A system for preparing p-fluorobenzaldehyde by hydrolyzing p-fluorodichlorobenzene

Abstract

The application discloses a system for preparing p-fluorobenzaldehyde by hydrolyzing p-fluorodichlorobenzene, which comprises an aldehyde hydrolysis kettle, a concentrated sulfuric acid metering tank, a p-fluorodichlorobenzene metering and dropping tank, a heat exchanger, a dilute sulfuric acid transition tank and a p-fluorobenzaldehyde crude product washing water transition tank, the aldehyde hydrolysis kettle is communicated with the concentrated sulfuric acid metering tank, the aldehyde hydrolysis kettle is communicated with a gas inlet of the heat exchanger, the heat exchanger is communicated with the aldehyde hydrolysis kettle, the p-fluorodichlorobenzene metering and dropping tank is communicated with a liquid inlet of the aldehyde hydrolysis kettle, and a process water storage tank is communicated with the aldehyde hydrolysis kettle through a sixth pipeline; the aldehyde hydrolysis kettle is communicated with the p-fluorobenzaldehyde crude product washing water transition tank and the dilute sulfuric acid transition tank, and liquid outlets of the p-fluorobenzaldehyde crude product washing water transition tank and the dilute acid transition tank are respectively communicated with liquid inlets of the aldehyde hydrolysis kettle. The system can realize quantitative reaction of water and p-fluorodichlorobenzene, reduce loss of materials and water, simultaneously, there is no dilute sulfuric acid and wastewater discharge, and green synthesis of p-fluorobenzaldehyde by hydrolyzing p-fluorodichlorbenzene is realized.

Description

Technical Field

[0001] This invention relates to the field of hydrolysis aldehyde reaction technology, specifically to a system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl. Background Technology

[0002] p-Fluorobenzaldehyde, with the molecular formula C7H5FO and a molecular weight of 124, is a colorless to pale yellow transparent liquid. It is an important fine chemical intermediate and is used as a main raw material for the synthesis of various pesticides, pharmaceuticals, surfactants, polymer monomers, and fungicides.

[0003] p-Fluorobenzaldehyde is a commonly used aromatic aldehyde in industry. Currently available synthesis methods include the following: chlorination hydrolysis, gas-phase oxidation, and liquid-phase oxidation.

[0004] Whether it is gas-phase oxidation or liquid-phase oxidation, due to poor oxidation selectivity (no dedicated catalyst), it is impossible to obtain high-purity p-fluorobenzaldehyde products. Many side reactions lead to low product yield, resulting in excessively high production costs.

[0005] The chlorination-hydrolysis method is currently the main industrial method, which includes two steps: chlorination and hydrolysis. p-Fluorotoluene is photochlorinated under a catalyst to obtain a mixture of benzyl chloride, benzyl dichloride and benzyl trichloride, which is then distilled to obtain p-fluorodichlorobenzyl, and hydrolyzed to obtain p-fluorobenzaldehyde.

[0006] The conventional process for preparing p-fluorobenzaldehyde via chlorination hydrolysis is as follows: 1) Pump metered p-fluorotoluene into the photochlorination reactor, add metered catalyst into the reactor through a solid feeder, and carry out photochlorination reaction under ultraviolet light irradiation and atmospheric pressure by passing chlorine gas through the reactor to obtain a mixture of benzyl chloride, benzyl dichloride and benzyl trichloride.

[0007] 2) After the photochlorination reaction is completed, the chlorinated liquid is sent to the chlorination product distillation kettle through the pipeline for heating and distillation. The first fraction is mainly p-fluorobenzyl chloride (including p-fluorodichlorobenzyl), which is collected and reused in the photochlorination reaction. The middle fraction is p-fluorodichlorobenzyl, which is used for the synthesis of p-fluorobenzaldehyde.

[0008] 3) Pump metered water and 98% concentrated sulfuric acid into the aldehyde hydrolysis reactor, and slowly add benzyl fluoride at 60-80℃ to start the aldehyde hydrolysis reaction. The waste gas generated during the aldehyde hydrolysis process is collected and recovered by falling film absorption to obtain crude hydrochloric acid. The tail gas enters the workshop waste gas treatment system.

[0009] 4) After the hydrolysis reaction is complete, water is pumped in and allowed to stand for stratification. Dilute sulfuric acid is used as waste acid for resource utilization or treated as waste. The organic layer is pumped into the water separation vessel. An appropriate amount of 30% sodium hydroxide solution is added to the water separation vessel to adjust the pH and allow it to stand for stratification.

[0010] 5) The organic phase after alkali washing is transferred into a redistiller and distilled under reduced pressure to obtain p-fluorobenzaldehyde product.

[0011] In order to ensure the complete reaction and prevent polymerization accidents caused by lack of water in the reaction system, conventional aldehyde hydrolysis production often adds excess water and sulfuric acid (excess concentrated sulfuric acid to ensure the sulfuric acid concentration required for the reaction) before the reaction. Therefore, after the aldehyde hydrolysis is completed, a large amount of dilute sulfuric acid is generated, which causes great environmental pressure and also results in the loss of sulfuric acid and some products, which does not meet the requirements of green chemical industry. Summary of the Invention

[0012] To address the existing technical problems, this invention provides a system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl, thereby solving the problems in the prior art.

[0013] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl includes an aldehyde hydrolysis reactor, a concentrated sulfuric acid metering tank, a p-fluorodichlorobenzyl metering and dropping tank, a heat exchanger, a dilute sulfuric acid transition tank, and a p-fluorobenzaldehyde crude product washing water transition tank. The inlet of the aldehyde hydrolysis reactor is connected to the concentrated sulfuric acid metering tank via a first pipe, and the first pipe is equipped with a first flow meter and a first regulating valve. The outlet of the aldehyde hydrolysis reactor is connected to the inlet of the heat exchanger via a second pipe, and the outlet of the heat exchanger is connected to the aldehyde hydrolysis reactor via a third pipe. The heat exchanger is equipped with a first cooling... The system includes a water inlet pipe and a first cooling water return pipe. The metering and dripping tank for p-dichlorobenzyl fluoride is connected to the inlet of the aldehyde hydrolysis reactor via a fourth pipe. The fourth pipe is equipped with a second flow meter, a second regulating valve, and an emergency shut-off valve. The metering and dripping tank for p-dichlorobenzyl fluoride is connected to the workshop exhaust gas treatment mechanism via a first vent pipe. The outlet of the heat exchanger is connected to the workshop exhaust gas treatment mechanism via a fifth pipe. The process water storage tank is connected to the aldehyde hydrolysis reactor via a sixth pipe. The sixth pipe is equipped with a third flow meter and a third regulating valve. The aldehyde hydrolysis reactor is equipped with a stirrer. The outlet of the aldehyde hydrolysis reactor is connected to the dehydration and alkali washing reactor via a seventh pipe. The outlet of the aldehyde hydrolysis reactor is connected to the washing water transition tank of the crude p-fluorobenzaldehyde via an eighth pipe. The outlet of the aldehyde hydrolysis reactor is also connected to the dilute sulfuric acid transition tank via a ninth pipe. The outlets of the washing water transition tank of the crude p-fluorobenzaldehyde and the dilute sulfuric acid transition tank are connected to the inlet of the aldehyde hydrolysis reactor via a tenth pipe. A circulation pump is installed on the tenth pipe.

[0014] Preferably, the crude p-fluorobenzaldehyde washing water transition tank is equipped with a fourth level gauge, which is electrically connected to the circulating pump.

[0015] Preferably, the dilute sulfuric acid transition tank is equipped with a fifth level gauge, which is electrically connected to the circulating pump.

[0016] Preferably, the aldehyde hydrolysis reactor is connected to a nitrogen storage tank via an eleventh pipeline, and a fourth regulating valve is provided on the eleventh pipeline.

[0017] Preferably, the aldehyde hydrolysis reactor is fitted with a jacket around its outer periphery, the inlet of the jacket is connected to a steam pipe, the steam pipe is equipped with a fifth regulating valve, the outlet of the jacket is connected to a condensate pipe, and the condensate pipe is equipped with a sixth regulating valve and a drain valve.

[0018] Preferably, the outlet of the jacket is connected to a second cooling water inlet pipe, which is equipped with a seventh regulating valve, and the inlet of the jacket is connected to a second cooling water return pipe, which is equipped with an eighth regulating valve.

[0019] Preferably, the crude p-fluorobenzaldehyde washing water transition tank is connected to the workshop exhaust gas treatment mechanism via a second vent pipe.

[0020] Preferably, the dilute sulfuric acid transition tank is connected to the workshop exhaust gas treatment mechanism via a third vent pipe.

[0021] Preferably, the concentrated sulfuric acid metering tank is equipped with a second level gauge, and the concentrated sulfuric acid metering tank is connected to the concentrated sulfuric acid storage tank through a twelfth pipe. The twelfth pipe is equipped with a ninth regulating valve, which is electrically connected to the second level gauge.

[0022] Preferably, the metering and dropping tank for benzyl fluoride is equipped with a third level gauge, and the metering and dropping tank for benzyl fluoride is connected to a chlorination distillation tower through a thirteenth pipeline. The thirteenth pipeline is equipped with a tenth regulating valve, which is electrically connected to the third level gauge.

[0023] Compared with existing technologies, the beneficial effects of this invention are as follows: This solution adds a heat exchanger to the aldehyde hydrolysis reactor to ensure that the water vapor and p-fluorobenzaldehyde after vaporization during the reaction are condensed and returned to the aldehyde hydrolysis reactor, reducing material and water losses and achieving quantitative reaction of water and p-fluorobenzyl chloride. Simultaneously, process water is quantitatively added to the aldehyde hydrolysis reactor after the reaction, achieving precise stratification of sulfuric acid and p-fluorobenzaldehyde. A dilute sulfuric acid transition tank and a p-fluorobenzaldehyde crude product washing water transition tank are set up to circulate the stratified dilute sulfuric acid and washing water (without external discharge of dilute sulfuric acid and wastewater), realizing the green synthesis of p-fluorobenzaldehyde from p-fluorobenzyl chloride hydrolysis. This improves the safety of the p-fluorobenzyl chloride hydrolysis process, reduces production costs, and also reduces environmental pollution. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0026] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0027] As attached Figure 1 The system shown is for the hydrolysis of p-fluorobenzyl dichlorofluorocarbon to prepare p-fluorobenzaldehyde, including an aldehyde hydrolysis reactor 1, a concentrated sulfuric acid metering tank 13, a p-fluorobenzyl dichlorofluorocarbon metering and dropping tank 21, a heat exchanger 29, a dilute sulfuric acid transition tank 44, and a p-fluorobenzaldehyde crude product washing water transition tank 51. The inlet of the aldehyde hydrolysis reactor 1 is connected to the concentrated sulfuric acid metering tank 13 through a first pipe 16. The first pipe 16 is equipped with a first flow meter 17 and a first regulating valve 18. The outlet of the aldehyde hydrolysis reactor 1 is connected to the inlet of the heat exchanger 29 through a second pipe 28. The outlet of the heat exchanger 29 is connected to the aldehyde hydrolysis reactor 1 through a third pipe 32. The heat exchanger 29 is equipped with... The first cooling water inlet pipe 30 and the first cooling water return pipe 31 are connected to the inlet of the aldehyde hydrolysis reactor 1 via the fourth pipe 24. The fourth pipe 24 is equipped with a second flow meter 25, a second regulating valve 27 and an emergency shut-off valve 26. The outlet of the heat exchanger 29 is connected to the workshop exhaust gas treatment mechanism 55 via the fifth pipe 33. The process water storage tank is connected to the aldehyde hydrolysis reactor 1 via the sixth pipe 7. The sixth pipe 7 is equipped with a third flow meter 8 and a third regulating valve 9. The aldehyde hydrolysis reactor 1 is equipped with a stirrer 10. The outlet of the aldehyde hydrolysis reactor 1 is connected to the dehydration and alkali washing reactor via the seventh pipe 54.

[0028] The outlet of the aldehyde hydrolysis reactor 1 is connected to the p-fluorobenzaldehyde crude product washing water transition tank 51 via the eighth pipe 50. The outlet of the aldehyde hydrolysis reactor 1 is also connected to the dilute sulfuric acid transition tank 44 via the ninth pipe 43. The outlets of the p-fluorobenzaldehyde crude product washing water transition tank 51 and the dilute sulfuric acid transition tank 44 are connected to the inlet of the aldehyde hydrolysis reactor 1 via the tenth pipe 49. A circulation pump 48 is installed on the tenth pipe 49. A fourth level gauge 52 is installed on the p-fluorobenzaldehyde crude product washing water transition tank 51, and a fifth level gauge 45 is installed on the dilute sulfuric acid transition tank 44. The circulation pump 48 is electrically connected to both the fourth and fifth level gauges. The p-fluorobenzaldehyde crude product washing water transition tank 51 is connected to the workshop exhaust gas treatment mechanism 55 via the second vent pipe 53. The dilute sulfuric acid transition tank 44 is connected to the workshop exhaust gas treatment mechanism 55 via the third vent pipe 46.

[0029] The aldehyde hydrolysis reactor 1 is connected to a nitrogen storage tank via an eleventh pipe 5, which is equipped with a fourth regulating valve 6. After the reaction of the material in the aldehyde hydrolysis reactor 1 is completed, nitrogen gas is introduced into the material in the aldehyde hydrolysis reactor 1 through the eleventh pipe 5 and the fourth regulating valve 6 to expel the residual hydrogen chloride gas.

[0030] The aldehyde hydrolysis reactor 1 is fitted with a jacket 101. The inlet of the jacket 101 is connected to a steam pipe 34, and a fifth regulating valve 35 is installed on the steam pipe 34. The outlet of the jacket 101 is connected to a condensate pipe 38, and a sixth regulating valve 36 and a steam trap 37 are installed on the condensate pipe 38. The outlet of the jacket 101 is connected to a second cooling water inlet pipe 39, and a seventh regulating valve 40 is installed on the second cooling water inlet pipe 39. The inlet of the jacket 101 is connected to a second cooling water return pipe 42, and an eighth regulating valve 41 is installed on the second cooling water return pipe 42. The aldehyde hydrolysis reactor 1 is equipped with a pressure gauge 3, a thermometer 4, and a first level gauge 2. The thermometer 4 is electrically connected to the fifth regulating valve 35, the sixth regulating valve 36, the seventh regulating valve 40, and the eighth regulating valve 41, respectively.

[0031] A second level gauge 14 is installed on the concentrated sulfuric acid metering tank 13. The concentrated sulfuric acid metering tank 13 is connected to the concentrated sulfuric acid storage tank through the twelfth pipe 11. A ninth regulating valve 12 is installed on the twelfth pipe 11. The ninth regulating valve 12 is electrically connected to the second level gauge 14.

[0032] The benzyl difluorofluoride metering and dripping tank 21 is connected to the workshop exhaust gas treatment mechanism 55 through the first vent pipe 23. The benzyl difluorofluoride metering and dripping tank 21 is equipped with a third level gauge 22. The benzyl difluorofluoride metering and dripping tank 21 is connected to the chlorination distillation tower through the thirteenth pipe 19. The thirteenth pipe 19 is equipped with a tenth regulating valve 20, which is electrically connected to the third level gauge 22.

[0033] The principle of this embodiment is as follows: The raw material concentrated sulfuric acid from the concentrated sulfuric acid tank area enters the concentrated sulfuric acid metering tank 13 through the twelfth pipeline 11 and the ninth regulating valve 12. The concentrated sulfuric acid is interlocked and controlled by the second level gauge 14 and the ninth regulating valve 12 to prevent the concentrated sulfuric acid level from being too high and overflowing into the tank. Concentrated sulfuric acid in concentrated sulfuric acid metering tank 13 is quantitatively added to aldehyde hydrolysis reactor 1 through first flow meter 17 and first regulating valve 18 via first pipeline 16, and stirred under the action of stirrer 10; process water is quantitatively added to aldehyde hydrolysis reactor 1 through sixth pipeline 7, third flow meter 8 and third regulating valve 9 to prepare dilute sulfuric acid of appropriate concentration as specified in the process, which is used to prepare p-fluorobenzaldehyde by hydrolysis of dichlorofluorobenzyl. The feedstock p-dichlorobenzyl fluoride from the chlorination distillation column enters the p-dichlorobenzyl fluoride metering and dropping tank 21 through the thirteenth pipeline 19 and the tenth regulating valve 20. The p-dichlorobenzyl fluoride is interlocked with the third level gauge 22 and the tenth regulating valve 20 to prevent the p-dichlorobenzyl fluoride level from being too high and overflowing into the tank. p-Dichlorobenzyl fluorocarbonate in metering and dropping tank 21 is quantitatively added into aldehyde hydrolysis reactor 1 through fourth pipeline 24, second flow meter 25, emergency shut-off valve 26, second regulating valve 27 and pipeline, and hydrolysis reaction is carried out under sulfuric acid catalysis to obtain p-fluorobenzaldehyde and hydrogen chloride gas. Before the addition of aldehyde hydrolysis, steam enters the jacket of the aldehyde hydrolysis reactor 1 through steam pipe 34 and fifth regulating valve 35 to heat the sulfuric acid in the aldehyde hydrolysis reactor 1. The steam condensate is discharged through sixth regulating valve 36, steam trap 37 and condensate pipe 38. Fifth regulating valve 35, sixth regulating valve 36 and thermometer 4 are interlocked to achieve temperature control.

[0034] The hydrogen chloride gas, water vapor, and vaporized p-fluorobenzaldehyde produced in the aldehyde hydrolysis reactor 1 enter the heat exchanger 29 through the second pipe 28. After being cooled by cooling water, the condensed water vapor and p-fluorobenzaldehyde are returned to the aldehyde hydrolysis reactor 1 through the third pipe 32 to prevent the material in the aldehyde hydrolysis reactor 1 from polymerizing due to excessive sulfuric acid concentration caused by water loss. The condensed hydrogen chloride gas enters the workshop exhaust gas treatment unit 55 through the fifth pipe 33 for the preparation of hydrochloric acid. After the reaction of the materials in the aldehyde hydrolysis reactor 1 is completed, nitrogen gas is introduced into the aldehyde hydrolysis reactor 1 through the eleventh pipe 5 and the fourth regulating valve 6 to expel the residual hydrogen chloride gas.

[0035] A quantitative amount of process water is introduced into the aldehyde hydrolysis reactor 1 via the sixth pipe 7, the third flow meter 8, and the third regulating valve 9, or the washing water from the p-fluorobenzaldehyde crude washing water transition tank 51 is introduced into the reactor via the circulating pump 48 and the tenth pipe 49. The sulfuric acid in the reacted material is diluted to separate p-fluorobenzaldehyde and dilute sulfuric acid into layers. The lower layer of dilute sulfuric acid is transferred into the dilute sulfuric acid transition tank 44 via the ninth pipe 43. Then, a quantitative amount of process water is introduced into the aldehyde hydrolysis reactor 1 via the sixth pipe 7, the third flow meter 8, and the third regulating valve 9 to wash the p-fluorobenzaldehyde crude product and allow it to stand and separate into layers. The aqueous phase obtained from the separation is transferred into the p-fluorobenzaldehyde crude product washing water transition tank 51 via the eighth pipe 50, while the organic phase is transferred into the water separation and alkaline washing reactor via the seventh pipe 54 for the post-treatment water separation and alkaline washing process.

[0036] A fourth level gauge 52 is installed on the crude fluorobenzaldehyde washing water transfer tank 51 and is interlocked with the circulating pump 48 to prevent the circulating pump 48 from running dry and causing pump damage; a fifth level gauge 45 is installed on the dilute sulfuric acid transfer tank 44 and is interlocked with the circulating pump 48 to prevent the circulating pump 48 from running dry and causing pump damage.

[0037] A first vent pipe 23 is provided on the metering and dropping tank 21 for benzyl fluoride dichloro, a third vent pipe 46 is provided on the dilute sulfuric acid transition tank 44, and a second vent pipe 53 is provided on the crude benzaldehyde washing water transition tank 51. The first vent pipe 23, the third vent pipe 46, the second vent pipe 53, and the fifth pipe 33 are connected together to the workshop exhaust gas treatment mechanism for the preparation of hydrochloric acid.

[0038] This scheme adds a heat exchanger to the aldehyde hydrolysis reactor to ensure that the water vapor and p-fluorobenzaldehyde produced during the reaction are condensed and returned to the reactor, reducing material and water loss and achieving a quantitative reaction between water and p-fluorobenzyl chloride. Furthermore, water is quantitatively added to the aldehyde hydrolysis reactor after the reaction to achieve precise stratification of sulfuric acid and p-fluorobenzaldehyde. A dilute sulfuric acid transfer tank and a crude p-fluorobenzaldehyde washing water transfer tank are set up to circulate the stratified dilute sulfuric acid and washing water (without external discharge of dilute sulfuric acid and wastewater), achieving a green synthesis of p-fluorobenzaldehyde from the hydrolysis of p-fluorobenzyl chloride. This improves the safety of the p-fluorobenzyl chloride hydrolysis process and simultaneously achieves the recycling of sulfuric acid during production, reducing production costs and environmental pollution.

[0039] The preferred embodiments of the present invention have been described above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl, characterized in that: The system includes an aldehyde hydrolysis reactor (1), a concentrated sulfuric acid metering tank (13), a p-fluorobenzyl chloride metering and dropping tank (21), a heat exchanger (29), a dilute sulfuric acid transition tank (44), and a p-fluorobenzaldehyde crude product washing water transition tank (51). The inlet of the aldehyde hydrolysis reactor (1) is connected to the concentrated sulfuric acid metering tank (13) through a first pipe (16). The first pipe (16) is equipped with a first flow meter (17) and a first regulating valve (18). The outlet of the aldehyde hydrolysis reactor (1) is connected to the inlet of the heat exchanger (29) through a second pipe (28). The outlet of the heat exchanger (29) is connected to the aldehyde hydrolysis reactor (1) through a third pipe (32). The heat exchanger (29) is equipped with a first cooling water inlet pipe (30) and a first cooling water... The return water pipe (31) is connected to the inlet of the aldehyde hydrolysis kettle (1) via the fourth pipe (24). The fourth pipe (24) is equipped with a second flow meter (25), a second regulating valve (27) and an emergency shut-off valve (26). The aldehyde hydrolysis kettle (21) is connected to the workshop exhaust gas treatment mechanism (55) via the first vent pipe (23). The outlet of the heat exchanger (29) is connected to the workshop exhaust gas treatment mechanism (55) via the fifth pipe (33). The process water storage tank is connected to the aldehyde hydrolysis kettle (1) via the sixth pipe (7). The sixth pipe (7) is equipped with a third flow meter (8) and a third regulating valve (9). The aldehyde hydrolysis kettle (1) is equipped with a stirrer (10). The outlet of the aldehyde hydrolysis reactor (1) is connected to the dehydration and alkali washing reactor via the seventh pipe (54). The outlet of the aldehyde hydrolysis reactor (1) is connected to the p-fluorobenzaldehyde crude product washing water transition tank (51) via the eighth pipe (50). The outlet of the aldehyde hydrolysis reactor (1) is also connected to the dilute sulfuric acid transition tank (44) via the ninth pipe (43). The outlet of the p-fluorobenzaldehyde crude product washing water transition tank (51) and the dilute sulfuric acid transition tank (44) are connected. The outlet of the ) is connected to the inlet of the aldehyde hydrolysis vessel (1) through the tenth pipe (49), and the tenth pipe (49) is equipped with a circulation pump (48); the crude p-fluorobenzaldehyde washing water transition tank (51) is equipped with a fourth level gauge (52), which is electrically connected to the circulation pump (48); the dilute sulfuric acid transition tank (44) is equipped with a fifth level gauge (45), which is electrically connected to the circulation pump (48).

2. The system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl according to claim 1, characterized in that: The aldehyde hydrolysis vessel (1) is connected to the nitrogen storage tank through the eleventh pipe (5), and the eleventh pipe (5) is equipped with a fourth regulating valve (6).

3. The system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl according to claim 1, characterized in that: The aldehyde hydrolysis reactor (1) is fitted with a jacket (101) on its outer periphery. The inlet of the jacket (101) is connected to a steam pipe (34). A fifth regulating valve (35) is provided on the steam pipe (34). The outlet of the jacket (101) is connected to a condensate pipe (38). A sixth regulating valve (36) and a drain valve (37) are provided on the condensate pipe (38).

4. The system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl according to claim 3, characterized in that: The outlet of the jacket (101) is connected to the second cooling water inlet pipe (39), and the second cooling water inlet pipe (39) is provided with a seventh regulating valve (40). The inlet of the jacket (101) is connected to the second cooling water return pipe (42), and the second cooling water return pipe (42) is provided with an eighth regulating valve (41).

5. The system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl according to claim 1, characterized in that: The crude p-fluorobenzaldehyde washing water transition tank (51) is connected to the workshop exhaust gas treatment mechanism (55) through the second vent pipe (53).

6. The system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl according to claim 1, characterized in that: The dilute sulfuric acid transition tank (44) is connected to the workshop exhaust gas treatment mechanism (55) through the third vent pipe (46).

7. The system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl according to claim 1, characterized in that: The concentrated sulfuric acid metering tank (13) is equipped with a second level gauge (14). The concentrated sulfuric acid metering tank (13) is connected to the concentrated sulfuric acid storage tank through a twelfth pipe (11). The twelfth pipe (11) is equipped with a ninth regulating valve (12). The ninth regulating valve (12) is electrically connected to the second level gauge (14).

8. The system for preparing p-fluorobenzaldehyde by hydrolysis of p-fluorodichlorobenzyl according to claim 7, characterized in that: The metering and dripping tank (21) for dichlorofluorocarbon is equipped with a third level gauge (22). The metering and dripping tank (21) for dichlorofluorocarbon is connected to the chlorination distillation tower through the thirteenth pipeline (19). The thirteenth pipeline (19) is equipped with a tenth regulating valve (20), which is electrically connected to the third level gauge (22).

Images