annular tube 3 can be as close to the inner wall of the reactor as possible to facilitate flushing without affecting the flow and reaction of the main body inside the reactor.

[0072] In addition, the inner diameter of the wall flow loop 3 is not greater than 75% of the inner diameter of the reactor. If the inner diameter is greater than 0.75% of the inner diameter of the reactor, the wall flow loop 3 will affect the main flow of the material in the reactor.

[0073] In addition, the wall flow annular tube 3 is preferably provided with holes evenly arranged at a slight downward angle on the outside or multiple nozzles are evenly arranged on the outer circumference of the annular tube, so that the sprayed solvent flushes the inner wall of the reactor in a jet-like manner. The arrangement of the holes or nozzles and the setting of the inner and outer diameters of the wall flow annular tube 3 can ensure that sufficient and powerful flushing occurs at a certain flow rate, so that solids are not locally accumulated on the inner wall of the reactor.

[0074] Figure 2 is a schematic diagram of one embodiment of a wall flow loop suitable for use in the present disclosure.

[0075] The wall flow annular tube 3 may also be replaced by other structures having the same function.

[0076] The overflow pipe 7, flushing pipe 8 and bottom outlet 9 are all located at the bottom of the reactor.

[0077] The overflow pipe 7 is used to guide the clear liquid at the bottom of the kettle, which is mainly formyl chloride solution.

[0078] The flushing pipe 8 is used to flush the solids deposited at the bottom of the reactor to ensure smooth discharge of the bottom outlet. The flushing pipes 8 are preferably evenly distributed along the reactor wall at the same height, with a number of 2-12, preferably 4-6.

[0079] The bottom outlet 9, the first and second gate valves 10 and the transfer hopper 11 together constitute a slurry discharge structure. The slurry discharge is completed by high and low pressure switching of the first and second gate valves 10 and the transfer hopper 11, while ensuring the sealing and safety of the reactor system.

[0080] Preferably, the flushing pipe 8 can be a jet-type flushing pipe, and the jet of solvent sprayed out can play the role of stirring and disturbing the solids, thereby facilitating the flushing of the solids deposited at the bottom of the kettle and ensuring smooth discharge of the bottom outlet 9.

[0081] As required, the transfer hopper may be provided with an air inlet, an air outlet and corresponding inflation valves and deflation valves. In addition, as required, the reactor of the present invention may be provided with other valves, devices, etc.

[0082] Reference below Figure 1 The specific operation mode of the preparation process according to the present disclosure is specifically described:

[0083] 1) The prepared organic amine solution has a mass concentration of 10-70%, preferably 20-50%, and the feed temperature after heat exchange is 0-65°C, and is sprayed downward into the reactor from the feed atomizing nozzle 1, and the spray angle is 20-160°, preferably 40-120°, and more preferably 60-100°. The sprayed liquid mist is in the shape of a solid cone and is evenly distributed in the cross section of the reactor. The droplet size is 10-400μm, preferably 10-200μm, and more preferably 20-100μm;

[0084] 2) Phosgene is introduced from the cold phosgene feed pipe 4, the molar ratio of phosgene to organic amine is 2-15, preferably 3-6, and the phosgene inlet temperature is -10-65°C. Phosgene in the reactor reacts with the organic amine solution mist in step 1) in reverse contact to generate formyl chloride and amine hydrochloride, while releasing heat. This part is called the cold phosgene gasification reaction section.

[0085] 3) by controlling the inlet flow rate, concentration and temperature of the organic amine solution in step 1), and the feed temperature and flow rate of cold phosgene in step 2), the reaction temperature in this stage is effectively controlled not to exceed 180° C., preferably 80-150° C. and not to exceed the boiling point of formyl chloride, so as to avoid the formation of urea as a byproduct;

[0086] 4) After the first stage of cold light gasification, the droplets mainly contain formyl chloride, amine hydrochloride and unreacted organic amine, and the droplets fall from top to bottom into the second stage of the reactor for further reaction;

[0087] 5) Phosgene is introduced from the secondary phosgene feed pipe 5, the molar ratio of phosgene to organic amine is 2-10, preferably 3-6, the phosgene feed temperature is controlled at 20-160° C. Phosgene and the droplets are in reverse contact at high temperature to continue phosgenation reaction. This section is called high-temperature phosgenation reaction section, and the main reaction is phosgenation of amine hydrochloride to form formyl chloride;

[0088] 6) adjusting the amount of solvent sprayed by the first cooling nozzle and its temperature, and controlling the phosgene feed temperature and flow rate (also referred to as feed amount) of the secondary phosgene feed pipe 5, to ensure that the reaction temperature of the high-temperature phosgenation stage does not exceed the boiling point of formyl chloride, thereby inhibiting the decomposition of formyl chloride, because the decomposed formyl chloride and the unreacted organic amine will generate urea as a byproduct;

[0089] 7) In step 1), a large number of droplets sprayed from the top of the reactor will inevitably adhere to the inner wall of the reactor during the falling process; since the droplets contain solids in the contact reaction with phosgene, they will eventually accumulate on the wall in the form of viscous slurry and will not flow down easily; according to the actual situation, the first and second wall flow loops 3 are opened intermittently or continuously, and the solvent is sprayed to flush along the wall to dilute the viscous slurry accumulated on the wall, and finally flow into the bottom of the reactor;

[0090] 8) The droplets in step 5) and the wall flow in step 7) are finally merged into the bottom of the reactor. The amount of solvent added to the flushing pipe 8 and the solvent temperature are adjusted according to the solid content and temperature of the bottom material. The solvent temperature is maintained at 20-120° C., and the bottom material finally obtained does not exceed the boiling point of formyl chloride;

[0091] 9) The bottom material obtained in step 8) is precipitated and separated at the bottom of the reactor, and the supernatant continuously flows out from the overflow pipe 7 and enters the downstream to continue the high-temperature decomposition of the formyl chloride;

[0092] 10) After the solid solution in step 8) is enriched at the bottom of the reactor, a discharging operation is performed;

[0093] 11) Excess phosgene and produced HCl flow out from the gas outlet 2 at the top of the reactor.

[0094] In particular, when the reactor includes the first and second gate valves 10 and the transfer hopper 11, the discharge in the above process includes the following steps:

[0095] a) First, open the nitrogen filling valve of the transfer hopper 11, and start to introduce nitrogen into the hopper 11 according to the pressure of the reactor until the pressure in the hopper is balanced with that in the reactor, and then stop introducing nitrogen;

[0096] b) closing the overflow pipe 7, opening the first gate valve 10 below the bottom outlet 9, and unloading the solid-containing liquid into the transfer hopper 11;

[0097] c) increasing the solvent flow rate of the flushing pipe 8, preferably using a jet nozzle to flush the pipe, flushing the residual slurry at the bottom of the reactor, and then closing the first gate valve 10;

[0098] d) adjusting the pressure of the transfer hopper 11 (nitrogen filling or discharge) to meet the downstream reaction requirements; then opening the second gate valve 10 under the transfer hopper 11 to output the slurry.

[0099] The excess phosgene and the generated HCl flowing out of the gas outlet 2 at the top of the reactor in step 11) can be separated and recovered downstream.

[0100] Example 1

[0101] 1) A chlorobenzene solution of toluenediamine (TDA) with a mass concentration of 17%, a feed flow rate of 40 kg / h, a feed temperature of 50° C. is sprayed into the reactor from a feed atomizing nozzle 1 with a spray angle of 60°, uniformly distributed over the cross section of the reactor.

[0102] 2) Phosgene is introduced into the cold phosgene feed pipe 4 at a flow rate of about 35 kg / h and an inlet temperature of 20° C. Phosgene and amine solution mist in the reactor contact each other in reverse direction, react rapidly and release heat, and the temperature of the cold phosgene gasification reaction section is about 90° C.

[0103] 3) Phosgene is introduced into the secondary phosgene feed pipe 5 at a flow rate of about 33 kg / h and an inlet temperature of 20° C. The descending droplets in step 2) further undergo phosgenation reaction at high temperature in reverse direction, which is called the high-temperature phosgenation reaction section, and the main reaction is the phosgenation of amine hydrochloride to form formyl chloride;

[0104] 4) adjusting the cooling nozzle 6 to spray chlorobenzene, a normal temperature solvent, to control the temperature of the high temperature phosgenation reaction section to not exceed 140° C.;

[0105] 5) A small part of the droplets will adhere to the inner wall of the reactor during the process of falling from the top of the reactor; since the droplets of the phosgenation reaction contain solids, they accumulate on the wall and are not easy to flow down; intermittently open the wall flow loop pipes 3 at all levels, spray chlorobenzene solvent to flush along the wall, and the slurry flows into the bottom of the reactor along the wall;

[0106] 6) Adjust the flushing pipe 8 to add an appropriate amount of chlorobenzene solvent at room temperature to obtain a diluted bottom material temperature of 80-120°C;

[0107] 7) The bottom material obtained in step 6) is precipitated and separated at the bottom of the reactor, and the supernatant liquid continuously flows out from the overflow pipe 7 and enters the downstream to continue the high-temperature decomposition of formyl chloride.

[0108] The pressure at the top of the tower is maintained at 0.3-0.5 MPa. The conversion rate of toluenediamine is greater than 90% as determined by sampling at the outlet.

[0109] The above embodiments are only exemplary embodiments of the present disclosure and are not intended to limit the present disclosure. The protection scope of the present disclosure is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present disclosure within the essence and protection scope of the present disclosure, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present disclosure.

Claims

1. An organic amine phosgenation reactor, It is characterized in that From top to bottom, they include: A feed atomizing nozzle, which is arranged at the center of the top of the reactor and is used for feeding the organic amine solution, wherein the feed atomizing nozzle is a single nozzle, or a combination of multiple nozzles or a multi-hole nozzle; A gas outlet, which is located at the top edge of the reactor and is used to discharge excess phosgene and produced HCl; The first and second wall flow loop pipes are arranged on the reactor wall, and the angle between them and the reactor wall is 30-60 degrees, wherein the first wall flow loop pipe is located at the upper part of the reactor, and the second wall flow loop pipe is located at the middle part of the reactor, and is used to spray solvent to flush the solids attached to the reactor wall, so that the solids become slurry and flow down the wall; A cold light gas feed pipe, which is located at the upper part of the reactor, and the outlet is located on the central axis of the reactor and is bent downward, and is used to introduce cold light gas into the reactor; The first cooling nozzle is located 100-400 mm below the cold light gas feed pipe and is a group of nozzles arranged on the reactor wall, which is used to spray low-temperature atomized solvent into the reactor to control the reaction temperature of this section. This group of nozzles is located at the same height of the reactor and is evenly distributed along the radial direction of the reactor. The first cooling nozzle includes at least 2 nozzles, each nozzle is obliquely downwardly pointed to the center of the reactor, and the angle between the nozzle and the reactor wall is 20-80°; A secondary phosgene feed pipe, which is located in the middle of the reactor, and has an outlet located on the central axis of the reactor and bent downward, and is used to introduce phosgene into the reactor; The second cooling nozzle is located 100-400 mm below the secondary phosgene feed pipe and is a group of nozzles arranged on the reactor wall, and is used to spray low-temperature atomized solvent into the reactor to control the reaction temperature of this section. This group of nozzles is located at the same height of the reactor and is evenly distributed along the radial direction of the reactor. The second cooling nozzle includes at least 2 nozzles, each nozzle is obliquely downwardly pointed to the center of the reactor, and the angle between the nozzle and the reactor wall is 20-80°; Flushing pipes, which are located at the lower part of the reactor and are evenly distributed along the reactor wall at the same height, with a number of 2-12, and are used to flush the solids deposited at the bottom of the reactor; An overflow pipe, located at the bottom of the reactor, is used to discharge the clear liquid from the bottom of the reactor; Bottom outlet; first and second gate valves; and Transfer hopper; The first and second gate valves, the transfer hopper and the bottom outlet together constitute a slurry discharge structure, wherein the upper inlet of the transfer hopper is connected to the bottom outlet through the first gate valve, and the lower outlet of the transfer hopper is discharged through the second gate valve.

2. The organic amine phosgenation reactor according to claim 1, It is characterized in that The spray angle of the feed atomizing nozzle is 40-120°; and / or The feed atomizing nozzle is configured so that the sprayed liquid mist is in the shape of a solid cone and evenly distributed, and the sprayed liquid mist covers an area smaller than and close to the diameter of the reactor; and / or The feed atomizing nozzle is configured to produce a droplet size of 10-400 μm.

3. The organic amine phosgenation reactor according to claim 2, It is characterized in that The spray angle of the feed atomizing nozzle is 60-100°; and / or The feed atomizing nozzle is configured to produce a droplet size of 10-200 μm.

4. The organic amine phosgenation reactor according to claim 2, It is characterized in that The feed atomizing nozzle is set to produce a droplet size of 20-100 μm.

5. The organic amine phosgenation reactor according to claim 1, It is characterized in that The outlets of the cold phosgene feed pipe and the secondary phosgene feed pipe are bent downward at 90 degrees.

6. The organic amine phosgenation reactor according to claim 1, It is characterized in that The first cooling nozzle and the second cooling nozzle each independently include 4-8 nozzles.

7. The organic amine phosgenation reactor according to claim 1, It is characterized in that The number of the flushing pipes is 4-6.

8. The organic amine phosgenation reactor according to claim 1, It is characterized in that The wall flow annular tube is installed coaxially with the reactor, with an outer diameter of 0.8-0.98 times the inner diameter of the reactor and an inner diameter of no more than 75% of the inner diameter of the reactor. The outer side of the annular tube is evenly distributed with holes slightly inclined downward or provided with multiple downward spraying nozzles, so that the sprayed solvent flushes the inner wall of the reactor in a jet shape.

9. The organic amine phosgenation reactor according to claim 1, It is characterized in that The flushing tube is a jet type flushing tube.

10. A phosgenation reaction process, It is characterized in that The organic amine phosgenation reactor according to any one of claims 1 to 9 comprises the following steps: (1) preparing an organic amine solution with a mass concentration of 10-70%, controlling the feed temperature to 0-65°C after heat exchange, and spraying it downward into the reactor from a feed atomizing nozzle with a spray angle of 20-160°. The sprayed liquid mist is in the shape of a solid cone and is evenly distributed in the cross section of the reactor. The droplet size is 10-400 μm; (2) introducing phosgene from a cold phosgene feed pipe, wherein the molar ratio of phosgene to organic amine is 2-15, and the phosgene feed temperature is controlled at -10-65°C, and the phosgene and organic amine solution mist contact each other in reverse and react to release heat; (3) controlling the reaction temperature of this stage to not exceed 180° C. and not exceed the boiling point of formyl chloride by controlling the flow rate, concentration and inlet temperature of the organic amine solution and the feed temperature and flow rate of the cold phosgene; (4) After the first stage of cold light gasification, the droplets contain formyl chloride, amine hydrochloride and unreacted organic amine, and the droplets fall from top to bottom into the second stage of the reactor for further reaction; (5) introducing phosgene from a secondary phosgene feed pipe, wherein the molar ratio of phosgene to organic amine is 2-10, and the phosgene feed temperature is controlled at 20-160° C., and the phosgene and the droplets are in reverse contact at high temperature in the second stage of the reactor to continue phosgenation reaction to generate formyl chloride, accompanied by a decomposition reaction of the formyl chloride; (6) controlling the phosgene feed temperature and flow rate of the secondary phosgene feed pipe, as well as the amount and temperature of the solvent sprayed by the first cooling nozzle under the cold phosgene feed pipe, to ensure that the second stage reaction temperature does not exceed the boiling point of formyl chloride; (7) intermittently or continuously opening the first and second wall flow loops, spraying solvent along the wall surface for flushing, so as to dilute the viscous slurry accumulated on the wall surface and finally flow into the bottom of the reactor; (8) Open the flushing pipe, adjust the solvent feed amount and feed temperature according to the solid content and material temperature of the bottom material, and maintain the feed temperature at 20-120° C. so that the solvent and the bottom material do not exceed the boiling point of formyl chloride after mixing; (9) The reacted materials are precipitated and separated at the bottom of the reactor, and the supernatant continues to flow out from the overflow port at the bottom of the reactor; (10) After the solid solution is enriched at the bottom of the reactor, a discharging operation is performed; (11) Excess phosgene and produced HCl flow out from the gas outlet at the top of the reactor.

11. The phosgenation reaction process according to claim 10, It is characterized in that In step (1), the mass concentration of the organic amine solution is 20-50%; and / or In step (2), the molar ratio of phosgene to organic amine is 3-6; and / or In step (3), the reaction temperature of this stage is controlled to be 80-150°C; and / or In step (5), the molar ratio of phosgene to organic amine is 3-6.

12. The phosgenation reaction process according to claim 10, It is characterized in that The discharging operation of step (10) is carried out as follows: a) First, open the nitrogen filling valve of the transfer hopper, and start to introduce nitrogen into the hopper according to the pressure of the reactor until the pressure in the hopper is balanced with that in the reactor, and then stop introducing nitrogen; b) closing the overflow port, opening the first gate valve below the bottom outlet, and unloading the solid-containing liquid into the transfer hopper; c) increasing the solvent flow rate of the flushing pipe to flush the residual slurry at the bottom of the reactor, and then closing the first gate valve; d) Adjust the pressure of the transfer hopper to meet the downstream reaction requirements; then open the second gate valve under the transfer hopper to output the slurry.

13. The phosgenation reaction process according to claim 12, It is characterized in that In step c), the flushing pipe is a jet nozzle flushing pipe.

Images