Melt crystallization apparatus

Abstract

The application belongs to the technical field of material purification, and particularly relates to a melting crystallization device, which comprises a crystallization section I, a crystallization section II, a sweating section and a melting section, the crystallization section II is communicatively arranged at the top of the sweating section, the crystallization section II is internally provided with a downcomer, the crystallization section I is communicated with the upper end of the downcomer through a pipeline, the lower end of the downcomer is arranged towards the bottom of the crystallization section II, the melting section is communicatively arranged at the bottom of the sweating section, the bottom of the melting section is communicated with the crystallization section I through a pipeline, the connection part of the crystallization section II and the sweating section is provided with an inlet port one, the inlet port one is communicated with the sweating section through a pipeline and / or connected with a gas supply unit, the connection part of the sweating section and the melting section is provided with an inlet port two, the inlet port two is communicated with the melting section through a pipeline and / or connected with the gas supply unit, the purification processing capacity of the device is faster, the efficiency and the production capacity are improved, the flowability of the device is better, and no or fewer internal components are needed, so that the overall amplification and continuous operation of the device can be facilitated.

Description

Technical Field

[0001] This invention belongs to the technical field of material purification, specifically relating to a melting crystallization device. Background Technology

[0002] Crystallization refers to the process by which a substance forms crystals from a liquid (solution or molten state) or gaseous state. Crystallization is an important method for purifying solid substances and plays a crucial role in product separation and purification processes. Based on the means of generating supersaturation, crystallization can be classified into four categories: cooling crystallization, precipitation crystallization, sublimation crystallization, and melt crystallization.

[0003] Melt crystallization is a purification method that separates different substances through solid-liquid two-phase equilibrium based on the differences in their melting points. Melt crystallization offers advantages such as low operating temperature, fewer side reactions, low energy consumption, environmental friendliness, and high purity of the separated product. It is suitable for special substances (such as materials with similar boiling points, isomers, heat-sensitive substances, chiral substances, substances with high boiling points, and dilute solutions). Current melt crystallization methods typically include three steps: crystallization, sweating, and melting.

[0004] Existing melt crystallization devices mostly use unidirectional flow tower crystallizers, which have the following problems:

[0005] (1) The limited space inside the tower, which is shared by the crystallization zone, sweating zone, and melting zone, results in a small crystallization space, low crystallization amount, low crystallization rate, and low production capacity. Increasing the tower diameter or height will increase the crystallization space. However, since heat is transferred from the outside to the inside of the tower, increasing the tower diameter will lead to uneven mass and heat transfer across the cross-section. To achieve the separation and purification goal, it is necessary to add a stirrer to improve the uniformity of mass and heat transfer. The crystals have strong adhesion, and some crystals easily adhere to the stirrer, solidify, and form scale, causing blockage and making stirring difficult. At the same time, the crystals cannot settle normally into the melting zone, affecting the purification efficiency. Increasing the height inside the tower will lengthen the crystal settling process. During the settling process, the crystals are prone to agglomerate and solidify, causing blockage and affecting the flowability, thus affecting the purification efficiency.

[0006] (2) In conventional tower crystallizers, crystals generally settle freely, resulting in a relatively slow settling rate and low efficiency. Furthermore, the crystal bed in the sweating zone lacks a supporting structure, preventing significant adhesion and support, making it prone to collapse and affecting the normal purification process, thus reducing purification efficiency. While supporting the crystal bed with an internal sieve plate can prevent collapse, crystals can only pass through the sieve holes, significantly reducing flowability. Due to the strong adhesion of the crystals, it is difficult for crystal particles to pass through the sieve holes and settle into the melting zone, resulting in low purification efficiency. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a melt crystallization device that improves purification efficiency and production capacity, has better device flowability, requires no or only fewer internal components, and facilitates overall device scaling-up and continuous operation.

[0008] The present invention includes a crystallization section I, a crystallization section II, a sweating section, and a melting section. The crystallization section II is connected to the top of the sweating section and has a downcomer inside. The crystallization section I is connected to the upper end of the downcomer through a pipe, and the lower end of the downcomer is positioned towards the bottom of the crystallization section II. The melting section is connected to the bottom of the sweating section and is connected to the crystallization section I through a pipe. A power pump is installed on the pipe connecting the bottom of the melting section to the crystallization section I. An inlet is provided at the connection between the crystallization section II and the sweating section. The inlet is connected to the sweating section and / or to a gas supply unit through a pipe. An inlet is provided at the connection between the sweating section and the melting section. The inlet is connected to the melting section and / or to a gas supply unit through a pipe.

[0009] Furthermore, several liquid-passing pipes are arranged along the height direction within the crystallization section I. When the fluid enters the crystallization section I along the pipes, it flows into the several liquid-passing pipes and flows out along the several liquid-passing pipes towards the crystallization section II. Moreover, the fluid is in a turbulent state when it flows into the several liquid-passing pipes.

[0010] Furthermore, a discharge port is provided below the inlet port 1 on the sweating section, and the discharge port 1 is connected to the inlet port 1 through a pipe. A discharge port 2 is provided below the inlet port 2 on the melting section, and the discharge port 2 is connected to the inlet port 2 through a pipe. A circulation pump is provided on both the pipe connecting the discharge port 1 to the inlet port 1 and the pipe connecting the discharge port 2 to the inlet port 2.

[0011] Furthermore, the gas supply unit is a vacuum pump, and the first and second inlets are connected to the exhaust end of the vacuum pump through pipes, while the suction end of the vacuum pump is connected to the crystallization section II.

[0012] Furthermore, the upper end of the downcomer extends to the outside of the crystallization section II and is connected to an inlet chamber. The suction end of the vacuum pump is connected to the inlet chamber through a pipe, and the side of the inlet chamber is connected to the upper end of the crystallization section II through a pipe, thereby connecting the suction end of the vacuum pump to the crystallization section II.

[0013] Furthermore, the pipe connecting the bottom of the melting section to the crystallization section I has one end connected to the bottom of the melting section that is horizontally positioned relative to the bottom of the melting section. The bottom of the melting section is also provided with an air inlet, which is connected to the exhaust end of the vacuum pump through a pipe.

[0014] Furthermore, the crystallization section II is provided with a mother liquor outlet, which is connected to the bottom of the melting section and the crystallization section I via a pipe, thereby connecting the mother liquor outlet and the bottom of the melting section and the crystallization section I. The connection point between the mother liquor outlet and the pipe connecting the bottom of the melting section and the crystallization section I is located between the crystallization section II and the power pump.

[0015] Furthermore, the crystallization section II is provided with an overflow port, which is located above the mother liquor outlet in the height direction of the crystallization section II.

[0016] Furthermore, on the pipe connecting the bottom of the melting section to the crystallization section I, the area between the bottom of the melting section and the power pump forms a U-shape with the melting section, and the end of the U-shaped area near the power pump is lower than the discharge port II.

[0017] Furthermore, the inner wall at the connection between the crystallization section II and the sweating section, as well as the inner wall at the connection between the sweating section and the melting section, are both radially extended to form an inner diameter contraction section.

[0018] The beneficial effects of this invention are that the overall structure is a circulating flow type, and the crystallization section I is separated from the sweating section. This allows for an increase in the space of the crystallization section I without increasing the overall height of the device, resulting in a greater amount of crystals generated. Simultaneously, the temperature of the crystallization section I has less influence on the temperatures of other sections, allowing for more flexible temperature control and facilitating segmented temperature control, thus improving the crystal formation rate. An inlet is provided at the connection between the crystallization section II and the sweating section, and another inlet is provided at the connection between the sweating section and the melting section. This allows for the introduction of airflow and / or liquid flow streams, which support and counter-currently wash the crystal bed in the crystallization section II and the sweating section. This prevents the collapse of the crystal bed without the need for internal components such as sieves and does not reduce flowability. Simultaneously, the introduction of fluid can disturb the crystal bed in the crystallization section II and the sweating section, causing it to boil dynamically. This reduces the possibility of the crystal bed sticking to the walls and clogging, ensuring the relative independence between crystal particles within the bed. This results in a stable and high porosity within the crystal bed, guaranteeing efficient heat and mass transfer. It also eliminates the need for a stirring mechanism, allowing for greater space utilization within the device. For the same external volume, the internal crystallization space is larger, and it avoids the problems of clogging and poor flow caused by internal components such as stirring mechanisms. Furthermore, because this device has better flowability and requires no or fewer internal components, it facilitates overall scale-up and continuous operation. The downcomer in crystallization section II creates a water hammer effect on the crystal bed as the crystal suspension in crystallization section I flows through and out of the downcomer. This increases the downward force field, causing the crystals to fall continuously and at an accelerated rate. Simultaneously, due to efficient mass and heat transfer, the evaporation rate of the particles in the crystal bed increases. The incoming airflow and / or liquid flow creates an upward flow field within the device, increasing the internal reflux rate of the crystal bed. As the fluid moves upward, it carries away the mother liquor coating the crystal particles more quickly, enhancing countercurrent washing, accelerating the evaporation process, and promoting faster discharge of the mother liquor from the overflow port, thus improving the purity of the liquid phase inside the device. The rising airflow and / or liquid flow, along with the sinking crystal particles, creates a simultaneous upward and downward acceleration field, accelerating the purification capacity of the entire device and significantly improving efficiency and production capacity. Attached Figure Description

[0019] Appendix Figure 1 This is a schematic diagram of the first configuration method of the present invention.

[0020] Appendix Figure 2 This is a schematic diagram of the second configuration method of the present invention.

[0021] Appendix Figure 3 This is a schematic diagram of the third configuration method of the present invention.

[0022] Appendix Figure 4The velocity contour plot of several liquid-passing pipes inside crystallization section I when V2 = 0.2 m / s.

[0023] Appendix Figure 5 for Figure 4 The velocity vector diagram at point A in the middle, magnified.

[0024] Appendix Figure 6 The velocity contour plot is the overall velocity of the second configuration of the melting and crystallization device when V2 = 0.2 m / s.

[0025] Appendix Figure 7 for Figure 6 The velocity vector diagram at point B in the middle.

[0026] Appendix Figure 8 for Figure 6 The velocity vector diagram at point C (enlarged view).

[0027] Appendix Figure 9 The velocity contour plot is the overall velocity of the melting and crystallization device in the third configuration when V2 = 0.2 m / s.

[0028] Appendix Figure 10 for Figure 9 The velocity vector diagram at point D in the middle.

[0029] Appendix Figure 11 for Figure 9 The velocity vector diagram at point E in the middle, magnified.

[0030] Appendix Figure 12 for Figure 9 The velocity vector diagram at point F in the middle.

[0031] In the diagram: 1-Crystallization section I; 11-Cooling pipe; 12-Liquid pipe; 2-Crystallization section II; 21-Mother liquor outlet; 22-Overflow port; 3-Sweating section; 31-Outlet 1; 32-Inlet 1; 4-Melting section; 41-Outlet 2; 42-Inlet 2; 5-Downcomer; 51-Liquid inlet chamber; 6-Power pump; 7-Inlet; 8-Circulation pump; 9-Gas supply unit. Detailed Implementation

[0032] As attached Figure 1-3As shown, this invention provides a melting crystallization apparatus, which includes a crystallization section I1, a crystallization section II2, a sweating section 3, and a melting section 4. The crystallization section II2 is located at the top of the sweating section 3 and communicates with the interior of the sweating section 3. A downcomer 5 is provided inside the crystallization section II2, with its axis arranged along the height direction of the crystallization section II2. The crystallization section I1 is connected to the upper end of the downcomer 5 through a pipe, allowing the crystal suspension in the crystallization section I1 to enter the downcomer 5 through this pipe. The lower end of the downcomer 5 is positioned towards the bottom of the crystallization section II2. The melting section 4 is located at the bottom of the sweating section 3 and communicates with the interior of the sweating section 3. The bottom of the melting section 4 is connected to the crystallization section I1 through a pipe, forming a circulating connection structure. A power pump 6 is installed on the pipe connecting the bottom of the melting section 4 to the crystallization section I1 for transporting the crystal liquid in the melting section 4 to the crystallization section I4. An inlet 32 ​​is provided at the connection between the crystallization section II2 and the sweating section 3. The inlet 32 ​​is connected to the sweating section 3 and / or to the gas supply unit 9 through a pipe. An inlet 42 is provided at the connection between the sweating section 3 and the melting section 4. The inlet 42 is connected to the melting section 4 and / or to the gas supply unit 9 through a pipe.

[0033] The invention also includes a feed inlet 7, which is located on the crystallization section I1 or on a pipe connecting the bottom of the melting section 4 to the crystallization section I1, for conveying the material to be purified into the crystallization section I1. The crystallization section I1, the sweating section 3, and the melting section 4 are covered by water bath jackets to control the temperature required by each unit. When the inlet 32 ​​is connected to the sweating section 3 via a pipe, the sweating section 3 has an outlet 31 on its side, and the inlet 32 ​​is connected to the outlet 31 via a pipe. When the inlet 42 is connected to the melting section 4 via a pipe, the melting section 4 has an outlet 41 on its side, and the outlet 42 is connected to the outlet 41 via a pipe. The outlet 41 also discharges the high-purity target product. Since the crystallization section I1 has a large volume and the crystallization section II2 has a large demand for crystals, if the water bath jacket cannot meet the target requirements, cooling pipes 11 are arranged on the side wall of the crystallization section I1 and a cold source is introduced to meet its target cooling requirements.

[0034] When using this melting crystallization device, feed begins from inlet 7. Once the entire device is filled with material, the cooling water bath in crystallization section I1 is turned on. After cooling for a certain period, the material reaches its melting point and begins to gradually form crystals. Once the amount of crystals reaches the target range, the power pump 6 is turned on to circulate the material within the device. The circulation direction of the material is as follows: Figures 1-3The direction indicated by the middle arrow. The crystal suspension in crystallization section I1 gradually enters the downcomer 5 of crystallization section II2 along the pipe, and enters the bottom of crystallization section II5 along the downcomer 5. The crystals slowly accumulate from bottom to top to form a bed. The mother liquor rises from the bottom and passes through the crystal bed. Some small-sized crystal particles rise with the mother liquor to the top of the crystal bed, while larger particles are floated to the bottom of the crystal bed, forming a particle size classification. After eliminating supersaturation in the crystal bed, the mother liquor rises to the top of the crystal bed to form a clarification section. The slightly higher concentration of the target purified mother liquor at the bottom of the clarification section flows into crystallization section I1 from the mother liquor outlet 21 for the next cycle, while the low concentration of the target purified mother liquor overflows from the overflow outlet 22. The crystals in crystallization section II2 slowly fall into sweating section 3, and the thick crystal slurry settles into sweating section 3. Some of it then sinks to melting section 4. Due to the adhesion of the crystals, some crystals also settle to the bottom of the sweating tube and adhere to it. From this point, the crystals begin to accumulate. The crystal bed slowly accumulates from bottom to top in sweating section 3 (under the action of gravity, the bed density shows a gradient distribution from bottom to top, from high to low). During this process: ① While the crystal bed sweats in sweating section 3, the sweating liquid in sweating section 3 is transported from outlet 31 along the pipe from inlet 31 to the interior of the connection between crystallization section II2 and sweating section 3. A liquid stream is formed at the bottom of the crystal bed in crystallization section II2, which affects the crystals in crystallization section II2. The bed layer forms an upward supporting force, while some of the sweat moves upward to wash away the sweat from the surface of the crystal particles, accelerating the sweating process. Finally, it enters the crystallization section II2 and plays the same role as the aforementioned mother liquor; or ② the gas supply unit 9 delivers gas to the inlet 31 through the pipeline, forming an airflow stream that forms an upward supporting force on the crystal bed layer in the crystallization section II2. As the airflow stream rises, it washes away the sweat from the surface of the crystal particles, accelerating the sweating process; or ③ the liquid flow stream and the airflow stream proceed simultaneously, forming a gas-liquid flow stream that forms an upward supporting force on the bed layer in the crystallization section II2. As the gas-liquid flow stream rises, it washes away the sweat from the surface of the crystal particles, accelerating the sweating process.

[0035] In the sweating section 3, the dense crystal layer at the bottom of the crystal bed comes into direct contact with the slightly higher-temperature liquid phase in the melting section 4, melts, and enters the melting section 4 to form a high-concentration quasi-product. When the crystal bed in the sweating section 3 accumulates to a certain height: ① Part of the molten crystal liquid in the melting section 4 is transported from the discharge port 2 41 along the pipeline from the inlet port 2 42 to the interior of the connection between the sweating section 3 and the melting section 4, forming a liquid stream at the bottom of the crystal bed in the sweating section 3; or ② The gas supply unit 9 supplies gas through the pipeline along the inlet port 2 42 to the interior of the connection between the sweating section 3 and the melting section 4, forming an airflow stream at the bottom of the crystal bed in the sweating section 3; or ③ The airflow stream and the liquid stream occur simultaneously; thus, an upward supporting force is formed on the crystal bed in the sweating section 3, providing a certain degree of protection against collapse. In the aforementioned liquid and / or air streams, the liquid and / or air flows upwards, scouring the crystals at the bottom of the crystal bed in the sweating section 3. This causes some crystal particles to settle into the melting section 4. Due to the relatively high temperature in the melting section 4, the crystals melt quickly, resulting in a higher concentration in the melting section 4. Meanwhile, some of the upward-flowing fluid experiences reduced resistance after scouring, while others continue to rise, creating a counter-current washing effect on the crystal bed and promoting the upward flow and discharge of the sweating liquid. The washed impurity mother liquor flows upwards into the crystallization section II2 and finally exits from the overflow port. The concentration in the sweating section 3 and the melting section 4 continues to increase. The liquid phase in the melting section 4 is then pumped to the crystallization section I1 by the power pump 8. Here, the high-concentration liquid phase quickly crystallizes into a large number of crystals in the crystallization section I1, resulting in higher crystal purity. The crystals then flow through pipes and downcomers 5 into the crystallization section II2. This cycle repeats until the purity of the liquid phase in each section reaches a peak and forms a dynamic equilibrium. At this point, the high-purity product is discharged through the discharge port 41, and the feed rate is increased through the inlet 7, forming a continuous process. Considering the structural complexity, when liquid flow and air flow can meet the operational requirements separately, one can be used. When liquid flow cannot meet the operational requirements, liquid flow and air flow can be used in combination. The specific setting method can be determined according to the actual target requirements.

[0036] Unlike traditional unidirectional flow tower crystallizers, the melting crystallization device of this invention features an overall circulating flow structure. The crystallization section I1 is separated from the sweating section 3, allowing for increased space in the crystallization section I1 without increasing the overall height of the device, resulting in a greater crystal production. Simultaneously, the temperature of the crystallization section I1 is less affected by the temperatures of other sections, allowing for more flexible temperature control and facilitating segmented temperature management, thus improving the crystal formation rate. An inlet 31 is provided at the connection between the crystallization section II2 and the sweating section 3, and an inlet 41 is provided at the connection between the sweating section 3 and the melting section 4. This allows for the introduction of airflow and / or liquid flow streams, which support and counter-currently wash the crystal bed within the crystallization section II2 and the sweating section 3. This prevents the collapse of the crystal bed without the need for internal components such as sieves and does not reduce flowability. Simultaneously, the introduction of fluid can disturb the crystal bed in crystallization section II2 and sweating section 3, causing it to boil dynamically. This reduces the possibility of the crystal bed sticking to the walls and clogging, ensuring the relative independence between crystal particles within the bed. This results in a stable and high porosity within the crystal bed, guaranteeing efficient heat and mass transfer. It also eliminates the need for a stirring mechanism, allowing for greater space utilization within the device. With the same external volume, the internal crystallization space is larger, and it avoids the problems of clogging and poor flow caused by internal components such as stirring mechanisms. Furthermore, because this device has better flowability and requires no or fewer internal components, it facilitates overall scale-up and continuous operation. The placement of downcomer 5 within crystallization section II2 creates a water hammer effect on the crystal bed when the crystal suspension in crystallization section I1 flows through and out of downcomer 5. This increases the downward force field, causing the crystals to fall continuously and accelerating their descent. Simultaneously, due to efficient mass and heat transfer, the evaporation rate of particles within the crystal bed increases. The incoming airflow and / or liquid flow creates an upward flow field within the device, increasing the internal reflux rate within the crystal bed. As the fluid moves upward, it carries away the mother liquor coating the crystal particles more quickly, enhancing countercurrent washing, accelerating the evaporation process, and promoting faster discharge of the mother liquor from overflow port 22, thus improving the purity of the liquid phase within the device. The rising airflow and / or liquid flow, along with the sinking crystal particles, creates a simultaneous upward and downward acceleration field during operation, accelerating the purification capacity of the entire device and significantly improving efficiency and production capacity.

[0037] In this invention, a discharge port 31 is provided below the inlet 32 ​​on the sweating section 3, and the discharge port 31 is connected to the inlet 32 ​​via a pipe. A discharge port 41 is provided below the inlet 42 on the melting section 4, and the discharge port 41 is connected to the inlet 42 via a pipe. A circulation pump 8 is provided on both the pipe connecting the discharge port 31 to the inlet 32 ​​and the pipe connecting the discharge port 41 to the inlet 42, to provide power for the flow of sweating liquid in the sweating section 3 from the discharge port 31 to the inlet 31 and for the flow of molten liquid in the melting section 4 from the discharge port 41 to the inlet 42. Among them, the pipe connecting the discharge port 31 to the inlet 32 ​​is also connected to the discharge pipe 1. Under certain operating requirements, the sweating liquid in the sweating section 3 can be discharged to the outside through the discharge port 31 along the discharge pipe 1. The pipe connecting the discharge port 41 to the inlet 42 is also connected to the discharge pipe 2. The high-purity target product can be discharged to the outside through the discharge port 32 along the discharge pipe 2.

[0038] The gas supply unit 9 is a vacuum pump. The inlet 32 ​​and the inlet 42 are connected to the exhaust end of the vacuum pump through pipes. The suction end of the vacuum pump is connected to the crystallization section II2 through a pipe. The gas inside the device is used for airflow circulation. The gas inside the device is an inert gas, such as nitrogen.

[0039] The upper end of the downcomer 5 extends to the outside of the crystallization section II2 and is connected to an inlet chamber 51. The inner diameter of the inlet chamber 51 is larger than that of the downcomer 5. The suction end of the vacuum pump is connected to the inlet chamber 51 through a pipe, and the side of the inlet chamber 51 is connected to the upper end of the crystallization section II2 through a pipe, thus connecting the suction end of the vacuum pump to the crystallization section II2. By setting the inlet chamber 51, the crystal suspension entering the downcomer 5 can be temporarily stored and buffered. At the same time, the inlet chamber 51 and the downcomer 5 form a funnel structure, which facilitates the downward flow of the crystal suspension. Extending the upper end of the downcomer 5 to the outside of the crystallization section II2, the inlet chamber 51 does not occupy the internal space of the crystallization section II2, and it is also convenient to connect to the pipe. Based on the setting of the inlet chamber 51, the inlet chamber 51 is connected to the upper end of the crystallization section II2 through a gas guide pipe, and the vacuum pump is connected to the inlet chamber 51 through a pipe, thus connecting to the crystallization section II2.

[0040] refer to Figure 1-3As shown, the pipe connecting the bottom of the melting section 4 to the crystallization section I1 has one end connected to the bottom of the melting section 4 horizontally relative to the bottom of the melting section 4. The bottom of the melting section 4 also has an air inlet, which is connected to the exhaust end of the vacuum pump via a pipe. When airflow is introduced into the bottom of the melting section 4, part of the airflow can push the molten liquid towards the power pump 8 along the pipe connecting the bottom of the melting section 4 to the crystallization section I1, reducing the power consumption of the power pump 8. Part of the airflow flows upward into the melting section 4, creating disturbance and making the molten liquid in the melting section 4 more uniformly mixed. Then, part of the airflow flows upward sequentially into the sweating section 3 and the crystallization section II2, playing the same role as the aforementioned fluid, further enhancing the purification capacity of the device.

[0041] When the vacuum pump is working, it draws air from the suction end, creating a negative pressure inside the device. The inert gas inside rises, passes through the sweating section 3 and crystallization section II 2, and is then extracted along the downcomer 5. The inert gas extracted by the vacuum pump is then sent back into the device through the exhaust end via inlet 32 ​​and inlet 42, respectively, continuously rising and circulating. This rising inert gas forms the aforementioned airflow stream, which washes over the crystal particles, thereby enhancing the countercurrent washing effect and accelerating sweating. Furthermore, a gas replenishment port can be installed on the pipe connected to the vacuum pump's exhaust or suction end. When the amount of gas inside the device is insufficient to meet the target airflow circulation, some inert gas is added through the replenishment port.

[0042] The crystallization section II2 is equipped with a mother liquor outlet 21, which is connected to the crystallization section I1 via a pipeline. After the mother liquor in the crystallization section II2 is desaturated in the crystal bed, it rises above the crystal bed to form a clarification section. At the bottom of the clarification section, a slightly higher concentration of the target purified mother liquor flows from the mother liquor outlet 21 into the crystallization section I1 for the next cycle, thus improving the utilization rate of the mother liquor.

[0043] refer to Figure 1-3 As shown, the mother liquor outlet 21 is connected to the bottom of the melting section 4 via a pipe that connects to the crystallization section I1, thus communicating with the crystallization section I1. The connection point between the mother liquor outlet 21 and the crystallization section I1 is located between the crystallization section II2 and the power pump 6, allowing the mother liquor to be transported to the crystallization section I1 along the pipe under the action of the power pump 6. Preferably, a one-way valve is installed on the pipe connected to the mother liquor outlet 21 to prevent backflow of the liquid.

[0044] An overflow port 22 is provided on the crystallization section II2. Since the low-concentration target purification mother liquor will float on the upper layer under density stratification, and the higher-concentration target purification mother liquor will be located in the lower layer, it is preferable that the overflow port 22 is located above the mother liquor outlet 21 in the height direction of the crystallization section II2, so that mother liquors of different concentrations can flow out from the mother liquor outlet 21 and the overflow port 22 respectively.

[0045] refer to Figure 3 As shown, on the pipe connecting the bottom of the melting section 4 to the crystallization section I1, the area between the bottom of the melting section 4 and the power pump 6 forms a U-shape with the melting section 4, and the end of this U-shaped area near the power pump 6 is lower than the discharge port 41. The U-shaped area design causes the molten liquid in the melting section 4 to encounter a certain resistance when entering the crystallization section I1, reducing the possibility of the molten liquid naturally flowing to the crystallization section I1 without the action of the power pump 8, resulting in product waste.

[0046] The inner wall at the connection between the crystallization section II2 and the sweating section 3, and the inner wall at the connection between the sweating section 3 and the melting section 4, are both radially extended to form an inner diameter contraction section. The inner diameter contraction section at the connection between the bottom of the crystallization section II2 and the sweating section 3 not only facilitates the crystal settling in the lower half of the crystallization section II2 and the accumulation of the crystal bed, but also makes it easier for the circulating liquid and airflow to form liquid and air resistance to support the crystal bed and prevent it from collapsing. Furthermore, this inner diameter contraction section prevents the incoming airflow or liquid flow from being excessively resisted and sprayed upwards, thus increasing local backmixing. It prolongs the residence time of the crystals and mother liquor, allowing the upward circulating airflow or liquid flow to wash away the mother liquor coating the crystal surface as much as possible, accelerating sweating and making the crystals falling into the lower section purer. The inner diameter contraction section at the connection between the sweating section 3 and the melting section 4 facilitates crystal sedimentation in the lower half of the sweating section 3, promotes crystal bed accumulation, and allows the circulating liquid and gas flows to create liquid and gas resistances to support the crystal bed, preventing crystal bed collapse and avoiding the problem of sparse crystal bed or unstable bed height in the sweating section 3 due to large temperature differences in the melting section 4. This ensures the stability of continuous operation of the device.

[0047] In one embodiment of the present invention, the inner diameter of the crystallizing segment II2 is larger than the inner diameter of the sweating segment 3, and the inner diameter of the sweating segment 3 is larger than the inner diameter of the melting segment 4. That is, the inner diameters of the crystallizing segment II2, the sweating segment 3, and the melting segment 4 are arranged in descending order, so that the connection between the crystallizing segment II2 and the sweating segment 3, and the connection between the sweating segment 3 and the melting segment 4 are arranged in a contracted shape, thereby forming the aforementioned inner diameter contraction segment. In another embodiment of the present invention, the inner diameters of the crystallizing segment II2, the sweating segment 3, and the melting segment 4 may be the same, and are only arranged in a contracted shape at the connection between the crystallizing segment II2 and the sweating segment 3, and the connection between the sweating segment 3 and the melting segment 4, thereby forming the aforementioned inner diameter contraction segment.

[0048] Several liquid-passing pipes 12 are arranged along the height direction within the crystallization section I1, such as... Figures 1-3As shown, the lower ends of several liquid-passing pipes 12 are connected to the pipes leading from the melting section 4 to the crystallization section I1, and the lower ends of several liquid-passing pipes 12 are connected to the pipes leading from the crystallization section I1 to the downcomer 5. This ensures that when the material fluid enters the crystallization section I1 along the pipes, it flows into the several liquid-passing pipes 12 and flows out along the several liquid-passing pipes 12 towards the crystallization section II2. That is, after entering the crystallization section I1, the fluid flows along the several liquid-passing pipes 12, and the fluid is in a turbulent state when it flows into the several liquid-passing pipes 12. When the fluid is in a turbulent state, the mass transfer and heat transfer efficiency is higher, ensuring that the crystallization efficiency of the fluid in the crystallization section I1 meets the requirements, and ensuring that the fluid contains crystals before flowing to the downcomer 5, and that the solid content of the crystals is less than 30%. Within the crystallization section I1, several liquid-passing pipes 12 are arranged to facilitate fluid flow. Since the cross-sectional area of ​​a single liquid-passing pipe 12 is smaller than that of the crystallization section I1, the temperature difference from the center to the edge of the liquid-passing pipe 12 is smaller, resulting in more uniform heat exchange and facilitating crystal precipitation. In this arrangement, to ensure the effectiveness of the cold source cooling, cooling pipes 11 are specifically arranged around the outside of the several liquid-passing pipes 12 on the crystallization section I1.

[0049] Based on the above device design, according to the Reynolds number Re=ρvd / μ, a Re>4000 is required to achieve turbulent flow inside the pipe. A mixture of o-cresol and p-cresol (mass ratio of 20% o-cresol and 80% p-cresol) was used as the test fluid for simulation testing at 30℃. When Re is 4000, nine liquid-passing pipes 12 were selected, with a diameter d1 of 60 mm for each pipe and a flow velocity v1=0.06699 m / s inside. The diameter d2 of the pipe between the power pump 6 and the crystallization section I1 was 113.73 mm, with a flow velocity v2=0.03534 m / s inside.

[0050] According to the law of flow conservation: V1×πr1 2 ×9=V²×πr² 2 Where r1 is the radius of the liquid pipe 12, V1 is the fluid velocity in the liquid pipe 12 that satisfies flow conservation, r2 is the radius of the pipe between the power pump 6 and the crystallization section I1, and V2 is the fluid velocity in the pipe that satisfies flow conservation. When V1 = 0.06699 m / s, V2 = 0.1678 m / s, which is greater than 0.03534 m / s. It can be considered that under this flow velocity, the liquid pipe 12 and the pipe between the power pump 6 and the crystallization section I1 both satisfy turbulent flow.

[0051] Simulations were performed with V2 = 0.2 m / s, such as... Figure 4 The figure shown is a velocity contour map of several liquid-passing pipes 12 within the crystallization section I1 under this velocity simulation. Figure 5 The velocity vector diagram of a local area in one of the liquid passage pipes 12 shows that turbulent flow exists, meeting the requirements. For example... Figure 6The image shown is a velocity contour plot of the second configuration of the present invention (without a U-shaped section between the melting section 4 and the power pump 6) at this speed. Figure 7 for Figure 6 Local velocity vector diagram within the intermediate crystallization segment II2, Figure 8 for Figure 6 The local velocity vector diagram at the connection point between the mother liquor outlet 21 and the pipe connecting the melting section 4 and the crystallization section I1 shows that turbulent flow exists, meeting the requirements. Figure 9 The image shown is a velocity contour plot of the third configuration of the present invention (a U-shaped section is provided between the melting section 4 and the power pump 6) at this speed. Figure 10 for Figure 9 Local velocity vector diagram within the intermediate crystallization segment II2, Figure 11 for Figure 9 A local velocity vector diagram of the U-shaped region near the end of power pump 6. Figure 12 for Figure 9 The local velocity vector diagram at the connection point between the mother liquor outlet 21 and the melting section 4 and the crystallization section I1 shows that turbulent flow exists, which meets the requirements.

[0052] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0053] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A melt crystallization apparatus characterized by, The crystallization section I (1), the crystallization section II (2), the sweating section (3) and the melting section (4) are arranged in sequence, the crystallization section II (2) is arranged on the top of the sweating section (3), the crystallization section II (2) is internally provided with a downcomer (5), the crystallization section I (1) is communicated with the upper end of the downcomer (5) through a pipeline, the lower end of the downcomer (5) is arranged towards the bottom of the crystallization section II (2), the melting section (4) is arranged on the bottom of the sweating section (3), and the bottom of the melting section (4) is communicated with the crystallization section I (1) through a pipeline, a power pump (6) is arranged on the pipeline, which is communicated with the crystallization section I (1) and located at the bottom of the melting section (4), an inlet one (32) is arranged at the joint of the crystallization section II (2) and the sweating section (3), the inlet one (32) is communicated with the sweating section (3) and / or connected with a gas supply unit (9) through a pipeline, an inlet two (42) is arranged at the joint of the sweating section (3) and the melting section (4), the inlet two (42) is communicated with the melting section (4) and / or connected with the gas supply unit (9) through a pipeline. A plurality of liquid passing pipes (12) are arranged in the crystallization section I (1) along the height direction, when the fluid enters the crystallization section I (1) through the pipeline, the fluid flows into the plurality of liquid passing pipes (12) and flows out of the plurality of liquid passing pipes (12) towards the crystallization section II (2), and the fluid flows into the plurality of liquid passing pipes (12) in a turbulent flow state. A mother liquor outlet (21) and an overflow port (22) are arranged on the crystallization section II (2), the mother liquor outlet (21) is connected with the pipeline, which is communicated with the crystallization section I (1) and located at the bottom of the melting section (4), so as to be communicated with the crystallization section I (1), and the position, at which the mother liquor outlet (21) is connected with the pipeline, which is communicated with the crystallization section I (1) and located at the bottom of the melting section (4), is located between the crystallization section II (2) and the power pump (6), and the overflow port (22) is located above the mother liquor outlet (21) in the height direction of the crystallization section II (2).

2. The melt crystallization apparatus of claim 1 wherein, An outlet one (31) is arranged below the inlet one (32) on the sweating section (3), the outlet one (31) is communicated with the inlet one (32) through a pipeline, an outlet two (41) is arranged below the inlet two (42) on the melting section (4), the outlet two (41) is communicated with the inlet two (42) through a pipeline, and a circulating pump (8) is arranged on the pipeline, which is communicated with the inlet one (32) and the outlet two (41).

3. The melt crystallization apparatus of claim 1 or 2, wherein The gas supply unit (9) is a vacuum pump, the inlet one (32) and the inlet two (42) are connected with the exhaust end of the vacuum pump through a pipeline, and the suction end of the vacuum pump is communicated with the crystallization section II (2).

4. The melt crystallization apparatus of claim 3 wherein, The upper end of the downcomer (5) extends to the outside of the crystallization section II (2) and is communicated with a liquid inlet cavity (51), the suction end of the vacuum pump is communicated with the liquid inlet cavity (51) through a pipeline, and the side of the liquid inlet cavity (51) is communicated with the upper end of the crystallization section II (2) through a pipeline, so that the suction end of the vacuum pump is communicated with the crystallization section II (2).

5. The melt crystallization apparatus of claim 3 wherein the melt crystallization apparatus is a melt crystallization apparatus as defined in any one of claims 1 to 2. The pipeline of the bottom of the melting section (4) communicating with the crystallization section I (1) is transversely arranged relative to the bottom of the melting section (4) at the end connected with the bottom of the melting section (4), and the bottom of the melting section (4) is further provided with an air inlet connected with the exhaust end of the vacuum pump through the pipeline.

6. The melt crystallization apparatus of any one of claims 1, 2, 4, 5, wherein The region between the bottom of the melting section (4) and the power pump (6) on the pipeline of the bottom of the melting section (4) communicating with the crystallization section I (1) forms a U shape with the melting section (4), and the end of the U shape region close to the power pump (6) is lower than the second discharge port (41) in height.

7. The melt crystallization apparatus of any one of claims 1, 2, 4, 5, wherein The inner side walls of the connection between the crystallization section II (2) and the sweating section (3) and the connection between the sweating section (3) and the melting section (4) are radially extended to form inner diameter contraction sections.

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