Amide oil separation and ammonium sulfate crystallization integrated device and process thereof

Abstract

The invention relates to the technical field of chemical engineering, and discloses an amide oil separation and ammonium sulfate crystallization integrated device. Comprising a neutralization reactor, a settling separation tank, a pre-crystallization solution tank, a DTB crystallizer, a centrifugal machine, a settling separator, a dryer, a mother liquor tank, a condensate water tank, an amide oil decanter, an ammoximation tert-butyl alcohol tower reboiler, a mother liquor heater set, a condenser, a vacuumizing condensing unit, a stirrer set and a reactor circulating pump. The invention further comprises a process for preparing the large-particle ammonium sulfate crystal from the saturated amide oil solution, rearrangement liquid from a lactam rearrangement system and gas ammonia are added into a neutralization reactor through an external circulation pipeline, and the large-particle ammonium sulfate crystal is prepared by fully utilizing heat in the gas ammonia dissolution and neutralization reaction and crystallization process. By combining the compound additive, the seed crystal and the continuous crystallization technology, the generation of large-particle ammonium sulfate crystals is promoted, meanwhile, the crystallization process is optimized, an efficient amide oil separation and continuous crystallization mode is realized, the energy consumption is saved, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, and in particular to an integrated device for separating amide oil and crystallizing ammonium sulfate and a process thereof. Background Art

[0002] Caprolactam is an important organic chemical raw material, widely used in nylon 6 fiber, engineering plastics, coatings, and other fields. The traditional process for producing caprolactam is hydrolysis-oximation, but this method has many disadvantages. In recent years, ammoximation has gained application as a new method for producing cyclohexanone oxime. This process uses cyclohexanone, hydrogen peroxide, ammonia, and tert-butyl alcohol as raw materials to directly synthesize cyclohexanone oxime in the presence of a catalyst. The production of caprolactam from cyclohexanone oxime primarily utilizes the cyclohexanone oxime liquid-phase rearrangement method, in which cyclohexanone oxime undergoes a Beckmann rearrangement reaction in fuming sulfuric acid to produce crude caprolactam. The catalytic sulfuric acid in the rearrangement liquid is then neutralized with ammonia, producing ammonium sulfate as a byproduct in the crude caprolactam.

[0003] This process has the advantages of short process flow and less emission of three wastes. However, in the ammonium sulfate crystallization process, there are still problems such as small ammonium sulfate crystal particles, large caprolactam wrapping loss, and low energy utilization rate. The mass fraction of ammonium sulfate crystals above 2.0 mm does not exceed 5.00%, the caprolactam wrapping loss is about 0.10%, and the heat of neutralization reaction and the heat of dissolution of gaseous ammonia are not effectively utilized.

[0004] Therefore, there is an urgent need to develop a crystallization process and device that can increase the particle size of ammonium sulfate crystals, reduce caprolactam encapsulation loss, and optimize energy utilization, so as to improve the economy and sustainability of caprolactam and ammonium sulfate production. Summary of the Invention

[0005] In view of the problems existing in the above-mentioned traditional ammonium sulfate neutralization crystallization and amide oil separation process, the present invention is proposed.

[0006] Therefore, the object of the present invention is to provide an amide oil separation and ammonium sulfate crystallization integrated device and a process thereof.

[0007] To solve the above technical problems, the present invention provides the following technical solution: comprising a neutralization reactor, a sedimentation separation tank, a pre-crystallization solution tank, a DTB crystallizer, a centrifuge, a sedimentation separator, a dryer, a mother liquor tank, a condensed water tank, an amide oil decanter, an ammoximation tert-butyl alcohol tower reboiler, a mother liquor heater group, a condenser, a vacuum condensing unit, a stirrer group, a reactor circulation pump, a crystallizer circulation pump group, a slurry extraction pump, a centrifugal pump group and a high-pressure steam regulating valve group, wherein the mother liquor heater group comprises a mother liquor heater 1 and a mother liquor heater 2, the stirrer group comprises stirrer 1, stirrer 2 and stirrer 3, the crystallizer circulation pump group comprises crystallizer circulation pump 1 and crystallizer circulation pump 2, and the centrifugal pump group comprises centrifugal pump 1, centrifugal pump 2, centrifugal pump 3, centrifugal pump 4, centrifugal pump 5 and centrifugal pump 6;

[0008] The high-pressure steam regulating valve group includes a high-pressure steam regulating valve 1 and a high-pressure steam regulating valve 2. The device also includes a redraining liquid, ammonia gas, an additive feed port, a seed crystal feeding port, a high-temperature circulating water replenishment port, a pipeline group, a high-pressure steam outlet, a low-pressure steam outlet, a DTB crystallizer slurry discharge port, an exhaust pipe, a circulating water outlet, a centrifuged mother liquor, centrifuged ammonium sulfate crystals and a discharge pipe.

[0009] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, the bottom discharge end of the neutralization reactor is connected to the lower feed end of the sedimentation separation tank through a centrifugal pump 1, the bottom discharge end of the sedimentation separation tank is connected to the lower feed end of the pre-crystallization solution tank through a centrifugal pump 2, the bottom discharge end of the pre-crystallization solution tank is connected to the feed end of the mother liquor external circulation pipeline of the DTB crystallizer through a centrifugal pump 3, the slurry discharge port of the DTB crystallizer is connected to the top feed end of the centrifuge through a slurry extraction pump, the solid phase discharge end of the bottom of the centrifuge is connected to the feed end of the dryer, and its liquid phase discharge end is connected to the mother liquid tank, and the discharge end of the mother liquid tank is connected to the lower feed end of the pre-crystallization solution tank through a centrifugal pump 6.

[0010] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, the upper discharge port of the neutralization reactor is connected to a sedimentation separator, a partition is provided in the sedimentation separator, the light component caprolactam enters the right chamber through the partition and is recovered through pipeline one, the heavy component dilute ammonium sulfate solution is retained in the left chamber and returned to the lower feed end of the neutralization reactor, and the caprolactam in the upper layer of the sedimentation separation tank is recovered through pipeline two.

[0011] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, a caprolactam layer discharge port is provided at the upper portion of the DTB crystallizer and connected to the feed port of the amide oil decanter. A partition is provided in the amide oil decanter. The light component caprolactam enters the right chamber through the partition and is recovered through centrifugal pump five and pipeline three. The heavy component dilute ammonium sulfate solution is retained in the left chamber and returned to the DTB crystallizer mother liquor external circulation pipeline through centrifugal pump four.

[0012] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, the ammonium sulfate solution in the neutralization reactor is circulated and mixed by a reactor circulation pump, the rearranged liquid and gaseous ammonia enter the neutralization reactor through an external circulation pipeline, and the high-pressure steam generated by the neutralization reactor is respectively introduced into the reboiler of the ammoximation tert-butyl alcohol column and the first shell-side inlet of the mother liquor heater through the high-pressure steam outlet, and the high-pressure steam flow is regulated by the high-pressure steam regulating valve 1 and the high-pressure steam regulating valve 2.

[0013] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, the mother liquor external circulation discharge ports on the left and right sides of the DTB crystallizer are respectively connected to the mother liquor heater 1 and the mother liquor heater 2 pipe-side feed ports, and the two mother liquor heater pipe-side discharge ports are respectively returned to the mother liquor external circulation feed ports on the corresponding sides of the DTB crystallizer through the crystallizer circulation pump 1 and the crystallizer circulation pump 2, and a seed crystal feeding port is provided at the top of the DTB crystallizer.

[0014] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, a low-pressure steam outlet is provided at the middle of the top of the DTB crystallizer to connect to the shell-side inlet of the condenser, and the shell-side outlet of the condenser is respectively connected to the condensate tank and the vacuum condensing unit, and the vacuum condensing unit discharges non-condensable gas through the exhaust pipe.

[0015] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, the pre-crystallization solution tank is provided with an additive feed port at the top, the outer wall of the sedimentation separation tank is provided with thermal insulation cotton, the pre-crystallization solution tank is a mixing kettle with a jacket, the high-temperature circulating water at the second shell side outlet of the mother liquor heater is connected to the circulating water inlet at the bottom end of the pre-crystallization solution tank jacket, and the circulating water outlet at the top end of the pre-crystallization solution tank jacket is divided into two routes, one route is connected to the water supply port of the external circulation pipeline of the neutralization reactor and the water supply port of the sedimentation separation tank, and the other route is discharged through the circulating water outlet.

[0016] As a preferred embodiment of the integrated device for amide oil separation and ammonium sulfate crystallization of the present invention, the centrifuged ammonium sulfate crystals produced by the centrifuge separation enter the dryer for drying and are finally discharged through the discharge pipe, and the centrifuged mother liquor enters the mother liquor tank.

[0017] The invention also provides a preparation process.

[0018] A process for preparing large-particle ammonium sulfate crystals from a saturated amide oil solution is prepared using the above-mentioned integrated device for amide oil separation and ammonium sulfate crystallization, comprising the following steps:

[0019] S1. The rearrangement liquid and gaseous ammonia from the caprolactam rearrangement system are fed into the neutralization reactor through an external circulation pipeline. The solution in the reactor absorbs the heat released by the neutralization reaction and the dissolution of the gaseous ammonia, and part of the water is vaporized. The pressure in the neutralization reactor is 100-110 kPa and the temperature is 100-105° C. 38% to 40% of the high-pressure steam generated is used for the reboiler of the ammoximation tert-butyl alcohol column, and 60% to 62% is used for the mother liquor heater 1. The final high-temperature steam-water mixture is used for the mother liquor heater 2.

[0020] S2, the upper layer of the neutralization reactor is a caprolactam solution, the middle layer is a dilute ammonium sulfate solution, and the lower layer is a concentrated ammonium sulfate solution. A sedimentation separator is provided outside the neutralization reactor. The amide oil containing dilute ammonium sulfate in the upper layer enters the sedimentation separator through the upper discharge port of the neutralization reactor. The light component caprolactam flows through the partition into the right chamber of the sedimentation separator and is finally recovered through pipeline 1. The heavy component dilute ammonium sulfate solution continues to remain on the left side of the chamber and finally returns to the lower feed end of the neutralization reactor;

[0021] S3, the ammonium sulfate solution after the primary separation of amide oil is supplemented with some waste heat circulating water in the sedimentation separation tank to completely dissolve the small amount of precipitated ammonium sulfate crystals, releasing the caprolactam wrapped by the ammonium sulfate crystals, and the caprolactam in the upper layer of the sedimentation separation tank is recovered again through pipeline 2;

[0022] S4. Adding a compound additive to the ammonium sulfate solution after the secondary separation of the amide oil in the pre-crystallization solution tank, wherein the ammonium sulfate solution in the pre-crystallization solution tank is a saturated solution containing caprolactam, wherein the caprolactam accounts for 0.65% to 0.75% by mass of the ammonium sulfate solution, the additive manganese sulfate accounts for 1.20% to 1.30% by mass of the ammonium sulfate in the solution, and the additive AS-22 accounts for 0.09% to 0.18% by mass of the ammonium sulfate in the solution;

[0023] S5. The ammonium sulfate solution containing the compound additive enters the DTB crystallizer through the mother liquor external circulation pipeline for continuous vacuum evaporation and crystallization. The mother liquor heater group and the flash evaporation and cooling of the ammonium sulfate solution itself provide heat for evaporation and crystallization. The supersaturation of the solution comes from the evaporation of water in the solution and the cooling of the solution itself. Since a continuous crystallization process is adopted, seed crystals as a crystallization inducer only need to be added at the start of the operation. The seed crystal particle size is 0.1-0.5mm, and the seed crystal amount accounts for 0.05% to 0.07% of the total ammonium sulfate mass fraction in the DTB crystallizer.

[0024] S6, DTB crystallizer stirring speed is controlled at 520-530rpm, temperature is controlled at 74-76℃, solution pH is controlled at 3.8-4.1, absolute pressure is maintained at 27.0-30.0kPa, average solution residence time is 4.0h, and the total supersaturation ratio S of ammonium sulfate solution in the crystallizer is controlled at 1.15-1.20;

[0025] S7, after the ammonium sulfate solution is subjected to secondary separation of amide oil, a saturated solution of caprolactam is obtained. Caprolactam still has a low solubility in the saturated aqueous solution of ammonium sulfate, and this portion of caprolactam cannot be separated by solution stratification. As water evaporates in the DTB crystallizer, caprolactam continuously precipitates from the ammonium sulfate solution and accumulates on the liquid surface. This portion of caprolactam is recovered again through pipeline three by setting an amide oil decanter outside the DTB crystallizer;

[0026] After the ammonium sulfate crystals and mother liquor produced at the crystal slurry discharge port of S8 and DTB crystallizers are separated into solid and liquid by the centrifuge, the centrifuged ammonium sulfate crystals are sent to the dryer from the solid phase discharge port for drying, and the centrifuged mother liquor enters the mother liquor tank from the liquid phase discharge port and is returned to the pre-crystallization solution tank for recycling under the action of centrifugal pump 6.

[0027] Beneficial effects of the present invention:

[0028] 1. The present invention fully utilizes the heat of dissolution of gaseous ammonia and the heat of reaction of the neutralization reaction of sulfuric acid and ammonia through the neutralization reactor, and uses the generated high-pressure steam externally. The energy of the device is reasonably and effectively utilized. Through the three-stage separation action of the sedimentation separator, the sedimentation separation tank and the amide oil decanter, the ammonium sulfate solution and the amide oil are efficiently separated while reducing the encapsulation loss of caprolactam.

[0029] 2. The present invention promotes the growth of large-particle ammonium sulfate crystals and effectively regulates the crystal structure of the crystals by adding manganese sulfate and AS-22 as compound additives. In particular, the successful development of the additive AS-22 makes it possible to prepare large-particle ammonium sulfate crystals from a saturated amide oil solution. Because the presence of caprolactam has a negative impact on the formation of large-particle ammonium sulfate crystals and the promoting effect of the additive, the additive makes it possible to produce a high-yield large-particle ammonium sulfate crystal process without the need for recrystallization technology.

[0030] 3. The present invention separates the neutralization reaction from the ammonium sulfate crystallization, separates the amide oil in advance, and the caprolactam content in the DTB crystallizer is already very small, making it easier to control the crystallization kinetics and ensuring more stable crystal growth. The addition of seed crystals at the start-up of the process reduces the supersaturation of the solution, avoids explosive nucleation, and enables the crystallization system to operate stably. The ammonium sulfate particles precipitate uniformly and grow in an orderly manner, thereby improving the efficiency and quality of crystal growth while controlling the number of crystals generated. After the system is operating stably, the addition of seed crystals is no longer required.

[0031] 4. The present invention adopts a continuous vacuum evaporation crystallization operation mode, combined with compound additives and seed crystal technology, so that the prepared large-particle ammonium sulfate crystals have an extremely high proportion and high crystallinity; and the compound additives manganese sulfate and AS-22 are insoluble in caprolactam. AS-22 is a non-toxic and harmless substance that does not contain radioactive elements and metal elements, all of which are elements required by crops. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0033] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0034] Figure 2 It is a process flow chart of the present invention.

[0035] Figure 3 This is an example diagram of the SEM image of the crystalline product of the present invention.

[0036] Figure 4 This is a comparative SEM image of the crystalline product of the present invention.

[0037] Figure 5 FTIR spectra of the crystalline products of the embodiments and comparative examples of the present invention.

[0038] Figure 6 The XRD patterns of the crystalline products of the embodiments and comparative examples of the present invention are shown in FIG.

[0039] In the figure: 1. Neutralization reactor; 2. Separation tank; 3. Pre-crystallization solution tank; 4. DTB crystallizer; 5. Centrifuge; 6. Separation tank; 7. Dryer; 8. Mother liquor tank; 9. Condensate tank; 10. Amide oil decanter; 11. Reboiler for ammoximation tert-butyl alcohol column; 12. Mother liquor heater group; 12-1. Mother liquor heater 1; 12-2. Mother liquor heater 2; 13. Condenser; 14. Vacuum condensing unit; 15. Agitator group; 15-1. Agitator 1; 15-2. Agitator 2; 15-3. Agitator 3; 16. Reactor circulation pump; 17. Crystallizer circulation pump group; 17-1. Crystallizer circulation pump 1; 17-2. Crystallizer circulation pump 2; 18. Slurry extraction pump; 19. Centrifugal pump group; 19-1 , centrifugal pump one; 19-2, centrifugal pump two; 19-3, centrifugal pump three; 19-4, centrifugal pump four; 19-5, centrifugal pump five; 19-6, centrifugal pump six; 20, high-pressure steam regulating valve group; 20-1, high-pressure steam regulating valve one; 20-2, high-pressure steam regulating valve two; 21, heavy discharge liquid; 22, gaseous ammonia; 23, additive feed port; 24, seed crystal feeding port; 25, high-temperature circulating water replenishment port; 26, pipeline group; 26-1, pipeline one; 26-2, pipeline two; 26-3, pipeline three; 27, high-pressure steam outlet; 28, low-pressure steam outlet; 29, DTB crystallizer slurry discharge port; 30, exhaust pipe; 31, circulating water outlet; 32, centrifuged mother liquor; 33, centrifuged ammonium sulfate crystals; 34, discharge pipe. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it necessarily refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0043] Furthermore, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, when describing the embodiments of the present invention, cross-sectional views illustrating device structures may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0044] Example 1

[0045] Reference Figure 1 , which is the first embodiment of the present invention, provides an integrated device for amide oil separation and ammonium sulfate crystallization, which includes a neutralization reactor 1, a sedimentation separation tank 2, a pre-crystallization solution tank 3, a DTB crystallizer 4, a centrifuge 5, a sedimentation separator 6, a dryer 7, a mother liquor tank 8, a condensed water tank 9, an amide oil decanter 10, an ammoximation tert-butyl alcohol column reboiler 11, a mother liquor heater group 12, a condenser 13, a vacuum condensing unit 14, a stirrer group 15, a reactor circulation pump 16, a crystallizer circulation pump group 17, a slurry extraction pump 18, a centrifuge The pump group 19 and the high-pressure steam regulating valve group 20, the mother liquor heater group 12 includes the mother liquor heater 1 12-1 and the mother liquor heater 2 12-2, the agitator group 15 includes the agitator 1 15-1, the agitator 2 15-2 and the agitator 3 15-3, the crystallizer circulation pump group 17 includes the crystallizer circulation pump 1 17-1 and the crystallizer circulation pump 2 17-2, the centrifugal pump group 19 includes the centrifugal pump 1 19-1, the centrifugal pump 2 19-2, the centrifugal pump 3 19-3, the centrifugal pump 4 19-4, the centrifugal pump 5 19-5 and the centrifugal pump 6 19-6.

[0046] The high-pressure steam regulating valve group 20 includes a high-pressure steam regulating valve 1 20-1 and a high-pressure steam regulating valve 2 20-2. The device also includes a rearrangement liquid 21, ammonia gas 22, an additive feed port 23, a seed crystal feeding port 24, a high-temperature circulating water replenishment port 25, a pipeline group 26, a high-pressure steam outlet 27, a low-pressure steam outlet 28, a DTB crystallizer slurry discharge port 29, an exhaust pipe 30, a circulating water outlet 31, a centrifuged mother liquor 32, centrifuged ammonium sulfate crystals 33 and a discharge pipe 34.

[0047] Among them, through the series arrangement of the neutralization reactor 1, the sedimentation separation tank 2, the pre-crystallization solution tank 3 and the DTB crystallizer 4, and the forced circulation system formed by the reactor circulation pump 16, the continuous production of amide oil separation and ammonium sulfate crystallization is realized, wherein the high-pressure steam outlet 27 is divided into two routes, respectively connected to the ammoximation tert-butanol tower reboiler 11 and the mother liquor heater 12-1, and the steam distribution is precisely controlled by the high-pressure steam regulating valve 1 20-1 and the high-pressure steam regulating valve 2 20-2 to improve the reaction heat utilization rate; the agitator 15-1, the agitator 2 15-2 and the agitator 3 15-3 optimize the stirring intensity for the sedimentation, pre-crystallization and crystallization stages respectively, and the symmetrical circulation flow formed by the crystallizer circulation pump 1 17-1 and the crystallizer circulation pump 2 17-2 effectively improves the uniformity of crystal growth.

[0048] Specifically, the bottom discharge end of the neutralization reactor 1 is connected to the lower feed end of the sedimentation separation tank 2 through a centrifugal pump 19-1, the bottom discharge end of the sedimentation separation tank 2 is connected to the lower feed end of the pre-crystallization solution tank 3 through a centrifugal pump 2 19-2, the bottom discharge end of the pre-crystallization solution tank 3 is connected to the mother liquor external circulation pipeline feed end of the DTB crystallizer 4 through a centrifugal pump 3 19-3, the DTB crystallizer slurry discharge port 29 is connected to the top feed end of the centrifuge 5 through a slurry extraction pump 18, the solid phase discharge end at the bottom of the centrifuge 5 is connected to the feed end of the dryer 7, and its liquid phase discharge end is connected to the mother liquor tank 8, and the discharge end of the mother liquor tank 8 is connected to the lower feed end of the pre-crystallization solution tank 3 through a centrifugal pump 6 19-6.

[0049] Among them, the material transmission system realizes three-stage progressive transportation through centrifugal pump 19-1, centrifugal pump 2 19-2 and centrifugal pump 3 19-3. The slurry extraction pump 18 directionally transports the slurry from the DTB crystallizer slurry outlet 29 to the centrifuge 5. The mother liquor reflux system composed of centrifugal pump 6 19-6 returns the centrifuged mother liquor 32 in the mother liquor tank 8 to the pre-crystallization solution tank 3 to participate in crystallization again. In conjunction with the amide oil recovery network composed of pipeline 1 26-1, pipeline 2 26-2 and pipeline 3 26-3, closed-loop utilization of materials is realized, so that the total recovery rate of caprolactam reaches more than 99.60%, and the circulation rate of ammonium sulfate mother liquor is 83% to 84%.

[0050] Furthermore, the upper discharge port of the neutralization reactor 1 is connected to the sedimentation separator 6, and a partition is provided in the sedimentation separator 6. The light component caprolactam enters the right chamber through the partition and is recovered through the pipeline 1 26-1, and the heavy component dilute ammonium sulfate solution is retained in the left chamber and returned to the lower feed end of the neutralization reactor 1. The caprolactam in the upper layer of the sedimentation separation tank 2 is recovered through the pipeline 26-2.

[0051] Among them, the sedimentation separator 6 realizes the separation of light and heavy components through the built-in partition, the caprolactam is efficiently recovered through the pipeline 1 26-1, the dilute ammonium sulfate solution returns to the neutralization reactor 1 to continue the reaction, and the outer wall of the sedimentation separation tank 2 is provided with insulation cotton to reduce heat loss. The upper layer of caprolactam is recovered for the second time through the pipeline 26-2. The double separation design reduces the caprolactam encapsulation loss to below 0.10%. At the same time, the water inlet of the sedimentation separation tank 2 can dissolve a small amount of precipitated crystals and release the encapsulated caprolactam molecules.

[0052] Preferably, a caprolactam layer discharge port is provided at the top of the DTB crystallizer 4 and connected to the feed port of the amide oil decanter 10. A partition is provided in the amide oil decanter 10. The light component caprolactam enters the right chamber through the partition and is recovered through the centrifugal pump five 19-5 and the pipeline three 26-3. The heavy component dilute ammonium sulfate solution is retained in the left chamber and returned to the DTB crystallizer 4 mother liquor external circulation pipeline through the centrifugal pump four 19-4.

[0053] Among them, the caprolactam layer on the top of the DTB crystallizer 4 is separated for the third time through the amide oil decanter 10, the centrifugal pump five 19-5 recovers the light phase through the pipeline three 26-3, the centrifugal pump four 19-4 returns the heavy phase to the crystallization system, and the seed feeding port 24 adds seeds during the start-up phase. Combined with the circulating flow controlled by the agitator three 15-3, the average particle size of the crystals reaches 1.7-1.8 mm, the proportion of large-particle crystals (≥1.4 mm) is increased to 70% to 72%, and the regularity of the crystal morphology is improved by 30%.

[0054] Furthermore, the ammonium sulfate solution in the neutralization reactor 1 is circulated and mixed through the reactor circulation pump 16, the rearrangement liquid 21 and the gaseous ammonia 22 enter the neutralization reactor 1 through the external circulation pipeline, and the high-pressure steam generated in the neutralization reactor 1 is respectively introduced into the ammoximation tert-butyl alcohol tower reboiler 11 and the mother liquor heater 12-1 shell side inlet through the high-pressure steam outlet 27, and the high-pressure steam flow is regulated by the high-pressure steam regulating valve 1 20-1 and the high-pressure steam regulating valve 2 20-2.

[0055] Among them, the heat integration system realizes the cascade utilization of thermal energy through the high-pressure steam outlet 27, the mother liquor heater 1 12-1 and the mother liquor heater 2 12-2. The high-temperature circulating water from the shell-side outlet of the mother liquor heater 2 12-2 is supplied to the jacket of the pre-crystallization solution tank 3, the water replenishment of the neutralization reactor 1 and the water replenishment of the sedimentation separation tank 2 in sequence, thereby reducing the high-pressure steam consumption of the system by 38% to 40%. The vacuum condensing unit 14 accurately controls the vacuum degree (71.0-75.0 kPa) of the DTB crystallizer 4 and discharges the non-condensable gas through the exhaust pipe 30.

[0056] Furthermore, the mother liquor external circulation discharge ports on the left and right sides of the DTB crystallizer 4 are respectively connected to the mother liquor heater 1 12-1 and the mother liquor heater 2 12-2 pipe-side feed ports, and the two mother liquor heater pipe-side discharge ports are respectively returned to the mother liquor external circulation feed ports on the corresponding sides of the DTB crystallizer 4 through the crystallizer circulation pump 1 17-1 and the crystallizer circulation pump 2 17-2. A seed crystal feeding port 24 is provided at the top of the DTB crystallizer 4.

[0057] Among them, the dryer 7 receives the centrifuged ammonium sulfate crystals 33 from the centrifuge 5, and after hot air drying, outputs the finished product with a moisture content of less than 0.10% through the discharge pipe 34. The centrifuged mother liquor 32 collected in the mother liquor tank 8 is completely recycled through the centrifugal pump 6 19-6, and the compound additive (manganese sulfate + AS-22) is added to the additive feed port 23 of the pre-crystallization solution tank 3, so that the crystal packing density is increased by 15%, the product repose angle is reduced to below 28°, and the product fluidity is significantly improved.

[0058] Furthermore, the low-pressure steam outlet 28 in the middle of the top of the DTB crystallizer 4 is connected to the shell-side inlet of the condenser 13, and the shell-side outlet of the condenser 13 is respectively connected to the condensate tank 9 and the vacuum condensing unit 14, and the vacuum condensing unit 14 discharges non-condensable gas through the exhaust pipe 30.

[0059] Among them, the low-pressure steam outlet 28 set at the top of the DTB crystallizer 4 is connected to the shell side of the condenser 13. After condensation, the low-pressure steam enters the condensed water tank 9. This part of the condensed water has no recycling value. In addition, the non-condensable gas (such as CO2, NH3, etc.) is discharged by the vacuum condensing unit 14 to ensure the stability of the vacuum degree inside the crystallizer. The DTB crystallizer 4 is equipped with a double mother liquor heater 12-1 and 12-2. The high-temperature steam-water mixture after the heat release of the ammoximation tert-butyl alcohol column reboiler 11 and the mother liquor heater 1 12-1 shell side is merged, and a portion of the high-temperature steam-water mixture generated by the shell side of other heat exchanger groups is supplemented at the high-temperature circulating water replenishment port 25. The mixture is continued to be introduced into the mother liquor heater 2 12-2 to provide heat for the DTB crystallizer 4 to maintain the vacuum evaporation crystallization operation of the crystallizer and ensure the continuous stability of the crystallization process. Through the optimized design of this steam utilization system, steam consumption is further reduced and the energy utilization efficiency of the entire system is improved.

[0060] Furthermore, an additive feed port 23 is provided at the top of the pre-crystallization solution tank 3, and insulation cotton is provided on the outer wall of the sedimentation separation tank 2. The pre-crystallization solution tank 3 is a mixing kettle with a jacket. The high-temperature circulating water at the shell outlet of the mother liquor heater 2 12-2 is connected to the circulating water inlet at the bottom end of the jacket of the pre-crystallization solution tank 3. The circulating water outlet at the top end of the jacket of the pre-crystallization solution tank 3 is divided into two routes, one of which is connected to the water supply port of the external circulation pipeline of the neutralization reactor 1 and the water supply port of the sedimentation separation tank 2, and the other is discharged through the circulating water outlet 31. The centrifuged ammonium sulfate crystals 33 separated by the centrifuge 5 enter the dryer 7 for drying, and are finally discharged through the discharge pipe 34. The centrifuged mother liquor 32 enters the mother liquor tank 8.

[0061] Among them, the additive feed port 23 of the pre-crystallization solution tank 3 can be added with crystal form regulators such as manganese sulfate or AS-22 to optimize the crystal growth morphology, change the crystal growth dynamics, and make the ammonium sulfate crystal particle size more uniform (1.7-1.8mm). The insulation cotton on the outer wall of the sedimentation separation tank 2 reduces heat loss and maintains a stable temperature in the tank (80-100°C) to avoid precipitation of ammonium sulfate solution in the tank due to temperature reduction. The high-temperature circulating water (85-90°C) of the mother liquor heater 2 12-2 first enters the pre-crystallization solution tank 3 jacket for heating, and then is diverted to the neutralization reactor 1 and the sedimentation separation tank 2 for water replenishment to achieve thermal The system can be utilized in a cascade manner, and the thermal efficiency of the system is improved by more than 40%; the centrifuged ammonium sulfate crystals 33 separated by the centrifuge 5 enter the dryer 7 for drying, and are finally discharged through the discharge pipe 34 to obtain a finished product with a low moisture content (<0.10%); after the centrifuged mother liquor 32 enters the mother liquor tank 8, it is all returned to the pre-crystallization solution tank 3 through the centrifugal pump 6 19-6 for recrystallization, forming a closed loop, realizing the full recovery of ammonium sulfate in the mother liquor, and high-yield large-particle ammonium sulfate crystals, while the crystal purity is increased to more than 99.70%, and the product fluidity (angle of repose <28°) is significantly improved, meeting the industrial-grade ammonium sulfate standard.

[0062] Example 2

[0063] Reference Figure 2 , which is the second embodiment of the present invention, is different from the previous embodiment in that this embodiment provides a process for preparing large-particle ammonium sulfate crystals from a saturated amide oil solution, including an integrated device for amide oil separation and ammonium sulfate crystallization, and the method includes the following steps:

[0064] S1, the rearrangement liquid 21 and the ammonia gas 22 from the caprolactam rearrangement system are added to the neutralization reactor 1 through the external circulation pipeline. The solution in the reactor absorbs the heat released by the neutralization reaction and the dissolution of the ammonia gas, and part of the water is vaporized. The pressure in the neutralization reactor 1 is 100-110 kPa and the temperature is 100-105° C. 38% to 40% of the high-pressure steam generated is used for the ammoximation tert-butyl alcohol column reboiler 11, and 60% to 62% is used for the mother liquor heater 12-1. The final high-temperature steam-water mixture is used for the mother liquor heater 2 12-2;

[0065] S2, the upper layer of the neutralization reactor 1 is a caprolactam solution, the middle layer is a dilute ammonium sulfate solution, and the lower layer is a concentrated ammonium sulfate solution. A sedimentation separator 6 is provided outside the neutralization reactor 1. The amide oil containing dilute ammonium sulfate in the upper layer enters the sedimentation separator 6 through the upper discharge port of the neutralization reactor 1. The light component caprolactam flows through the partition into the right chamber of the sedimentation separator 6 and is finally recovered through a pipeline 26-1. The heavy component dilute ammonium sulfate solution continues to remain on the left side of the chamber and eventually returns to the lower feed end of the neutralization reactor 1.

[0066] S3, the ammonium sulfate solution after the primary separation of amide oil is supplemented with some waste heat circulating water in the sedimentation separation tank 2 to completely dissolve the precipitated small amount of ammonium sulfate crystals, releasing the caprolactam wrapped by the ammonium sulfate crystals, and the caprolactam in the upper layer of the sedimentation separation tank 2 is recovered again through the pipeline 26-2;

[0067] S4, the ammonium sulfate solution after the secondary separation of amide oil is added with a compound additive in the pre-crystallization solution tank 3, the ammonium sulfate solution in the pre-crystallization solution tank 3 is a saturated solution containing caprolactam, the caprolactam accounts for 0.65% to 0.75% by mass of the ammonium sulfate solution, the additive manganese sulfate accounts for 1.20% to 1.30% by mass of the ammonium sulfate in the solution, and the additive AS-22 accounts for 0.09% to 0.18% by mass of the ammonium sulfate in the solution;

[0068] S5, the ammonium sulfate solution containing the compound additive enters the DTB crystallizer 4 through the mother liquor external circulation pipeline for continuous vacuum evaporation crystallization. The mother liquor heater group 12 and the flash evaporation cooling of the ammonium sulfate solution itself provide heat for evaporation crystallization. The supersaturation of the solution comes from the evaporation of water in the solution and the cooling of the solution itself. Since a continuous crystallization process is adopted, seed crystals as a crystallization inducer only need to be added at the start of the operation. The seed crystal particle size is 0.1-0.5 mm, and the amount of seed crystals accounts for 0.05% to 0.07% of the total mass fraction of ammonium sulfate in the DTB crystallizer 4;

[0069] The stirring speed of S6 and DTB crystallizer 4 is controlled at 520-530 rpm, the temperature is controlled at 74-76°C, the solution pH is controlled at 3.8-4.1, the absolute pressure is maintained at 27.0-30.0 kPa, the average residence time of the solution is 4.0 h, and the total supersaturation ratio S of the ammonium sulfate solution in the crystallizer is controlled at 1.15-1.20. Formulas (1)-(3) are supersaturation models based on evaporation rate, and formulas (4)-(6) are supersaturation models based on cooling rate. The residence time is used instead of the instantaneous time t, and the instantaneous supersaturation ratio is expressed by the total supersaturation ratio S.

[0070]

[0071] ΔC=C(t)-C eq (2)

[0072] S=C(t) / C eq (3)

[0073]

[0074] In formulas (1)-(6): V0 is the initial mass of the solvent, C0 is the initial concentration of the solute, is the solvent evaporation rate, C(t) is the real-time concentration, C eq is the saturated solubility, is the cooling rate, is the real-time concentration change rate over time, is the rate of change of saturated solubility with time, ΔC is the supersaturation (g ammonium sulfate / 100 g water), and S is the supersaturation ratio (dimensionless);

[0075] S7, after the ammonium sulfate solution undergoes secondary separation of the amide oil, a saturated solution of caprolactam is obtained. Caprolactam still has a low solubility in the saturated aqueous solution of ammonium sulfate, and this portion of caprolactam cannot be separated by solution stratification. As water evaporates in the DTB crystallizer 4, caprolactam continuously precipitates from the ammonium sulfate solution and accumulates on the liquid surface. This portion of caprolactam is recovered again through pipeline three 26-3 by providing an amide oil decanter 10 outside the DTB crystallizer 4;

[0076] After the ammonium sulfate crystals and mother liquor produced at the crystal slurry discharge port 29 of S8 and DTB crystallizer are separated into solid and liquid by the centrifuge 5, the centrifuged ammonium sulfate crystals 33 are sent to the dryer 7 from the solid phase discharge port for drying, and the centrifuged mother liquor 32 enters the mother liquor tank 8 from the liquid phase discharge port and is returned to the pre-crystallization solution tank 3 for recycling under the action of the centrifugal pump 6 19-6.

[0077] Example 3

[0078] Reference Figures 3 to 6 , which is the third embodiment of the present invention. This embodiment is different from the first embodiment in that it provides an experiment for preparing large-particle ammonium sulfate crystals from a saturated amide oil solution and a neutralization crystallization process in an enterprise's caprolactam production workshop.

[0079] According to the production scale of Comparative Example 1, the rearrangement reaction liquid enters the neutralization reactor 1 at a flow rate of 7.61 kg / s and the ammonia gas enters the neutralization reactor 1 at a flow rate of 1.42 kg / s. The temperature in the neutralization reactor 1 is 103° C. and the pressure is 110.0 kPa. The high-pressure steam generated at the top of the reactor is used externally. The crystallization temperature in the DTB crystallizer 4 is 75° C., the absolute pressure is 28.6 kPa, the solution pH is 4.0, the caprolactam accounts for 0.70% by mass of the ammonium sulfate aqueous solution, the additive manganese sulfate accounts for 1.25% by mass of the ammonium sulfate in the crystallizer, the additive AS-22 accounts for 0.14% by mass of the ammonium sulfate in the crystallizer, the total supersaturation ratio S of the ammonium sulfate solution in the crystallizer is 1.20, the amount of seed crystals added at the start-up accounts for 0.05% by mass of the ammonium sulfate in the crystallizer, and the average residence time of the solution is 4.0 h.

[0080] According to the neutralization crystallization process of Luxi Chemical, the rearrangement reaction liquid flows at a flow rate of 7.61 kg / s and the ammonia flows at a flow rate of 1.42 kg / s through the annular distributor in the DTB neutralization crystallizer and enters the guide tube. The ammonia and sulfuric acid are neutralized in the guide tube to generate ammonium sulfate solution. The crystallization temperature in the DTB neutralization crystallizer is 60 ° C, the absolute pressure is 16.5 kPa, and the solution pH is 4.2, the total supersaturation ratio S of the ammonium sulfate solution in the neutralization crystallizer is 1.35, the average residence time of the solution is 3.4 hours, and the mass fraction of caprolactam in the ammonium sulfate aqueous solution is 10.99%; the stirring paddle lifts the ammonium sulfate solution to the upper part of the guide tube. As the solution rises, water gradually evaporates. The low-temperature steam generated during the crystallization process is condensed through the condenser and returned to the circulation pipeline at the bottom of the DTB neutralization crystallizer to balance the effect of the reaction heat on water evaporation and dissolve fine crystals. The amide oil in the upper part of the clarification zone of the DTB neutralization crystallizer is separated from the ammonium sulfate solution and sent to the amide oil decanter for sedimentation separation. The ammonium sulfate solution separated in the decanter is returned to the DTB neutralization crystallizer for recycling.

[0081] Test results and data:

[0082] Related indicators Example Comparative Example Mass fraction of large crystals (≥2.0 mm) 47.05％ 4.60％ Mass fraction of large / medium-sized crystals (≥1.4 mm) 70.50％ 7.60％ Mass fraction of medium-sized crystals (1.0-2.0 mm) 31.18％ 7.50％ Mass fraction of small crystal particles (≤1.0 mm) 21.78％ 87.90％ Crystallization rate 16.64％ 25.91％ Ammonium sulfate crystal yield 19.75t / h 19.75t / h

[0083] Related indicators Example Comparative Example Average residence time of solution 4.0h 3.4h Steam temperature 103℃ 60℃ Steam production rate 10.45t / h 20.00t / h Caprolactam encapsulation loss 0.02％ 0.10％ Manganese content in ammonium sulfate crystals ≤0.45％ / AS-22 content in ammonium sulfate crystals ≤0.13％ /

[0084] It should be noted that the crystal morphology of the embodiments and comparative examples is characterized as follows Figure 3 and Figure 4 As shown, Figure 3 and Figure 4 is an SEM image of the corresponding crystalline product. It can be clearly seen from the figure that the crystalline product of the embodiment has a larger crystal particle size than that of the crystalline product of the comparative example; Figure 5 The FTIR spectra of the crystallized products of the embodiment and the comparative example are shown in Figure 1. According to the NIST chemical network database, the crystals of the embodiment and the comparative example are all pure substances of ammonium sulfate. If ammonium bisulfate crystals are generated during the crystallization process, they will be at about 1200 cm -1 A significant absorption peak appears near the surface of the ion channel. In contrast, pure ammonium sulfate only has an absorption peak at 1100 cm -1 Sulfate ions (SO4 2- ) peak, and about 1200cm -1 The peak at corresponds to the hydrogen sulfate ion (HSO4 - ) SO stretching vibration, this peak is not shown in the spectra of the examples and comparative examples, and is consistent with the standard spectrum of ammonium sulfate; Figure 6The XRD patterns of the crystalline products of the embodiment and the comparative example are highly consistent with the XRD patterns of ammonium sulfate crystals reported by Gao Yongzi, BangfuHuang et al. in the literature. The main peak intensity of the XRD pattern of the crystalline crystals of the embodiment is higher than that of the comparative example. In addition, the XRD half-width at half maximum (FWHM) of the crystalline crystals of the embodiment is 0.180°, while the FWHM of the comparative example is 0.200°. The main peak intensity of the crystalline crystals of the embodiment is higher than that of the comparative example, and its FWHM is narrower than that of the comparative example, indicating that the crystallinity of the crystalline crystals of the embodiment is higher.

[0085] In summary, this experiment verified the effectiveness of the new process in the production of large-particle ammonium sulfate crystals. Through neutralization, vacuum evaporation crystallization, solid-liquid separation, and drying, this process successfully achieved efficient production of large-particle ammonium sulfate crystals, particularly with a significant increase in the proportion of crystals larger than 2.0 mm. Furthermore, thanks to the development of additives and the optimization of the crystallization process, the ammonium sulfate crystals achieved higher crystallinity and mechanical strength, and the yield of large-particle crystals increased significantly compared to traditional processes. Energy consumption was also reduced, further optimizing the overall process's economic and environmental friendliness.

[0086] It is important to note that the construction and arrangement of the present application shown in a number of different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, directional changes, etc.) without departing substantially from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structures. Without departing from the scope of the present invention, other replacements, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments. Therefore, the invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0087] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0088] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An integrated device for amide oil separation and ammonium sulfate crystallization, characterized in that: The invention comprises a neutralization reactor (1), a sedimentation separation tank (2), a pre-crystallization solution tank (3), a DTB crystallizer (4), a centrifuge (5), a sedimentation separator (6), a dryer (7), a mother liquor tank (8), a condensed water tank (9), an amide oil decanter (10), an ammoximation tert-butyl alcohol tower reboiler (11), a mother liquor heater group (12), a condenser (13), a vacuum condensing unit (14), an agitator group (15), a reactor circulation pump (16), a crystallizer circulation pump group (17), a slurry extraction pump (18), a centrifugal pump group (19) and a high-pressure steam regulating valve group (20), wherein the mother liquor is The liquid heater group (12) includes a mother liquid heater 1 (12-1) and a mother liquid heater 2 (12-2), the stirrer group (15) includes stirrer 1 (15-1), stirrer 2 (15-2) and stirrer 3 (15-3), the crystallizer circulation pump group (17) includes crystallizer circulation pump 1 (17-1) and crystallizer circulation pump 2 (17-2), and the centrifugal pump group (19) includes centrifugal pump 1 (19-1), centrifugal pump 2 (19-2), centrifugal pump 3 (19-3), centrifugal pump 4 (19-4), centrifugal pump 5 (19-5) and centrifugal pump 6 (19-6); The high-pressure steam regulating valve group (20) comprises a high-pressure steam regulating valve 1 (20-1) and a high-pressure steam regulating valve 2 (20-2). The device also comprises a rearrangement liquid (21), ammonia gas (22), an additive feed port (23), a seed crystal feeding port (24), a high-temperature circulating water replenishment port (25), a pipeline group (26), a high-pressure steam outlet (27), a low-pressure steam outlet (28), a DTB crystallizer slurry discharge port (29), an exhaust pipe (30), a circulating water outlet (31), a centrifuged mother liquor (32), centrifuged ammonium sulfate crystals (33) and a discharge pipe (34).

2. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 1, wherein: The bottom discharge end of the neutralization reactor (1) is connected to the lower feed end of the sedimentation separation tank (2) through a centrifugal pump (19-1), the bottom discharge end of the sedimentation separation tank (2) is connected to the lower feed end of the pre-crystallization solution tank (3) through a centrifugal pump (19-2), the bottom discharge end of the pre-crystallization solution tank (3) is connected to the feed end of the mother liquor external circulation pipeline of the DTB crystallizer (4) through a centrifugal pump (19-3), the slurry discharge port (29) of the DTB crystallizer is connected to the top feed end of the centrifuge (5) through a slurry extraction pump (18), the bottom solid phase discharge end of the centrifuge (5) is connected to the feed end of the dryer (7), and its liquid phase discharge end is connected to the mother liquid tank (8), and the discharge end of the mother liquid tank (8) is connected to the lower feed end of the pre-crystallization solution tank (3) through a centrifugal pump (19-6).

3. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 2, wherein: The upper discharge port of the neutralization reactor (1) is connected to a sedimentation separator (6), and a partition is provided inside the sedimentation separator (6). The light component caprolactam enters the right chamber through the partition and is recovered through the first pipeline (26-1), and the heavy component dilute ammonium sulfate solution is retained in the left chamber and returned to the lower feed end of the neutralization reactor (1). The caprolactam in the upper layer of the sedimentation separation tank (2) is recovered through the second pipeline (26-2).

4. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 3, characterized in that: The caprolactam layer discharge port is provided on the upper part of the DTB crystallizer (4) and is connected to the feed port of the amide oil decanter (10). A partition is provided in the amide oil decanter (10). The light component caprolactam enters the right chamber through the partition and is recovered through the centrifugal pump five (19-5) and the pipeline three (26-3). The heavy component dilute ammonium sulfate solution is retained in the left chamber and returned to the mother liquor external circulation pipeline of the DTB crystallizer (4) through the centrifugal pump four (19-4).

5. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 4, characterized in that: The ammonium sulfate solution in the neutralization reactor (1) is circulated and mixed through a reactor circulation pump (16), and the rearranged liquid (21) and the gaseous ammonia (22) enter the neutralization reactor (1) through an external circulation pipeline. The high-pressure steam generated in the neutralization reactor (1) is respectively introduced into the ammoximation tert-butyl alcohol column reboiler (11) and the shell-side inlet of the mother liquor heater (12-1) through a high-pressure steam outlet (27). The flow rate of the high-pressure steam is regulated by a high-pressure steam regulating valve (20-1) and a high-pressure steam regulating valve (20-2).

6. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 5, characterized in that: The mother liquor external circulation discharge ports on the left and right sides of the DTB crystallizer (4) are respectively connected to the mother liquor heater 1 (12-1) and the mother liquor heater 2 (12-2) pipe-side feed ports, and the two mother liquor heater pipe-side discharge ports are respectively returned to the mother liquor external circulation feed ports on the corresponding sides of the DTB crystallizer (4) through the crystallizer circulation pump 1 (17-1) and the crystallizer circulation pump 2 (17-2). A seed crystal feeding port (24) is provided at the top of the DTB crystallizer (4).

7. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 6, characterized in that: A low-pressure steam outlet (28) is provided at the middle of the top of the DTB crystallizer (4) and is connected to the shell-side inlet of the condenser (13). The shell-side outlet of the condenser (13) is respectively connected to a condensate tank (9) and a vacuum condensing unit (14). The vacuum condensing unit (14) discharges non-condensable gas through an exhaust pipe (30).

8. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 7, characterized in that: An additive feed port (23) is provided on the upper portion of the pre-crystallization solution tank (3), and heat insulation cotton is provided on the outer wall of the sedimentation separation tank (2). The pre-crystallization solution tank (3) is a mixing kettle with a jacket. The high-temperature circulating water at the shell outlet of the second mother liquor heater (12-2) is connected to the circulating water inlet at the bottom end of the jacket of the pre-crystallization solution tank (3). The circulating water outlet at the top end of the jacket of the pre-crystallization solution tank (3) is divided into two routes, one of which is connected to the water supply port of the external circulation pipeline of the neutralization reactor (1) and the water supply port of the sedimentation separation tank (2), and the other is discharged through the circulating water outlet (31).

9. The integrated device for amide oil separation and ammonium sulfate crystallization according to claim 8, characterized in that: The centrifuged ammonium sulfate crystals (33) separated and produced by the centrifuge (5) enter the dryer (7) for drying and are finally discharged through the discharge pipe (34), and the centrifuged mother liquor (32) enters the mother liquor tank (8).

10. A process for preparing large-particle ammonium sulfate crystals from a saturated amide oil solution, characterized in that: The method is prepared by using an integrated device for separation of amide oil and crystallization of ammonium sulfate according to any one of claims 1 to 9, comprising the following steps: S1, the rearrangement liquid (21) and the ammonia gas (22) from the caprolactam rearrangement system are added to the neutralization reactor (1) through the external circulation pipeline. The solution in the reactor absorbs the heat released by the neutralization reaction and the dissolution of the ammonia gas, and part of the water is vaporized. The pressure in the neutralization reactor (1) is 100-110 kPa, and the temperature is 100-105° C. 38% to 40% of the generated high-pressure steam is used by the ammoximation tert-butyl alcohol column reboiler (11), and 60% to 62% is used by the mother liquor heater 1 (12-1). The final high-temperature steam-water mixture is used by the mother liquor heater 2 (12-2); S2, the upper layer of the neutralization reactor (1) is a caprolactam solution, the middle layer is a dilute ammonium sulfate solution, and the lower layer is a concentrated ammonium sulfate solution. A sedimentation separator (6) is provided outside the neutralization reactor (1). The amide oil containing dilute ammonium sulfate in the upper layer enters the sedimentation separator (6) through the upper discharge port of the neutralization reactor (1). The light component caprolactam flows through the partition into the right chamber of the sedimentation separator (6) and is finally recovered through the pipeline 1 (26-1). The heavy component dilute ammonium sulfate solution continues to remain on the left side of the chamber and finally returns to the lower feed end of the neutralization reactor (1); S3. The ammonium sulfate solution after the primary separation of the amide oil is supplemented with a portion of waste heat circulating water in the sedimentation separation tank (2) to completely dissolve the small amount of ammonium sulfate crystals precipitated, releasing the caprolactam wrapped by the ammonium sulfate crystals. The caprolactam in the upper layer of the sedimentation separation tank (2) is recovered again through the second pipeline (26-2); S4. After the secondary separation of the amide oil, the ammonium sulfate solution is added with a compound additive in a pre-crystallization solution tank (3). The ammonium sulfate solution in the pre-crystallization solution tank (3) is a saturated solution containing caprolactam, wherein the caprolactam accounts for 0.65% to 0.75% by mass of the ammonium sulfate solution, the additive manganese sulfate accounts for 1.20% to 1.30% by mass of the ammonium sulfate in the solution, and the additive AS-22 accounts for 0.09% to 0.18% by mass of the ammonium sulfate in the solution; S5. The ammonium sulfate solution containing the compound additive enters the DTB crystallizer (4) through the mother liquor external circulation pipeline for continuous vacuum evaporation crystallization. The mother liquor heater group (12) and the flash evaporation cooling of the ammonium sulfate solution itself provide heat for evaporation crystallization. The supersaturation of the solution is generated by the evaporation of water in the solution and the cooling of the solution itself. Since a continuous crystallization process is adopted, seed crystals as a crystallization inducer only need to be added at the start of the operation. The seed crystal particle size is 0.1-0.5 mm, and the amount of seed crystals used accounts for 0.05% to 0.07% of the total mass fraction of ammonium sulfate in the DTB crystallizer (4); S6, DTB crystallizer (4) agitator speed is controlled at 520-530 rpm, temperature is controlled at 74-76 ° C, solution pH is controlled at 3.8-4.1, absolute pressure is maintained at 27.0-30.0 kPa, average solution residence time is 4.0 h, and total supersaturation ratio S of ammonium sulfate solution in the crystallizer is controlled at 1.15-1.20; S7, after the ammonium sulfate solution is subjected to secondary separation of amide oil, a saturated solution of caprolactam is obtained. Caprolactam still has a low solubility in the saturated aqueous solution of ammonium sulfate, and this portion of caprolactam cannot be separated by solution stratification. As the water evaporates in the DTB crystallizer (4), caprolactam continuously precipitates from the ammonium sulfate solution and is enriched on the liquid surface. This portion of caprolactam is recovered again through pipeline three (26-3) by setting an amide oil decanter (10) outside the DTB crystallizer (4); After the ammonium sulfate crystals and mother liquor produced at the crystal slurry discharge port (29) of the S8 and DTB crystallizers are separated into solid and liquid by a centrifuge (5), the centrifuged ammonium sulfate crystals (33) are sent from the solid phase discharge port to the dryer (7) for drying, and the centrifuged mother liquor (32) is sent from the liquid phase discharge port to the mother liquor tank (8) and is returned to the pre-crystallization solution tank (3) for recycling under the action of centrifugal pump six (19-6).

Images