An ultrasonic-cold finger coupled plate melt crystallizer and continuous purification process

Abstract

This invention discloses an ultrasonic-cold finger coupled plate melt crystallizer and a continuous purification process. The crystallizer body includes multiple heat exchange plates, each with a built-in serpentine refrigerant channel; multiple ultrasonic vibrating plates are sequentially arranged around the shell of the plate melt crystallizer to provide an ultrasonic field covering the entire crystallizer body; at least one cold finger assembly is located on top of the plate melt crystallizer and connected to the upper cover plate of the crystallizer body via a detachable flange. The cold finger assembly includes an inlet manifold, an outlet manifold, a cold finger body, and an ultrasonic probe. The inlet and outlet manifolds are arranged parallel to each other above the crystallizer body along a second direction. The bottom of each cold finger body is located within the crystallizer body, and its top two ends are connected to the inlet and outlet manifolds, respectively. The ultrasonic probe extends along a third direction and is inserted into the interior of the cold finger body. Using the melt crystallizer and process of this invention enables higher crystallization efficiency and greater product yield.

Description

Technical Field

[0001] This invention relates to the field of melt crystallization separation and purification equipment, and in particular to an ultrasonic-cold finger coupling plate melt crystallizer and a continuous purification process. Background Technology

[0002] While existing ultrasonic technology is widely used in solution crystallization, it faces several challenges in molten crystallization: First, although existing cold finger technology can locally enhance cooling, a thick crystalline layer easily forms on the surface of the cold finger, rapidly increasing thermal resistance. Furthermore, the high adhesion between the crystal and the cold finger wall makes peeling difficult. Second, the cavitation-microjets of ultrasound during crystallization can promote nucleation and inhibit scaling, but a single ultrasonic transducer experiences rapid energy decay and has a limited effective area, making efficient coupling with plate crystallizers difficult. Summary of the Invention

[0003] This invention provides an ultrasonic-cold finger coupling plate melt crystallizer to solve the problems of rapid energy attenuation, limited effective area, and difficulty in efficient coupling with plate crystallizers caused by single ultrasonic transducers in the prior art.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is to provide an ultrasonic-cold finger coupling plate melt crystallizer, comprising:

[0005] The crystallizer body 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.

[0006] Multiple ultrasonic vibrating plates are sequentially arranged around the shell plate of the plate-type melting crystallizer to provide an ultrasonic field covering the entire crystallizer body.

[0007] At least one cold finger assembly is located on top of the plate melt crystallizer and is connected to the upper cover plate of the crystallizer body via a detachable flange.

[0008] The cold finger assembly includes an inlet manifold, an outlet manifold, a cold finger body, and an ultrasonic probe. The inlet manifold and the outlet manifold are arranged parallel to each other above the crystallizer body along the second direction.

[0009] The bottom of each cold finger body is located within the crystallizer body, and the two ends of its top are respectively connected to the inlet manifold and the outlet manifold. The ultrasonic probe extends in a third direction and is inserted into the interior of the cold finger body.

[0010] An external junction box is used to connect to and control the ultrasonic probe and multiple ultrasonic vibrating pads.

[0011] The ultrasonic-cold finger coupling plate melt crystallizer provided by the present invention has multiple ultrasonic vibrating plates arranged sequentially around the shell plate of the plate melt crystallizer, which can provide an ultrasonic field covering the entire crystallizer body. The cavitation effect of the ultrasonic waves will generate a local high temperature and high pressure environment in the solution. When the cavitation bubbles collapse, they will generate strong microjets, which can break the static equilibrium of the solution and help solute molecules reach the crystallization interface more quickly, thereby accelerating the crystallization process.

[0012] Preferably, the acoustic intensity of the ultrasonic vibrating plate is 0.1-0.5 W·cm. -2 The frequency of the ultrasonic probe is 20~50kHz.

[0013] Preferably, the cold finger body includes an inlet section, a U-shaped section, an outlet section, and quick-connect clamps. The inlet section and the outlet section are respectively located on both sides of the top of the U-shaped section along the first direction and are smoothly connected to the U-shaped section. The end of the inlet section away from the U-shaped section is connected to the inlet manifold, and the end of the outlet section away from the U-shaped section is connected to the outlet manifold. The quick-connect clamps are respectively located at the end of the inlet section near the inlet manifold and the end of the outlet section near the outlet manifold.

[0014] Preferably, the ultrasonic probe is disposed within the U-shaped segment with an insertion depth of 80-120 mm, and the diameter of the ultrasonic probe is 1-2 mm smaller than the diameter of the U-shaped segment.

[0015] Preferably, the cold finger assembly further includes a temperature sensor, which is inserted into the outlet manifold and the insertion depth corresponds to the center position of the outlet manifold, for real-time monitoring of the outlet temperature of the cold finger assembly.

[0016] Preferably, the ultrasonic probe and ultrasonic vibrating plate operate in a pulse-intermittent mode, with a pulse time t1 = 0.5~3s and an interval time t2 = 2-8s, generating micro-vibrations with an amplitude of 10-50μm on the surface of the cold finger. Therefore, under the combined action of the ultrasonic probe and ultrasonic vibrating plate located inside and outside the cold finger, the micro-vibrations generated on the surface of the cold finger ensure that the fragments after the crystal layer breaks are evenly distributed, avoiding excessively dense or sparse local crystal nuclei.

[0017] The technical solution adopted in this invention also includes a continuous purification process applied to the ultrasonic-cold finger coupling plate melt crystallizer described in the above-mentioned embodiments, comprising the following steps:

[0018] Pre-cooling-ultrasonic pre-nucleation stage: Cooling refers to cooling the bulk material to Tc=Tf-(8~12)℃, while simultaneously using ultrasound at 20kHz and 0.3-0.5W·cm. -2Continuous action generates microcrystal nuclei inside the melt, where Tc is the cold finger temperature and Tf is the melt crystallization temperature.

[0019] Rapid crystal growth stage: Turn off the ultrasound and continue to cool the cold finger component to Tc=Tf-(15~18)℃, and form a 0.5~1mm crystal layer.

[0020] Ultrasonic-cold finger resonance crystal fragmentation and regeneration stage: The ultrasound is restarted, and the ultrasound frequency is adjusted to match the inherent frequency of the cold finger body. The surface of the cold finger body vibrates slightly, causing the crystal layer to break and regenerate.

[0021] 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.

[0022] Final melting-collection stage: Heat to Tf+2℃, melt the crystal layer and collect the product.

[0023] Compared to existing technologies, the ultrasonic-cold finger coupled plate melt crystallizer provided by this invention has the following beneficial effects through the synergy of cold finger and ultrasonic technology:

[0024] Introducing high-frequency micro-vibrations in the early stages of crystal layer formation reduces the adhesion force between the crystal and the wall, suppresses excessive crystal growth online, and maintains the thin crystal layer.

[0025] By using ultrasonic cavitation to peel off microcrystals, a thin crystalline layer on the surface of the cold finger is maintained, and crystal scars are continuously peeled off without the need for mechanical scraping, thus continuously enhancing heat transfer.

[0026] Precise control of crystal size and morphology can be achieved through adjustable ultrasonic fields, thereby improving product purity and yield.

[0027] Furthermore, the step of restarting the ultrasound, adjusting the ultrasound frequency to match the inherent frequency of the cold finger body, and causing micro-vibration on the surface of the cold finger body to break and regenerate the crystal layer includes:

[0028] The ultrasonic probe and ultrasonic vibrating plate operate in a pulse-intermittent mode, with a pulse time t1 = 0.5~3s and an interval time t2 = 2-8s. The cold finger surface generates micro-vibrations with an amplitude of 10~50μm, which weakens the van der Waals forces between the crystal and the wall.

[0029] The cavitation jet impacts and shears the loosened crystal layers and dendrites from the sides and inside, forming fragments of 1~50µm.

[0030] The fragments are instantly captured by the supercooled melt near the surface of the cold finger, becoming new crystal nuclei and continuing to grow.

[0031] Furthermore, the ultrasound is stopped, and the temperature is increased to Tc = Tf - (2~4)℃ at a rate of 0.5℃ / min. The ultrasound is then 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:

[0032] As the cold finger body slowly heats up, the intercrystalline impurities begin to melt and form a liquid film, but are bound between the crystals by capillary forces.

[0033] 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.

[0034] Furthermore, 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. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0036] Figure 1 This is a perspective view of an ultrasonic-cold finger coupling plate melt crystallizer provided by the present invention;

[0037] Figure 2 This is a schematic diagram of the cold finger assembly in an ultrasonic-cold finger coupled plate melt crystallizer provided by the present invention;

[0038] 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;

[0039] Figure 4 This is a partial structural schematic diagram of an ultrasonic-cold finger coupling plate melt crystallizer provided by the present invention;

[0040] Figure 5This is a diagram of the initial 1-hour crystallization state of material A using the conventional plate melt crystallization method (Method 1).

[0041] 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;

[0042] Figure 7 This is a diagram of the initial 1-hour crystallization state of material A using the three-cold finger-ultrasonic crystallization method;

[0043] Figure 8 for Figure 5 Chromatogram of the finished product corresponding to the intermediate crystallization state;

[0044] Figure 9 for Figure 6 Chromatogram of the finished product corresponding to the intermediate crystallization state;

[0045] Figure 10 for Figure 7 Chromatogram of the finished product corresponding to the intermediate crystallization state. Detailed Implementation

[0046] 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.

[0047] 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;

[0048] 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.

[0049] 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:

[0050] 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.

[0051] 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.

[0052] At least one cold finger assembly is located on top of the plate-type melt crystallizer 1 and connected to the upper cover plate of the crystallizer body 2 via a detachable flange. In this embodiment, the top of the crystallizer body 2 is provided with two sets of cold finger assemblies (A / B). The two sets of cold finger assemblies serve as backups for each other. After cold finger assembly A has been used for multiple batches, cold finger assembly B is switched on, and cold finger assembly A is lifted out as a whole for cleaning. This allows the cold finger assemblies to be switched during the feeding process and lifted out for cleaning as a whole, thereby improving the working efficiency of the melt crystallizer 1.

[0053] 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 aligned along a second direction (…). Figure 1 (As shown in the Y direction) is positioned parallel to the top of the crystallizer body 2.

[0054] The bottom of each cold finger body 32 is located inside the crystallizer body 2, and its two ends at the top are connected to the inlet manifold 30 and the outlet manifold 31, respectively. The ultrasonic probe 33 travels along a third direction ( Figure 1 Extending in the Z direction (as shown), and inserted into the interior of the cold finger body 32, the first direction (X), the second direction (Y) and the third direction (Z) in this application are perpendicular to each other.

[0055] External junction box 4 connects to and controls ultrasonic probe 33 and multiple ultrasonic vibrating pads 40.

[0056] The ultrasonic-cold finger coupled plate melt crystallizer 1 provided in this application has multiple ultrasonic vibrating plates 40 sequentially arranged around the shell plate of the plate melt crystallizer 1, which can provide an ultrasonic field covering the entire crystallizer body 2. The cavitation effect of ultrasound will create a local high temperature and high pressure environment in the solution. When the cavitation bubbles collapse, a strong micro-jet will be generated, which can break the static equilibrium of the solution and help solute molecules reach the crystallization interface more quickly, thereby accelerating the crystallization process. An external junction box 4 is uniformly connected to and controls the ultrasonic probe 33 and multiple ultrasonic vibrating plates 40. This integrated control method can achieve precise adjustment of ultrasonic energy. The operator can flexibly adjust the vibration frequency and amplitude of the ultrasonic vibrating plates 40, as well as the power of the ultrasonic probe 33, according to different crystallization materials and process requirements through the external junction box 4. The cold finger body 32 can guide the crystallization direction, so that the crystal grows in a certain direction around the cold finger, thereby obtaining a regular crystal shape.

[0057] In some embodiments, 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.

[0058] For example, the sound intensity range is set to 0.1-0.5 W·cm. -2 This provides sufficient energy to promote the crystallization process while avoiding the potential for solute decomposition or crystallizer damage due to excessively high sound intensity. The frequency range of 20~50kHz is the optimal frequency range for ultrasound to propagate in liquids and generate cavitation effects. It can produce strong microjets and local high-temperature and high-pressure environments, which helps solute molecules reach the crystallization interface more quickly.

[0059] In some embodiments, reference Figures 1 to 4 The cold finger body 32 includes an inlet section 34, a U-shaped section 35, an outlet section 36, and quick-connect clamps 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 a 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. Quick-connect clamps 38 are 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.

[0060] For example, the inlet section 34 and the outlet section 36 are respectively located on the top two sides of the U-shaped section 35. This arrangement allows the refrigerant to be evenly distributed throughout the U-shaped section 35. After entering the U-shaped section 35 from the inlet section 34, the refrigerant flows along the inner wall of the U-shaped section 35, ensuring full contact with the heat source inside the crystallizer. Quick-connect clamps 38 are respectively located at the end of the inlet section 34 near the inlet manifold 30 and at the end of the outlet section 36 near the outlet manifold 31. This quick-connect clamp design makes the installation and removal of the cold finger body 32 more convenient and quick.

[0061] In some embodiments, reference Figures 1 to 4 The ultrasonic probe 33 is positioned within the U-shaped section 35, with an insertion depth of 80~120mm. The diameter of the ultrasonic probe 33 is 1~2mm smaller than the diameter of the U-shaped section 35. This ensures that the installation of the ultrasonic probe 33 does not interfere with the process. However, a gap greater than 3mm cannot guarantee the ultrasonic effect.

[0062] For example, the ultrasonic probe 33 is inserted into the U-shaped segment 35 to a depth of 80~120mm. This depth range can ensure that the ultrasonic energy can be accurately applied to the crystallization region inside the U-shaped segment 35, promoting the movement of solute molecules and the crystallization process.

[0063] In some embodiments, reference Figures 1 to 4 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.

[0064] For example, by installing a temperature sensor 37 inside the outlet manifold 31, temperature changes during the crystallization process can be monitored in real time, thereby enabling more precise control of the crystallization process. The insertion depth of the temperature sensor 37 corresponds to the center position of the outlet manifold 31. This design ensures that the temperature measured by the sensor more accurately reflects the actual outlet temperature of the cold finger assembly. The temperature sensor 37, ultrasonic probe 33, and ultrasonic vibrator 40 are all explosion-proof, with an explosion-proof rating of Exd-IIB-T4.

[0065] The technical solution provided in this application also includes a continuous purification process applied to the ultrasonic-cold finger coupling plate melt crystallizer 1 described in the above embodiments, comprising the following steps:

[0066] Step S01: Pre-cooling - Ultrasonic pre-nucleation stage: Cooling refers to lowering the body temperature to Tc=Tf-(8~12)℃, while simultaneously using ultrasound at 20kHz and 0.3-0.5W·cm. -2 Continuous action generates microcrystal nuclei inside the melt, where Tc is the cold finger temperature and Tf is the melt crystallization temperature.

[0067] For example, this stage utilizes deep supercooling to provide a strong nucleation driving force (ΔG∝ΔT), while simultaneously utilizing ultrasonic cavitation to generate 10 within the melt. 2 -10 3 Microcrystalline nuclei of 1-5µm are generated. The key to this step is pre-nucleation: pre-nucleation prevents subsequent steps from relying on primary nucleation, avoids localized overcooling or overheating leading to mother liquor inclusion, improves final purity, and ensures that subsequent growth no longer depends on random and uncontrollable primary nucleation. This avoids the extreme overcooling conditions set up to induce nucleation, thereby reducing mother liquor inclusion caused by explosive nucleation and rapid growth from the source.

[0068] Step S02: 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.

[0069] For example, with a large number of existing crystal nuclei, the ultrasound is turned off to create a quiet laminar flow growth environment, and the "thin crystal layer - high heat transfer" state is used to leave impurities on the mother liquor side. At this point, due to the large number of crystal nuclei, the space available for growth of each nucleus is limited, thus naturally forming a thin crystal layer. Furthermore, laminar flow is maintained during the growth stage, reducing intergranular entrainment and improving primary purity. Driven by a high temperature gradient (large temperature difference between the two ends of the thin crystal layer), heat is rapidly removed, and the crystals grow quickly but in an orderly manner. The key to this stage is to utilize the pre-nucleation results to achieve controllable rapid growth.

[0070] Step S03: Ultrasonic-Cold Finger Resonance Crystal Fragmentation and Regeneration Stage: Restart the ultrasonic process and adjust the ultrasonic frequency to match the inherent frequency of the cold finger body 32 (usually 20~40kHz). The surface of the cold finger body 32 vibrates slightly, causing the crystal layer to break and regenerate.

[0071] For example, matched-frequency ultrasound induces precise micro-vibrations of 10–50 μm on the surface of the cooled finger. When the amplitude is less than 10 μm, the surface displacement is too small, and the inertial force and shear stress are insufficient to overcome the crystal-wall van der Waals adsorption potential. Conversely, when the amplitude is greater than 50 μm (too long), the surface displacement is too large, causing the crystal to be "shaken off" or slip away from the supercooled region. Simultaneously, energy dissipation increases, leading to a local temperature rise. Furthermore, the enormous shear force of the cavitation microjets directly shatters the grown dendrite arms. The resulting 1–50 μm fragments are instantly captured by the surrounding supercooled melt, becoming new perfect crystal nuclei. This forms a positive feedback loop of fragmentation → providing crystal nuclei → regeneration. The crystal layer formed by the recombination of microcrystals is far denser than the freely grown dendrite layer, with fewer defects and voids, and shorter impurity diffusion paths, laying a solid foundation for subsequent sweating.

[0072] Step S04: Sweating-Ultrasound Combined Impurity Removal Stage: Stop ultrasound, increase the temperature at 0.5℃ / min to Tc=Tf-(2~4)℃, 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.

[0073] For example, the essence of sweating is to slowly heat up the liquid, which is rich in impurities and remains between the crystals, and then discharge it. High-intensity short-pulse ultrasound generates extremely strong instantaneous vibrations, which, like a vibrating screen, effectively overcome capillary forces and squeeze the impurity liquid film out of the crystal layer. This is a mechanically assisted mass transfer process that greatly improves the sweating efficiency and impurity removal effect.

[0074] Step S05: Final melting-collection stage: Heat to Tf+2℃, melt the crystal layer and collect the product.

[0075] For example, this stage is a routine operation, but due to the optimization of the preceding steps, the final yield and purity are significantly improved. By strictly synchronizing the rhythm of the ultrasound "on-off-pulse" with the rhythm of the cold finger "cooling-constant temperature-heating", we can exert force at the two key nodes of "crystal fragmentation and refinement" and "sweating and impurity removal", thereby improving the product purity and yield.

[0076] In some embodiments, reference Figures 1 to 4 Re-activating the ultrasound, adjusting the ultrasound frequency to match the inherent frequency of the cold finger body 32, and causing micro-vibration on the surface of the cold finger body 32 to break and regenerate the crystal layer, including:

[0077] The ultrasonic probe 33 and ultrasonic vibrating plate 40 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 cold finger surface, which weakens the van der Waals force between the crystal and the wall.

[0078] The cavitation jet impacts and shears the loosened crystal layers and dendrites from the sides and inside, forming fragments of 1~50µm.

[0079] The fragments are instantly captured by the supercooled melt near the surface of the cold finger, becoming new crystal nuclei and continuing to grow.

[0080] For example, the micro-vibrations generated on the surface of the cold finger ensure a uniform distribution of fragments after the crystal layer breaks, avoiding excessively dense or sparse local nuclei. This uniform distribution contributes to the uniform growth of subsequent crystal layers, improves crystal quality, and makes the crystal size distribution more uniform. Deep supercooling lowers the thermodynamic energy barrier, and cavitation micro-perturbations provide additional nucleation sites. The combination of these two factors increases the nucleation rate by 2 to 3 orders of magnitude. Meanwhile, the shear force generated by cavitation continuously strips away the primary nuclei, preventing excessive thickness of the crystal layer and maintaining the surface of the cold finger in a thin-layer, high-heat-transfer state. The thinner the crystal layer, the lower the thermal resistance, and the more heat can be transferred per unit time, thus maintaining a higher crystallization rate. This is because thermal resistance is proportional to thickness: the thermal conductivity of the crystal layer itself is much lower than that of the metal wall. Once the thickness increases, the thermal resistance rises rapidly, the heat transfer efficiency decreases, and the temperature gradient becomes larger: the temperature difference between the two ends of the thin crystal layer is large, the heat flux density is high, and heat can be quickly transferred from the melt to the cooling wall. The crystallization rate is controlled by heat transfer: melting and crystallization is a "heat transfer-dominated" process, and heat must be removed in time for the crystal to continue growing. In the thin-layer state, heat transfer is not a bottleneck, and crystallization can proceed rapidly and sustainably. During the secondary nucleation stage, the cavitation jet breaks the already formed dendrites into numerous microcrystalline fragments. These fragments, acting as new crystal nuclei, are recaptured by the cold-finding supercooled layer, achieving "continuous regeneration of crystal nuclei," further refining the grains and reducing the grain size distribution.

[0081] In some embodiments, reference Figures 1 to 4 Stop the ultrasound, increase the temperature at 0.5℃ / min to Tc=Tf-(2~4)℃, and turn on the ultrasound 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:

[0082] The cold finger body 32 is slowly heated, and the mother liquor of intercrystalline impurities begins to melt and form a liquid film, but is bound between the crystals by capillary force.

[0083] 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.

[0084] For example, periodic ultrasonic pulses can effectively break the capillary force, squeezing or shaking out the impurity liquid film from the crystal layer, thus improving the impurity removal efficiency. At the same time, 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 undertreatment or overtreatment, and improve the uniformity and consistency of impurity removal.

[0085] In some embodiments, reference Figures 1 to 4The 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.

[0086] For example, 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 continuous working modes, with seamless connection between each stage, reducing operation downtime and improving overall production efficiency.

[0087] Further reference Figures 5 to 10 Three sets of comparative experiments were conducted using material A to test the conventional plate melt crystallization process, crystallization using a cold indexing device alone, and cold indexing-ultrasonic crystallization process:

[0088] The first group used a conventional plate melt crystallization process, controlling the temperature within the plate to crystallize, sweat, and melt, thus purifying the material. The initial feed was 6.53 kg, the crude raw material content was 93.10%, the batch time was 20 hours, the crystallization time was 12 hours, the yield was 45.48%, and the finished product content was 99.11% (see [link to relevant documentation]). Figure 8 ).

[0089] The initial feed temperature for the crystallization stage was 110℃, maintained for one hour until complete melting. The initial crystallization temperature was set at 84℃, then lowered to 82℃ after crystal formation, and the crystallization stage lasted 12 hours. The sweating stage was set at 91.5℃ for 6 hours, and the melting stage was set at 110.0℃ for 1 hour. Data summary is shown in Table 1, and the crystallization status after 1 hour is shown in [Table 1]. Figure 5 .

[0090] The second group started the plate-type melt crystallization cold fingering device. The initial feed was 6.14 kg, the finished product was 2.91 kg, the yield was 47.39%, and the finished product content was 99.36% (see [link]). Figure 9 The batch time is 17 hours, the crystallization time is 11 hours, and the set temperature of the cold indexing device is 5℃ lower than the material's crystallization temperature T-5℃ (T is the material's crystallization temperature). A supercooled zone is formed in the area of ​​the cold indexing device. The crystallization state can be observed after 1 hour of crystallization. Figure 6 It is evident that the crystallization state is superior to that without the use of the cold finger device.

[0091] The initial feed temperature for the crystallization stage was 110℃, maintained for one hour until complete melting. The initial crystallization temperature was then set at 85℃, continuously decreasing to 84℃. After crystal formation, the temperature was further reduced to 82℃, and the crystallization stage lasted 11 hours. During the mother liquor discharge process, the temperature was raised to 84℃. The sweating stage was set at 91.5℃ for 4 hours, and the melting stage was set at 110.0℃ for 1 hour. Data summary is shown in Table 1, and the crystallization status after 1 hour is shown in [Table 1]. Figure 6 .

[0092] The third group, using a cold indexing method, had an initial feed of 4.91 kg, a finished product of 2.5 kg, a yield of 50.92%, and a finished product purity of 99.25% (see [reference]). Figure 10 The batch time is 14 hours, the crystallization time is 9 hours, the cold finger temperature is set to T-5℃, and the ultrasonic vibration plates 40 around the crystallizer and the ultrasonic probe 33 inside the cold finger are started at the same time. The pulse time t1=0.5-3s and the interval time t2=2-8s.

[0093] The initial feed temperature for the crystallization stage was 110℃, maintained for one hour until complete melting. The initial crystallization temperature was set at 84℃, and after crystals appeared, the temperature was lowered to 81.5℃. The crystallization stage lasted for 9 hours, after which the mother liquor was drained. The temperature for the sweating stage was set at 89.5℃, and the duration was 3 hours. The temperature for the melting stage was set at 110.0℃, and the duration was 1 hour.

[0094] The data summary is shown in Table 1, and the crystallization status after 1 hour is shown in Table 1. Figure 7 As can be seen from the figure, the crystal growth state is significantly better than that of the others. Figure 5 , Figure 6 The state.

[0095] Table 1: Comparative Experimental Data of Material A in Three Groups

[0096] refer to Figures 5 to 10 Based on the data in Table 1, it can be seen that compared with the first group (traditional), the second group (cold indexing only) showed slight improvements in yield, purity, and time, proving that cold indexing enhances heat transfer, but the improvement is limited because it does not solve the fundamental problem. Compared with the first two groups, the third group (cold indexing-ultrasonic) showed significant optimization in yield (50.92%) and time (14h), proving that the synergistic effect brought by "ultrasonic-cold indexing coupling" is huge, with improvements in yield, time, and purity. Considering the three sets of comparative experimental data for material A, under the condition of achieving similar product content (>99%), the yield comparison is: plate melt crystallizer < plate melt crystallizer + cold indexing device < plate melt crystallizer + cold indexing device + ultrasonic device. The higher the yield, the greater the amount of product obtained.

[0097] Batch time comparison: Plate melt crystallizer > Plate melt crystallizer + cold fingering device > Plate melt crystallizer + cold fingering device + ultrasonic device; The shorter the batch time, the greater the single unit processing capacity and the lower the investment cost.

[0098] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, should be included within the protection scope of the present invention.

Claims

1. An ultrasonic-cold finger coupled plate-type melt crystallizer (1), characterized in that, The application relates to a plate-type melt crystallizer (1) and a cooling finger assembly thereof. The plate-type melt crystallizer (1) comprises a crystallizer body (2) extending along a first direction and internally composed of a plurality of parallel heat exchange plates, each of which is internally provided with a serpentine coolant channel; a plurality of ultrasonic vibration pieces (40) arranged around the shell plate of the plate-type melt crystallizer (1) in sequence and used for providing an ultrasonic field covering the whole crystallizer body (2); and at least one cooling finger assembly arranged at the top of the plate-type melt crystallizer (1) and connected with the upper cover plate of the crystallizer body (2) through a detachable flange. The cooling finger assembly comprises an inlet header (30), an outlet header (31), a cooling 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; The bottom of each cooling finger body (32) is arranged in the crystallizer body (2), and the top of each cooling finger body (32) is in communication with the inlet header (30) and the outlet header (31) respectively; The cooling finger body (32) comprises an inlet section (34), a U-shaped section (35) and an outlet section (36); the inlet section (34) and the outlet section (36) are arranged on the two sides of the top of the U-shaped section (35) along the first direction and are both 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 ultrasonic probe (33) extends along a third direction and is arranged in the cooling finger body (32); An external terminal box (4) is arranged for uniformly accessing and controlling the ultrasonic probe (33) and the plurality of ultrasonic vibration pieces (40). The cooling finger body (32) further comprises a quick-connection clamp (38) 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). The ultrasonic probe (33) is arranged in the U-shaped section (35) in correspondence and has an insertion depth of 80-120 mm, and the passage diameter of the ultrasonic probe (33) is 1-2 mm smaller than the passage diameter of the U-shaped section (35).

2. The panel-type melt crystallizer (1) according to claim 1, characterized in that The sound intensity of the ultrasonic vibration piece (40) is 0.1-0.5 W·cm -2 , and the frequency is 20-50 kHz; the frequency of the ultrasonic probe (33) is 20-50 kHz.

3. The panel-type melt crystallizer (1) according to claim 1, characterized in that The cooling finger assembly further comprises a temperature sensor (37) arranged in the outlet header (31) and having an insertion depth corresponding to the central position of the outlet header (31) and used for monitoring the outlet temperature of the cooling finger assembly in real time.

4. The panel-type melt crystallizer (1) according to claim 3, characterized in that The ultrasonic probe (33) and the ultrasonic vibration piece 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 mu m is generated on the surface of the cooling finger.

5. The panel-type melt crystallizer (1) according to claim 1, characterized in that The application further discloses a method for controlling the plate-type melt crystallizer (1).

6. The panel-type melt crystallizer (1) according to any one of claims 1 to 5, characterized in that The method comprises the following steps:

7. A continuous purification process applied to the ultrasonic-cold finger coupled panel-type melt crystallizer (1) according to any one of claims 1 to 6, characterized in that, A crystal layer rapid growth stage: the ultrasonic is turned off, the cooling finger body is continuously cooled to Tc=Tf-(15-18) DEG C, and a 0.5-1 mm crystal layer is formed. Pre-cooling-ultrasonic pre-nucleation stage: the cold finger (32) is cooled to Tc=Tf-(8~12) °C, while the ultrasonic wave is at 20 kHz, 0.3-0.5 W·cm -2 Continuous ultrasonic action, microcrystalline nuclei are generated inside the melt, wherein Tc is the temperature of the cold finger, and Tf is the crystallization temperature of the melt; ​ Ultrasonic-cold finger resonance crystal fragmentation and regeneration stage: the ultrasonic of the ultrasonic probe (33) and the ultrasonic vibration piece (40) is restarted, the ultrasonic frequency is adjusted to match the natural frequency of the cold finger body (32), the cold finger body (32) surface vibrates slightly and makes the crystal layer broken and regenerated; Sweating-ultrasonic synergistic impurity removal stage: stop the ultrasonic probe (33) and the ultrasonic vibration piece (40), and increase the temperature to Tc=Tf-(2~4) °C at a rate of 0.5 °C / min, open the ultrasonic for 1 s every 30 s, and the pulse intensity is 2 W·cm -2 The mother liquor enriched on the surface of the crystal layer is squeezed out; Final melting-collection stage: heating to Tf+2℃, melting the crystal layer and collecting the product.

8. The continuous purification process according to claim 7, characterized in that, The restarting of the ultrasonic, the adjustment of the ultrasonic frequency to match the natural frequency of the cold finger body (32), and the slight vibration of the cold finger body (32) surface to break and regenerate the crystal layer include: The ultrasonic probe (33) and the ultrasonic vibration piece operate in pulse-intermittent mode, the pulse time t1=0.5~3s, the intermittent time t2=2-8s, the cold finger surface generates micro-vibration with an amplitude of 10-50μm, and the van der Waals force between the crystal and the wall surface is weakened; The cavitation jet impacts and shears the loosened crystal layer and dendrite from the side and inside, forming 1~50µm fragments; The fragments are instantly captured by the supercooled melt near the cold finger surface to become new crystal nuclei and continue to grow.

9. The continuous purification process of claim 7, wherein, The ultrasonic is stopped, and the temperature is increased to Tc=Tf-(2~4) °C at a rate of 0.5 °C / min, the ultrasonic is started for 1 second every 30 seconds, and the pulse intensity is 2 W·cm -2 Extruding the mother liquor enriched on the surface of the crystal layer comprises: The cold finger body (32) is slowly heated, and the intergranular 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 and hits the entire crystal layer, extruding 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 of claim 7, wherein, The pre-cooling-ultrasonic pre-nucleation stage, the crystal layer rapid growth stage, the ultrasonic-cold finger resonance crystal fragmentation and regeneration stage, the sweating-ultrasonic cooperative impurity removal stage and the final melting-collection stage are in 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 fragmentation and regeneration stage is 5-15min, the processing time of the sweating-ultrasonic cooperative impurity removal stage is 15-20min, and the processing time of the final melting-collection stage is 15-20min.

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