Purification system for electronic-grade ethylene carbonate and method for preparing ethylene carbonate

Abstract

The present application relates to the technical field of ethylene carbonate production, in particular to a purification system for electronic-grade ethylene carbonate and a preparation method of ethylene carbonate; comprising an evaporation unit, a heat conduction unit and a melt crystallization unit; the evaporation unit comprises a wiped film evaporator; the melt crystallization unit comprises a melt crystallizer; the heat conduction unit comprises a heat exchange unit and a refrigeration unit; the heat exchange unit is connected with the melt crystallization unit through the refrigeration unit or / and directly; the disclosed purification system and preparation method can fully utilize the heat conduction water unit to recover and utilize the heat of ethylene carbonate crude product, then use the heat water unit to exchange heat with the heat conduction water, part of the heat water is used as the heat source of melt crystallization, and the other part of the heat water is used as the heat source of a heat water type lithium bromide refrigerator to prepare low-temperature water as the cold source of melt crystallization, without additional steam consumption, which greatly reduces the energy consumption.

Description

Technical Field

[0001] This invention relates to the field of ethylene carbonate production technology, specifically to a purification system for electronic-grade ethylene carbonate and a method for preparing ethylene carbonate. Background Technology

[0002] Ethylene carbonate is a heterocyclic ketone, also known as 1,3-dioxolane, ethylene glycol carbonate, etc.

[0003] Ethylene carbonate is a high-performance solvent and fine chemical intermediate. It is a potential basic raw material for organic chemicals and can be used as a solvent in textiles, printing and dyeing, polymer synthesis and electrochemistry.

[0004] Ethylene carbonate is an important raw material for lithium battery electrolytes. With the development of the lithium battery industry, the purity requirements of ethylene carbonate in lithium battery electrolytes are getting higher and higher, generally requiring a purity (mass percentage, the same below) ≥99.99%.

[0005] Typically, the purity of crude ethylene carbonate after catalyst removal via a scraped-film evaporator can only reach 99.0%, not 99.9%, barely meeting the acceptable industrial grade and failing to meet the requirements for lithium battery electrolytes.

[0006] To purify crude ethylene carbonate, multi-stage distillation is typically used industrially to remove light components first, then heavy components, and finally electronic-grade ethylene carbonate.

[0007] Distillation purification is an energy-intensive purification process. One ton of electronic-grade ethylene carbonate typically requires 2.0 to 3.5 tons of steam, resulting in high production costs and affecting the economic efficiency of the plant operation.

[0008] For example, the content disclosed in patent 202110294426.2 - "An apparatus and method for producing electronic grade ethylene carbonate".

[0009] Therefore, in order to improve or solve at least one of the above problems, it is necessary to optimize the design of the purification equipment or process of ethylene carbonate. Summary of the Invention

[0010] The purpose of this invention is to provide a purification system capable of producing electronic-grade ethylene carbonate.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] A purification system for electronic-grade ethylene carbonate includes an evaporation unit, a heat conduction unit, and a melt crystallization unit;

[0013] The evaporation unit is connected to the melting and crystallization unit through a heat-conducting unit;

[0014] The evaporation unit includes a scraped film evaporator;

[0015] The melt crystallization unit includes a melt crystallizer;

[0016] The heat-conducting unit includes a heat exchange unit and a refrigeration unit;

[0017] The heat exchange unit is connected to the melting and crystallization unit via a refrigeration unit and / or directly.

[0018] The heat exchange unit includes a hot water transfer unit and a hot water unit;

[0019] The heat-conducting unit is connected to the hot water unit;

[0020] The evaporation unit is connected to the melting and crystallization unit through a hot water conduction unit and a hot water unit;

[0021] The hot water transfer unit includes a hot water heat exchanger; the hot water unit includes a hot water heat exchanger;

[0022] The hot water heat exchanger is connected to the hot water heat exchanger through the first pipe mechanism 15;

[0023] The hot water heat exchanger is connected to the melting and crystallization unit via a second piping mechanism.

[0024] The first pipeline structure 15 includes a first inlet pipe and a first return pipe, and the hot water heat exchanger is connected to the hot water heat exchanger through the first inlet pipe and the first return pipe respectively;

[0025] A hot water transfer pump is installed on the first water inlet pipe.

[0026] The second pipeline structure includes a primary water supply pipeline and a secondary water supply pipeline, wherein the primary water supply pipeline is connected to the melting crystallizer via a refrigeration unit;

[0027] The secondary water supply pipeline is connected to the melting crystallizer.

[0028] The purification system further includes a hot water storage unit; the hot water storage unit includes a hot water storage tank; a third pipeline mechanism is connected to the hot water storage tank; and a hot water delivery pump is installed on the third pipeline mechanism.

[0029] The hot water storage tank is connected to the refrigeration unit and the melting and crystallization unit through a third pipeline mechanism.

[0030] The purification system also includes a low-temperature water storage unit; the low-temperature water storage unit includes a low-temperature water storage tank, which is connected to a fourth pipeline mechanism; a low-temperature water delivery pump is provided on the fourth pipeline mechanism;

[0031] The low-temperature water storage tank is connected to the refrigeration unit and the melting and crystallization unit through a fourth pipeline mechanism.

[0032] The purification system also includes a material supply unit; the material supply unit includes a crude ethylene carbonate product storage tank; the crude ethylene carbonate product storage tank is connected to the melting and crystallization unit via a crude ethylene carbonate product transfer pump.

[0033] A method for preparing electronic-grade ethylene carbonate, wherein the preparation method requires the use of the purification system;

[0034] The preparation method includes the following steps:

[0035] Step 1: The ethylene carbonate reactants are subjected to vacuum distillation in a scraped film evaporator to remove the catalyst and obtain crude ethylene carbonate product;

[0036] Step 2: The crude ethylene carbonate product is repeatedly crystallized, evaporated, and melted in a melt crystallizer to obtain electronic grade ethylene carbonate.

[0037] The crude ethylene carbonate product generated in step 1 is initially cooled by a hot water transfer unit; the hot water transfer unit exchanges heat with the crude ethylene carbonate product from step 1; then the heat is transferred to the hot water unit; the hot water unit then transfers the heat to the refrigeration unit and the melting crystallizer.

[0038] The advantages of this invention are:

[0039] This invention discloses a purification system for electronic-grade ethylene carbonate and a method for preparing ethylene carbonate.

[0040] The purification system and preparation method disclosed in this invention can fully utilize the heat from the crude ethylene carbonate product recovered by the hot water transfer unit, and then use the hot water unit to exchange heat with the hot water. Part of the hot water is used as the heat source for melting and crystallization, and the other part of the hot water is used as the heat source for a hot water-type lithium bromide refrigerator to prepare low-temperature water as the cold source for melting and crystallization. No additional steam consumption is required, which greatly reduces energy consumption.

[0041] Meanwhile, since the material does not require high-temperature distillation, the problem of increased impurities affecting product purity due to side reactions during high-temperature distillation is avoided. Therefore, the yield of electronic-grade ethylene carbonate produced by the purification system disclosed in this invention is much higher than that of the distillation process. Attached Figure Description

[0042] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0043] Figure 1 This is a schematic diagram of the structure of the present invention.

[0044] The markings in the above figures are all:

[0045] 1. Catalyst transfer pump; 2. Scraped film evaporator; 3. Hot water heat exchanger; 4. Hot water transfer pump; 5. Hot water expansion tank; 6. Hot water heat exchanger; 7. Hot water transfer pump; 8. Hot water storage tank; 9. Hot water type lithium bromide refrigerator; 10. Low temperature water transfer pump; 11. Melting crystallization system; 12. Low temperature water storage tank; 13. Ethylene carbonate crude product transfer pump; 14. Ethylene carbonate crude product storage tank. Detailed Implementation

[0046] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0047] A purification system for electronic-grade ethylene carbonate includes an evaporation unit, a heat conduction unit, and a melting crystallization unit. This invention discloses a purification system where, through the use of the heat conduction unit, the heat from the crude ethylene carbonate product can be reused. In practical use, part of this heat can be used as a heat source for melting crystallization (partially hot water), and the other part can be used as a heat source for a hot water-type lithium bromide refrigerator 9 to prepare low-temperature water for melting crystallization. Therefore, the purification system disclosed in this invention does not require additional steam consumption, greatly reducing the energy consumption of the purification system.

[0048] Specifically, the purification system disclosed in this invention changes the traditional purification method of ethylene carbonate. By using an evaporation unit and a melt crystallization unit in combination, this invention avoids the problem of increased impurities affecting product purity due to side reactions during high-temperature distillation, since the material does not require high-temperature distillation. Therefore, the yield of electronic-grade ethylene carbonate produced by the purification system disclosed in this invention is much higher than that of the distillation process.

[0049] In addition, the use of the heat-conducting unit in this invention allows for the heat exchange and absorption of the crude ethylene carbonate product and steam for subsequent use. That is, the heat absorbed by the heat-conducting unit can be transferred to the subsequent units of the purification system for use in other units. This not only reduces the loss of steam heat in the evaporation unit, but also avoids the problem of needing additional supply when subsequent melting and crystallization units or other units require a heat source or cold source.

[0050] Furthermore, in this invention, the evaporation unit is connected to the melting and crystallization unit via a heat-conducting unit; through the bridging of the heat-conducting unit, the heat overflowing from the evaporation unit is utilized in the melting and crystallization unit; the heat overflowing from the evaporation unit is utilized more effectively; and the energy loss of the purification system is reduced.

[0051] The evaporation unit described in this invention includes a scraped film evaporator 2; the scraped film evaporator 2 is mainly used for vacuum distillation of ethylene carbonate reactants to remove the catalyst and obtain crude ethylene carbonate product.

[0052] In this invention, the melt crystallization unit includes a melt crystallizer 11; the melt crystallizer 11 repeatedly crystallizes, sweats, and melts the crude ethylene carbonate product to obtain electronic grade ethylene carbonate.

[0053] Meanwhile, the heat-conducting unit in this invention includes a heat exchange unit and a refrigeration unit. The heat exchange unit facilitates the cooling of the crude ethylene carbonate product produced by the scraped film evaporator 2. While cooling, it also absorbs heat from the crude ethylene carbonate product. The absorbed heat can be transferred to the subsequent refrigeration unit or melting crystallization unit. In subsequent actual production, the refrigeration unit or melting crystallization unit does not require additional steam consumption, which greatly reduces energy consumption.

[0054] In addition, the heat exchange unit described in this invention is connected to the melting and crystallization unit via the refrigeration unit and / or directly; here, the heat exchange unit adopts the above-mentioned connection method. In actual use, part of the heat absorbed by the heat exchange unit can be used as a heat source for melting and crystallization, and the other part of the heat can be used as a heat source for the hot water type lithium bromide refrigerator 9 to prepare low-temperature water as a cold source for melting and crystallization; the refrigeration unit or the melting and crystallization unit can be used without additional steam consumption, which greatly reduces energy consumption.

[0055] Furthermore, the heat exchange unit described in this invention includes a hot water conduction unit and a hot water unit; by using the hot water conduction unit and the hot water unit in combination, this invention can achieve two cooling processes for the heat in the crude vinyl ester product, avoiding the problem of excessive heat entering the subsequent refrigeration unit or melting crystallization unit.

[0056] In actual connection, the heat-conducting unit described in this invention is connected to the hot water unit; this connection method can realize that the heat unit and the hot water unit are arranged in series. This setting can realize that the heat exchange unit degrades the heat in the crude vinyl ester product twice, and better avoids excessive heat being supplied to the subsequent units.

[0057] Meanwhile, in this invention, the evaporation unit is connected to the melting and crystallization unit via a hot water transfer unit and a hot water unit; the hot water transfer unit includes a hot water heat exchanger 3; the hot water unit includes a hot water heat exchanger 6; in this invention, the hot water heat exchanger 3 enables the crude vinyl ester product and steam to undergo a primary heat exchange with the hot water in the hot water heat exchanger 3, while the hot water heat exchanger 6 also has flowing water, and subsequently the hot water undergoes a secondary heat exchange with the flowing water in the heat exchanger, thereby realizing the transfer of heat from the crude vinyl ester product to the subsequent processes.

[0058] In addition, in this invention, the hot water heat exchanger 3 is connected to the hot water heat exchanger 6 through the first pipe mechanism 15; the first pipe mechanism 15 facilitates the connection and communication between the hot water heat exchanger 3 and the hot water heat exchanger 6, and facilitates the flow of hot water between the hot water heat exchanger 3 and the hot water heat exchanger 6.

[0059] In this invention, the hot water heat exchanger 6 is connected to the melting and crystallization unit through the second pipe mechanism 16; the second pipe mechanism 16 facilitates the connection and communication between the hot water heat exchanger 6 and the melting and crystallization unit.

[0060] In practice, the second pipeline mechanism 16 is mainly connected to the melting and crystallization unit through the third pipeline mechanism 17; this arrangement facilitates the connection and communication between the subsequent hot water storage unit, the melting and crystallization unit, and the hot water heat exchanger 6.

[0061] In this invention, the first pipeline mechanism 15 includes a first inlet pipe 151 and a first return pipe 152. The hot water heat exchanger 6 is connected to the hot water heat exchanger 3 through the first inlet pipe 151 and the first return pipe 152. In actual arrangement, the first inlet pipe 151 is connected to the outlet of the hot water heat exchanger 6, and the other end of the first inlet pipe 151 is connected to the hot water inlet. The first return pipe 152 is connected to the hot water outlet, and the other end of the first return pipe 152 is connected to the inlet of the hot water heat exchanger 6. Based on this arrangement, the first pipeline mechanism 15, the hot water heat exchanger 3, and the hot water heat exchanger 6 form a closed loop. Under the action of the subsequent hot water transfer pump 4, the circulation of hot water is realized.

[0062] In addition, in this invention, a hot water transfer pump 4 is provided on the first water inlet pipe 151; the hot water transfer pump 4 in this invention can realize the reciprocating flow of hot water in the hot water heat exchanger 3 and the hot water heat exchanger 6 to achieve heat exchange; at the same time, in order to ensure the safety of the entire system operation, in this invention, a hot water expansion tank 5 is required to be connected to the first water inlet pipe 151.

[0063] Meanwhile, in this invention, the second pipeline mechanism 16 includes a primary water supply pipeline 161 and a secondary water supply pipeline 162. The primary water supply pipeline 161 is connected to the melting crystallizer 11 through the refrigeration unit; the secondary water supply pipeline 162 is connected to the melting crystallizer 11. In this invention, the primary water supply pipeline 161 is used for the connection between the refrigeration unit and the hot water heat exchanger 6, which allows the hot water heat exchanger 6 to provide hot water to the refrigeration unit, enabling the refrigeration unit to produce low-temperature water; and facilitating the subsequent supply of a cold source to the melting crystallizer 11.

[0064] In this invention, the refrigeration unit includes a hot water type lithium bromide refrigerator 9.

[0065] The secondary water supply pipe 162 serves two purposes: firstly, it connects to the hot water storage unit, and secondly, it connects to the melting crystallizer 11. This facilitates control of the hot water flow in the hot water heat exchanger 6, making it convenient for subsequent use.

[0066] In actual use, the installation of the secondary water supply pipe 162 also facilitates the entry of water from the hot water storage unit into the hot water heat exchanger, enabling the water to enter the hot water heat exchanger 6 for subsequent recycling.

[0067] Meanwhile, when supplying heat to the melting crystallizer 11, it is generally done through a hot water storage unit. Of course, it is also feasible to supply heat directly to the melting crystallizer 11 through the hot water heat exchanger 6 and the first heating pipe 171. For example, an external pipe is added to the outlet end of the hot water heat exchanger and connected to the first heating pipe 171 to supply the required heat to the melting crystallizer 11. The specific choice is made according to the needs. At the same time, in order to better control the supply temperature, supplying heat to the melting crystallizer 11 through the hot water storage unit has a better effect.

[0068] Meanwhile, in practical use, the heat exchange unit is connected to the melting and crystallization unit through the refrigeration unit and / or directly; this means that there are multiple connection relationships between the heat exchange unit and the melting and crystallization unit. When the heat exchange unit is connected to the melting and crystallization unit through the refrigeration unit, low-temperature water can be produced using the refrigeration unit, while the heat exchange unit supplies the heat source required by the refrigeration unit. Alternatively, when the heat exchange unit is connected directly to the melting and crystallization unit, it can directly provide the working heat source for the melting and crystallization unit. Based on the above design, it can be seen that the heat exchange unit of this invention will have different usage effects depending on the arrangement of the connecting pipes; the appropriate method should be selected according to actual requirements during actual implementation.

[0069] Furthermore, the purification system in this invention also includes a hot water storage unit; the hot water storage unit includes a hot water storage tank 8; a third pipeline mechanism 17 is connected to the hot water storage tank 8; a hot water delivery pump 7 is provided on the third pipeline mechanism 17; the use of the hot water storage unit can realize the storage of hot water in the heat exchange unit, and at the same time facilitate the subsequent use of other units that require a heat source for heating operations; in this invention, the hot water storage tank 8 is connected to the refrigeration unit and the melting crystallization unit through the third pipeline mechanism 17; the third pipeline mechanism 17 includes a first heating pipeline 171, a second... The heating pipe 172 and the third heating pipe 173 are provided. The first heating pipe 171 is used to connect and communicate with the hot water storage tank 8 and the melting crystallization unit. A hot water delivery pump 7 is also provided on the first heating pipe 171 to facilitate the pumping of hot water from the hot water storage tank 8. The second heating pipe 172 is mainly used to connect and communicate with the refrigeration unit and the hot water storage tank 8, so that the hot water discharged from the refrigeration unit can enter the hot water storage tank. The third heating pipe 173 is mainly used to connect and communicate with the melting crystallization unit and the hot water storage tank 8, so that the hot water discharged from the melting crystallization unit can be stored.

[0070] Meanwhile, as a further optimization, in this invention, the first heating pipe 171 is connected to the secondary water supply pipe 162 in the second pipe structure 16. Based on this design, it is convenient to connect and communicate between the hot water heat exchanger 6 and the hot water storage tank 8 and the melting crystallization unit.

[0071] Furthermore, the purification system described in this invention also includes a low-temperature water storage unit; the low-temperature water storage unit includes a low-temperature water storage tank 12, which is connected to a fourth pipeline mechanism 18; the fourth pipeline mechanism 18 is equipped with a low-temperature water delivery pump 10; the use of the low-temperature water storage unit in this invention can realize the storage of low-temperature water in the heat exchange unit, and at the same time facilitate the supply of low-temperature water to other units that require a cold source in subsequent use.

[0072] In this invention, the low-temperature water storage tank 12 is connected to the refrigeration unit and the melting and crystallization unit via a fourth piping mechanism 18. The fourth piping mechanism 18 includes a first cooling pipe 181 and a second cooling pipe 182. In this invention, the second cooling pipe 182 is used for connection and communication between the low-temperature water storage tank 12 and the melting and crystallization unit. The first heating pipe 171 is mainly used for connection and communication between the refrigeration unit and the low-temperature water storage tank 12. At the same time, a low-temperature water delivery pump 10 is provided on the first cooling pipe 181 to facilitate pumping low-temperature water from the low-temperature water storage tank 12. The low-temperature water storage tank 12 is connected to the refrigeration unit and the melting and crystallization unit via the fourth piping mechanism 18. Based on this design, it is convenient for the low-temperature water storage tank 12 to supply low-temperature water to units that require a cold source.

[0073] Furthermore, the purification system described in this invention also includes a material supply unit; the material supply unit includes a crude ethylene carbonate product storage tank 14; the crude ethylene carbonate product storage tank 14 is connected to the melting and crystallization unit via a crude ethylene carbonate product transfer pump 13; based on this design, the crude ethylene carbonate product storage tank 14 facilitates the storage of crude ethylene carbonate product, while the crude ethylene carbonate product transfer pump 13 facilitates the continuous supply of materials to the melting and crystallization unit.

[0074] A method for preparing electronic-grade ethylene carbonate, wherein the preparation method requires the use of the purification system;

[0075] The preparation method includes the following steps:

[0076] Step 1: The ethylene carbonate reactants are subjected to vacuum distillation in a scraped film evaporator 2 to remove the catalyst and obtain crude ethylene carbonate product;

[0077] Step 2: The crude ethylene carbonate product is repeatedly crystallized, evaporated, and melted in the melt crystallizer 11 to obtain electronic grade ethylene carbonate.

[0078] Based on the above design, the production of electronic-grade ethylene carbonate can be easily realized.

[0079] In addition, in this invention, the crude ethylene carbonate product generated in step 1 is initially cooled by a hot water transfer unit; the hot water transfer unit exchanges heat with the crude ethylene carbonate product in step 1; then the heat is transferred to the hot water unit; the hot water unit then transfers the heat to the refrigeration unit and the melting crystallizer 11; based on the above design and operation, the heat of the crude ethylene carbonate product can be fully utilized by the hot water transfer unit, and then the hot water unit is used to exchange heat with the hot water. Part of the hot water is used as the heat source for melting crystallization, and the other part of the hot water is used as the heat source for the hot water type lithium bromide refrigerator 9 to prepare low-temperature water as the cold source for melting crystallization. No additional steam consumption is required, which greatly reduces energy consumption.

[0080] Specifically, in this invention, a hot water transfer unit is used to cool the crude ethylene carbonate product of step 1. The heated hot water then transfers heat to the hot water unit through a heat exchanger. The hot water unit serves as a heat source for the melting crystallizer 11 in step 2, and also as a heat source for the refrigeration unit to prepare low-temperature water for the melting crystallizer 11 in step 2. The preparation method of this invention fully utilizes the heat from the crude ethylene carbonate product to recover heat from the hot water transfer unit. The hot water unit exchanges heat with the hot water, with a portion of the hot water used as a heat source for melting crystallization and another portion used as a heat source for the hot water-type lithium bromide refrigerator 9 to prepare low-temperature water for melting crystallization. No additional steam consumption is required, which greatly reduces energy consumption.

[0081] Additionally, it should be noted that each of the aforementioned pipes or channels is equipped with an on / off control valve. In actual implementation, by controlling the opening and closing of the corresponding control valve, the on / off status of the corresponding pipeline can be controlled, thereby controlling the flow direction of the medium in each pipeline.

[0082] specific:

[0083] This invention discloses a purification system for electronic-grade ethylene carbonate, mainly comprising an evaporation unit, a heat conduction unit, and a melt crystallization unit; the evaporation unit is connected to the melt crystallization unit via the heat conduction unit; the evaporation unit includes a scraped film evaporator 2; the melt crystallization unit includes a melt crystallizer 11; the heat conduction unit includes a heat exchange unit and a refrigeration unit; the heat exchange unit includes a hot water conduction unit and a hot water unit; the heat conduction unit is connected to the hot water unit; the evaporation unit is connected to the melt crystallization unit via the hot water conduction unit and the hot water unit; the hot water conduction unit includes a hot water heat exchanger 3; the hot water unit includes a hot water heat exchanger 6; the scraped film evaporator 2 is connected to a catalyst delivery pump 1.

[0084] The present invention discloses the above-mentioned purification system, which is equivalent to using a melt crystallization purification process coupled with a heat recovery system to prepare electronic-grade ethylene carbonate, which has the significant advantages of low energy consumption and high yield of electronic-grade products.

[0085] The present invention provides a method for preparing electronic-grade ethylene carbonate, comprising the following steps:

[0086] (1) The ethylene carbonate reactants were subjected to vacuum distillation in a scraped film evaporator 2 to remove the catalyst and obtain crude ethylene carbonate product.

[0087] (2) The crude ethylene carbonate product is repeatedly crystallized, sweated, and melted in the melt crystallizer 11 to obtain electronic grade ethylene carbonate.

[0088] (3) The crude ethylene carbonate product of step (1) is cooled by a hot water conduction unit. The heated hot water then transfers heat to the hot water unit through a heat exchanger. The hot water unit is used as the heat source for the melt crystallizer 11 in step (2) on the one hand, and the hot water is used as the heat source for the refrigeration unit to prepare low-temperature water for the melt crystallizer 11 in step (2).

[0089] In step (1) above, the purity of the ethylene carbonate reactant is 98.0% to 99.5%.

[0090] In step (1) above, the purity of the crude ethylene carbonate product is 99.0% to 99.9%.

[0091] In step (1) above, the operating temperature of the scraped film evaporator 2 is 100℃~150℃, the pressure is 200PaA~5KPaA, and the steam consumption is 0.5~1.0 tons of steam / ton of product.

[0092] In step (2) above, the operating temperature of the melt crystallizer 11 is 20℃~60℃.

[0093] In step (2) above, the purity of the electronic grade ethylene carbonate is 99.995% to 99.999%.

[0094] In step (2) above, the yield of the electronic grade ethylene carbonate is 75% to 95% of the crude product.

[0095] In step (3) above, the temperature of the hot water supply is 85℃~110℃ and the temperature of the return water is 95℃~120℃.

[0096] In step (3) above, the hot water supply temperature is 70℃~80℃ and the return water temperature is 80℃~90℃.

[0097] In step (3) above, the temperature of the low-temperature water is 12℃~15℃ and the temperature of the return water is 7℃~10℃.

[0098] In step (3) above, the refrigeration unit is a hot water type lithium bromide refrigerator 9.

[0099] The preparation method of this invention fully utilizes the heat from the crude ethylene carbonate product to recover heat from the hot water transfer unit. The hot water transfer unit exchanges heat with the hot water; a portion of the hot water is used as the heat source for melting and crystallization, while the other portion is used as the heat source for a hot water-type lithium bromide refrigerator 9 to prepare low-temperature water for melting and crystallization. No additional steam consumption is required, significantly reducing energy consumption. Furthermore, since the material does not require high-temperature distillation, the problem of increased impurities affecting product purity due to side reactions during high-temperature distillation is avoided. Therefore, the yield of electronic-grade ethylene carbonate is much higher than that of the distillation process.

[0100] The specific implementation method is as follows:

[0101] Example 1

[0102] A method for preparing electronic-grade ethylene carbonate includes the following steps:

[0103] (1) The ethylene carbonate reactant with a purity of 99.0% was subjected to vacuum distillation in a scraped film evaporator 2 to remove the catalyst and obtain crude ethylene carbonate with a purity of 99.5%. The operating parameters of the scraped film evaporator 2 were: temperature of 130℃, pressure of 2KPaA, and steam consumption of 0.6 tons of steam / ton of product.

[0104] (2) The crude ethylene carbonate product is repeatedly crystallized, sweated and melted in the melt crystallizer 11 to obtain electronic grade ethylene carbonate with a purity of 99.999%. The operating parameters of the melt crystallizer 11 are: temperature of 25℃~50℃, and yield of electronic grade ethylene carbonate of 90%.

[0105] (3) The crude ethylene carbonate product from step (1) is cooled by a hot water transfer unit. The heated hot water is then transferred to the hot water unit through a heat exchanger. The hot water unit is used as a heat source for the melt crystallizer 11 in step (2) on the one hand, and as a heat source for the hot water type lithium bromide refrigerator 9 to prepare low-temperature water for the melt crystallizer 11 in step (2). The operating parameters of the heat recovery system are: the water temperature of the hot water is 95℃ and the return water temperature is 110℃, the water temperature of the hot water is 75℃ and the return water temperature is 85℃, and the water temperature of the low-temperature water is 13℃ and the return water temperature is 8℃.

[0106] Example 2

[0107] A method for preparing electronic-grade ethylene carbonate includes the following steps:

[0108] (1) The ethylene carbonate reactant with a purity of 99.2% was subjected to vacuum distillation in a scraped film evaporator 2 to remove the catalyst and obtain crude ethylene carbonate with a purity of 99.7%. The operating parameters of the scraped film evaporator 2 were: temperature of 125℃, pressure of 1KPaA, and steam consumption of 0.5 tons of steam / ton of product.

[0109] (2) The crude ethylene carbonate product is repeatedly crystallized, sweated and melted in the melt crystallizer 11 to obtain electronic grade ethylene carbonate with a purity of 99.999%. The operating parameters of the melt crystallizer 11 are: temperature of 20℃~45℃, and the yield of electronic grade ethylene carbonate is 93%.

[0110] (3) The crude ethylene carbonate product from step (1) is cooled by a hot water transfer unit. The heated hot water is then transferred to the hot water unit through a heat exchanger. The hot water unit is used as the heat source for the melt crystallizer 11 in step (2) on the one hand, and the hot water is used as the heat source for the hot water type lithium bromide refrigerator 9 to prepare low-temperature water for the cold source of the melt crystallizer 11 in step (2). The operating parameters of the heat recovery system are: the water temperature of the hot water is 100℃ and the return water temperature is 115℃, the water temperature of the hot water is 77℃ and the return water temperature is 87℃, and the water temperature of the low-temperature water is 12℃ and the return water temperature is 7℃.

[0111] Example 3

[0112] A method for preparing electronic-grade ethylene carbonate includes the following steps:

[0113] (1) The ethylene carbonate reactant with a purity of 98.9% was subjected to vacuum distillation in a scraped film evaporator 2 to remove the catalyst and obtain crude ethylene carbonate with a purity of 99.3%. The operating parameters of the scraped film evaporator 2 were: temperature of 140℃, pressure of 3KPaA, and steam consumption of 0.7 tons of steam / ton of product.

[0114] (2) The crude ethylene carbonate product is repeatedly crystallized, sweated and melted in the melt crystallizer 11 to obtain electronic grade ethylene carbonate with a purity of 99.996%. The operating parameters of the melt crystallizer 11 are: temperature of 25℃~55℃ and yield of electronic grade ethylene carbonate of 85%.

[0115] (3) The crude ethylene carbonate product from step (1) is cooled by a hot water transfer unit. The heated hot water is then transferred to the hot water unit through a heat exchanger. The hot water unit is used as a heat source for the melt crystallizer 11 in step (2) on the one hand, and as a heat source for the hot water type lithium bromide refrigerator 9 to prepare low-temperature water for the cold source of the melt crystallizer 11 in step (2). The operating parameters of the heat recovery system are: the water temperature of the hot water is 105℃ and the return water temperature is 120℃, the water temperature of the hot water is 72℃ and the return water temperature is 82℃, and the water temperature of the low-temperature water is 15℃ and the return water temperature is 10℃.

[0116] Comparative Example 1

[0117] Using the same ethylene carbonate reactant with a purity of 99.0% as in Example 1, and referring to patent CN113072530A, electronic-grade ethylene carbonate with a purity of 99.996% was obtained through a three-stage distillation process involving a crude ethylene carbonate refining tower, a catalyst recovery tower, and a ethylene carbonate refining tower. The yield of electronic-grade ethylene carbonate was 75%, and the steam consumption was 2.5 tons / ton of product.

[0118] In summary, the preparation method of the present invention makes full use of the heat recovery of crude ethylene carbonate product by the hot water unit, and uses the hot water unit to exchange heat with the hot water. Part of the hot water is used as the heat source for melting and crystallization, and the other part of the hot water is used as the heat source for the hot water type lithium bromide refrigerator 9 to prepare low-temperature water as the cold source for melting and crystallization. No additional steam consumption is required, which greatly reduces energy consumption.

[0119] Meanwhile, since the material does not require high-temperature distillation, it avoids the problem of increased impurities affecting product purity due to side reactions during high-temperature distillation. Therefore, the yield of electronic-grade ethylene carbonate is much higher than that of the distillation process.

[0120] Obviously, the specific implementation of this invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A purification system for electronic-grade ethylene carbonate, characterized in that, It includes an evaporation unit, a heat conduction unit, and a melting and crystallization unit; The evaporation unit is connected to the melting and crystallization unit through a heat-conducting unit; The evaporation unit includes a scraped film evaporator; The melt crystallization unit includes a melt crystallizer; The heat-conducting unit includes a heat exchange unit and a refrigeration unit; The heat exchange unit is connected to the melting and crystallization unit via a refrigeration unit and / or directly; The heat exchange unit includes a hot water transfer unit and a hot water unit; The heat-conducting unit is connected to the hot water unit; The evaporation unit is connected to the melting and crystallization unit via a hot water transfer unit and a hot water unit; the hot water transfer unit includes a hot water heat exchanger; the hot water unit includes a hot water heat exchanger. The heat from the crude ethylene carbonate product is recovered using a hot water transfer unit, and then the hot water is exchanged with the hot water in the hot water transfer unit. The heat absorbed by the heat exchange unit can be used part of the hot water as a heat source for melting and crystallization, and the other part of the hot water can be used as a heat source for a hot water-type lithium bromide refrigerator to prepare low-temperature water as a cold source for melting and crystallization.

2. The purification system for electronic-grade ethylene carbonate according to claim 1, characterized in that; The hot water heat exchanger is connected to the hot water heat exchanger through a first pipeline mechanism; The hot water heat exchanger is connected to the melting and crystallization unit via a second piping mechanism.

3. The purification system for electronic-grade ethylene carbonate according to claim 2, characterized in that; The first pipeline structure includes a first inlet pipe and a first return pipe, and the hot water heat exchanger is connected to the hot water heat exchanger through the first inlet pipe and the first return pipe respectively; A hot water transfer pump is installed on the first water inlet pipe.

4. The purification system for electronic-grade ethylene carbonate according to claim 3, characterized in that; The second pipeline structure includes a primary water supply pipeline and a secondary water supply pipeline, wherein the primary water supply pipeline is connected to the melting crystallizer via a refrigeration unit; The secondary water supply pipeline is connected to the melting crystallizer.

5. A purification system for electronic-grade ethylene carbonate according to any one of claims 1-4, characterized in that; The purification system further includes a hot water storage unit; the hot water storage unit includes a hot water storage tank; a third pipeline mechanism is connected to the hot water storage tank; and a hot water delivery pump is installed on the third pipeline mechanism. The hot water storage tank is connected to the refrigeration unit and the melting and crystallization unit through a third pipeline mechanism.

6. A purification system for electronic-grade ethylene carbonate according to any one of claims 1-4, characterized in that; The purification system also includes a low-temperature water storage unit; the low-temperature water storage unit includes a low-temperature water storage tank, which is connected to a fourth pipeline mechanism; a low-temperature water delivery pump is provided on the fourth pipeline mechanism; The low-temperature water storage tank is connected to the refrigeration unit and the melting and crystallization unit through a fourth pipeline mechanism.

7. A purification system for electronic-grade ethylene carbonate according to any one of claims 1-4, characterized in that; The purification system also includes a material supply unit; the material supply unit includes a crude ethylene carbonate product storage tank; the crude ethylene carbonate product storage tank is connected to the melting and crystallization unit via a crude ethylene carbonate product transfer pump.

8. A method for preparing electronic-grade ethylene carbonate, characterized in that, The preparation method requires the use of the purification system as described in any one of claims 1-7; The preparation method includes the following steps: Step 1: The ethylene carbonate reactants are subjected to vacuum distillation in a scraped film evaporator to remove the catalyst and obtain crude ethylene carbonate product; Step 2: The crude ethylene carbonate product is repeatedly crystallized, evaporated, and melted in a melt crystallizer to obtain electronic grade ethylene carbonate.

9. The method for preparing electronic-grade ethylene carbonate according to claim 8, characterized in that, The crude ethylene carbonate product generated in step 1 is initially cooled by a hot water transfer unit; the hot water transfer unit exchanges heat with the crude ethylene carbonate product from step 1; then the heat is transferred to the hot water unit; the hot water unit then transfers the heat to the refrigeration unit and the melting crystallizer.

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