CN217828946U - Melting crystallization system for producing fluoroethylene carbonate - Google Patents

Abstract

The present application provides a melt crystallization system for producing fluoroethylene carbonate, comprising: the system comprises a primary melting crystallizer, a secondary melting crystallizer, a raw material storage tank, a mother liquor storage tank, a crude product tank, a finished product tank, a primary cooling and heating integrated machine, a secondary cooling and heating integrated machine, a first pressurizing device and a second pressurizing device. The primary melting crystallizer is respectively connected with the raw material storage tank, the mother solution storage tank, the crude product tank, the primary cooling and heating all-in-one machine and the first pressurizing device. The second-stage melting crystallizer is respectively connected with the mother liquor storage tank, the crude product tank, the finished product tank, the second-stage cooling and heating all-in-one machine and the second pressurizing device. The crude product tank is connected with the secondary melting crystallizer through a crude product conveying pipeline, and an outlet of the mother liquor storage tank is connected with a residual liquid conveying pipeline. The included angle alpha between the cross section direction of a plurality of heat transfer plates in the first-stage melting crystallizer and the second-stage melting crystallizer and the vertical direction is 0-10 degrees. The method improves the purity and the yield of the fluoroethylene carbonate product, reduces the production energy consumption and saves the production cost.

Description

Melting crystallization system for producing fluoroethylene carbonate

Technical Field

The application relates to the technical field of chemical equipment, in particular to a melting crystallization system for producing fluoroethylene carbonate.

Background

With the development of information technology, electronic products tend to be developed in the directions of small size, ultra-thin and convenient carrying, and lithium batteries are used as the best power supply source, and the requirements on the lithium batteries are gradually increased. In recent years, many researchers have focused on research in the fields of electrodes, electrolytes, separators, and the like of lithium batteries. The fluoroethylene carbonate is an important lithium ion battery electrolyte additive and is concerned by scientific researchers. The fluoroethylene carbonate can form a layer of protective film on the surface of the carbon electrode, and the formed protective film has a compact structure without increasing impedance, so that the carbon electrode is protected, the further decomposition of the electrolyte is inhibited, the low-temperature performance of the electrolyte is improved, and the cycle period and the battery performance of the lithium battery are obviously improved.

In recent years, the process for producing fluoroethylene carbonate has been problematic in that purification and separation are difficult, and impurities (difluoroethylene carbonate) produced in the process for producing fluoroethylene carbonate have boiling points very close to those of fluoroethylene carbonate. At present, the fluoroethylene carbonate is purified by a rectification method, and can reach the purity of more than 99.95 percent only by rectifying for 3-4 times before and after the purification, so that the product yield is low, and the energy consumption is high.

SUMMERY OF THE UTILITY MODEL

The application provides a melting crystallization system for producing fluoroethylene carbonate, which is used for solving the problems of high energy consumption and low purification efficiency in the prior art.

The present application provides a melt crystallization system for producing fluoroethylene carbonate, comprising: the system comprises a primary melting crystallizer, a secondary melting crystallizer, a raw material storage tank, a mother liquor storage tank, a crude product tank, a finished product tank, a primary cooling and heating integrated machine, a secondary cooling and heating integrated machine, a first pressurizing device and a second pressurizing device.

The discharge port of the primary melting crystallizer is respectively connected with a raw material storage tank, a mother liquor storage tank and a crude product tank; the primary melting crystallizer is also respectively connected with the primary cooling and heating integrated machine and the first pressure device.

The discharge port of the secondary melting crystallizer is respectively connected with a mother liquor storage tank, a crude product tank and a finished product tank; the secondary melting crystallizer is also respectively connected with the secondary cooling and heating all-in-one machine and the second pressurizing device.

The outlet of the crude product tank is connected with the secondary melting crystallizer through a crude product conveying pipeline, and the outlet of the mother liquor storage tank is connected with a residual liquid conveying pipeline.

The first-stage melting crystallizer and the second-stage melting crystallizer both adopt static plate-type melting crystallizers, the included angle alpha between the cross section direction of a plurality of heat transfer plates in the static plate-type melting crystallizers and the vertical direction is 0-10 degrees, the adjacent heat transfer plates form plate tubes, and first thermometers are arranged in the first-stage melting crystallizer and the second-stage melting crystallizer.

Optionally, baffle plates are arranged in the plurality of plate tubes, and the baffle plates are rectangular or wavy.

Optionally, the first pressurizing device and the second pressurizing device have the same structure, and the first pressurizing device comprises a nitrogen conveying pipeline, a nitrogen storage tank, a gas pressure regulator and a gas heat exchanger;

a gas heat exchanger is connected between the nitrogen conveying pipeline and the nitrogen storage tank, and a gas pressure regulator is arranged between the nitrogen storage tank and the primary melting crystallizer.

Optionally, the gas heat exchanger is provided with a cold and hot medium inlet and a cold and hot medium outlet.

Optionally, a second thermometer is disposed on the nitrogen storage tank.

Optionally, the outlet of the mother liquor storage tank is connected with the raw material storage tank through a mother liquor conveying pipeline.

Optionally, the melt crystallization system is further provided with a controller;

the controller is respectively connected with the first thermometer, the second thermometer, the air pressure regulator, the first-stage cold-hot all-in-one machine and the second-stage cold-hot all-in-one machine.

Optionally, the bottom plates of the primary melting crystallizer and the secondary melting crystallizer are obliquely arranged, and the included angle between the bottom plate and the horizontal direction is 5-10 degrees.

The application provides a production fluoroethylene carbonate's melting crystallization system has realized the two-stage melting crystallization to fluoroethylene carbonate, has improved the purity of product fluoroethylene carbonate, compares in prior art, has following beneficial effect:

(1) Through setting up pressure device and letting in certain pressure to the melting crystallizer in, not only can be fast with mother liquor or sweat with the crystalline solid separation under the effect of pressure like this, can make mother liquor or sweat with the crystalline solid more thorough that separates moreover, make the fluoroethylene carbonate crystal yield and the purity that the melting crystallization was handled higher.

(2) The included angle alpha between the cross section direction of the heat transfer plate and the vertical direction is 0-10 degrees, the bearing capacity of crystals accumulated on the heat transfer plate to pressure is improved, and the flow guide effect on discharged mother liquor or perspiration is achieved. Simultaneously, the device has synergistic action with a pressurizing device, is beneficial to the discharge of mother liquor or sweat, ensures that the purification efficiency is higher, avoids the discharge of crystals along with the impact of the mother liquor or the sweat, and avoids the loss of the crystals.

(3) The mother liquor in the mother liquor storage tank is conveyed to the raw material storage tank through the mother liquor conveying pipeline for secondary purification, so that the waste of the fluoroethylene carbonate can be reduced, and the yield of the fluoroethylene carbonate is greatly improved.

(4) The melting crystallization system is simple in structure and convenient to operate, the purity of the fluoroethylene carbonate can reach more than 99.9% of an electronic grade only by two-stage melting crystallization, and compared with the prior art that the fluoroethylene carbonate is purified by 3-4 times of rectification, the melting crystallization system has the advantages that the energy consumption is greatly reduced, and the production cost is saved.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following descriptions are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of a melt crystallization system for producing fluoroethylene carbonate according to an embodiment of the present application;

fig. 2 is a schematic front view of a heat transfer plate and a plate tube inside a static plate type melt crystallizer according to an embodiment of the present application;

FIG. 3 is a schematic diagram illustrating a left side structure of an internal baffle of a plate tube according to an embodiment of the present application;

FIG. 4 is a schematic diagram of a melt crystallization system for producing fluoroethylene carbonate according to another embodiment of the present application.

Description of reference numerals:

110: a first-stage melt crystallizer;

1101: a heat transfer plate;

1102: a first thermometer;

120: a secondary melt crystallizer;

130: a plate pipe;

1301: a baffle plate;

210: a raw material storage tank;

220: a mother liquor storage tank;

230: a crude product tank;

240: a finished product tank;

310: a first-stage cold and hot all-in-one machine;

320: a second-stage cold and hot integrated machine;

4: a first pressurizing device;

410: a nitrogen gas delivery line;

420: a nitrogen storage tank;

4201: a second thermometer;

430: a pressure regulator;

440: a gas heat exchanger;

4401: a cold and hot medium inlet;

4402: a cold and hot medium outlet;

5: a second pressurizing device;

610: a crude product conveying pipeline;

620: a raffinate transfer line;

630: a mother liquor delivery line;

710: and a controller.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described below, and it is obvious that the described embodiments are a part of the embodiments of the present application, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Fig. 1 is a schematic structural diagram of a melt crystallization system for producing fluoroethylene carbonate according to an embodiment of the present invention, and fig. 2 is a schematic structural diagram of a front surface of a heat transfer plate and a plate tube inside a static plate-type melt crystallizer according to an embodiment of the present invention, as shown in fig. 1 and fig. 2, the present invention provides a melt crystallization system for producing fluoroethylene carbonate, including: the system comprises a primary melt crystallizer 110, a secondary melt crystallizer 120, a raw material storage tank 210, a mother liquor storage tank 220, a crude product tank 230, a finished product tank 240, a primary cooling and heating integrated machine 310, a secondary cooling and heating integrated machine 320, a first pressurizing device 4 and a second pressurizing device 5.

The discharge port of the primary melt crystallizer 110 is respectively connected with a raw material storage tank 210, a mother liquor storage tank 220 and a crude product tank 230; the primary melt crystallizer 110 is also connected with the primary cooling and heating integrated machine 310 and the first pressurizing device 4 respectively.

The discharge port of the secondary melt crystallizer 120 is respectively connected with a mother liquor storage tank 220, a crude product tank 230 and a finished product tank 240; the secondary melt crystallizer 120 is also connected to the secondary cooling and heating integrated machine 320 and the second pressurizing device 5, respectively.

The outlet of the crude product tank 230 is connected with the secondary melt crystallizer 120 through a crude product conveying pipeline 610, and the outlet of the mother liquor storage tank 220 is connected with a raffinate conveying pipeline 620.

The primary melting crystallizer 110 and the secondary melting crystallizer 120 both adopt static plate type melting crystallizers, the included angle alpha between the cross section direction of a plurality of heat transfer plates 1101 in the static plate type melting crystallizers and the vertical direction is 0-10 degrees, the adjacent heat transfer plates 1101 form plate tubes 130, and first thermometers 1102 are arranged in the primary melting crystallizer 110 and the secondary melting crystallizer 120.

Specifically, the working fluid to be purified containing fluoroethylene carbonate from the fluoroethylene carbonate production step is transferred to and stored in the raw material tank 210 as a raw material fluid containing difluoroethylene carbonate, chloroethylene carbonate and other impurities from the production step in addition to the fluoroethylene carbonate product. The fluoroethylene carbonate is purified by utilizing the different melting points of the fluoroethylene carbonate and impurities and sequentially carrying out the processes of cooling crystallization, heating sweating and melting on the raw material liquid. The primary melting crystallizer 110 and the secondary melting crystallizer 120 both adopt static plate type melting crystallizers, a plurality of heat transfer plates 1101 are arranged in parallel in the crystallizers, the adjacent heat transfer plates 1101 form plate pipes 130, a cooling medium circulates in the plate pipes 130, a raw material liquid crystallizes outside the plate pipes 130 and accumulates on the outer walls of the plate pipes 130, and the static plate type melting crystallizers are simple to operate, low in operation cost and good in heat exchange effect.

The raw material liquid in the raw material storage tank 210 is conveyed to the primary melting crystallizer 110 for purification, the primary melting crystallizer 110 is cooled through the primary cooling and heating all-in-one machine 310, the temperature in the primary melting crystallizer 110 is checked through the first thermometer 1102, fluoroethylene carbonate in the raw material liquid is cooled and crystallized, after the cooling is finished, pressure is applied to the primary melting crystallizer 110 through the first pressurizing device 4, and the mother liquid which is not crystallized is discharged to the mother liquid storage tank 220, so that the mother liquid can be rapidly separated from crystals under the action of the pressure, the mother liquid and the crystals can be more thoroughly separated, the purity of the crystallized crystals is higher, an included angle alpha between the cross section direction of the heat transfer plate 1101 and the vertical direction is 0-10 degrees, the bearing force of the crystals accumulated on the heat transfer plate on the pressure is improved, the probability that the crystals are discharged along with the mother liquid is reduced, and the flow guide effect on the discharged mother liquid is achieved. The plate tube 130 and the first pressurizing device 4 cooperate to facilitate the discharge of the mother liquid, so that the purification efficiency is higher, and the discharge of the crystals along with the impact of the mother liquid is avoided, thereby avoiding the loss of the crystals. The mother liquor is discharged as wastewater through a mother liquor pump via a raffinate delivery line 620 to a wastewater treatment station.

During cooling crystallization, difluoroethylene carbonate, chloroethylene carbonate and other impurity crystals are carried in fluoroethylene carbonate crystals, so that after mother liquor in the primary melting crystallizer 110 is drained, a heat source is provided for the primary melting crystallizer 110 through the primary cooling and heating integrated machine 310, the impurity crystals in the crystals are heated and melted, and then obtained sweat is discharged to realize heating and sweating. Will send out sweat through first pressure device 4 and transport to raw materials storage tank 210 in for send out sweat and crystal separation more thoroughly, because send out sweat that impurity crystal melting back formed is at the discharge process, and a small amount of fluoroethylene carbonate crystal of inevitable taking out, so, will send out sweat and discharge to raw materials storage tank 210 in, be used for follow-up purification many times, set up like this and not only avoided the waste of fluoroethylene carbonate, still improved the productivity of product fluoroethylene carbonate. After the sweat is exhausted, the primary cooling and heating integrated machine 310 provides a heat source for the primary melting crystallizer 110 again, so that the fluoroethylene carbonate crystals are heated and completely melted to obtain crude fluoroethylene carbonate, and the crude fluoroethylene carbonate crystals are discharged to the crude tank 230 to complete one-time melting crystallization treatment.

Similarly, the crude fluoroethylene carbonate in the crude tank 230 is transported to the secondary melt crystallizer 120 through the crude transport line 610 by the crude pump for the secondary melt crystallization treatment. Provide the cold source to second grade melt crystallizer 120 through second grade cold and hot all-in-one 320, realize the cooling crystallization, after the cooling crystallization, exert pressure in to second grade melt crystallizer 120 through second pressure device 5, in defeated mother liquor to raw materials storage tank 210 for mix the back with the next batch of raw materials liquid in raw materials storage tank 210, purify once more, reduce the waste of fluoroethylene carbonate, be favorable to improving the yield of product fluoroethylene carbonate. After the mother liquor in the secondary melting crystallizer 120 is exhausted, a heat source is provided for the secondary melting crystallizer 120 through the secondary cooling and heating integrated machine 320, the fluoroethylene carbonate crude product is heated and sweated for the second time, so that the impurity crystals are melted, and the obtained sweated liquid is discharged. After the sweat is discharged, the residual crystals in the secondary melting crystallizer 120 are high-purity fluoroethylene carbonate crystals, and the secondary melting crystallizer 120 is heated again through the secondary cooling and heating integrated machine 320, so that the fluoroethylene carbonate crystals are completely melted and discharged to the finished product tank 240, the fluoroethylene carbonate product is obtained, and the purification of fluoroethylene carbonate is completed.

By the scheme, the fluoroethylene carbonate is melted and crystallized, and the purity of the fluoroethylene carbonate can meet the requirement of over 99.9 percent of electronic grade only by twice melting and crystallization, so that the equipment loss is reduced. Through setting up pressure device, can be quick with mother liquor or sweat and crystal separation under the effect of pressure, can make more thorough of mother liquor or sweat and crystal separation moreover, reduce the number of times of melt crystallization, also make the purity of crystal higher. Meanwhile, the plurality of plate pipes and the pressurizing device are used cooperatively, so that the mother liquor is discharged, the purification efficiency is higher, the discharge of crystals along with the impact of the mother liquor is avoided, and the loss of the crystals is avoided. Compared with rectification, the melting crystallization system is lower in energy consumption and simpler in operation, and labor cost and equipment cost are greatly saved.

Fig. 3 is a schematic diagram of a left side structure of the internal baffle plate of the plate tube according to an embodiment of the present invention, and as shown in fig. 3, optionally, a baffle plate 1301 is disposed inside each of the plurality of plate tubes 130, and the baffle plate 1301 has a rectangular or wavy shape.

Specifically, a plurality of heat transfer plates 1101 are arranged in parallel, a plurality of plate tubes 130 are formed by adjacent heat transfer plates 1101, a cooling medium and a heating medium circulate inside the plate tubes 130, a raw material liquid is located outside the plate tubes 130, crystallization, sweating and melting are performed through the cooling medium, and formed crystals grow along the outside of the plate tubes 130. The inside baffling board 1301 that all is provided with of board pipe 130, the setting of baffling board 1301 has changed the direction of motion of cold and hot media, is favorable to cold and hot media to do random motion inside board pipe 130, has improved the heat exchange efficiency of board pipe 130, improves coefficient of heat transfer to can effectively reduce the scale deposit speed in the board pipe 130, also improve fluoroethylene carbonate's purification efficiency simultaneously.

Fig. 4 is a schematic structural diagram of a melt crystallization system for producing fluoroethylene carbonate according to another embodiment of the present invention, as shown in fig. 4, and optionally, the first pressurizing device 4 and the second pressurizing device 5 have the same structure, and the first pressurizing device 4 includes a nitrogen gas delivery pipe 410, a nitrogen gas storage tank 420, a gas pressure regulator 430 and a gas heat exchanger 440.

A gas heat exchanger 440 is connected between the nitrogen gas feed line 410 and the nitrogen gas receiver 420, and a gas pressure regulator 430 is provided between the nitrogen gas receiver 420 and the primary melt crystallizer 110.

Specifically, the nitrogen conveying pipeline 410 is connected to a nitrogen pipe network, and conveys nitrogen into the primary melting crystallizer 110, so that the separation of the mother liquor or sweat from the crystals can be accelerated under the action of pressure. The temperature of the nitrogen gas needs to be the same as the temperature in the primary melt crystallizer 110, if the temperature of the nitrogen gas is too high, the fluoroethylene carbonate crystals are melted and flow out, and if the temperature of the nitrogen gas is too low, sweat is crystallized again, and the purification efficiency of the fluoroethylene carbonate is reduced.

A gas heat exchanger 440 is connected between the nitrogen gas conveying pipeline 410 and the nitrogen gas storage tank 420, and the temperature of the nitrogen gas is reduced or increased through the gas heat exchanger 440 to reach the required temperature. The nitrogen after heat exchange is transmitted to the nitrogen storage tank 420, and the pressure of the nitrogen transmitted into the primary melting crystallizer 110 is controlled by the pressure regulator 430, so as to avoid that the impact on the fluoroethylene carbonate crystals caused by overlarge nitrogen pressure is further output along with the mother liquor or the perspiration liquid, or the pressure is too low to completely separate the crystals from the mother liquor or the perspiration liquid. By means of the arrangement, the temperature and the pressure of the input nitrogen are controlled, and the melting crystallization efficiency is improved.

Optionally, the gas heat exchanger 440 is provided with a hot and cold medium inlet 4401 and a hot and cold medium outlet 4402.

Specifically, the gas heat exchanger 440 is provided with a cold and hot medium inlet 4401 and a cold and hot medium outlet 4402 for introducing cold and hot media to exchange heat with nitrogen, the cold media may be condensed water or an aqueous solution of ethylene glycol, and the hot media may be hot water or water vapor.

Optionally, a second thermometer 4201 is provided on the nitrogen storage tank 420.

Specifically, the second thermometer 4201 is configured to detect the temperature of the nitrogen gas in the nitrogen storage tank 420, and the flow rate of the cooling and heating medium of the gas heat exchanger 440 is adjusted by the indication of the first thermometer 1102 to control the temperature of the nitrogen gas, so that the indication of the second thermometer 4201 is the same as the indication of the first thermometer 1102, which is advantageous for improving the purification efficiency of the melt crystallization system. And compare in purifying fluoro ethylene carbonate through using the rectifier unit, the rectification is different and with fluoro ethylene carbonate and impurity separation through each material boiling point, and the melting crystallization system of this application realizes the purpose of separation and purification through each material melting point is different, though all need set up cooling, heating device, but melting crystalline melting point is compared in the boiling point and is far lower, the heat loss that has significantly reduced, has practiced thrift the energy, and has obviously improved the separation effect.

As shown in fig. 4, the outlet of the mother liquor storage tank 220 is optionally connected to the raw material storage tank 210 via a mother liquor conveying line 630.

Specifically, the mother liquor in the mother liquor storage tank 220 is conveyed to the raw material storage tank 210 through the mother liquor conveying pipeline 630 for purification again, which not only reduces the waste of fluoroethylene carbonate, but also improves the yield of fluoroethylene carbonate. And (3) detecting the mother liquor in the mother liquor storage tank 220, when the content of fluoroethylene carbonate in the mother liquor is more than or equal to 30%, conveying the mother liquor to the raw material storage tank 210 through a mother liquor conveying pipeline 630, and if the content of fluoroethylene carbonate in the mother liquor is less than 30%, conveying the mother liquor to a wastewater treatment station through a residual liquid conveying pipeline 620.

As shown in fig. 4, optionally, the melt crystallization system is further provided with a controller 710.

The controller 710 is respectively connected to the first thermometer 1102, the second thermometer 4201, the air pressure regulator 430, the primary cooling and heating integrated machine 310, and the secondary cooling and heating integrated machine 320.

Specifically, the melt crystallization system is further provided with a controller 710, when the system is operated, the raw material liquid is conveyed into the primary melt crystallizer 110, and the primary melt crystallizer 110 is cooled by the primary cooling and heating all-in-one machine 310, so that the temperature of the first thermometer 1102 reaches a first preset temperature, the fluoroethylene carbonate in the raw material liquid is cooled and crystallized, and the temperature is kept unchanged. The first preset temperature is 17-18 ℃. At the same time, the controller 710 adjusts the flow rate of the cooling medium in the gas heat exchanger 440 to cool the nitrogen gas such that the reading of the second thermometer 4201 reaches the first preset temperature. After crystallization is finished, discharging the non-crystallized mother liquor to a mother liquor storage tank, simultaneously controlling to open the gas pressure regulator 430 to introduce nitrogen with a certain pressure into the primary melting crystallizer 110, controlling the pressure of the nitrogen entering the primary melting crystallizer 110 to reach a preset pressure, wherein the preset pressure is 0-0.3MPa, so that the mother liquor is discharged to the mother liquor storage tank 220, and after the mother liquor is discharged, closing the first pressurizing device 4 by the controller 710.

The primary cooling and heating integrated machine 310 provides a heat source for the primary melt crystallizer 110, so that the temperature of the first thermometer 1102 reaches a second preset temperature, the second preset temperature is 18-20 ℃, the impurity crystals in the crystals are heated and melted to obtain sweat to be discharged, and heating and sweating are realized. Meanwhile, the controller 710 adjusts the flow rate of the heat medium in the gas heat exchanger 440 to increase the temperature of the nitrogen gas such that the readings of the second thermometer 4201 reach a second preset temperature. The temperature in the primary melt crystallizer 110 and the nitrogen temperature are maintained constant. The controller 710 turns on the pressure regulator 430, regulates the pressure of the nitrogen gas entering the primary melt crystallizer 110 to a preset pressure, and discharges the perspiration gas to the raw material storage tank 210, wherein the preset pressure is maintained at 0 to 0.3MPa. Wherein, the cooling crystallization and heating sweating time are both 2-2.5h, the cooling crystallization rate is not too fast, the reduction of the cooling rate slows down the crystal growth rate, is beneficial to the transfer of impurities at the solid-liquid two-phase interface to the liquid phase, and is beneficial to the improvement of the purity of the fluoroethylene carbonate crystal. In the process of heating and sweating, the heating rate is not too fast, so that mass transfer and full separation of solid and liquid are facilitated, and the solid-liquid balance in the crystallizer is achieved.

After the sweat is exhausted, the controller 710 turns off the first pressurizing device 4, and provides a heat source to the primary crystallizer 110 through the primary cooling and heating all-in-one machine 310 again, so that the temperature of the first thermometer 1102 reaches a third preset temperature, and the third preset temperature is 25-30 ℃, so that all the crystals in the primary crystallizer 110 are melted. At the same time, the controller 710 adjusts the flow rate of the heat medium in the gas heat exchanger 440 to increase the temperature of the nitrogen gas again, so that the readings of the second thermometer 4201 reach a third preset temperature. The controller 710 turns on the pressure regulator 430 and regulates the pressure of the nitrogen gas entering the primary melt crystallizer 110 to be 0-0.3MPa. The obtained crude fluoroethylene carbonate is discharged to the crude tank 230, and the first pressurizing device 4 is closed after the crude fluoroethylene carbonate is discharged. The melt crystallization process of the subsequent secondary melt crystallizer 120 is the same as that of the primary melt crystallizer 110.

Optionally, the bottom plates of the primary melting crystallizer 110 and the secondary melting crystallizer 120 are obliquely arranged, and the included angle between the bottom plates and the horizontal direction is 5-10 degrees.

Specifically, the bottom plates of the primary and secondary melters 110, 120 are inclined to facilitate the discharge of mother liquid, perspiration liquid and melt, thereby significantly shortening the purification time.

The technical solution of the present application is illustrated in detail by the following specific examples.

The operation flow of the melt crystallization system for producing fluoroethylene carbonate in the embodiment in specific work is as follows:

first-order melt crystallization process: conveying the raw material liquid in the raw material storage tank 210 into the primary melting crystallizer 110, and cooling the primary melting crystallizer 110 through the primary cooling and heating all-in-one machine 310, so that the temperature of the first thermometer 1102 reaches a first preset temperature, the fluoroethylene carbonate in the raw material liquid is cooled and crystallized, and the temperature is kept unchanged, wherein the first preset temperature is 17-18 ℃. At the same time, the controller 710 adjusts the flow rate of the cooling medium in the gas heat exchanger 440 to cool the nitrogen gas such that the readings of the second thermometer 4201 maintain the first preset temperature. After the crystallization is finished, the first pressurizing device 4 is controlled to be started to introduce nitrogen with a certain pressure into the primary melting crystallizer 110, the pressure of the nitrogen entering the primary melting crystallizer 110 is controlled by adjusting the gas pressure regulator 430 to reach a preset pressure, the preset pressure is 0-0.3MPa, and the mother liquor which is not crystallized is discharged to the mother liquor storage tank 220.

Detecting the mother liquor in the mother liquor storage tank 220, when the content of fluoroethylene carbonate in the mother liquor is more than or equal to 30%, conveying the mother liquor to the raw material storage tank 210 through a mother liquor pump via a mother liquor conveying pipeline 630, and when the content of fluoroethylene carbonate in the mother liquor is less than 30%, conveying the mother liquor to a waste water treatment station via a residual liquid conveying pipeline 620.

After the mother liquor is drained, the controller 710 turns off the first pressurizing means 4. The primary cooling and heating integrated machine 310 provides a heat source for the primary melting crystallizer 110, so that the temperature of the first thermometer 1102 reaches a second preset temperature, the second preset temperature is 18-20 ℃, impurity crystals in the crystals are heated and melted to obtain sweat to be discharged, and heating and sweating are realized. Meanwhile, the controller 710 adjusts the flow rate of the heat medium in the gas heat exchanger 440 to increase the temperature of the nitrogen gas such that the readings of the second thermometer 4201 reach a second preset temperature. The temperature in the primary melt crystallizer 110 and the nitrogen temperature are maintained constant. The controller 710 turns on the pressure regulator 430 to regulate the pressure of the nitrogen gas entering the primary melt crystallizer 110 to a predetermined pressure and to maintain the predetermined pressure, and discharges the perspiration gas to the raw material storage tank 210. The preset pressure is kept between 0 and 0.3MPa.

After the sweat is exhausted, the controller 710 closes the first pressurizing device 4, and provides a heat source for the first-stage melt crystallizer 110 through the first-stage cooling and heating all-in-one machine 310 again, so that the temperature of the first thermometer 1102 reaches a third preset temperature, the third preset temperature is 25-30 ℃, and after all the crystals in the first-stage melt crystallizer 110 are melted, the crude fluoroethylene carbonate is obtained. At the same time, the controller 710 adjusts the flow rate of the thermal medium in the gas heat exchanger 440 to increase the temperature of the nitrogen gas again, so that the readings of the second thermometer 4201 reach and maintain the third preset temperature. The controller 710 turns on the gas pressure regulator 430 and regulates the pressure of the nitrogen gas introduced into the primary melt crystallizer 110 to reach and maintain the preset pressure of 0-0.3MPa. The crude fluoroethylene carbonate is then discharged to crude tank 230. After the crude fluoroethylene carbonate is exhausted, the first pressurizing device 4 is closed. Wherein, the time of cooling crystallization and heating sweating is 2-2.5h.

And (3) secondary melting crystallization process: the crude fluoroethylene carbonate in the crude tank 230 is conveyed to the secondary melt crystallizer 120 through a crude conveying pipeline 610 by a crude pump, and a cold source is provided for the secondary melt crystallizer 120 through a secondary cooling and heating integrated machine 320, so that the temperature of a first thermometer 1102 connected with the secondary melt crystallizer 120 reaches a first preset temperature of 17-18 ℃, the fluoroethylene carbonate in the raw material liquid is cooled and crystallized, and the temperature is kept unchanged. Meanwhile, the controller 710 adjusts the flow rate of the refrigerant in the gas heat exchanger 440, and cools the nitrogen gas so that the reading of the second thermometer 4201 connected to the secondary melt crystallizer 120 reaches the first preset temperature, and after the crystallization is completed, the gas pressure regulator 430 in the second pressurizing device 5 is controlled to be turned on to control the pressure of the nitrogen gas entering the secondary melt crystallizer 120 to reach the preset pressure of 0-0.3MPa, and the mother liquor which is not crystallized is discharged to the raw material storage tank 210.

After the mother liquor is drained, the controller 710 turns off the second pressurizing means 5. The secondary cooling and heating integrated machine 320 provides a heat source for the secondary melting crystallizer 120, so that the temperature of the first thermometer 1102 reaches a second preset temperature of 18-20 ℃, impurity crystals in the crystals are heated and melted to obtain sweat to be discharged, and heating and sweating are realized. At the same time, the controller 710 adjusts the flow rate of the heat medium in the gas heat exchanger 440 to increase the temperature of the nitrogen gas such that the readings of the second thermometer 4201 reach a second preset temperature. The temperature and nitrogen temperature in the secondary melt crystallizer 120 are maintained constant. The controller 710 turns on the pressure regulator 430 in the second pressurizing device 5, regulates the pressure of the nitrogen gas entering the secondary melt crystallizer 120 to reach and maintain the preset pressure, and discharges the perspiration gas to the crude tank 230. Wherein, the time for cooling crystallization and heating sweating in the secondary melt crystallizer 120 is also 2-2.5h.

After the sweat is exhausted, the controller 710 turns off the second pressurizing device 5, and provides a heat source to the secondary crystallizer 120 again through the secondary cooling and heating all-in-one machine 320, so that the temperature of the first thermometer 1102 reaches a third preset temperature of 25-30 ℃, so that all the crystals in the secondary crystallizer 120 are melted, and meanwhile, the controller 710 adjusts the flow rate of the heat medium in the gas heat exchanger 440, and raises the temperature of the nitrogen again, so that the indication number of the second thermometer 4201 reaches the third preset temperature. The controller 710 opens the pressure regulator 430 and regulates the pressure of the nitrogen gas entering the secondary melt crystallizer 120 to reach and maintain the preset pressure, and discharges the obtained fluoroethylene carbonate product to the product tank 240. And after the fluoroethylene carbonate product is exhausted, closing the second pressurizing device 5.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art; the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims (8)

1. A melt crystallization system for producing fluoroethylene carbonate, comprising: the system comprises a primary melt crystallizer (110), a secondary melt crystallizer (120), a raw material storage tank (210), a mother liquor storage tank (220), a crude product tank (230), a finished product tank (240), a primary cooling and heating integrated machine (310), a secondary cooling and heating integrated machine (320), a first pressurizing device (4) and a second pressurizing device (5);

the discharge hole of the primary melt crystallizer (110) is respectively connected with the raw material storage tank (210), the mother liquid storage tank (220) and the crude product tank (230); the primary melting crystallizer (110) is also respectively connected with the primary cooling and heating integrated machine (310) and the first pressurizing device (4);

the discharge hole of the secondary melt crystallizer (120) is respectively connected with the mother liquor storage tank (220), the crude product tank (230) and the finished product tank (240); the secondary melting crystallizer (120) is also respectively connected with the secondary cooling and heating integrated machine (320) and the second pressurizing device (5);

an outlet of the crude product tank (230) is connected with the secondary melt crystallizer (120) through a crude product conveying pipeline (610), and an outlet of the mother liquor storage tank (220) is connected with a residual liquid conveying pipeline (620);

the primary melting crystallizer (110) and the secondary melting crystallizer (120) both adopt static plate type melting crystallizers, the included angle alpha between the cross section direction of a plurality of heat transfer plates (1101) in the static plate type melting crystallizers and the vertical direction is 0-10 degrees, the adjacent heat transfer plates (1101) form a plate pipe (130), and first thermometers (1102) are arranged in the primary melting crystallizer (110) and the secondary melting crystallizer (120).

2. The melt crystallization system for producing fluoroethylene carbonate according to claim 1, wherein a plurality of the plate tubes (130) are each provided with a baffle plate (1301), and the baffle plate (1301) has a rectangular or wavy shape.

3. The melt crystallization system for producing fluoroethylene carbonate according to claim 1, wherein the first pressurizing device (4) and the second pressurizing device (5) have the same structure, and the first pressurizing device (4) comprises a nitrogen gas delivery pipe (410), a nitrogen gas storage tank (420), a gas pressure regulator (430) and a gas heat exchanger (440);

the gas heat exchanger (440) is connected between the nitrogen conveying pipeline (410) and the nitrogen storage tank (420), and the gas pressure regulator (430) is arranged between the nitrogen storage tank (420) and the primary melt crystallizer (110).

4. A melt crystallization system for producing fluoroethylene carbonate according to claim 3, wherein the gas heat exchanger (440) is provided with a hot and cold medium inlet (4401) and a hot and cold medium outlet (4402).

5. The melt crystallization system for producing fluoroethylene carbonate according to claim 4, wherein the nitrogen storage tank (420) is provided with a second thermometer (4201).

6. The melt crystallization system for producing fluoroethylene carbonate according to claim 5, wherein the outlet of the mother liquid storage tank (220) is further connected to the raw material storage tank (210) through a mother liquid transfer line (630).

7. The melt crystallization system for the production of fluoroethylene carbonate according to claim 6, wherein the melt crystallization system is further provided with a controller (710);

the controller (710) is respectively connected with the first thermometer (1102), the second thermometer (4201), the air pressure regulator (430), the primary cold and hot all-in-one machine (310) and the secondary cold and hot all-in-one machine (320).

8. The melt crystallization system for manufacturing fluoroethylene carbonate according to any one of claims 1 to 7, wherein the bottom plates of the primary melt crystallizer (110) and the secondary melt crystallizer (120) are arranged obliquely, and the included angle of the bottom plates with the horizontal direction is 5 to 10 °.

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