A device for solution crystallization purification and a control method thereof

Abstract

The scheme discloses a device for solution crystallization purification, comprising a container, two TEC modules respectively located at the upper and lower parts of the container, and a TEC module comprising a TEC; the height of the refrigeration end of the upper TEC module is adjustable to be in contact with the liquid level in the container. The TEC module further comprises a passive natural radiator arranged at the heat dissipation end. A vertical guide rail is further included, and the upper TEC module is connected to the guide rail and can slide up and down. The refrigeration end of the TEC module is made of metal. The refrigeration end of the upper TEC module is coated with a protective layer. Temperature sensors are further included on the two TEC modules. A control assembly is further included, which comprises a controller and a TEC driving module; the temperature sensors are signal-connected with the controller, and the TEC modules are signal-connected with the TEC driving module. The scheme further discloses a control method of the device. The beneficial effects of the scheme are as follows: the temperature gradient is stable and controllable; there is no vibration and no leakage; the material compatibility is good; flexibility and stability are combined; and the structure is simple and easy to operate.

Description

Technical Field

[0001] This invention relates to the field of solution crystallization technology, specifically a static gradient crystallization device and its control method based on a dual TEC (thermal refrigeration unit) module. This device and method are suitable for laboratory-scale crystallization experiments that are sensitive to vibrations in the crystallization environment and require precise temperature gradient control, such as biomolecule crystallization, optical crystal growth, and purification crystallization of pharmaceutical intermediates. Background Technology

[0002] Solution crystallization is a key technology for separating, purifying, and preparing crystals in chemical, pharmaceutical, and materials fields. Its core lies in establishing a stable temperature gradient to induce the directional precipitation of solutes in the solution and the formation of high-quality crystals. Chinese patent document CN115300930A, published on November 8, 2022, discloses a rapid crystallization device and process for acetoacetanilide, comprising: a shell with several circumferentially oriented air grooves connected to its inner cavity at the top of the outer wall; an aluminum plate disposed at the top of the shell; a semiconductor cooling chip disposed at the center of the top of the aluminum plate; an epoxy resin with a through-hole mounting groove at the center of its top, the epoxy resin being disposed at the top of the aluminum plate, and the semiconductor cooling chip being fitted and inserted into the inner cavity of the mounting groove; and a heat sink embedded in the top of the inner cavity of the mounting groove. Such traditional crystallization devices mainly suffer from the following problems: 1. Poor temperature gradient stability: Most devices rely on a single cooling / heating element, making it difficult to form a continuous and controllable vertical temperature gradient, resulting in disordered crystal growth direction and low crystallization efficiency. 2. Significant vibration interference: Traditional devices often use fans for heat dissipation. The mechanical vibration generated by the operation of the fans can damage the crystal growth interface, especially for sensitive samples such as biomacromolecules, which can easily lead to crystal defects or even growth failure. 3. Insufficient material compatibility: Some devices use metal surfaces that come into contact with the solution, which may react chemically with the solution, or the crystallization process may not be observed in real time due to poor transparency. 4. Low flexibility: The temperature gradient parameters are fixed, making it impossible to adjust the gradient distribution according to different solution characteristics, thus limiting its applicability. To address the above issues, this invention proposes a static gradient crystallization device and method based on a dual-TEC module. Through coordinated temperature control by the dual-TEC module, natural heat dissipation, a fanless design, and a highly adjustable structure, static crystallization under a low-vibration, highly stable temperature gradient is achieved, improving crystallization quality and experimental flexibility. Summary of the Invention

[0003] In view of the above problems, the present invention provides a device for solution crystallization purification that is easy to manufacture and use and has low cost, and on this basis, provides a control method for the device.

[0004] To achieve the first objective of the invention, the present invention adopts the following technical solution: an apparatus for solution crystallization and purification, comprising: container; Two TEC modules are located at the top and bottom of the container, respectively; The TEC module includes the TEC and a passive natural heat sink located at the heat dissipation end of the TEC; The lifting mechanism allows for adjustment of the height of the upper TEC module, ensuring that the cooling end of the upper TEC module contacts the liquid surface inside the container.

[0005] Preferably, the passive natural radiator has metal heat dissipation fins for heat exchange with the air.

[0006] Preferably, it also includes a vertical guide rail, on which the upper TEC module is connected and can slide up and down.

[0007] Preferably, the cooling end of the TEC module is made of metal.

[0008] Preferably, the cooling end of the upper TEC module is covered with a protective layer.

[0009] Preferably, temperature sensors are also included, each located on one of the two TEC modules.

[0010] Preferably, the system also includes a control component, which comprises a controller and a TEC drive module; the temperature sensor is signal-connected to the controller, and the TEC module is signal-connected to the TEC drive module.

[0011] Preferably, the sidewalls of the container are transparent and visible.

[0012] Preferably, a thermal pad is provided between the cooling end of the lower TEC module and the bottom of the container.

[0013] Preferably, the metal heat sink fins are made of copper.

[0014] Preferably, the metal heat sink fins are cylindrical in shape.

[0015] Preferably, the cooling end of the TEC is made of copper.

[0016] Preferably, the protective layer covering the cooling end of the upper TEC module is a Teflon coating.

[0017] Preferably, the guide rail is equipped with a slider that can slide along the guide rail, and the slider is equipped with a locking knob; the upper TEC module is fixed to the slider.

[0018] Preferably, the control components also include a touch screen for implementing electrical control of the device.

[0019] Preferably, the container is a glass beaker.

[0020] To achieve the second objective of the invention, the present invention adopts the following technical solution: A method for controlling an apparatus for solution crystallization purification includes the following steps: The first step is to place the liquid to be crystallized into a container; The second step is to place a TEC module at the top of the container in a height-adjustable manner, so that its position is lowered until the cooling end contacts the liquid surface inside the container. The third step is to place another TEC module tightly against the bottom of the container; The fourth step is to connect the two TEC modules to the control component via signal connection. Fifth step, set the target temperature T1 for the upper TEC module and the target temperature T2 for the lower TEC module; where T1 is higher than T2, forming a vertical temperature gradient from the upper surface of the solution to the bottom. Step 6: Start the upper and lower TEC modules. The controller automatically adjusts the TEC drive current based on the temperature sensor feedback data to stabilize the temperature of the upper TEC module to T1 and the temperature of the lower TEC module to T2. The heat from the TEC modules is continuously removed by natural convection through the heat sink to maintain a long-term stable temperature gradient. Step 7: Under a stable temperature gradient, the solute in the solution precipitates out directionally from bottom to top, initiating the static crystallization process; Step 8: After the preset heat preservation time is reached, turn off the two TEC modules, remove the container, and complete the crystallization operation.

[0021] The beneficial effects of this plan are: 1. Stable and controllable temperature gradient: The dual TEC module controls the high-temperature end and the low-temperature end respectively. Combined with the columnar copper heat sink for efficient natural heat dissipation, a continuous vertical temperature gradient with an accuracy of ±0.1℃ can be formed. The timely heat dissipation ensures long-term temperature stability and meets the crystallization requirements of different solutions. 2. Vibration-free and leak-free: The entire device uses a radiator for natural heat dissipation instead of a fan and water cooling, which eliminates the interference of mechanical vibration on crystal growth and avoids the risk of liquid leakage from the water cooling system. It is especially suitable for the crystallization of samples such as biomacromolecules that are sensitive to vibration and contamination. 3. Excellent material compatibility: The upper working surface adopts a combination of copper-plated Teflon. The copper base ensures thermal conductivity, while the Teflon coating is corrosion-resistant, non-adhesive, and chemically inert. The lower part adopts a combination of copper block and thermal pad, which balances thermal conductivity and contact surface fit. It can be used in various solution systems such as acids, alkalis, and organics, avoiding sample contamination. 4. Combining flexibility and stability: The height of the upper TEC module can be adjusted and locked via the guide rail, allowing for flexible adjustment of the temperature gradient distribution and wide applicability; the heat dissipation and temperature control structure is simplified, resulting in a low failure rate; the control components support parameter customization and data export, facilitating small-scale and repeated experimental optimization and recording. 5. Simple structure and easy operation: It uses ordinary glass beakers as the container, which are low in cost and readily available; the device is easy to assemble and debug, and is suitable for daily laboratory use. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the crystallization apparatus of the present invention; Figure 2 This is a schematic diagram of the bottom TEC module structure; In the diagram: 1. Glass beaker; 2. Upper TEC module; 3. Lower TEC module; 4. Guide rail; 5. Controller; 6. Electrical control box; 7. Thermal pad; 8. Cooling block; 9. Heat sink; 10. Thermal protection switch. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0024] This invention provides an apparatus and its control method for solution crystallization purification, aiming to solve problems such as unstable temperature gradients, mechanical vibration interference, poor material compatibility, and low operational flexibility in existing crystallization technologies. This apparatus is particularly suitable for laboratory settings with stringent crystallization requirements, such as biomolecule crystallization, optical crystal growth, and pharmaceutical intermediate purification. The apparatus structure, assembly process, control method, and experimental results of this invention will be described in detail below through two specific embodiments. Example 1

[0025] This embodiment details the specific structure and preferred assembly method of an apparatus for solution crystallization purification provided by the present invention. Please refer to the appendix. Figure 1 and Figure 2 . Figure 1 A schematic diagram of the overall structure of the static gradient crystallization apparatus of the present invention is shown. Figure 2 This shows the detailed structure of the TEC module located at the bottom of the container.

[0026] The core of the device in this embodiment lies in constructing a stable, controllable, and mechanically vibration-free temperature gradient in the vertical direction using two independent TEC (thermal energy dissipation circuit) modules. To this end, the device mainly includes a glass beaker 1 serving as a crystallization reaction vessel, an upper TEC module 2 and a lower TEC module 3 located at the top and bottom of the glass beaker 1 respectively, a support and adjustment assembly for supporting and adjusting the height of the upper TEC module 2, a passive heat dissipation assembly for providing heat dissipation to the two TEC modules, and a control assembly for precisely controlling the temperature.

[0027] First, a common transparent glass beaker (1) is chosen as the container for holding the solution to be crystallized. Glass has excellent chemical inertness, preventing reactions with most acids, alkalis, and organic solutions, thus ensuring the purity of the crystallization process. Simultaneously, its transparency allows researchers to directly observe the nucleation, growth, and morphological changes of the crystals without interrupting the crystallization process. This is crucial for optimizing experimental parameters and real-time assessment of crystal quality. In this embodiment, a 500mL common glass beaker is preferred; however, it is understood that other sizes of glass containers, such as 100mL or 1000mL, can be selected depending on the actual scale of crystallization required.

[0028] Secondly, the specific composition of the dual TEC temperature control assembly is described in detail. Both the upper TEC module 2 and the lower TEC module 3 use thermoelectric coolers (TECs) as their core components. In this embodiment, a TEC1-12706 thermoelectric cooler is selected, which is stable in performance and easy to drive. However, unlike traditional TEC applications, this device has been specifically designed for the working surface and heat dissipation surface of the TEC.

[0029] The upper TEC module 2 is configured to provide the high-temperature end required for crystallization. The upper TEC module 2 is designed with an adjustable height, allowing the cooling end (i.e., the end facing the solution surface) to directly contact the solution. To achieve this, the cooling end of the upper TEC module 2 is made of metal to ensure excellent thermal conductivity. Specifically, a 5mm thick copper block is fixed on its working surface as a cooling block 8. Copper has extremely high thermal conductivity (approximately 401 W / (m·K)), enabling it to quickly and uniformly transfer the heat generated by the TEC to the solution surface. However, while copper has excellent thermal conductivity, it is chemically reactive, and prolonged direct contact with various solutions may lead to chemical reactions, resulting in solution contamination or copper corrosion. Therefore, this invention carefully coats the outer surface of the cooling end (i.e., the copper block) of the upper TEC module 2 with a protective layer using a plasma spraying process. In this embodiment, this protective layer is a Teflon (polytetrafluoroethylene, PTFE) coating with a thickness between 0.1mm and 0.2mm. Teflon material possesses excellent chemical inertness, being virtually insoluble in any solvent, effectively isolating the copper substrate from the solution and preventing corrosion and contamination. Furthermore, Teflon exhibits superior anti-adhesion properties, reducing non-specific adsorption of crystals on the cooling end surface, allowing the crystallization process to primarily occur within the solution, and facilitating cleaning afterward. Thus, the cooling end of the upper TEC module 2 forms a composite working surface of "copper substrate + Teflon coating," combining the dual advantages of high-efficiency thermal conductivity and excellent chemical compatibility.

[0030] The lower TEC module 3 is configured to provide the low-temperature end required for crystallization. The cooling end of the lower TEC module 3 (i.e., the end facing the bottom of the glass beaker 1) also prioritizes thermal conductivity. A 10mm thick copper block is fixed to its working surface as a cooling block 8. The planar dimensions of this copper block are slightly larger than the dimensions of the TEC module to ensure effective collection and conduction of cold energy. To compensate for any microscopic gaps that may exist between the lower surface of the copper block and the bottom of the glass beaker 1, a thermally conductive pad 7 is also provided between the copper block and the bottom of the glass beaker 1. In this embodiment, the thermally conductive pad 7 is a 2mm thick flexible silicone thermally conductive pad with a thermal conductivity of not less than 8.0 W / (m·K). This thermally conductive pad has good compressibility and conformability, and can tightly fill the air gap between two solid surfaces under slight pressure, greatly reducing contact thermal resistance and ensuring that the cold energy generated by the lower TEC module 3 can be efficiently and uniformly transferred to the bottom of the glass beaker 1, thereby forming a stable low-temperature zone at the bottom of the entire container.

[0031] Next, the vibration-free heat dissipation component of the present invention will be described. When the TEC (Transformer Controller) is operating, its non-working surface (i.e., the side opposite the cooling end) generates a large amount of heat (for the upper TEC module, its non-working surface is the hot end; for the lower TEC module, its non-working surface is also the hot end). If this heat cannot be dissipated in time, the cooling efficiency of the TEC will drop sharply, even leading to device damage. Traditional technologies often use fans for forced air cooling, but the mechanical vibration of the fan can severely interfere with the vibration-sensitive crystallization process. Therefore, the present invention employs passive natural heat sinks on the non-working surfaces of both TEC modules. Specifically, as shown... Figure 2 As shown, a passive natural heatsink 9 is tightly bonded to the non-working surfaces of both the upper TEC module 2 and the lower TEC module 3 using a layer of high-performance thermal grease. This heatsink 9 is designed with hundreds of cylindrical fins and is made of copper. The high thermal conductivity of copper ensures that the heat generated by the TEC is rapidly conducted to the entire heatsink. The cylindrical structure increases the contact area with air, and utilizes the chimney effect to guide cool air in from the bottom of the heatsink, which, after being heated, rises naturally from the top and flows out, forming an efficient natural convection circulation. The entire heat dissipation process requires no moving parts such as fans or pumps, thus completely eliminating the risk of mechanical vibration and liquid leakage, providing an absolutely quiet and undisturbed environment for static cooling.

[0032] To achieve height adjustment of the upper TEC module 2, this invention incorporates a lifting mechanism, specifically a support and adjustment assembly. This assembly includes a metal bracket fixed to the control box 6 and a guide rail 4 laid vertically along the bracket. The upper TEC module 2 is connected to the guide rail 4 via a specially designed slider that slides smoothly up and down along the guide rail 4 and is equipped with a locking knob. During experimental preparation, the experimenter can loosen the locking knob to lower the upper TEC module 2 until its Teflon-coated working surface at the cooling end gently contacts the upper surface of the solution in the glass beaker 1. Then, the locking knob is tightened to lock the upper TEC module 2 in this precise position. This design not only allows the device to adapt to containers with different liquid levels and solutions of varying volumes, but more importantly, it allows the experimenter to fine-tune the immersion depth of the upper TEC module 2 in the liquid according to different solute and solvent characteristics, thereby flexibly adjusting the temperature gradient distribution within the solution and greatly expanding the device's applicability.

[0033] Finally, the core of the entire device's control is the control component. This component is integrated into a square, sealed electrical control box 6, which is fixed to the bottom of a metal bracket, ensuring the compactness and stability of the overall structure. The control component mainly includes a controller 5 (MCU), two high-precision temperature sensors (not shown in the figure), a TEC drive module, and a human-machine interface. The two temperature sensors are embedded in the copper blocks of the upper TEC module 2 and the lower TEC module 3, respectively, for real-time and accurate monitoring of the actual temperature of the working surface. The temperature sensors are connected to the controller 5, transmitting the collected temperature data to the controller 5 in real time. The controller 5, as the control center, has advanced control algorithms (such as PID algorithms) pre-set inside. When the user sets the target temperature T1 of the upper TEC module 2 and the target temperature T2 of the lower TEC module 3 via the touch screen, the controller 5 compares the real-time temperature with the target temperature and, based on the deviation, sends instructions to the TEC drive module to dynamically adjust the magnitude and direction of the drive current supplied to the upper TEC module 2 and the lower TEC module 3. This closed-loop negative feedback control allows the temperatures of the two TEC modules to converge quickly and stably to the preset T1 and T2, respectively, with a control accuracy of ±0.1℃. Furthermore, the control component integrates data logging and export functions, allowing key data such as temperature curves throughout the crystallization process to be exported to an external computer via USB or RS485 interface, facilitating subsequent analysis and experimental report writing. The surface of the electrical control box 6 also features auxiliary heat dissipation holes to ensure that heat generated by the internal electronic components during prolonged operation can be dissipated through natural convection, ensuring the long-term stable operation of the control system.

[0034] The TEC assembly also includes a thermal protection switch 10. As a hardware protection feature within the TEC assembly, its purpose is to cut off the circuit when a fault causes abnormally high temperatures, preventing the fault from escalating or causing serious consequences.

[0035] Through the coordinated operation of the above components, this embodiment constructs a compact, fully functional, vibration-free, and precisely temperature-controlled static gradient crystallization device. Example 2

[0036] This embodiment will describe in detail how to use the apparatus described in Embodiment 1 for solution crystallization purification, and will specifically illustrate the control method of the apparatus for solution crystallization purification of the present invention using sucrose aqueous solution as an example.

[0037] Before conducting any crystallization experiments, the assembly and debugging of the apparatus must be completed. First, carefully pour the liquid to be crystallized (in this example, 200 mL of a 60% sucrose aqueous solution) into a clean glass beaker 1. Second, place the glass beaker 1 stably on the heat-conducting pad 7 of the lower TEC module 3, ensuring good contact between the bottom of the beaker and the heat-conducting pad 7. Third, loosen the locking knob on the support adjustment assembly, operate the slider, and slowly lower the upper TEC module 2 along the guide rail 4, closely observing the Teflon-coated working surface of its cooling end. Stop the descent immediately when it just touches the surface of the sucrose solution in the glass beaker 1, and tighten the locking knob to securely lock the upper TEC module 2 at this height. Fourth, check that the cylindrical copper heat sinks 9 on both TEC modules are securely installed and tightly fitted to the non-working surfaces of the TEC modules, while ensuring that the air passages around the heat sinks 9 are unobstructed and free of any obstructions. Fifth, using signal cables, connect the temperature sensors on the two TEC modules and the power interface of the TEC itself to the corresponding interface on the control component's electrical control box 6. At this point, the physical connection and debugging of the device are complete, and it is ready to enter the parameter setting and operation phase.

[0038] Next, parameter settings are performed. The parameter setting interface is accessed via the touchscreen control panel on the control box 6. Based on the thermodynamic properties of the target solute and the desired crystal morphology, the experimenter needs to set two key temperature parameters: the target temperature T1 of the upper TEC module 2 and the target temperature T2 of the lower TEC module 3. In the sucrose crystallization experiment of this embodiment, we aim to construct a vertical temperature gradient that gradually decreases from top to bottom, i.e., a higher temperature at the upper surface of the solution and a lower temperature at the bottom. Such a temperature gradient helps the solute preferentially nucleate and grow upwards in the low-temperature region at the bottom. In this embodiment, the target temperature T1 of the upper TEC module 2 is set to 40°C, and the target temperature T2 of the lower TEC module 3 is set to 10°C, thereby forming a stable vertical temperature gradient of approximately 30°C in a 200mL solution column. Simultaneously, the holding time, i.e., the total duration for maintaining this temperature gradient for static crystallization, is set on the control panel; in this embodiment, it is set to 12 hours. After setting, the control program is started.

[0039] After the control program starts, controller 5 first sends initial drive commands to the TEC drive module according to preset T1 and T2. The upper TEC module 2 needs to achieve a "cooling end" temperature of 40°C. Since its cooling end is in contact with the solution, this means its non-working surface (hot end) temperature will be higher. Similarly, the lower TEC module 3 needs to achieve a "cooling end" temperature of 10°C, and its non-working surface (hot end) also needs to be cooled by a heat sink. Controller 5 automatically adjusts the drive current based on real-time temperature feedback. For example, if the actual temperature of the upper TEC module 2 is below 40°C, controller 5 increases its drive current to generate more heat; conversely, if the actual temperature is above 40°C, it decreases or reverses the current (when cooling is needed). In this embodiment, after approximately 30 minutes of automatic adjustment, the temperatures of the two TEC modules stabilize at 40°C ± 0.1°C and 10°C ± 0.1°C, respectively. Throughout the stabilization and operation process, the two cylindrical copper heat sinks 9 continuously provide efficient passive cooling. They rapidly conduct the heat generated by the non-working surfaces of the TEC to the surrounding air through natural convection, ensuring that the TEC module can stably maintain the required temperature gradient for a long time. Since no fans are running throughout the process, the entire device is in a state of absolute silence and vibration-free operation, providing an ideal external environment for the orderly arrangement of sucrose molecules and crystal growth.

[0040] Driven by a stable temperature gradient, the crystallization process of the sucrose solution begins and continues. Because the temperature at the bottom (10°C) is lower than at the top (40°C), and the solubility of sucrose decreases with decreasing temperature, the sucrose reaches a supersaturated state at the bottom, initiating spontaneous nucleation. The initially formed tiny crystal nuclei act as seed crystals, attracting sucrose molecules from the surrounding solution to diffuse and deposit, promoting continuous crystal growth. Simultaneously, due to the higher temperature and better solubility of sucrose at the top, sucrose molecules in the solution replenish the bottom crystallization region from top to bottom through convection and diffusion. This dynamic equilibrium process allows the solute to precipitate directionally from bottom to top, rather than randomly nucleating within the container. The experimenters could clearly observe the entire process through the side wall of the transparent glass beaker 1: In the first few hours, tiny, sparkling crystal particles first appeared at the bottom of the beaker; as time went on, these crystal particles gradually grew and took on a regular shape; the crystals slowly extended and grew from the bottom to the solution area above, and finally, after 12 hours, the entire bottom and lower area of ​​the beaker were filled with sucrose crystals of uniform size and regular shape.

[0041] After the preset 12-hour heat preservation time is reached, the control component automatically shuts off the power to the upper TEC module 2 and the lower TEC module 3, ceasing active temperature control. At this time, the cylindrical copper radiator 9 continues to function, dissipating residual heat from the TEC modules and solution through natural convection, allowing the entire system to cool slowly and gently to room temperature. This natural cooling process avoids thermal stress and cracking damage to the crystals that could occur due to sudden temperature changes, thus preserving the crystal integrity. After the device has naturally cooled to room temperature, the experimenter carefully removes the glass beaker 1. Pouring out the residual mother liquor on the top layer yields the highly crystalline, well-formed sucrose crystals deposited at the bottom. Unlike the fluffy, finely powdered sugar obtained by natural evaporation or single-cooling crystallization methods, the crystals obtained using the device and method of this invention have larger particle size and more regular crystal habit, and their purity is significantly improved.

[0042] In summary, the apparatus and control method for solution crystallization purification provided by this invention, through a unique dual-TEC module layout, a height-adjustable upper module design, a fanless passive natural cooling system, and a precision temperature control strategy based on controller 5, successfully constructs a stable, vibration-free, material-compatible, and flexible static gradient crystallization platform. The above embodiments fully demonstrate that the apparatus and method achieve excellent results in solution crystallization purification, effectively overcoming the shortcomings of existing technologies, and possessing significant progress and broad industrial application prospects. The specific embodiments described above are merely preferred embodiments of this invention and are not intended to limit the scope of protection of this invention. Those skilled in the art can make several improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. An apparatus for solution crystallization and purification, characterized in that, include: container; Two TEC modules are located at the top and bottom of the container, respectively; The TEC module includes the TEC and a passive natural heat sink located at the heat dissipation end of the TEC; The lifting mechanism allows for adjustment of the height of the upper TEC module, ensuring that the cooling end of the upper TEC module contacts the liquid surface inside the container.

2. The apparatus for solution crystallization purification according to claim 1, characterized in that, The passive natural radiator has metal heat dissipation fins for heat exchange with the air.

3. An apparatus for solution crystallization purification according to claim 1 or 2, characterized in that, It also includes a vertical guide rail, on which the upper TEC module is connected and can slide up and down.

4. An apparatus for solution crystallization purification according to claim 1 or 2, characterized in that, The cooling end of the TEC module is made of metal.

5. The apparatus for solution crystallization purification according to claim 4, characterized in that, The cooling end of the upper TEC module is covered with a protective layer.

6. An apparatus for solution crystallization purification according to claim 1 or 2, characterized in that, It also includes temperature sensors located on the two TEC modules respectively.

7. The apparatus for solution crystallization purification according to claim 6, characterized in that, It also includes a control component, which includes a controller and a TEC drive module; the temperature sensor is connected to the controller via signal connection, and the TEC module is connected to the TEC drive module via signal connection.

8. An apparatus for solution crystallization purification according to claim 1 or 2, characterized in that, The container's sidewalls are transparent and visible.

9. An apparatus for solution crystallization purification according to claim 1 or 2, characterized in that, A thermal pad is provided between the cooling end of the lower TEC module and the bottom of the container.

10. A control method for an apparatus for solution crystallization purification, characterized in that, Includes the following steps: 1) Place the liquid to be crystallized in the container, with the cooling end of the upper TEC module in contact with the liquid surface inside the container, and the lower TEC module in close contact with the bottom of the container; 2) Connect the two TEC modules to the control component via signals; 3) Set the target temperature T1 for the upper TEC module and the target temperature T2 for the lower TEC module, with T1 being higher than T2; 4) Start the upper and lower TEC modules. The controller will automatically adjust the TEC drive current to stabilize the temperature of the upper TEC module to T1 and the temperature of the lower TEC module to T2. 5) Under a stable temperature gradient, the solute in the solution precipitates out directionally from bottom to top, initiating the static crystallization process; 6) After the preset heat preservation time is reached, turn off the two TEC modules, remove the container, and complete the crystallization operation.

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