Ultrasonic-cold finger coupled plate-type melt crystallizer and continuous purification process

Abstract

The ultrasonic-cold finger coupling type plate-type melt crystallizer comprises a crystallizer body, a plurality of heat exchange plates are arranged in the crystallizer body, and a snakelike refrigerant channel is arranged in each heat exchange plate; the ultrasonic vibration pieces are sequentially arranged on the periphery of a shell plate of the plate-type melt crystallizer and used for providing an ultrasonic field covering a whole crystallizer body; and the at least one cold finger assembly is arranged at the top of the plate-type melt crystallizer and is connected with the upper cover plate of the crystallizer body through a detachable flange. The cold finger assembly comprises an inlet header, an outlet header, a cold finger body and an ultrasonic probe. The inlet header and the outlet header are arranged above the crystallizer body in parallel in the second direction. The bottom of each cold finger body is arranged in the crystallizer body, and the two ends of the top of each cold finger body are communicated with the inlet header and the outlet header respectively. The ultrasonic probe extends in the third direction and is inserted into the cold finger body. By means of the melt crystallizer and the process, the crystallization efficiency is higher, and the product yield is larger.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of melt crystallization separation and purification equipment, and particularly relates to an ultrasonic-cold finger coupled plate melt crystallizer and a continuous purification process. BACKGROUND

[0002] The existing ultrasonic technology is widely used in solution crystallization, but there are the following problems in melt crystallization. First, the existing cold finger technology can locally strengthen cooling, but a thick crystal layer is easily formed on the surface of the cold finger, the thermal resistance rapidly increases, and the adhesion between the crystal and the wall surface of the cold finger is high, which is difficult to peel off. Second, the cavitation-microjet effect of ultrasonic in the crystallization process can promote nucleation and inhibit scaling, but a single ultrasonic transducer has fast energy attenuation and a limited action area, and it is difficult to be efficiently coupled with a plate crystallizer. SUMMARY

[0003] The present application provides an ultrasonic-cold finger coupled plate melt crystallizer to solve the problem of fast energy attenuation and limited action area of a single ultrasonic transducer in the prior art, which is difficult to be efficiently coupled with a plate crystallizer.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is to provide an ultrasonic-cold finger coupled plate melt crystallizer, which comprises: A crystallizer body extending along a first direction, which is composed of a plurality of parallel heat exchange plates, and each heat exchange plate is internally provided with a serpentine refrigerant channel.

[0005] A plurality of ultrasonic vibration pieces arranged around the shell plate of the plate melt crystallizer in sequence, for providing an ultrasonic field covering the entire crystallizer body.

[0006] At least one cold finger assembly arranged at the top of the plate melt crystallizer and connected with the upper cover plate of the crystallizer body through a detachable flange.

[0007] The cold finger assembly comprises an inlet header, an outlet header, a cold finger body and an ultrasonic probe. The inlet header and the outlet header are arranged in parallel above the crystallizer body along the second direction.

[0008] The bottom of each cold finger body is arranged in the crystallizer body, and the two ends of the top are respectively communicated with the inlet header and the outlet header. The ultrasonic probe extends along a third direction and is inserted into the cold finger body.

[0009] An external junction box is used to uniformly access and control the ultrasonic probe and the plurality of ultrasonic vibration pieces.

[0010] The ultrasonic-cold finger coupled plate type melt crystallizer provided by the application can provide an ultrasonic field covering the whole crystallizer body through multiple ultrasonic vibration sheets arranged around the shell plate of the plate type melt crystallizer, and the cavitation effect of ultrasonic waves can generate a local high-temperature and high-pressure environment in the solution, and when the cavitation bubbles collapse, strong micro-jets are generated, which can break the static balance of the solution and help solute molecules reach the crystallization interface more quickly, thereby accelerating the crystallization process.

[0011] Preferably, the acoustic intensity of the ultrasonic vibration sheet is 0.1-0.5 W·cm -2 , and the frequency is 20-50 kHz. The frequency of the ultrasonic probe is 20-50 kHz.

[0012] Preferably, the cold finger body comprises an inlet section, a U-shaped section, an outlet section and a quick connection clamp, the inlet section and the outlet section are arranged on both sides of the top of the U-shaped section along the first direction, and are both arranged in smooth connection with the U-shaped section. One end of the inlet section away from the U-shaped section is connected with the inlet header, and one end of the outlet section away from the U-shaped section is connected with the outlet header. The quick connection clamp is arranged at one end of the inlet section close to the inlet header and one end of the outlet section close to the outlet header.

[0013] Preferably, the ultrasonic probe is arranged in the U-shaped section correspondingly, and the insertion depth is 80-120 mm, and the drift diameter of the ultrasonic probe is 1-2 mm smaller than the drift diameter of the U-shaped section.

[0014] Preferably, the cold finger assembly further comprises a temperature sensor, the temperature sensor is arranged in the outlet header, and the insertion depth corresponds to the center position of the outlet header, for real-time monitoring of the outlet temperature of the cold finger assembly.

[0015] Preferably, the ultrasonic probe and the ultrasonic vibration sheet operate in a pulse-intermittent mode, the pulse time t1 is 0.5-3 s, the intermittent time t2 is 2-8 s, and the micro-vibration with an amplitude of 10-50 μm is generated on the surface of the cold finger. Therefore, under the joint action of the ultrasonic probe and the ultrasonic vibration sheet located inside and outside the cold finger, the micro-vibration generated on the surface of the cold finger can ensure that the fragments after the crystal layer is broken are uniformly distributed, and local over-dense or over-dilute crystal nuclei are avoided.

[0016] The technical scheme adopted by the application further comprises a continuous purification process applied to the ultrasonic-cold finger coupled plate type melt crystallizer described in the above various embodiments, which comprises the following steps: The precooling-ultrasonic pre-nucleation stage: the cold finger body is cooled to Tc=Tf-(8-12) ℃, and at the same time, the ultrasonic wave is 20 kHz, 0.3-0.5 W·cm -2Continuous action, microcrystalline nucleus is generated inside the melt, wherein Tc is the cold finger temperature, and Tf is the melt crystallization temperature.

[0017] Rapid growth phase of crystal layer: the ultrasonic is turned off, the cold finger assembly continues to cool to Tc=Tf-(15-18) ℃, and a 0.5-1 mm crystal layer is formed.

[0018] Ultrasonic-cold finger resonance crystal breaking and regenerating phase: the ultrasonic is turned on again, the ultrasonic frequency is adjusted to match the inherent frequency of the cold finger body, the cold finger body surface vibrates slightly and makes the crystal layer break and regenerate.

[0019] Sweating-ultrasonic synergistic impurity removal phase: stop the ultrasonic, heat to Tc=Tf-(2-4) ℃ at 0.5 ℃ / min, open the ultrasonic for 1 second every 30 seconds, and the pulse intensity is 2 W·cm -2 The mother liquor enriched on the surface of the crystal layer is squeezed out.

[0020] Final melting-collection phase: heat to Tf+2 ℃, melt the crystal layer and collect the product.

[0021] Compared with the prior art, the ultrasonic-cold finger coupled plate type melt crystallizer provided by the application has the beneficial effects brought by the cold finger-ultrasonic synergy: High-frequency micro-vibration is introduced at the initial stage of crystal layer formation, the adhesion of the crystal to the wall surface is reduced, the overgrowth of the crystal is inhibited in line, and the thin crystal layer is maintained; The microcrystals are stripped by ultrasonic cavitation, the thin crystal layer on the surface of the cold finger is maintained, the crystal scar is continuously stripped without mechanical crystal scraping, and the heat transfer is continuously strengthened; The size and morphology of the crystal are precisely controlled by the adjustable ultrasonic field, and the product purity and yield are improved.

[0022] Further, the ultrasonic is turned on again, the ultrasonic frequency is adjusted to match the inherent frequency of the cold finger body, the cold finger body surface vibrates slightly and makes the crystal layer break and regenerate. The ultrasonic probe and the ultrasonic vibration piece operate in pulse-intermittent mode, the pulse time t1 is 0.5-3 s, the intermittent time t2 is 2-8 s, the cold finger surface produces micro-vibration with an amplitude of 10-50 µm, and the van der Waals force between the crystal and the wall surface is weakened.

[0023] The cavitation jet impacts and shears the shaken crystal layer and dendrite from the side and the inside, and forms 1-50 µm fragments.

[0024] The fragments are instantaneously captured by the supercooled melt near the surface of the cold finger, become new crystal nuclei and continue to grow.

[0025] Further, the ultrasonic is turned on again, the ultrasonic frequency is adjusted to match the inherent frequency of the cold finger body, the cold finger body surface vibrates slightly and makes the crystal layer break and regenerate. -2The mother liquor enriched on the surface of the crystal layer is squeezed out, including: The cold finger body is slowly heated, and the intercrystalline impurity mother liquor begins to melt to form a liquid film, but is bound between the crystals by capillary force.

[0026] Every 30 seconds, the ultrasonic system independently emits a 1-second high-intensity pulse and impacts the entire crystal layer, squeezing out or shaking off the intercrystalline impurity liquid film and discharging it into the main body of the mother liquor.

[0027] Further, the pre-cooling-ultrasonic pre-nucleation stage, the crystal layer rapid growth stage, the ultrasonic-cold finger resonance crystal breaking regeneration stage, the sweating-ultrasonic synergistic impurity removal stage and the final melting-collection stage are in a continuous working mode, and the total working time includes: the processing time of the pre-cooling-ultrasonic pre-nucleation stage is 0-30s, the processing time of the crystal layer rapid growth stage is 30s-5min, the processing time of the ultrasonic-cold finger resonance crystal breaking regeneration stage is 5-15min, the processing time of the sweating-ultrasonic synergistic impurity removal stage is 15-20min, and the processing time of the final melting-collection stage is 15-20min. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor based on these drawings. Figure 1 is a perspective view of an ultrasonic-cold finger coupled plate type melt crystallizer provided by the present application; Figure 2 is a schematic view of a cold finger assembly in an ultrasonic-cold finger coupled plate type melt crystallizer provided by the present application; Figure 3 is a schematic view of the inlet section and outlet section of the cold finger assembly in an ultrasonic-cold finger coupled plate type melt crystallizer provided by the present application; Figure 4 is a partial structure schematic view of an ultrasonic-cold finger coupled plate type melt crystallizer provided by the present application; Figure 5 is an initial 1h crystallization state diagram of material A using a conventional plate type melt crystallization method in mode one; Figure 6 is an initial 1h crystallization state diagram of material A using a cold finger device crystallization method alone in mode two; Figure 7 is an initial 1h crystallization state diagram of material A using a cold finger-ultrasonic crystallization method in mode three; Figure 8 isFigure 5 Chromatogram of the finished product corresponding to the intermediate crystallization state; Figure 9 for Figure 6 Chromatogram of the finished product corresponding to the intermediate crystallization state; Figure 10 for Figure 7 Chromatogram of the finished product corresponding to the intermediate crystallization state. Detailed Implementation

[0029] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] refer to Figures 1 to 10 , Figure 1 This is a perspective view of an ultrasonic-cold finger coupling plate melt crystallizer 1 provided by the present invention; Figure 2 This is a schematic diagram of the cold finger assembly in an ultrasonic-cold finger coupled plate melt crystallizer 1 provided by the present invention; Figure 3 This is a schematic diagram of the inlet and outlet sections of the cold finger assembly in an ultrasonic-cold finger coupled plate melt crystallizer provided by the present invention; Figure 4 This is a partial structural schematic diagram of an ultrasonic-cold finger coupling plate melt crystallizer 1 provided by the present invention; Figure 5 This is a diagram of the initial 1-hour crystallization state of material A using the conventional plate melt crystallization method (Method 1). Figure 6 This is a diagram showing the initial 1-hour crystallization state of material A using the cold fingering device alone in method two; Figure 7 This is a diagram of the initial 1-hour crystallization state of material A using the three-cold finger-ultrasonic crystallization method; Figure 8 for Figure 5 Chromatogram of the finished product corresponding to the intermediate crystallization state; Figure 9 for Figure 6 Chromatogram of the finished product corresponding to the intermediate crystallization state; Figure 10 for Figure 7 Chromatogram of the finished product corresponding to the intermediate crystallization state.

[0031] like Figures 1 to 4 As shown, the technical solution provided in this application is an ultrasonic-cold finger coupling plate melt crystallizer 1, comprising: Crystallizer body 2, along the first direction ( Figure 1 Extending in the X direction, the interior consists of multiple parallel heat exchange plates, each with a built-in serpentine refrigerant channel.

[0032] A plurality of ultrasonic vibration pieces 40 are arranged around the shell plate of the plate-type melt crystallizer 1 in sequence to provide an ultrasonic field covering the entire crystallizer body 2.

[0033] At least one cold finger assembly is arranged at the top of the plate-type melt crystallizer 1 and connected to the upper cover plate of the crystallizer body 2 through a detachable flange. In this embodiment, two sets of cold finger assemblies (A / B) are arranged at the top of the crystallizer body 2, and the two sets of cold finger assemblies are used alternately. After a plurality of batches are run by the cold finger assembly A group, the cold finger assembly B group is switched, and the cold finger assembly A group is lifted out as a whole for cleaning, so that the cold finger assembly can be switched during the feeding process and lifted out as a whole for cleaning during use, thereby improving the working efficiency of the melt crystallizer 1.

[0034] The cold finger assembly includes an inlet header 30, an outlet header 31, a cold finger body 32, and an ultrasonic probe 33. The inlet header 30 and the outlet header 31 are arranged in parallel above the crystallizer body 2 along a second direction (indicated by the Y direction in the middle). Figure 1

[0035] The bottom of each cold finger body 32 is arranged in the crystallizer body 2, and the two ends of the top are in communication with the inlet header 30 and the outlet header 31, respectively. The ultrasonic probe 33 extends along a third direction (indicated by the Z direction in the middle) and is inserted into the cold finger body 32. Figure 1

[0036] An external junction box 4 is used to uniformly access and control the ultrasonic probe 33 and the plurality of ultrasonic vibration pieces 40.

[0037] The plate-type melt crystallizer 1 provided by the present application can provide an ultrasonic field covering the entire crystallizer body 2 by arranging a plurality of ultrasonic vibration pieces 40 around the shell plate of the plate-type melt crystallizer 1 in sequence. The cavitation effect of ultrasonic waves can generate a local high-temperature and high-pressure environment in the solution. When the cavitation bubbles collapse, strong micro-jets are generated, which can break the static balance of the solution and help the solute molecules reach the crystallization interface more quickly, thereby accelerating the crystallization process. The external junction box 4 is used to uniformly access and control the ultrasonic probe 33 and the plurality of ultrasonic vibration pieces 40. This integrated control method can realize accurate adjustment of ultrasonic energy. The operator can flexibly adjust the vibration frequency and amplitude of the ultrasonic vibration pieces 40 and the power of the ultrasonic probe 33 and other parameters through the external junction box 4 according to different crystallization materials and process requirements. The cold finger body 32 can guide the crystallization direction, so that the crystals grow around the cold finger in a certain direction, thereby obtaining regular crystal shapes.

[0038] In some embodiments, the acoustic intensity of the ultrasonic vibration piece 40 is 0.1-0.5 W·cm -2 ​​The frequency of the ultrasonic probe 33 is 20-50 kHz.

[0039] The sound intensity range is set to 0.1-0.5 W·cm -2 The frequency range of 20-50 kHz is the best frequency range for ultrasonic waves to propagate in a liquid and produce cavitation effects, which can produce strong micro-jets and local high-temperature and high-pressure environments, helping solute molecules to reach the crystallization interface more quickly.

[0040] In some embodiments, referring to Figures 1 to 4 The cold finger body 32 includes an inlet section 34, a U-shaped section 35, an outlet section 36, and a quick coupling clamp 38. The inlet section 34 and the outlet section 36 are respectively arranged on both sides of the top of the U-shaped section 35 and are smoothly connected with the U-shaped section 35. One end of the inlet section 34 away from the U-shaped section 35 is connected with the inlet header 30, and one end of the outlet section 36 away from the U-shaped section 35 is connected with the outlet header 31. The quick coupling clamp 38 is respectively arranged at one end of the inlet section 34 close to the inlet header 30 and one end of the outlet section 36 close to the outlet header 31.

[0041] The inlet section 34 and the outlet section 36 are respectively arranged on both sides of the top of the U-shaped section 35, which allows the refrigerant to be evenly distributed to each part of the U-shaped section 35. After the refrigerant enters the U-shaped section 35 from the inlet section 34, it flows along the inner wall of the U-shaped section 35 and can fully contact the heat source inside the crystallizer. The quick coupling clamp 38 is respectively arranged at one end of the inlet section 34 close to the inlet header 30 and one end of the outlet section 36 close to the outlet header 31. This design of the quick coupling clamp 38 makes the installation and removal of the cold finger body 32 more convenient and fast.

[0042] In some embodiments, referring to Figures 1 to 4 The ultrasonic probe 33 is arranged in the U-shaped section 35, and the insertion depth is 80-120 mm. The passage diameter of the ultrasonic probe 33 is 1-2 mm smaller than the passage diameter of the U-shaped section 35, which ensures that the installation of the ultrasonic probe 33 does not interfere, and a gap greater than 3 mm cannot guarantee the ultrasonic effect.

[0043] The insertion depth of the ultrasonic probe 33 into the U-shaped section 35 is 80-120 mm, which ensures that the ultrasonic energy can accurately act on the crystallization area inside the U-shaped section 35, promoting the movement of solute molecules and the crystallization process.

[0044] In some embodiments, referring to Figures 1 to 4The cold finger assembly further comprises a temperature sensor 37, which is arranged in the outlet header 31 and inserted to a position corresponding to the center of the outlet header 31, for monitoring the outlet temperature of the cold finger assembly in real time.

[0045] By arranging the temperature sensor 37 in the outlet header 31, the temperature change during the crystallization process can be monitored in real time, so that the crystallization process can be more accurately controlled. The temperature sensor 37 is inserted to a position corresponding to the center of the outlet header 31, which can ensure that the temperature measured by the sensor more accurately reflects the actual outlet temperature of the cold finger assembly. The temperature sensor 37, the ultrasonic probe 33 and the ultrasonic vibration piece 40 are all explosion-proof, and the explosion-proof level is Exd-IIB-T4.

[0046] The technical scheme provided in the present application further comprises a continuous purification process applied to the ultrasonic-cold finger coupled plate type melt crystallizer 1 described in the above embodiments, which comprises the following steps: Step S01: pre-cooling-ultrasonic pre-nucleation stage: the cold finger body 32 is cooled to Tc=Tf-(8-12) ℃, and the ultrasonic wave is applied at 20 kHz, 0.3-0.5 W·cm -2 continuously generates microcrystal nuclei in the melt, wherein Tc is the temperature of the cold finger, and Tf is the crystallization temperature of the melt.

[0047] By using deep supercooling to provide strong nucleation driving force (ΔG∝ΔT) and ultrasonic cavitation to generate 10 2 -10 3 microcrystal nuclei in the melt, this stage is critical for pre-nucleation, which makes the subsequent steps no longer rely on primary nucleation, avoids excessive local supercooling and mother liquor inclusion, improves the final purity, and makes the subsequent growth no longer rely on random and uncontrollable primary nucleation. This avoids the extreme supercooling condition set for inducing nucleation, thereby reducing the mother liquor inclusion caused by explosive nucleation and rapid growth from the source.

[0048] Step S02: crystal layer rapid growth stage: the ultrasonic wave is turned off, the cold finger assembly is continuously cooled to Tc=Tf-(15-18) ℃, and a 0.5-1 mm crystal layer is formed.

[0049] By turning off the ultrasonic wave on the basis of a large number of crystal nuclei, a quiet laminar flow growth environment is created, and impurities are left on the mother liquor side by using the “thin crystal layer-high heat transfer” state. At this time, since there are many crystal nuclei, the space for each crystal nucleus to grow is limited, thereby naturally forming a thin crystal layer, and the growth stage maintains laminar flow, reduces inter-crystal entrainment, and improves the primary purity. Under the driving of a high temperature gradient (large temperature difference between the two ends of the thin crystal layer), heat is quickly removed, and the crystal grows rapidly but orderly. The key to this stage is to utilize the pre-nucleation results to achieve controllable rapid growth.

[0050] Step S03: Ultrasonic-cold finger resonance crystal breaking and regrowth stage: restart the ultrasonic, the ultrasonic frequency is adjusted to match the natural frequency (usually 20-40 kHz) of the cold finger body 32, the surface of the cold finger body 32 vibrates slightly and makes the crystal layer break and regenerate.

[0051] Illustratively, the ultrasonic matching frequency makes the cold finger surface produce accurate micro-vibration of 10-50 μm, when the amplitude is less than 10 μm, the surface displacement is too small, the inertial force and shear stress are not enough to overcome the van der Waals adsorption potential of the crystal-wall, and when the amplitude is greater than 50 μm (too long), the surface displacement is too large, the crystal is "shaken off" or slips as a whole, and the supercooled region, while the energy dissipation increases, resulting in local temperature rise. Further, the huge shear force of the cavitation microjet directly breaks the grown dendrite arms, and the 1-50 μm fragments are instantly captured by the surrounding supercooled melt to become new perfect crystal nuclei, forming a positive feedback cycle of breaking-providing crystal nuclei-regrowth. The crystal layer formed by the re-stacking of microcrystals is much denser than the dendritic layer grown freely, with fewer defects and voids, and shorter impurity diffusion paths, laying a solid foundation for subsequent sweating.

[0052] Step S04: sweating-ultrasonic synergistic impurity removal stage: stop the ultrasonic, and heat up to Tc=Tf-(2-4) °C at a rate of 0.5 °C / min, turn on the ultrasonic for 1 second every 30 seconds, and the pulse intensity is 2 W·cm -2 The mother liquor enriched on the surface of the crystal layer is squeezed out.

[0053] Illustratively, the essence of sweating is to melt and remove the intercrystalline residual mother liquor rich in impurities by slowly heating, and the high-intensity short-pulse ultrasonic produces extremely strong instantaneous vibration, which effectively overcomes the capillary force and squeezes out the impurity liquid film from the crystal layer like a vibrating sieve, which is a mechanical force-assisted mass transfer process, greatly improving the sweating efficiency and impurity removal effect.

[0054] Step S05: final melting and collection stage: heat up to Tf+2 °C, melt the crystal layer and collect the product.

[0055] Illustratively, this stage is a conventional operation, but due to the optimization of the previous steps, the final yield and purity are significantly improved. By strictly synchronizing the rhythm of "ultrasonic on-off-pulse" with the rhythm of "cold finger cooling-constant temperature-heating", the product purity and yield can be improved at the two key nodes of "crystal breaking and refining" and "sweating and impurity removal".

[0056] In some embodiments, referring to Figures 1 to 4 Restarting the ultrasonic, adjusting the ultrasonic frequency to match the natural frequency of the cold finger body 32, and making the crystal layer break and regenerate include: The ultrasonic probe 33 and the ultrasonic vibration piece 40 operate in a pulse-intermittent mode, the pulse time t1 = 0.5~3s, the intermittent time t2 = 2-8s, the cold finger surface generates micro-vibration of 10~50μm amplitude, and the van der Waals force between the crystal and the wall surface is weakened.

[0057] The cavitation jet impacts and shears the crystal layer and dendrites that have been shaken loose from the side and the inside, forming 1~50µm fragments.

[0058] The fragments are instantaneously captured by the supercooled melt near the cold finger surface to become new crystal nuclei and continue to grow.

[0059] Exemplarily, the micro-vibration generated by the cold finger surface can ensure uniform distribution of the fragments after the crystal layer is broken, avoiding local over-dense or over-dilute crystal nuclei. Such uniform distribution helps the uniform growth of the subsequent crystal layer, improves the crystallization quality, and makes the size distribution of the crystal more uniform. Deep supercooling reduces the thermodynamic energy barrier, and the cavitation micro-disturbance provides additional nucleation sites, and the superposition of the two makes the nucleation rate increase by 2~3 orders of magnitude, while the shear force generated by cavitation continuously peels off the primary crystal nuclei, prevents the crystal layer from excessive thickening, and maintains the cold finger surface in a thin crystal layer-high heat transfer state. The thinner the crystal layer, the smaller the thermal resistance, and the more heat can be transferred per unit time, thereby maintaining a higher crystallization rate. This is because the thermal resistance is proportional to the thickness: the thermal conductivity of the crystal layer itself is much lower than that of the metal wall surface, and once the thickness increases, the thermal resistance rises rapidly, the heat transfer efficiency decreases, and the temperature gradient is larger: the temperature difference between the two ends of the thin crystal layer is large, the heat flux is high, and the heat can be quickly transferred from the melt to the cooling wall. The crystallization rate is controlled by heat transfer: the melting and crystallization is a "heat transfer dominated" process, and the heat must be removed in time to allow the crystal to continue to grow. In the thin layer state, heat transfer is not a bottleneck, and crystallization can continue rapidly. In the secondary nucleation stage, the cavitation jet breaks the formed dendrites into a large number of microcrystal fragments, which are captured again by the cold finger supercooled layer as new crystal nuclei, realizing "continuous regenerative crystal nuclei", further refining the crystal grains, and reducing the particle size distribution In some embodiments, with reference to Figures 1 to 4 , stop the ultrasonic, and increase the temperature to Tc=Tf-(2~4)℃ at a rate of 0.5℃ / min, turn on the ultrasonic for 1s every 30s, and the pulse intensity is 2W·cm -2 Extruding the mother liquor enriched on the surface of the crystal layer includes: The cold finger body 32 is slowly warmed up, and the mother liquor of the intergranular impurities begins to melt to form a liquid film, but is bound between the crystals by capillary force.

[0060] Every 30 seconds, the ultrasonic system independently emits a high-intensity pulse of 1s, and impacts the entire crystal layer, extruding or shaking out the liquid film of impurities between the crystal gaps, and discharging it into the mother liquor body.

[0061] Exemplarily, the periodic ultrasonic pulses can effectively break the binding of capillary force, squeeze or shake the impurity liquid film out of the crystal layer, and improve the impurity removal efficiency. Meanwhile, the ultrasonic system independently emits high-intensity pulses, which can ensure that the entire crystal layer is uniformly subjected to ultrasonic action. This uniform treatment method can avoid local under-treatment or over-treatment, and improve the uniformity and consistency of impurity removal.

[0062] In some embodiments, with reference to Figures 1 to 4 , the pre-cooling-ultrasonic pre-nucleation stage, the crystal layer rapid growth stage, the ultrasonic-cold finger resonance crystal breaking regeneration stage, the sweating-ultrasonic synergistic impurity removal stage and the final melting-collection stage are in continuous working mode. The total working time includes: the processing time of the pre-cooling-ultrasonic pre-nucleation stage is 0-30s, the processing time of the crystal layer rapid growth stage is 30s-5min, the processing time of the ultrasonic-cold finger resonance crystal breaking regeneration stage is 5-15min, the processing time of the sweating-ultrasonic synergistic impurity removal stage is 15-20min, and the processing time of the final melting-collection stage is 15-20min.

[0063] Exemplarily, the pre-cooling-ultrasonic pre-nucleation stage, the crystal layer rapid growth stage, the ultrasonic-cold finger resonance crystal breaking regeneration stage, the sweating-ultrasonic synergistic impurity removal stage and the final melting-collection stage are in continuous working mode. Each stage is seamlessly connected, reducing the operation interruption time and improving the overall production efficiency.

[0064] Further, with reference to Figures 5 to 10 , three groups of comparative experiments were conducted using material A to test the conventional plate-type melt crystallization process, the cold finger device alone, and the cold finger-ultrasonic crystallization process: The first group used the conventional plate-type melt crystallization process, which controlled the temperature in the plate to crystallize, sweat and melt to complete the purification of the material. The initial feed was 6.53 kg, the raw material content was 93.10%, the batch time was 20h, the crystallization time was 12h, the yield was 45.48%, and the product content was 99.11% (see Figure 8 ).

[0065] The initial feed temperature of this group in the crystallization stage was 110℃, which was maintained for one hour to completely melt. The initial crystallization temperature was set to 84℃, and after the appearance of crystals, the temperature was reduced to 82℃, and the crystallization stage lasted for 12 hours. The setting temperature of the sweating stage was 91.5℃, and the duration was 6h. The setting temperature of the melting stage was 110.0℃, and the duration was 1h. The data is shown in Table 1, and the crystallization 1h state is shown in Figure 5 .

[0066] The second group started the cold finger device of the plate-type melt crystallization. The initial feed was 6.14 kg, the product was 2.91 kg, the yield was 47.39%, and the product content was 99.36% (see Figure 9), batch time 17h, crystallization time 11h, the setting temperature of the cold finger device is lower than the crystallization temperature of the material T-5℃ (T is the crystallization temperature of the material), the cold finger device region forms a supercooling zone, and the crystallization state after crystallization for 1h can be observed as shown in Figure 6 It can be seen that the crystallization state is better than that without using the cold finger device.

[0067] The initial feeding temperature of the crystallization stage of this group is 110℃, and it is kept for one hour to completely melt. The initial crystallization temperature is set to 85℃, and then it is continuously cooled to 84℃. After the appearance of crystals, it is cooled to 82℃. The crystallization stage lasts for 11 hours, and the temperature is raised to 84℃ during the mother liquor discharge process. The setting temperature of the sweating stage is 91.5℃, and the duration is 4h. The setting temperature of the melting stage is 110.0℃, and the duration is 1h. The data summary is shown in Table 1, and the crystallization state after 1h is shown in Figure 6 .

[0068] The third group uses a cold finger. The initial feeding is 4.91kg, the finished product is 2.5kg, the yield is 50.92%, and the finished product content is 99.25% (see Figure 10 ). The batch time is 14h, the crystallization time is 9h, and the setting temperature of the cold finger is T-5℃. At the same time, the ultrasonic vibration sheet 40 around the crystallizer and the ultrasonic probe 33 inside the cold finger are started. The pulse time t1=0.5-3s, and the intermittent time t2=2-8s.

[0069] The initial feeding temperature of the crystallization stage of this group is 110℃, and it is kept for one hour to completely melt. The initial crystallization temperature is set to 84℃, and then it is continuously cooled to 81.5℃. The crystallization stage lasts for 9 hours, and the mother liquor is discharged. The setting temperature of the sweating stage is 89.5℃, and the duration is 3h. The setting temperature of the melting stage is 110.0℃, and the duration is 1h.

[0070] The data summary is shown in Table 1, and the crystallization state after 1h is shown in Figure 7 It can be seen from the figure that the crystal growth state is obviously better than Figure 5 , Figure 6 .

[0071] Table 1: Data of three groups of comparative experiments of material A

[0072] Reference Figures 5 to 10And combined with the data in Table 1, by comparing the second group (cold finger only) in the comparative experiment with the first group (traditional), the yield, purity, time is slightly improved, which proves that the cold finger strengthens the heat transfer, but the improvement is limited, because it does not solve the root problem. The third group (cold finger-ultrasonic) compared with the previous two groups, the yield (50.92%) and time (14h) are significantly optimized, which proves that the synergistic effect brought by "ultrasonic-cold finger coupling" is huge, and the yield, time, purity are improved. In terms of the three groups of comparative experiment data of material A, under the condition of obtaining similar product content (>99%), the yield comparison is: plate type melt crystallizer < plate type melt crystallizer + cold finger device < plate type melt crystallizer + cold finger device + ultrasonic device, the higher the yield, the more product obtained. Batch time comparison: plate type melt crystallizer > plate type melt crystallizer + cold finger device > plate type melt crystallizer + cold finger device + ultrasonic device; the shorter the batch time, the greater the processing capacity of a single machine, and the lower the investment cost.

[0073] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, should be within the protection scope of the present application.

Claims

1. An ultrasonic-cold finger coupling plate melt crystallizer (1), characterized in that, include: The crystallizer body (2) extends along the first direction and is composed of multiple parallel heat exchange plates inside, each of which has a built-in serpentine refrigerant channel. Multiple ultrasonic vibrating plates (40) are arranged sequentially around the shell plate of the plate-type melting crystallizer (1) to provide an ultrasonic field covering the entire crystallizer body (2); At least one cold finger assembly is located on top of the plate melt crystallizer (1) and is connected to the upper cover plate of the crystallizer body (2) via a detachable flange; The cold finger assembly includes an inlet manifold (30), an outlet manifold (31), a cold finger body (32), and an ultrasonic probe (33); the inlet manifold (30) and the outlet manifold (31) are arranged parallel to each other above the crystallizer body (2) along the second direction; The bottom of each of the cold finger bodies (32) is located inside the crystallizer body (2), and the two ends of the top are respectively connected to the inlet manifold (30) and the outlet manifold (31); the ultrasonic probe (33) extends along a third direction and is inserted into the interior of the cold finger body (32); An external junction box (4) is used to connect to and control the ultrasonic probe (33) and multiple ultrasonic vibrating pads (40).

2. The plate-type melt crystallizer (1) according to claim 1, characterized in that, The acoustic intensity of the ultrasonic vibrating plate (40) is 0.1-0.5 W·cm. -2 The frequency is 20~50kHz; the frequency of the ultrasonic probe (33) is 20~50kHz.

3. The plate-type melt crystallizer (1) according to claim 1, characterized in that, The cold finger body (32) includes an inlet section (34), a U-shaped section (35), an outlet section (36), and a quick-connect clamp (38). The inlet section (34) and the outlet section (36) are respectively located on both sides of the top of the U-shaped section (35) along the first direction and are smoothly connected to the U-shaped section (35). The end of the inlet section (34) away from the U-shaped section (35) is connected to the inlet manifold (30), and the end of the outlet section (36) away from the U-shaped section (35) is connected to the outlet manifold (31). The quick-connect clamp (38) is respectively located at the end of the inlet section (34) near the inlet manifold (30) and the end of the outlet section (36) near the outlet manifold (31).

4. The plate-type melt crystallizer (1) according to claim 3, characterized in that, The ultrasonic probe (33) is correspondingly disposed within the U-shaped segment (35) with an insertion depth of 80-120 mm, and the diameter of the ultrasonic probe (33) is 1-2 mm smaller than the diameter of the U-shaped segment (35).

5. The plate-type melt crystallizer (1) according to claim 1, characterized in that, The cold finger assembly also includes a temperature sensor (37), which is inserted into the outlet manifold (31) and the insertion depth corresponds to the center position of the outlet manifold (31) for real-time monitoring of the outlet temperature of the cold finger assembly.

6. The plate-type melt crystallizer (1) according to any one of claims 1-5, characterized in that, The ultrasonic probe (33) and ultrasonic vibrating plate operate in pulse-intermittent mode, with pulse time t1=0.5~3s and interval time t2=2-8s, generating micro-vibrations with amplitude of 10-50μm on the surface of the cold finger.

7. A continuous purification process applied to the ultrasonic-cold finger coupling plate melt crystallizer (1) according to any one of claims 1 to 6, characterized in that, Includes the following steps: Pre-cooling-ultrasonic pre-nucleation stage: cooling refers to the body (32) being cooled to Tc=Tf-(8~12)℃, while ultrasound is performed at 20kHz and 0.3-0.5W·cm. -2 Continuous ultrasonic treatment generates microcrystal nuclei inside the melt, where Tc is the cold finger temperature and Tf is the melt crystallization temperature; Rapid crystal growth stage: turn off the ultrasound, and continue to cool the cold finger component to Tc=Tf-(15~18)℃, forming a 0.5~1mm crystal layer; Ultrasonic-cold finger resonance crystal fragmentation and regeneration stage: The ultrasonic wave is restarted and the ultrasonic frequency is adjusted to match the inherent frequency of the cold finger body (32). The surface of the cold finger body (32) vibrates slightly, causing the crystal layer to break and regenerate. Sweating-ultrasound combined impurity removal stage: Stop ultrasound, raise the temperature to Tc=Tf-(2~4)℃ at 0.5℃ / min, turn on ultrasound for 1 second every 30 seconds, pulse intensity 2W·cm -2 The mother liquor enriched on the surface of the crystal layer is squeezed out; Final melting-collection stage: Heat to Tf+2℃, melt the crystal layer and collect the product.

8. The continuous purification process according to claim 7, characterized in that, The process of restarting the ultrasound, adjusting the ultrasound frequency to match the inherent frequency of the cold finger body (32), and causing micro-vibration of the surface of the cold finger body (32) to break and regenerate the crystal layer includes: The ultrasonic probe (33) and ultrasonic vibrating plate operate in pulse-intermittent mode, with pulse time t1=0.5~3s and interval time t2=2-8s. The cold finger surface generates micro-vibrations with an amplitude of 10-50μm, which weakens the van der Waals force between the crystal and the wall. The cavitation jet impacts and shears the loosened crystal layers and dendrites from the sides and inside, forming fragments of 1~50µm. The fragments are instantly captured by the supercooled melt near the surface of the cold finger, becoming new crystal nuclei and continuing to grow.

9. The continuous purification process according to claim 7, characterized in that, To stop the ultrasound, the temperature is increased to Tc = Tf - (2~4)℃ at a rate of 0.5℃ / min, and the ultrasound is turned on for 1 second every 30 seconds with a pulse intensity of 2W·cm. -2 The process of extruding the mother liquor enriched on the crystal surface includes: The cold finger body (32) slowly heats up, and the intercrystalline impurity mother liquor begins to melt to form a liquid film, but is bound between the crystals by capillary force; Every 30 seconds, the ultrasonic system independently emits a 1-second high-intensity pulse that impacts the entire crystal layer, squeezing out or shaking out the impurity liquid film between the crystal gaps and discharging it into the main body of the mother liquor.

10. The continuous purification process according to claim 7, characterized in that, The pre-cooling-ultrasonic pre-nucleation stage, the rapid crystal growth stage, the ultrasonic-cold finger resonance crystal fragmentation and regeneration stage, the sweating-ultrasonic synergistic impurity removal stage, and the final melting-collection stage are all in continuous operation mode. The total working time includes: the processing time of the pre-cooling-ultrasonic pre-nucleation stage is 0-30s, the processing time of the rapid crystal growth stage is 30s-5min, the processing time of the ultrasonic-cold finger resonance crystal fragmentation and regeneration stage is 5-15min, the processing time of the sweating-ultrasonic synergistic impurity removal stage is 15-20min, and the processing time of the final melting-collection stage is 15-20min.

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