A high-salinity wastewater low-temperature crystallization freezing desalination device and design method

Abstract

This invention discloses a cryogenic desalination device and design method for low-temperature crystallization of high-salinity wastewater. The device includes a freezing chamber and a chiller. One side of the freezing chamber is connected to an inlet, and the other side is connected to an outlet. The freezing chamber is cooled by the chiller. Multiple partition walls divide the freezing chamber into multiple freezing chambers, which are interconnected. Each freezing chamber contains a freezing frame, and each freezing chamber has a door on one side. The door has a main locking mechanism and two auxiliary locking mechanisms. When the door is opened, the auxiliary locking mechanisms control whether the freezing frame pops out or not. This invention solves the problem of difficult ice removal by setting multiple freezing chambers within the freezing chamber and equipping each chamber with a freezing frame and a sliding side plate, allowing the ice layer to adhere to the freezing frame instead of freezing to the inner wall of the freezing chamber. Once the ice layer has formed, the door can be opened to remove the freezing frame along with the ice layer, avoiding ice breakage and contamination.

Description

Technical Field

[0001] This invention relates to the field of water treatment, specifically to a cryogenic desalination device and design method for low-temperature crystallization of high-salt wastewater. Background Technology

[0002] High-salinity industrial wastewater is a typical type of wastewater generated during the production processes of industries such as chemical, pharmaceutical, textile, and mining. Its total dissolved solids content typically exceeds 3.5 wt%, and it is often accompanied by various heavy metal ions and organic pollutants. Direct discharge of this type of wastewater without proper treatment can lead to soil salinization, increased salinity of surface and groundwater, and damage to the ecological environment. Currently, commonly used technologies for treating high-salinity wastewater include reverse osmosis, electrodialysis, and multi-effect evaporation, but all suffer from problems such as membrane fouling, high energy consumption, and severe equipment corrosion. In recent years, cryogenic desalination technology has gradually gained attention due to its advantages such as low operating temperature, strong tolerance to corrosive substances, and no need for the addition of chemical reagents.

[0003] The basic principle of cryogenic desalination is to utilize the repulsive effect of water on salt during freezing. When brine is slowly cooled, water molecules preferentially form ice crystals, while salt is displaced into the unfrozen liquid phase, thus separating the ice crystals from the concentrated brine. The migration patterns of salt during freeze-thaw cycles indicate that the purity of the ice crystals is jointly determined by the advancement rate of the crystallization front, the initial salt concentration, and the freezing temperature. Under ideal directional freezing conditions, salt can be effectively driven away from the ice crystals, forming a nearly pure ice layer. However, current technologies have not fully explored this principle. Most studies remain at the qualitative description level, lacking a systematic determination of the quantitative relationship between the advancement rate of the crystallization front and time, temperature, and concentration. Furthermore, the functional relationship between the solute partition coefficient and the freezing rate has not yet been clearly expressed mathematically, making it impossible to accurately obtain the optimization window between freezing time, ice layer thickness, and desalination effect through theoretical calculations. In other words, the design of cryogenic desalination processes still relies on empirical trial and error, lacking scientific guidance at the algorithmic level.

[0004] Based on this, applying the above principles to actual wastewater treatment equipment presents further engineering challenges. Most existing cryogenic desalination equipment uses a static freezing method, placing the wastewater to be treated in a freezing container and cooling it with an surrounding cold source until it freezes. This method has two main drawbacks: First, once the ice layer forms, it firmly adheres to the inner wall and bottom of the container. Removing the ice layer often requires knocking or scraping, easily causing it to break. On the one hand, broken ice is difficult to use directly for subsequent experimental analysis, making it impossible to accurately determine the ice quality under different freezing conditions, thus making it difficult to determine the optimal freezing conditions and consequently, the optimal desalination device. On the other hand, broken ice contaminates the wastewater, and the broken ice crystals carry concentrated brine, significantly reducing the desalination effect. Second, for convenient ice removal, some equipment has a retractable freezing frame inside the freezing container, causing the ice to form on the freezing frame rather than freezing directly on the inner wall of the container. When removing ice, the operator first opens the door and then manually pulls out the freezing frame. While this design alleviates the problem of ice sticking, the manual pulling operation is rather cumbersome, especially when multiple freezing chambers are working at the same time. Removing ice from each chamber takes a long time and affects processing efficiency.

[0005] To improve operational convenience, some improvement solutions attempt to link the freezing frames with the cabinet door, meaning the freezing frames automatically pop out when the door is opened. However, existing linkage mechanisms typically use rigid connections or fixed transmission ratios, making it impossible to flexibly switch the linkage state according to the operator's actual needs. In practice, operators may want to keep the freezing frames stationary while only opening the cabinet door in certain situations, such as when only observing the ice formation, performing equipment maintenance, or cleaning residual concentrated brine, to avoid accidental movement of the freezing frames, resulting in ice collision damage, water dripping into the operating area, or occupying extra space. Furthermore, when the ice maturity in different freezing chambers is inconsistent, operators may need to remove some freezing frames first, allowing others to continue freezing. In such cases, a fixed linkage design cannot meet the need for selective ice removal.

[0006] In summary, existing technologies suffer from two shortcomings: first, the lack of quantitative and algorithmic exploration of salt migration patterns during cryogenic desalination prevents the scientific optimization of key parameters such as freezing time and ice thickness; second, even with an understanding of these patterns, there is a lack of equipment structures capable of on-demand linkage and hierarchical locking control to achieve efficient operation guided by these patterns. This application addresses these issues by first exploring the algorithmic patterns of cryogenic desalination through experimental measurements and theoretical modeling, and then designing a cryogenic desalination device with a hierarchical locking mechanism and switchable linkage functions, thereby translating the understanding of these patterns into engineering applications. Summary of the Invention

[0007] The purpose of this invention is to provide a cryogenic desalination device and design method for low-temperature crystallization of high-salt wastewater, so as to solve the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a cryogenic desalination device for low-temperature crystallization of high-salt wastewater, comprising a freezing box and a cooler, wherein one side of the freezing box is connected to an inlet and the other side is connected to an outlet, the freezing box is cooled by the cooler, the freezing box is provided with multiple partition walls, the partition walls divide the freezing box into multiple freezing chambers, the multiple freezing chambers are interconnected, each freezing chamber is provided with a freezing frame, and each freezing chamber is provided with a door on one side; The cabinet door is equipped with a main locking mechanism and two auxiliary locking mechanisms. When the cabinet door is opened, the auxiliary locking mechanisms can control the freezing frame to pop out or not pop out. The main locking mechanism includes a locking gear and a locking rack, the locking rack being able to slide out of the cabinet door and insert into the freezer to form a lock; The auxiliary locking mechanism includes an arc-shaped plate, which can achieve auxiliary locking, linkage with the freezing frame, or non-linkage with the freezing frame by different rotation positions; Both sides of the freezing frame are provided with pushing components, each pushing component corresponds to one of the auxiliary locking mechanisms, and the pushing components are set in the wall of the freezing box; The pushing assembly includes a scissor-type base rod, a fixed slide rail, and a movable slide rail. The angle of the scissor-type base rod is controlled by adjusting the distance between the movable slide rail and the fixed slide rail, thereby enabling the freezing frame to be pushed out.

[0009] Preferably, the main locking mechanism further includes a main locking shaft, one end of which is fixedly connected to a handwheel. The main locking shaft has a thread in the middle and a spline shaft at its lower end. The middle part of the main locking shaft is threaded to the door. The spline shaft portion at the lower end of the main locking shaft is slidably connected to a locking gear. The locking gear meshes with a locking rack. The locking gear is rotatably connected to the door, and the locking rack is slidably connected to the door. The handwheel is exposed outside the door.

[0010] Preferably, the auxiliary locking mechanism further includes an auxiliary locking shaft, one end of which is fixedly connected to an auxiliary locking wrench. The middle of the auxiliary locking shaft is threaded, and its lower end is a splined shaft. The middle of the auxiliary locking shaft is threaded to the cabinet door. The splined shaft portion at the lower end of the auxiliary locking shaft is slidably connected to an arc-shaped plate. The arc-shaped plate is in contact with a cam. The auxiliary locking wrench is exposed outside the cabinet door. The arc-shaped plate is rotatably connected to the cabinet door and can be partially exposed outside the cabinet door and inserted into the freezer to achieve locking.

[0011] Preferably, the bottom surface of the freezing frame is not closed, and a sliding side plate is provided on each side of the freezing frame. The freezing frame is placed between the two sliding side plates, and the sliding side plates are in contact with the inner wall of the freezing box and the partition wall. A sliding boss is provided on the sliding side plate, and the sliding boss is slidably connected to the surface of the freezing box or the partition wall. The sliding boss is connected to a pushing component.

[0012] Preferably, multiple scissor-type base rods are provided, with every two scissor-type base rods intersecting in an X-shape, and their middle parts are hinged to each other to form a scissor-type rod group. The ends of the scissor-type base rods of multiple scissor-type rod groups are hinged to each other by hinge pins to form scissor rods. One end of one scissor-type base rod is hinged to a sliding boss, and the other end of one scissor-type base rod is hinged to the inner wall surface of the freezer or partition wall.

[0013] Preferably, the fixed slide rail and the movable slide rail are respectively slidably connected by upper and lower hinge pins. The fixed slide rail is fixedly connected to the freezer or partition wall, and the movable slide rail is vertically slidably connected to the freezer or partition wall. A slide rail spring is provided between the fixed slide rail and the movable slide rail to separate the two.

[0014] Preferably, a slide rail inclined block is fixedly connected to the movable slide rail, the slide rail inclined block is in contact with the push inclined block, the push inclined block is fixedly connected to one end of the inclined block push rod, the other end of the inclined block push rod is in contact with the cam, the slide rail inclined block, the push inclined block, and the inclined block push rod are slidably connected in the freezer or partition wall, and the push inclined block is provided with a spring for resetting.

[0015] Preferably, the cam is slidably connected to the cam spline shaft, the cam spline shaft is fixedly connected to the cabinet door, the cabinet door is hinged to the freezer, the hinge position of the cam spline shaft and the cabinet door is coaxially arranged, and a cam spring is provided between the cam and the cabinet door, the cam spring surrounding the cam spline shaft.

[0016] A design method for a cryogenic desalination device for low-temperature crystallization of high-salt wastewater, the steps of which are as follows: Step 1: Determine the solute migration law and crystallization front advancement speed of brine during the freeze-crystallization process; obtain the ice crystal growth rate and salt enrichment concentration distribution in the unfrozen area of ​​brine under different initial salt concentrations and different freezing temperatures through experiments, establish the quantitative relationship between solute partition coefficient and freezing speed, and determine the advancement speed v(t) of the crystallization front along the freezing direction. Step 2: Establish the optimal relationship between freezing time and ice thickness; based on the crystallization propagation rate v(t) obtained in Step 1, and with the target ice purity as a constraint, determine the optimal freezing time window t through theoretical calculations or semi-empirical models. opt This makes the ice thickness H within that time window... iceTo reach maximum without significant salt inclusions or dendrite encapsulation; Step 3: Design an orthogonal experimental design and conduct physical experiments; select key structural and operational parameters affecting the cryogenic desalination effect as design variables, including: freezing chamber height, freezing chamber width, cold air inlet velocity, cold air temperature, and number of partition walls; select multiple levels for each variable and arrange the experiments using an orthogonal array; conduct cryogenic desalination experiments on a physical prototype or small experimental platform, and measure the response indicators: average ice layer thickness, ice crystal salinity, freezing time, and ice integrity; record the results of each group of experiments; Step 4: Establish a response surface model and optimize structural parameters; Based on the experimental data from Step 3, construct a response surface surrogate model using quadratic polynomial regression or radial basis functions, with minimizing ice crystal salinity and freezing time within a preset window as the main optimization objectives, and ice integrity as the constraint; Determine the optimal range of values ​​for each structural parameter through response surface analysis; Optimize the response surface model using gradient descent or genetic algorithms to obtain the optimal combination of structural parameters that yields the best comprehensive index; Step 5: Determine the final design parameters of the cryogenic desalination device based on the optimization results; use the structural parameters obtained in Step 4 as the basis for manufacturing the cryogenic desalination device, so that the device can perform cryogenic desalination operation according to the optimal freezing time determined in Step 2 during operation.

[0017] Compared with existing technologies, the advantages of this invention are as follows: By setting partition walls inside the freezing chamber to form multiple interconnected freezing cavities, and installing a freezing frame and sliding side plate that fits against the inner wall of each freezing cavity, the ice layer adheres to the freezing frame without freezing to the inner wall of the freezing cavity. The freezing frame can be removed entirely along with the ice layer, solving the problem of difficult ice removal. The intact ice layer can be directly used for subsequent experimental analysis, allowing for accurate assessment of the ice quality under different freezing conditions, facilitating the determination of optimal freezing conditions, and thus providing a reliable basis for obtaining the optimal desalination device. In use, once the ice layer has formed, simply opening the chamber door allows the freezing frame and ice layer to be removed, avoiding the problems of ice breakage, detachment, and contamination by concentrated brine caused by knocking and scraping in traditional methods.

[0018] This invention employs a top-down freezing method, where cold air is blown downwards from the top of the freezing chamber, causing the wastewater to freeze gradually from top to bottom. This method facilitates the migration of salts to the lower concentrated aqueous phase, promoting higher ice crystal purity. Simultaneously, a liquid level observation window is installed on the chamber door to monitor the water level and freezing status in real time, allowing for control of the freezing process.

[0019] This invention achieves door sealing through the cooperation of a main locking mechanism and an auxiliary locking mechanism. The main and auxiliary locking mechanisms use threaded locking to ensure stable door closure, while the auxiliary locking mechanism allows for optional automatic pop-out of the freezer compartment when the door is opened, facilitating operation.

[0020] The freezer frame of this invention uses a scissor-type base rod pushing assembly to achieve pop-out. When the scissor rod is pushed by the inclined block push rod, the angle changes and it extends, thereby pushing the sliding boss and moving the freezer frame out. When the freezer frame is pulled out, it compresses the scissor rod assembly in the opposite direction. With the help of the springs, the device can automatically reset when no external force is applied, making it convenient to use.

[0021] This invention establishes a quantitative law for cryogenic desalination, enabling scientific optimization of parameters. First, through systematic freezing experiments, this invention determines the quantitative relationship between the crystallization front advance velocity v(t) and the solute partition coefficient K under different initial salt concentrations and freezing temperatures. Based on this, and constrained by the ice crystal salinity, the ice layer thickness H is established. ice Integral model H with freezing time t ice (t)=∫v(τ)dτ, and the optimal freezing time window was obtained through optimization. This discovery has shifted the cryogenic desalination operation from empirical trial and error to quantitative design.

[0022] This invention optimizes the structural parameters of the device based on orthogonal experiments and response surface methodology. The invention selects several key parameters, including the height and width of the freezing chamber, cold air velocity, cold air temperature, and the number of partition walls. Multiple sets of physical experiments are arranged using orthogonal arrays to measure four response indicators: ice layer thickness, ice crystal salinity, freezing time, and ice extraction integrity. A highly fitted response surface model is constructed through quadratic polynomial regression, and the optimal combination of structural parameters is obtained through genetic algorithm optimization, thus determining the device parameters. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the main structure of the present invention; Figure 2 This is a schematic diagram of the structure of the freezer of the present invention; Figure 3 This is a schematic diagram of the structure of the component driving the present invention; Figure 4 for Figure 3 A magnified view of a portion at point A; Figure 5 for Figure 3 A magnified view of a portion at point B; Figure 6 for Figure 3 A magnified view of a portion at point C; Figure 7 This is a schematic diagram of the structure of the freezing frame of the present invention; Figure 8 This is a structural schematic diagram of the freezing frame of the present invention from another angle; Figure 9 for Figure 8 A magnified view of a portion at point D; Figure 10This is a schematic diagram of the main locking mechanism of the present invention; Figure 11 This is a schematic diagram of the design process of the present invention.

[0024] In the diagram: 1. Freezer, 101. Partition wall, 102. Freezer cavity, 2. Refrigerator, 3. Door, 301. Handwheel, 302. Main locking shaft, 303. Locking gear, 304. Locking rack, 305. Auxiliary locking wrench, 306. Auxiliary locking shaft, 307. Arc plate, 4. Freezer frame, 401. Sliding side plate, 402. Sliding boss, 5. Scissor base rod, 501. Hinge pin, 502. Fixed slide rail, 503. Movable slide rail, 504. Slide rail spring, 505. Slide rail inclined block, 506. Pushing inclined block, 507. Inclined block push rod, 508. Cam, 509. Cam spline shaft, 510. Cam spring. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see Figure 1-10To address the lack of an on-demand switching linkage control mechanism in existing devices, which leads to insufficient operational flexibility and adaptability, this new system allows for the selection of whether the freezing frame automatically pops out when the door is opened, facilitating operation. The ice layer adheres to the freezing frame and does not freeze on the inner wall of the freezing chamber, thus solving the problem of difficult ice removal. In use, once the ice layer has formed, simply open the door to remove the freezing frame along with the ice layer, avoiding the ice layer breaking off and becoming contaminated. This invention provides a technical solution: a cryogenic desalination device for low-temperature crystallization of high-salt wastewater, comprising a freezing chamber 1 and a cooler 2. The freezing chamber 1 has an inlet on one side and an outlet on the other. The freezing chamber 1 is cooled by the cooler 2, which delivers cold air into each freezing chamber 102 of the freezing chamber 1, causing freezing from top to bottom. The freezing chamber 1 is equipped with a liquid level observation window made of transparent material such as acrylic or glass to observe the liquid level and freezing status. Multiple partition walls 101 are installed inside the freezing chamber 1, dividing it into multiple freezing chambers 102. These chambers 102 are interconnected. Each freezing chamber 102 contains a freezing frame 4, and each freezing chamber 102 has a door 3 on one side. In this application, the electrical components such as the motor, cylinder, push rod, and cooler are all existing models. In use, add the wastewater to be desalinated into the freezer 1 through the inlet. Observe the water level through the observation window. The water level should be above the freezing frame 4 and below the sliding boss 402 of the sliding side plate 401. After adding water, start the refrigeration unit 2. The refrigeration unit 2 sends cold air through the pipes into each freezing chamber 102 of the freezer 1. The cold air blows from top to bottom, causing the wastewater to freeze from top to bottom. Since the freezing frame 4 and the sliding side plate 401 are in close contact with the inner wall of the freezing chamber 102, the ice layer will only freeze on the freezing frame 4 and not on the inner wall of the freezing chamber 102. Observe the freezing situation through the observation window. When the thickness of the frozen ice layer reaches the lowest position of the freezing frame 4, turn off the refrigeration unit 2 and drain the wastewater through the outlet. At this time, there is no water left in the freezer 1. You can then open the door 3 to remove the desalinated ice layer, thus completing the purification process. Figure 4 This is a schematic diagram of a scissor bar. Figure 5 This is a schematic diagram of the slide rail spring and the slide rail inclined block. Figure 6 This is a schematic diagram showing the positional relationship between the curved plate and the cam. Figure 9 A schematic diagram showing the positions of the curved plate and cam in the box door.

[0027] To ensure the closure of the door 3, a sealing strip is installed between the door 3 and the freezer compartment 1. The door 3 is equipped with a main locking mechanism and two auxiliary locking mechanisms. When the door 3 is opened, the auxiliary locking mechanisms can control whether the freezer frame 4 pops out or not. The main locking mechanism includes a locking gear 303 and a locking rack 304. The locking rack 304 can slide out of the door 3 and insert into the freezer compartment 1 to form a lock. The auxiliary locking mechanism includes an arc-shaped plate 307. The arc-shaped plate 307 can achieve auxiliary locking, linkage with the freezer frame 4, or non-linkage of the freezer frame 4 by different rotation positions. When it is necessary to open, first unlock the two auxiliary locking mechanisms, adjust the position of the auxiliary locking mechanisms according to whether the freezer frame 4 needs to pop out, and after adjustment, unlock the main locking mechanism to open the door 3 upward. When it is necessary to lock the door 3, first close the door 3, then lock the main locking mechanism first, and then lock the auxiliary locking mechanisms to press the door 3 and the freezer compartment 1 together, thus completing the closure of the door 3.

[0028] To facilitate the sliding out of the freezer frame 4, push components are provided on both sides of the freezer frame 4. Each push component corresponds to an auxiliary locking mechanism. The push components are set in the wall of the freezer box 1. The push components include a scissor base rod 5, a fixed slide rail 502, and a movable slide rail 503. The angle of the scissor base rod 5 is controlled by adjusting the distance between the movable slide rail 503 and the fixed slide rail 502, thereby realizing the push-out of the freezer frame 4. The bottom of the freezing frame 4 is not closed. A sliding side plate 401 is provided on each side of the freezing frame 4. The freezing frame 4 is placed between the two sliding side plates 401. The sliding side plates 401 are provided with a base support such as an angle iron to support the freezing frame 4 stably. The freezing frame 4 is detachable so that the freezing frame 4 and the ice block can be removed together when freezing is complete without crushing the ice. The sliding side plates 401 are in contact with the inner wall of the freezing box 1 and the partition wall 101. The sliding side plates 401 are provided with sliding bosses 402. The sliding bosses 402 are slidably connected to the wall of the freezing box 1 or the partition wall 101. The sliding bosses 402 are connected to the pushing component. As needed, the freezing frame 4 can pop out with the opening of the cabinet door 3, or it can be pulled out manually. When the freezing frame 4 pops out, it is driven by the scissor-type base rod 5. The scissor-type base rod 5 pushes the sliding boss 402 to move, the sliding boss 402 drives the sliding side plate 401 to move, and the sliding side plate 401 drives the freezing frame 4 to move. When the freezing frame 4 is pulled out, it compresses the scissor-type base rod 5. A baffle strip, made of rubber, silicone or steel, can be set on the bottom surface of the freezing frame 4 to support the ice layer. When removing ice, let the freezing frame 4 pop out and wait a moment, and the ice layer will detach from the surrounding sliding side plate 401, making it easy to walk the freezing frame 4 with the ice layer attached. To avoid interference, the upper front end of the sliding side plate 401 can be set to a retracted state such as an arc.

[0029] To ensure the tight closure of the door 3, the main locking mechanism also includes a main locking shaft 302. One end of the main locking shaft 302 is fixedly connected to a handwheel 301. The main locking shaft 302 has a thread in the middle and a spline shaft at its lower end. The main locking shaft 302 is threadedly connected to the door 3 in the middle. The spline shaft at the lower end of the main locking shaft 302 is slidably connected to a locking gear 303. The locking gear 303 meshes with a locking rack 304. The locking gear 303 is rotatably connected in the door 3, and the locking rack 304 is slidably connected in the door 3. The handwheel 301 is exposed outside the door 3. When opening, grasp the handwheel 301 and turn it. The handwheel 301 drives the main locking shaft 302 to rotate, which in turn drives the locking gear 303 to rotate. The locking gear 303 drives the locking rack 304 to move and retract into the door 3. To lock and close the door 3, simply reverse the handwheel 301. During this process, the main locking shaft 302 will experience a slight axial displacement due to its threaded connection with the door 3. The spline shaft part compensates for this displacement to ensure that the main locking shaft 302 can always drive the locking gear 303 to rotate. The threaded connection locks the rotation position of the handwheel 301, thereby ensuring the stable closing of the door 3. Furthermore, the insertion position of the locking rack 304 on the freezer 1 can be set with an inclined surface so that the door 3 is pressed against the freezer 1 as the locking rack 304 extends.

[0030] To further lock the door 3, the auxiliary locking mechanism also includes an auxiliary locking shaft 306. One end of the auxiliary locking shaft 306 is fixedly connected to an auxiliary locking wrench 305. The middle part of the auxiliary locking shaft 306 is threaded, and its lower end is a splined shaft. The middle part of the auxiliary locking shaft 306 is threaded to the door 3. The splined shaft part at the lower end of the auxiliary locking shaft 306 is slidably connected to an arc plate 307. The arc plate 307 is in contact with a cam 508. The auxiliary locking wrench 305 is exposed outside the door 3. The arc plate 307 is rotatably connected to the door 3 and can be partially exposed outside the door 3 and inserted into the freezer 1 to achieve locking. In the locked state, the auxiliary locking lever 305 is in the initial position with an angle of 0°. The end of the arc plate 307 closest to the rotation center rests against the cam 508. At this time, the cam 508 and the inclined block push rod 507 are misaligned, and the cam 508 will not drive the inclined block push rod 507 to prevent the freezer frame 4 from moving and colliding with the door 3 when the door 3 is closed. When the auxiliary locking lever 305 is turned to unlock, the auxiliary locking lever 305 rotates a certain angle, driving the auxiliary locking shaft 306 to rotate. The auxiliary locking shaft 306 drives the arc plate 307 to rotate, and the arc plate 307 retracts into the door 3. Due to the threaded connection between the auxiliary locking shaft 306 and the door 3, a slight axial displacement will occur. The splined shaft part compensates for this displacement to ensure that the auxiliary locking shaft 306 can always drive the arc plate 307 to rotate. The threaded connection achieves the locking mechanism... Locking the rotation position of the arc plate 307: When the auxiliary locking lever 305 rotates 90°, the arc plate 307 is fully retracted into the door 3. The middle part of the arc plate 307, that is, the contact position of the arc plate 307 slightly away from the rotation center, contacts the cam 508. At this time, the arc plate 307 pushes the cam 508 to the position of the inclined block push rod 507. The cam 508 can drive the inclined block push rod 507, and the cam spring 510 is compressed. In this state, the door 3 can be opened to drive the freezer frame 4 to extend. When the auxiliary locking lever 305 rotates 180°, the arc plate 307 at its farthest point from the rotation center abuts against the cam 508, pushing the cam 508 and the inclined block push rod 507 into a misaligned state again. The cam 508 will not drive the inclined block push rod 507. At this time, the door 3 will not be opened to drive the freezer frame 4 to extend.

[0031] To facilitate the extension of the freezer frame 4, multiple scissor-type base rods 5 are provided. Each pair of scissor-type base rods 5 are arranged in an X-shape, with their middle sections hinged together to form a scissor-type rod group. The ends of the scissor-type base rods 5 in multiple scissor-type rod groups are hinged together by hinge pins 501 to form scissor rods. One end of one scissor-type base rod 5 is hinged to a sliding boss 402, and the other end of one scissor-type base rod 5 is hinged to the inner wall of the freezer box 1 or partition wall 101. The fixed slide rail 502 and the movable slide rail 503 are slidably connected to the upper and lower hinge pins 501, respectively. The fixed slide rail 502 is fixedly connected to the freezer box 1 or partition wall 101, and the movable slide rail 503 is vertically slidably connected to the freezer box 1 or partition wall 101. A slide rail spring 504 is provided between the fixed slide rail 502 and the movable slide rail 503 to maintain the distance between them. To reduce friction and limit the sliding direction, a guide block with a groove and a ball bearing to reduce friction can be provided on the movable slide rail 503. A slide rail inclined block 505 is fixedly connected to the movable slide rail 503. The slide rail inclined block 505 is in contact with a push inclined block 506. The push inclined block 506 is fixedly connected to one end of an inclined block push rod 507. The other end of the inclined block push rod 507 is in contact with a cam 508. The slide rail inclined block 505, the push inclined block 506, and the inclined block push rod 507 are slidably connected in the freezer 1 or the partition wall 101. A spring for resetting is provided on the push inclined block 506, and the spring is fixedly connected in the freezer 1 or the partition wall 101. The cam 508 is slidably connected to the cam spline shaft 509, the cam spline shaft 509 is fixedly connected to the door 3, the door 3 is hinged to the freezer 1, the hinge position of the cam spline shaft 509 and the door 3 is coaxially set, and a cam spring 510 is provided between the cam 508 and the door 3, the cam spring 510 is wrapped around the cam spline shaft 509. When the cabinet door 3 opens and causes the freezer frame 4 to extend, the cam 508 pushes the inclined block push rod 507, which in turn pushes the inclined block 506. Due to the inclined plane, the inclined block 506 pushes the slide rail inclined block 505 to move downward. The slide rail inclined block 505 causes the movable slide rail 503 to move downward and compress the slide rail spring 504. The downward movement of the movable slide rail 503 changes the angle of the scissor base rod 5, thereby extending the entire scissor rod. The scissor rod drives the sliding boss 402 to slide, thereby pushing the freezer frame 4 to extend. When the freezer frame 4 is manually pulled out, the driving relationship is reversed. In the state of no force, each spring pushes each component to reset.

[0032] Please see Figure 11 A design method for a cryogenic desalination device for low-temperature crystallization of high-salt wastewater, comprising the following steps: Step 1: Determine the solute migration pattern and crystallization front advancement speed of brine during the freeze-crystallization process; obtain the ice crystal growth rate and salt enrichment concentration distribution in the unfrozen area of ​​brine during directional freezing under different initial salt concentrations (1wt%~10wt%) and different freezing temperatures (-5℃~-20℃) through experiments, establish the quantitative relationship between solute partition coefficient and freezing rate, and determine the advancement speed v(t) of the crystallization front along the freezing direction; Experimental preparation: Experimental materials: Simulated lake water, i.e. NaCl solution, was selected as the research object. Salt water samples with different initial salt concentrations were prepared, and multiple parallel samples were set up for each concentration group to avoid experimental errors. Experimental equipment: Low temperature constant temperature test chamber (temperature control accuracy ±0.1℃, temperature range -30℃~25℃), microscope (magnification 100~500x, with image acquisition system), conductivity meter (accuracy ±0.01mS / cm), electronic balance (accuracy 0.0001g), data acquisition instrument (sampling frequency 1 time / minute); Experimental environment: The laboratory temperature is controlled at 20±1℃ and the humidity at 50±5% to avoid environmental factors from interfering with the freezing process.

[0033] Experimental operation procedure: A certain amount of saline samples with different initial salt concentrations were injected into the freezing mold, and the mold was placed in a low-temperature constant temperature test chamber. Different freezing temperatures were set, and timing was started after the test chamber temperature stabilized. The ice crystal growth process is observed in real time using a microscope, and the morphology and size of ice crystals at different time points are recorded using an image acquisition system. The ice crystal growth rate is analyzed using software. Every so often, a small amount of sample is taken from the unfrozen area (saline area) using a sampling needle, and its conductivity is measured by a conductivity meter. The concentration of salt enrichment in the unfrozen area is calculated by combining the standard curve. Samples are taken multiple times at each time point, and the average value is taken. The position of the crystallization front (the interface between ice crystals and unfrozen brine) was observed and recorded using a microscope. The propagation velocity v(t) of the crystallization front along the freezing direction at different time points was calculated. The formula for calculating the propagation velocity is as follows: ; In the formula: v(t): the advance velocity of the crystallization front at time t (mm / min); Δh: the position difference of the crystallization front between two adjacent time points (mm); Δt: the time interval (min).

[0034] Experimental data recording and analysis: Solute partition coefficient calculation: The solute partition coefficient K is defined as the ratio of the solute concentration in the ice crystals to the solute concentration in the unfrozen area. It is a key parameter for measuring the effectiveness of freeze-drying. The calculation formula is as follows: ; Where: K: solute partition coefficient (unitless); C i Salt concentration in ice crystals (wt%); C l Salt concentration of brine in unfrozen areas (wt%).

[0035] Then, experimental data were recorded, including the ice crystal growth rate, salt enrichment concentration in the unfrozen area, and crystallization front advancement speed under different conditions.

[0036] The experimental data at freezing temperatures all follow the rule that the longer the freezing time, the lower the ice crystal growth rate, the lower the crystallization front advance speed, the higher the salt enrichment concentration in the unfrozen area, and the lower the solute partition coefficient K. Specific values ​​can be supplemented based on actual experimental measurements, and the error of parallel samples should be controlled within ±5%.

[0037] Establishing the quantitative relationship: Using the crystallization front advancement velocity v(t) as the independent variable and the solute partition coefficient K as the dependent variable, a linear fit was performed using Origin software to establish the quantitative relationship between the two. The fitting formula is as follows: K = a∙v(t) + b; In the formula: a and b are fitting constants, which are calculated from experimental data.

[0038] Step 2: Establish the optimal relationship between freezing time and ice thickness; based on the crystallization propagation rate v(t) obtained in Step 1, and with the target ice purity as a constraint, determine the optimal freezing time window t through theoretical calculations or semi-empirical models. opt This makes the ice thickness H within that time window... ice It reaches its maximum without significant salt inclusions or dendrite inclusions.

[0039] The constraints are clearly defined: Core constraint: Target ice purity. Based on the quantitative relationship between the solute partition coefficient K obtained in step one and the crystallization front propagation velocity v(t), the ice crystal salinity C can be derived. i The calculation formula is as follows: ; In the formula: C l The salt enrichment concentration (wt%) in the unfrozen area can be obtained by fitting the experimental data from step one with the freezing time t: c1 = c0∙e kt (C0 is the initial salt concentration, and k is the enrichment coefficient, which is determined by fitting experimental data).

[0040] Ice thickness calculation model: Based on the crystallization front propagation velocity v(t), the ice thickness H ice The relationship with freezing time t is in integral form: ; In the formula: H ice (t): Ice thickness at time t (mm); τ: Integral variable (min); v(τ): Advance velocity of the crystallization front at time τ (mm / min).

[0041] Combining the relationship between v(t) and t obtained in step one (v(t) decreases as t increases), the fitted expression is v(t) = v0∙e -kt (where v_0 is the initial propulsion velocity of the crystallization front and k is the attenuation coefficient). After integration, a simplified formula for calculating the ice thickness is obtained: .

[0042] Determining the optimal freezing time window: A semi-empirical model is adopted, with the salinity of ice crystals as a constraint and the ice thickness H as the limiting factor. ice With the goal of maximizing, establish the optimization objective function: Objective function: ; Constraints: ; The above optimization problem was solved using Matlab software to obtain the optimal freezing time window tpt.

[0043] Verification experiment: Multiple time points were selected within the optimal freezing time window to conduct repeated experiments to verify whether the ice layer thickness and ice crystal salinity met the requirements.

[0044] Step 3: Design an orthogonal experimental design and conduct physical experiments; select key structural and operational parameters affecting the cryogenic desalination effect as design variables, including: freezing chamber height, freezing chamber width, cold air inlet velocity, cold air temperature, and number of partition walls; select multiple levels for each variable and arrange the experiments using an orthogonal array; conduct cryogenic desalination experiments and measure response indicators: average ice layer thickness, ice crystal salinity, freezing time, and ice integrity (whether it adheres to the wall surface); record the results of each group of experiments; Determination of experimental variables and levels: Several key parameters affecting the cryogenic desalination effect were selected as design variables, and each variable was assigned multiple levels. The specific variables and levels are as follows: Orthogonal experimental design: Since there are multiple factors, each with multiple levels, an orthogonal array is used to arrange the experiment.

[0045] Physical Experiment Implementation and Data Recording: Experimental setup: The setup includes a freezing chamber (different sizes can be used, made of stainless steel), a cooling system (adjustable wind speed and temperature), a partition wall (removable), and a data acquisition system (same as step one). Experimental procedure: For each group of experiments, brine with an initial salt concentration was injected into the freezing chamber until it was full. The parameters were set according to the orthogonal experimental design. The freezing operation was carried out according to the optimal freezing time window determined in step two. Each group of experiments was repeated multiple times, and the average value was taken. Response index measurement: Average ice thickness: After freezing, multiple points are measured at different locations on the ice layer using a vernier caliper (accuracy 0.01mm), and the average value is taken as the average ice thickness. Ice crystal salinity: The ice layer was removed, crushed, and dissolved in distilled water. The conductivity was measured using a conductivity meter, and the ice crystal salinity was calculated by combining it with a standard curve. Freezing time: Record the time from the start of cold air to the ice layer reaching a stable state, i.e., the salt content of ice crystals is less than the predetermined value, to verify whether it is within the optimal time window; Ice integrity: After freezing, observe whether the ice layer adheres to the wall of the freezing chamber. It is divided into three levels: "intact (no adhesion, can be removed directly)," "mostly intact (slight adhesion, can be removed with a little external force)," and "incomplete (severe adhesion, cannot be removed completely)." "Intact" and "mostly intact" are considered qualified.

[0046] Step 4: Establish a response surface model and optimize structural parameters; Based on the experimental data from Step 3, construct a response surface surrogate model using quadratic polynomial regression or radial basis functions, with minimizing ice crystal salinity and freezing time meeting a preset window as the main optimization objectives, and ice integrity as the constraint condition; Determine the optimal range of values ​​for each structural parameter through response surface analysis (contour plots, main effects plots, and interaction effects plots); Optimize the response surface model using gradient descent or genetic algorithms to obtain the optimal combination of structural parameters that yields the best overall index; Response surface proxy model construction: Based on the orthogonal experimental data from step three, a response surface surrogate model was constructed using quadratic polynomial regression. Ice crystal salinity (Y1) and freezing time (Y2) were used as response values, and freezing chamber height (A), freezing chamber width (B), cold air inlet velocity (C), cold air temperature (D), and number of partition walls (E) were used as independent variables. The general form of the quadratic polynomial regression model is as follows: ; Where: Y: response value (Y1 is the salt content of ice crystals, Y2 is the freezing time); β0: constant term; β i : coefficient of the linear term; β ii : coefficient of the quadratic term; β ij : Interaction term coefficient; X i X j : Independent variables (A, B, C, D, E); ε: Random error (controlled within ±3%).

[0047] By fitting the experimental data using Design-Expert software, a quadratic polynomial regression equation for the two response values ​​was obtained (example): Ice crystal salinity regression equation (Y1, wt%): Y1=0.215-0.0012A-0.0008B-0.015C-0.0045D-0.008E+0.000005A 2 +0.000004B 2 +0.003C 2 +0.0001D 2 +0.002E 2 -0.00001AB-0.0002AC-0.00005AD-0.0001AE-0.0001BC-0.00004BD-0.00008BE-0.0003CD-0.0002CE-0.0001DE; Frozen time regression equation (Y2, min): Y2=52.3-0.08A-0.05B-2.1C-0.35D-1.2E+0.0003A 2 +0.0002B 2 +0.25C 2 +0.005D 2 +0.3E 2 -0.0004AB-0.01AC-0.002AD-0.005AE-0.003BC-0.001BD-0.004BE-0.03CD-0.02CE-0.01DE.

[0048] Response surface analysis: Response surface plots, contour plots, main effects plots, and interaction effects plots were generated using Design-Expert software to analyze the influence of each independent variable on the response value. Main effect analysis: The cold air temperature (D) has the most significant effect on the ice crystal salinity and freezing time (the coefficient has the largest absolute value). The lower the cold air temperature, the lower the ice crystal salinity and the shorter the freezing time. The second most significant effect is the cold air inlet velocity (C). The higher the velocity, the higher the freezing efficiency. The freezing chamber height (A), freezing chamber width (B), and number of partition walls (E) have relatively small effects, but still need to be optimized. Interaction effect analysis: There is a significant interaction between cold air temperature and cold air velocity. When the cold air temperature is low, increasing the velocity has a more significant effect on shortening the freezing time. There is an interaction between the width of the freezing chamber and the number of partition walls. When the width of the freezing chamber is large, increasing the number of partition walls can improve the cold air distribution and reduce the salt content of ice crystals. Contour map analysis is used to determine the approximate optimal range of values ​​for each parameter.

[0049] Model optimization and determination of optimal parameter combination: Optimization objectives and constraints: The main optimization objectives are: to minimize the ice crystal salinity Y1 and to satisfy the optimal time window for freezing time Y2; Constraints: The ice integrity is taken as complete or nearly complete, and the values ​​of each parameter are within the horizontal range of step three.

[0050] Optimization Algorithm: A genetic algorithm is used for optimization. The core parameters of the genetic algorithm are set as follows: Population size: 50; Number of iterations: 100; Crossover probability: 0.8; Mutation probability: 0.05; Fitness function: (Y2 is the freezing time, T) y (The median value of the optimal time window).

[0051] Optimization results: The optimal combination of structural parameters was obtained by using a genetic algorithm implemented in Matlab software.

[0052] Optimization verification: Repeat the experiment multiple times according to the optimal parameter combination to verify whether the response value meets the requirements.

[0053] Step 5: Determine the final design parameters of the cryogenic desalination device based on the optimization results; use the structural parameters obtained in Step 4 as the basis for manufacturing the cryogenic desalination device, so that the device can perform cryogenic desalination operation according to the optimal freezing time determined in Step 2 during operation.

[0054] Final design parameters determined: The optimal structural parameters obtained in step four are used as the final design parameters of the cryogenic desalination device. At the same time, other auxiliary parameters of the device, such as the material of the freezing chamber, the diameter of the cold air duct, and the thickness of the insulation layer, are determined in combination with the actual manufacturing requirements of the project, so as to determine the final design parameters.

[0055] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A cryogenic desalination device for low-temperature crystallization of high-salt wastewater, comprising a freezing chamber (1) and a cooler (2), wherein the freezing chamber (1) is connected to an inlet on one side and an outlet on the other side, and the freezing chamber (1) is cooled by the cooler (2), characterized in that: The freezer (1) is provided with multiple partition walls (101), which divide the freezer (1) into multiple freezing chambers (102). The multiple freezing chambers (102) are interconnected. Each freezing chamber (102) is provided with a freezing frame (4), and each freezing chamber (102) is provided with a door (3) on one side. The cabinet door (3) is provided with a main locking mechanism and two auxiliary locking mechanisms. When the cabinet door (3) is opened, the auxiliary locking mechanisms can control the freezing frame (4) to pop out or not pop out. The main locking mechanism includes a locking gear (303) and a locking rack (304), the locking rack (304) being able to slide out of the cabinet door (3) and insert into the freezer (1) to form a lock; The auxiliary locking mechanism includes an arc plate (307), which can achieve auxiliary locking, linkage with the freezing frame (4) or non-linkage with the freezing frame (4) by different rotation positions. Both sides of the freezing frame (4) are provided with pushing components, each pushing component corresponds to one of the auxiliary locking mechanisms, and the pushing components are set in the wall of the freezing box (1); The pushing assembly includes a scissor base rod (5), a fixed slide rail (502), and a movable slide rail (503). The angle of the scissor base rod (5) is controlled by adjusting the distance between the movable slide rail (503) and the fixed slide rail (502), thereby pushing out the freezing frame (4).

2. The cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 1, characterized in that: The main locking mechanism also includes a main locking shaft (302), one end of which is fixedly connected to a handwheel (301). The main locking shaft (302) has a thread in the middle and a spline shaft at its lower end. The main locking shaft (302) is threadedly connected to the door (3) in the middle. The spline shaft at the lower end of the main locking shaft (302) is slidably connected to a locking gear (303). The locking gear (303) meshes with a locking rack (304). The locking gear (303) is rotatably connected in the door (3), and the locking rack (304) is slidably connected in the door (3). The handwheel (301) is exposed outside the door (3).

3. The cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 1, characterized in that: The auxiliary locking mechanism also includes an auxiliary locking shaft (306), one end of which is fixedly connected to an auxiliary locking wrench (305). The middle part of the auxiliary locking shaft (306) is provided with a thread, and its lower end is provided with a spline shaft. The middle part of the auxiliary locking shaft (306) is threadedly connected to the cabinet door (3). The spline shaft part at the lower end of the auxiliary locking shaft (306) is slidably connected to an arc plate (307). The arc plate (307) is in contact with a cam (508). The auxiliary locking wrench (305) is exposed outside the cabinet door (3). The arc plate (307) is rotatably connected in the cabinet door (3) and can be partially exposed outside the cabinet door (3) and inserted into the freezer (1) to achieve locking.

4. The cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 3, characterized in that: The bottom surface of the freezing frame (4) is not closed. A sliding side plate (401) is provided on each side of the freezing frame (4). The freezing frame (4) is placed between the two sliding side plates (401). The sliding side plate (401) is in contact with the inner wall of the freezing box (1) and the partition wall (101). A sliding boss (402) is provided on the sliding side plate (401). The sliding boss (402) is slidably connected to the wall of the freezing box (1) or the partition wall (101). The sliding boss (402) is connected to the pushing component.

5. The cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 4, characterized in that: The scissor base rods (5) are provided in multiple ways. Every two scissor base rods (5) are arranged in an X-shape, and their middle parts are hinged to each other to form a scissor rod group. The ends of the scissor base rods (5) of the multiple scissor rod groups are hinged to each other through hinge pins (501) to form scissor rods. One end of one scissor base rod (5) is hinged to a sliding boss (402), and the other end of one scissor base rod (5) is hinged to the inner wall surface of the freezer (1) or the partition wall (101).

6. The cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 5, characterized in that: The fixed slide rail (502) and the movable slide rail (503) are respectively slidably connected to the upper and lower hinge pins (501). The fixed slide rail (502) is fixedly connected to the freezer (1) or the partition wall (101), and the movable slide rail (503) is vertically slidably connected to the freezer (1) or the partition wall (101). A slide rail spring (504) is provided between the fixed slide rail (502) and the movable slide rail (503) to separate the two.

7. The cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 1, characterized in that: The movable slide rail (503) is fixedly connected to the slide rail inclined block (505), the slide rail inclined block (505) is in contact with the push inclined block (506), the push inclined block (506) is fixedly connected to one end of the inclined block push rod (507), the other end of the inclined block push rod (507) is in contact with the cam (508), the slide rail inclined block (505), the push inclined block (506) and the inclined block push rod (507) are slidably connected in the freezer (1) or the partition wall (101), and the push inclined block (506) is provided with a spring for resetting.

8. The cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 7, characterized in that: The cam (508) is slidably connected to the cam spline shaft (509), the cam spline shaft (509) is fixedly connected to the door (3), the door (3) is hinged to the freezer (1), the hinge position of the cam spline shaft (509) and the door (3) is coaxially set, and a cam spring (510) is provided between the cam (508) and the door (3), the cam spring (510) is surrounded around the cam spline shaft (509).

9. The design method of a cryogenic desalination device for low-temperature crystallization of high-salinity wastewater according to claim 1, characterized in that, The steps are as follows: Step 1: Determine the solute migration law and crystallization front advancement speed of brine during the freeze-crystallization process; obtain the ice crystal growth rate and salt enrichment concentration distribution in the unfrozen area of ​​brine under different initial salt concentrations and different freezing temperatures through experiments, establish the quantitative relationship between solute partition coefficient and freezing speed, and determine the advancement speed v(t) of the crystallization front along the freezing direction. Step 2: Establish the optimal relationship between freezing time and ice thickness; based on the crystallization propagation rate v(t) obtained in Step 1, and with the target ice purity as a constraint, determine the optimal freezing time window t through theoretical calculations or semi-empirical models. opt This makes the ice thickness H within that time window... ice To reach maximum without significant salt inclusions or dendrite encapsulation; Step 3: Design an orthogonal experimental design and conduct physical experiments; select key structural and operational parameters affecting the cryogenic desalination effect as design variables, including: freezing chamber height, freezing chamber width, cold air inlet velocity, cold air temperature, and number of partition walls; select multiple levels for each variable and arrange the experiments using an orthogonal array; conduct cryogenic desalination experiments on a physical prototype or small experimental platform, and measure the response indicators: average ice layer thickness, ice crystal salinity, freezing time, and ice integrity; record the results of each group of experiments; Step 4: Establish a response surface model and optimize structural parameters; Based on the experimental data from Step 3, construct a response surface surrogate model using quadratic polynomial regression or radial basis functions, with minimizing ice crystal salinity and freezing time within a preset window as the main optimization objectives, and ice integrity as the constraint; Determine the optimal range of values ​​for each structural parameter through response surface analysis; Optimize the response surface model using gradient descent or genetic algorithms to obtain the optimal combination of structural parameters that yields the best comprehensive index; Step 5: Determine the final design parameters of the cryogenic desalination device based on the optimization results; use the structural parameters obtained in Step 4 as the basis for manufacturing the cryogenic desalination device, so that the device can perform cryogenic desalination operation according to the optimal freezing time determined in Step 2 during operation.

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