Fractional crystallization apparatus for di-t-butyl peroxide

Abstract

The utility model belongs to the production technology field of diisopropyl peroxide, specifically relates to a diisopropyl peroxide fractional crystallization device, the diisopropyl peroxide fractional crystallization device, including rectifying tower, rectifying tower is connected with filter through the delivery pump, filter is connected with pretreatment tank, and the bottom of pretreatment tank is connected with primary crystallization tank through pre-cooler, and primary crystallization tank is connected with primary centrifuge, secondary crystallization tank, secondary centrifuge and product tank in proper order. The diisopropyl peroxide fractional crystallization device of the utility model, the large particle coarse crystal of primary crystallization is removed, and secondary crystallization is dissolved and recrystallized to further purify, which improves the product purity; the fine crystal obtained by mother liquor filter is used to replace the seed crystal to realize induced crystallization, which ensures the crystallization efficiency; alcohol closed loop circulation is realized through solvent recovery system, which reduces the raw material cost, and the energy consumption is reduced by using rectification waste heat heating.

Description

Technical Field

[0001] This utility model belongs to the field of dicumyl peroxide production technology, specifically relating to a dicumyl peroxide graded crystallization device. Background Technology

[0002] Dicumyl peroxide (DCP) is an organic peroxide that plays an important role in industrial production. It is often used as a vulcanizing agent, crosslinking agent, and initiator for polymer materials. In terms of preparation, DCP is usually produced by a series of chemical reactions such as oxidation and condensation of cumyl peroxide. The crystallization process using alcohol as a solvent is the key step in the purification of DCP, which aims to remove impurities and obtain a high-purity product.

[0003] Currently, many crystallization devices employ intermittent batch crystallization, making continuous production difficult. Furthermore, the limited cooling methods result in low crystallization efficiency. Secondly, insufficient temperature control precision during crystallization leads to a high proportion of fine and powdery crystals, a low yield of large crystals, and low purity of the powdery crystals, making it difficult to guarantee product purity. Finally, existing devices consume large amounts of solvent, resulting in significant raw material waste and a substantial increase in production costs.

[0004] CN203833848U discloses a continuous crystallization system for dicumyl peroxide, comprising a feed tank, a crystallization cooler, a crystallizer, a centrifuge, and a circulation system connected in sequence. Continuous crystallization improves the efficiency of the crystallization process, and the overflow of the mother liquor eliminates fine crystals, thereby improving the uniformity of crystal particles. However, in this method, only the overflowing fine crystals are eliminated; most fine crystals do not overflow with the mother liquor and therefore cannot be eliminated. Thus, the method has limited effectiveness in improving the uniformity of product particles. Furthermore, the crystallizer requires precise control of the overflow of the mother liquor, necessitating the coordination of multiple pumps and storage tanks, resulting in high equipment investment and maintenance costs, and significant operational difficulties.

[0005] CN217613021U discloses a secondary crystallization system for dicumyl peroxide. The system is designed with mother liquor recovery and circulation. The mother liquor from the horizontal centrifuge is processed by the evaporator, condenser, and distillation tank, and methanol is returned to the recooling crystallization tank, while the residual liquid is returned to the crystallization batching tank. The mother liquor from the vertical centrifuge is returned to the recooling crystallization tank via the recrystallization mother liquor tank. This system significantly improves product purity and yield through the process of primary crystallization, melting, and secondary crystallization. The graded recovery of mother liquor and solvent reduces raw material waste. However, the remelting operation requires high energy consumption, the production cycle is relatively long, and the equipment investment and maintenance costs increase accordingly. In addition, the use of methanol as a solvent results in high toxicity.

[0006] Therefore, it is of great significance to develop a crystallization device for the production of dicumyl peroxide that has a simple process, good crystallization effect, and low energy consumption. Utility Model Content

[0007] The purpose of this invention is to provide a graded crystallization apparatus for dicumyl peroxide to solve the problems of complex structure and poor crystallization effect in existing dicumyl peroxide crystallization apparatuses.

[0008] To solve the above-mentioned problems, the technical solution adopted by this utility model is as follows:

[0009] A dicumyl peroxide fractional crystallization apparatus includes a pretreatment tank, a distillation column, and an alcohol storage tank. The distillation column is connected to a filter via a transfer pump, and the filter is connected to the pretreatment tank. The bottom of the pretreatment tank is connected to a primary crystallization tank via a precooler. The primary crystallization tank is sequentially connected to a primary centrifuge, a secondary crystallization tank, a secondary centrifuge, and a product tank. The bottom of both the primary and secondary centrifuges is equipped with pipelines connecting to the mother liquor distillation column, and the bottom of the mother liquor distillation column is connected to a by-product tank. The alcohol storage tank is equipped with pipelines connecting to the primary and secondary crystallization tanks, and liquid regulating valves are installed on the pipelines.

[0010] Preferably, a three-way control valve is installed on the pipeline connecting the alcohol storage tank and the primary crystallizer, and a branch line is installed at the three-way control valve to connect to the feed inlet at the top of the filter.

[0011] Preferably, the bottom of the primary centrifuge is provided with a pipeline for returning to the upper part of the pretreatment tank, and the outlet of the primary centrifuge is provided with a mother liquor filter. The solid particle outlet of the mother liquor filter is provided with a pipeline for returning to the primary crystallizer. This is used to return the filtered dicumyl peroxide crystals as seed crystals to the primary crystallizer, so as to avoid the return to the pretreatment tank causing pipeline blockage or affecting the subsequent crystallization efficiency.

[0012] Preferably, the top of the mother liquor distillation column is connected to a condenser, the condenser is connected to a recycled alcohol storage tank, and the recycled alcohol storage tank is equipped with pipelines connecting to a secondary centrifuge and a secondary crystallizer; the recycled alcohol storage tank is also equipped with a branch line connecting to a pretreatment tank.

[0013] Preferably, a level gauge is installed on the pretreatment tank to ensure that the concentration of the raw material entering the precooler is uniform, providing stable initial conditions for subsequent crystallization. Furthermore, a level gauge is installed on the top of the secondary crystallization tank to ensure the concentration of the crystallizing liquid during secondary crystallization.

[0014] Preferably, the secondary crystallizer has a double-jacketed structure. The inner jacket is connected to the top of the mother liquor distillation column through a gas phase alcohol pipeline. The bottom of the inner jacket is provided with a condensed alcohol outlet, which is connected to the inlet of the condenser through an alcohol condensate pipeline. This is used to dissolve dicumyl peroxide in alcohol for secondary crystallization. Furthermore, a pressure gauge is installed on the gas phase alcohol pipeline, and the entire process requires heat preservation.

[0015] Preferably, the outer jacket of the secondary crystallizer is provided with a circulating water inlet for injecting cooling water or warm water, and the side wall of the secondary crystallizer is provided with a seed injection pipeline.

[0016] Preferably, agitators are installed in the pretreatment tank, the primary crystallization tank, and the secondary crystallization tank. The agitators in the pretreatment tank and the primary crystallization tank are anchor-type agitators, while the agitators in the secondary crystallization tank are a combination agitators consisting of an upper straight agitator and a lower anchor-type agitator.

[0017] Preferably, both the pretreatment tank and the primary crystallizer are jacketed structures, with a warm water inlet on the jacket of the pretreatment tank and a cooling water inlet on the jacket of the primary crystallizer.

[0018] Preferably, the pretreatment tank is provided with a pipeline connected to the precooler to transport the alcohol vapor generated in the pretreatment tank to the precooler for condensation, so as to prevent the high temperature of the DCP concentrate from the bottom of the distillation column from causing the solvent alcohol to vaporize when mixed.

[0019] The crystallization process of the dicumyl peroxide fractional crystallization apparatus of this invention is as follows:

[0020] After the reaction is complete, the liquid feed enters a distillation column to remove unreacted cumene. It is then collected from the bottom of the column and pumped to a filter to remove mechanical impurities before entering a pretreatment tank. The pretreatment tank is maintained at 60°C by circulating warm water through a jacket, and the material is uniformly stirred using an anchor agitator. Simultaneously, alcohol solvent is injected based on the level gauge reading to ensure the material meets the process concentration, providing uniform initial conditions for subsequent crystallization. The pretreated material is then conveyed from the bottom to a precooler for initial cooling, and subsequently enters the primary crystallizer. The primary crystallizer's jacket is circulated with cooling water, and the anchor agitator further slows the cooling process. Larger DCP crystals are precipitated. The slurry after primary crystallization enters a primary centrifuge to separate coarse DCP crystals and mother liquor. The coarse crystals are transported through pipelines to a secondary crystallizer for the next purification stage. The mother liquor separated by the centrifuge is first filtered through a mother liquor filter (50-80 mesh) to remove the fine crystals entrained in it. The fine crystals are returned to the primary crystallizer through a branch as seed crystals to avoid secondary nucleation and uneven particle size. Part of the filtered mother liquor is recycled to the pretreatment tank for use. The insufficient alcohol is supplemented through the alcohol storage tank to ensure the initial concentration. Part of it is sent to the mother liquor distillation column for purification to recover the alcohol solvent.

[0021] The crystals entering the secondary crystallizer are kept in suspension by the combined agitator (upper straight agitator and lower anchor agitator). Alcohol storage tanks and recycled alcohol storage tanks replenish the secondary crystallizer with alcohol solvent through pipelines. Simultaneously, warm water is introduced into the outer jacket through the circulating water inlet to regulate the temperature and ensure complete dissolution of dicumyl peroxide. After the dicumyl peroxide dissolves, the circulating water is switched from heat-insulating water to cooling water for cooling crystallization. At the same time, seed crystals are injected through the seed inlet. The liquid level gauge on the top of the tank monitors the liquid volume in real time to ensure a stable crystallization concentration (avoiding crystal dissolution due to excessive solvent or excessively high concentration). (Fine crystal formation), the slurry after secondary crystallization enters a secondary centrifuge. The upper part of the secondary centrifuge is connected to a recycled alcohol storage tank, which can wash the product after centrifugation. Finally, high-purity crystals are transported to the product tank as the final product. The secondary mother liquor is also transported to the mother liquor distillation tower to recover alcohol. When a stable gas phase is formed at the top of the mother liquor distillation tower, the dissolution of dicumyl peroxide is achieved by heating with an internal jacket. The gas phase alcohol enters the inner jacket of the secondary crystallizer through a pipeline. The gas phase alcohol condenses and releases heat in the jacket, maintaining a suitable dissolution temperature in the secondary crystallizer. The condensed alcohol enters the condenser through a pipeline from the bottom outlet.

[0022] The mother liquor (containing alcohol, a small amount of DCP and impurities) from the primary and secondary centrifuges enters the mother liquor distillation column, where alcohol and impurities are separated by heating. A portion of the vaporous alcohol at the top of the column is transported to the inner jacket of the secondary crystallizer (as a heat source) through a vaporous alcohol pipeline. Finally, the vaporous alcohol at the top of the column enters the condenser and is condensed into liquid alcohol, which is stored in a recycled alcohol storage tank for later use. A portion of the alcohol in the recycled alcohol storage tank is used to replenish the solvent demand of the secondary crystallizer, while the other portion is returned to the pretreatment tank through a branch line, realizing the recycling of alcohol solvent. The high-boiling-point impurities remaining at the bottom of the column are transported to the by-product tank for waste treatment. The crystallization unit is equipped with a temperature control system to monitor the temperature during the crystallization process.

[0023] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0024] This invention employs a graded crystallization process. The first-stage crystallization precipitates large, coarse crystals to remove impurities, while the second-stage crystallization dissolves and recrystallizes to further purify the product and improve its purity. Simultaneously, fine crystals obtained from the mother liquor filter are used to replace seed crystals for induced crystallization, ensuring the crystallization efficiency of the first-stage crystallization and guaranteeing continuous and stable production. The second-stage crystallization tank uses a composite paddle combined with temperature control and seed crystal induction to ensure crystallization efficiency.

[0025] This invention achieves a closed-loop alcohol recycling system through solvent recovery, reducing raw material costs, and utilizes the waste heat from distillation for heating, thereby reducing energy consumption. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the structure of the dicumyl peroxide fractional crystallization apparatus of this utility model.

[0027] In the diagram: 1. Pretreatment tank; 2. Primary crystallizer; 3. Distillation column; 4. Primary centrifuge; 5. Secondary crystallizer; 6. Secondary centrifuge; 7. Mother liquor distillation column; 8. Product tank; 9. By-product tank; 10. Precooler; 11. Alcohol storage tank; 12. Condenser; 13. Transfer pump; 14. Filter; 15. Three-way control valve; 16. Liquid regulating valve; 17. Recycled alcohol storage tank; 18. Gas phase alcohol pipeline; 19. Alcohol condensate pipeline; 20. Seed crystal injection pipeline; 21. Level gauge; 22. Mother liquor filter. Detailed Implementation

[0028] The specific technical solution of this utility model will be further described below with reference to the accompanying drawings.

[0029] like Figure 1 As shown, the dicumyl peroxide fractional crystallization apparatus of this invention includes a pretreatment tank 1, a distillation column 3, and an alcohol storage tank 11. The distillation column 3 is connected to a filter 14 via a transfer pump 13, and the filter 14 is connected to the pretreatment tank 1. The bottom of the pretreatment tank 1 is connected to a primary crystallization tank 2 via a precooler 10. The primary crystallization tank 2 is sequentially connected to a primary centrifuge 4, a secondary crystallization tank 5, a secondary centrifuge 6, and a product tank 8. The bottoms of the primary centrifuge 4 and the secondary centrifuge 6 are each provided with pipelines connected to a mother liquor distillation column 7, and the bottom of the mother liquor distillation column 7 is connected to a by-product tank 9. The alcohol storage tank 11 is provided with pipelines connected to the primary crystallization tank 2 and the secondary crystallization tank 5, and liquid regulating valves 16 are provided on the pipelines. The pretreatment tank 1 is provided with pipelines connected to the precooler 10.

[0030] A three-way control valve 15 is installed on the pipeline connecting the alcohol storage tank 11 and the primary crystallizer 2. A branch line is installed at the three-way control valve 15 and connected to the top inlet of the filter 14.

[0031] The bottom of the first-stage centrifuge 4 is equipped with a pipeline for reflux to the upper part of the pretreatment tank 1, and the outlet of the first-stage centrifuge 4 is equipped with a mother liquor filter 22. The solid particle outlet of the mother liquor filter 22 is equipped with a pipeline for reflux to the first-stage crystallization tank 2.

[0032] The top of the mother liquor distillation column 7 is connected to the condenser 12, and the condenser 12 is connected to the recycled alcohol storage tank 17. The recycled alcohol storage tank 17 is equipped with pipelines that connect to the secondary centrifuge 6 and the secondary crystallizer 5. The recycled alcohol storage tank 17 is also equipped with a branch line that connects to the pretreatment tank 1.

[0033] The secondary crystallizer 5 has a double-jacketed structure. The inner jacket is connected to the top of the mother liquor distillation column 7 through the gas phase alcohol pipeline 18. The bottom of the inner jacket is provided with a condensed alcohol outlet, which is connected to the inlet of the condenser 12 through the alcohol condensate pipeline 19. The outer jacket of the secondary crystallizer 5 is provided with a circulating water injection port, and the side wall of the secondary crystallizer 5 is provided with a seed crystal injection pipeline 20.

[0034] Both the pretreatment tank 1 and the secondary crystallization tank 5 are equipped with level gauges 21 at the top; each of the pretreatment tank 1, the primary crystallization tank 2, and the secondary crystallization tank 5 is equipped with an agitator. The agitators in the pretreatment tank 1 and the primary crystallization tank 2 are anchor-type agitators, while the agitator in the secondary crystallization tank 5 is a combination agitator consisting of an upper straight agitator and a lower anchor-type agitator; both the pretreatment tank 1 and the primary crystallization tank 2 are jacketed structures. The jacket of the pretreatment tank 1 is equipped with a warm water inlet, and the jacket of the primary crystallization tank 2 is equipped with a cooling water inlet.

[0035] The crystallization process of the dicumyl peroxide fractional crystallization apparatus of this invention is as follows:

[0036] After the reaction is complete, the liquid enters the distillation column 3 to remove unreacted cumene. It is then collected from the bottom of the column and pumped by pump 13 to filter 14. After filtering to remove mechanical impurities, it enters the pretreatment tank 1. The pretreatment tank 1 is maintained at 60°C by circulating warm water through its jacket, and the material is uniformly stirred by an anchor agitator. Simultaneously, alcohol solvent is injected according to the level gauge 21 to ensure the material meets the process concentration, providing uniform initial conditions for subsequent crystallization. The pretreated material is then conveyed from the bottom to the precooler 10 for initial cooling (30-35°C). The precooler uses circulating water as the cooling medium. It then enters the primary crystallizer 2. The primary crystallizer 2 is circulated with cooling water through its jacket, and with the help of the anchor agitator, the liquid is slowly cooled to 10- At 15℃, DCP is induced to precipitate larger crystal particles. The slurry after primary crystallization enters the primary centrifuge 4 to separate DCP coarse crystals and mother liquor. The coarse crystals are transported through pipeline to the secondary crystallizer 5 for the next purification stage. The mother liquor separated by the centrifuge is first filtered through the mother liquor filter 22 (50-80 mesh) to remove the fine crystals entrained in it. The fine crystals are returned to the primary crystallizer 2 through a branch as seed crystals to avoid secondary nucleation and uneven particle size. Part of the filtered mother liquor is refluxed (the reflux ratio is 50-60 wt.%) to the pretreatment tank 1 for use. The insufficient alcohol is supplemented through the alcohol storage tank 11 to ensure the initial concentration. Part of it enters the mother liquor distillation column 7 for purification to recover the alcohol solvent.

[0037] The crystals entering the secondary crystallization tank 5 are kept in suspension by the combined stirring paddles (upper straight paddle and lower anchor-type stirring paddle). Alcohol storage tank 11 and recycled alcohol storage tank 17 replenish alcohol solvent to the secondary crystallization tank 5 through pipelines. Simultaneously, warm water is introduced into the outer jacket through the circulating water inlet to regulate the temperature and ensure complete dissolution of dicumyl peroxide. After the dicumyl peroxide dissolves, the circulating water is switched from heat preservation water to cooling water for slow cooling and crystallization (ultimately cooling to 15-20℃). Simultaneously, seed crystals are injected through the seed injection pipeline 20. The liquid level gauge 21 on the tank top monitors the liquid volume in real time to ensure stable crystallization concentration. After secondary crystallization... The slurry enters the secondary centrifuge 6, which is connected to the recycled alcohol storage tank 17 at the top. This allows for the washing of the centrifuged product. Finally, the high-purity crystals are transported to the product tank 8 as the final product. The secondary mother liquor is also transported to the mother liquor distillation tower 7 to recover alcohol. When a stable gas phase is formed at the top of the mother liquor distillation tower 7, the dissolution of dicumyl peroxide is achieved by heating with an internal jacket. The gas phase alcohol enters the inner jacket of the secondary crystallizer 5 through the gas phase alcohol pipeline 18. The gas phase alcohol condenses and releases heat in the jacket, maintaining a suitable dissolution temperature in the secondary crystallizer 5. The condensed alcohol enters the condenser 12 through the alcohol condensate pipeline 19 at the bottom outlet.

[0038] The mother liquor (containing alcohol, a small amount of DCP and impurities) from the primary centrifuge 4 and the secondary centrifuge 6 enters the mother liquor distillation column 7. The temperature at the top of the mother liquor distillation column 7 is 78-85℃, and the temperature at the bottom is 105-110℃. The alcohol and impurities are separated by steam heating. Part of the vapor phase alcohol at the top of the column is transported to the inner jacket of the secondary crystallizer 5 (as a heat source) through the vapor phase alcohol pipeline 18. Finally, the vapor phase at the top of the column enters the condenser 12 and is condensed into liquid alcohol, which is stored in the recycled alcohol storage tank 17 for later use. Part of the alcohol in the recycled alcohol storage tank 17 is used to supplement the solvent demand of the secondary crystallizer 5, and the other part is returned to the pretreatment tank 1 through a branch, realizing the recycling of alcohol solvent. The high-boiling-point impurities remaining at the bottom of the column are transported to the by-product tank 9 and treated as waste. The crystallization device is equipped with a temperature control system to detect the temperature during the crystallization process. Furthermore, when the mother liquor and alcohol are recycled to the pretreatment tank 1 and the secondary crystallizer 5, liquid regulating valves 16 are installed on the pipeline to ensure production stability.

Claims

1. A fractional crystallization apparatus for dicumyl peroxide, characterized in that, The system includes a pretreatment tank (1), a distillation column (3), and an alcohol storage tank (11). The distillation column (3) is connected to a filter (14) via a transfer pump (13). The filter (14) is connected to the pretreatment tank (1). The bottom of the pretreatment tank (1) is connected to a primary crystallizer (2) via a precooler (10). The primary crystallizer (2) is connected in sequence to a primary centrifuge (4), a secondary crystallizer (5), a secondary centrifuge (6), and a product tank (8). The bottom of the primary centrifuge (4) and the secondary centrifuge (6) are both equipped with pipelines connected to the mother liquor distillation column (7). The bottom of the mother liquor distillation column (7) is connected to the by-product tank (9). The alcohol storage tank (11) is equipped with pipelines connected to the primary crystallizer (2) and the secondary crystallizer (5). A liquid regulating valve (16) is installed on the pipelines.

2. The dicumyl peroxide fractional crystallization apparatus according to claim 1, characterized in that, A three-way control valve (15) is installed on the pipeline connecting the alcohol storage tank (11) and the primary crystallizer (2). A branch is installed at the three-way control valve (15) and connected to the feed inlet at the top of the filter (14).

3. The dicumyl peroxide fractional crystallization apparatus according to claim 1, characterized in that, The bottom of the first-stage centrifuge (4) is equipped with a pipeline for reflux to the upper part of the pretreatment tank (1), and the outlet of the first-stage centrifuge (4) is equipped with a mother liquor filter (22). The solid particle outlet of the mother liquor filter (22) is equipped with a pipeline for reflux to the first-stage crystallizer (2).

4. The dicumyl peroxide fractional crystallization apparatus according to claim 1, characterized in that, The top of the mother liquor distillation column (7) is connected to the condenser (12), the condenser (12) is connected to the recycled alcohol storage tank (17), the recycled alcohol storage tank (17) is provided with pipelines connected to the secondary centrifuge (6) and the secondary crystallizer (5); the recycled alcohol storage tank (17) is also provided with a branch line connected to the pretreatment tank (1).

5. The dicumyl peroxide fractional crystallization apparatus according to claim 4, characterized in that, The secondary crystallizer (5) has a double-jacket structure. The inner jacket is connected to the top of the mother liquor distillation column (7) through the gas phase alcohol pipeline (18). The bottom of the inner jacket is provided with a condensed alcohol outlet, which is connected to the inlet end of the condenser (12) through the alcohol condensate pipeline (19).

6. The dicumyl peroxide fractional crystallization apparatus according to claim 5, characterized in that, The outer jacket of the secondary crystallizer (5) is equipped with a circulating water injection port.

7. The dicumyl peroxide fractional crystallization apparatus according to claim 1, characterized in that, The top of both the pretreatment tank (1) and the secondary crystallizer (5) is equipped with a level gauge (21), and the side wall of the secondary crystallizer (5) is equipped with a seed injection pipeline (20).

8. The dicumyl peroxide fractional crystallization apparatus according to claim 1, characterized in that... Agitators are installed in the pretreatment tank (1), the primary crystallizer (2) and the secondary crystallizer (5). The agitators in the pretreatment tank (1) and the primary crystallizer (2) are anchor-type agitators, and the agitators in the secondary crystallizer (5) are a combination agitators consisting of an upper straight agitator and a lower anchor-type agitator.

9. The dicumyl peroxide fractional crystallization apparatus according to claim 1, characterized in that, Both the pretreatment tank (1) and the primary crystallizer (2) are jacketed structures. The jacket of the pretreatment tank (1) is equipped with a warm water inlet; the jacket of the primary crystallizer (2) is equipped with a cooling water inlet.

10. The dicumyl peroxide fractional crystallization apparatus according to claim 1, characterized in that, The pretreatment tank (1) is equipped with a pipeline connected to the precooler (10).

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