WO2015032235A1

WO2015032235A1 - Rectification method for 3,5-dichloro-4-aminotrifluorotoluene, and light tower system and rectification tower system used in rectification method

Info

Publication number: WO2015032235A1
Application number: PCT/CN2014/079943
Authority: WO
Inventors: 江耀田; 杨劲松; 冯进
Original assignee: 南通市海圣药业有限公司
Priority date: 2013-09-05
Filing date: 2014-06-16
Publication date: 2015-03-12
Also published as: CN103483207A; CN103483207B

Abstract

Disclosed are a rectification method for 3,5-dichloro-4-aminotrifluorotoluene and a light tower system and a rectification tower system used in the rectification method. The rectification method for 3,5-dichloro-4-aminotrifluorotoluene comprises the following steps: checking each piece of equipment, and performing a pressure test on the systems; adding materials; opening a steam inlet valve of the light tower and a steam trap bypass valve of the light tower to thoroughly drain it of condensed water, opening a steam trap stop valve of the light tower, and closing the steam trap bypass valve of the light tower; refluxing, opening a pre-distillation extraction valve, and extracting to a pre-distillation kettle; and feeding the materials into a rectification tower, refluxing, sampling, and extracting the finished product to a finished product receiving tank. The light tower system comprises the light tower, the pre-distillation kettle and a light tower distillation kettle; and the rectification tower system comprises the rectification tower, a rectification tower distillation kettle and the finished product receiving tank. The present invention has the following beneficial effects: raw materials are saved, the final yield is increased, the amount of kettle residue is greatly reduced, and a considerable economic benefit is obtained; meanwhile, the dangerous solid waste treatment and transfer amounts are reduced, and good environmental benefits are obtained.

Description

Fine method of 3, 5-dichloro-4-aminobenzotrifluoride and its light tower system and fine tower system applied to the fine boring method

Technical field

The present invention relates to a fine process for 3,5-dichloro-4-aminobenzotrifluoride, relating to a light tower system for use in a fine process of 3,5-dichloro-4-aminobenzotrifluoride It also relates to a refined column system for use in a refined process of 3, 5-dichloro-4-aminobenzotrifluoride.

Say

Background technique

At present, the output of chemical products such as medicines and pesticides in China has continued to grow steadily, which in turn has led to the steady and steady growth of its synthetic intermediates, and the demand for intermediates has further expanded. The fine method in the prior art has always had poor product quality, and failed to meet the export standard (content of 99.5%). At the same time, due to poor precision, there are many dangerous wastes, which leads to high product cost. It produces dangerous solid waste and is not environmentally friendly.

Therefore, there is an urgent need for an improved technique to solve this problem in the prior art. Summary of the invention

The invention provides a fine method for 3, 5-dichloro-4-aminobenzotrifluoride with less waste of resources and good yield, and provides a fine for 3, 5-dichloro-4-aminobenzotrifluoride. The light column system in the oxime method also provides a refined column system for use in the fine sputum process of 3, 5-dichloro-4-aminobenzotrifluoride.

The technical solution adopted by the invention is:

The precise method of 3, 5-dichloro-4-aminobenzotrifluoride comprises the following steps:

a, check each equipment, system pressure test, no-load vacuum above 0. 098Mpa, within half an hour, the vacuum does not fall more than O. OlMpa;

b. Open the light tower system vacuum button and the light tower feed valve. When the material 4-amino-trifluorotoluene reaches 1000 parts by mass, close the light tower feed valve, open the stirrer machine to seal the cooling water, and start the stirring motor; c. When the vacuum degree of the light tower system reaches -0.09MPa, open the light tower steam inlet valve and the light tower steam trap bypass valve to clear the condensate, open the light tower trap shut-off valve, and close the light tower trap bypass. Valve; d. When the liquid level in the light tower reaches 2/3, the reflow of the bottom hole of the light tower occurs, and when the light tower temperature reaches 78-83 °C, the reflux timing starts, and the reflux is started after 1-1.5 hours. Exit the valve and take it out to the front kettle;

e. When the mass percentage of dichloro 3,5-dichloro-4-aminobenzotrifluoride is 5%, the temperature change at the top of the light tower is 1-5 ° C, and the feeding to the fine column system is started;

f. When the liquid level in the refining tower reaches 1/2, open the bypass trap valve of the refiner and the steam inlet valve of the refining tower, start to heat up the refining tower, and warm up to the bottom of the refining tower to have a return flow, and When the temperature reaches 78-85 °C, the reflux time starts, and the reflux time is 1-1.5 hours;

g. When the temperature of the top of the tower starts to rise and the temperature is 95-105 ° C, the outlet of the light tower reflux pump is sampled, and the mass percentage of 3, 5-dichloro-4-aminobenzotrifluoride of dichloro is used. At 97%, the finished product 3, 5-dichloro-4-aminobenzotrifluoride was started to be obtained from the finished product receiving tank;

h. Sample the light tower and the refined tower every hour, the mass percentage of the light tower chlorine is 1%, and the mass percentage of the 3, 5-dichloro-4-aminobenzotrifluoride before the fine tower is 5 %, the mass percentage of 3, 5-dichloro-4-aminobenzotrifluoride in the refined column is 99.5%, and the finished product of 3, 5-dichloro-4-aminobenzotrifluoride is 60-80 mass per hour. Share.

The temperature of the light tower and the fine tower rises slowly, the final temperature is 130-140 ° C, the temperature in the two towers is normally controlled between 120-125 ° C, and the temperature at the top of the tower is between 110-125 ° C. The system vacuum is 098 MPa.

a light tower system in a fine process of 3, 5-dichloro-4-aminobenzotrifluoride, the light tower system comprising a light tower, a front crucible and a light tower steaming kettle, the light towers respectively connected to the light tower a steaming kettle, a light tower feed pump, a light tower condenser, a light tower reflux tank and a front crucible, the light tower steaming kettle is connected to a light tower steam trap valve, and the light tower steam trap valve is connected in parallel Tower trap bypass valve, the light tower steaming The steamer is connected with a light tower steam inlet valve and a stirring motor, and a light tower feed valve is arranged between the light tower and the light tower steaming kettle, and the light tower condenser is connected to a light tower tail cooler, the light tower and A light tower reflux pump is arranged between the light tower reflux tanks, and a front rake recovery valve is arranged between the light tower and the front crucible.

a refined tower system in a fine process of 3,5-dichloro-4-aminobenzotrifluoride, the fine tower system comprising a fine tower, a refined tower steaming kettle and a finished product receiving tank, the fine towers being respectively connected to the light tower a system, a refined tower steaming kettle, a refined tower condenser, a refined tower reflux tank, and a finished product receiving tank, wherein the refined tower steaming tank is connected to a fine tower steam trap valve, and the fine tower steam trap valve is connected in parallel to the fine tower hydrophobic a bypass valve, the refined tower steaming tank is connected to a fine tower steam inlet valve, the fine tower condenser is connected to a fine tower tail cooler, and a fine tower reflux pump is arranged between the fine tower and the refined tower reflux tank. The finished product receiving tank is connected to the finished mixing tank.

The beneficial effects of the invention are as follows: the raw materials are saved, the final yield is improved, the amount of the residue is greatly reduced, considerable economic benefits are obtained, and the hazardous solid waste treatment and transfer amount are reduced, and good environmental benefits are obtained.

DRAWINGS

The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

1 is a schematic structural view of a light tower system of the present invention.

Figure 2 is a schematic view showing the structure of the refined tower system of the present invention.

Among them: 1, light tower, 2, light tower steaming kettle, 3, light tower feed pump, 4, light tower condenser, 5, light tower reflux tank, 6, front crucible, 7, light tower trap Valve, 8, light tower steam trap bypass valve, 9, light tower steam inlet valve, 10, stirring motor, 1 1, light tower feed valve, 1 2, tail cooler, 1 3, light tower return pump , 1 4, front sputum production valve, 1 5, refined tower, 1 6, refined tower steaming kettle, 1 7, refined tower condenser, 1 8, refined tower reflux tank, 19, finished product receiving tank, 20, Fine tower steam trap valve, 2 1, refined tower steam trap bypass valve, 22, refined tower steam inlet valve, 2 3, refined tower tail cooler, 24, refined tower return pump, 25, finished product mixing tank.

detailed description Example 1

As shown in Figures 1 and 2, the refined method of 3,5-dichloro-4-aminobenzotrifluoride of the present invention comprises the following steps:

a. Check each equipment, open the main vacuum button of the precision tower system, vacuum valve of each tank, return tank and buffer tank vacuum valve, open the vacuum pump cooling water, open the vacuum pump, open the vacuum pump outlet valve, and slowly open the vacuum pump and inlet valve. When the system pressure reaches _0.09MPa or above, the vacuum pump is stopped, the system is tested, the no-load vacuum is above 0.098Mpa, and the vacuum is reduced by 0.00 IMpa in half an hour; b. Open the vacuum pump cooling water valve to adjust the water volume to normal flow, open Vacuum pump outlet valve, drain the liquid in the oil collector, open the vacuum pump inlet vent valve, and then open the vacuum pump. After the vacuum pump is running normally, close the vent valve, open the vacuum pump inlet valve, open the vacuum tower system vacuum button, light tower feed valve 11, when the material 4-amino-trifluorotoluene reaches 1000kg, close the light tower feed valve 11, open the agitator to seal the cooling water, start the stirring motor 10;

c. When the vacuum degree of the light tower system reaches -0.09MPa, open the light tower steam inlet valve 9, the light tower steam trap bypass valve 8 clear the condensed water, open the light tower steam trap valve 7, close the light tower drain Bypass valve 8;

d. When the liquid level in the light tower 1 reaches 2/3, the bottom tower hole of the light tower 1 is recirculated, and when the temperature of the light tower 1 reaches 78 °C, the reflux timing starts. After the reflux for 1 hour, the front and rear boring valves 14 are opened. , produced to the front of the kettle 6;

e. When the mass percentage of dichloro 3,5-dichloro-4-aminobenzotrifluoride is 5%, the temperature change at the top of the light tower 1 is 1-5 ° C, and the feeding to the fine tower system is started. 1 internal monochloro 3, 5-dichloro-4-aminobenzotrifluoride mass percentage 1%;

f. When the liquid level in the finishing tower 15 reaches 1/2, the fine tower steam trap bypass valve 21 and the fine tower steam inlet valve 22 are opened, and the fine tower 15 is heated up, and the temperature is raised to the fine tower 15 tower bottom mirror. When there is a return flow, and the temperature reaches 78 °C, the reflux time starts, and the reflux time is 1 hour; g. When the temperature at the top of the tower 15 starts to rise and the temperature is 98 °C, the outlet of the light tower reflux pump 13 is sampled, and the mass percentage of 3, 5-dichloro-4-aminobenzotrifluoride of dichloro is used. At 97%, the finished product receiving tank 19 is started to produce the finished product 3, 5-dichloro-4-aminobenzotrifluoride;

h. Sample the light tower 1 and the fine tower 15 every hour, the mass percentage of the chlorine in the light tower is 1%, and the mass of the 3, 5-dichloro-4-aminobenzotrifluoride in the former tower 15 The content of 5% is 5, the mass percentage of 3, 5-dichloro-4-aminobenzotrifluoride in the refined column 15 is 99.5%, and the yield per hour of the finished 3, 5-dichloro-4-aminobenzotrifluoride is 78kg.

The temperature of the light tower 1 and the fine tower 15 rise slowly, the final temperature is 13 CTC, the temperature in the two towers is normally controlled between 120 ° C, the temperature at the top of the tower is between 110 ° C, and the vacuum degree of the entire fine boring system is 0.098 MPa.

a light tower system in a fine process of 3, 5-dichloro-4-aminobenzotrifluoride, the light tower system comprising a light tower 1, a front crucible 6 and a light tower steaming kettle 2, the light tower 1 Connect the light tower steaming pot 2, the light tower feed pump 3, the light tower condenser 4, the light tower reflux tank 5 and the front crucible tank 6, respectively, and the light tower steaming pot 2 is connected to the light tower trap shut-off valve 7, The light tower steam trap valve 7 is connected in parallel to the light tower steam trap bypass valve 8, the light tower steamer 2 is connected to the light tower steam inlet valve 9 and the stirring motor 10, and the light tower 1 and the light tower are steamed. A light tower feed valve 11 is disposed between the crucibles 2, the light tower condenser 4 is connected to the light tower tail cooler 12, and a light tower reflux pump 13 is disposed between the light tower 1 and the light tower reflux tank 5. A front rake recovery valve 14 is provided between the light tower 1 and the front crucible 6.

a refined column system in a fine process of 3, 5-dichloro-4-aminobenzotrifluoride, the fine column system comprising a fine column 15, a refined column steaming pot 16 and a finished product receiving tank 19, the fine column 15 The light tower system, the refined tower steaming kettle 16, the refined tower condenser 17, the refined tower reflux tank 18, and the finished product receiving tank 19 are respectively connected, and the refined tower steaming pot 16 is connected to the fine tower steam trap valve 20, the fine The tower trap shutoff valve 20 is connected in parallel to the fine tower steam trap bypass valve 21, the fine tower steamer 16 is connected to the fine tower steam inlet valve 22, and the fine tower condenser 17 is connected to the fine tower tail cooler 23, Refined tower 15 and refined tower reflux tank 19 There is a fine tower return pump 14 which is connected to the finished mixing tank 25. Example 2

a. Check each equipment, open the main vacuum button of the precision tower system, vacuum valve of each tank, return tank and buffer tank vacuum valve, open the vacuum pump cooling water, open the vacuum pump, open the vacuum pump outlet valve, and slowly open the vacuum pump and inlet valve. When the system pressure reaches _0.09MPa or above, the vacuum pump is stopped, the system is pressure tested, the no-load vacuum is above 0.098Mpa, and the vacuum is reduced by 0.005Mpa within half an hour; b. Open the vacuum pump cooling water valve to adjust the water volume to normal flow, open Vacuum pump outlet valve, drain the liquid in the oil collector, open the vacuum pump inlet vent valve, and then open the vacuum pump. After the vacuum pump is running normally, close the vent valve, open the vacuum pump inlet valve, open the vacuum tower system vacuum button, light tower feed valve 11, when the material 4-amino-trifluorotoluene reaches 1000kg, close the light tower feed valve 11, open the agitator to seal the cooling water, start the stirring motor 10;

d. When the liquid level in the light tower 1 reaches 2/3, the bottom hole of the light tower 1 is recirculated, and when the temperature of the light tower 1 reaches 80 °C, the reflux timing starts, and after 1.3 hours of reflux, the front recovery valve 14 is opened. , produced to the front of the kettle 6;

e. When the mass percentage of dichloro 3,5-dichloro-4-aminobenzotrifluoride is 5%, the temperature change at the top of the light tower 1 is 2 °C, and the feed to the fine tower system is started. Monochlorinated 3, 5-dichloro-4-aminobenzotrifluoride by 1% by mass;

f. When the liquid level in the finishing tower 15 reaches 1/2, the fine tower steam trap bypass valve 21 and the fine tower steam inlet valve 22 are opened, and the fine tower 15 is heated up, and the temperature is raised to the fine tower 15 tower bottom mirror. Reflux When the temperature reaches 80 °C, the reflux time is started, and the reflux time is 1.2 hours. g. When the temperature of the top of the tower 15 starts to rise and the temperature is 100 °C, the outlet of the light tower reflux pump 13 is sampled. When the mass percentage of dichloro 3,5-dichloro-4-aminobenzotrifluoride is 97%, the finished product 3, 5-dichloro-4-aminobenzotrifluoride is started to be obtained from the finished product receiving tank 19;

h. Sample the light tower 1 and the fine tower 15 every hour, the mass percentage of the light tower 1 chlorine is 1% and the quality of the 3, 5-dichloro-4-aminobenzotrifluoride of the front tower 5% by weight, the mass percentage of 3,5-dichloro-4-aminobenzotrifluoride in the refined column 15 is 99.5%, and the yield of the finished 3, 5-dichloro-4-aminobenzotrifluoride per hour It is 65kg.

The temperature of the light tower 1 and the fine tower 15 rise slowly, the final temperature is 135 ° C, the temperature in the two towers is normally controlled between 123 ° C, the temperature at the top of the tower is between 118 ° C, and the vacuum degree of the entire fine system is 0.098. MPa.

a refined column system in a fine process of 3, 5-dichloro-4-aminobenzotrifluoride, the fine column system comprising a fine column 15, a refined column steaming pot 16 and a finished product receiving tank 19, the fine column 15 The light tower system, the refined tower steaming kettle 16, the refined tower condenser 17, the refined tower reflux tank 18, and the finished product receiving tank 19 are respectively connected, and the refined tower steaming pot 16 is connected to the fine tower steam trap valve 20, the fine The tower trap shutoff valve 20 is connected in parallel to the fine tower steam trap bypass valve 21, and the fine tower steamer 16 is connected to the fine tower steam inlet valve 22, The refined tower condenser 17 is connected to the fine tower tail cooler 23, and a fine tower reflux pump 14 is disposed between the fine tower 15 and the refined tower reflux tank 19, and the finished product receiving tank 19 is connected to the finished mixing tank 25.

Example 3

a. Check each equipment, open the main vacuum button of the precision tower system, vacuum valve of each tank, return tank and buffer tank vacuum valve, open the vacuum pump cooling water, open the vacuum pump, open the vacuum pump outlet valve, and slowly open the vacuum pump and inlet valve. When the system pressure reaches -0.09MPa or above, the vacuum pump is stopped, the system is pressure tested, the no-load vacuum is above 0.098Mpa, and the vacuum is reduced by 0.008Mpa within half an hour; b. Open the vacuum pump cooling water valve to adjust the water volume to normal flow, open Vacuum pump outlet valve, drain the liquid in the oil collector, open the vacuum pump inlet vent valve, and then open the vacuum pump. After the vacuum pump is running normally, close the vent valve, open the vacuum pump inlet valve, open the vacuum tower system vacuum button, light tower feed valve 11, when the material 4-amino-trifluorotoluene reaches 1000kg, close the light tower feed valve 11, open the agitator to seal the cooling water, start the stirring motor 10;

d. When the liquid level in the light tower 1 reaches 2/3, the bottom hole of the light tower 1 is recirculated, and when the temperature of the light tower 1 reaches 83 °C, the reflux timing starts, and after 1.5 hours of reflux, the front recovery valve 14 is opened. , produced to the front of the kettle 6;

e. When the mass percentage of dichloro 3,5-dichloro-4-aminobenzotrifluoride is 5%, the temperature change at the top of the light tower 1 is 4 °C, and the feeding to the fine tower system is started. Monochlorinated 3, 5-dichloro-4-aminobenzotrifluoride by 1% by mass;

f. When the liquid level in the tower 2 reaches 1/2, the fine tower trap bypass valve 21 and the refined tower steaming are turned on. The steam inlet valve 22 starts to raise the temperature of the fine tower 15 and raises the temperature to the reflux flow of the bottom tower of the tower 15 , and when the temperature reaches 84 ° C, the reflux time is started, and the reflux time is 1.5 hours;

g. When the temperature at the top of the tower 15 starts to rise and the temperature is at 103 °C, the outlet of the light tower reflux pump 13 is sampled, and the mass percentage of 3, 5-dichloro-4-aminobenzotrifluoride of dichloro is used. At 97%, the finished product receiving tank 19 is started to produce the finished product 3, 5-dichloro-4-aminobenzotrifluoride;

h. Sample the light tower and the fine tower every hour, the mass percentage of the chlorine in the light tower 1 is 1%, and the mass percentage of the 3, 5-dichloro-4-aminobenzotrifluoride in the former tower 15 The content of 5%, the mass percentage of 3, 5-dichloro-4-aminobenzotrifluoride in the refined column 15 is 99.5%, and the yield of the finished 3, 5-dichloro-4-aminobenzotrifluoride is 75 kg per hour. .

The temperature of the light tower 1 and the fine tower 15 rise slowly, the final temperature is 14 CTC, the temperature in the two towers is normally controlled at 125 ° C, the temperature at the top of the tower is between 125 ° C, and the vacuum degree of the entire fine boring system is 0.098 MPa.

a refined column system in a fine process of 3, 5-dichloro-4-aminobenzotrifluoride, the fine column system comprising a fine column 15, a refined column steaming pot 16 and a finished product receiving tank 19, the fine column 15 The light tower system, the refined tower steaming kettle 16, the refined tower condenser 17, the refined tower reflux tank 18, and the finished product receiving tank 19 are respectively connected, and the refined tower steaming pot 16 is connected to the fine tower steam trap valve 20, the fine Tower trap shutoff valve 20 and Connected to the fine tower steam trap bypass valve 21, the fine tower steamer 16 is connected to the fine tower steam inlet valve 22, and the fine tower condenser 17 is connected to the fine tower tail cooler 23, the fine tower 15 and the fine tower A refinery reflux pump 14 is disposed between the reflux tanks 19, and the finished product receiving tank 19 is connected to the finished mixing tank 25.

The raw materials are saved, the final yield is improved, the amount of the residue is greatly reduced, considerable economic benefits are obtained, and the hazardous solid waste treatment and transfer amount is reduced, and good environmental benefits are obtained.

Claims

claims

1. The method for refining 3, 5-dichloro-4-aminotrifluorotoluene, which is characterized by including the following steps: a. Check each equipment, test the system pressure, the no-load vacuum degree is above 0.098Mpa, and the vacuum is completed within half an hour The temperature decrease shall not exceed O. OlMpa;

b. Turn on the vacuum button of the light tower system and the light tower feed valve. When the material 4-amino-trifluorotoluene reaches 1000 parts by mass, close the light tower feed valve, open the mixer seal cooling water, and start the stirring motor; c . When the vacuum degree of the light tower system reaches -0.09MPa, open the light tower steam inlet valve and the light tower trap bypass valve to drain the condensed water, then open the light tower trap stop valve and close the light tower trap bypass valve. ; d. When the liquid level in the light tower reaches 2/3, reflux appears in the sight hole at the bottom of the light tower, and when the temperature of the light tower reaches 78-83 °C, the reflux timing starts, and after refluxing for 1-1.5 hours, the front leakage is started. valve, extracted to the front boiler;

e. When the mass percentage of dichloro 3, 5-dichloro-4-aminotrifluorotoluene reaches 5%, the temperature at the top of the light tower changes by 1-5°C, and the feed to the fine tower system begins;

f. When the liquid level in the polishing tower reaches 1/2, open the bypass valve of the polishing tower trap and the steam inlet valve of the polishing tower, and start to heat up the polishing tower until there is a reflux flow in the bottom sight mirror of the polishing tower, and When the temperature reaches 78-85 °C, the reflux time starts to be counted, and the reflux time is 1-1.5 hours;

g. When the temperature at the top of the fine tower begins to rise and the temperature is between 95-105°C, take a sample of the light tower reflux pump outlet. When the mass percentage of dichloro 3, 5-dichloro-4-aminotrifluorotoluene At 97%, start extracting the finished product 3, 5-dichloro-4-aminotrifluorotoluene from the finished product receiving tank;

h. Sampling the light tower and fine tower every hour, the mass percentage of monochlorine in the light tower is 1% and the mass percentage of 3, 5-dichloro-4-aminotrifluorotoluene before extraction from the fine tower is 5 %, the mass percentage of 3, 5-dichloro-4-aminotrifluorotoluene in the fine tower is 99.5%, and the output of the finished product 3, 5-dichloro-4-aminotrifluorotoluene is 60-80 mass per hour share.

2. The method for refining 3,5-dichloro-4-aminotrifluorotoluene according to claim 1, characterized in that: the temperature of the light tower and the refining tower rises slowly, and the final temperature is 130-140°C. , two towers at medium temperature The temperature is normally controlled between 120-125°C, the tower top temperature is between 110-125°C, and the vacuum degree of the entire fine cooking system is 0.098MPa.

3. The light tower system in the refining method of 3,5-dichloro-4-aminotrifluorotoluene according to claim 1, characterized in that: the light tower system includes a light tower, a front kettle and a light tower. Tower steaming kettle, the light tower is connected to the light tower steaming kettle, the light tower feed pump, the light tower condenser, the light tower reflux tank and the front steaming kettle, and the light tower steaming kettle is connected to the light tower water trap cut-off valve, the light tower steam trap stop valve is connected in parallel with the light tower steam trap bypass valve, the light tower steaming kettle is connected to the light tower steam air inlet valve and the stirring motor, between the light tower and the light tower steaming kettle A light tower feed valve is provided, the light tower condenser is connected to the light tower tail cooler, a light tower reflux pump is provided between the light tower and the light tower reflux tank, and a light tower reflux pump is provided between the light tower and the front kettle. Front production valve.

4. The purification tower system in the purification method of 3,5-dichloro-4-aminotrifluorotoluene according to claim 1 or 3, characterized in that: the purification tower system includes a purification tower, a purification tower distillation The polishing kettle and the finished product receiving tank are connected to the light tower system, the polishing tower steaming kettle, the polishing tower condenser, the polishing tower reflux tank and the finished product receiving tank respectively, and the polishing tower steaming kettle is connected to the polishing tower water trap cut-off valve, the polishing tower steam trap stop valve is connected in parallel with the polishing tower steam trap bypass valve, the polishing tower steam kettle is connected to the polishing tower steam inlet valve, the polishing tower condenser is connected to the polishing tower tail cooler, the polishing tower condenser is connected to the polishing tower tail cooler, A fine tower reflux pump is provided between the tower and the fine tower reflux tank, and the finished product receiving tank is connected to the finished product mixing tank.