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

Abstract

The application provides a constant-temperature difference continuous crystallization control method for p-toluenesulfonamide, which comprises the following steps: S1, preliminary cooling, 75 DEG C decoloring liquid is filtered through activated carbon, and then enters a p-amine refining primary cooling kettle and is cooled through circulating water; S2, secondary cooling, the liquid is further cooled to 38 DEG C through circulating water and then enters a p-amine refining secondary pre-cooling kettle; S3, continuous cooling and crystallization, the decoloring liquid after the preliminary cooling and the secondary cooling enters two parallel p-amine refining deep cooling kettles, i.e., a p-amine refining deep cooling kettle one and a p-amine refining deep cooling kettle two, and is centrifuged in the deep cooling kettles through 7 DEG C cold water to 16 DEG C. The application can achieve the constant-temperature crystallization effect, reduce the labor intensity of operators and greatly improve the crystallization efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of chemical equipment and relates to a p-toluenesulfonamide constant-temperature difference continuous crystallization control method. BACKGROUND

[0002] P-toluenesulfonamide is an organic compound with a molecular formula of C7H9NO2S. It is white flaky or leafy crystals. It is flammable. It is soluble in ethanol and hardly soluble in water and diethyl ether. The melting point is 138.5-139 DEG C, and the hydrate melting point is 105 DEG C [1]. It is used for synthesizing chloramine-T and aminosulfamycin, fluorescent dyes, manufacturing plasticizers, synthetic resins, coatings, disinfectants and wood processing brighteners, etc. With the continuous improvement of China's economy and the national consumption level, the demand for p-toluenesulfonamide is also increasing.

[0003] CN 102584647 A discloses:

[0004] An industrial production method of p-toluenesulfonamide, which adopts a multi-kettle series reaction method, continuously aminates p-toluenesulfonyl chloride and ammonia gas in dichloromethane solvent in a countercurrent absorption mode to generate amide, then removes color through activated carbon, recrystallizes with alcohol, washes with water and dries to obtain qualified products. While realizing continuous production, the method realizes standard discharge of gaseous ammonia in tail gas, reduces environmental pollution and labor intensity. The method adopts solvent instead of water for amination reaction, eliminates hydrolysis side reaction, greatly reduces COD discharge in wastewater while improving reaction conversion rate.

[0005] At present, the production capacity of domestic p-toluenesulfonamide production enterprises is limited to the refining crystallization system, and the traditional single-kettle batch crystallization technology is adopted, which has the problems of poor crystallization control stability, high labor intensity, long cooling time, low efficiency, low production capacity and large cold energy consumption.

[0006] In view of the above, in order to solve the problems in the prior art, the application provides a p-toluenesulfonamide constant-temperature difference continuous crystallization control method which can effectively control the temperature of each kettle, is convenient to operate and can effectively improve the crystallization efficiency. SUMMARY

[0007] The application provides a p-toluenesulfonamide constant-temperature difference continuous crystallization control method which can achieve constant-temperature crystallization effect, reduce the labor intensity of operators and greatly improve the crystallization efficiency.

[0008] The object of the application can be achieved by the following technical scheme:

[0009] A p-toluenesulfonamide constant-temperature difference continuous crystallization control method, comprising:

[0010] S1 preliminary cooling

[0011] 75℃ decoloring solution after activated carbon decoloring filter into the p-amine refining primary cooling kettle, through the cooling water cooling;

[0012] S2 re-cooling

[0013] Re-enter the p-amine refining secondary pre-cooling kettle, through the cooling water cooling to 38℃;

[0014] S3 continuous cooling crystallization

[0015] After the preliminary cooling and re-cooling of the decoloring solution into two parallel p-amine refining deep cooling kettle: p-amine refining deep cooling kettle one, p-amine refining deep cooling kettle two, in the deep cooling kettle, through 7℃ cold water cooling to 16℃, centrifugation;

[0016] Including the following interlocking automatic control steps:

[0017] 1) feed cut-off valve one and p-amine refining primary cooling kettle temperature liquid level and p-amine refining secondary pre-cooling kettle liquid level, temperature interlocking, when the p-amine refining secondary pre-cooling kettle temperature ≤ 38℃ and p-amine refining primary cooling kettle liquid level ≥ 70% and p-amine refining secondary pre-cooling kettle liquid level ≤ 80%, interlocking open feed cut-off valve one, to the p-amine refining secondary pre-cooling kettle feed;

[0018] 2) in the p-amine refining secondary pre-cooling kettle, feed cut-off valve one and p-amine refining primary cooling kettle temperature liquid level and p-amine refining secondary pre-cooling kettle liquid level, temperature interlocking, when the p-amine refining secondary pre-cooling kettle temperature > 45℃ or p-amine refining primary cooling kettle liquid level < 38% or p-amine refining secondary pre-cooling kettle liquid level > 80%, close the feed cut-off valve one;

[0019] 3) in the p-amine refining deep cooling kettle one, feed cut-off valve two and discharge cut-off valve one and p-amine refining deep cooling kettle one liquid level, temperature, discharge cut-off valve two and p-amine refining secondary pre-cooling kettle liquid level interlocking, when the liquid level in the p-amine refining deep cooling kettle one < 80% and p-amine refining deep cooling kettle one temperature < 16℃ and discharge cut-off valve two closed and p-amine refining secondary pre-cooling kettle liquid level ≥ 35%, interlocking open feed cut-off valve two and then open discharge cut-off valve one;

[0020] 4) feed cut-off valve two and discharge cut-off valve one and p-amine refining deep cooling kettle one liquid level, temperature, discharge cut-off valve two and p-amine refining secondary pre-cooling kettle liquid level interlocking, when the p-amine refining deep cooling kettle one liquid level ≥ 80% or p-amine refining deep cooling kettle one temperature ≥ 16℃ or discharge cut-off valve one open or p-amine refining secondary pre-cooling kettle liquid level < 35%, when the feed cut-off valve three is in the closed state, interlocking close discharge cut-off valve one, and open feed cut-off valve three, when the feed cut-off valve three is in the open state, interlocking close feed cut-off valve two.

[0021] As a further improvement of the present solution, the interlocking automatic control step further comprises the following:

[0022] 5) The feed cut-off valve three and the discharge cut-off valve one are interlocked with the liquid level, temperature of the secondary amine refining deep cooling kettle two, the discharge cut-off valve three and the liquid level of the secondary amine refining secondary pre-cooling kettle, when the liquid level of the secondary amine refining deep cooling kettle two is less than 80%, the temperature of the secondary amine refining deep cooling kettle two is less than 16℃, the discharge cut-off valve three is closed and the liquid level of the secondary amine refining secondary pre-cooling kettle is greater than or equal to 35%, the interlocking opens the feed cut-off valve three and then opens the discharge cut-off valve one;

[0023] 6) The feed cut-off valve three and the discharge cut-off valve one are interlocked with the liquid level, temperature of the secondary amine refining deep cooling kettle two, the discharge cut-off valve three and the liquid level of the secondary amine refining secondary pre-cooling kettle, when the liquid level of the secondary amine refining deep cooling kettle two is greater than or equal to 80% or the temperature of the secondary amine refining deep cooling kettle two is greater than or equal to 16℃ or the discharge cut-off valve three is opened or the liquid level of the secondary amine refining secondary pre-cooling kettle is less than 35%, when the feed cut-off valve two is in a closed state, the interlocking closes the discharge cut-off valve one and then opens the feed cut-off valve two, when the feed cut-off valve two is in an opened state, the interlocking closes the feed cut-off valve three. As a further improvement of the present solution, the temperature of the secondary amine refining secondary pre-cooling kettle is controlled at 38℃.

[0024] As a further improvement of the present solution, the crystallization temperature of the deep cooling kettle is controlled at 16℃.

[0025] As a further improvement of the present solution, the temperature of the decoloring liquid is 65-70℃.

[0026] Compared with the prior art, the present application has a reasonable structure, and the continuous crystallization equipment of p-toluene sulfonamide is configured with one primary amine refining pre-cooling kettle, one secondary amine refining secondary pre-cooling kettle and two secondary amine refining deep cooling kettles after the decoloring kettle, liquid level, temperature and feed / discharge cut-off valves are installed in the above kettles, signals are transmitted to the DCS, the primary amine refining pre-cooling kettle and the secondary amine refining secondary pre-cooling kettle are cooled by 20℃ circulating water, and the deep cooling kettles are cooled by 7℃ ice water. The high-temperature decoloring liquid is cooled to the target temperature after entering the deep cooling kettles through the secondary pre-cooling, the liquid level and temperature of each kettle are interlocked with the feed / discharge cut-off valves, the temperature of each kettle is effectively controlled, and the continuous crystallization effect is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present application. DETAILED DESCRIPTION

[0028] The technical solution of the present application is further described below in combination with the embodiments and the drawings.

[0029] As shown in the drawings,

[0030] EMBODIMENT

[0031] The p-toluenesulfonamide constant-temperature differential continuous crystallization device comprises:

[0032] The p-amine refining primary cooling kettle 10 is used for receiving the decoloring liquid after decoloring filtration, and a p-amine refining primary cooling kettle cut-off valve is arranged on the p-amine refining primary cooling kettle 10.

[0033] The p-amine refining secondary pre-cooling kettle 20 is communicated with the p-amine refining primary cooling kettle 10, and a p-amine refining secondary pre-cooling kettle cut-off valve is arranged on the p-amine refining secondary pre-cooling kettle 20.

[0034] The p-amine refining deep cooling kettle one 30 is communicated with the p-amine refining secondary pre-cooling kettle 20, and a p-amine refining deep cooling kettle cut-off valve is arranged on the p-amine refining deep cooling kettle one 30.

[0035] The p-amine refining deep cooling kettle two 40 is communicated with the p-amine refining secondary pre-cooling kettle 20, and the p-amine refining deep cooling kettle two 40 is connected in parallel with the p-amine refining deep cooling kettle one 30.

[0036] As a further preferred embodiment, the temperature of the decoloring liquid is 65-70 DEG C.

[0037] As a further preferred embodiment, a feed cut-off valve one 21 is arranged above the p-amine refining secondary pre-cooling kettle 20, and a discharge cut-off valve one 22 is arranged at the bottom of the p-amine refining secondary pre-cooling kettle 20.

[0038] As a further preferred embodiment, a feed cut-off valve two 31 is arranged above the p-amine refining deep cooling kettle one 30, and a discharge cut-off valve two 32 is arranged at the bottom of the p-amine refining deep cooling kettle one 30.

[0039] As a further preferred embodiment, a feed cut-off valve three 41 is arranged above the p-amine refining deep cooling kettle two 40, and a discharge cut-off valve three 42 is arranged at the bottom of the p-amine refining deep cooling kettle two 40.

[0040] As a further preferred embodiment, the temperature of the p-amine refining secondary pre-cooling kettle 20 into the deep cooling kettle is controlled at 38 DEG C, and the crystallization temperature of the deep cooling kettle is controlled at 16 DEG C.

[0041] At present, the production capacity of the p-toluenesulfonamide production enterprises in China is limited to the refining crystallization system, and the traditional single-kettle intermittent crystallization technology is adopted, so that the crystallization control stability is poor, the operation labor intensity is large, the cooling time is long, the efficiency is low, the production capacity is low, and the cold energy consumption is large.

[0042] Therefore, the p-toluenesulfonamide constant-temperature differential continuous crystallization device which can effectively control the temperature of each kettle and is convenient to operate is designed.

[0043] In the embodiment, the specific operation process is as follows:

[0044] A constant-temperature differential continuous crystallization operation system of p-toluenesulfonamide, which comprises two primary cooling kettles and two deep cooling kettles and related auxiliary instruments: the two primary cooling kettles are a p-amine refining primary cooling kettle 10 and a p-amine refining secondary pre-cooling kettle 20; and the two deep cooling kettles are a p-amine refining deep cooling kettle one 30 and a p-amine refining deep cooling kettle two 40.

[0045] S1 preliminary cooling

[0046] The decoloring liquid at 75℃ is filtered through activated carbon decoloring and then enters the p-amine refining primary cooling kettle 10 and is cooled through circulating water;

[0047] S2 re-cooling

[0048] Then it enters the p-amine refining secondary pre-cooling kettle 20 and is cooled to 38℃ through circulating water;

[0049] S3 continuous cooling crystallization

[0050] The decoloring liquid after preliminary cooling and re-cooling enters two parallel p-amine refining deep cooling kettles: the p-amine refining deep cooling kettle one 30 and the p-amine refining deep cooling kettle two 40, and is cooled to 16℃ through 7℃ cold ice water in the deep cooling kettles and is centrifuged.

[0051] In this embodiment, the continuous crystallization equipment of p-toluenesulfonamide is configured with one p-amine refining primary cooling kettle, one p-amine refining secondary pre-cooling kettle and two p-amine refining deep cooling kettles after the decoloring kettle, and liquid level, temperature and feed and discharge cut-off valves are installed in the above-mentioned crystallization kettles, signals are transmitted to DCS, 20℃ circulating water cooling is adopted for the p-amine refining primary cooling kettle and the p-amine refining secondary pre-cooling kettle, and 7℃ cold ice water cooling is adopted for the deep cooling kettles. The high-temperature decoloring liquid enters the deep cooling kettles after secondary pre-cooling and is cooled to the target temperature, the liquid level and temperature of each kettle are interlocked with the feed and discharge cut-off valves, the temperature of each kettle is effectively controlled, and thus the continuous crystallization effect is achieved.

[0052] The constant-temperature differential continuous crystallization automation technology of p-toluenesulfonamide in the present application comprises the following six sets of interlocked automatic control systems:

[0053] The following interlocked automatic control steps are included:

[0054] 1) The feed cut-off valve one 21 is interlocked with the temperature and liquid level of the p-amine refining primary cooling kettle 10 and the liquid level and temperature of the p-amine refining secondary pre-cooling kettle 20, when the temperature of the p-amine refining secondary pre-cooling kettle 20 is ≤38℃, the liquid level of the p-amine refining primary cooling kettle 10 is ≥70% and the liquid level of the p-amine refining secondary pre-cooling kettle is ≤80%, the interlocking opens the feed cut-off valve one 21 and feeds the p-amine refining secondary pre-cooling kettle;

[0055] 2) The feed cut-off valve one 21 in the primary amine refining secondary pre-cooling kettle 20 is interlocked with the temperature and level of the primary amine refining primary cooling kettle 10 and the level and temperature of the primary amine refining secondary pre-cooling kettle 20. When the temperature of the primary amine refining secondary pre-cooling kettle 20 > 45℃ or the level of the primary amine refining primary cooling kettle 10 < 38% or the level of the primary amine refining secondary pre-cooling kettle 20 > 80%, the feed cut-off valve one 21 is closed.

[0056] 3) The feed cut-off valve two 31 and the discharge cut-off valve one 22 in the primary amine refining deep cooling kettle one 30 are interlocked with the level and temperature of the primary amine refining deep cooling kettle one 30, the discharge cut-off valve two 32 and the level of the primary amine refining secondary pre-cooling kettle 20. When the level in the primary amine refining deep cooling kettle one 30 < 80% and the temperature of the primary amine refining deep cooling kettle one 30 < 16℃ and the discharge cut-off valve two 32 is closed and the level of the primary amine refining secondary pre-cooling kettle 20 ≥ 35%, the interlocking opens the feed cut-off valve two 31 and then opens the discharge cut-off valve one 22.

[0057] 4) The feed cut-off valve two 31 and the discharge cut-off valve one 22 are interlocked with the level and temperature of the primary amine refining deep cooling kettle one 30, the discharge cut-off valve two 32 and the level of the primary amine refining secondary pre-cooling kettle 20. When the level of the primary amine refining deep cooling kettle one 30 ≥ 80% or the temperature of the primary amine refining deep cooling kettle one 30 ≥ 16℃ or the discharge cut-off valve one 22 is opened or the level of the primary amine refining secondary pre-cooling kettle 20 < 35%, when the feed cut-off valve three 41 is in the closed state, the interlocking closes the discharge cut-off valve one 22 and then opens the feed cut-off valve three 41. When the feed cut-off valve three 41 is in the open state, the interlocking closes the feed cut-off valve two 31.

[0058] 5) The feed cut-off valve three 41 and the discharge cut-off valve one 22 are interlocked with the level and temperature of the primary amine refining deep cooling kettle two 40, the discharge cut-off valve three 42 and the level of the primary amine refining secondary pre-cooling kettle 20. When the level of the primary amine refining deep cooling kettle two 40 < 80% and the temperature of the primary amine refining deep cooling kettle two 40 < 16℃ and the discharge cut-off valve three 42 is closed and the level of the primary amine refining secondary pre-cooling kettle 20 ≥ 35%, the interlocking opens the feed cut-off valve three 41 and then opens the discharge cut-off valve one 22.

[0059] 6) The feed cut-off valve three 41 and the discharge cut-off valve one 22 are interlocked with the level and temperature of the primary amine refining deep cooling kettle two 40, the discharge cut-off valve three 42 and the level of the primary amine refining secondary pre-cooling kettle 20. When the level of the primary amine refining deep cooling kettle two 40 ≥ 80% or the temperature of the primary amine refining deep cooling kettle two 40 ≥ 16℃ or the discharge cut-off valve three 42 is opened or the level of the primary amine refining secondary pre-cooling kettle 20 < 35%; when the feed cut-off valve two 31 is in the closed state, the interlocking closes the discharge cut-off valve one 22 and then opens the feed cut-off valve two 31. When the feed cut-off valve two 31 is in the open state, the interlocking closes the feed cut-off valve three 41.

[0060] In the technical scheme of the present application, the automatic instrument control system is equipped for the constant-temperature continuous crystallization system, the temperature of each crystallization kettle is effectively controlled, and continuous production is achieved. A constant-temperature difference continuous crystallization technology for p-toluenesulfonamide is proposed, the temperature of the secondary pre-cooling kettle and the deep cooling kettle can be controlled at 38 DEG C and 16 DEG C respectively, the constant-temperature crystallization effect is achieved, the labor intensity of the operator is reduced, the crystallization efficiency can be greatly improved, before the temperature of each kettle is controlled in the continuous crystallization, the initial cooling kettle R0628 is dissolved in the kettle wall every day, and the production capacity is limited. After the scheme of the embodiment is implemented, R0628 needs to be dissolved in the kettle wall only once every 5-7 days, the daily output is improved by 8-10%, and the production capacity is improved.

[0061] The preferred embodiments described herein are merely preferred embodiments of the present application, but the protection scope of the present application is not limited thereto. Modifications or supplements to the described specific embodiments or the use of similar ways of replacement made by those skilled in the art to which the present application belongs shall be covered within the protection scope of the present application.

Claims

1. A constant-temperature difference continuous crystallization control method for p-toluenesulfonamide, characterized by comprising: S1 preliminary cooling 75℃ decolorizing solution is filtered through activated carbon decolorizing filter and then enters p-amine refining primary cooling kettle (10) and is cooled by circulating water; S2 secondary cooling Then enters p-amine refining secondary pre-cooling kettle (20) and is cooled to 38℃ by circulating water; S3 continuous cooling crystallization The decolorizing solution after preliminary cooling and secondary cooling enters two parallel p-amine refining deep cooling kettles: p-amine refining deep cooling kettle one (30) and p-amine refining deep cooling kettle two (40), and is cooled to 16℃ by 7℃ cold ice water in the kettles and is centrifuged; The method comprises the following interlocking automatic control steps: 1) Feeding cut-off valve one (21) is interlocked with the temperature and liquid level of p-amine refining primary cooling kettle (10) and the liquid level and temperature of p-amine refining secondary pre-cooling kettle (20), when the temperature of p-amine refining secondary pre-cooling kettle (20) is ≤38℃, the liquid level of p-amine refining primary cooling kettle (10) is ≥70% and the liquid level of p-amine refining secondary pre-cooling kettle is ≤80%, the interlocking opens feeding cut-off valve one (21) to feed p-amine refining secondary pre-cooling kettle; 2) In p-amine refining secondary pre-cooling kettle (20), feeding cut-off valve one (21) is interlocked with the temperature and liquid level of p-amine refining primary cooling kettle (10) and the liquid level and temperature of p-amine refining secondary pre-cooling kettle (20), when the temperature of p-amine refining secondary pre-cooling kettle (20) is >45℃ or the liquid level of p-amine refining primary cooling kettle (10) is <38% or the liquid level of p-amine refining secondary pre-cooling kettle (20) is >80%, feeding cut-off valve one (21) is closed; 3) In p-amine refining deep cooling kettle one (30), feeding cut-off valve two (31) and discharging cut-off valve one (22) are interlocked with the liquid level and temperature of p-amine refining deep cooling kettle one (30), discharging cut-off valve two (32) and the liquid level of p-amine refining secondary pre-cooling kettle (20), when the liquid level in p-amine refining deep cooling kettle one (30) is <80%, the temperature of p-amine refining deep cooling kettle one (30) is <16℃, discharging cut-off valve two (32) is closed and the liquid level of p-amine refining secondary pre-cooling kettle (20) is ≥35%, the interlocking opens feeding cut-off valve two (31) and then opens discharging cut-off valve one (22); 4) Feeding cut-off valve two (31) and discharging cut-off valve one (22) are interlocked with the liquid level and temperature of p-amine refining deep cooling kettle one (30), discharging cut-off valve two (32) and the liquid level of p-amine refining secondary pre-cooling kettle (20), when the liquid level of p-amine refining deep cooling kettle one (30) is ≥80% or the temperature of p-amine refining deep cooling kettle one (30) is ≥16℃ or discharging cut-off valve one (22) is opened or the liquid level of p-amine refining secondary pre-cooling kettle (20) is <35%, when feeding cut-off valve three (41) is in the closed state, discharging cut-off valve one (22) is closed and feeding cut-off valve three (41) is opened, when feeding cut-off valve three (41) is in the opened state, feeding cut-off valve two (31) is closed. The interlocking automatic control steps further comprise the following:

2. The constant temperature difference continuous crystallization control method of p-toluenesulfonamide according to claim 1, characterized by, ​ 5) Feed cut-off valve three (41) and discharge cut-off valve one (22) are interlocked with the liquid level of the secondary amine refining deep cooling kettle two (40), the temperature of the secondary amine refining deep cooling kettle two (40), the discharge cut-off valve three (42) and the liquid level of the secondary amine refining secondary pre-cooling kettle (20), when the liquid level of the secondary amine refining deep cooling kettle two (40) is <80%, the temperature of the secondary amine refining deep cooling kettle two (40) is <16℃, the discharge cut-off valve three (42) is closed and the liquid level of the secondary amine refining secondary pre-cooling kettle (20) is ≥35%, the interlock opens the feed cut-off valve three (41) and then opens the discharge cut-off valve one (22); 6) Feed cut-off valve three (41) and discharge cut-off valve one (22) are interlocked with the liquid level of the secondary amine refining deep cooling kettle two (40), the temperature of the secondary amine refining deep cooling kettle two (40), the discharge cut-off valve three (42) and the liquid level of the secondary amine refining secondary pre-cooling kettle (20), when the liquid level of the secondary amine refining deep cooling kettle two (40) is ≥80% or the temperature of the secondary amine refining deep cooling kettle two (40) is ≥16℃ or the discharge cut-off valve three (42) is opened or the liquid level of the secondary amine refining secondary pre-cooling kettle (20) is <35%, when the feed cut-off valve two (31) is in the closed state, the interlock closes the discharge cut-off valve one (22) and then opens the feed cut-off valve two (31), when the feed cut-off valve two (31) is in the open state, the interlock closes the feed cut-off valve three (41).

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