Heat exchange system, melt crystallization system and melt crystallization method

Abstract

The invention relates to a heat exchange system, a melt crystallization system and a melt crystallization method.The heat exchange system comprises flash evaporation equipment, a refrigerant storage container and a heating medium storage container, the flash evaporation equipment is provided with a liquid inlet, a liquid outlet and a steam outlet, the liquid outlet is connected with the refrigerant storage container, and the steam outlet is connected with the heating medium storage container; a heating mechanism is arranged on the pipeline between the steam outlet and the heating medium storage container, and the heat exchange system further comprises a temperature adjusting mechanism which comprises a heating medium conveying assembly. The flash evaporation equipment and the heating mechanism are additionally arranged, so that the dependence on external refrigerants and heating media is reduced, and the energy consumption and the cost are reduced; by additionally arranging the temperature adjusting mechanism, the technical problems that the product purity, the crystal morphology, the production efficiency and the like are affected due to temperature control precision reduction can be avoided; by additionally arranging the heating medium conveying assembly, the technical problems that the temperature control precision is reduced, and the product purity, the crystal morphology, the production efficiency and the like are affected can be solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical engineering, and particularly relates to a heat exchange system, a melt crystallization system and a melt crystallization method. Background Art

[0002] Melt crystallization is a method of separating products by gradually reducing the temperature of a liquid material to be purified according to the melting point differences between components in the material to be purified, so that the target component reaches the phase equilibrium freezing point and supersaturated state, gradually precipitating crystals from the material to be purified, and realizing the separation of the product through remelting and purification. Melt crystallization has low energy consumption (only 10%-30% of that of distillation), no pollution, no need for solvents, low operating temperature, high product purity, environmental friendliness, and a wide range of applications (applicable to special systems such as isomers and chiral substances, and also applicable to heat-sensitive substances, dilute solutions, and high-boiling substances), and is widely used in the separation and purification of chemical intermediates, pharmaceutical intermediates, biochemical products and other substances.

[0003] Generally speaking, melt crystallization usually includes crystallization, sweating and melting steps. Crystallization means that the material to be purified (i.e., liquid molten material) exchanges heat with a refrigerant introduced from the outside, and the temperature of the material to be purified decreases slowly. During this process, the target component in the material to be purified turns into crystals and precipitates. The content of the target component in the crystal layer formed after crystallization is higher than that in the initial material, and the content of the target component in the "residual liquid" formed is lower than that in the initial material. The sweating process means that the crystals after crystallization exchange heat with a heat medium introduced from the outside, and the temperature of the crystals after crystallization gradually rises. During this process, the crystals gradually melt to form "sweat". Melting is that the "sweat" exchanges heat with a heat medium introduced from the outside until the temperature in the crystallizer reaches the melting point of the target component to melt the "sweat" and form a molten liquid.

[0004] However, during the melt crystallization process, introducing refrigerants and heat media from the outside to meet the heat demand not only consumes a large amount of energy and increases production costs, but also the introduced external system increases the complexity and instability of production. For example, fluctuations in the supply of external cold sources and heat sources may lead to a decrease in the temperature control accuracy during the melt crystallization process, thereby affecting the product purity, crystal morphology and production efficiency. At the same time, the purchase, maintenance and operation of external energy supply equipment also occupy a large amount of capital and labor input. Summary of the Invention

[0005] In view of this, the present invention provides a heat exchange system, a melt crystallization system and a melt crystallization method to solve the problems that fluctuations in the supply of external cold sources and heat sources may lead to a decrease in the temperature control accuracy during the crystallization process, affecting the crystallization purity, crystal morphology and production efficiency of the product, and the purchase, maintenance and operation of external energy supply equipment also occupy a large amount of capital and labor input.

[0006] To implement the above solution, the technical solution of the present invention is as follows: In a first aspect, the present application provides a heat exchange system, which includes a flash evaporation device, a refrigerant storage container, and a heat medium storage container. The flash evaporation device is provided with a liquid inlet, a liquid outlet, and a steam outlet. The liquid outlet is connected to the refrigerant storage container, and the steam outlet is connected to the heat medium storage container. A temperature increasing mechanism for increasing the temperature of the steam obtained after being processed by the flash evaporation device is provided on the pipeline between the steam outlet and the heat medium storage container. The heat exchange system further includes a temperature adjustment mechanism for adjusting the temperature of the heat medium stored in the heat medium storage container to a first preset target temperature. The temperature adjustment mechanism includes a heat medium conveying component for uniformly mixing the steam processed by the temperature increasing mechanism with the heat medium stored in the heat medium storage container, so as to adjust the temperature of the obtained mixed heat medium to the first preset target temperature.

[0007] The principle of the heat exchange system of the present application is as follows: By adding a flash evaporation device, the refrigerant after heat exchange (i.e., the refrigerant after absorbing heat) during the melt crystallization process can be flash-evaporated, converting the refrigerant after heat exchange into steam and liquid. By connecting the steam outlet of the flash evaporation device to the heat medium storage container and adding a temperature increasing mechanism on the pipeline between the steam outlet and the heat medium storage container, the steam obtained after flash evaporation can be heated by the temperature increasing mechanism. The steam processed by the temperature increasing mechanism can enter the heat medium storage container through the pipeline between the temperature increasing mechanism and the heat medium storage container, and be mixed with the heat medium after heat exchange stored in the heat medium storage container. During the mixing process, the heat of the steam processed by the temperature increasing mechanism is transferred to the heat medium after heat exchange to obtain a mixed heat medium as a new heat medium for the subsequent heating and melting process, and the liquid obtained by the flash evaporation process is used as a new refrigerant for the subsequent melt crystallization process, reducing the dependence on exogenous refrigerants and heat media, thereby reducing energy consumption and costs; by adding a temperature adjustment mechanism, the temperature of the heat medium stored in the heat medium storage container can be adjusted to the first preset target temperature, avoiding technical problems such as a decrease in the temperature control accuracy during the melt crystallization process caused by large temperature fluctuations of the heat medium stored in the heat medium storage container, which affect the purity, crystal morphology, and production efficiency of the product; by adding a heat medium conveying component, the steam processed by the temperature increasing mechanism can be uniformly mixed with the heat medium stored in the heat medium storage container, enhancing the mixing effect between the steam processed by the temperature increasing mechanism and the heat medium after heat exchange, so as to adjust the temperature of the obtained mixed heat medium to the first preset target temperature, avoiding technical problems such as a large temperature gradient and a decrease in the temperature control accuracy during the melt crystallization process caused by poor mixing between the steam processed by the temperature increasing mechanism and the heat medium after heat exchange, which affect the purity, crystal morphology, and production efficiency of the product.

[0008] Optionally, a plurality of temperature monitors are provided in the heat medium storage container along the height direction.

[0009] Optionally, the temperature regulating mechanism further includes a heat exchanger for adjusting the temperature of the heat medium initially stored in the heat medium storage container to the first preset target temperature.

[0010] Optionally, the heat medium storage container is provided with a heat medium outlet end and a heat medium inlet end. The temperature regulating mechanism further includes a cooler for exchanging heat between a part of the mixed heat medium stored in the heat medium storage container and circulating water so as to adjust the temperature of the remaining mixed heat medium to the first preset target temperature. The first end of the cooler is connected to the heat medium outlet end, and the second end of the cooler is connected to the heat medium inlet end.

[0011] Specifically, by adding a cooler in this application, connecting the first end of the cooler to the heat medium outlet end, and connecting the second end of the cooler to the heat medium inlet end, it is possible to cool a part of the mixed heat medium in the heat medium storage container through the cooler to remove the excess heat generated during the heating process, so as to keep the system in heat balance; at the same time, adjust the balance state of the heating and cooling loads generated during the heating and cooling stages of the melt crystallization process and the heat balance state of the heat loss between the melt crystallization system and the outside world, so that the heat of the melt crystallization system remains balanced, thereby ensuring the continuous and stable operation of the system.

[0012] In a second aspect, the present application further provides a melt crystallization system. The melt crystallization system includes the heat exchange system as described above. The melt crystallization system further includes a melt crystallization device. The melt crystallization device is provided with a cold and heat medium outlet end, and the cold and heat medium outlet end is connected to the liquid inlet.

[0013] Optionally, a plurality of temperature monitors are provided in the melt crystallization device along the height direction.

[0014] In a third aspect, the present application further provides a melt crystallization method. The melt crystallization method sequentially includes melt crystallization and heating and melting. The refrigerant after heat exchange in the melt crystallization process is subjected to flash evaporation treatment to obtain steam and liquid; The steam is heated to obtain heated steam; The temperature of the liquid is adjusted to a second preset temperature range; During the melt crystallization process, the liquid after temperature adjustment is used as a new refrigerant to perform melt crystallization on the material to be purified; The heated steam is mixed with the heat medium after heat exchange in the melt crystallization process to obtain a mixed heat medium, and the temperature of the mixed heat medium is adjusted to a first preset temperature range; During the heating and melting process, the mixed heat medium after temperature adjustment is used as a new heat medium for heating and melting.

[0015] Optionally, the melt crystallization method further includes the following steps: During the heating and melting process, heat is transferred to the outside, so that the inside of the melt crystallization system is in a heat balance state during the melt crystallization and heating and melting processes.

[0016] Optionally, the melt crystallization method further includes the following steps: During the melt crystallization process, the temperatures of a plurality of sites are obtained, and all the sites are arranged in sequence along the height direction inside the container for storing the heat medium; Estimate the final temperature after temperature balance at each place in the heat medium storage container according to the temperature; Adjust the heat transferred to the outside according to the final temperature.

[0017] Specifically, due to the uneven temperature distribution of the heat medium in the heat medium storage container (showing a stepped distribution with the temperature decreasing from top to bottom), if the prior art is used to monitor the temperature of the heat medium storage container or the heat medium outlet end, there is a large gap from the actual final temperature after heat balance in the container. This will cause excessive heat to be transferred to the outside, resulting in the actual final temperature being lower than the monitored temperature, making the process of transferring heat to the outside in an oscillating state, and the final temperature rising and falling around the first preset temperature range. Not only is it difficult to accurately control the final temperature, but also the external heat transfer cost is increased.

[0018] However, through this solution, adjusting the heat transferred to the outside according to the final temperature, that is, by the way that the external heat exchange temperature gradually approaches the estimated final temperature, can greatly reduce the oscillating state and stably control the final temperature within the first preset temperature range. Exemplarily, the final temperature (i.e., the final temperature t) is determined in the following manner. Specifically: Considering that the heat medium in the heat medium storage container is in a gas-liquid coexistence state after the heating treatment, when the densities and specific heat capacities of each layer (i.e., the monitoring areas corresponding to each temperature detector) are different, the final temperature t is determined by the heat conservation of each layer. The heat calculation needs to consider the mass (volume * density) and specific heat capacity of each layer. The formula derivation is as follows: 1. The total heat before mixing, that is, the sum of the heats of each layer, is shown in formula (a): (a); In the formula , is the density and specific heat capacity of the steam layer, and its value is determined by the output parameters of the heating mechanism and does not need to be monitored; , is the density and specific heat capacity of the liquid layer, and the constant does not need to be monitored; is the volume of the first layer (i.e., the area detected by the topmost temperature detector), is the volume of the second layer (i.e., the area detected by the second topmost temperature detector), and so on; 2. The total heat after mixing is shown in formula (b): (b); The final temperature is t; 3. Heat conservation: From it is obtained that the final temperature (i.e., the final temperature t) is as shown in Equation (c): (c); That is, the final temperature t is the weighted average of the volume * density * specific heat capacity * temperature of each layer, and the weight is the product of the volume, density, and specific heat capacity of each layer: .

[0019] Wherein , , and , . Description of the Drawings

[0020] Figure 1 is a schematic structural diagram of the heat exchange system of Embodiment 1; Figure 2 is a schematic structural diagram of the heat exchange system of Embodiment 2; Figure 3 is a schematic structural diagram of the melt crystallization system of Embodiment 3; Figure 4 is a schematic diagram of adjusting the heat transferred to the outside according to the final temperature in Embodiment 4; Figure 5 is a schematic diagram of adjusting the heat transferred to the outside in Comparative Example 2.

[0021] Reference Signs 1 - Flash device; 2 - Refrigerant collection pump; 3 - Refrigerant storage container; 4 - Heating mechanism; 5 - Heat medium storage container; 6 - Heat medium mixing pump; 7 - Cooler; 8 - Melt crystallization device; 9 - Transfer pump. Detailed Embodiments

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] In the present invention, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" shall be understood in a broad sense. For example, "fixation" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text is that it includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0025] An embodiment of the present application provides a heat exchange system, including a flash evaporation device 1, a refrigerant storage container 3, and a heat medium storage container 5. The flash evaporation device 1 is provided with a liquid inlet, a liquid outlet, and a steam outlet. The liquid outlet is connected to the refrigerant storage container 3, and the steam outlet is connected to the heat medium storage container 5. A temperature increasing mechanism 4 for increasing the temperature of the steam obtained after being processed by the flash evaporation device 1 is provided on the pipeline between the steam outlet and the heat medium storage container 5. The heat medium storage container 5 is provided with a heat medium outlet end and a heat medium inlet end; the heat exchange system further includes a temperature adjustment mechanism for adjusting the temperature of the heat medium stored in the heat medium storage container 5 to a first preset target temperature. The temperature adjustment mechanism includes a heat exchanger for adjusting the temperature of the initially stored heat medium in the heat medium storage container to the first preset target temperature. The temperature adjustment mechanism further includes a heat medium conveying assembly for making the steam processed by the temperature increasing mechanism mix evenly with the heat medium stored in the heat medium storage container, so as to adjust the temperature of the obtained mixed heat medium to the first preset target temperature.

[0026] In another embodiment, the temperature adjustment mechanism further includes a cooler 7 for exchanging heat between a part of the mixed heat medium stored in the heat medium storage container 5 and circulating water, so as to adjust the temperature of the remaining mixed heat medium to the first preset target temperature. The first end of the cooler 7 is connected to the heat medium outlet end, and the second end of the cooler 7 is connected to the heat medium inlet end.

[0027] Another embodiment of the present application further provides a melt crystallization system, which includes the heat exchange system and melt crystallization equipment 8 as described above. The melt crystallization equipment 8 is provided with a cold and hot medium outlet end, which is connected to the liquid inlet.

[0028] Optionally, a plurality of temperature monitors are provided in the melt crystallization device 8 along the height direction.

[0029] Another embodiment of the present application further provides a melt crystallization method, which comprises melt crystallization and temperature-raising melting in sequence, wherein the refrigerant after heat exchange in the melt crystallization process is flash-evaporated to obtain steam and liquid; The steam is subjected to a heating treatment to obtain heated steam; adjusting the temperature of the liquid to within a second preset temperature range; In the melt crystallization process, the temperature-adjusted liquid is used as a new refrigerant to melt crystallize the material to be purified; Mixing the heated steam with the heat medium after heat exchange during the melting and crystallization process to obtain a mixed heat medium, and adjusting the temperature of the mixed heat medium to a first preset temperature range; In the heating and melting process, the mixed heat medium after temperature adjustment is used as a new heat medium for heating and melting.

[0030] In another embodiment, the melt crystallization method further comprises the following steps: During the temperature rise and melting process, heat is transferred to the outside, so that the inside of the melt crystallization system is in a thermal equilibrium state during the melt crystallization and temperature rise and melting processes.

[0031] In another embodiment, the melt crystallization method further comprises the following steps: During the melt crystallization process, the temperatures of several locations are obtained, all of which are located in a container for storing heat medium and are arranged in sequence along the height direction; Estimate the final temperature of the heat medium storage container after the temperature at each location is balanced based on the temperature; The heat transferred to the outside is regulated according to the final temperature.

[0032] The present invention is described in detail below by specific examples. It should also be understood that the following examples are only used to specifically illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are also only examples within a suitable range, that is, those skilled in the art can make a selection within a suitable range through the description herein, and are not limited to the specific values ​​​​exemplified below.

[0033] Embodiment 1: See also Figure 1 ,Figure 1 The figure is a schematic structural diagram of the heat exchange system of this embodiment. The heat exchange system includes a flash evaporation device 1, a refrigerant storage container 3, a temperature rising mechanism 4, and a heat medium storage container 5.

[0034] Please refer to Figure 1 , the flash evaporation device 1 is used as a place for flash evaporation of the refrigerant after heat exchange in the melt crystallization process (that is, the refrigerant after absorbing heat), so that the refrigerant after heat exchange is converted into steam and liquid. The flash evaporation device 1 is provided with a liquid inlet, a liquid outlet, and a steam outlet. The liquid outlet is provided with a temperature control component (not shown). The liquid outlet is connected to the refrigerant storage container 3, and the steam outlet is connected to the heat medium storage container 5. A refrigerant collection pump 2 is provided on the pipeline between the liquid outlet and the refrigerant storage container 3. The flash evaporation device 1 can adopt a flash evaporation tank, a flash evaporator, etc. The flash evaporation tank, the flash evaporator, etc. are prior arts and will not be elaborated here.

[0035] Please continue to refer to Figure 1 , the refrigerant storage container 3 is used as a place for storing the initial refrigerant and the liquid obtained by flash evaporation, so as to use the liquid obtained by flash evaporation as a cooling medium (that is, the refrigerant) for subsequent melt crystallization. The refrigerant storage container 3 is provided with a liquid inlet end, a liquid outlet end, a liquid level gauge (not shown), and a temperature adjustment component (not shown). The liquid inlet end of the refrigerant storage container 3 is connected to the liquid outlet of the flash evaporation device 1.

[0036] Please continue to refer to Figure 1 , the temperature rising mechanism 4 is used as a place for raising the temperature of the steam obtained after being processed by the flash evaporation device 1. The temperature rising mechanism 4 is located on the pipeline between the steam outlet of the flash evaporation device 1 and the heat medium storage container 5. The temperature rising mechanism 4 can adopt a heater, a compressor, etc. The heater, the compressor, etc. are prior arts and will not be elaborated here.

[0037] Please continue to refer to Figure 1 , the heat medium storage container 5 is used as a place for mixing the heat medium after heat exchange and the steam obtained after compression and processed by the temperature rising mechanism. During the mixing process, the heat of the steam processed by the temperature rising mechanism is transferred to the heat medium after heat exchange, and the obtained mixed heat medium can be used as a new heat medium for subsequent heating and melting processes. The heat medium storage container 5 is provided with a heat medium inlet end, a heat medium outlet end, a liquid level gauge (not shown), and a temperature adjustment component (not shown). Along the height direction, several temperature monitors (not shown) are provided in the heat medium storage container 5. The heat exchange system further includes a temperature adjustment mechanism. The temperature adjustment mechanism includes a heat exchanger (not shown) for adjusting the temperature of the heat medium initially stored in the heat medium storage container 5 (that is, the heat medium stored in the heat medium storage container 5 at the beginning of purification) to a first preset target temperature. The first preset target temperature can be set by itself, for example, the highest temperature required for melting. Exemplarily, the first preset target temperature can be set to be 8 - 12 °C higher than the temperature of the material to be purified. The temperature monitors can include, for example, thermometers, pyrometers, etc.

[0038] Please refer to Figure 1 , the heat exchange system further includes a heat medium conveying component for evenly mixing the steam processed by the temperature raising mechanism 4 with the heat medium stored in the heat medium storage container 5, so as to adjust the temperature of the obtained mixed heat medium to the first preset target temperature. The heat medium conveying component can be a heat medium conveying pipeline. Both ends of the heat medium conveying pipeline are respectively connected to the heat medium outlet end and the heat medium inlet end of the heat medium storage container 5, that is, the heat medium outlet end and the heat medium inlet end of the heat medium storage container 5 are connected through the heat medium conveying pipeline, and a heat medium mixing pump 6 is provided on the heat medium conveying pipeline.

[0039] Specifically, in this embodiment, by adding a heat medium conveying component, the steam processed by the temperature raising mechanism can be evenly mixed with the heat medium stored in the heat medium storage container 5 through the heat medium conveying component and the heat medium mixing pump 6, enhancing the mixing effect between the steam processed by the temperature raising mechanism 4 and the heat medium after heat exchange, so as to adjust the temperature of the obtained mixed heat medium to the first preset target temperature, and avoiding technical problems such as a large temperature gradient and a decrease in the temperature control accuracy during the melting and crystallization process caused by poor mixing between the steam processed by the temperature raising mechanism 4 and the heat medium after heat exchange, which affect the purity, crystal morphology and production efficiency of the product.

[0040] The principle of the heat exchange system in this embodiment is as follows: By adding a flash evaporation device 1, the refrigerant after heat exchange in the melt crystallization process (i.e., the refrigerant after absorbing heat) can be flash-evaporated, so that the refrigerant after heat exchange (i.e., the refrigerant after heat exchange in the melt crystallization process. After melt crystallization, the initial refrigerant exchanges heat with the material to be purified, and the temperature of the initial refrigerant rises to obtain the refrigerant after heat exchange) is converted into steam and liquid. By connecting the gas outlet and the steam outlet of the flash evaporation device 1 to the heat medium storage container 5 and adding a temperature-raising mechanism 4 on the pipeline between the steam outlet and the heat medium storage container 5, the steam obtained after flash evaporation can be heated by the temperature-raising mechanism 4. After being processed by the temperature-raising mechanism, the steam can enter the heat medium storage container 5 through the pipeline between the temperature-raising mechanism 4 and the heat medium storage container 5 and be mixed with the heat-exchanged heat medium stored in the heat medium storage container 5 (i.e., the heat-exchanged heat medium after the temperature-raising and melting process. After temperature-raising and melting, the temperature of the initial heat medium drops to obtain the heat-exchanged heat medium). During the mixing process, the heat of the steam processed by the temperature-raising mechanism is transferred to the heat-exchanged heat medium to obtain a mixed heat medium that can be used as a new heat medium, and the liquid obtained by flash evaporation is used as the refrigerant in the subsequent melt crystallization process, reducing the dependence on exogenous refrigerants and heat media, thereby reducing energy consumption and costs. By adding a temperature adjustment mechanism, the temperature of the heat medium stored in the heat medium storage container can be adjusted to the first preset target temperature, avoiding technical problems such as a decrease in the temperature control accuracy of the melt crystallization process caused by large temperature fluctuations of the heat medium stored in the heat medium storage container, which affect the purity, crystal morphology, and production efficiency of the product; by adding a heat medium delivery component, the steam processed by the temperature-raising mechanism can be evenly mixed with the heat medium stored in the heat medium storage container, enhancing the mixing effect between the steam processed by the temperature-raising mechanism and the heat-exchanged heat medium, so that the temperature of the obtained mixed heat medium is adjusted to the first preset target temperature, avoiding technical problems such as a large temperature gradient and a decrease in the temperature control accuracy of the melt crystallization process caused by poor mixing between the steam processed by the temperature-raising mechanism and the heat-exchanged heat medium, which affect the purity, crystal morphology, and production efficiency of the product.

[0041] Embodiment 2 Please refer to Figure 2 , the difference between this embodiment and Embodiment 1 is that the temperature adjustment mechanism further includes a cooler 7 for exchanging heat between a part of the mixed heat medium stored in the heat medium storage container 5 and circulating water to adjust the temperature of the remaining mixed heat medium to the first preset target temperature. The first end of the cooler 7 is connected to the heat medium outlet end, and the second end of the cooler 7 is connected to the heat medium inlet end.

[0042] Specifically, in this embodiment, by adding a cooler 7 and connecting the first end of the cooler 7 to the hot medium outlet end and the second end of the cooler 7 to the hot medium inlet end, it is possible to cool a part of the mixed hot medium in the hot medium storage container 5 through the cooler 7 to remove the excess heat generated during the heating process, so as to keep the system in heat balance. At the same time, the cooler 7 can cool a part of the mixed hot medium in the hot medium storage container 5, remove the excess heat generated during the heating process, adjust the balance state of the hot and cold loads generated during the heating and cooling stages in the purification process and the heat balance state of the heat loss between the melt crystallization system and the outside world, keep the heat of the melt crystallization system in balance, and thus ensure the continuous and stable operation of the system.

[0043] Embodiment 3: Please refer to Figure 3 , Figure 3 , which is a schematic structural diagram of the melt crystallization system of this embodiment. The melt crystallization system includes the heat exchange system and the melt crystallization equipment 8 shown in Embodiment 2.

[0044] Please continue to refer to Figure 3 , the melt crystallization equipment 8 is used as a place for gradually reducing the temperature of the liquid to-be-purified material according to the melting point difference between the components in the to-be-purified material, so that the target component reaches the phase equilibrium freezing point and supersaturated state, gradually precipitating crystals from the to-be-purified material, and realizing the separation of the product through remelting purification. The melt crystallization equipment 8 is provided with a hot and cold medium inlet end and a hot and cold medium outlet end. The hot and cold medium outlet end of the melt crystallization equipment 8 is connected to the hot and cold medium inlet end. The hot and cold medium inlet end of the melt crystallization equipment 8 is connected to the liquid outlet end of the refrigerant storage container 3 and the hot medium outlet end of the hot medium storage container 5. The hot and cold medium outlet end of the melt crystallization equipment 8 is connected to the liquid inlet of the flash evaporation equipment 1 and the hot medium inlet end of the hot medium storage container 5. A transfer pump 9 and a flow regulator (not shown) are provided on the pipeline between the hot and cold medium inlet end of the melt crystallization equipment 8 and the liquid outlet of the refrigerant storage container 3 and on the pipeline between the hot and cold medium inlet end of the melt crystallization equipment 8 and the hot medium outlet end of the hot medium storage container 5. A plurality of temperature sensors are arranged in the melt crystallization equipment 8 along the height direction, and the temperature sensors are used to monitor the temperature at different height positions in the melt crystallization equipment 8.

[0045] Embodiment 4: Using the melt crystallization system of Embodiment 3 (the heating mechanism 4 uses a compressor, and there are 4 temperature monitors in the hot medium storage container 5 along the height direction) to perform melt crystallization on liquid naphthalene with a purity of 96.00 wt% (detected by gas chromatography). The melt crystallization equipment uses a swirl falling film crystallizer, and its structure is as shown in Embodiment 2 of CN202210044553.1). The specific steps are as follows: Introduce liquid naphthalene with a purity of 96.00 wt% into the melt crystallization device 8. Start the transfer pump 9 on the pipeline between the cold and hot medium inlet end of the melt crystallization device 8 and the liquid outlet of the refrigerant storage container 3, and adjust the flow rate of the refrigerant so that the material temperature can accurately decrease according to the predetermined cooling curve, with the cooling rate deviation controlled within ±0.2 °C / min, and the lowest temperature in the crystallization stage is set at 60 °C; The refrigerant (specifically water at a temperature of 60 °C) absorbs heat and heats up in the melt crystallization device and then enters the flash evaporation device 1. Set the temperature in the flash evaporation device 1 to 60 °C and the pressure to 20 kPa, so that part of the refrigerant undergoes flash evaporation to obtain liquid and steam. Adjust the temperature of the liquid outlet of the flash evaporation device 1 to the lowest temperature. The low-temperature liquid is pumped by the refrigerant collection pump 2 and cached in the refrigerant storage container 3, while the low-temperature steam enters the heating mechanism 4 and is compressed into steam after being processed by the heating mechanism. The steam after being processed by the heating mechanism enters the heat medium storage container 5 through the pipeline between the heating mechanism 4 and the heat medium storage container 5, and is mixed with the heat medium (water at a temperature of 76 - 90 °C) cached in the heat medium storage container 5 to obtain a mixed heat medium; Send part of the mixed heat medium in the heat medium storage container 5 into the cooler 7 through the heat medium mixing pump 6 for cooling treatment to absorb excess heat, obtaining a coolant and cooling steam. The cooling steam returns to the heat medium storage container 5 through the pipeline between the cooler 7 and the heat medium inlet end of the heat medium storage container 5. The remaining mixed heat medium in the heat medium storage container 5 is pumped by the heat medium mixing pump 6 on the pipeline between the heat medium outlet end and the heat medium inlet end of the heat medium storage container 5 and circulated back into the heat medium storage container 5 to enhance the mixing effect in the heat medium storage container 5. After the temperature of the new heat medium in the heat medium storage container 5 reaches the highest temperature of 90 °C required by the melt crystallization device 8, turn off the heat medium mixing pump; Open the transfer pump 9 on the pipeline between the cold and hot medium inlet end of the melt crystallization device 8 and the heat medium storage container 5, and transport the new heat medium in the heat medium storage container 5 to the melt crystallization device 8. Adjust the flow rate of the new heat medium so that the material temperature can accurately increase according to the predetermined heating curve, with the heating rate deviation controlled within ±0.2 °C / min; During the melt crystallization process, obtain the temperatures of all sites located in the heat medium storage container 5 and set along the height direction; Estimate the final temperature after the temperature balance at each part of the heat medium storage container 5 based on the temperature. Specifically, considering that the heat medium in the heat medium storage container 5 is in a gas-liquid coexistence state after the heating treatment, when the densities and specific heat capacities of each layer (i.e., the monitoring areas corresponding to each temperature detector) are different, the final temperature t is determined by the heat conservation of each layer. The heat calculation needs to consider the mass (volume * density) and specific heat capacity of each layer. The formula derivation is as follows: 1. The total heat before mixing and the sum of the heat of each layer are shown in Equation (a): (a); Wherein , is the density and specific heat capacity of the steam layer, and its value is determined by the output parameters of the heating mechanism and does not need to be monitored; , is the density and specific heat capacity of the liquid layer, and the constant does not need to be monitored; is the volume of the first layer (i.e., the area detected by the topmost temperature detector), is the volume of the second layer (i.e., the area detected by the second topmost temperature detector), and so on; 2. The total heat after mixing is shown in Equation (b): (b); The final temperature is t; 3. Heat conservation: From it can be obtained that the final temperature (i.e., the final temperature t) is shown in Equation (c): (c); That is, the final temperature is the weighted average of the volume * density * specific heat capacity * temperature of each layer, and the weight is the product of the volume, density, and specific heat capacity of each layer: .

[0046] Wherein , , and , ; Adjust the heat transferred to the outside according to the final temperature. Specifically, adjust the heat transferred to the outside according to Figure 4 , where the target temperature is 90 °C, T4 is the temperature value detected by the lowermost temperature detector, and the flow ratio is the ratio of the actual flow rate of the circulating water in the cooler 7 to the maximum flow rate of the circulating water that can be processed in the cooler 7. Exemplarily, a flow ratio of 0.6 means that the ratio of the actual flow rate of the circulating water in the cooler 7 to the maximum flow rate of the circulating water that can be processed in the cooler 7 is 0.6. The time in the attached drawing refers to the time starting from when the heating mechanism starts heating. Exemplarily, 1 min means 1 min after heating; The new heat medium flows out of the melt crystallization device 8 after heat exchange. A part of it circulates back into the melt crystallization device 8 through the pipeline between the hot and cold heat medium outlet end and the hot and cold heat medium inlet end, and is mixed with the heat exchange medium in the heat medium storage container 5 to balance the temperature and flow rate. A part enters the flash evaporation device 1 to supplement the heat conduction medium that enters the heat medium system due to the flash evaporation of the cooling medium. The remaining part enters the heat medium storage container 5 for buffering; The purity of the obtained product is detected by gas chromatography. After detection, the purity is 98.83 wt%.

[0047] In production according to this embodiment, the energy obtained from the outside is the electricity consumption of the compressor and the amount of circulating water used in the cooler. Among them, the cost of circulating water can be ignored. Therefore, calculated according to the electricity price of 0.52 yuan / kW·h, in production according to this embodiment, the heat energy consumption cost = electricity consumption of the compressor * electricity price = 35 kW * 0.52 yuan / kW·h = 18.2 yuan / h.

[0048] Comparative Example 1: The difference between this comparative example and Example 4 is that an external refrigerant heat exchanger is used to supply refrigerant (specifically, circulating water at a temperature of 60°C), and an external heat medium heat exchanger is used to supply heat medium (specifically, 0.1 MPa saturated steam), and the steam consumption is 0.21 t / h.

[0049] The purity of the obtained product was detected by gas chromatography. After detection, the purity was 98.79 wt%.

[0050] In production according to this comparative example, the energy obtained from the outside is the steam consumption and the amount of circulating water used in the refrigerant heat exchanger. Among them, the cost of circulating water can be ignored. Therefore, calculated according to the steam price of 200 yuan / t, in production according to this comparative example, the heat energy consumption cost = steam consumption * steam price = 200 yuan / t * 0.21 t / h = 58 yuan / h.

[0051] It can be seen from the above Example 4 and Comparative Example 1 that compared with Comparative Example 1, the heat energy consumption cost of Example 4 is reduced by about 68.6%. This result shows that by adding a flash evaporation device in the present application, the refrigerant after heat exchange (i.e., the refrigerant after absorbing heat) in the melt crystallization process can be flash-evaporated, so that the refrigerant after heat exchange is converted into steam and liquid. By connecting the air outlet and the steam outlet of the flash evaporation device to the heat medium storage container and adding a compressor on the pipeline between the steam outlet and the heat medium storage container, the steam obtained after flash evaporation can be heated and pressurized by the compressor, and the steam processed by the heating mechanism can enter the heat medium storage container through the pipeline between the compressor and the heat medium storage container, and be mixed with the heat-exchanged heat medium stored in the heat medium storage container. During the mixing process, the heat of the steam processed by the heating mechanism is transferred to the heat-exchanged heat medium to obtain a mixed heat medium that can be used as a new heat medium (i.e., the heat medium), and the liquid obtained by flash evaporation is used as the cooling medium (i.e., the refrigerant) in the subsequent melt crystallization process, reducing the dependence on external refrigerants and heat media, and thus reducing energy consumption and costs.

[0052] Comparative Example 2: The difference between this comparative example and Example 1 is that the final temperature after the temperature balance at each part of the heat medium storage container 5 is not estimated, and the heat transferred to the outside is not adjusted according to the final temperature. That is, in this comparative example, the heat transferred to the outside is adjusted according to the monitored temperature, specifically adjusted as shown in Figure 5 shown.

[0053] The purity of the obtained product was detected by gas chromatography. After detection, the purity was 98.80 wt%.

[0054] According to this comparative example for production, the energy obtained from the outside was the steam consumption and the circulating water consumption of the refrigerant heat exchanger.

[0055] As can be seen from the above Example 4 and Comparative Example 2, compared with Comparative Example 2, the circulating water flow rate in Example 4 was reduced by 14%, that is, the circulating water consumption was reduced by 14%. This result shows that by estimating the final temperature after the temperature balance at each part of the heat medium storage container 5 and adjusting the heat transferred to the outside according to the final temperature, the way that the outside heat exchange temperature gradually approaches the estimated final temperature reduces the circulating water consumption, reduces the outside heat transfer cost, can also reduce the number of adjustments, reduce the oscillation state, avoid the multiple oscillating adjustments, and reduce the operation cost.

[0056] The above embodiments merely illustrate the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes completed by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A heat exchange system, characterized in that: The heat exchange system includes a flash evaporation device, a refrigerant storage container and a heat medium storage container. The flash evaporation device is provided with a liquid inlet, a liquid outlet and a steam outlet. The liquid outlet is connected to the refrigerant storage container, and the steam outlet is connected to the heat medium storage container. A heating mechanism for increasing the temperature of the steam obtained after being treated by the flash evaporation device is provided on the pipeline between the steam outlet and the heat medium storage container. The heat exchange system also includes a temperature regulating mechanism for regulating the temperature of the heat medium stored in the heat medium storage container to a first preset target temperature. The temperature regulating mechanism includes a heat medium transport component for evenly mixing the steam treated by the heating mechanism with the heat medium stored in the heat medium storage container so that the temperature of the obtained mixed heat medium is adjusted to the first preset target temperature.

2. The heat exchange system according to claim 1, characterized in that: A plurality of temperature monitors are arranged in the heat medium storage container along the height direction.

3. The heat exchange system according to claim 1, characterized in that: The temperature adjustment mechanism further includes a heat exchanger for adjusting the temperature of the heat medium initially stored in the heat medium storage container to the first preset target temperature.

4. The heat exchange system according to claim 1, characterized in that: The heat medium storage container is provided with a heat medium outlet end and a heat medium inlet end, and the temperature regulating mechanism also includes a cooler for exchanging heat between a portion of the mixed heat medium stored in the heat medium storage container and circulating water so as to adjust the temperature of the remaining mixed heat medium to the first preset target temperature, wherein the first end of the cooler is connected to the heat medium outlet end, and the second end of the cooler is connected to the heat medium inlet end.

5. A melt crystallization system, characterized in that: The melt crystallization system comprises the heat exchange system according to any one of claims 1 to 4; The melt crystallization system further comprises a melt crystallization device, wherein the melt crystallization device is provided with a cold and hot medium outlet end, and the cold and hot medium outlet end is connected to the liquid inlet.

6. A melt crystallization method, which comprises melt crystallization and temperature-raising melting in sequence, characterized in that: Flash evaporating the refrigerant after heat exchange in the melt crystallization process to obtain steam and liquid; Performing a temperature-raising treatment on the steam to obtain heated steam; adjusting the temperature of the liquid to within a second preset temperature range; In the melt crystallization process, the temperature-adjusted liquid is used as a new refrigerant to melt crystallize the material to be purified; Mixing the heated steam with the heat medium after heat exchange during the melting and crystallization process to obtain a mixed heat medium, and adjusting the temperature of the mixed heat medium to a first preset temperature range; In the temperature-raising and melting process, the mixed heat medium after the temperature adjustment is used as a new heat medium for temperature-raising and melting.

7. The melt crystallization method according to claim 6, characterized in that The following steps are also included: During the temperature rising and melting process, heat is transferred to the outside, so that the inside of the melt crystallization system is in a thermal equilibrium state during the melt crystallization and temperature rising and melting processes.

8. The melt crystallization method according to claim 7, characterized in that The following steps are also included: During the melt crystallization process, the temperatures of several locations are obtained, and all of the locations are located in a container for storing the heat medium and are arranged sequentially along the height direction; estimating the final temperature of the heat medium storage container after the temperature at each location is balanced according to the temperature; The amount of heat transferred to the outside is adjusted according to the final temperature.

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