CN116059678A - A kind of p-toluenesulfonamide constant temperature difference continuous crystallization control method - Google Patents

Abstract

The invention provides a constant temperature difference continuous crystallization control method for p-toluenesulfonamide, which includes: S1 preliminary cooling, 75 ° C decolorization liquid is decolorized by activated carbon and filtered by activated carbon, then enters the p-amine refining primary cooling kettle, and is cooled by circulating water; S2 is cooled again, and then Enter the secondary pre-cooling tank for refining amine, and cool down to 38°C through circulating water; S3 continuously cools down and crystallizes, and the decolorized liquid after initial cooling and cooling again enters two parallel deep-cooling tanks for refining amine: deep cooling for refining amine Kettle 1, p-amine refining deep-cooled kettle 2, in the deep-cooled kettle, cool down to 16°C with 7°C cold water and centrifuge. The invention can achieve constant temperature crystallization effect, reduce the labor intensity of operators, and greatly improve the crystallization efficiency.

Description

A kind of p-toluenesulfonamide constant temperature difference continuous crystallization control method

technical field

The invention belongs to the technical field of chemical equipment and relates to a constant temperature difference continuous crystallization control method for p-toluenesulfonamide.

Background technique

p-Toluenesulfonamide) is an organic compound with the molecular formula C7H9NO2S. It is white flake or leaf crystal. flammable. Soluble in ethanol, insoluble in water and ether. The melting point is 138.5～139°C, and the melting point of hydrate is 105°C[1]. Used in the synthesis of chloramine-T and chloramphenicol, fluorescent dyes, plasticizers, synthetic resins, paints, disinfectants and wood processing brighteners. With the continuous improvement of my country's economy and national consumption level, the demand for p-toluenesulfonamide is also increasing.

CN102584647A discloses:

A kind of industrialized production method of p-toluenesulfonamide adopts the method of multi-pot series reaction, carries out continuous amination reaction of p-toluenesulfonyl chloride and ammonia in a methylene chloride solvent in a countercurrent absorption mode to generate amide, and then decolorizes by activated carbon, Alcohol recrystallization, washing and drying to obtain qualified products. While realizing continuous production, the discharge of ammonia in the tail gas reaches the standard, which reduces environmental pollution and labor intensity. Using a solvent instead of water for the amination reaction eliminates side reactions of hydrolysis and greatly reduces COD emissions in wastewater while increasing the conversion rate of the reaction.

At present, the production capacity of domestic p-toluenesulfonamide production enterprises is limited to the refined crystallization system. The traditional single-pot batch crystallization technology has poor crystallization control stability, high labor intensity, long cooling time, low efficiency, low production capacity, and large cooling energy consumption. And other issues.

In summary, in order to solve the deficiencies in the prior art, the present invention designs a constant temperature difference continuous crystallization control method for p-toluenesulfonamide that can effectively control the temperature of each kettle, facilitate operation, and effectively improve crystallization efficiency.

Contents of the invention

In order to solve the problems existing in the prior art, the present invention provides a p-toluenesulfonamide constant temperature difference continuous crystallization control method that can achieve constant temperature crystallization effect, reduce the labor intensity of operators, and greatly improve the crystallization efficiency.

The purpose of the present invention can be achieved through the following technical solutions:

A constant temperature difference continuous crystallization control method for p-toluenesulfonamide, comprising:

S1 initial cooling

The decolorization liquid at 75°C is decolorized by activated carbon and filtered by activated carbon, then enters the primary cooling tank for refining amine, and cools down through circulating water;

S2 cools down again

Then enter the secondary pre-cooling tank for amine refining, and cool down to 38°C through circulating water;

S3 continuous cooling crystallization

After initial cooling and cooling down again, the decolorized liquid enters two parallel amine refining cryogenic kettles: amine refining cryogenic kettle 1 and amine refining cryogenic kettle 2. In the cryogenic kettle, 7°C cold ice water is passed through Cool down to 16°C and centrifuge.

As a further improvement of this program, the following interlocking automatic control steps are included:

1) The cut-off valve of the secondary pre-cooling tank for refining amine is interlocked with the temperature and liquid level of the primary cooling tank for refining amine and the liquid level and temperature of the secondary pre-cooling tank for refining amine. When the temperature of the secondary pre-cooling tank for refining amine When ≤38℃ and the liquid level of the primary cooling tank for refining amines is ≥70% and the liquid level of the secondary pre-cooling tank for refining amines is ≤80%, open the shut-off valve of the secondary cooling tank for refining Stage pre-cooling kettle feed;

2) In the secondary pre-cooling tank for refining amines 20), the cut-off valve of the secondary pre-cooling tank for refining amines is interlocked with the temperature and liquid level of the primary cooling tank for refining amines and the liquid level and temperature of the secondary pre-cooling tank for refining amines, When the temperature of the secondary pre-cooler for refining amines > 45°C or the liquid level of the primary cooling tank for refining amines < 38% or the liquid level of the secondary pre-cooling tank for refining amines > 80%, close the secondary pre-cooling tank for refining amines Feed switching valve;

3) In the deep-cooling kettle 30 for refining amine, the cut-off valve of the deep-cooling kettle for refining amine and the bottom cut-off valve for the secondary pre-cooling kettle for refining amine are connected to the liquid level, temperature, and bottom of the deep-cooling kettle for refining amine. The shut-off valve and the liquid level interlocking of the secondary pre-cooling tank for refining amines, when the liquid level in the cooling tank for refining amines < 80% and the temperature of 30% of the cooling tank for refining amines < 16°C and the bottom of the cooling tank for refining amines When the cut-off valve is closed and the liquid level of the secondary pre-cooling kettle for amine refining is ≥35%, open the cut-off valve of the feed valve of the deep-cooling kettle for refining amine through interlocking, and then open the cut-off valve at the bottom of the secondary pre-cooling kettle for refining amine;

4) The cut-off valve of the deep-cooling kettle for refining amine and the bottom shut-off valve of the secondary pre-cooling kettle for refining amine are interlocked with the liquid level, temperature, bottom shut-off valve of the deep-cooling kettle for refining amine and the liquid level of the secondary pre-cooling kettle for refining amine , when the liquid level of the amine refining cryogenic tank is ≥80% or the temperature is ≥16°C or the bottom cut-off valve is opened or the liquid level of the amine refining secondary pre-cooling tank is less than 35%, when it is in the closed state, the interlock is closed for the amine refining The cut-off valve at the bottom of the secondary pre-cooling kettle is opened, and then the feed cut-off valve is opened. When it is in the open state, the feed cut-off valve is interlocked and closed.

5) The shut-off valve of the deep-cooling kettle for amine refining and the bottom shut-off valve of the secondary pre-cooling kettle for refining amine are interlocked with the liquid level, temperature, bottom shut-off valve of the deep-cooling kettle for refining amine and the liquid level of the secondary pre-cooling kettle for refining amine , when the liquid level of the amine refining cryogenic kettle 2 is less than 80% and the temperature of the amine refining cryogenic kettle 2 is less than 16°C and the cut-off valve at the bottom of the amine refining cryogenic kettle 2 is closed and the liquid level of the amine refining secondary precooling kettle is ≥ When it is 35%, open the second feed valve of the amine refining deep-cooling kettle interlockedly, and then open the bottom cut-off valve of the amine refining secondary precooling kettle.

6) The shut-off valve of the deep-cooling kettle for refining amine and the bottom shut-off valve of the secondary pre-cooling kettle for refining amine are interlocked with the liquid level, temperature, bottom shut-off valve of the deep-cooling kettle for refining amine and the liquid level of the secondary pre-cooling kettle for refining amine , when the liquid level of the amine refining cryogenic tank is ≥80% or the temperature of the amine refining cryogenic tank is ≥16°C or the bottom cut-off valve is opened or the liquid level is <35%; when it is closed, the interlocking will close the second stage of the amine refining The cut-off valve at the bottom of the pre-cooling kettle, and then open the feed cut-off valve of the amine refining cryogenic kettle, when the feed shut-off valve of the amine refining cryogenic kettle is open, the interlocking shuts off the feed cut-off of the amine refining cryogenic kettle 2 valve.

As a further improvement of this scheme, the temperature of the amine refining secondary pre-cooling tank entering the deep cooling tank is controlled at 38°C.

As a further improvement of this scheme, the crystallization temperature of the cryogenic tank is controlled at 16°C.

As a further improvement of this solution, the temperature of the decolorizing solution is 65-70°C.

Compared with the prior art, the structure design of the present invention is reasonable, and the p-toluenesulfonamide continuous crystallization equipment is equipped with a p-amine refining primary cooling tank, a p-amine refining secondary pre-cooling tank and 2 p-amine refining tanks behind the decolorization tank. Amine refining deep-cooling kettle, and then by installing liquid level, temperature and inlet and outlet cut-off valves in the crystallization kettle, the signal is transmitted to DCS, and the primary cooling kettle for amine refining and the secondary pre-cooling kettle for amine refining are cooled by 20°C circulating water , The cryogenic kettle was cooled with 7°C ice water. The high-temperature decolorizing liquid enters the deep-cooling tank after secondary pre-cooling and cools down to the target temperature. The liquid level temperature of each tank is interlocked with the switching valve of the inlet and outlet materials to effectively control the temperature of each tank, so as to achieve continuous crystallization effect.

Description of drawings

Fig. 1 is a structural schematic diagram of a constant temperature difference continuous crystallization device for toluenesulfonamide of the present invention.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

as the picture shows,

Example

The p-toluenesulfonamide constant temperature difference continuous crystallization device includes:

The primary cooling kettle 10 for refining amines is used to receive the decolorized liquid through decolorization and filtration, and the primary cooling kettle 10 for refining amines is provided with a cut-off valve for the primary cooling kettles for refining amines;

The secondary pre-cooling kettle 20 for refining amines, the secondary pre-cooling kettle 20 for refining amines is connected to the primary cooling kettle 10 for refining amines, and the secondary pre-cooling kettle 20 for refining amines is provided with a cut-off function for the secondary pre-cooling kettles for refining amines. valve;

Refining amine cryogenic kettle 1 30, amine refining cryogenic kettle 1 30 communicates with amine refining secondary pre-cooling kettle 20, amine refining cryogenic kettle 1 30 is provided with amine refining cryogenic kettle 1 cut-off valve;

P-amine refining deep cooling kettle two 40, para-amine refining deep cooling kettle two 40 communicate with p-amine refining secondary pre-cooling kettle 20, and p-amine refining deep cooling kettle two 40 and p-amine refining deep cooling kettle one 30 are connected in parallel.

As a further preferred embodiment, the temperature of the decolorizing solution is 65-70°C.

As a further preferred embodiment, a feed cut-off valve 21 for the secondary pre-cooling kettle 20 for refining amines is provided above the secondary pre-cooling kettle 20 for refining amines, and a secondary pre-cooling kettle for refining amines is installed at the bottom of the secondary pre-cooling kettle 20 for refining amines. Stage pre-cooling kettle discharge cut-off valve 22.

As a further preferred embodiment, a feed cut-off valve 31 for the amine refining cryogenic kettle 30 is provided above the amine refining cryogenic kettle 30, and a amine refining cryogenic kettle 1 is provided at the bottom of the amine refining cryogenic kettle 30. Discharge cut-off valve 32.

As a further preferred embodiment, a feed cut-off valve 41 for the second amine refining cryogenic kettle 40 is arranged above the amine refining cryogenic kettle 40, and a second amine refining cryogenic kettle 40 is provided at the bottom of the amine refining cryogenic kettle 2 Discharge cut-off valve 42.

As a further preferred embodiment, the temperature of the amine refining secondary pre-cooling tank 20 entering the deep cooling tank is controlled at 38°C, and the crystallization temperature of the deep cooling tank is controlled at 16°C.

At present, the production capacity of domestic p-toluenesulfonamide production enterprises is limited to the refined crystallization system. The traditional single-pot batch crystallization technology has poor crystallization control stability, high labor intensity, long cooling time, low efficiency, low production capacity, and large cooling energy consumption. And other issues.

For this reason, the present invention designs a p-toluenesulfonamide constant temperature difference continuous crystallization device that can effectively control the temperature of each kettle and is convenient to operate.

In this embodiment, the specific operation process is as follows:

A p-toluenesulfonamide constant temperature difference continuous crystallization operating system, the crystallization operating system includes 2 primary cooling kettles and 2 deep cooling kettles and related auxiliary instruments: the 2 primary cooling kettles are p-amine refining primary cooling kettles 10, Refined para-amine secondary pre-cooling kettle 20; 2 deep-cooled kettles are amine-purified deep-cooled kettle 1 30, para-amine refined deep-cooled kettle 2 40;

S1 initial cooling

The decolorized liquid at 75°C is decolorized by activated carbon and filtered by activated carbon, then enters the primary cooling tank 10 for refining amine, and is cooled by circulating water;

S2 cools down again

Then enter the secondary pre-cooling kettle 20 for refining amine, and cool down to 38° C. through circulating water;

S3 continuous cooling crystallization

After preliminary cooling and cooling down again, the decolorized liquid enters two parallel amine refining cryogenic kettles: amine refining cryogenic kettle one 30, and amine refining cryogenic kettle two 40, in the cryogenic kettle, through 7 ℃ cooling Cool down to 16°C in ice water and centrifuge.

In this embodiment, the p-toluenesulfonamide continuous crystallization equipment is equipped with 1 p-amine refining primary cooling kettle, 1 p-amine refining secondary pre-cooling kettle and 2 p-amine refining deep cooling kettles after the decolorization kettle, and then passes The liquid level, temperature and inlet and outlet cut-off valves are installed in the above crystallization kettles, and the signals are transmitted to the DCS. Cool with ice water. The high-temperature decolorizing liquid enters the deep-cooling tank after secondary pre-cooling and cools down to the target temperature. The liquid level temperature of each tank is interlocked with the switching valve of the inlet and outlet materials to effectively control the temperature of each tank, so as to achieve continuous crystallization effect.

The p-toluenesulfonamide constant temperature difference continuous crystallization automation technology of the present invention includes the following 6 sets of interlocking automatic control systems:

1) The cut-off valve 21 of the secondary pre-cooling tank for refining amine is interlocked with the temperature and liquid level of the primary cooling tank 10 for refining amine and the liquid level and temperature of the secondary pre-cooling tank 20 for refining amine. When the temperature of the cold kettle 20 is ≤38°C and the liquid level of the primary cooling kettle 10 for amine refining is ≥70% and the liquid level of the secondary pre-cooling kettle for amine refining is ≤80%, open the shut-off valve 21 of the secondary pre-cooling kettle for amine refining , feeding to the secondary pre-cooling tank for p-amine refining;

2) In the secondary pre-cooling kettle 20 for refining amine, the cut-off valve 21 of the secondary pre-cooling kettle for refining amine is connected to the temperature liquid level of the primary cooling kettle 10 for refining amine and the liquid level and temperature of the secondary pre-cooling kettle 20 for refining amine. Lock, when the temperature of the amine refining secondary pre-cooling kettle 20 is > 45°C or the amine refining primary cooling kettle 10 liquid level is < 38% or the amine refining secondary pre-cooling kettle 20 liquid level is > 80%, close the amine refining Secondary pre-cooling kettle feed switching valve 21;

3) In the amine refining cryogenic kettle 30, the amine refining cryogenic kettle cut-off valve 31 and the amine refining secondary pre-cooling kettle 20 bottom cut-off valve 22 and the amine refining cryogenic kettle 30 liquid level, temperature, and amine refining The shut-off valve 32 at the bottom of the deep-cooling kettle and the liquid level interlocking of the secondary pre-cooling kettle 20 for refining amine, when the liquid level in the deep-cooling kettle 30 for refining amine<80% and the temperature of the deep-cooling kettle 30 for refining amine<16°C And when the shut-off valve 32 at the bottom of the amine refining cryogenic kettle is closed and the liquid level of the amine refining secondary pre-cooling kettle 20 is ≥ 35%, the interlock opens the amine refining cryogenic kettle feed valve cut-off valve 31 and then opens the amine refining Cut-off valve 22 at the bottom of the secondary pre-cooler;

4) The shut-off valve 31 of the deep-cooling kettle for amine refining and the bottom shut-off valve 22 of the secondary pre-cooling kettle 20 for refining amine and the liquid level, temperature, and bottom shut-off valve 32 of the cryogenic kettle 30 for refining amine and the secondary pre-cooling for refining amine The liquid level of the 20 tank is interlocked. When the liquid level of the amine refining deep-cooling tank 30 is ≥ 80% or the temperature of the 30 is ≥ 16°C or the bottom cut-off valve 22 is opened or the liquid level of the amine refining secondary pre-cooling tank 20 is < 35%, when 41 is in the closed state, and the interlock closes the shut-off valve 31 at the bottom of the secondary pre-cooling kettle 20 for amine refining, and then opens the second feed cut-off valve 41 of the deep-cooling kettle for amine refining, and when the feed shut-off valve 41 is open, the interlock closes Enter the feed cut-off valve 31 of the amine refining cryogenic kettle.

5) The cut-off valve of the deep-cooling kettle for refining amine and the bottom shut-off valve 22 of the secondary pre-cooling kettle for refining amine and the liquid level, temperature, and bottom shut-off valve 42 of the deep-cooling kettle 40 for refining amine and the secondary pre-cooling kettle 20 for refining amine Liquid level interlocking, when the liquid level of the amine refining cryogenic kettle 2 40 is less than 80% and the temperature of the amine refining cryogenic kettle 2 40 is less than 16°C and the bottom cut-off valve 42 of the amine refining cryogenic kettle 2 is closed and the amine refining cryogenic kettle 2 When the liquid level of the first-stage pre-cooling kettle 20 is ≥ 35%, the second feed valve 41 of the amine refining cryogenic kettle is opened interlockingly, and then the bottom cut-off valve 22 of the second-stage pre-cooling kettle for amine refining is opened.

6) The shut-off valve 41 of the deep-cooling kettle for amine refining and the bottom shut-off valve 22 of the secondary pre-cooling kettle 20 for refining amine and the liquid level, temperature, and bottom shut-off valve 42 of the cryogenic kettle 40 for refining amine and the secondary pre-cooling for refining amine Liquid level interlock of kettle 20, when the liquid level of amine refining cryogenic kettle 40 is ≥80% or the temperature of amine refining cryogenic kettle 40 is ≥16°C or the bottom cut-off valve 42 is opened or the liquid level of amine refining secondary precooling kettle is < 35%; when the feed cut-off valve 31 of the refining cryogenic kettle for amine is closed, the interlock closes the cut-off valve at the bottom of the secondary precooling kettle for refining amine, and then opens the feed cut-off valve 31 for the refining cryogenic kettle for amine, when The feed cut-off valve 31 of the amine refining cryogenic kettle is in an open state, and the feed shutoff valve 41 of the amine refining cryogenic kettle 2 is interlocked and closed.

In the technical solution of the present invention, the constant temperature continuous crystallization system is equipped with an automatic instrument control system to effectively control the temperature of each crystallization tank and achieve continuous production. A constant temperature difference continuous crystallization technology for p-toluenesulfonamide is proposed, which can control the temperature of the secondary pre-cooler into the deep-cooler at 38°C, and control the crystallization temperature of the deep-cooler at 16°C, achieving constant temperature crystallization effect and reducing operation The labor intensity of personnel is reduced, and the efficiency of crystallization can also be greatly improved. Before continuous crystallization controls the temperature of each kettle: the initial cooling kettle R0628 dissolves the wall of the kettle every day, limiting the production capacity. After the implementation of the scheme of this embodiment: R0628 only needs to dissolve the pot wall once in 5-7 days, so that the daily output is increased by 8-10%, and the production capacity is increased.

What is described herein is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Modifications or supplements to the described specific embodiments by those skilled in the art to which the present invention pertains or replacements in similar ways shall fall within the protection scope of the present invention.

Claims (5)

1. a p-toluenesulfonamide constant temperature difference continuous crystallization control method is characterized in that, include: S1 initial cooling The decolorized liquid at 75°C is decolorized by activated carbon and filtered by activated carbon, and then enters the primary cooling kettle (10) for refining amine, and is cooled by circulating water; S2 cools down again Then enter the secondary pre-cooling kettle (20) for amine refining, and cool down to 38°C by circulating water; S3 continuous cooling crystallization The decolorizing liquid after initial cooling and cooling down again enters 2 parallel amine refining cryogenic kettles: the amine refining cryogenic kettle one (30), the amine refining cryogenic kettle two (40), in the cryogenic kettle, Cool down to 16°C with 7°C cold ice water and centrifuge. 2. a kind of p-toluenesulfonamide constant temperature difference continuous crystallization control method according to claim 1, is characterized in that, comprises following interlocking automatic control step: 1) The cut-off valve (21) of the secondary pre-cooling tank for refining amines is interlocked with the temperature and liquid level of the primary cooling tank for refining amines (10) and the liquid level and temperature of the secondary pre-cooling tank for refining amines (20). When the temperature of the secondary pre-cooling tank (20) for refining amines is ≤38°C and the liquid level of the primary cooling tank (10) for refining amines is ≥70% and the liquid level of the secondary pre-cooling tanks for refining amines is ≤80%, the interlock opens the The shut-off valve (21) of the secondary pre-cooling kettle for refining amine is used to feed the secondary pre-cooling kettle for refining amine; 2) In the secondary pre-cooler for refining amine 20), the shut-off valve (21) of the secondary pre-cooling tank for refining amine and the temperature and liquid level of the primary cooling tank for refining amine (10) and the secondary pre-cooling tank for refining amine ( 20) Liquid level and temperature interlocking, when the temperature of the amine refining secondary pre-cooling kettle (20) is >45°C or the liquid level of the amine refining primary cooling kettle (10) is <38% or the amine refining secondary precooling kettle ( 20) When the liquid level > 80%, close the feed switching valve (21) of the secondary pre-cooling tank for amine refining; 3) In the amine refining cryogenic kettle 30, the amine refining cryogenic kettle cut-off valve (31) and the amine refining secondary pre-cooling kettle (20) bottom shut-off valve (22) and the amine refining cryogenic kettle (30) Liquid level, temperature, the bottom cut-off valve (32) of the deep-cooling kettle for refining amine and the liquid level interlocking of the secondary pre-cooling kettle (20) for refining amine, when the liquid level in the deep-cooling kettle for refining amine (30) <80 % and the amine refining cryogenic kettle 30 temperature < 16 ℃ and the amine refining cryogenic kettle bottom cut-off valve (32) is closed and the amine refining secondary precooling kettle (20) liquid level ≥ 35%, the interlock is opened to Open the cut-off valve (22) at the bottom of the amine refining secondary pre-cooling kettle after the feed valve cut-off valve (31) of the amine refining deep-cooling kettle; 4) The cut-off valve (31) of the cryogenic kettle for refining amine and the cut-off valve (22) at the bottom of the secondary pre-cooling kettle (20) for refining amine and the liquid level, temperature and bottom cut-off valve of the cryogenic kettle (30) for refining amine ( 32) and the liquid level interlocking of the secondary pre-cooling kettle (20) for refining amine, when the liquid level of the deep-cooling kettle (30) for refining amine is ≥80% or the temperature of (30) is ≥16°C or the bottom cut-off valve (22) is opened Or when the liquid level of the secondary pre-cooling kettle (20) for refining amines is less than 35%, when (41) is in a closed state, the interlock closes the shut-off valve (31) at the bottom of the secondary pre-cooling kettle (20) for refining amines, and then opens (40) feed cut-off valve (41), when (41) is open state, interlock closes and enters (30) feed cut-off valve (31). 5) The cut-off valve (41) of the deep-cooling kettle (40) for refining amine and the bottom shut-off valve (22) of the secondary pre-cooling kettle (20) for refining amine and the liquid level, temperature and bottom of the deep-cooling kettle (40) for refining amine The shut-off valve (42) and the liquid level interlocking of the secondary pre-cooling kettle (20) for amine refining, when the liquid level of the second (40) of the refining cryogenic kettle (40) for amines <80% and the temperature of the second (40) refining cooling kettle for amine When <16°C and the second bottom cut-off valve (42) of the amine refining cryogenic kettle is closed and the liquid level of the amine refining secondary precooling kettle (20) is ≥35%, the interlock opens the amine refining cryogenic kettle second feed valve (41) and then open the shut-off valve (22) at the bottom of the secondary pre-cooling tank for amine refining. 6) The cut-off valve (41) of the cryogenic kettle for refining amine and the bottom cut-off valve (22) of the secondary pre-cooling kettle (20) for refining amine and the liquid level, temperature and bottom cut-off valve of the cryogenic kettle (40) for refining amine ( 42) and the liquid level interlocking of the secondary pre-cooling kettle (20) for refining amine, when the liquid level of the deep cooling kettle (40) for refining amine is ≥80% or the temperature of the deep cooling kettle (40) for refining amine is ≥16°C or the bottom When the shut-off valve (42) is opened or the liquid level of (20) is <35%; when (31) is in the closed state, the interlock closes the shut-off valve at the bottom of the amine refining secondary pre-cooling kettle, and then opens the amine refining cryogenic kettle to feed Cut-off valve (31), when the feed cut-off valve (31) of the amine refining cryogenic kettle is open, the interlocking closure enters the feed cut-off valve (41) of the amine refining cryogenic kettle two. 3. a kind of p-toluenesulfonamide constant temperature difference continuous crystallization control method according to claim 2, is characterized in that, the temperature of the amine refining secondary precooling kettle (20) entering the deep cooling kettle is controlled at 38 ℃. 4. A method for controlling the constant temperature difference continuous crystallization of p-toluenesulfonamide according to claim 1, characterized in that the crystallization temperature of the cryogenic tank is controlled at 16°C. 5. A method for controlling continuous crystallization of p-toluenesulfonamide with constant temperature difference according to claim 4, characterized in that the temperature of the decolorizing solution is 65-70°C.

Images