CN112516616A - Crystallization device and method for purifying ethylene carbonate - Google Patents
Crystallization device and method for purifying ethylene carbonate Download PDFInfo
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- CN112516616A CN112516616A CN201910889199.0A CN201910889199A CN112516616A CN 112516616 A CN112516616 A CN 112516616A CN 201910889199 A CN201910889199 A CN 201910889199A CN 112516616 A CN112516616 A CN 112516616A
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- 238000002425 crystallisation Methods 0.000 title claims abstract description 125
- 230000008025 crystallization Effects 0.000 title claims abstract description 123
- 238000000034 method Methods 0.000 title claims abstract description 89
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 title claims abstract description 83
- 239000000463 material Substances 0.000 claims abstract description 160
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 129
- 230000035900 sweating Effects 0.000 claims description 95
- 239000013078 crystal Substances 0.000 claims description 64
- 239000002994 raw material Substances 0.000 claims description 50
- 239000012452 mother liquor Substances 0.000 claims description 22
- 210000004243 sweat Anatomy 0.000 claims description 21
- 238000007599 discharging Methods 0.000 claims description 19
- 238000000746 purification Methods 0.000 claims description 19
- 239000003507 refrigerant Substances 0.000 claims description 19
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 3
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 60
- 239000000047 product Substances 0.000 description 34
- 238000000926 separation method Methods 0.000 description 21
- 238000010438 heat treatment Methods 0.000 description 13
- 238000001816 cooling Methods 0.000 description 11
- 239000007795 chemical reaction product Substances 0.000 description 8
- 238000005265 energy consumption Methods 0.000 description 6
- 239000012535 impurity Substances 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- 239000002808 molecular sieve Substances 0.000 description 4
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 238000001179 sorption measurement Methods 0.000 description 3
- 239000003832 thermite Substances 0.000 description 3
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 238000010992 reflux Methods 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000009530 blood pressure measurement Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
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- 238000004043 dyeing Methods 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
- 230000032050 esterification Effects 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
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- 238000001308 synthesis method Methods 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0004—Crystallisation cooling by heat exchange
- B01D9/0013—Crystallisation cooling by heat exchange by indirect heat exchange
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0059—General arrangements of crystallisation plant, e.g. flow sheets
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D9/0063—Control or regulation
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D317/00—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D317/08—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3
- C07D317/10—Heterocyclic 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
- C07D317/32—Heterocyclic 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
- C07D317/34—Oxygen atoms
- C07D317/36—Alkylene carbonates; Substituted alkylene carbonates
- C07D317/38—Ethylene carbonate
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D9/00—Crystallisation
- B01D2009/0086—Processes or apparatus therefor
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- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a crystallization device and a method for purifying ethylene carbonate. The device comprises a shell, wherein a material inlet is formed in the top of the shell, a material outlet is formed in the bottom of the shell, a cold/hot agent inlet and a cold/hot agent outlet are respectively formed in two sides of the shell, and the horizontal position of the cold/hot agent inlet is higher than that of the cold/hot agent outlet; the shell is internally provided with a heat exchange tube and a material distributor, and the material distributor is arranged at the bottom of the shell upper end enclosure; the top of the heat exchange tube is connected with the material distributor, and the bottom of the heat exchange tube is connected with the material outlet through the lower shell end enclosure; and an extension pipe is arranged below the material distributor and is positioned in the heat exchange pipe. The method for purifying the ethylene carbonate by using the device can obtain the ethylene carbonate product with the purity of more than or equal to 99.99 percent.
Description
Technical Field
The invention belongs to the field of purification of ethylene carbonate, and particularly relates to a crystallization device and method for purifying ethylene carbonate.
Background
Ethylene carbonate (EC, C)3H4O3And CAS number: 96-49-1), which is a high boiling point solvent and organic synthesis intermediate with excellent performance, and is widely used in the fields of textile printing and dyeing, polymer synthesis, electrochemistry, medicine and the like, wherein the refined EC is one of the raw materials for producing high-energy lithium ion battery electrolyte and has high added value, so that the refined EC of the power battery grade has a wide development prospect obviously along with the rapid development of the power lithium battery market.
Because the performance of the lithium ion battery depends on the performance and the preparation process of the battery composition materials to a great extent, for example, a small amount of water, alcohol and acid in the electrolyte solvent can cause the reduction of the specific capacity, the conductivity, the cycle efficiency and the like of the lithium ion battery, and even accelerate the deterioration of the electrolyte, in the production process of the power lithium ion battery, strict requirements are made on the purity of the electrolyte solvent, and the EC purity is generally required to reach 99.99%.
At EO and CO2The reaction product of (a) contains a small amount of ethylene glycol, diethylene glycol, water, and unreacted EO, and may contain catalyst residues, etc., in addition to the target product EC. At present, the purification method of battery-grade EC in an industrial device is mainly rectification purification, i.e. EC with purity of more than 90% obtained by crude distillation is further rectified, as described in CN 106588862, however, in the rectification purification process, on one hand, if the temperature in the rectification process is high and the time is long, the polymerization and decomposition of EC are easily caused, and even if there is catalyst residue in the raw material, more decomposition of EC is caused, therefore, in order to ensure the product purity, the temperature in the rectification process needs to be reduced, at this time, a very high vacuum degree (system pressure about 5KPa, absolute pressure) is needed, high requirements are required for both equipment and operation, and the equipment and operation costs are also high; on the other hand, because the purity requirement of the battery-grade EC is very high, the reflux ratio of the rectification process is very high, and the energy consumption is very highHigh. Thus, while purification by distillation is currently the primary method of cell-grade EC production, it is not the most economically desirable method of production and improvements are needed.
By adopting a crystallization separation method, CN101400667B proposes a purification method of feeding an EC solution into a washing tower for countercurrent contact after crystallization, but it is known that a crystal bed layer in the washing tower is not easy to be stable and has high requirements on the operation of equipment.
In addition to conventional rectification and crystallization methods, CN201010598710.0 proposes a molecular sieve adsorption method to dehydrate and remove ethylene glycol from EC material with a purity of about 99.9%, but the molecular sieve is used in a large amount, and adsorbs EC while adsorbing ethylene glycol and water, resulting in EC loss and yield reduction, and at the same time, the molecular sieve is easily saturated by adsorption, resulting in EC material throughput reduction, and further considering molecular sieve regeneration in industrial applications is not an optimal separation method. However, it should be noted that the above processes are all for post-treatment of high purity EC with purity up to 99% or more to further reduce the content of some impurities, such as ethylene glycol and water, but do not consider the prior purification of EC or the design and optimization of the overall process, such as the separation of EC reaction products based on Ethylene Oxide (EO) esterification, and are not suitable for the overall industrial application of EC.
Therefore, compared with the conventional rectification purification method, or other separation methods, or combined separation methods, the direct crystallization separation purification method for the ethylene carbonate, particularly the power battery grade EC is developed, so that the separation energy consumption can be remarkably reduced, the equipment and operation can be greatly simplified, and the direct crystallization separation purification method for the ethylene carbonate, particularly the power battery grade EC can be directly used for industrial production of the power battery grade EC and has obvious advantages.
Disclosure of Invention
The invention provides a crystallization device and a method for purifying ethylene carbonate aiming at the technical problems of high energy consumption, low product purity and the like in the process of separating and purifying ethylene carbonate in the prior art.
To this end, the first aspect of the present invention provides a crystallization apparatus for purifying ethylene carbonate, comprising:
the device comprises a shell, a material inlet is arranged at the top of the shell, a material outlet is arranged at the bottom of the shell, a cold/hot agent inlet and a cold/hot agent outlet are respectively arranged at two sides of the shell, and the horizontal position of the cold/hot agent inlet is higher than that of the cold/hot agent outlet;
the shell is internally provided with a heat exchange tube and a material distributor, and the material distributor is arranged at the bottom of the shell upper end enclosure; the top of the heat exchange tube is connected with the material distributor, and the bottom of the heat exchange tube is connected with the material outlet through the lower shell end enclosure;
and an extension pipe is arranged below the material distributor and is positioned in the heat exchange pipe.
The main structure of the device is a vertical shell-and-tube crystallizer, and the device is also provided with a pressure and temperature measuring port for detecting the temperature and the pressure in the device.
In some embodiments of the invention, the heat exchange tube is of a closed-end structure; preferably, the closing-in structure is an inverted cone closing-in structure or an arc closing-in structure. The shell nosing structure is beneficial to improving the separation effect between the mother liquid and the sweating residual crystals mixed in the crystals in the sweating process, and ensures the sweating effect of the sweating process at higher temperature for longer time, thereby improving the purity of the product.
In other embodiments of the present invention, the number of the heat exchange pipes is two or more. The number of the heat exchange tubes is not definitely limited, and the corresponding number of the heat exchange tubes can be set according to actual needs.
According to the invention, the extension pipe is arranged below the material distributor and is positioned in the heat exchange pipe, so that after entering the device from the material inlet, raw materials containing vinyl carbonate are uniformly distributed through the material distributor, then enter the heat exchange pipe through the extension pipe below the distributor and flow along the inner wall surface of the heat exchange pipe, the heat exchange efficiency of one side of the material is improved, the separation of impurities in the crystallization process is favorably reduced, the bulk density of crystals is increased, and the purity of products is improved. Preferably, the shape of the extension pipe arranged below the material distributor is conical, spiral or zigzag.
In some embodiments of the present invention, the inlet of the cold/hot agent and the exterior of the heat exchange tube are provided with extension tubes, so that the cold/hot agent flows along the outer wall surface of the heat exchange tube after passing through the inlet of the cold/hot agent and the extension tubes disposed outside the heat exchange tube, thereby improving the heat exchange efficiency on one side of the cold/hot agent, not only being beneficial to improving the heat exchange efficiency in the crystallization process and reducing the precipitation of impurities in the crystallization process, but also being beneficial to improving the heat exchange efficiency in the sweating process, and enabling the mother liquor contained in the crystal to be more easily precipitated, thereby improving the product quality. Preferably, the inlet of the cold/hot agent and the extension tube arranged outside the heat exchange tube are in the shape of inverted cone, spiral or zigzag.
In some embodiments of the invention, the apparatus further comprises a nitrogen inlet for introducing nitrogen into the apparatus, the nitrogen inlet being located at the top of the housing.
In some embodiments of the invention, the apparatus further comprises an external material circulation pump, an inlet of the external material circulation pump is connected to the material outlet through a pipeline, and an outlet of the external material circulation pump is connected to the material inlet through a pipeline. The external material circulation pump may be adapted to pump material discharged from the material outlet back to the material inlet.
In other embodiments of the present invention, the apparatus further comprises an external temperature control system containing a cold/hot agent, the outlet of which is connected to the cold/hot agent inlet via a conduit, and the inlet of which is connected to the cold/hot agent outlet via a conduit. The external temperature control system is used to control the temperature of the device.
In a second aspect, the present invention provides a method for purifying ethylene carbonate by crystallization using the apparatus according to the first aspect, comprising the following steps:
s1, introducing the raw material containing the vinyl carbonate into the device through a material inlet of the device, distributing the raw material through a material distributor, and then introducing the raw material into a heat exchange tube along an extension tube below the distributor;
s2, introducing a refrigerant into the device through the inlet of the cold/hot agent of the device, flowing along the outer wall surface of the heat exchange tube through the inlet of the cold/hot agent and an extension tube arranged outside the heat exchange tube, controlling the temperature through an external temperature control system to crystallize the ethylene carbonate in the raw material in the heat exchange tube, and discharging crystallization mother liquor after crystallization is finished;
s3, introducing a hot agent into the device through the cold/hot agent inlet of the device, flowing along the outer wall surface of the heat exchange tube after passing through the cold/hot agent inlet and the extension tube arranged outside the heat exchange tube, controlling the temperature through an external temperature control system, sweating the crystals in the heat exchange tube, discharging sweat from the material outlet of the device, and obtaining the residual crystals in the heat exchange tube as the purified ethylene carbonate product.
In the invention, the refrigerant flows along the outer wall surface of the heat exchange tube, so that the refrigerant directly and efficiently exchanges heat with materials in the tube, and crystals of the ethylene carbonate are gradually crystallized and separated out on the inner wall of the heat exchange tube.
In the invention, the sweat is discharged to the lower end enclosure of the shell through the bottom of the heat exchange tube after seeping out of the crystal layer, and then is discharged through the material outlet positioned at the bottom of the shell.
In some embodiments of the invention, the method further comprises: and after the sweat is discharged, the temperature of the heating agent is continuously raised, the residual crystals in the heat exchange tube are further melted and then flow out from the material outlet, and the obtained purified ethylene carbonate product is collected.
In the method, the ethylene carbonate is separated and purified by adopting a melt crystallization method, and the crystallized crystals and the mother liquor can be directly separated without introducing a third substance, so that the method has the characteristics of simple process steps, high product purity, low energy consumption and the like.
In some embodiments of the invention, the cooling rate in the crystallization process is 0.01-0.15 ℃/min, the crystallization end point temperature is 15-25 ℃, and the constant temperature time at the crystallization end point temperature is not less than 30 min.
In other embodiments of the invention, the temperature rise rate in the sweating process is 0.01-0.1 ℃/min, the sweating end point temperature is 36.5-38 ℃, and the constant temperature time of the sweating end point temperature is not less than 30 min.
In some embodiments of the invention, the formation of crystals during crystallization is natural crystallization or crystallization is initiated by the addition of seed crystals. No seed crystal is added in the natural crystallization process, and the operation is relatively simple. And the crystallization process is initiated, which is beneficial to controlling the supersaturation degree of the crystallization process and improving the purity of the crystal product.
In some preferred embodiments of the present invention, the seed crystal is a magma solution of ethylene carbonate having a solid mass content of not more than 20%; preferably, the adding temperature of the seed crystal is 34-36 ℃.
In some embodiments of the present invention, in order to improve the heat exchange efficiency of the inner wall surface of the tube array, the external material circulation pump is intermittently started after the crystallization process is started, or the external material circulation pump is continuously started, and the raw material containing the vinyl carbonate is kept flowing slowly until the crystallization process is finished. Therefore, the crystallization of the ethylene carbonate can be accelerated, the crystallization rate can be improved, and the mother liquor entrainment in the ethylene carbonate crystallization process can be reduced, so that the yield and the purity of the product can be improved.
In other embodiments of the present invention, the method is performed under nitrogen gas sealing. Because the ethylene carbonate is particularly easy to absorb moisture in the air, the ethylene carbonate can be prevented from contacting the air in the whole purification process including raw material feeding, crystal crystallization and sweating, material storage and the like by adopting a nitrogen sealing mode, the ethylene carbonate is prevented from being decomposed and the purity of the ethylene carbonate is prevented from being reduced due to the introduction of moisture in the air, and the separation and purification effects are further ensured.
In some embodiments of the present invention, the ethylene carbonate content of the ethylene carbonate-containing feedstock is greater than or equal to 90% by mass. The raw material containing the ethylene carbonate can be a direct reaction product or a raw material rich in the ethylene carbonate with the mass content of the ethylene carbonate of which the low-concentration reaction product is primarily purified being more than or equal to 90 percent. Other ethylene carbonate materials with the mass content of more than or equal to 90 percent can also be used. Under the influence of various factors such as a synthesis method, the types of catalysts, different process conditions and the like, the concentration of the ethylene carbonate in the ethylene carbonate reaction product is different, the purity of some ethylene carbonate reaction products is higher than 98%, the purity of some ethylene carbonate reaction products is lower than 90%, and the reaction product with the purity of lower than 90% is subjected to preliminary purification through conventional separation processes such as reduced pressure rectification, single-stage melt crystallization or membrane separation and the like, and then the device and the method are adopted for further separation and purification to obtain a high-purity ethylene carbonate product; meanwhile, compared with a direct rectification separation and purification method which needs high vacuum and high reflux ratio, the method has the advantages of mild separation conditions and obviously reduced energy consumption.
Based on the fact that the fusion latent heat of the ethylene carbonate is obviously lower than the vaporization latent heat of the ethylene carbonate, compared with the traditional rectification and purification method, the method provided by the invention can obviously reduce the energy consumption in the separation process, and meanwhile, the process is milder.
Compared with other crystallization separation processes, the method disclosed by the invention is innovative on the adopted purification device, on one hand, the ethylene carbonate raw material and the cold/heat agent are directly and quickly contacted on the contact surface (namely the inner wall surface and the outer wall surface of the heat exchange tube) by adding the extension tubes at the inner part and the outer part of the heat exchange tube and adding the external circulating pump, so that the heat exchange efficiency in the crystallization and sweating processes is greatly improved, the precipitation of impurities in the crystallization process is favorably reduced, the precipitation of mother liquor mixed in crystals in the sweating process is favorably accelerated, and the purity of EC products is improved. Simultaneously, the bottom design through the heat exchange tube with in the crystallization purification device is the structure of back taper or arc binding off, improved the sweat that perspires in-process from the crystal and the separation effect between the surplus crystal of perspiring, thereby make the process of perspiring of crystal can go on under higher sweating temperature and longer sweating time, impel more crystal layers in attached to or smugglied impurity of smuggleing secretly to appear, both guaranteed going on of perspiring process, the effect of perspiring has been improved again, and then the purity of carbonic ethylene ester product has been improved, better technological effect has been obtained.
The method can obtain the ethylene carbonate product with the purity of more than or equal to 99.99 percent, and the purity can meet the product purity requirements of the general ethylene carbonate industry and other battery grades, particularly the power battery grade ethylene carbonate industry; in addition, the method can be further combined with separation methods such as adsorption, membrane separation and the like so as to further remove impurities such as ethylene glycol, water and the like in the ethylene carbonate crystal product and continuously improve the product quality. Meanwhile, mother liquor and sweat generated in the crystallization and sweating processes can also be continuously subjected to secondary and multistage crystallization and sweating so as to further improve the product yield of the ethylene carbonate.
Drawings
The invention will be further explained with reference to the drawings.
FIG. 1 is a schematic structural diagram of a crystallization apparatus for purifying ethylene carbonate according to the present invention.
FIG. 2 is a schematic view of a portion of an extension tube in accordance with the present invention; wherein (a) and (b) are schematic diagrams of extension tubes below the material distributor (inside the heat exchange tube), and (c) is a schematic diagram of an inlet of the cold/hot agent and the extension tubes outside the heat exchange tube.
Wherein the reference numerals in the figures have the meaning: 1 a crystallization device housing; 2, exchanging a heat pipe; 3, a closing structure at the bottom of the heat exchange tube; 4, a material distributor; 5, an extension pipe below the material distributor; 6 inlet of cold/hot agent, extension tube outside heat exchange tube; 7, a material inlet; 8, a material outlet; 9 a cold/hot agent inlet; 10 cold/hot agent outlet; 11 a nitrogen inlet; 12 a temperature measuring port; 13 a pressure measurement port; 14 external material circulating pump; 15 an external temperature control system; 16 a tapered extension tube; 17 a zigzag extension tube; 18 an inverted conical extension tube.
Detailed Description
In order that the present invention may be more readily understood, the following detailed description will proceed with reference being made to examples, which are intended to be illustrative only and are not intended to limit the scope of the invention. The starting materials or components used in the present invention may be commercially or conventionally prepared unless otherwise specified.
Example 1
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control through an external temperature control system to naturally crystallize the raw material containing EC along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.01 ℃/min, the crystallization end point temperature is 15 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, allowing a hot agent to enter from a cold/hot agent inlet, allowing the hot agent to flow downwards along the outer wall surface of the heat exchange tube, sweating the crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and a material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.994%.
Example 2
With the crystallization apparatus shown in fig. 1, a conical extension tube is arranged below the material distributor, as shown in fig. 2 (a), and an inverted conical extension tube is arranged at the inlet of the cold/hot agent and outside the heat exchange tube, as shown in fig. 2 (c); the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control through an external temperature control system to naturally crystallize the raw material containing EC along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.01 ℃/min, the crystallization end point temperature is 15 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, allowing a hot agent to enter from a cold/hot agent inlet, allowing the hot agent to flow downwards along the outer wall surface of the heat exchange tube, sweating the crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and a material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.994%.
Example 3
Adopting the crystallization device shown in fig. 1, a zigzag extending pipe is arranged below the material distributor, as shown in fig. 2 (b), and an inverted conical extending pipe is arranged at the inlet of the cold/hot agent and outside the heat exchange pipe, as shown in fig. 2 (c); the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control through an external temperature control system to naturally crystallize the raw material containing EC along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.01 ℃/min, the crystallization end point temperature is 15 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, allowing a hot agent to enter from a cold/hot agent inlet, allowing the hot agent to flow downwards along the outer wall surface of the heat exchange tube, sweating the crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and a material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.994%.
Example 4
The crystallization device shown in FIG. 1 is adopted, a spiral extension pipe is arranged below the material distributor, and the spiral extension pipe is arranged at the inlet of the cold/hot agent and outside the heat exchange pipe; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control through an external temperature control system to naturally crystallize the raw material containing EC along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.01 ℃/min, the crystallization end point temperature is 15 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, allowing a hot agent to enter from a cold/hot agent inlet, allowing the hot agent to flow downwards along the outer wall surface of the heat exchange tube, sweating the crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and a material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.994%.
Example 5
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 95.27 percent of ethylene carbonate, 2.93 percent of ethylene glycol and 1.80 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control by an external temperature control system to naturally crystallize the raw material containing EC along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.05 ℃/min, the crystallization end point temperature is 20 ℃, and the constant temperature is kept for 60min at the end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.025 ℃/min, the sweating end point temperature is 36.8 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.996%.
Example 6
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 99.07 percent of ethylene carbonate, 0.56 percent of ethylene glycol and 0.37 percent of other EC by weight percentage are preheated and melted, then enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control by an external temperature control system to naturally crystallize the raw material containing EC along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.10 ℃/min, the crystallization end point temperature is 22.5 ℃, and the constant temperature is kept for 45min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.05 ℃/min, the sweating end point temperature is 37.3 ℃, the constant temperature is kept for 45min at the sweating end point temperature, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.997%.
Example 7
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 99.51 percent of ethylene carbonate, 0.33 percent of ethylene glycol and 0.16 percent of other EC by weight percent are preheated and melted, then enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control by an external temperature control system to naturally crystallize the ethylene carbonate material along the inner wall surface of the heat exchange tube, wherein the temperature reduction rate is 0.15 ℃/min, the crystallization end point temperature is 25 ℃, and the temperature is kept constant at the crystallization end point temperature for 30 min; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.10 ℃/min, the sweating end point temperature is 38 ℃, the constant temperature is kept at the sweating end point temperature for 30min, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.998%.
Example 8
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control through an external temperature control system to enable the raw material containing EC to naturally crystallize along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.05 ℃/min; when the temperature of the material in the heat exchange tube reaches 34 ℃, adding a crystal slurry solution of ethylene carbonate from a material inlet through an external circulating pump, wherein the solid weight content is 20%, crystallizing a raw material containing the ethylene carbonate along the inner wall surface of the heat exchange tube, and controlling the supersaturation degree in the crystallization process; the end point temperature of the crystallization process is 15 ℃, and the constant temperature is kept for 60min at the end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.05 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.995%.
Example 9
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 99.51 percent of ethylene carbonate, 0.33 percent of ethylene glycol and 0.16 percent of other EC by weight percent are preheated and melted, then enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control through an external temperature control system to enable the raw material containing EC to naturally crystallize along the inner wall surface of the heat exchange tube, wherein the cooling rate is 0.15 ℃/min; when the temperature of the material in the heat exchange tube reaches 36 ℃, adding a crystal slurry solution of ethylene carbonate from a material inlet through an external circulating pump, wherein the solid weight content is 15%, crystallizing a raw material containing ethylene carbonate along the inner wall surface of the heat exchange tube, and controlling the supersaturation degree in the crystallization process; the final temperature of the crystallization process is 25 ℃, and the temperature is kept constant for 30min at the final temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.10 ℃/min, the sweating end point temperature is 38 ℃, the constant temperature is kept at the sweating end point temperature for 30min, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.999%.
Example 10
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage enter the end socket from the material inlet after being preheated and melted, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Program temperature control is carried out through an external temperature control system, so that the raw material containing the ethylene carbonate is naturally crystallized along the inner wall surface of the heat exchange tube, and the cooling rate is 0.01 ℃/min; the method comprises the following steps of (1) keeping an external circulating pump on before crystallization of an inner wall surface begins, enabling ethylene carbonate materials to continuously and slowly flow, turning off the external circulating pump after crystals begin to appear, and then turning on the external circulating pump every 120min for 15 min; the crystallization end point temperature is 15 ℃, and the constant temperature is kept for 40min at the end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.996%.
Example 11
The crystallization device shown in figure 1 is adopted, a conical extension tube with a straight flow tube is arranged below a material distributor, and a saw-tooth extension tube is arranged at the inlet of a cold/hot agent and outside a heat exchange tube; the bottom of the heat exchange tube is closed in an inverted cone shape.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet, enter the interior of the heat exchange tube through the material distributor and the extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Program temperature control is carried out through an external temperature control system, so that the raw material containing the ethylene carbonate is naturally crystallized along the inner wall surface of the heat exchange tube, and the cooling rate is 0.01 ℃/min; keeping an external circulating pump on in the crystallization process, and enabling the ethylene carbonate material to continuously and slowly flow, wherein the crystallization end point temperature is 15 ℃ and the constant temperature is kept for 40min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.997%.
Example 12
The crystallization device shown in figure 1 is adopted, the lower part of the material distributor is provided with a conical extension tube with a straight flow tube, and the inlet of the cold/hot agent and the outer part of the heat exchange tube are provided with sawtooth extension tubes; the bottom of the heat exchange tube is arc-shaped and closed.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter an upper end socket of a feeder from a material inlet, enter the interior of the heat exchange tube through a material distributor and an extension tube below the material distributor, and flow downwards along the inner wall surface of the heat exchange tube. The refrigerant enters from the cold/hot agent inlet, passes through the cold/hot agent inlet and the extension tube outside the heat exchange tube and then flows downwards along the outer wall surface of the heat exchange tube.
Carrying out program temperature control through an external temperature control system to naturally crystallize the raw material containing the ethylene carbonate along the inner wall surface of the heat exchange tube, wherein the temperature reduction rate is 0.01 ℃/min, the crystallization end point temperature is 15 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, allowing a hot agent to enter from a cold/hot agent inlet, allowing the hot agent to flow downwards along the outer wall surface of the heat exchange tube, sweating the crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and a material outlet simultaneously in the sweating process; and after sweating is stopped, the temperature of the heating agent is continuously increased, residual crystals in the heat exchange tube are melted and collected, and the purity of the final EC product is 99.994%.
Comparative example 1
The same raw material composition and process scheme as in example 1 were adopted, but the heat exchange tubes in the apparatus were straight tubes of uniform inside diameter and without bottom necking, and no extension tubes were provided below the material distributor, at the inlet of the cold/hot agent and outside the heat exchange tubes.
Raw materials which comprise 90.15 percent of ethylene carbonate, 6.23 percent of ethylene glycol and 3.62 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet and enter the heat exchange tube through the material distributor. The refrigerant enters from the cold/hot agent inlet.
Carrying out program temperature control by an external temperature control system to naturally crystallize the ethylene carbonate material along the inner wall surface of the heat exchange tube, wherein the temperature reduction rate is 0.01 ℃/min, the crystallization end point temperature is 15 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.01 ℃/min, the sweating end point temperature is 36.5 ℃, the constant temperature is kept for 40min at the sweating end point temperature, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; after sweating was stopped, the temperature of the thermite was increased continuously, and the residual crystals in the heat exchanger tube were melted and collected, resulting in an EC product purity of 99.913%.
Comparative example 2
The same raw material composition and process scheme as in example 5 were used, but the heat exchange tubes in the apparatus were straight tubes of uniform inside diameter and without bottom necking, and no extension tubes were provided below the material distributor, at the inlet of the cold/hot agent and outside the heat exchange tubes.
Raw materials which comprise 95.27 percent of ethylene carbonate, 2.93 percent of ethylene glycol and 1.80 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet and enter the heat exchange tube through the material distributor. The refrigerant enters from the cold/hot agent inlet.
Carrying out program temperature control through an external temperature control system to naturally crystallize the raw material containing the ethylene carbonate along the inner wall surface of the heat exchange tube, wherein the temperature reduction rate is 0.05 ℃/min, the crystallization end point temperature is 20 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.025 ℃/min, the sweating end point temperature is 36.8 ℃, the constant temperature is kept at the sweating end point temperature for 30min, and the sweat is discharged through a lower end enclosure and the material outlet simultaneously in the sweating process; after sweating was stopped, the temperature of the thermite was increased continuously, and the residual crystals in the heat exchanger tube were melted and collected, resulting in an EC product purity of 99.926%.
Comparative example 3
The same raw material composition and process conditions as those of example 5 were adopted, but the heat exchange tubes in the apparatus were straight tubes of uniform inside diameter and without bottom necking, and no extension tubes were provided below the material distributor, at the inlet of the cold/hot agent and outside the heat exchange tubes.
Raw materials which comprise 95.27 percent of ethylene carbonate, 2.93 percent of ethylene glycol and 1.80 percent of other EC by weight percentage are preheated and melted, enter the upper end enclosure from the material inlet and enter the heat exchange tube through the material distributor. The refrigerant enters from the cold/hot agent inlet.
Carrying out program temperature control through an external temperature control system to naturally crystallize the raw material containing the ethylene carbonate along the inner wall surface of the heat exchange tube, wherein the temperature reduction rate is 0.05 ℃/min, the crystallization end point temperature is 20 ℃, and the constant temperature is kept for 60min at the crystallization end point temperature; after crystallization is stopped, discharging crystallization mother liquor from a material outlet, raising the temperature through an external temperature control system, introducing a hot agent from a cold/hot agent inlet, sweating crystals attached to the inner wall surface of the heat exchange tube, wherein the temperature raising rate is 0.025 ℃/min, the sweating end point temperature is 36.3 ℃, the constant temperature is kept at the sweating end point temperature for 60min, and the sweat is discharged through a lower end enclosure and a material outlet simultaneously in the sweating process; after sweating was stopped, the temperature of the thermite was increased continuously, and the residual crystals in the heat exchanger tube were melted and collected, resulting in an EC product purity of 99.908%.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. A crystallization apparatus for purifying ethylene carbonate, comprising:
the device comprises a shell, a material inlet is arranged at the top of the shell, a material outlet is arranged at the bottom of the shell, a cold/hot agent inlet and a cold/hot agent outlet are respectively arranged at two sides of the shell, and the horizontal position of the cold/hot agent inlet is higher than that of the cold/hot agent outlet;
the shell is internally provided with a heat exchange tube and a material distributor, and the material distributor is arranged at the bottom of the shell upper end enclosure; the top of the heat exchange tube is connected with the material distributor, and the bottom of the heat exchange tube is connected with the material outlet through the lower shell end enclosure;
and an extension pipe is arranged below the material distributor and is positioned in the heat exchange pipe.
2. The apparatus of claim 1, wherein the bottom of the heat exchange tube is of a closed structure; preferably, the closing-in structure is an inverted cone-shaped closing-in structure or an arc-shaped closing-in structure; and/or the number of the heat exchange tubes is two or more.
3. The apparatus of claim 1 or 2, wherein the extension tube disposed below the material distributor is in the shape of a cone, a spiral, or a zigzag.
4. The apparatus according to any one of claims 1 to 3, wherein the inlet of the cold/hot agent and the outside of the heat exchange tube are provided with extension tubes; preferably, the shape of the extension tube provided at the inlet of the cold/hot agent and outside the heat exchange tube is reverse taper, spiral or zigzag.
5. The apparatus of any one of claims 1-4, further comprising a nitrogen inlet located at the top of the housing.
6. The apparatus according to any one of claims 1 to 5, further comprising an external material circulation pump, an inlet of the external material circulation pump being connected to the material outlet via a pipeline, an outlet of the external material circulation pump being connected to the material inlet via a pipeline; and/or the device further comprises an external temperature control system, wherein an outlet of the external temperature control system is connected with the cold/hot agent inlet through a pipeline, and an inlet of the external temperature control system is connected with the cold/hot agent outlet through a pipeline.
7. A method for the crystallization purification of ethylene carbonate by using the apparatus according to any one of claims 1 to 6, comprising the steps of:
s1, introducing the raw material containing the vinyl carbonate into the device through a material inlet of the device, distributing the raw material through a material distributor, and then introducing the raw material into a heat exchange tube along an extension tube below the material distributor;
s2, introducing a refrigerant into the device through the inlet of the cold/hot agent of the device, flowing along the outer wall surface of the heat exchange tube through the inlet of the cold/hot agent and an extension tube arranged outside the heat exchange tube, controlling the temperature through an external temperature control system to crystallize the ethylene carbonate in the raw material in the heat exchange tube, and discharging crystallization mother liquor after crystallization is finished;
s3, introducing a hot agent into the device through the cold/hot agent inlet of the device, flowing along the outer wall surface of the heat exchange tube after passing through the cold/hot agent inlet and the extension tube arranged outside the heat exchange tube, controlling the temperature through an external temperature control system, sweating the crystals in the heat exchange tube, discharging sweat from the material outlet of the device, and obtaining the residual crystals in the heat exchange tube as the purified ethylene carbonate product.
8. The method according to claim 7, wherein the temperature reduction rate in the crystallization process is 0.01-0.15 ℃/min, the crystallization end point temperature is 15-25 ℃, and the constant temperature time at the crystallization end point temperature is not less than 30 min; and/or
The temperature rise rate in the sweating process is 0.01-0.1 ℃/min, the sweating end point temperature is 36.5-38 ℃, and the constant temperature time of the sweating end point temperature is not less than 30 min.
9. The method according to claim 7 or 8, wherein the formation of crystals during crystallization is natural crystallization or crystallization is initiated by adding seed crystals; preferably, the seed crystal is a crystal slurry solution of ethylene carbonate with the solid weight content not higher than 20%; further preferably, the adding temperature of the seed crystal is 34-36 ℃; still further preferably, the external material circulation pump is intermittently turned on or continuously turned on during the crystallization.
10. The method according to any one of claims 7 to 9, wherein the method is carried out under nitrogen gas sealing; and/or the weight content of the ethylene carbonate in the raw material containing the ethylene carbonate is more than or equal to 90 percent.
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| CN113979987A (en) * | 2021-12-27 | 2022-01-28 | 山东海科新源材料科技股份有限公司 | Purification device and method for high-purity ethylene carbonate |
| CN115487530A (en) * | 2022-09-22 | 2022-12-20 | 天津科技大学 | Ethylene carbonate melt crystallization system and process |
| CN116836730A (en) * | 2022-03-23 | 2023-10-03 | 中国石油化工股份有限公司 | Device and method for producing phase-change wax |
| US11958820B2 (en) * | 2021-10-18 | 2024-04-16 | Shenzhen Capchem Technology Co., Ltd. | Method for purifying ethylene carbonate through dynamic crystallization |
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