A kind of power battery grade carboxylate purification equipment of multi-impurity synergistic removal

Abstract

The application relates to the technical field of chemical separation and purification, and discloses a kind of multi-impurity cooperative removal purification equipment of power battery grade carboxylic acid ester, including crystallization outer cylinder, the top of the crystallization outer cylinder is equipped with feed inlet, the bottom of the crystallization outer cylinder is equipped with discharge port, the inside of the crystallization outer cylinder is coaxially movably provided with crystallization inner cylinder, the bottom of the crystallization inner cylinder is conical bottom plate, a plurality of bubble holes are uniformly arranged on the conical bottom plate, and the bottom surface outside of the conical bottom plate is fixedly installed with bottom rotary vane plate.The application can make gas push bottom rotary vane plate to drive crystallization inner cylinder to rotate, form ascending bubble flow in the inside of crystallization inner cylinder through bubble hole and form air floatation support between conical bottom plate and the bottom of crystallization outer cylinder by inputting gas into gas storage space from air inlet, realize three functions of driving, bubbling and friction reduction, simplify equipment structure and reduce energy consumption.

Description

Technical Field

[0001] This invention relates to the field of chemical separation and purification technology, specifically to a multi-impurity synergistic removal and purification device for power battery-grade carboxylic acid esters. Background Technology

[0002] Carboxylic acid esters, such as vinylene carbonate, ethylene carbonate, and dimethyl carbonate, are core components of lithium-ion battery electrolytes. Their purity directly affects the battery's cycle life, safety performance, and energy density. With the rapid development of the new energy vehicle industry, the purity requirements for carboxylic acid esters used in electrolytes are becoming increasingly stringent, and anionic impurities such as chloride ions and sulfates must be controlled to extremely low levels. Currently, industrial purification of carboxylic acid esters mainly employs distillation technology, including atmospheric distillation, vacuum distillation, and extractive distillation. For highly heat-sensitive carboxylic acid esters, falling film crystallization or melt crystallization techniques are used for purification. In recent years, the distillation-melt crystallization coupled process has gradually become the mainstream technical route. This involves first increasing the purity of the crude product to over 90% through distillation, and then further refining it through melt crystallization to obtain a high-purity product.

[0003] However, existing purification technologies still have many shortcomings. Conventional distillation techniques have limited effectiveness in separating impurities with similar boiling points, and their high operating temperatures can easily lead to the decomposition or polymerization of heat-sensitive carboxylic esters, affecting product yield and purity. Existing melt crystallizers suffer from severe scaling and clogging problems during long-term operation. As crystals continuously deposit on the cooling walls and sieve plates, heat transfer efficiency declines continuously, reducing production capacity and sometimes even forcing the unit to be shut down for cleaning. At the same time, high-viscosity materials tend to remain at the bottom of the crystallizer, causing product loss and difficulties in discharge. The crystalline scale layer on the heat exchanger surface can also cause localized overheating, further exacerbating the thermal decomposition of heat-sensitive materials. Summary of the Invention

[0004] In view of the shortcomings of existing melt crystallization purification equipment mentioned in the background art, the present invention provides a multi-impurity synergistic removal and purification equipment for power battery grade carboxylic acid esters, which has the advantages of pneumatic drive and bubbling anti-scaling synergistic effect, and solves the technical problems mentioned in the background art.

[0005] This invention provides the following technical solution: a multi-impurity synergistic removal and purification device for power battery-grade carboxylic acid esters, comprising a crystallization outer cylinder, an inlet at the top of the crystallization outer cylinder, an outlet at the bottom of the crystallization outer cylinder, a crystallization inner cylinder coaxially and movably disposed inside the crystallization outer cylinder, the bottom of the crystallization inner cylinder being a conical bottom plate, a plurality of bubble outlets evenly distributed on the conical bottom plate, a bottom swirl plate fixedly installed on the outer side of the bottom surface of the conical bottom plate, a gas storage space formed between the bottom of the crystallization outer cylinder and the bottom surface of the conical bottom plate, an air inlet connected to the gas storage space at the bottom of the crystallization outer cylinder, a top support frame fixedly installed on the top of the crystallization outer cylinder, a plurality of heat exchange plates fixedly disposed on the top support frame, the plurality of heat exchange plates being interconnected through heat exchange medium pipes, the two ends of the heat exchange medium pipes being respectively connected to heat exchange medium inlets and outlets opened on the crystallization outer cylinder, and a scraper fixedly installed at the bottom of the top support frame, the bottom surface of the scraper being in contact with the top surface of the conical bottom plate.

[0006] Preferably, the bottom surface of the outer crystallizing cylinder is a conical surface, the taper of the conical bottom plate is consistent with the taper of the bottom surface of the outer crystallizing cylinder, the discharge port is opened at the lowest point of the conical surface, and the bottom of the inner crystallizing cylinder is connected to the discharge port.

[0007] Preferably, the inner crystallizing cylinder is a barrel-shaped cylinder with an open top, the axial outer diameter of the inner crystallizing cylinder is smaller than the axial inner diameter of the outer crystallizing cylinder, and the vertical outer wall of the inner crystallizing cylinder is attached to the vertical inner wall of the outer crystallizing cylinder.

[0008] Preferably, the gas storage space is the gap between the bottom inner wall of the outer crystallizer and the bottom surface of the conical base plate, and the lateral gap between the vertical outer wall of the inner crystallizer and the vertical inner wall of the outer crystallizer is smaller than the bottom gap of the gas storage space.

[0009] Preferably, the bottom swivel plate is a turbine blade structure, and the air inlet introduces gas into the gas storage space. The gas pushes the bottom swivel plate to drive the crystallizing inner cylinder to rotate around its axis, while the gas enters the interior of the crystallizing inner cylinder through the bubbling port.

[0010] Preferably, the plurality of bubble openings are evenly distributed on the conical base plate, and the bubble openings connect the gas storage space with the internal space of the crystallization inner cylinder.

[0011] Preferably, the heat exchange plates are arranged in an alternating inclined manner on the top support frame, and a gap is provided between the heat exchange plates and the inner wall of the crystallization inner cylinder to allow material flow.

[0012] Preferably, the heat exchange medium pipe is fixedly installed on the top support frame, with one end of the heat exchange medium pipe connected to the inlet end of the heat exchange medium inlet and outlet, and the other end connected to the outlet end of the heat exchange medium inlet and outlet.

[0013] The top support frame extends from the top of the outer crystallizing cylinder to the bottom of the inner crystallizing cylinder, and the scraper is fixedly installed at the bottom end of the top support frame.

[0014] Preferably, the bottom surface of the scraper is attached to the top surface of the conical bottom plate, and when the crystallizing inner cylinder rotates, the scraper continuously scrapes the top surface of the conical bottom plate.

[0015] The present invention has the following beneficial effects: 1. This invention introduces gas into the gas storage space through the air inlet, which enables the gas to simultaneously drive the bottom swivel plate to rotate the inner crystallizing cylinder, enter the inner crystallizing cylinder through the bubbling port to form an upward bubble flow, and form an air flotation support between the conical bottom plate and the bottom of the outer crystallizing cylinder. This achieves the three functions of driving, bubbling and friction reduction in one gas source and linkage, which simplifies the equipment structure and reduces energy consumption.

[0016] 2. The present invention continuously scrapes the top surface of the conical bottom plate by the scraper when the inner crystallizing cylinder rotates, which can push the crystals deposited at the bottom to the central discharge port in time. At the same time, the slight vibration generated by the sliding friction between the scraper and the conical bottom plate is transmitted to the heat exchange plate through the top support frame, causing the heat exchange plate to vibrate slightly, effectively avoiding the accumulation of crystals on the surface of the heat exchange plate and ensuring the stability of heat exchange efficiency during long-term operation.

[0017] 3. The present invention uses multiple sets of heat exchange plates arranged in an alternating inclined manner on the top support frame, with adjacent heat exchange plates inclined in opposite directions. This allows the molten material entering the crystallization cylinder to flow along the baffle path, prolonging the contact time and heat exchange path between the material and the heat exchange plates, and preventing the material from being discharged directly without sufficient cooling. This significantly improves the crystallization yield and the uniformity of crystal purity.

[0018] 4. This invention connects the two ends of the heat exchange medium pipe to the inlet and outlet ends of the heat exchange medium, respectively, allowing operators to switch the type of heat exchange medium introduced at any time according to process needs. Cooling medium is introduced during the crystallization stage to achieve cooling and crystallization, and heating medium is introduced during the sweating stage to achieve heating and sweating. The two purification processes of crystallization and sweating are completed sequentially in the same equipment, simplifying the operation process and reducing equipment investment costs.

[0019] 5. The present invention adopts a matching conical surface design for the bottom surface of the outer crystallization cylinder and the conical bottom plate of the inner crystallization cylinder, and the discharge port is opened at the lowest point of the conical surface. This allows the molten carboxylic acid ester and mother liquor to smoothly converge to the bottom and be discharged under the action of gravity after crystallization and sweating, avoiding the accumulation and residue of high viscosity materials in the dead corners at the bottom of the equipment. This not only improves the product yield but also reduces the frequency of equipment shutdown for cleaning. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the internal structure of the present invention; Figure 2 This is a vertical sectional view of the overall structure of the present invention; Figure 3 This is a schematic diagram of the bottom structure of the crystallization inner cylinder of the present invention.

[0021] In the diagram: 1. Outer crystallizer cylinder; 11. Feed inlet; 12. Discharge outlet; 13. Heat exchange medium inlet and outlet; 2. Inner crystallizer cylinder; 21. Conical bottom plate; 22. Bubble inlet; 23. Bottom swirl plate; 24. Gas storage space; 25. Gas inlet; 3. Top support frame; 31. Heat exchange plate; 32. Heat exchange medium pipe; 33. Scraper. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figure 1 A multi-impurity synergistic removal and purification device for power battery-grade carboxylic acid esters includes a crystallization outer cylinder 1, which is a vertically arranged cylindrical container with a feed inlet 11 at the center of its top for molten carboxylic acid ester material to enter the device. The bottom surface of the crystallization outer cylinder 1 is conical, and a discharge outlet 12 is located at the bottom of the conical surface. The conical design facilitates the smooth convergence and discharge of material to the bottom under gravity after crystallization, avoiding material accumulation in the dead corners at the bottom.

[0024] An inner crystallizing cylinder 2 is coaxially and movably mounted inside the outer crystallizing cylinder 1. The inner crystallizing cylinder 2 is a barrel-shaped body with an open top, and its axial outer diameter is slightly smaller than the axial inner diameter of the outer crystallizing cylinder 1, allowing the inner crystallizing cylinder 2 to rotate freely around its own axis inside the outer crystallizing cylinder 1. The vertical outer wall of the inner crystallizing cylinder 2 is close to the vertical inner wall of the outer crystallizing cylinder 1, with a small lateral gap between them, serving a radial positioning function. The top of the inner crystallizing cylinder 2 is limited by the top wall of the outer crystallizing cylinder 1, preventing the inner crystallizing cylinder 2 from suspending too high during rotation.

[0025] The bottom of the inner crystallization cylinder 2 is a conical bottom plate 21, the taper of which matches the taper of the bottom surface of the outer crystallization cylinder 1, thus ensuring that the bottom shape of the inner crystallization cylinder 2 matches the bottom shape of the outer crystallization cylinder 1. Multiple bubbling openings 22 are evenly distributed on the conical bottom plate 21 in a circular array. Each bubbling opening 22 is a small hole penetrating the thickness direction of the conical bottom plate 21, with a diameter ranging from 0.5mm to 3mm, preferably 1mm to 2mm. The bubbling openings 22 connect the gas storage space 24 with the internal space of the inner crystallization cylinder 2, allowing gas in the gas storage space 24 to enter the material inside the inner crystallization cylinder 2 through the bubbling openings 22.

[0026] A bottom swivel plate 23 is fixedly installed on the outer side of the bottom surface of the conical base plate 21. The bottom swivel plate 23 has a turbine blade structure, with blades evenly distributed along the circumference of the conical base plate 21. The number of blades is 6-12, preferably 8. The bottom swivel plate 23 is used to drive the crystallizing inner cylinder 2 to rotate under the push of gas.

[0027] A gas storage space 24 is formed between the bottom inner wall of the crystallizing outer cylinder 1 and the bottom surface of the conical bottom plate 21. The gas storage space 24 serves as a gas buffer and distribution area. The lateral gap between the vertical outer wall of the crystallizing inner cylinder 2 and the vertical inner wall of the crystallizing outer cylinder 1 is smaller than the bottom gap of the gas storage space 24, so that the gas in the gas storage space 24 mainly accumulates in the bottom area, with a small amount of lateral leakage, ensuring that the gas can effectively drive the bottom swirl plate 23.

[0028] An air inlet 25 is provided at the bottom of the outer crystallizing cylinder 1, which leads directly to the gas storage space 24 for introducing driving gas into the gas storage space 24. During operation, nitrogen gas, which has been dried and deoxygenated, is introduced into the gas storage space 24 through the air inlet 25 at a pressure of 0.1 MPa-0.5 MPa, preferably 0.2 MPa-0.3 MPa. Part of the nitrogen gas entering the gas storage space 24 drives the bottom swivel plate 23 to rotate the inner crystallizing cylinder 2 around its axis, while the other part enters the interior of the inner crystallizing cylinder 2 through the bubble outlet 22, forming an upward bubble flow. The gas in the gas storage space 24 forms a gas film between the conical bottom plate 21 of the inner crystallizing cylinder 2 and the inner wall of the bottom of the outer crystallizing cylinder 1, reducing the frictional resistance of the inner crystallizing cylinder 2 during rotation and providing air buoyancy support.

[0029] A top support frame 3 is fixedly installed on the top of the outer crystallization cylinder 1. The top support frame 3 is a rigid support structure that extends axially downward from the top center of the outer crystallization cylinder 1 to the bottom area of ​​the inner crystallization cylinder 2. The top end of the top support frame 3 is fixedly connected to the top wall of the outer crystallization cylinder 1, and its main body is located inside the inner crystallization cylinder 2.

[0030] Multiple heat exchange plates 31 are fixedly mounted on the top support frame 3. The heat exchange plates 31 are straight plates made of a metal material with good thermal conductivity, such as stainless steel or copper alloy. The multiple heat exchange plates 31 are arranged in a staggered, inclined manner on the top support frame 3, meaning that the inclination directions of adjacent heat exchange plates 31 are opposite, forming a flow channel structure similar to a baffle plate. A distance of 10mm-50mm, preferably 20mm-30mm, is maintained between the heat exchange plates 31 and the inner wall of the crystallization inner cylinder 2 to allow material flow. The staggered arrangement of adjacent heat exchange plates 31 increases the flow path length of the material inside the crystallization inner cylinder 2, preventing the material from entering through the inlet 11 and being discharged directly from the outlet 12 without sufficient heat exchange, thereby improving the heat exchange effect and crystallization efficiency.

[0031] Multiple heat exchange plates 31 are interconnected via heat exchange medium pipes 32, which are fixedly mounted on the top support frame 3. One end of the heat exchange medium pipe 32 is connected to the inlet end of the heat exchange medium inlet / outlet 13 located on the outer crystallization cylinder 1, and the other end is connected to the outlet end of the heat exchange medium inlet / outlet 13. During operation, the heat exchange medium, such as cooling water, heat transfer oil, or refrigerant, enters the heat exchange medium pipe 32 from the inlet end of the heat exchange medium inlet / outlet 13, flows through the internal channels of each heat exchange plate 31, and is discharged from the outlet end of the heat exchange medium inlet / outlet 13, forming a circulation loop. By switching the type of heat exchange medium (refrigerant or heat medium), the cooling and crystallization or heating and sweating operations of the material inside the inner crystallization cylinder 2 can be achieved.

[0032] A scraper 33 is fixedly installed at the bottom of the top support frame 3, and the scraper 33 is located at the lowest end of the top support frame 3. The bottom surface of the scraper 33 is in contact with the top surface of the conical bottom plate 21, that is, the scraper 33 is in contact with the upper surface of the conical bottom plate 21. When the crystallizing inner cylinder 2 rotates, the scraper 33 remains stationary, and its bottom surface continues to scrape against the top surface of the conical bottom plate 21, pushing the crystals deposited on the surface of the conical bottom plate 21 toward the central area, and finally discharged through the discharge port 12.

[0033] The scraper 33 is made of an elastic, wear-resistant material such as polytetrafluoroethylene or spring steel. During the scraping process, it generates continuous sliding friction with the rotating conical base plate 21, thus producing minute vibrations. These minute vibrations are transmitted to the heat exchange plate 31 through the top support frame 3, causing the heat exchange plate 31 to vibrate slightly. This effectively prevents crystals from accumulating on the surface of the heat exchange plate 31, ensuring that the heat transfer efficiency of the heat exchange plate 31 is always maintained at a high level.

[0034] The side wall of the crystallization outer cylinder 1 is also provided with detection interfaces for installing temperature sensors and pressure sensors, so that operators can monitor the temperature and pressure parameters inside the equipment in real time.

[0035] The working principle of the method of using this invention is as follows: In use, the molten carboxylic acid ester to be purified is added into the crystallization inner cylinder 2 through the feed inlet 11. A cooling medium, such as cooling water or refrigerant, is introduced into the heat exchange plate 31 through the heat exchange medium inlet / outlet 13 to cool the material inside the crystallization inner cylinder 2, lowering its temperature below the freezing point of the target product. The target product gradually crystallizes and precipitates on the surface of the conical bottom plate 21 and the heat exchange plate 31. Simultaneously, nitrogen gas is introduced into the gas storage space 24 through the gas inlet 25. The nitrogen gas pushes the bottom swivel plate 23 to slowly rotate the crystallization inner cylinder 2 at a speed of 0.5 rpm to 5 rpm, preferably 1 rpm to 3 rpm. At the same time, the nitrogen gas enters the crystallization inner cylinder 2 through the bubble outlet 22, forming an upward bubble flow. The bubbles continuously disturb the material, preventing excessive accumulation of crystals on the surface of the conical bottom plate 21 and promoting uniform temperature distribution within the material.

[0036] After crystallization, the heat exchange medium is switched to a heat transfer medium such as hot water or thermal oil to slowly heat the inside of the crystallization cylinder 2. As the temperature rises, the impurity components encapsulated in the crystals melt and liquefy before the target product, forming a sweating liquid rich in impurities. Under the action of gravity, the sweating liquid seeps out from the crystal layer and flows downward, and is discharged through the outlet 12, thereby achieving further separation of impurities from the target product.

[0037] After the sweating process is complete, the temperature continues to rise until the target product is completely melted. The molten liquid is discharged and collected through the outlet 12. During equipment operation, the scraper 33 continuously scrapes the top surface of the conical bottom plate 21 to ensure that no material remains at the bottom.

[0038] Through the above-mentioned crystallization, sweating, and discharge processes, the synergistic removal and purification of multiple impurities in power battery-grade carboxylic acid esters can be achieved.

[0039] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-impurity synergistic removal and purification device for power battery grade carboxylic acid esters, comprising a crystallization outer cylinder (1), wherein a feed inlet (11) is provided at the top of the crystallization outer cylinder (1), and a discharge outlet (12) is provided at the bottom of the crystallization outer cylinder (1), characterized in that: The crystallizing outer cylinder (1) is coaxially and movably provided with a crystallizing inner cylinder (2). The bottom of the crystallizing inner cylinder (2) is a conical bottom plate (21). Multiple bubbling openings (22) are evenly provided on the conical bottom plate (21). A bottom swirl plate (23) is fixedly installed on the outer side of the bottom surface of the conical bottom plate (21). A gas storage space (24) is formed between the bottom of the crystallizing outer cylinder (1) and the bottom surface of the conical bottom plate (21). An air inlet (25) communicating with the gas storage space (24) is provided at the bottom of the crystallizing outer cylinder (1). A top support frame (3) is fixedly installed on the top of the crystallization outer cylinder (1). Multiple heat exchange plates (31) are fixedly installed on the top support frame (3). The multiple heat exchange plates (31) are interconnected through heat exchange medium pipes (32). The two ends of the heat exchange medium pipes (32) are respectively connected to the heat exchange medium inlet and outlet (13) opened on the crystallization outer cylinder (1). A scraper (33) is fixedly installed at the bottom of the top support frame (3). The bottom surface of the scraper (33) is attached to the top surface of the conical bottom plate (21).

2. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: The bottom surface of the outer crystallizing cylinder (1) is a conical surface, and the taper of the conical bottom plate (21) is consistent with the taper of the bottom surface of the outer crystallizing cylinder (1). The discharge port (12) is located at the lowest point of the conical surface, and the bottom of the inner crystallizing cylinder (2) is connected to the discharge port (12).

3. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: The inner crystallizing cylinder (2) is a barrel-shaped cylinder with an open top. The axial outer diameter of the inner crystallizing cylinder (2) is smaller than the axial inner diameter of the outer crystallizing cylinder (1). The vertical outer wall of the inner crystallizing cylinder (2) is attached to the vertical inner wall of the outer crystallizing cylinder (1).

4. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: The gas storage space (24) is the gap between the bottom inner wall of the crystallizing outer cylinder (1) and the bottom surface of the conical bottom plate (21). The lateral gap between the vertical outer wall of the crystallizing inner cylinder (2) and the vertical inner wall of the crystallizing outer cylinder (1) is smaller than the bottom gap of the gas storage space (24).

5. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: The bottom swivel plate (23) is a turbine blade structure. The air inlet (25) introduces gas into the gas storage space (24). The gas pushes the bottom swivel plate (23) to drive the crystallizing inner cylinder (2) to rotate around its axis. At the same time, the gas enters the interior of the crystallizing inner cylinder (2) through the bubble inlet (22).

6. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: Multiple bubble openings (22) are evenly distributed on the conical base plate (21), and the bubble openings (22) connect the gas storage space (24) with the internal space of the crystallization inner cylinder (2).

7. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: Multiple heat exchange plates (31) are arranged in an alternating inclined manner on the top support frame (3), and a gap is provided between the heat exchange plates (31) and the inner wall of the crystallization inner cylinder (2) for material flow.

8. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: The heat exchange medium pipe (32) is fixedly installed on the top support frame (3). One end of the heat exchange medium pipe (32) is connected to the inlet end of the heat exchange medium inlet / outlet (13), and the other end is connected to the outlet end of the heat exchange medium inlet / outlet (13).

9. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: The top support frame (3) extends from the top of the outer crystallization cylinder (1) to the bottom of the inner crystallization cylinder (2), and the scraper (33) is fixedly installed at the bottom end of the top support frame (3).

10. The multi-impurity synergistic removal and purification equipment for power battery-grade carboxylic acid esters according to claim 1, characterized in that: The bottom surface of the scraper (33) is attached to the top surface of the conical bottom plate (21). When the crystallizing inner cylinder (2) rotates, the scraper (33) continuously scrapes the top surface of the conical bottom plate (21).

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