WO2021179638A1 - Purification method for electronic-grade ethylene carbonate, and purification apparatus - Google Patents

Purification method for electronic-grade ethylene carbonate, and purification apparatus Download PDF

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WO2021179638A1
WO2021179638A1 PCT/CN2020/125246 CN2020125246W WO2021179638A1 WO 2021179638 A1 WO2021179638 A1 WO 2021179638A1 CN 2020125246 W CN2020125246 W CN 2020125246W WO 2021179638 A1 WO2021179638 A1 WO 2021179638A1
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tank
temperature
product
ethylene carbonate
sweating
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PCT/CN2020/125246
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Chinese (zh)
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WO2021179638A9 (en
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燕增伟
吴雷雷
张生安
杜桂强
宋云瑞
郝小军
张庆博
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山东海科新源材料科技股份有限公司
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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07DHETEROCYCLIC COMPOUNDS
    • C07D317/00Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms
    • C07D317/08Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3
    • C07D317/10Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings
    • C07D317/32Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D317/34Oxygen atoms
    • C07D317/36Alkylene carbonates; Substituted alkylene carbonates
    • C07D317/38Ethylene carbonate

Definitions

  • This application relates to the technical field of preparation of electronic grade reagents, in particular to a purification method of electronic grade ethylene carbonate and a purification device thereof.
  • Ethylene carbonate also known as 1,3-dioxolane-2 ketone, ethylene carbonate, and ethylene glycol carbonate, has a molecular formula of C 3 H 4 O 3 and abbreviated as EC.
  • Ethylene carbonate is an organic solvent and organic synthesis intermediate with excellent performance, which can be used in various fields such as spinning, medicine, and plastic processing.
  • the mixed solution of ethylene carbonate and propylene carbonate has a high dielectric constant and can be used as an electrolyte for lithium ion batteries.
  • high-purity ethylene carbonate has become an important organic solvent in the electronics industry, especially in the production of lithium battery electrolyte. Since the electrolyte is the key material of lithium batteries, the performance of the electrolyte depends on the quality of various solvents in the formulation. The purity of high-purity ethylene carbonate, total alcohol content, water content, metal ion content and other single impurity components will be Directly affect the performance of the electrolyte product, and then affect the battery indicators. Therefore, the quality requirements for high-purity ethylene carbonate are getting higher and higher.
  • Chinese patent application CN107629030A provides a method for preparing electronic grade ethylene carbonate by falling film crystallization.
  • the ethylene carbonate raw material is added from the top of the crystallizer and circulates between the crystallizer and the ethylene carbonate raw material storage tank at a certain flow rate.
  • the crystallization is carried out in a gradual cooling mode, and the uncrystallized ethylene carbonate residual liquid is discharged and transported to the recovery device.
  • the crystal layer is melted by a step-by-step heating and sweating method, and the sweating liquid is cut in a certain proportion, and the sweating liquid and the residual liquid are recovered and sent back to the crystallizer.
  • the molten material liquid is returned to the raw material storage tank, and the second falling film crystallization is repeated to obtain electronic grade ethylene carbonate.
  • This method can prepare ethylene carbonate with a purity higher than 99.99%, but requires secondary falling film crystallization, high energy consumption, high perspiration cutting ratio, and low yield after primary crystallization.
  • Chinese patent application CN107501230A provides a device and method for preparing electronic grade ethylene carbonate by coupling crystallization and distillation.
  • the medium is cooled and crystallized to a certain thickness of the crystal layer, feeding is stopped, and the temperature is raised to sweat.
  • the sweated liquid after crystallization is collected and transported to the rectification tower.
  • the top product enters the second product tank, and the bottom product is recycled back to the crystallization raw material tank. After sweating is over
  • the crystals are melted and transported to the first product tank as a liquid.
  • This application realizes the recycling of the raw material liquid, and finally obtains the electronic grade ethylene carbonate product with a content of more than 99.99%.
  • the method enters the crystallizer to separate and purify impurities with a low removal rate.
  • this application provides a purification method and a purification device for electronic grade ethylene carbonate.
  • the specific solutions are as follows:
  • a purification method of electronic grade ethylene carbonate includes the following steps:
  • step S4 The crystallization of step S3 is gradually raised to heat and sweat, and the obtained sweat is subjected to the next round of crystallization;
  • step S6 The uncrystallized mother liquor in step S3 is subjected to two rectifications to obtain a second product with a purity greater than 99.990%.
  • the cooling rate of cooling crystallization in step S3 is 0.25-1.0° C./h
  • the end temperature is 32-34° C.
  • the crystallization time is 5-20 h.
  • the heating rate of heating and sweating in step S4 is 3 to 5°C/h, and the end temperature is 34 to 36.5°C.
  • the crystal melting temperature in step S5 is 40-50°C.
  • the material feed rate during seeding in step S1 is 1.0 t/h to 5.0 t/h.
  • the vacuum degree during the two rectifications in the step S6 is -99.9 to -99.0 KPa, and the temperature is 140 to 150° C., respectively.
  • This application also provides the purification device used in the above-mentioned purification method, including a falling film crystallizer, a sweating liquid tank, a mother liquor tank, a first product tank, a second product tank, a third rectification tower, and a second rectification tower;
  • the falling film crystallizer is respectively connected to the inlets of the sweating liquid tank, the mother liquid tank and the first product tank through the first discharge pipeline;
  • the sweat tank is connected to the feed port of the falling film crystallizer through a circulating pipeline;
  • the mother liquor tank is connected to the third rectification tower through a second discharge line;
  • the mother liquor tank, the third rectification tower, the second rectification tower and the second product tank are connected in sequence;
  • the raw material ethylene carbonate is first seeded and crystallized in a falling film crystallizer to obtain crystalline and uncrystallized ethylene carbonate.
  • the uncrystallized ethylene carbonate enters the mother liquor tank through the first discharge line, and the uncrystallized in the mother liquor tank Ethylene carbonate enters the third rectification tank and the second rectification tank through the second discharge line in turn for rectification into the second product tank; the crystallization is heated and sweated in the falling film crystallizer, and the sweat obtained passes through the first outlet
  • the feed pipeline enters the sweat tank, and the sweat in the sweat tank enters the falling film crystallizer through the circulation pipeline; the remaining crystal after sweating melts and enters the first product tank.
  • a crystallization tube, a material circulation pump and a cooling system are installed inside the falling film crystallizer.
  • it further includes a first rectification tower, and the first rectification tower is connected to the falling film crystallizer.
  • the method for purifying electronic grade ethylene carbonate provided in this application is to seed crystals before cooling down and crystallize to provide seed crystals for crystallization, so that crystallization is easy to proceed, and the crystals are coated with fewer impurities, thereby improving the performance of electronic grade ethylene carbonate. Purity and yield. After seeding, cooling and crystallization are performed, and the difference in melting point is used to remove substances with boiling points similar to ethylene carbonate, azeotropes and heat-sensitive substances, which can effectively remove trace impurities, so that the impurity removal rate is high, and the single impurity content ⁇ 5ppm, to obtain high-purity ethylene carbonate, thereby effectively improving the performance of the electrolyte.
  • the primary crystallization yield of the purification method provided by the present application is 5% higher than that of Comparative Example 2, and the sweat output is small, so that the number of cycles of sweating is less and energy consumption is reduced.
  • the electronic grade ethylene carbonate prepared by the present application has less impurity content and small discoloration of the electronic grade ethylene carbonate, so that the battery life can be improved.
  • the uncrystallized mother liquor is enriched with a variety of impurities such as organic alcohols, aldehydes, ketones, which are close to the boiling point and properties of ethylene carbonate.
  • the uncrystallized mother liquor after cooling and crystallization is subjected to two rectifications, and impurities are further removed through rectification, and a second product with a purity greater than 99.99% is obtained from the second rectification tower.
  • the perspiration liquid is returned to the falling film crystallizer to recycle the raw material liquid and increase the total yield.
  • FIG. 1 is a schematic flow chart of a method for purifying electronic grade ethylene carbonate according to an embodiment of this application;
  • FIG. 2 is a schematic diagram of the structure of a purification device according to an embodiment of this application.
  • FIG. 3 is a schematic structural diagram of a purification device according to another embodiment of this application.
  • connection and “connected” should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral Ground connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication between two components.
  • connection should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral Ground connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication between two components.
  • a purification method of electronic grade ethylene carbonate includes the following steps:
  • step S4 The crystallization of step S3 is gradually raised to heat and sweat, and the obtained sweat is subjected to the next round of crystallization;
  • step S6 The uncrystallized mother liquor in step S3 is subjected to two rectifications to obtain a second product with a purity greater than 99.990%.
  • ethylene carbonate with a purity of 99.90% to 99.98% is seeded at 20-28°C, and the seeding is terminated when the temperature of the material drops to 31-32°C.
  • the temperature of the material drops to 31 ⁇ 32°C and crystallizes out, the heat of solidification will be released and the temperature will rebound. This rebound temperature is the final cooling temperature, and the seeding ends.
  • the source of the ethylene carbonate having a purity of 99.90% to 99.98% is not particularly limited.
  • the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain crude ethylene carbonate, and the crude product is flashed out of unreacted carbon dioxide through a flash tank. Then it enters the thin film evaporator, the gas phase is condensed and then enters the first rectification tower for rectification.
  • the feed rate during seeding is preferably 1.0 t/h to 5.0 t/h, more preferably 2.0 t/h.
  • the seeding temperature is preferably 25°C.
  • the quenching method is used for seeding under the condition of 20-28° C. to form seed crystals in the crystallizer, which is beneficial for the crystallization process to proceed on the seed crystals.
  • the temperature is raised to 36-37°C and then the temperature is kept constant.
  • the time from the temperature rise to the end of the constant temperature is 25-30 minutes.
  • seeding can crystallize the crude ethylene carbonate as the raw material.
  • the temperature is raised to 36-37° C. to melt the excess crystals, and a small amount of crystals are retained as seed crystals. Since the melting temperature of impurities is lower than the melting temperature of ethylene carbonate, the impurities melt faster in the process of melting the excess crystals, reducing the coating of impurities in the seed crystals, thereby improving the purity of the seed crystals and improving the purity of the seed crystals. Thereby the crystal purity is improved, and finally the purity of the first product is improved.
  • the cooling rate of the cooling crystallization is preferably 0.25-1.0°C/h, more preferably 0.5°C/h; the end temperature is preferably 32-34°C, more preferably 32°C; the crystallization time is preferably 5 ⁇ 20h, more preferably 10h; the constant temperature time is preferably 1h.
  • the crystals are heated and sweated by gradually increasing the temperature, and the obtained sweating liquid is subjected to the next round of crystallization, that is, the cooling crystallization in step S3 is performed.
  • the temperature increase rate of the temperature increase perspiration is preferably 3 to 5°C/h, more preferably 4°C/h; the end temperature is preferably 34 to 36.5°C, more preferably 35°C.
  • the purity of the sweat liquid obtained is 99.9910% to 99.9920%.
  • the next round of crystallization of the sweating fluid can make the material recycled and improve the utilization rate of the raw material.
  • the temperature is raised to melt the remaining crystals after sweating, and the first product with a purity greater than 99.995% is obtained.
  • the melting temperature of the crystal is preferably 40-50°C, more preferably 45°C.
  • the uncrystallized mother liquor is subjected to two rectifications to obtain a second product with a purity greater than 99.99%.
  • the purity of the mother liquor obtained after cooling and crystallization is 99.97 to 99.98%.
  • the degree of vacuum during the two rectifications is preferably -99.9 to -99.0 KPa, more preferably -99.9 Kpa, and the temperature is preferably 140 to 150°C, more preferably 145°C.
  • the judgment standard of the electronic grade ethylene carbonate adopts HG/T5391-2018 for evaluation.
  • FIG. 2 another embodiment of the present application provides a purification device used in the above-mentioned purification method, including a falling film crystallizer 3, a sweating liquid tank 4, a mother liquor tank 5, a first product tank 7, and a second product.
  • a purification device used in the above-mentioned purification method, including a falling film crystallizer 3, a sweating liquid tank 4, a mother liquor tank 5, a first product tank 7, and a second product.
  • Tank 8 the third rectification tower 6 and the second rectification tower 2;
  • the falling film crystallizer 3 is respectively connected to the inlets of the sweating liquid tank 4, the mother liquor tank 5 and the first product tank 7 through the first discharge line 31;
  • the sweat tank 4 is connected to the feed port of the falling film crystallizer 3 through a circulating pipeline 41;
  • the mother liquor tank 5 is connected to the third rectification tower 6 through the second discharge line 51;
  • the mother liquor tank 5, the third rectification tower 6, the second rectification tower 2 and the second product tank 8 are connected in sequence;
  • the raw material ethylene carbonate is first seeded and crystallized in the falling film crystallizer 3 to obtain crystallized and uncrystallized ethylene carbonate.
  • the uncrystallized ethylene carbonate enters the mother liquor tank 5 through the first discharge line 31.
  • the mother liquor tank The uncrystallized ethylene carbonate in 5 then enters the third rectification tower 6 and the second rectification tower 2 through the second discharge line 51 in turn for rectification and enters the second product tank 8; the crystallization is carried out in the falling film crystallizer 3.
  • the inside of the falling film crystallizer 3 is preferably installed with a crystallization tube, a plate heat exchanger, a material circulation pump and a cooling system.
  • the discharge pipeline of the falling film crystallizer 3 is preferably divided into three paths, the first path 311 is connected to the first product tank 7, the second path 312 is connected to the mother liquor tank 5, and the third path 313 is connected to The sweat tank 4 is connected.
  • the purification device preferably further includes a first rectification tower 1, and the first rectification tower 1 is connected to the falling film crystallizer 3, so that the ethylene carbonate obtained by the rectification of the first rectification tower 1
  • the crude product is fed from the side line of the first rectification tower 1 and fed from the top of the falling film crystallizer 3 for cooling and crystallization.
  • the purification device preferably further includes a buffer tank 9.
  • the buffer tank 9 is respectively connected to the falling film crystallizer 3 and the first product tank 7.
  • the product obtained after the crystallization of the sweating is melted is output from the falling film crystallizer 3 and preferably enters the buffer tank 9 for buffering, and then enters The first product tank 7.
  • the first purpose of setting up the buffer tank is to ensure that the crystalline product is qualified before entering the product tank, avoiding the product index fluctuations caused by unstable operation and polluting the product tank, and at the same time, the product after crystallization is injected into the buffer at one time
  • the tank, after passing the test is transferred to the product tank through the pump, which saves the total operating time of the crystallization process.
  • the inlet and outlet pipelines of a rectification tower 1 are all provided with valves for controlling the inlet and outlet of materials.
  • the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank
  • the unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
  • Seeding and cooling crystallization Under the protection of inert gas, take the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.98%) and add it from the top of the falling film crystallizer. The feed rate is 1.5t/h. After the feed is completed, the material circulation pump is turned on, the cooling system is turned on, and the cooling source at 20°C is used to stimulate the material to crystallize. When the temperature of the material drops to 31 ⁇ 32°C, it rebounds. The rebound temperature is After cooling to the final temperature, seeding is over.
  • the temperature control plate heat exchanger is switched, and the circulating water is quickly heated to 36°C by steaming, and the temperature is kept constant after the temperature is raised to 36°C.
  • the crystal is partially melted, leaving a small amount of crystal on the surface of the heat exchange tube as a seed crystal).
  • the material is crystallized in a crystallization tube with a gradual cooling method, and a crystal layer is formed on the wall of the crystallizer.
  • the cooling rate is 0.25°C/h
  • the end temperature of the cooling crystallization is 32°C
  • the crystallization time is 16h.
  • step (2) Warming up sweating: Melting the crystals of step (1) in a stepwise warming up sweating manner, the heating rate is 3°C/h, the end point temperature of sweating is 36°C, and the sweating liquid (purity of sweating liquid is 99.9910%) is discharged to Sweat in a tank.
  • the total yield of the entire purification method is determined to be 99%.
  • the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank
  • the unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
  • Seeding and cooling crystallization Under the protection of inert gas, take the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.95%) and add it from the top of the falling film crystallizer. The material rate is 2.0t/h. After the feeding is completed, the material circulation pump is turned on, the cooling system is turned on, and the 25°C cold source is used to stimulate the material to crystallize. When the material temperature reaches 31 ⁇ 32°C, the seeding will stop when the temperature rebounds.
  • the temperature control plate heat exchanger After seeding is over, switch the temperature control plate heat exchanger, and steam the circulating water to quickly heat up to 36.5°C, and then keep the temperature at 36.5°C (the time from the temperature rise to the end of the constant temperature is 25min. The excess crystals are partially melted, leaving a small amount of crystals on the surface of the heat exchange tube as seed crystals).
  • the material After the end of the constant temperature, the material is crystallized in a crystallization tube with a gradual cooling method, and a crystal layer is formed on the wall of the crystallizer.
  • the cooling rate is 0.5°C/h
  • the end temperature of the cooling crystallization is 32°C
  • the crystallization time is 9h
  • step (2) Warming up sweating: Melting the crystals of step (1) in a stepwise warming up sweating manner, the heating rate is 4°C/h, the end point temperature of sweating is 36.5°C, and the sweating fluid (purity of sweating fluid is 99.9920%) is discharged to Sweat in a tank.
  • the purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography.
  • the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank
  • the unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
  • Seeding and cooling crystallization Under the protection of inert gas, take part of the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.90%) and add it from the top of the falling film crystallizer. The feed rate is 5.0t/h. After the feed is completed, turn on the material circulation pump and turn on the cooling system. Use a 28°C cold source to stimulate the material to crystallize for 60 minutes. When the material temperature reaches 31-32°C, stop when the temperature rebounds. After crystal seeding is finished, switch the temperature control plate heat exchanger, and steam the circulating water to quickly heat up the circulating water to 36°C.
  • the temperature After the temperature is raised to 36°C, it will be kept at a constant temperature. Part of the excess crystals melted, leaving a small amount of crystals on the surface of the heat exchange tube as seed crystals).
  • the material After the end of the constant temperature, the material is crystallized in a crystallization tube with a gradual cooling method, and a crystal layer is formed on the wall of the crystallizer.
  • the cooling rate is 0.75°C/h
  • the end temperature of the cooling crystallization is 32°C
  • the crystallization time is 5.3h, and then the constant temperature is performed.
  • the constant temperature time is 3h to obtain crystallized and uncrystallized ethylene carbonate mother liquor (the purity of the uncrystallized ethylene carbonate mother liquor is 99.97%); the uncrystallized ethylene carbonate mother liquor is discharged from the crystallizer outlet and transported to the mother liquor tank, It enters the third distillation tower as a raw material.
  • step (2) Sweating at elevated temperature: Melt the crystals of step (1) by gradually heating up perspiration at a heating rate of 5°C/h and a sweating end temperature of 36.5°C.
  • the sweating fluid purity of sweating fluid is 99.9910%) is discharged to Sweat in a tank.
  • the purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography.
  • the specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 4.
  • the total yield of the entire purification method is determined to be 97%.
  • the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank
  • the unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
  • Seeding and cooling crystallization Under the protection of inert gas, take the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.98%) and add it from the top of the falling film crystallizer. The material rate is 1.0t/h. After the material is fed, the material circulation pump is turned on, the cooling system is turned on, and the 20°C cold source is used to stimulate the material to crystallize. When the material temperature drops to 31 ⁇ 32°C, it rebounds. The rebound temperature is After cooling to the final temperature, seeding is over. After seeding is finished, switch the temperature control plate heat exchanger, and steam the circulating water to quickly heat up the circulating water to 37°C.
  • the temperature After the temperature is raised to 37°C, the temperature will be kept constant (the time from the temperature rise to the end of the constant temperature is 30 minutes, and the explosion will cause excess The crystal is partially melted, leaving a small amount of crystal on the surface of the heat exchange tube as a seed crystal).
  • the material After the end of the constant temperature, the material is crystallized in a crystallization tube with a step-by-step cooling method, and a crystal layer is formed on the wall of the crystallizer.
  • the cooling rate is 0.25°C/h
  • the end temperature of the cooling crystallization is 33°C
  • the crystallization time is 16h, and then the constant temperature is performed.
  • step (2) Warming up sweating: Melting the crystals of step (1) in a stepwise warming up and sweating manner, the heating rate is 3°C/h, the end point temperature of sweating is 34°C, and the sweating fluid (purity of sweating fluid is 99.9912%) is discharged to Sweat in a tank.
  • the purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography.
  • the specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 5.
  • the total yield of the entire purification method is determined to be 97.5%.
  • the purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography.
  • the specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 6.
  • the total yield of the entire purification method is determined to be 96%
  • Example 2 From the comparison of Example 2 and Comparative Example 1, it can be seen that the purification method provided by the present invention can reduce the coating of impurities in the crystal, reduce the content of each impurity, and increase the purity of the seed crystal, thereby increasing the purity of the crystal. , Improve product purity and yield.
  • the raw materials to be purified are exactly the same as in Example 2, and they are all crude ethylene carbonate (crude ethylene carbonate with a mass fraction of 99.95%) produced from the side line of the first rectification tower. Purification is carried out using the operating method and conditions of Example 4 in patent CN107501230A. After rectification, the ethylene carbonate solution obtained at the bottom of the rectification tower is returned to the raw material tank and then the purification is stopped. Rate. At this time, the purity and yield of the products in the first product tank and the second product tank were determined by gas chromatography. The specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 7.
  • the yield of the first product (%) the mass of the first product after crystallization/the amount of feed
  • Second product yield (%) quality of rectified product/feed amount
  • Total yield total product quality/total feed.
  • Example 2 From the comparison of Example 2 and Comparative Example 2, it can be seen that the purification method provided by the present invention has a 5% higher yield than that of Comparative Example 2 during a single crystallization. Energy consumption, less impurity content, higher purity.
  • Example 1 To Chroma Example 1 ⁇ 5(Does not change color)
  • Example 2 ⁇ 5(Does not change color)
  • Example 3 ⁇ 5(Does not change color)
  • Example 4 ⁇ 5(Does not change color) Comparative example 1 15-20 (light pink) Comparative example 2 20 (light pink)

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Abstract

Disclosed are a purification method for electronic-grade ethylene carbonate, and a purification apparatus thereof. The method comprises the following steps: S1: seeding ethylene carbonate having a purity of 99.90%-99.98%; S2: heating to 36-37℃ after the seeding ends, and then maintaining a constant temperature for 0.5-3 h; S3: carrying out cooling and crystallization after the temperature maintenance ends; S4: carrying out heating and sweating on crystals in a gradual heating manner, and carrying out a next round of crystallization on an obtained sweating liquid; S5: after the sweating ends, heating to melt the crystals subjected to sweating to obtain a first product having a purity of 99.995% or more; and S6: rectifying a non-crystallized mother liquor twice to obtain a second product having a purity of 99.990% or more.

Description

电子级碳酸乙烯酯的纯化方法及纯化装置Purification method and purification device of electronic grade ethylene carbonate
METHOD AND DEVICE OF PURIFYING ELECTRONIC GRADE ETHYLENE CARBONATEMETHOD AND DEVICE OF PURIFYING ELECTRONIC GRADE ETHYLENE CARBONATE
本申请要求在2020年03月11日提交中国专利局、申请号为202010164468.X、发明名称为“电子级碳酸乙烯酯的纯化方法及其纯化装置”的中国专利申请的优先权,其全部内容通过引用结合在本申请中。This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on March 11, 2020, the application number is 202010164468.X, and the invention title is "Electronic Grade Ethylene Carbonate Purification Method and Purification Device", and its entire content Incorporated in this application by reference.
技术领域Technical field
本申请涉及电子级试剂的制备技术领域,具体涉及电子级碳酸乙烯酯的纯化方法及其纯化装置。This application relates to the technical field of preparation of electronic grade reagents, in particular to a purification method of electronic grade ethylene carbonate and a purification device thereof.
背景技术Background technique
碳酸乙烯酯,又名1,3-二氧戊环-2酮、碳酸乙撑酯、乙二醇碳酸酯,分子式C 3H 4O 3,简写作EC。碳酸乙烯酯是一种性能优良的有机溶剂和有机合成中间体,可应用于纺丝、医药、塑料加工等各种领域。在电容电池行业,碳酸乙烯酯和碳酸丙烯酯混合溶液具有较高的介电常数,可用作锂离子电池电解液。 Ethylene carbonate, also known as 1,3-dioxolane-2 ketone, ethylene carbonate, and ethylene glycol carbonate, has a molecular formula of C 3 H 4 O 3 and abbreviated as EC. Ethylene carbonate is an organic solvent and organic synthesis intermediate with excellent performance, which can be used in various fields such as spinning, medicine, and plastic processing. In the capacitor battery industry, the mixed solution of ethylene carbonate and propylene carbonate has a high dielectric constant and can be used as an electrolyte for lithium ion batteries.
近年来,随着新能源行业的蓬勃发展以及电子元件技术的不断进步,高纯度碳酸乙烯酯成为电子工业中重要有机溶剂,尤其在锂电池电解液的生产中尤为重要。由于电解液是锂电池的关键材料,电解液的性能取决于配方中各种溶剂的质量,高纯度碳酸乙烯酯的纯度、总醇含量、水含量、金属离子含量和其他单一杂质成分的含量将直接影响电解液产品的性能,进而影响电池的指标。因此,对于高纯度碳酸乙烯酯的质量要求也越来越高。In recent years, with the vigorous development of the new energy industry and the continuous advancement of electronic component technology, high-purity ethylene carbonate has become an important organic solvent in the electronics industry, especially in the production of lithium battery electrolyte. Since the electrolyte is the key material of lithium batteries, the performance of the electrolyte depends on the quality of various solvents in the formulation. The purity of high-purity ethylene carbonate, total alcohol content, water content, metal ion content and other single impurity components will be Directly affect the performance of the electrolyte product, and then affect the battery indicators. Therefore, the quality requirements for high-purity ethylene carbonate are getting higher and higher.
中国专利申请CN107629030A提供了一种降膜结晶制备电子级碳酸乙烯酯的方法。将碳酸乙烯酯原料从结晶器顶部加入,以一定流量在结晶器与碳酸乙烯酯原料储罐之间循环。以逐步降温方式进行结晶,将未结晶的碳酸乙烯酯残留液排出,输送至回收装置。以分步升温发汗方式熔化晶层,以一定的比例切割发汗液,发汗液和残留液回收送回结晶器。熔化料液返回原料储罐,重复进行二次降膜结晶,得到电子级碳酸乙烯酯。该方式可以制备纯度高于99.99%的碳酸乙烯酯,但需要二次降膜结晶,能耗高,且发汗液切割比例高,产品在进行一次结晶后收率较低。Chinese patent application CN107629030A provides a method for preparing electronic grade ethylene carbonate by falling film crystallization. The ethylene carbonate raw material is added from the top of the crystallizer and circulates between the crystallizer and the ethylene carbonate raw material storage tank at a certain flow rate. The crystallization is carried out in a gradual cooling mode, and the uncrystallized ethylene carbonate residual liquid is discharged and transported to the recovery device. The crystal layer is melted by a step-by-step heating and sweating method, and the sweating liquid is cut in a certain proportion, and the sweating liquid and the residual liquid are recovered and sent back to the crystallizer. The molten material liquid is returned to the raw material storage tank, and the second falling film crystallization is repeated to obtain electronic grade ethylene carbonate. This method can prepare ethylene carbonate with a purity higher than 99.99%, but requires secondary falling film crystallization, high energy consumption, high perspiration cutting ratio, and low yield after primary crystallization.
中国专利申请CN107501230A提供了一种结晶与精馏耦合制备电子级碳酸乙烯酯的装置及方法,该方法利用降膜结晶与精馏工艺相结合,将原料罐的原料连续输送至结晶器,通过冷却介质降温结晶至一定晶层厚度,停止进料,升温发汗,结晶后的发汗液收集后输送至精馏塔,塔顶产品进入第二产品罐,塔釜产品循环回结晶原料罐,发汗结束后的结晶熔化为液体输送至第一产品罐。该申请实现了原料液的循环利用,最终获得了含量99.99%以上的电子级碳酸乙烯酯产品。该方法进入结晶器分离提纯的杂质去除率低,为获得高纯度产品,残液和发汗液排料量大,导致一次结晶的收率低,得到的发汗液和残液需要进行多次循环结晶,能耗高。同时,由于反应过程中杂质去除率低,在有氧及高温状态下容易变色,在进入电解液产品中会导致电池的容量衰减,循环寿命降低。Chinese patent application CN107501230A provides a device and method for preparing electronic grade ethylene carbonate by coupling crystallization and distillation. The medium is cooled and crystallized to a certain thickness of the crystal layer, feeding is stopped, and the temperature is raised to sweat. The sweated liquid after crystallization is collected and transported to the rectification tower. The top product enters the second product tank, and the bottom product is recycled back to the crystallization raw material tank. After sweating is over The crystals are melted and transported to the first product tank as a liquid. This application realizes the recycling of the raw material liquid, and finally obtains the electronic grade ethylene carbonate product with a content of more than 99.99%. The method enters the crystallizer to separate and purify impurities with a low removal rate. In order to obtain high-purity products, the amount of residual liquid and sweating liquid is large, resulting in a low yield of one crystallization, and the obtained sweating liquid and residual liquid need to be repeatedly crystallized , High energy consumption. At the same time, due to the low impurity removal rate during the reaction process, it is easy to change color under oxygen and high temperature conditions. When entering the electrolyte product, the capacity of the battery will decrease and the cycle life will be reduced.
发明内容Summary of the invention
针对现有技术的不足,本申请提供了电子级碳酸乙烯酯的纯化方法及其纯化装置,具体方案如下:In view of the shortcomings of the prior art, this application provides a purification method and a purification device for electronic grade ethylene carbonate. The specific solutions are as follows:
一种电子级碳酸乙烯酯的纯化方法,包括如下步骤:A purification method of electronic grade ethylene carbonate includes the following steps:
S1:将纯度为99.90%~99.98%的碳酸乙烯酯在20~28℃的条件下引晶,当物料温度降低至31~32℃时结束引晶;S1: Seed ethylene carbonate with a purity of 99.90%~99.98% at 20~28℃, and finish seeding when the material temperature drops to 31~32℃;
S2:引晶结束后升温至36~37℃后进行恒温,从升温到恒温结束的时间为25~30min;S2: After seeding, the temperature is raised to 36~37℃ and then the temperature is kept constant. The time from the temperature rise to the end of the constant temperature is 25~30min;
S3:恒温结束后降温结晶,降温结晶完成后恒温0.5~3h,得到结晶和未结晶母液,将得到的结晶和未结晶母液分离;S3: Cool down and crystallize after the end of the constant temperature, and keep the temperature constant for 0.5 to 3 hours after the completion of the cooling and crystallization, to obtain the crystalline and non-crystallized mother liquor, and separate the obtained crystalline and non-crystallized mother liquor;
S4:将所述步骤S3的结晶采用逐步升温的方式进行升温发汗,将得到的发汗液进行下一轮结晶;S4: The crystallization of step S3 is gradually raised to heat and sweat, and the obtained sweat is subjected to the next round of crystallization;
S5:发汗结束后,升温使发汗后的结晶熔化,得到纯度大于99.995%的第一产品;S5: After the sweating is over, the temperature is raised to melt the crystals after sweating to obtain the first product with a purity greater than 99.995%;
S6:将所述步骤S3中的未结晶母液进行两次精馏,得到纯度大于99.990%的第二产品。S6: The uncrystallized mother liquor in step S3 is subjected to two rectifications to obtain a second product with a purity greater than 99.990%.
本申请一些实施例中,所述步骤S3中降温结晶的降温速率为0.25~1.0℃/h,终点温度为32~34℃,结晶时间为5~20h。In some embodiments of the present application, the cooling rate of cooling crystallization in step S3 is 0.25-1.0° C./h, the end temperature is 32-34° C., and the crystallization time is 5-20 h.
本申请一些实施例中,所述步骤S4中升温发汗的升温速率为3~5℃/h,终点温度为34~36.5℃。In some embodiments of the present application, the heating rate of heating and sweating in step S4 is 3 to 5°C/h, and the end temperature is 34 to 36.5°C.
本申请一些实施例中,所述步骤S5中结晶熔化的温度为40~50℃。In some embodiments of the present application, the crystal melting temperature in step S5 is 40-50°C.
本申请一些实施例中,所述步骤S1中引晶时的物料进料速率为1.0t/h~5.0t/h。In some embodiments of the present application, the material feed rate during seeding in step S1 is 1.0 t/h to 5.0 t/h.
本申请一些实施例中,所述步骤S6中两次精馏时的真空度分别为-99.9~-99.0KPa,温度分别为140~150℃。In some embodiments of the present application, the vacuum degree during the two rectifications in the step S6 is -99.9 to -99.0 KPa, and the temperature is 140 to 150° C., respectively.
本申请还提供了上述的纯化方法所采用的纯化装置,包括降膜结晶器、发汗液罐、母液罐、第一产品罐、第二产品罐、第三精馏塔和第二精馏塔;This application also provides the purification device used in the above-mentioned purification method, including a falling film crystallizer, a sweating liquid tank, a mother liquor tank, a first product tank, a second product tank, a third rectification tower, and a second rectification tower;
所述降膜结晶器通过第一出料管线分别与发汗液罐、母液罐和第一产品罐的进料口相连;The falling film crystallizer is respectively connected to the inlets of the sweating liquid tank, the mother liquid tank and the first product tank through the first discharge pipeline;
所述发汗液罐通过循环管线与降膜结晶器的进料口连接;The sweat tank is connected to the feed port of the falling film crystallizer through a circulating pipeline;
所述母液罐通过第二出料管线与第三精馏塔连接;The mother liquor tank is connected to the third rectification tower through a second discharge line;
所述母液罐、第三精馏塔、第二精馏塔和第二产品罐依次连接;The mother liquor tank, the third rectification tower, the second rectification tower and the second product tank are connected in sequence;
工作时,原料碳酸乙烯酯首先在降膜结晶器引晶和降温结晶,得到结晶和未结晶碳酸乙烯酯,未结晶碳酸乙烯酯通过第一出料管线进入母液罐中,母液罐中的未结晶碳酸乙烯酯通过第二出料管线依次进入第三精馏罐和第二精馏罐进行精馏进入第二产品罐;结晶在降膜结晶器中进行升温发汗,得到的发汗液通过第一出料管线进入发汗液罐,发汗液罐中的发汗液再通过循环管线进入降膜结晶器中;发汗后剩余的结晶熔化,进入第一产品罐。When working, the raw material ethylene carbonate is first seeded and crystallized in a falling film crystallizer to obtain crystalline and uncrystallized ethylene carbonate. The uncrystallized ethylene carbonate enters the mother liquor tank through the first discharge line, and the uncrystallized in the mother liquor tank Ethylene carbonate enters the third rectification tank and the second rectification tank through the second discharge line in turn for rectification into the second product tank; the crystallization is heated and sweated in the falling film crystallizer, and the sweat obtained passes through the first outlet The feed pipeline enters the sweat tank, and the sweat in the sweat tank enters the falling film crystallizer through the circulation pipeline; the remaining crystal after sweating melts and enters the first product tank.
本申请一些实施例中,所述降膜结晶器的内部安装有结晶管、物料循环泵和冷却系统。In some embodiments of the present application, a crystallization tube, a material circulation pump and a cooling system are installed inside the falling film crystallizer.
本申请一些实施例中,还包括第一精馏塔,所述第一精馏塔与降膜结晶器连接。In some embodiments of the application, it further includes a first rectification tower, and the first rectification tower is connected to the falling film crystallizer.
本申请相较于现有技术取得了以下技术效果:Compared with the prior art, this application has achieved the following technical effects:
本申请提供的电子级碳酸乙烯酯的纯化方法,在降温结晶前先引晶,提供结晶用晶种,使结晶易于进行,并使晶体中包覆杂质更少,从而提高电子级碳酸乙烯酯的纯度和收率。引晶后进行降温结晶,利用熔点的不同,脱除与碳酸乙烯酯沸点相近的物质、共沸物以及对热敏感的物质,可以有效脱除微量杂质,从而使杂质去除率高,单一杂质含量≤5ppm,得到高纯度的碳酸乙烯酯,从而有效提高电解液的性能。根据实施例2和对比例2比较可知,本申请提供的纯化方法一次结晶收率相较于对比例2高5%,发汗液排量少, 从而发汗液循环次数少,降低能耗。同时本申请制备的电子级碳酸乙烯酯杂质含量少,电子级碳酸乙烯酯变色小,从而可以提高电池寿命。降温结晶后未结晶母液中富集了多种与碳酸乙烯酯沸点和性质接近的有机醇、醛、酮等杂质。本申请将降温结晶后的未结晶母液进行两次精馏,通过精馏进一步脱除杂质,从第二精馏塔得到纯度大于99.99%的第二产品。同时将发汗液返回到降膜结晶器中,对原料液循环利用,提高总收率。The method for purifying electronic grade ethylene carbonate provided in this application is to seed crystals before cooling down and crystallize to provide seed crystals for crystallization, so that crystallization is easy to proceed, and the crystals are coated with fewer impurities, thereby improving the performance of electronic grade ethylene carbonate. Purity and yield. After seeding, cooling and crystallization are performed, and the difference in melting point is used to remove substances with boiling points similar to ethylene carbonate, azeotropes and heat-sensitive substances, which can effectively remove trace impurities, so that the impurity removal rate is high, and the single impurity content ≤5ppm, to obtain high-purity ethylene carbonate, thereby effectively improving the performance of the electrolyte. According to the comparison between Example 2 and Comparative Example 2, the primary crystallization yield of the purification method provided by the present application is 5% higher than that of Comparative Example 2, and the sweat output is small, so that the number of cycles of sweating is less and energy consumption is reduced. At the same time, the electronic grade ethylene carbonate prepared by the present application has less impurity content and small discoloration of the electronic grade ethylene carbonate, so that the battery life can be improved. After cooling and crystallization, the uncrystallized mother liquor is enriched with a variety of impurities such as organic alcohols, aldehydes, ketones, which are close to the boiling point and properties of ethylene carbonate. In this application, the uncrystallized mother liquor after cooling and crystallization is subjected to two rectifications, and impurities are further removed through rectification, and a second product with a purity greater than 99.99% is obtained from the second rectification tower. At the same time, the perspiration liquid is returned to the falling film crystallizer to recycle the raw material liquid and increase the total yield.
附图说明Description of the drawings
图1为本申请一种实施方式电子级碳酸乙烯酯的的纯化方法的流程示意图;FIG. 1 is a schematic flow chart of a method for purifying electronic grade ethylene carbonate according to an embodiment of this application;
图2为本申请一种实施方式的纯化装置的结构示意图;2 is a schematic diagram of the structure of a purification device according to an embodiment of this application;
图3为本申请另一种实施方式的纯化装置的结构示意图;FIG. 3 is a schematic structural diagram of a purification device according to another embodiment of this application;
其中1、第一精馏塔;2、第二精馏塔;3、降膜结晶器;31、第一出料管线;311、第一路;312、第二路;313、第三路;4、发汗液罐;41、循环管线;5、母液罐;51、第二出料管线;6、第三精馏塔;7、第一产品罐;8、第二产品罐;9、缓冲罐。1. The first distillation tower; 2. The second distillation tower; 3. The falling film crystallizer; 31. The first discharge pipeline; 311, the first route; 312, the second route; 313, the third route; 4. Sweat tank; 41. Circulation pipeline; 5. Mother liquor tank; 51. Second discharge pipeline; 6. Third rectification tower; 7. First product tank; 8. Second product tank; 9. Buffer tank .
具体实施方式Detailed ways
以下结合具体实施方式对本申请的技术方案进行详实的阐述,然而应当理解,在没有进一步叙述的情况下,一个实施方式中的元件、结构和特征也可以有益地结合到其他实施方式中。The technical solution of the present application will be described in detail below in combination with specific embodiments. However, it should be understood that without further description, elements, structures and features in one embodiment can also be beneficially combined into other embodiments.
值得理解的是,尽管附图可能示出了方法步骤的特定顺序,但是步骤的顺序可与所描绘的顺序不同。此外,可同时地或部分同时地执行两个或更多个步骤。这样的变型将取决于所选择的软件和硬件以及设计者选择。所有这 样的变型都在本公开的范围内。It should be understood that although the drawings may show a specific order of method steps, the order of steps may be different from the order depicted. In addition, two or more steps may be performed simultaneously or partially simultaneously. Such variants will depend on the software and hardware chosen and the designer's choice. All such variations are within the scope of this disclosure.
在本申请的描述中,需要理解的是,术语“第一”、“第二”等仅用于描述目的,而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此,限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个该特征。In the description of this application, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. . Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of these features.
在本申请的描述中,需要说明的是,除非另有明确的规定和限定,术语“相连”、“连接”应做广义理解,例如,可以是固定连接,也可以是可拆卸连接,或一体地连接;可以是直接相连,也可以通过中间媒介间接相连,可以是两个元件内部的连通。对于本领域的普通技术人员而言,可以具体情况理解上述术语在本申请中的具体含义。In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral Ground connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood under specific circumstances.
所述的实施方式仅仅是对本申请的优选实施方式进行描述,并非对本申请的范围进行限定,在不脱离本申请设计精神的前提下,本领域普通技术人员对本申请的技术方案作出的各种变形和改进,均应落入本申请权利要求书确定的保护范围内。The described implementations are merely descriptions of the preferred implementations of the application, and are not intended to limit the scope of the application. Without departing from the design spirit of the application, various modifications made by those of ordinary skill in the art to the technical solutions of the application All improvements and improvements shall fall within the scope of protection determined by the claims of this application.
如图1所示,为本申请一种实施方式的电子级碳酸乙烯酯的纯化方法,包括如下步骤:As shown in Fig. 1, a purification method of electronic grade ethylene carbonate according to an embodiment of this application includes the following steps:
S1:将纯度为99.90%~99.98%的碳酸乙烯酯在20~28℃的环境条件下引晶,当物料温度降低至31~32℃时结束引晶;S1: seeding ethylene carbonate with a purity of 99.90% to 99.98% under environmental conditions of 20 to 28°C, and ending the seeding when the temperature of the material drops to 31 to 32°C;
S2:引晶结束后升温至36~37℃后进行恒温,从升温到恒温结束的时间为25~30min;S2: After seeding, the temperature is raised to 36~37℃ and then the temperature is kept constant. The time from the temperature rise to the end of the constant temperature is 25~30min;
S3:恒温结束后降温结晶,降温结晶完成后恒温0.5~3h,得到结晶和未结晶母液,将得到的结晶和未结晶母液分离;S3: Cool down and crystallize after the end of the constant temperature, and keep the temperature constant for 0.5 to 3 hours after the completion of the cooling and crystallization, to obtain the crystalline and non-crystallized mother liquor, and separate the obtained crystalline and non-crystallized mother liquor;
S4:将所述步骤S3的结晶采用逐步升温的方式进行升温发汗,将得到 的发汗液进行下一轮结晶;S4: The crystallization of step S3 is gradually raised to heat and sweat, and the obtained sweat is subjected to the next round of crystallization;
S5:发汗结束后,升温使发汗后的结晶熔化,得到纯度大于99.995%的第一产品;S5: After the sweating is over, the temperature is raised to melt the crystals after sweating to obtain the first product with a purity greater than 99.995%;
S6:将所述步骤S3中的未结晶母液进行两次精馏,得到纯度大于99.990%的第二产品。S6: The uncrystallized mother liquor in step S3 is subjected to two rectifications to obtain a second product with a purity greater than 99.990%.
本申请将纯度为99.90%~99.98%的碳酸乙烯酯在20~28℃的条件下引晶,当物料温度降低至31~32℃时结束引晶。当物料温度降低至31~32℃结晶析出时,会释放凝固热,温度反弹,此反弹温度为冷却终温,引晶结束。本实施方式对所述纯度为99.90%~99.98%的碳酸乙烯酯的来源没有特殊限定。例如,所述纯度为99.90%~99.98%的碳酸乙烯酯是以环氧乙烷和二氧化碳为原料进行加成反应制备得到碳酸乙烯酯粗产物,粗产物经闪蒸罐闪蒸出未反应的二氧化碳后进入薄膜蒸发器,气相冷凝后进入第一精馏塔精馏后制备得到。在本实施方式中,所述引晶时的进料速率优选为1.0t/h~5.0t/h,更优选为2.0t/h。在本实施方式中,所述引晶的温度优选为25℃。在本实施方式中,在20~28℃的条件下采用急冷方式引晶,使结晶器内形成晶种,有利于结晶过程在晶种上进行。In this application, ethylene carbonate with a purity of 99.90% to 99.98% is seeded at 20-28°C, and the seeding is terminated when the temperature of the material drops to 31-32°C. When the temperature of the material drops to 31~32℃ and crystallizes out, the heat of solidification will be released and the temperature will rebound. This rebound temperature is the final cooling temperature, and the seeding ends. In this embodiment, the source of the ethylene carbonate having a purity of 99.90% to 99.98% is not particularly limited. For example, the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain crude ethylene carbonate, and the crude product is flashed out of unreacted carbon dioxide through a flash tank. Then it enters the thin film evaporator, the gas phase is condensed and then enters the first rectification tower for rectification. In this embodiment, the feed rate during seeding is preferably 1.0 t/h to 5.0 t/h, more preferably 2.0 t/h. In this embodiment, the seeding temperature is preferably 25°C. In this embodiment, the quenching method is used for seeding under the condition of 20-28° C. to form seed crystals in the crystallizer, which is beneficial for the crystallization process to proceed on the seed crystals.
引晶结束后,升温至36~37℃后进行恒温,从升温到恒温结束的时间为25~30min。在本实施方式中引晶可以使得原料碳酸乙烯酯粗品结晶,在得到结晶后再升温至36~37℃将过量晶体熔化,保留少量晶体作为晶种。由于杂质的熔化温度低于碳酸乙烯酯的熔化温度,在熔化过量晶体的过程中杂质熔化的更快,减少杂质在晶种中的包覆,从而提高了晶种的纯度,晶种纯度提高,从而提高结晶纯度,最终提高第一产品纯度。After seeding is completed, the temperature is raised to 36-37°C and then the temperature is kept constant. The time from the temperature rise to the end of the constant temperature is 25-30 minutes. In this embodiment, seeding can crystallize the crude ethylene carbonate as the raw material. After the crystals are obtained, the temperature is raised to 36-37° C. to melt the excess crystals, and a small amount of crystals are retained as seed crystals. Since the melting temperature of impurities is lower than the melting temperature of ethylene carbonate, the impurities melt faster in the process of melting the excess crystals, reducing the coating of impurities in the seed crystals, thereby improving the purity of the seed crystals and improving the purity of the seed crystals. Thereby the crystal purity is improved, and finally the purity of the first product is improved.
恒温结束后,进行降温结晶,降温结晶完成后恒温0.5~3h,将得到的结 晶和未结晶母液分离。在本实施方式中,所述降温结晶的降温速率优选为0.25~1.0℃/h,更优选为0.5℃/h;终点温度优选为32~34℃,更优选为32℃;结晶时间优选为5~20h,更优选为10h;恒温时间优选为1h。After the end of the constant temperature, cooling crystallization is performed, and after the cooling and crystallization is completed, the temperature is kept constant for 0.5 to 3 hours, and the obtained crystalline and uncrystallized mother liquor are separated. In this embodiment, the cooling rate of the cooling crystallization is preferably 0.25-1.0°C/h, more preferably 0.5°C/h; the end temperature is preferably 32-34°C, more preferably 32°C; the crystallization time is preferably 5 ~20h, more preferably 10h; the constant temperature time is preferably 1h.
得到结晶后,将所述结晶采用逐步升温的方式进行升温发汗,将得到的发汗液进行下一轮结晶,即进行步骤S3的降温结晶。在本实施方式中,所述升温发汗的升温速率优选为3~5℃/h,更优选为4℃/h;终点温度优选为34~36.5℃,更优选为35℃。在本实施方式中,得到的发汗液纯度为99.9910~99.9920%。在本实施方式中,将发汗液进行下一轮结晶可以使物料循环使用,提高了原料利用率。After the crystals are obtained, the crystals are heated and sweated by gradually increasing the temperature, and the obtained sweating liquid is subjected to the next round of crystallization, that is, the cooling crystallization in step S3 is performed. In this embodiment, the temperature increase rate of the temperature increase perspiration is preferably 3 to 5°C/h, more preferably 4°C/h; the end temperature is preferably 34 to 36.5°C, more preferably 35°C. In this embodiment, the purity of the sweat liquid obtained is 99.9910% to 99.9920%. In this embodiment, the next round of crystallization of the sweating fluid can make the material recycled and improve the utilization rate of the raw material.
发汗结束后,升温使发汗后剩余的结晶熔化,得到纯度大于99.995%的第一产品。在本发明中,所述结晶熔化的温度优选为40~50℃,更优选为45℃。After the sweating is over, the temperature is raised to melt the remaining crystals after sweating, and the first product with a purity greater than 99.995% is obtained. In the present invention, the melting temperature of the crystal is preferably 40-50°C, more preferably 45°C.
降温结晶,得到结晶和未结晶母液后,将未结晶母液进行两次精馏,得到纯度大于99.99%的第二产品。在本实施方式中,降温结晶后得到的母液纯度为99.97~99.98%。在本发明中,所述两次精馏时的真空度分别优选为-99.9~-99.0KPa,更优选为-99.9Kpa;温度分别优选为140~150℃,更优选为145℃。After cooling and crystallization to obtain crystalline and uncrystallized mother liquor, the uncrystallized mother liquor is subjected to two rectifications to obtain a second product with a purity greater than 99.99%. In this embodiment, the purity of the mother liquor obtained after cooling and crystallization is 99.97 to 99.98%. In the present invention, the degree of vacuum during the two rectifications is preferably -99.9 to -99.0 KPa, more preferably -99.9 Kpa, and the temperature is preferably 140 to 150°C, more preferably 145°C.
在本实施方式中,所述电子级碳酸乙烯酯的判定标准采用HG/T5391-2018进行评定。In this embodiment, the judgment standard of the electronic grade ethylene carbonate adopts HG/T5391-2018 for evaluation.
如图2所示,本申请另一种实施方式提供了上述的纯化方法所采用的纯化装置,包括降膜结晶器3、发汗液罐4、母液罐5、第一产品罐7、第二产品罐8、第三精馏塔6和第二精馏塔2;As shown in Figure 2, another embodiment of the present application provides a purification device used in the above-mentioned purification method, including a falling film crystallizer 3, a sweating liquid tank 4, a mother liquor tank 5, a first product tank 7, and a second product. Tank 8, the third rectification tower 6 and the second rectification tower 2;
所述降膜结晶器3通过第一出料管线31分别与发汗液罐4、母液罐5和第一产品罐7的进料口相连;The falling film crystallizer 3 is respectively connected to the inlets of the sweating liquid tank 4, the mother liquor tank 5 and the first product tank 7 through the first discharge line 31;
所述发汗液罐4通过循环管线41与降膜结晶器3的进料口连接;The sweat tank 4 is connected to the feed port of the falling film crystallizer 3 through a circulating pipeline 41;
所述母液罐5通过第二出料管线51与第三精馏塔6连接;The mother liquor tank 5 is connected to the third rectification tower 6 through the second discharge line 51;
所述母液罐5、第三精馏塔6、第二精馏塔2和第二产品罐8依次连接;The mother liquor tank 5, the third rectification tower 6, the second rectification tower 2 and the second product tank 8 are connected in sequence;
工作时,原料碳酸乙烯酯首先在降膜结晶器3进行引晶和降温结晶,得到结晶和未结晶碳酸乙烯酯,未结晶碳酸乙烯酯通过第一出料管线31进入母液罐5中,母液罐5中的未结晶碳酸乙烯酯再通过第二出料管线51依次进入第三精馏塔6和第二精馏塔2进行精馏进入第二产品罐8;结晶在降膜结晶器3中进行升温发汗,得到的发汗液通过第一出料管线31进入发汗液罐4,发汗液罐4中的发汗液再通过循环管线41进入降膜结晶器3中;发汗后剩余的结晶熔化,进入第一产品罐7。When working, the raw material ethylene carbonate is first seeded and crystallized in the falling film crystallizer 3 to obtain crystallized and uncrystallized ethylene carbonate. The uncrystallized ethylene carbonate enters the mother liquor tank 5 through the first discharge line 31. The mother liquor tank The uncrystallized ethylene carbonate in 5 then enters the third rectification tower 6 and the second rectification tower 2 through the second discharge line 51 in turn for rectification and enters the second product tank 8; the crystallization is carried out in the falling film crystallizer 3. Heat up and sweat, and the obtained sweat liquid enters the sweat liquid tank 4 through the first discharge line 31, and the sweat liquid in the sweat liquid tank 4 enters the falling film crystallizer 3 through the circulation line 41; the remaining crystal after sweating melts and enters the second A product tank 7.
在本实施方式中,所述降膜结晶器3的内部优选安装有结晶管、板式换热器、物料循环泵和冷却系统。在本实施方式中,所述降膜结晶器3的出料管线优选分为三路,第一路311与第一产品罐7相连,第二路312与母液罐5相连,第三路313与发汗液罐4相连。In this embodiment, the inside of the falling film crystallizer 3 is preferably installed with a crystallization tube, a plate heat exchanger, a material circulation pump and a cooling system. In this embodiment, the discharge pipeline of the falling film crystallizer 3 is preferably divided into three paths, the first path 311 is connected to the first product tank 7, the second path 312 is connected to the mother liquor tank 5, and the third path 313 is connected to The sweat tank 4 is connected.
在本实施方式中,所述纯化装置优选还包括第一精馏塔1,所述第一精馏塔1与降膜结晶器3连接,从而第一精馏塔1精馏得到的碳酸乙烯酯粗品从第一精馏塔1侧线输入,从降膜结晶器3的顶部加入进行降温结晶。在本实施方式中,在降膜结晶器3中加入原料时优选采用惰性气体保护。In this embodiment, the purification device preferably further includes a first rectification tower 1, and the first rectification tower 1 is connected to the falling film crystallizer 3, so that the ethylene carbonate obtained by the rectification of the first rectification tower 1 The crude product is fed from the side line of the first rectification tower 1 and fed from the top of the falling film crystallizer 3 for cooling and crystallization. In this embodiment, it is preferable to use inert gas protection when adding raw materials to the falling film crystallizer 3.
如图3所示,在本实施方式中,所述纯化装置优选还包括缓冲罐9。所述缓冲罐9分别与降膜结晶器3和第一产品罐7连接,发汗后剩余的结晶熔化后得到的产品从降膜结晶器3中输出后优选进入缓冲罐9进行缓冲后,再进入第一产品罐7。在本实施方式中,设置缓冲罐的目的一是为了保证结晶产品的各项指标合格后进产品罐,避免因操作不稳定造成产品指标波动而污染产 品罐,同时,结晶后产品一次性打入缓冲罐,化验合格后再通过泵转移到产品罐,节省结晶过程的总操作时间。As shown in FIG. 3, in this embodiment, the purification device preferably further includes a buffer tank 9. The buffer tank 9 is respectively connected to the falling film crystallizer 3 and the first product tank 7. The product obtained after the crystallization of the sweating is melted is output from the falling film crystallizer 3 and preferably enters the buffer tank 9 for buffering, and then enters The first product tank 7. In this embodiment, the first purpose of setting up the buffer tank is to ensure that the crystalline product is qualified before entering the product tank, avoiding the product index fluctuations caused by unstable operation and polluting the product tank, and at the same time, the product after crystallization is injected into the buffer at one time The tank, after passing the test, is transferred to the product tank through the pump, which saves the total operating time of the crystallization process.
在本实施方式中,所述降膜结晶器3、发汗液罐4、母液罐5、第一产品罐7、第二产品罐8、第三精馏塔6、第二精馏塔2和第一精馏塔1的进出料管线均设置有阀门,用于控制进出料。In this embodiment, the falling film crystallizer 3, the sweating liquid tank 4, the mother liquor tank 5, the first product tank 7, the second product tank 8, the third rectification tower 6, the second rectification tower 2 and the second rectification tower The inlet and outlet pipelines of a rectification tower 1 are all provided with valves for controlling the inlet and outlet of materials.
为了进一步说明本申请,下面结合实施例对本申请提供的技术方案进行详细地描述,但不能将它们理解为对本申请保护范围的限定。In order to further explain the present application, the technical solutions provided by the present application will be described in detail below in conjunction with embodiments, but they should not be understood as limiting the protection scope of the present application.
实施例1Example 1
在本实施例中,所述纯度为99.90%~99.98%的碳酸乙烯酯是以环氧乙烷和二氧化碳为原料进行加成反应制备得到碳酸乙烯酯粗产物,粗产物经闪蒸罐闪蒸出未反应的二氧化碳后进入薄膜蒸发器,气相冷凝后进入第一精馏塔精馏后制备得到。In this embodiment, the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank The unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
(1)引晶和降温结晶:在惰性气体保护下,取第一精馏塔侧线产出的碳酸乙烯酯粗品(质量分数为99.98%的碳酸乙烯酯粗品)从降膜结晶器顶部加入,进料速率为1.5t/h,进料完成后,开启物料循环泵,开启冷却系统,采用20℃的冷源,刺激物料起晶,当物料温度降低至31~32℃时反弹,此反弹温度为冷却终温,引晶结束。引晶结束后,切换温度控制板式换热器,并通蒸汽将循环水快速升温至36℃,升温到36℃后进行恒温(从升温到恒温结束这个过程的时间为25min,将爆发产生的过量晶体部分熔化,使换热管表面留有少量晶体作为晶种)。恒温结束后将物料在结晶管以逐步降温方式进行结晶,在结晶器壁上形成晶层,降温速率为0.25℃/h,降温结晶终点温度为32℃,结晶时间为16h,随后进行恒温,恒温时间1h,得到结晶和未结晶的碳酸乙烯酯母液(未结晶的碳酸乙烯酯母液的纯度为99.97%);将未结晶 的碳酸乙烯酯母液从结晶器出口排出,并输送至母液罐中,作为原料进入第三精馏塔。(1) Seeding and cooling crystallization: Under the protection of inert gas, take the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.98%) and add it from the top of the falling film crystallizer. The feed rate is 1.5t/h. After the feed is completed, the material circulation pump is turned on, the cooling system is turned on, and the cooling source at 20°C is used to stimulate the material to crystallize. When the temperature of the material drops to 31~32°C, it rebounds. The rebound temperature is After cooling to the final temperature, seeding is over. After seeding, the temperature control plate heat exchanger is switched, and the circulating water is quickly heated to 36°C by steaming, and the temperature is kept constant after the temperature is raised to 36°C. The crystal is partially melted, leaving a small amount of crystal on the surface of the heat exchange tube as a seed crystal). After the end of the constant temperature, the material is crystallized in a crystallization tube with a gradual cooling method, and a crystal layer is formed on the wall of the crystallizer. The cooling rate is 0.25°C/h, the end temperature of the cooling crystallization is 32°C, and the crystallization time is 16h. It takes 1h to obtain crystallized and uncrystallized ethylene carbonate mother liquor (the purity of the uncrystallized ethylene carbonate mother liquor is 99.97%); the uncrystallized ethylene carbonate mother liquor is discharged from the crystallizer outlet and transported to the mother liquor tank as The raw materials enter the third distillation tower.
(2)升温发汗:将步骤(1)的结晶以逐步升温发汗方式进行熔融,升温速率为3℃/h,发汗终点温度为36℃,将发汗液(发汗液的纯度为99.9910%)排出至发汗液罐中。(2) Warming up sweating: Melting the crystals of step (1) in a stepwise warming up sweating manner, the heating rate is 3°C/h, the end point temperature of sweating is 36°C, and the sweating liquid (purity of sweating liquid is 99.9910%) is discharged to Sweat in a tank.
(3)结晶熔化:发汗结束后,继续升高温度,使发汗后剩余的结晶全部熔化为液体(结晶熔化过程中的温度为40℃),产品从降膜结晶器底部排入至缓冲罐中,继而输送至第一产品罐。(3) Crystal melting: After sweating, continue to increase the temperature to melt all the crystals remaining after sweating into liquid (the temperature during crystal melting is 40°C), and the product is discharged from the bottom of the falling film crystallizer into the buffer tank , And then transported to the first product tank.
(4)精馏:采用减压连续精馏操作,母液罐中的物料输送至第三精馏塔中,塔内压力为-99.9Kpa,塔底温度为145℃,塔顶脱除轻组分杂质,塔釜脱除重组分杂质,侧线采出质量分数为99.97%的碳酸乙烯酯,输送至第二精馏塔精馏(塔内压力为-99.9Kpa,塔底温度为145℃),侧线得到第二产品,送入第二产品罐。(4) Distillation: using continuous distillation operation under reduced pressure, the material in the mother liquor tank is transported to the third rectification tower, the pressure inside the tower is -99.9Kpa, the temperature at the bottom of the tower is 145°C, and the light components are removed from the top of the tower. Impurities, heavy component impurities are removed from the bottom of the tower, and ethylene carbonate with a mass fraction of 99.97% is extracted from the side line and transported to the second rectification tower for rectification (the internal pressure is -99.9Kpa, and the bottom temperature is 145°C), the side line The second product is obtained and sent to the second product tank.
采用气相色谱测定第一产品罐和第二产品罐中产品的纯度、杂质种类及含量、收率,具体检测条件如表1所示,具体结果如表2所示。Gas chromatography was used to determine the purity, impurity type and content, and yield of the products in the first product tank and the second product tank. The specific detection conditions are shown in Table 1, and the specific results are shown in Table 2.
表1 气相色谱检测条件Table 1 Gas Chromatography Test Conditions
色谱柱型号Column model DB-1701,30m*0.53mm*0.5umDB-1701, 30m*0.53mm*0.5um
进样口Inlet 260℃260°C
检测器Detector 300℃300°C
柱箱程序升温Oven temperature program 90℃(0mim)→10℃/min→190℃(0min)→20℃/min→220℃(6min)90℃(0mim)→10℃/min→190℃(0min)→20℃/min→220℃(6min)
柱流量Column flow 1ml/min1ml/min
分流比Split ratio 50:150:1
表2 实施例1第一、二产品罐中产品质量评定结果Table 2 Product quality evaluation results of the first and second product cans in Example 1
 To 纯度(%)purity(%) 乙二醇(ppm)Ethylene glycol (ppm) 二乙二醇(ppm)Diethylene glycol (ppm) 收率(%)Yield (%)
第一产品First product 99.9969399.99693 3.13.1 00 7070
第二产品Second product 99.9911099.99110 5.05.0 15.015.0 7575
进一步在发汗液再次返回降膜结晶器中进行循环降温结晶后,测定整个纯化方法的总收率为99%。Further, after the sweat liquid is returned to the falling film crystallizer again for cyclic cooling and crystallization, the total yield of the entire purification method is determined to be 99%.
实施例2Example 2
在本实施例中,所述纯度为99.90%~99.98%的碳酸乙烯酯是以环氧乙烷和二氧化碳为原料进行加成反应制备得到碳酸乙烯酯粗产物,粗产物经闪蒸罐闪蒸出未反应的二氧化碳后进入薄膜蒸发器,气相冷凝后进入第一精馏塔精馏后制备得到。In this embodiment, the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank The unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
(1)引晶和降温结晶:在惰性气体保护下,取第一精馏塔侧线产出的碳酸乙烯酯粗品(质量分数为99.95%的碳酸乙烯酯粗品)从降膜结晶器顶部加入,进料速率为2.0t/h,进料完成后,开启物料循环泵,开启冷却系统,采用25℃的冷源,刺激物料起晶,当物料温度达到31~32℃时,温度反弹时停止引晶,引晶结束后,切换温度控制板式换热器,并通蒸汽将循环水快速升温至36.5℃,升温到36.5℃后进行恒温(从升温到恒温结束这个过程的时间为25min,将爆发产生的过量晶体部分熔化,使换热管表面留有少量晶体作为晶种)。恒温结束后将物料在结晶管以逐步降温方式进行结晶,在结晶器壁上形成晶层,降温速率为0.5℃/h,降温结晶终点温度为32℃,结晶时间为9h,随后进行恒温,恒温时间2h,得到结晶和未结晶的碳酸乙烯酯母液(未结晶的碳酸乙烯酯母液的纯度为99.98%);将未结晶的碳酸乙烯酯母液从结晶器出口排出,并输送至母液罐中,作为原料进入第三精馏塔。(1) Seeding and cooling crystallization: Under the protection of inert gas, take the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.95%) and add it from the top of the falling film crystallizer. The material rate is 2.0t/h. After the feeding is completed, the material circulation pump is turned on, the cooling system is turned on, and the 25℃ cold source is used to stimulate the material to crystallize. When the material temperature reaches 31~32℃, the seeding will stop when the temperature rebounds. After seeding is over, switch the temperature control plate heat exchanger, and steam the circulating water to quickly heat up to 36.5°C, and then keep the temperature at 36.5°C (the time from the temperature rise to the end of the constant temperature is 25min. The excess crystals are partially melted, leaving a small amount of crystals on the surface of the heat exchange tube as seed crystals). After the end of the constant temperature, the material is crystallized in a crystallization tube with a gradual cooling method, and a crystal layer is formed on the wall of the crystallizer. The cooling rate is 0.5°C/h, the end temperature of the cooling crystallization is 32°C, the crystallization time is 9h, and then the constant temperature is performed. It takes 2h to obtain crystallized and uncrystallized ethylene carbonate mother liquor (the purity of the uncrystallized ethylene carbonate mother liquor is 99.98%); the uncrystallized ethylene carbonate mother liquor is discharged from the crystallizer outlet and transported to the mother liquor tank as The raw materials enter the third distillation tower.
(2)升温发汗:将步骤(1)的结晶以逐步升温发汗方式进行熔融,升温速率为4℃/h,发汗终点温度为36.5℃,将发汗液(发汗液的纯度为99.9920%)排出至发汗液罐中。(2) Warming up sweating: Melting the crystals of step (1) in a stepwise warming up sweating manner, the heating rate is 4°C/h, the end point temperature of sweating is 36.5°C, and the sweating fluid (purity of sweating fluid is 99.9920%) is discharged to Sweat in a tank.
(3)结晶熔化:发汗结束后,继续升高温度,使发汗后剩余的结晶全部熔化为液体(结晶熔化过程中的温度为45℃),产品从降膜结晶器底部排入至缓冲罐中,继而输送至第一产品罐。第一产品罐中的碳酸乙烯酯纯度为99.9961%,乙二醇3.0ppm,二乙二醇2.5ppm。(3) Crystal melting: After sweating, continue to increase the temperature to melt all the crystals remaining after sweating into liquid (the temperature during crystal melting is 45°C), and the product is discharged from the bottom of the falling film crystallizer into the buffer tank , And then transported to the first product tank. The purity of ethylene carbonate in the first product tank is 99.9961%, ethylene glycol 3.0ppm, and diethylene glycol 2.5ppm.
(4)精馏:采用减压连续精馏操作,母液罐中的物料输送至第三精馏塔中,塔内压力为-99.5Kpa,塔底温度为147℃,塔顶脱除轻组分杂质,塔釜脱除重组分杂质,侧线采出质量分数为99.96%的碳酸乙烯酯,输送至第二精馏塔(塔内压力为-99.5Kpa,塔底温度为147℃),侧线得到第二产品,送入第二产品罐。(4) Distillation: using continuous distillation operation under reduced pressure, the material in the mother liquor tank is transported to the third rectification tower, the pressure inside the tower is -99.5Kpa, the temperature at the bottom of the tower is 147°C, and the light components are removed from the top of the tower. Impurities, heavy component impurities are removed from the bottom of the tower, and ethylene carbonate with a mass fraction of 99.96% is extracted from the side line and transported to the second rectification tower (internal pressure is -99.5Kpa, and the bottom temperature is 147°C). The second product is sent to the second product tank.
采用气相色谱检测测定第一产品罐和第二产品罐中产品的纯度、杂质种类及含量、收率,具体检测条件同实施例1表1所示,具体结果如表3所示。The purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography.
表3 实施例2第一、二产品罐中产品质量评定结果Table 3 Evaluation results of product quality in the first and second product cans of Example 2
 To 纯度(%)purity(%) 乙二醇(ppm)Ethylene glycol (ppm) 二乙二醇(ppm)Diethylene glycol (ppm) 收率(%)Yield (%)
第一产品First product 99.9961099.99610 3.03.0 2.52.5 6868
第二产品Second product 99.9910099.99100 6.06.0 13.013.0 7373
进一步在发汗液再次返回降膜结晶器中进行循环降温结晶后,测定整个纯化方法的总收率为98%。Further, after the sweating liquid was returned to the falling film crystallizer again for cyclic cooling and crystallization, the total yield of the entire purification method was determined to be 98%.
实施例3Example 3
在本实施例中,所述纯度为99.90%~99.98%的碳酸乙烯酯是以环氧乙烷和二氧化碳为原料进行加成反应制备得到碳酸乙烯酯粗产物,粗产物经闪蒸罐闪蒸出未反应的二氧化碳后进入薄膜蒸发器,气相冷凝后进入第一精馏塔精馏后制备得到。In this embodiment, the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank The unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
(1)引晶和降温结晶:在惰性气体保护下,取部分第一精馏塔侧线产出的碳酸乙烯酯粗品(质量分数为99.90%的碳酸乙烯酯粗品)从降膜结晶器顶 部加入,进料速率为5.0t/h,进料完成后,开启物料循环泵,开启冷却系统,采用28℃的冷源,刺激物料起晶60min,物料温度达到31~32℃时,温度反弹时停止引晶,引晶结束后,切换温度控制板式换热器,并通蒸汽将循环水快速升温至36℃,升温到36℃后进行恒温(从升温到恒温结束这个过程的时间为30min,将爆发产生的过量晶体部分熔化,使换热管表面留有少量晶体作为晶种)。恒温结束后将物料在结晶管以逐步降温方式进行结晶,在结晶器壁上形成晶层,降温速率为0.75℃/h,降温结晶终点温度为32℃,结晶时间为5.3h,随后进行恒温,恒温时间3h,得到结晶和未结晶的碳酸乙烯酯母液(未结晶的碳酸乙烯酯母液的纯度为99.97%);将未结晶的碳酸乙烯酯母液从结晶器出口排出,并输送至母液罐中,作为原料进入第三精馏塔。(1) Seeding and cooling crystallization: Under the protection of inert gas, take part of the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.90%) and add it from the top of the falling film crystallizer. The feed rate is 5.0t/h. After the feed is completed, turn on the material circulation pump and turn on the cooling system. Use a 28°C cold source to stimulate the material to crystallize for 60 minutes. When the material temperature reaches 31-32°C, stop when the temperature rebounds. After crystal seeding is finished, switch the temperature control plate heat exchanger, and steam the circulating water to quickly heat up the circulating water to 36°C. After the temperature is raised to 36°C, it will be kept at a constant temperature. Part of the excess crystals melted, leaving a small amount of crystals on the surface of the heat exchange tube as seed crystals). After the end of the constant temperature, the material is crystallized in a crystallization tube with a gradual cooling method, and a crystal layer is formed on the wall of the crystallizer. The cooling rate is 0.75°C/h, the end temperature of the cooling crystallization is 32°C, the crystallization time is 5.3h, and then the constant temperature is performed. The constant temperature time is 3h to obtain crystallized and uncrystallized ethylene carbonate mother liquor (the purity of the uncrystallized ethylene carbonate mother liquor is 99.97%); the uncrystallized ethylene carbonate mother liquor is discharged from the crystallizer outlet and transported to the mother liquor tank, It enters the third distillation tower as a raw material.
(2)升温发汗:将步骤(1)的结晶以逐步升温发汗方式进行熔融,升温速率为5℃/h,发汗终点温度为36.5℃,将发汗液(发汗液的纯度为99.9910%)排出至发汗液罐中。(2) Sweating at elevated temperature: Melt the crystals of step (1) by gradually heating up perspiration at a heating rate of 5°C/h and a sweating end temperature of 36.5°C. The sweating fluid (purity of sweating fluid is 99.9910%) is discharged to Sweat in a tank.
(3)结晶熔化:发汗结束后,继续升高温度,使发汗后剩余的结晶全部熔化为液体(结晶熔化过程中的温度为50℃),产品从降膜结晶器底部排入至缓冲罐中,继而输送至第一产品罐。(3) Crystal melting: After sweating, continue to increase the temperature to melt all the crystals remaining after sweating into liquid (the temperature during crystal melting is 50°C), and the product is discharged from the bottom of the falling film crystallizer into the buffer tank , And then transported to the first product tank.
(4)精馏:采用减压连续精馏操作,母液罐中的物料输送至第三精馏塔中,塔内压力为-99.5Kpa,塔底温度为148℃,塔顶脱除轻组分杂质,塔釜脱除重组分杂质,侧线采出质量分数为99.98%的碳酸乙烯酯,输送至第二精馏塔精馏(塔内压力为-99.5Kpa,塔底温度为148℃),侧线得到第二产品,送入第二产品罐。(4) Distillation: using continuous distillation operation under reduced pressure, the material in the mother liquor tank is transported to the third rectification tower, the pressure inside the tower is -99.5Kpa, the temperature at the bottom of the tower is 148°C, and the light components are removed from the top of the tower. Impurities, heavy component impurities are removed from the bottom of the tower, and ethylene carbonate with a mass fraction of 99.98% is extracted from the side line and transported to the second rectification tower for rectification (internal pressure is -99.5Kpa, and the bottom temperature is 148°C), side line The second product is obtained and sent to the second product tank.
采用气相色谱检测测定第一产品罐和第二产品罐中产品的纯度、杂质种类及含量、收率,具体检测条件同实施例1表1所示,具体结果如表4所示。The purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography. The specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 4.
表4 实施例3第一、二产品罐中产品质量评定结果Table 4 Evaluation results of product quality in the first and second product cans of Example 3
 To 纯度(%)purity(%) 乙二醇(ppm)Ethylene glycol (ppm) 二乙二醇(ppm)Diethylene glycol (ppm) 收率(%)Yield (%)
第一产品First product 99.9955099.99550 5.05.0 4.04.0 7272
第二产品Second product 99.9920099.99200 6.06.0 13.013.0 7373
进一步在发汗液再次返回降膜结晶器中进行循环降温结晶后,测定整个纯化方法的总收率为97%。Further, after the sweat liquid is returned to the falling film crystallizer again for cyclic cooling and crystallization, the total yield of the entire purification method is determined to be 97%.
实施例4Example 4
在本实施例中,所述纯度为99.90%~99.98%的碳酸乙烯酯是以环氧乙烷和二氧化碳为原料进行加成反应制备得到碳酸乙烯酯粗产物,粗产物经闪蒸罐闪蒸出未反应的二氧化碳后进入薄膜蒸发器,气相冷凝后进入第一精馏塔精馏后制备得到。In this embodiment, the ethylene carbonate with a purity of 99.90% to 99.98% is prepared by the addition reaction of ethylene oxide and carbon dioxide as raw materials to obtain a crude ethylene carbonate product, and the crude product is flashed out by a flash tank The unreacted carbon dioxide enters the thin film evaporator, the gas phase is condensed, and then enters the first distillation tower for rectification.
(1)引晶和降温结晶:在惰性气体保护下,取第一精馏塔侧线产出的碳酸乙烯酯粗品(质量分数为99.98%的碳酸乙烯酯粗品)从降膜结晶器顶部加入,进料速率为1.0t/h,进料完成后,开启物料循环泵,开启冷却系统,采用20℃的冷源,刺激物料起晶,当物料温度降低至31~32℃时反弹,此反弹温度为冷却终温,引晶结束。引晶结束后,切换温度控制板式换热器,并通蒸汽将循环水快速升温至37℃,升温到37℃后进行恒温(从升温到恒温结束这个过程的时间为30min,将爆发产生的过量晶体部分熔化,使换热管表面留有少量晶体作为晶种)。恒温结束后将物料在结晶管以逐步降温方式进行结晶,在结晶器壁上形成晶层,降温速率为0.25℃/h,降温结晶终点温度为33℃,结晶时间为16h,随后进行恒温,恒温时间0.5h,得到结晶和未结晶的碳酸乙烯酯母液(未结晶的碳酸乙烯酯母液的纯度为99.975%);将未结晶的碳酸乙烯酯母液从结晶器出口排出,并输送至母液罐中,作为原料进入第三精馏塔。(1) Seeding and cooling crystallization: Under the protection of inert gas, take the crude ethylene carbonate produced from the side line of the first rectification tower (the crude ethylene carbonate with a mass fraction of 99.98%) and add it from the top of the falling film crystallizer. The material rate is 1.0t/h. After the material is fed, the material circulation pump is turned on, the cooling system is turned on, and the 20℃ cold source is used to stimulate the material to crystallize. When the material temperature drops to 31~32℃, it rebounds. The rebound temperature is After cooling to the final temperature, seeding is over. After seeding is finished, switch the temperature control plate heat exchanger, and steam the circulating water to quickly heat up the circulating water to 37°C. After the temperature is raised to 37°C, the temperature will be kept constant (the time from the temperature rise to the end of the constant temperature is 30 minutes, and the explosion will cause excess The crystal is partially melted, leaving a small amount of crystal on the surface of the heat exchange tube as a seed crystal). After the end of the constant temperature, the material is crystallized in a crystallization tube with a step-by-step cooling method, and a crystal layer is formed on the wall of the crystallizer. The cooling rate is 0.25°C/h, the end temperature of the cooling crystallization is 33°C, the crystallization time is 16h, and then the constant temperature is performed. Time 0.5h to obtain crystallized and uncrystallized ethylene carbonate mother liquor (the purity of the uncrystallized ethylene carbonate mother liquor is 99.975%); discharge the uncrystallized ethylene carbonate mother liquor from the crystallizer outlet and transport it to the mother liquor tank, It enters the third distillation tower as a raw material.
(2)升温发汗:将步骤(1)的结晶以逐步升温发汗方式进行熔融,升温速率为3℃/h,发汗终点温度为34℃,将发汗液(发汗液的纯度为99.9912%)排出至发汗液罐中。(2) Warming up sweating: Melting the crystals of step (1) in a stepwise warming up and sweating manner, the heating rate is 3°C/h, the end point temperature of sweating is 34°C, and the sweating fluid (purity of sweating fluid is 99.9912%) is discharged to Sweat in a tank.
(3)结晶熔化:发汗结束后,继续升高温度,使发汗后剩余的结晶全部熔化为液体(结晶熔化过程中的温度为40℃),产品从降膜结晶器底部排入至缓冲罐中,继而输送至第一产品罐。(3) Crystal melting: After sweating, continue to increase the temperature to melt all the crystals remaining after sweating into liquid (the temperature during crystal melting is 40°C), and the product is discharged from the bottom of the falling film crystallizer into the buffer tank , And then transported to the first product tank.
(4)精馏:采用减压连续精馏操作,母液罐中的物料输送至第三精馏塔中,塔内压力为-99.0Kpa,塔底温度为140℃,塔顶脱除轻组分杂质,塔釜脱除重组分杂质,侧线采出质量分数为99.98%的碳酸乙烯酯,输送至第二精馏塔精馏(塔内压力为-99.0Kpa,塔底温度为150℃),侧线得到第二产品,送入第二产品罐。(4) Distillation: using continuous distillation operation under reduced pressure, the material in the mother liquor tank is transported to the third rectification tower, the pressure inside the tower is -99.0Kpa, the temperature at the bottom of the tower is 140°C, and the light components are removed from the top of the tower. Impurities, heavy component impurities are removed from the bottom of the tower, and ethylene carbonate with a mass fraction of 99.98% is extracted from the side line and transported to the second rectification tower for rectification (internal pressure is -99.0Kpa, and the temperature at the bottom of the tower is 150°C). The second product is obtained and sent to the second product tank.
采用气相色谱检测测定第一产品罐和第二产品罐中产品的纯度、杂质种类及含量、收率,具体检测条件同实施例1表1所示,具体结果如表5所示。The purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography. The specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 5.
表5 实施例4第一、二产品罐中产品质量评定结果Table 5 Evaluation results of product quality in the first and second product cans of Example 4
 To 纯度(%)purity(%) 乙二醇(ppm)Ethylene glycol (ppm) 二乙二醇(ppm)Diethylene glycol (ppm) 收率(%)Yield (%)
第一产品First product 99.9960099.99600 5.05.0 4.04.0 7070
第二产品Second product 99.9925099.99250 8.08.0 13.013.0 7373
进一步在发汗液再次返回降膜结晶器中进行循环降温结晶后,测定整个纯化方法的总收率为97.5%。Further, after the sweat liquid is returned to the falling film crystallizer again for cyclic cooling and crystallization, the total yield of the entire purification method is determined to be 97.5%.
对比例1Comparative example 1
除未引晶和晶引晶熔化的操作外,其他操作步骤与实施例2完全相同。Except for the operations of non-seeding and crystal seeding and melting, the other operation steps are exactly the same as those in the second embodiment.
采用气相色谱检测测定第一产品罐和第二产品罐中产品的纯度、杂质种类及含量、收率,具体检测条件同实施例1表1所示,具体结果如表6所示。The purity, impurity type and content, and yield of the products in the first product tank and the second product tank were determined by gas chromatography. The specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 6.
表6 对比例1第一、二产品罐中产品质量评定结果Table 6 The quality assessment results of the first and second product cans of Comparative Example 1
 To 纯度(%)purity(%) 乙二醇(ppm)Ethylene glycol (ppm) 二乙二醇(ppm)Diethylene glycol (ppm) 收率(%)Yield (%)
第一产品First product 99.9941099.99410 4.54.5 6.76.7 6565
第二产品Second product 99.9910099.99100 6.06.0 13.013.0 7373
进一步在发汗液再次返回降膜结晶器中进行循环降温结晶后,测定整个纯化方法的总收率为96%;Further, after the sweat liquid is returned to the falling film crystallizer again for cyclic cooling and crystallization, the total yield of the entire purification method is determined to be 96%;
由实施例2和对比例1进行对比可知,本发明提供的纯化方法,在降温结晶前进行引晶可以减少杂质在晶体中包覆,降低各杂质含量,提高晶种纯度,从而提高结晶的纯度,提高产品纯度和收率。From the comparison of Example 2 and Comparative Example 1, it can be seen that the purification method provided by the present invention can reduce the coating of impurities in the crystal, reduce the content of each impurity, and increase the purity of the seed crystal, thereby increasing the purity of the crystal. , Improve product purity and yield.
对比例2Comparative example 2
待纯化原料与实施例2完全相同,均是来自第一精馏塔侧线产出的碳酸乙烯酯粗品(质量分数为99.95%的碳酸乙烯酯粗品)。采用专利CN107501230A中实施例4的操作方法和条件进行纯化,在精馏后,精馏塔底得到的碳酸乙烯酯溶液送回至原料罐后停止纯化,仅检测待纯化原料进行一次结晶时的收率。此时,采用气相色谱检测测定第一产品罐和第二产品罐中产品的纯度和收率,具体检测条件同实施例1表1所示,具体结果如表7所示。The raw materials to be purified are exactly the same as in Example 2, and they are all crude ethylene carbonate (crude ethylene carbonate with a mass fraction of 99.95%) produced from the side line of the first rectification tower. Purification is carried out using the operating method and conditions of Example 4 in patent CN107501230A. After rectification, the ethylene carbonate solution obtained at the bottom of the rectification tower is returned to the raw material tank and then the purification is stopped. Rate. At this time, the purity and yield of the products in the first product tank and the second product tank were determined by gas chromatography. The specific detection conditions were the same as those shown in Table 1 of Example 1, and the specific results were shown in Table 7.
表7 对比例2第一、二产品罐中产品质量评定结果Table 7 The quality evaluation results of the first and second product cans of Comparative Example 2
 To 纯度(%)purity(%) 乙二醇(ppm)Ethylene glycol (ppm) 二乙二醇(ppm)Diethylene glycol (ppm) 收率(%)Yield (%)
第一产品First product 99.992199.9921 8.28.2 9.59.5 6363
第二产品Second product 99.991099.9910 6.06.0 13.013.0 7373
其中实施例1~4、对比例1~2中:Among them, in Examples 1 to 4 and Comparative Examples 1 to 2:
第一产品收率(%)=结晶后第一产品质量/进料量;The yield of the first product (%) = the mass of the first product after crystallization/the amount of feed;
第二产品收率(%)=精馏产品质量/进料量Second product yield (%) = quality of rectified product/feed amount
总收率=产品总质量/进料总量。Total yield = total product quality/total feed.
由实施例2和对比例2进行对比可知,本发明提供的纯化方法,在一次结晶时收率相较于对比例2高5%,发汗液排量少,从而发汗液循环次数少,从而降低能耗,且杂质含量更少,纯度更高。From the comparison of Example 2 and Comparative Example 2, it can be seen that the purification method provided by the present invention has a 5% higher yield than that of Comparative Example 2 during a single crystallization. Energy consumption, less impurity content, higher purity.
实施例5Example 5
将实施例1~3、对比例1和对比例2中的第一产品罐中的结晶产品分别与锂电池电解液混合,混合均匀后,转移到60℃恒温箱中保存,测定24小时的色度。其中,色度检测采用色度仪检测方法,Pt-Co色号。具体结果如表8和所示。The crystalline product in the first product tank in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 was mixed with the lithium battery electrolyte, and after mixing uniformly, it was transferred to a 60°C incubator for storage, and the color was measured for 24 hours. Spend. Among them, the chromaticity detection adopts the colorimeter detection method, Pt-Co color number. The specific results are shown in Table 8.
表8 变色反应结果Table 8 Discoloration reaction results
 To 色度Chroma
实施例1Example 1 <5(不变色)<5(Does not change color)
实施例2Example 2 <5(不变色)<5(Does not change color)
实施例3Example 3 <5(不变色)<5(Does not change color)
实施例4Example 4 <5(不变色)<5(Does not change color)
对比例1Comparative example 1 15-20(淡粉色)15-20 (light pink)
对比例2Comparative example 2 20(淡粉色)20 (light pink)
由表8可以看出,本发明纯化得到的电子级碳酸乙烯酯变色小,结果表明,本发明纯化后的碳酸乙烯酯纯度高,杂质含量少,从而可以提高电池寿命。It can be seen from Table 8 that the electronic grade ethylene carbonate purified by the present invention has little discoloration. The results show that the purified ethylene carbonate of the present invention has high purity and low impurity content, thereby improving battery life.
以上所述仅是本发明的优选实施方式,应当指出,对于本技术领域的普通技术人员来说,在不脱离本发明原理的前提下,还可以做出若干改进和润饰,这些改进和润饰也应视为本发明的保护范围。The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also It should be regarded as the protection scope of the present invention.

Claims (10)

  1. 电子级碳酸乙烯酯的纯化方法,其特征在于,包括如下步骤:The purification method of electronic grade ethylene carbonate is characterized in that it comprises the following steps:
    S1:将纯度为99.90%~99.98%的碳酸乙烯酯在20~28℃的条件下引晶,当物料温度降低至31~32℃时结束引晶;S1: Seed ethylene carbonate with a purity of 99.90%~99.98% at 20~28℃, and finish seeding when the material temperature drops to 31~32℃;
    S2:引晶结束后升温至36~37℃后进行恒温,从升温到恒温结束的时间为25~30min;S2: After seeding, the temperature is raised to 36~37℃ and then the temperature is kept constant. The time from the temperature rise to the end of the constant temperature is 25~30min;
    S3:恒温结束后降温结晶,降温结晶完成后恒温0.5~3h,得到结晶和未结晶母液,将得到的结晶和未结晶母液分离;S3: Cool down and crystallize after the end of the constant temperature, and keep the temperature constant for 0.5 to 3 hours after the completion of the cooling and crystallization, to obtain the crystalline and non-crystallized mother liquor, and separate the obtained crystalline and non-crystallized mother liquor;
    S4:将所述步骤S3的结晶采用逐步升温的方式进行升温发汗,将得到的发汗液进行下一轮结晶;S4: The crystallization of step S3 is gradually raised to heat and sweat, and the obtained sweat is subjected to the next round of crystallization;
    S5:发汗结束后,升温使发汗后的结晶熔化,得到纯度大于99.995%的第一产品;S5: After the sweating is over, the temperature is raised to melt the crystals after sweating to obtain the first product with a purity greater than 99.995%;
    S6:将所述步骤S3中的未结晶母液进行两次精馏,得到纯度大于99.990%的第二产品。S6: The uncrystallized mother liquor in step S3 is subjected to two rectifications to obtain a second product with a purity greater than 99.990%.
  2. 根据权利要求1所述的纯化方法,其特征在于,所述步骤S3中降温结晶的降温速率为0.25~1.0℃/h,终点温度为32~34℃,结晶时间为5~20h。The purification method according to claim 1, wherein the cooling rate of the cooling crystallization in step S3 is 0.25-1.0°C/h, the end temperature is 32-34°C, and the crystallization time is 5-20h.
  3. 根据权利要求1所述的纯化方法,其特征在于,所述步骤S4中升温发汗的升温速率为3~5℃/h,终点温度为34~36.5℃。The purification method according to claim 1, characterized in that the heating rate of heating and sweating in step S4 is 3 to 5°C/h, and the end temperature is 34 to 36.5°C.
  4. 根据权利要求1所述的纯化方法,其特征在于,所述步骤S5中结晶熔化的温度为40~50℃。The purification method according to claim 1, wherein the temperature of crystal melting in the step S5 is 40-50°C.
  5. 根据权利要求1所述的纯化方法,其特征在于,所述步骤S1中引晶时的进料速率为1.0t/h~5.0t/h。The purification method according to claim 1, wherein the feeding rate during seeding in the step S1 is 1.0 t/h to 5.0 t/h.
  6. 根据权利要求1所述的纯化方法,其特征在于,所述步骤S6中两次 精馏时的真空度分别为-99.9~-99.0KPa,温度分别为140~150℃。The purification method according to claim 1, wherein the vacuum degree during the two rectifications in the step S6 is -99.9~-99.0KPa, and the temperature is 140~150°C, respectively.
  7. 权利要求1~6任意一项所述的纯化方法的纯化装置,其特征在于,包括降膜结晶器、发汗液罐、母液罐、第一产品罐、第二产品罐、第三精馏塔和第二精馏塔;The purification device of the purification method according to any one of claims 1 to 6, characterized in that it comprises a falling film crystallizer, a sweating liquid tank, a mother liquor tank, a first product tank, a second product tank, a third rectification tower and The second distillation tower;
    所述降膜结晶器通过第一出料管线分别与发汗液罐、母液罐和第一产品罐的进料口相连;The falling film crystallizer is respectively connected to the inlets of the sweating liquid tank, the mother liquid tank and the first product tank through the first discharge pipeline;
    所述发汗液罐通过循环管线与降膜结晶器的进料口连接;The sweat tank is connected to the feed port of the falling film crystallizer through a circulating pipeline;
    所述母液罐通过第二出料管线与第三精馏塔连接;The mother liquor tank is connected to the third rectification tower through a second discharge line;
    所述母液罐、第三精馏塔、第二精馏塔和第二产品罐依次连接;The mother liquor tank, the third rectification tower, the second rectification tower and the second product tank are connected in sequence;
    工作时,原料碳酸乙烯酯首先在降膜结晶器引晶和降温结晶,得到结晶和未结晶碳酸乙烯酯,未结晶碳酸乙烯酯通过第一出料管线进入母液罐中,母液罐中的未结晶碳酸乙烯酯再通过第二出料管线依次进入第三精馏塔和第二精馏塔进行精馏进入第二产品罐;结晶在降膜结晶器中进行升温发汗,得到的发汗液通过第一出料管线进入发汗液罐,发汗液罐中的发汗液再通过循环管线进入降膜结晶器中;发汗后剩余的结晶熔化,进入第一产品罐。When working, the raw material ethylene carbonate is first seeded and crystallized in the falling film crystallizer to obtain crystallized and uncrystallized ethylene carbonate. The uncrystallized ethylene carbonate enters the mother liquor tank through the first discharge line, and the uncrystallized in the mother liquor tank Ethylene carbonate then enters the third rectification tower and the second rectification tower in turn through the second discharge line for rectification into the second product tank; the crystallization is heated and sweated in the falling film crystallizer, and the sweat obtained passes through the first The discharge pipeline enters the sweating liquid tank, and the sweating liquid in the sweating liquid tank enters the falling film crystallizer through the circulation pipeline; the remaining crystal after sweating melts and enters the first product tank.
  8. 根据权利要求7所述的纯化装置,其特征在于,所述降膜结晶器的内部安装有结晶管、物料循环泵和冷却系统。The purification device according to claim 7, characterized in that, a crystallization tube, a material circulation pump and a cooling system are installed inside the falling film crystallizer.
  9. 根据权利要求7所述的纯化装置,其特征在于,还包括第一精馏塔,所述第一精馏塔与降膜结晶器连接。8. The purification device according to claim 7, further comprising a first rectification tower connected to the falling film crystallizer.
  10. 根据权利要求7所述的纯化装置,其特征在于,所述降膜结晶器的出料管线优选分为三路,第一路与所述第一产品罐相连,第二路与所述母液罐相连,第三路与所述发汗液罐相连。The purification device according to claim 7, wherein the discharge pipeline of the falling film crystallizer is preferably divided into three paths, the first path is connected to the first product tank, and the second path is connected to the mother liquor tank. Connected, and the third way is connected to the sweat tank.
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