Falling film crystallization method, falling film crystallizer and temperature control method

Abstract

The present invention relates to a falling film crystallization method, a falling film crystallizer and a temperature control method. The falling film crystallization method sequentially comprises the steps of feeding, crystallization and melting, and further comprises an induced crystallization step after the step of feeding and before the step of crystallization, wherein the induced crystallization comprises: feeding a heat-conducting medium into the inner upper side of a falling film crystallizer, so as to make a material to be treated to form a crystal nucleus on the upper part of the falling film crystallizer. By using the method of the present invention to perform falling film crystallization, crystallization nuclei in feed liquid are easy to form; the uniformity of the crystallization speed can be improved, a speed difference during the crystal growth process can be avoided, the uniformity of the sizes and morphologies of crystals can be improved, and the quality and purity of a product can be improved; the crystallization process can be accelerated, and the time for the crystallization process can be shortened; and the energy consumption during the crystallization process can be reduced.

Description

Falling film crystallization method, falling film crystallizer and temperature control method Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and in particular relates to a falling film crystallization method, a falling film crystallizer and a temperature control method. Background Art

[0002] A falling film crystallizer is a device used in the falling film crystallization process. It uses a cooling process (typically, as the liquid flows downward over a solid wall, it exchanges heat with a heat-conducting medium flowing in a film-like manner on the other side of the wall, lowering the liquid temperature) to crystallize the solute in the liquid. Falling film crystallizers are widely used in processes such as the purification of homologues and isomers of organic compounds with similar boiling points, the separation and purification of heat-sensitive substances, and the preparation of high-purity and ultra-high-purity products.

[0003] In the related art, traditional falling film crystallizers usually use a single cooler or cooler to reduce the temperature of the solution and promote the crystallization of the solute in the feed solution. However, the use of traditional falling film crystallizers for crystallization has the following defects: the formation of crystal nuclei is affected by many factors such as impurities, supersaturation and flow state in the solution. These factors may make it difficult for crystal nuclei to form, thereby delaying the start of crystallization or making the crystallization efficiency low, requiring a larger degree of supercooling, resulting in a long crystallization process and high energy consumption. Secondly, excessive supercooling will cause rapid crystallization after the generation of seed crystals, resulting in poor crystallization purification effect and even clogging of the equipment. Furthermore, when using traditional falling film crystallizers for processing, the crystallization rate may vary at different stages. The reason is that the crystal nucleus formation stage in the early stage of crystallization requires a larger degree of supercooling and driving force than the crystal nucleus growth stage in the later stage of crystallization, resulting in uneven crystallization rates at different stages of the crystallization process, further leading to uneven crystal size and morphology, and reducing the quality and purity of the product. In addition, traditional falling film crystallizers usually use distributors to distribute the cold and hot media to the outer wall of the crystallizer, so that the cold and hot media flow downward in a film-like state along the outer wall of the crystallization tube. However, since the crystallization tube is usually a circular tube, the cold and hot media fluids are more likely to aggregate during the downward longitudinal flow under the action of gravity, which can easily cause uneven film formation, thereby affecting the heat exchange effect of the cold and hot media, increasing the time consumption of the crystallization process, and increasing the demand for cold and hot media.

[0004] Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a falling film crystallization method, a falling film crystallizer and a temperature control method.

[0006] In the first aspect, the present invention provides a falling film crystallization method, which includes feeding, crystallization and melting steps in sequence. After the feeding and before the crystallization, it also includes an induced crystallization step. The induced crystallization includes: feeding a heat-conducting medium into the upper side of the falling film crystallizer to allow the material to be processed to form crystal nuclei on the upper part of the falling film crystallizer.

[0007] In some embodiments, the inlet temperature of the heat transfer medium is the actual crystallization start temperature of the target product.

[0008] In some embodiments, after the crystal nuclei are formed, the cooling rate of the heat conducting medium is controlled to be 0.3-0.5° C. / min.

[0009] In some embodiments, after crystallization and before melting, the falling film crystallization method further comprises a sweating step.

[0010] In some embodiments, the falling film crystallization method further includes: discharging the heat transfer medium after heat exchange from the falling film crystallizer.

[0011] In some embodiments, the material to be treated includes fluoroethylene carbonate solution, acrylic acid solution or 3,5-dimethylphenol.

[0012] In some embodiments, the present invention also provides a falling film crystallizer used in the falling film crystallization method as described above, the falling film crystallizer includes a shell, the top and bottom of the shell are respectively provided with a material inlet and a material outlet, a plurality of vertically arranged crystallization tubes are provided inside the shell, an induced crystallization zone and a crystallization zone are sequentially provided between the material inlet and the material outlet, the induced crystallization zone and the crystallization zone are respectively provided with a heat transfer medium inlet, a distribution plate, a heat transfer medium outlet and a bottom plate from top to bottom, the distribution plate is arranged in a horizontal direction, a guide is fixedly provided on the distribution plate, the guide is sleeved on the outside of the crystallization tube, a top plate arranged in a horizontal direction is further provided between the induced crystallization zone and the material inlet, the top plate and the bottom plate are both provided with a plurality of through holes corresponding one to one to the crystallization tubes, and the top plate and the bottom plate are sleeved on the outside of the crystallization tube through the through holes.

[0013] In some embodiments of the present application, a number of vertically arranged crystallization tubes are provided inside the shell, and the distribution plate is fixedly provided with deflectors corresponding one-to-one to the crystallization tubes, all of the deflectors are sleeved on the outside of the corresponding crystallization tubes, and the top plate is opened with through holes corresponding one-to-one to the crystallization tubes, and the top plate is sleeved on the outside of all the crystallization tubes through the through holes.

[0014] In some embodiments of the present application, the crystallization zone is provided with a plurality of distribution plates arranged in a horizontal direction from top to bottom.

[0015] In some embodiments of the present application, the guide is annular, and is provided with a guide inlet, a guide outlet and a guide channel located between the guide inlet and the guide outlet, the guide channel is tangentially connected to the guide inlet, the guide inlet is located above the guide outlet, and the guide outlet is fixed on the distribution plate.

[0016] In some embodiments of the present application, the guide channel is tangentially connected to the guide outlet.

[0017] In some embodiments of the present application, a distributor is provided inside the material inlet.

[0018] In some embodiments of the present application, the width of the diversion inlet is 2-8 mm.

[0019] In some embodiments of the present application, the height of the diversion inlet is 2-8 mm.

[0020] In some embodiments of the present application, the guide channel is S-shaped.

[0021] In some embodiments of the present application, a plurality of film distributors are further provided in the shell, and the film distributors are located between the distributor and the crystallization tubes in the induced crystallization zone, and the film distributors correspond to the crystallization tubes one by one and are connected.

[0022] In some embodiments of the present application, the present invention further provides a temperature control method for the falling film crystallizer as described above, wherein the temperature control method is used to control the temperature of the cooling medium in the cooling medium pipelines connected to the cooling medium inlets at the upper and middle portions of the falling film crystallizer, and the temperature control method comprises:

[0023] Obtaining a crystallization state of the material to be processed in the falling film crystallizer, wherein the crystallization state includes the formation of crystal nuclei;

[0024] If the crystallization state is that crystal nuclei have been formed, controlling the first cooling medium to increase in temperature at a first preset rate based on a first inlet temperature, and controlling the second cooling medium to decrease in temperature at a second preset rate based on a second inlet temperature, wherein the first inlet temperature is lower than the second inlet temperature, the first cooling medium and the second cooling medium are cooling media in cooling medium pipes connected to the upper and middle cooling medium inlets of the falling film crystallizer, respectively, and the first inlet temperature and the second inlet temperature are temperatures of the first cooling medium and the second cooling medium when they enter the upper and middle cooling medium inlets of the falling film crystallizer, respectively;

[0025] Acquire a first real-time temperature of the first cooling medium and a second real-time temperature of the second cooling medium;

[0026] If the first real-time temperature is equal to the second real-time temperature, the first cooling medium and the second cooling medium are controlled to cool down at a third preset rate until a preset temperature threshold is reached, the third preset rate is greater than the first preset rate and the second preset rate, and the preset temperature threshold is less than the first inlet temperature.

[0027] In some embodiments of the present application, the first inlet temperature is the same as the actual crystallization start temperature of the target product.

[0028] In some embodiments of the present application, the second inlet temperature is the same as the theoretical crystallization start temperature of the target product.

[0029] In some embodiments of the present application, the first preset rate is 0.2-0.3°C / min.

[0030] In some embodiments of the present application, the second preset rate is 0.1-0.18°C / min.

[0031] In some embodiments of the present application, the third preset rate is 0.3-0.5°C / min.

[0032] In some embodiments of the present application, the present invention further provides a cooling medium temperature control system, the temperature control system being used to control the temperature of the cooling medium in the cooling medium pipelines connected to the cooling medium inlets at the upper and middle portions of the falling film crystallizer, the temperature control system comprising:

[0033] a crystallization state acquisition module configured to obtain the crystallization state of the material to be processed in the falling film crystallizer, wherein the crystallization state includes the formation of crystal nuclei;

[0034] a first control module, if the crystallization state is that crystal nuclei have been formed, being configured to control the first cooling medium to increase in temperature at a first preset rate based on a first inlet temperature, and to control the second cooling medium to decrease in temperature at a second preset rate based on a second inlet temperature, wherein the first inlet temperature is lower than the second inlet temperature, the first cooling medium and the second cooling medium are cooling media in cooling medium pipes connected to the upper and middle cooling medium inlets of the falling film crystallizer, respectively, and the first inlet temperature and the second inlet temperature are temperatures of the first cooling medium and the second cooling medium when they enter the upper and middle cooling medium inlets of the falling film crystallizer, respectively;

[0035] A real-time temperature acquisition module is configured to acquire a first real-time temperature of the first cooling medium and a second real-time temperature of the second cooling medium;

[0036] The second control module is configured to control the first cooling medium and the second cooling medium to cool down at a third preset rate until a preset temperature threshold if the first real-time temperature is equal to the second real-time temperature, the third preset rate being greater than the first preset rate and the second preset rate, and the preset temperature threshold being less than the first inlet temperature.

[0037] In some embodiments of the present application, the present invention further provides an electronic device, comprising:

[0038] one or more processors;

[0039] The storage device is used to store one or more programs, and when the one or more programs are executed by the one or more processors, the electronic device implements the temperature control method as described above.

[0040] In some embodiments of the present application, the present invention further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor of a computer, the computer is caused to execute the temperature control method as described above.

[0041] As described above, the falling film crystallization method and falling film crystallizer of the present invention have the following beneficial effects:

[0042] By adopting the method of the present invention for falling film crystallization, crystal nuclei in the feed solution are easily formed; the uniformity of the crystallization rate can be improved, speed differences during the crystal growth process can be avoided, the uniformity of the crystal size and morphology can be improved, and the quality and purity of the product can be improved; the crystallization process can be accelerated, the crystallization process time can be shortened, and the energy consumption of the crystallization process can be reduced.

[0043] The present application obtains the crystallization state of the material to be processed in the falling film crystallizer. If the crystallization state is that a crystal nucleus has been formed, the first cooling medium is controlled to increase the temperature at a first preset rate based on the first inlet temperature, and the second cooling medium is controlled to decrease the temperature at a second preset rate based on the second inlet temperature, to obtain the first real-time temperature of the first cooling medium and the second real-time temperature of the second cooling medium. If the first real-time temperature is equal to the second real-time temperature, the first cooling medium and the second cooling medium are controlled to decrease the temperature at a third preset rate until the preset temperature threshold, that is, the pre-crystallization stage is first heated and then cooled. On the one hand, it can slightly dissolve the large-volume crystal nucleus, which is the same as the sweating effect, which is equivalent to the first sweating of the crystal nucleus. This is beneficial to remove impurities in the large-volume crystal nucleus, thereby improving the purity of the crystal nucleus. Since the pre-crystallization stage has initially formed a crystal nucleus, which is a rapid nucleation, a small amount of impurities are inevitably wrapped in the crystal nucleus. Slightly increasing the temperature can sweat out part of these impurities in the crystal nucleus, preventing the impurities wrapped in the nucleation stage from being too deeply wrapped in the later crystal growth stage and difficult to be discharged in the subsequent sweating process. On the other hand, under the same slightly elevated temperature conditions, large nuclei partially melt, with their volume remaining virtually unchanged. Only the edge spikes melt, achieving consistent morphology across different nuclei. Under the same slightly elevated temperature conditions, small nuclei completely melt, preventing the precipitation of new nuclei. At this point, the material consists almost exclusively of nuclei of uniform size. Consequently, crystals subsequently grown from these nuclei are uniform in size, improving product quality and purity. Furthermore, by fully utilizing the pre-crystallization stage, the surface area of ​​the crystallization stage is increased, further improving utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] FIG1 is a schematic structural diagram of a falling film crystallizer of Example 1;

[0045] FIG2 is an assembly diagram of the distribution plate, guide plate and crystallization tube in Example 1;

[0046] FIG3 is an expanded view of the deflector in Example 1;

[0047] FIG4 is a schematic structural diagram of a falling film crystallizer of Example 2;

[0048] FIG5 is a flow chart of a temperature control method shown in Example 6;

[0049] FIG6 is a block diagram of a temperature control system shown in Example 7;

[0050] FIG7 shows a schematic structural diagram of a computer system suitable for implementing the electronic device of the eighth embodiment.

[0051] Explanation of the reference numerals: 11-material inlet, 111-distributor, 12-material outlet, 13-crystallization tube, 131-film distributor, 14-top plate, 15-heat transfer medium inlet, 16-distribution plate, 161-flow guide, 1611-flow guide inlet, 1612-flow guide outlet, 1613-flow guide channel, 17-heat transfer medium outlet, 18-bottom plate. DETAILED DESCRIPTION

[0052] The present invention is further described below through specific examples. However, it should be pointed out that the specific material ratios, process conditions and results described in the embodiments of the present invention are only used to illustrate the present invention and cannot be used to limit the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

[0053] It should be noted that all directional indications (such as up, down, inside, and outside) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0054] In this utility model, unless otherwise specified or limited, the term "connected" and the like should be understood in a broad sense. For example, it can mean direct connection or indirect connection through an intermediate medium, internal communication between two components, or interaction between two components, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0055] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this utility model.

[0056] The present invention provides a falling film crystallization method, which sequentially comprises the steps of feeding, crystallization, sweating and melting. After feeding and before crystallization, it also comprises an induced crystallization step, which comprises: feeding a heat-conducting medium into the upper side of the falling film crystallizer so that the material to be processed forms crystal nuclei on the upper part of the falling film crystallizer, the inlet temperature of the heat-conducting medium is the actual starting crystallization temperature of the target product, and after the crystal nuclei are formed, the cooling rate of the heat-conducting medium is controlled to be 0.3-0.5°C / min.

[0057] The heat transfer medium after heat exchange is discharged from the falling film crystallizer.

[0058] The materials to be treated include fluoroethylene carbonate liquid, acrylic acid liquid or 3,5-dimethylphenol.

[0059] In some embodiments, the present invention also provides a falling film crystallizer used in the falling film crystallization method as described above, the falling film crystallizer includes a shell, the top and bottom of the shell are respectively provided with a material inlet and a material outlet, a plurality of vertically arranged crystallization tubes are provided inside the shell, an induced crystallization zone and a crystallization zone are sequentially arranged between the material inlet and the material outlet, and the induced crystallization zone and the crystallization zone are sequentially provided with a heat transfer medium inlet, a distribution plate, a heat transfer medium outlet and a bottom plate from top to bottom, the distribution plate is arranged in a horizontal direction, and a guide is fixedly provided on the distribution plate, and the guide is sleeved on the outside of the crystallization tube, and a top plate arranged in a horizontal direction is further provided between the induced crystallization zone and the material inlet, the top plate and the bottom plate are both provided with through holes corresponding one to one to the crystallization tubes, and the top plate and the bottom plate are sleeved on the outside of the crystallization tube through the through holes, a distributor is provided inside the material inlet, and a plurality of film distributors are further provided in the shell, the film distributor is located between the distributor and the crystallization tube, and the film distributor corresponds one to one to and is connected to the crystallization tube.

[0060] In some embodiments of the present application, the crystallization region is provided with a plurality of distribution plates arranged in a horizontal direction from top to bottom.

[0061] In some embodiments of the present application, the deflector is annular, and the deflector is provided with a deflector inlet, a deflector outlet and a deflector channel located between the deflector inlet and the deflector outlet. The deflector channel is tangentially connected to the deflector inlet and the deflector outlet. The deflector inlet is located above the deflector outlet, the width of the deflector inlet is 2-8mm, the height of the deflector inlet is 2-8mm, and the deflector outlet is fixedly set on the distribution plate, and the deflector channel is S-shaped.

[0062] The present invention will be described in detail below by way of specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention fall within the scope of protection of the present invention.

[0063] Example 1

[0064] Please refer to FIG1 , which is a schematic structural diagram of the falling film crystallizer of this embodiment.

[0065] As shown in Figure 1, the falling film crystallizer comprises a housing with a material inlet 11 and a material outlet 12 disposed at the top and bottom of the housing, respectively. A plurality of vertically arranged crystallization tubes 13 are disposed within the housing, each with a feed port and a discharge port disposed at the top and bottom, respectively. An induced crystallization zone and a crystallization zone are sequentially disposed between the material inlet 11 and the material outlet 12. A distributor 111 is disposed within the material inlet 11. Distributor 111 is conventional and will not be described further herein. The material inlet 11 is connected to a distribution pipe network equipped with a plurality of liquid dispensing heads corresponding one to each of the crystallization tubes 13.

[0066] 1 , a film distributor 131 is provided in the housing. The film distributor 131 is located between the liquid separation head and the crystallization tube 13 . The film distributor 131 corresponds to and is connected to the crystallization tube 13 . The film distributor 131 is prior art and will not be described in detail here.

[0067] Please continue to refer to Figure 1. A top plate 14 is provided horizontally between the induced crystallization zone and the material inlet 11. The top plate 14 is used to fix the crystallization tube 13. The top plate 14 has a plurality of through holes, all of which correspond to the crystallization tubes 13 one by one. The diameter of the through holes is slightly larger than the outer diameter of the crystallization tube 13. The top plate 14 is sleeved on the outside of the crystallization tube 13 through the through holes so that the crystallization tube 13 is fixed to the inner wall of the shell through the top plate 14.

[0068] Continuing with Figure 1, the induced crystallization zone is used to initially cool the material being processed, allowing solutes in the material to crystallize and form nuclei on the walls of the crystallization tubes 13 within the induced crystallization zone. From top to bottom, the induced crystallization zone is equipped with a heat transfer medium inlet 15, a distribution plate 16, a heat transfer medium outlet 17, and a bottom plate 18.

[0069] Please continue to refer to Figure 1. The heat-conducting medium inlet 15 of the induced crystallization zone is used as the inlet for introducing the heat-conducting medium into the induced crystallization zone of the falling film crystallizer, and the heat-conducting medium outlet 17 of the induced crystallization zone is used as the outlet for discharging the heat-conducting medium after heat exchange in the induced crystallization zone out of the falling film crystallizer.

[0070] Please continue to refer to Figures 1 and 2. The distribution plate 16 of the induced crystallization zone is arranged in the horizontal direction. A number of guides 161 are fixedly provided on the distribution plate 16. All guides 161 correspond to the crystallization tubes 13 one by one. Specifically, all guides 161 are sleeved on the outside of the corresponding crystallization tubes 13.

[0071] Please continue to refer to Figures 2 and 3. The guide 161 in the induced crystallization zone is annular, and a number of guide inlets 1611, guide outlets 1612 and guide channels 1613 located between the guide inlets 1611 and the guide outlets 1612 are arranged along the circumference of the guide 161. The guide channels 1613 are tangentially connected to the corresponding guide inlets 1611 and the corresponding guide outlets 1612. The guide inlet 1611 is located above the guide outlet 1612, and the guide outlet 1612 is fixed on the distribution plate 16 through a hole opened on the distribution plate 16. The width of the guide inlet 1611 is 2-8 mm, the height of the guide inlet 1611 is 2-8 mm, and the guide channel 1613 is S-shaped.

[0072] Specifically, by tangentially connecting the flow channel 1613 to the flow inlet 1611, the tangential velocity of the heat transfer medium within the flow channel 1613 can be increased, thereby increasing the degree of tangential swirl of the heat transfer medium, reducing the longitudinal cohesive force of the fluid, and thereby improving the uniformity of the heat transfer medium's film distribution on the outer wall of the crystallization tube 13. By tangentially connecting the flow channel 1613 to the flow outlet 1612, the degree of tangential swirl of the heat transfer medium as it flows out of the flow channel 1613 can be increased, reducing the longitudinal cohesive force of the heat transfer medium, allowing the heat transfer medium to form a swirling flow state on the outer wall of the crystallization tube 13, enhancing the uniformity of the heat transfer medium's film distribution and forming a uniform thin film on the outer wall of the crystallization tube 13. By arranging the flow channel 1613 in an S-shape, the heat transfer medium can be guided downward by the guide surface of the flow channel 1613 in a swirling manner, further improving the uniformity of the heat transfer medium's film distribution and further improving the crystallization effect. By circumferentially arranging a plurality of guide inlets 1611, guide outlets 1612 and guide channels 1613 located between the guide inlets and the guide outlets on the guide 161, the cooling medium can be further diverted so that the diverted cooling medium can better exchange heat with the material to be processed, thereby improving the uniformity of crystallization.

[0073] Please continue to refer to Figure 1. The bottom plate 18 of the induced crystallization zone is used to collect the heat-conducting medium after heat exchange. The bottom plate 18 is located below the heat-conducting medium outlet 17. The bottom plate 18 is provided with a plurality of through holes, all of which correspond one to one with the crystallization tubes 13. The diameter of the through holes is slightly larger than the outer diameter of the crystallization tubes 13. The bottom plate 18 is sleeved on the outside of the crystallization tubes 13 through the through holes, so that the crystallization tubes 13 are fixed to the inner wall of the shell through the bottom plate 18.

[0074] The principle of this embodiment is as follows: by adding an induced crystallization zone between the material inlet 11 and the crystallization zone, and arranging a heat-conducting medium inlet 15 and a heat-conducting medium outlet 17 in the induced crystallization zone, a heat-conducting medium can be introduced into the falling film crystallizer through the heat-conducting medium inlet 15 to pre-cool the feed liquid, so that the crystallization core in the feed liquid is easy to form; secondly, the pre-cooling treatment of the crystallization part in the induced crystallization zone can improve the uniformity of the crystallization rate, avoid the speed difference in the crystal growth process, improve the uniformity of the crystal size and morphology, and improve the quality and purity of the product; furthermore, it helps to improve the crystallization efficiency, accelerate the crystallization process, and shorten the crystallization process time; in addition, the effect of the pre-cooling zone reduces the supercooling of the material crystallization, which can reduce the energy consumption of the crystallization process.

[0075] Continuing to refer to Figure 1, the crystallization zone is used to further cool the material so that the crystal nuclei initially formed in the induction crystallization zone continue to grow. The crystallization zone is provided with a heat transfer medium inlet 15, a distribution plate 16, a heat transfer medium outlet 17 and a bottom plate 18 in order from top to bottom.

[0076] Please continue to refer to Figure 1. The heat-conducting medium inlet 15 of the crystallization zone is used as an inlet for introducing the heat-conducting medium into the crystallization zone of the falling film crystallizer, and the heat-conducting medium outlet 17 of the crystallization zone is used as an outlet for discharging the heat-conducting medium after heat exchange in the crystallization zone out of the falling film crystallizer.

[0077] Please continue to refer to Figures 1 and 2. The distribution plate 16 of the crystallization zone is arranged in the horizontal direction. A plurality of guides 161 are fixedly provided on the distribution plate 16. All guides 161 correspond to the crystallization tubes 13 one by one. Specifically, all guides 161 are sleeved on the outside of the corresponding crystallization tubes 13.

[0078] Please continue to refer to Figures 2 and 3. The guide 161 in the crystallization zone is annular. The guide 161 is provided with a guide inlet 1611, a guide outlet 1612 and a guide channel 1613 located between the guide inlet 1611 and the guide outlet 1612. The guide channel 1613 is tangentially connected to the guide inlet 1611 and the guide outlet 1612. The guide inlet 1611 is located above the guide outlet 1612, and the guide outlet 1612 is fixed on the distribution plate 16 through a hole opened on the distribution plate 16. The width of the guide inlet 1611 is 2-8 mm, the height of the guide inlet 1611 is 2-8 mm, and the guide channel 1613 is S-shaped.

[0079] Specifically, by tangentially connecting the flow channel 1613 to the flow inlet 1611, the tangential velocity of the heat transfer medium within the flow channel 1613 can be increased, thereby increasing the degree of tangential swirl of the heat transfer medium, reducing the longitudinal cohesive force of the fluid, and thereby improving the uniformity of the heat transfer medium's film distribution on the outer wall of the crystallization tube 13. By tangentially connecting the flow channel 1613 to the flow outlet 1612, the degree of tangential swirl of the heat transfer medium as it flows out of the flow channel 1613 can be increased, reducing the longitudinal cohesive force of the heat transfer medium, allowing the heat transfer medium to form a swirling flow state on the outer wall of the crystallization tube 13, enhancing the uniformity of the heat transfer medium's film distribution and forming a uniform thin film on the outer wall of the crystallization tube 13. By arranging the flow channel 1613 in an S-shape, the heat transfer medium can be guided downward by the guide surface of the flow channel 1613 in a swirling manner, further improving the uniformity of the heat transfer medium's film distribution and further improving the crystallization effect.

[0080] Continuing with FIG1 , the bottom plate 18 of the crystallization zone is used to collect the heat-conducting medium in the crystallization zone after heat exchange. The bottom plate 18 is located below the heat-conducting medium outlet 17 and is provided with a plurality of through holes. All of the through holes correspond one to one with the crystallization tubes 13, and the diameter of the through holes is slightly larger than the outer diameter of the crystallization tubes 13. The bottom plate 18 is sleeved on the outside of the crystallization tubes 13 through the through holes, so that the crystallization tubes 13 are fixed to the inner wall of the shell through the bottom plate 18.

[0081] The principle of this embodiment is as follows: by adding an induced crystallization zone, the material in the crystallization tube 13 can form crystals in the induced crystallization zone, which can serve as crystal nuclei for crystallization in the crystallization zone, thereby reducing the time for forming crystal nuclei in the crystallization zone. At the same time, the crystallization zone no longer requires a large degree of supercooling for crystallization. On the one hand, the energy consumption required for crystallization is saved, and on the other hand, the crystallization process speed is made relatively uniform, thereby improving the uniformity of crystal size and morphology, and improving the quality and purity of the product.

[0082] Example 2

[0083] Please refer to FIG4 , which is a schematic structural diagram of the falling film crystallizer of this embodiment.

[0084] As shown in FIG4 , the difference between this embodiment and embodiment 1 is that a plurality of distribution plates 16 arranged in a horizontal direction are provided in the crystallization region from top to bottom.

[0085] Specifically, this embodiment can redistribute the heat transfer medium by providing a number of distribution plates 16 arranged horizontally from top to bottom in the crystallization zone, thereby preventing the heat transfer medium from gathering and flowing outside the crystallization tube due to the excessive length of the crystallization tube, thereby causing uneven crystallization.

[0086] Example 3

[0087] The falling film crystallizer of Example 2 was used to perform falling film crystallization on a fluoroethylene carbonate solution having a purity of 99% and a temperature of 30° C. The process was as follows:

[0088] Fluoroethylene carbonate liquid with a purity of 99% and a temperature of 30°C is fed into the falling film crystallizer through the material inlet. Under the action of the distributor 111 and the film distributor 131, the fluoroethylene carbonate liquid enters the crystallization tube 13 and is distributed in the form of a film on the inner wall of the crystallization tube 13, and flows in the form of a film on the inner wall of the crystallization tube 13.

[0089] A heat-conducting medium of 30% ethylene glycol aqueous solution with an inlet temperature of 12°C and a volume ratio of 30% is fed into the induced crystallization zone through the heat-conducting medium inlet 15 (i.e., the temperature of the ethylene glycol aqueous solution when it enters the heat-conducting medium inlet 15 is 12°C). The heat-conducting medium that has not entered the falling film crystallizer is quickly cooled down by the cooling mechanism outside the falling film crystallizer. When the heat-conducting medium ethylene glycol aqueous solution in the induced crystallization zone accumulates to a certain amount, it enters the diversion channel 1613 from the diversion inlet 1611. Since the guide channel 1613 is tangentially connected to the guide inlet 1611, the tangential velocity of the heat-conducting medium in the guide channel 1613 is increased, thereby increasing the tangential vortex degree of the heat-conducting medium ethylene glycol aqueous solution, reducing the longitudinal aggregation force of the fluid, and thereby increasing the uniformity of the heat-conducting medium ethylene glycol aqueous solution film on the outer wall of the crystallization tube 13; since the guide channel 1613 is S-shaped, the heat-conducting medium ethylene glycol aqueous solution can be guided by the guide surface of the guide channel 1613 to flow downward in a vortex manner, further increasing the uniformity of the heat-conducting medium ethylene glycol aqueous solution film, and thereby further improving the crystallization effect. Because the diversion channel 1613 is tangentially connected to the diversion outlet 1612, the degree of tangential swirl of the ethylene glycol aqueous solution as the heat-conducting medium flows out of the diversion channel 1613 is increased, reducing the longitudinal cohesive force of the ethylene glycol aqueous solution, causing the ethylene glycol aqueous solution to form a swirling flow on the outer wall of the crystallization tube 13. This enhances the uniformity of the ethylene glycol aqueous solution film distribution, allowing the ethylene glycol aqueous solution to form a uniform thin film on the outer wall of the crystallization tube 13. During this process, the ethylene glycol aqueous solution gradually absorbs heat from the crystallization tube, lowering the temperature of the fluoroethylene carbonate slurry on the inner wall of the crystallization tube 13. When the temperature of the fluoroethylene carbonate slurry reaches 12°C (the actual crystallization starting temperature of the target product), crystal nuclei begin to form in the induced crystallization zone. Simultaneously, the ethylene glycol aqueous solution flows along the outer wall of the crystallization tube 13 in a film-like manner and is collected on the bottom plate 18 of the induced crystallization zone. The ethylene glycol aqueous solution, after heat exchange, can be discharged through the heat-conducting medium outlet 17 of the induced crystallization zone.

[0090] Control the cooling rate of the heat transfer medium to 0.3°C / min until the temperature drops to -1°C;

[0091] Subsequently, a 30% by volume ethylene glycol aqueous solution heat transfer medium with an inlet temperature of 16°C is fed into the crystallization zone through the heat transfer medium inlet 15. The heat transfer medium ethylene glycol aqueous solution is distributed on the outer wall of the crystallization tube 13 by the flow guide 161 on the distribution plate 16, so that the heat transfer medium ethylene glycol aqueous solution forms a uniform thin film on the outer wall of the crystallization tube 13. The heat transfer medium ethylene glycol aqueous solution exchanges heat with the material in the crystallization tube 13 in the crystallization zone, and part of the material crystallizes on the inner wall of the crystallization tube 13.

[0092] The uncrystallized material can be discharged from the material outlet 12 through the discharge port;

[0093] The tube was heated to 30°C to completely melt the crystals on the tube wall. Samples were taken for analysis to test the purity of the melted product. The various production parameters during the production process were recorded. The results are shown in Table 1.

[0094] Among them, the purity is tested in accordance with "GB / T 4790-2014 Fluoroethylene Carbonate".

[0095] Example 4

[0096] The difference between this embodiment and embodiment 3 is that:

[0097] The material to be processed is acrylic acid liquid with a temperature of 21°C and a purity of 99.5wt%. The heat transfer medium is a 45% by volume ethylene glycol aqueous solution. The inlet temperature of the heat transfer medium in the induced crystallization section is 3°C, and the inlet temperature of the heat transfer medium in the crystallization section is 8°C.

[0098] After crystal nuclei appear on the wall of the crystallization tube in the induced crystallization zone, the cooling rate of the heat transfer medium is controlled at 0.3°C / min until the temperature drops to -12°C.

[0099] The temperature was raised to 21°C to completely melt the crystals on the wall of the crystallization tube. Samples were taken for analysis to test the purity of the melted product. The various production parameters during the production process were recorded. The results are shown in Table 1.

[0100] The purity is tested in accordance with GB / T 17529.1-2008 Industrial Propylene Esters and Esters Part 1: Industrial Acrylic Acid.

[0101] Example 5

[0102] The difference between this embodiment and embodiment 3 is that:

[0103] The material to be processed is a 3,5-dimethylphenol liquid with a temperature of 70°C and a purity of 92wt%. The heat transfer medium is water. The inlet temperature of the heat transfer medium in the induced crystallization section is 52°C, and the inlet temperature of the heat transfer medium in the crystallization section is 56°C.

[0104] After crystal nuclei appear on the wall of the crystallization tube in the induced crystallization zone, the cooling rate of the heat transfer medium is controlled at 0.3°C / min until the temperature drops to 40°C.

[0105] The temperature was raised to 70°C to completely melt the crystals on the wall of the crystallization tube. Samples were taken for analysis to test the purity of the melted product. The various production parameters during the production process were recorded. The results are shown in Table 1.

[0106] The purity was tested by capillary chromatography.

[0107] Comparative Example 1

[0108] The difference between this comparative example and Example 3 is that the falling film crystallizer is not provided with an induced crystallization zone, and the inlet temperature of the heat transfer medium is 12°C.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 4 is that the falling film crystallizer is not provided with an induced crystallization zone, and the inlet temperature of the heat transfer medium is 52°C.

[0111] Comparative Example 3

[0112] The difference between this comparative example and Example 5 is that the falling film crystallizer is not provided with an induced crystallization zone, and the inlet temperature of the heat transfer medium is 12°C.

[0113] Table 1 Test results

[0114] Note: The time from the start of crystal nucleation is the time between the start of the addition of the heat transfer medium and the start of the appearance of crystal nuclei on the tube wall. The total crystallization time is the time between the start of the addition of the heat transfer medium and the start of perspiration.

[0115] As can be seen from Table 1, compared with Comparative Examples 1-3, the time to start forming crystal nuclei and the total time of the crystallization process in Examples 3-5 are shortened, and the product purity is increased. This result shows that the present invention accelerates the crystallization process and shortens the crystallization time by adding an induced crystallization zone, which can reduce the energy consumption of the crystallization process and improve product quality.

[0116] Example 6

[0117] Figure 5 is a flow chart of a temperature control method for a falling film crystallizer shown in an exemplary embodiment of the present application, wherein the temperature control method for a falling film crystallizer is used to control the temperature of the cooling medium in the cooling medium pipeline connected to the upper and middle cooling medium inlets of the falling film crystallizer (i.e., the cooling medium inlet of the pre-crystallization section and the cooling medium inlet of the crystallization section) in Figure 1.

[0118] As shown in FIG5 , in an exemplary embodiment of the present application, the temperature control method of the falling film crystallizer includes at least steps S410 to S440, which are described in detail as follows:

[0119] Step S410. Obtaining the crystallization state of the material to be processed in the falling film crystallizer;

[0120] It should be noted that the crystalline state includes the state where crystal nuclei have been formed;

[0121] For example, the material to be treated may be fluoroethylene carbonate solution, acrylic acid solution or 3,5-dimethylphenol;

[0122] Step S420: If the crystallization state indicates that crystal nuclei have been formed, the first cooling medium is controlled to increase in temperature at a first predetermined rate based on the first inlet temperature, and the second cooling medium is controlled to decrease in temperature at a second predetermined rate based on the second inlet temperature;

[0123] It should be noted that the first inlet temperature is lower than the second inlet temperature, the first cooling medium and the second cooling medium are cooling media in cooling medium pipes connected to the upper and middle cooling medium inlets of the falling film crystallizer, respectively, and the first inlet temperature and the second inlet temperature are temperatures of the cooling media when entering the upper and middle cooling medium inlets of the falling film crystallizer, respectively;

[0124] Exemplarily, the first inlet temperature is the same as the actual crystallization start temperature of the target product, and the second inlet temperature is the same as the theoretical crystallization start temperature of the target product;

[0125] Exemplarily, the first preset rate is 0.2-0.3°C / min, and the second preset rate is 0.1-0.18°C / min;

[0126] Step S430. Obtaining a first real-time temperature of the first cooling medium and a second real-time temperature of the second cooling medium;

[0127] Step S440: If the first real-time temperature is equal to the second real-time temperature, control the first cooling medium and the second cooling medium to cool down at a third preset rate until the temperature reaches a preset temperature threshold.

[0128] It should be noted that the third preset rate is greater than the first preset rate and the second preset rate, and the preset temperature threshold is less than the first inlet temperature.

[0129] Exemplarily, the third preset rate is 0.3-0.5°C / min,

[0130] The inventors considered that by obtaining the crystallization state of the material to be processed in the falling film crystallizer, the crystallization state includes the formation of crystal nuclei. If the crystallization state is the formation of crystal nuclei, the first cooling medium is controlled to increase the temperature at a first preset rate based on the first inlet temperature, and the second cooling medium is controlled to decrease the temperature at a second preset rate based on the second inlet temperature, to obtain the first real-time temperature of the first cooling medium and the second real-time temperature of the second cooling medium. If the first real-time temperature is equal to the second real-time temperature, the first cooling medium and the second cooling medium are controlled to decrease the temperature at a third preset rate until the preset temperature threshold is reached. That is, the pre-crystallization stage is first heated and then cooled. On the one hand, it can slightly dissolve large-volume crystal nuclei, which is the same as the sweating effect, equivalent to the first sweating of the crystal nuclei. This is beneficial for removing impurities in large-volume crystal nuclei, thereby improving the purity of the crystal nuclei. Since the pre-crystallization stage has initially formed crystal nuclei rapidly, a small amount of impurities are inevitably contained in the crystal nuclei. The slight temperature increase can sweat out some of these impurities in the crystal nuclei, preventing impurities contained in the nucleus from being too deeply wrapped in the later crystal growth stage and difficult to be discharged in the subsequent sweating process. On the other hand, under the same slightly elevated temperature conditions, large nuclei partially melt, leaving their volume virtually unchanged. Only the edge spikes melt, achieving consistent morphology across different nuclei. Under the same slightly elevated temperature conditions, small nuclei completely melt, preventing the precipitation of new nuclei. At this point, the material consists almost exclusively of nuclei of uniform size. Consequently, crystals subsequently grown from these nuclei are uniform in size, improving product quality and purity. Furthermore, by fully utilizing the pre-crystallization stage, the surface area of ​​the crystallization stage is increased, further improving utilization.

[0131] In one embodiment, the temperature control steps are as follows:

[0132] Obtaining a crystallization state of a material to be processed in a falling film crystallizer, wherein the material to be processed is a fluoroethylene carbonate liquid having a purity of 99 wt %, and the crystallization state includes the formation of crystal nuclei;

[0133] If the crystallization state is that crystal nuclei have been formed, the first cooling medium, which is a 30% by volume ethylene glycol aqueous solution, is controlled to be heated at a first preset rate of 0.25° C. / min based on a first inlet temperature (the same as the actual crystallization start temperature of fluoroethylene carbonate), and the second cooling medium, which is a 30% by volume ethylene glycol aqueous solution, is controlled to be cooled at a second preset rate of 0.15° C. / min based on a second inlet temperature of 16° C. (the same as the theoretical crystallization start temperature of fluoroethylene carbonate);

[0134] Acquire a first real-time temperature of the first cooling medium and a second real-time temperature of the second cooling medium;

[0135] If the first real-time temperature is equal to the second real-time temperature, the first cooling medium and the second cooling medium are controlled to cool down at a third preset rate of 0.3° C. / min until the preset temperature threshold is -1° C.

[0136] Example 7

[0137] Referring to FIG. 6 , this embodiment provides a temperature control system M500 for controlling the temperature of the cooling medium in the cooling medium pipes connected to the upper and middle cooling medium inlets of the falling film crystallizer.

[0138] As shown in FIG5 , in an exemplary embodiment of the present application, a temperature control system M500 includes:

[0139] The crystallization state acquisition module M510 is configured to obtain the crystallization state of the material to be processed in the falling film crystallizer, wherein the crystallization state includes the formation of crystal nuclei;

[0140] The first control module M520 is configured to control the first cooling medium to increase its temperature at a first preset rate based on a first inlet temperature, and to control the second cooling medium to decrease its temperature at a second preset rate based on a second inlet temperature, if the crystallization state is that crystal nuclei have been formed;

[0141] It should be noted that the first inlet temperature is lower than the second inlet temperature, the first cooling medium and the second cooling medium are cooling media in cooling medium pipes connected to the upper and middle cooling medium inlets of the falling film crystallizer, respectively, and the first inlet temperature and the second inlet temperature are the temperatures of the first cooling medium and the second cooling medium when they enter the upper and middle cooling medium inlets of the falling film crystallizer, respectively;

[0142] The real-time temperature acquisition module M530 is configured to obtain a first real-time temperature of the first cooling medium and a second real-time temperature of the second cooling medium;

[0143] The second control module M540, if the first real-time temperature is equal to the second cooling medium, cools down according to a third preset rate until it reaches a preset temperature threshold.

[0144] The third preset rate is greater than the first preset rate and the second preset rate, and the preset temperature threshold is less than the first inlet temperature.

[0145] It should be noted that the temperature control system provided in the above embodiment and the temperature control method provided in the above embodiment are based on the same concept. The specific manner in which each module and unit performs operations has been described in detail in the method embodiment and will not be repeated here. In actual applications, the temperature control system for the cooling medium provided in the above embodiment can, as needed, allocate the above functions to different functional modules, that is, divide the internal structure of the device into different functional modules to complete all or part of the functions described above, and this is not limited here.

[0146] An embodiment of the present application also provides an electronic device, comprising: one or more processors; a storage device for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the electronic device implements the temperature control method provided in the above-mentioned embodiments.

[0147] Example 8

[0148] Figure 7 shows a schematic diagram of the structure of a computer system of an electronic device suitable for implementing Example 8 of the present application. It should be noted that the computer system 600 of the electronic device shown in Figure 7 is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0149] As shown in Figure 7, the computer system 600 includes a central processing unit (CPU) 601, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 602 or the program loaded from the storage part 608 into the random access memory (RAM) 603, such as executing the method described in the above embodiment. Various programs and data required for system operation are also stored in the RAM 603. The CPU 601, ROM 602 and RAM 603 are connected to each other via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0150] The following components are connected to the I / O interface 605: an input section 606 including a keyboard, a mouse, and the like; an output section 607 including devices such as a cathode ray tube (CRT), a liquid crystal display (LCD), and a speaker; a storage section 608 including a hard disk; and a communication section 609 including a network interface card such as a LAN (Local Area Network) card or a modem. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to the I / O interface 605 as needed. Removable media 611, such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory, is installed in the drive 610 as needed, so that computer programs read therefrom can be installed into the storage section 608 as needed.

[0151] In particular, according to an embodiment of the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, an embodiment of the present application includes a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a computer program for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network via the communication section 609, and / or installed from a removable medium 611. When the computer program is executed by the central processing unit (CPU) 601, the various functions defined in the system of the present application are executed.

[0152] It should be noted that the computer-readable medium shown in the embodiments of the present application can be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium can be, for example, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media can include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, which carries a computer-readable computer program. This propagated data signal can take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. A computer program embodied on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, or any suitable combination thereof.

[0153] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present application. Among them, each box in the flowchart or block diagram can represent a module, program segment, or part of the code, and the above-mentioned module, program segment, or part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0154] The units involved in the embodiments described in this application may be implemented by software or hardware, and the units described may also be set in a processor. In some cases, the names of these units do not constitute limitations on the units themselves.

[0155] Another aspect of the present application provides a computer-readable storage medium having a computer program stored thereon. When executed by a computer processor, the computer program causes the computer to perform the temperature control method described above. The computer-readable storage medium may be included in the electronic device described in the above embodiments, or may exist independently and not be incorporated into the electronic device.

[0156] Another aspect of the present application provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the temperature control method provided in each of the above embodiments.

[0157] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A falling film crystallization method, the falling film crystallization method comprising feeding, crystallization and melting steps in sequence, characterized in that: After the feeding and before crystallization, an inducing crystallization step is also included, and the inducing crystallization includes: feeding a heat-conducting medium into the upper side of the falling film crystallizer to form crystal nuclei on the upper part of the falling film crystallizer for the material to be processed.

2. The falling film crystallization method according to claim 1, characterized in that The inlet temperature of the heat transfer medium is the actual crystallization start temperature of the target product.

3. The falling film crystallization method according to claim 1, characterized in that: The material to be treated includes fluoroethylene carbonate liquid, acrylic acid liquid or 3,5-dimethylphenol.

4. A falling film crystallizer, characterized in that: The falling film crystallizer includes a shell, the top and bottom of the shell are respectively provided with a material inlet and a material outlet, a plurality of vertically arranged crystallization tubes are arranged inside the shell, an induced crystallization zone and a crystallization zone are sequentially arranged between the material inlet and the material outlet, the induced crystallization zone and the crystallization zone are sequentially provided with a heat transfer medium inlet, a distribution plate, a heat transfer medium outlet and a bottom plate from top to bottom, the distribution plate is arranged in a horizontal direction, a guide is fixedly arranged on the distribution plate, the guide is sleeved on the outside of the crystallization tube, a top plate arranged in a horizontal direction is further arranged between the induced crystallization zone and the material inlet, the top plate and the bottom plate are both provided with a plurality of through holes corresponding to the crystallization tubes one by one, and the top plate and the bottom plate are sleeved on the outside of the crystallization tube through the through holes.

5. A temperature control method for controlling the temperature of a cooling medium in a cooling medium pipeline connected to the cooling medium inlet at the upper part and the middle part of a falling film crystallizer, characterized in that: The temperature control method comprises: Acquiring a crystal state of the material to be processed in the falling film crystallizer, wherein the crystal state includes the formation of crystal nuclei; If the crystallization state is that a crystal nucleus has been formed, the first cooling medium is controlled to be heated at a first preset rate based on a first inlet temperature, and the second cooling medium is controlled to be cooled at a second preset rate based on a second inlet temperature, the first inlet temperature is lower than the second inlet temperature, the first cooling medium and the second cooling medium are respectively cooling media in cooling medium pipelines connected to the upper and middle cooling medium inlets of the falling film crystallizer, and the first inlet temperature and the second inlet temperature are respectively the temperatures of the first cooling medium and the second cooling medium when they enter the upper and middle cooling medium inlets of the falling film crystallizer; Acquire a first real-time temperature of the first cooling medium and a second real-time temperature of the second cooling medium; If the first real-time temperature is equal to the second real-time temperature, the first cooling medium and the second cooling medium are controlled to cool down at a third preset rate until a preset temperature threshold is reached, the third preset rate is greater than the first preset rate and the second preset rate, and the preset temperature threshold is less than the first inlet temperature.

6. The temperature control method according to claim 5, characterized in that: The first inlet temperature is the same as the actual crystallization start temperature of the target product.

7. The temperature control method according to claim 6, characterized in that: The second inlet temperature is the same as the theoretical crystallization start temperature of the target product.

8. A cooling medium temperature control system, the temperature control system is used to control the temperature of the cooling medium in the cooling medium pipeline connected to the cooling medium inlet at the upper part and the middle part of the falling film crystallizer, characterized in that: The temperature control system comprises: A crystallization state acquisition module is configured to obtain the crystallization state of the material to be processed in the falling film crystallizer, wherein the crystallization state includes the formation of crystal nuclei; a first control module, if the crystal state is that a crystal nucleus has been formed, being configured to control the first cooling medium to increase the temperature at a first preset rate based on a first inlet temperature, and to control the second cooling medium to decrease the temperature at a second preset rate based on a second inlet temperature, wherein the first inlet temperature is lower than the second inlet temperature, the first cooling medium and the second cooling medium are respectively cooling media in cooling medium pipelines connected to the upper and middle cooling medium inlets of the falling film crystallizer, and the first inlet temperature and the second inlet temperature are respectively temperatures of the first cooling medium and the second cooling medium when they enter the upper and middle cooling medium inlets of the falling film crystallizer; A real-time temperature acquisition module, configured to acquire a first real-time temperature of the first cooling medium and a second real-time temperature of the second cooling medium; The second control module is configured to control the first cooling medium and the second cooling medium to cool down at a third preset rate until a preset temperature threshold if the first real-time temperature is equal to the second real-time temperature. The third preset rate is greater than the first preset rate and the second preset rate, and the preset temperature threshold is less than the first inlet temperature.

9. An electronic device, characterized in that: The electronic device comprises: one or more processors; A storage device for storing one or more programs, when the one or more programs are executed by the one or more processors, enables the electronic device to implement the temperature control method as described in any one of claims 5-7.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed by a processor of a computer, the computer is caused to execute the temperature control method as described in any one of claims 5 to 7.

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