A heat exchange system, a melt crystallization system and a melt crystallization method

Abstract

The present application relates to a heat exchange system, a melt crystallization system and a melt crystallization method. 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 temperature raising mechanism is provided on the pipeline between the steam outlet and the heat medium storage container. The heat exchange system further includes a temperature regulating mechanism, and the temperature regulating mechanism includes a heat medium conveying assembly. By adding the flash evaporation device and the temperature raising mechanism in the present application, the dependence on exogenous refrigerant and heat medium is reduced, and the energy consumption and cost are lowered. By adding the temperature regulating mechanism, technical problems such as the decline of temperature control accuracy affecting the purity of the product, the crystal morphology and the production efficiency can be avoided. By adding the heat medium conveying assembly, technical problems such as the decline of temperature control accuracy affecting the purity of the product, the crystal morphology and the production efficiency can be avoided.

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 to-be-purified material according to the melting point differences between 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 and purification. Melt crystallization has low energy consumption (the energy consumption is 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, etc.

[0003] Generally speaking, melt crystallization usually includes crystallization, sweating and melting steps. Crystallization refers to the heat exchange between the to-be-purified material (i.e., liquid molten material) and the externally introduced refrigerant, and the temperature of the to-be-purified material decreases slowly accordingly. During this process, the target component in the to-be-purified material transforms 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 formed "residual liquid" is lower than that in the initial material. The sweating process refers to the heat exchange between the crystal after crystallization and the externally introduced heat medium, and the temperature of the crystal after crystallization gradually rises. During this process, the crystal gradually melts to form "sweat". Melting is the heat exchange between the "sweat" and the externally introduced heat medium 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 the refrigerant and heat medium from the outside to meet the heat demand not only consumes a large amount of energy and increases production costs, but also increases the complexity and instability of production due to the introduced external system. 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 human resources. 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 human resources.

[0006] To implement the above solution, the technical solution of the present invention is as follows:

[0007] 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 raising mechanism for raising 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 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 conveying assembly for uniformly mixing the steam processed by the temperature raising 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.

[0008] 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, so that the refrigerant after heat exchange is converted into steam and liquid. By connecting the steam outlet of the flash evaporation device to the heat medium storage container and adding a temperature raising 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 raising mechanism. The steam processed by the temperature raising mechanism can enter the heat medium storage container through the pipeline between the temperature raising 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 raising mechanism is transferred to the heat medium after heat exchange, so as to use the obtained mixed heat medium as a new heat medium for the subsequent heating and melting process, and use the liquid obtained by the flash evaporation process as a new refrigerant for the subsequent melt crystallization process, reducing the dependence on exogenous refrigerants and heat media, and thus reducing energy consumption and costs; By adding a temperature regulating mechanism, the temperature of the heat medium stored in the heat medium storage container can be regulated 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 conveying assembly, the steam processed by the temperature raising 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 raising 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 of the melt crystallization process caused by poor mixing effect between the steam processed by the temperature raising mechanism and the heat medium after heat exchange, which affect the purity, crystal morphology, and production efficiency of the product.

[0009] Optionally, a plurality of temperature monitors are provided in the heat medium storage container along the height direction.

[0010] 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.

[0011] 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.

[0012] Specifically, by adding a cooler in the present 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 take away 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 heat and cold loads generated during the heating and cooling stages in 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.

[0013] 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.

[0014] Optionally, a plurality of temperature monitors are provided in the melt crystallization device along the height direction.

[0015] 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;

[0016] The steam is heated to obtain heated steam;

[0017] The temperature of the liquid is adjusted to a second preset temperature range;

[0018] 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;

[0019] The heated steam is mixed with the heat medium after heat exchange in the heating and melting process to obtain a mixed heat medium, and the temperature of the mixed heat medium is adjusted to a first preset temperature range;

[0020] During the temperature-raising and melting process, the mixed heat medium after temperature adjustment is used as a new heat medium for temperature-raising and melting.

[0021] Optionally, the melt crystallization method further comprises the following steps:

[0022] During the melt crystallization process, heat is transferred to the outside, so that the interior of the melt crystallization system is in a thermal equilibrium state during the melt crystallization and temperature-raising melting processes.

[0023] Optionally, the melt crystallization method further comprises the following steps:

[0024] During the melt crystallization process, temperatures of a plurality of locations are obtained, all of which are located in a container for storing the heat medium and are arranged sequentially along a height direction;

[0025] estimating the final temperature of the heat medium storage container after the temperatures at various locations are balanced based on the temperature;

[0026] The amount of heat transferred to the outside is adjusted according to the final temperature.

[0027] Specifically, due to the uneven temperature distribution of the heat medium within the heat medium storage container (a stepped distribution with decreasing temperature from top to bottom), using existing technologies to monitor the temperature of the heat medium storage container or the heat medium outlet will result in a significant discrepancy between the actual final temperature after heat balance within the container. This can lead to excessive heat transfer to the outside world, causing the actual final temperature to fall below the monitored temperature. This causes the heat transfer process to oscillate, with the final temperature fluctuating around the first preset temperature range. This not only makes it difficult to accurately control the final temperature, but also increases the cost of heat transfer to the outside world.

[0028] This solution, however, adjusts the heat transferred to the outside world based on the final temperature. This approach, by gradually moving the outside heat exchange temperature toward the estimated final temperature, can significantly reduce oscillations and steadily control the final temperature within the first preset temperature range. For example, the final temperature (i.e., final temperature t) is determined as follows:

[0029] Considering that the heat medium in the heat medium storage container is in a state of gas and liquid coexistence after the temperature increase treatment, and the density and specific heat capacity of each layer (i.e., the monitoring area 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 is derived as follows:

[0030] 1. The total heat before mixing, that is, the sum of the heat of each layer, is shown in formula (a):

[0031] (a);

[0032] In the formula , is the density and specific heat capacity of the steam layer, the values of which are determined by the output parameters of the heating mechanism and do not need to be monitored; , is the density and specific heat capacity of the liquid layer, and the constants do 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;

[0033] 2. The total heat after mixing is shown in Equation (b):

[0034] (b);

[0035] The final temperature is t;

[0036] 3. Heat conservation: From it can be obtained that the final temperature (i.e., the final temperature t) is shown in Equation (c):

[0037] (c);

[0038] That is, the final temperature t is the weighted average of the volume * density * specific heat capacity * temperature of each layer, and the weights are the products of the volume, density, and specific heat capacity of each layer: .

[0039] Where , , and , . Description of the Drawings

[0040] Figure 1 is a schematic structural diagram of the heat exchange system of Example 1;

[0041] Figure 2 is a schematic structural diagram of the heat exchange system of Example 2;

[0042] Figure 3 is a schematic structural diagram of the melt crystallization system of Example 3;

[0043] Figure 4 is a schematic diagram of adjusting the heat transferred to the outside according to the final temperature in Example 4;

[0044] Figure 5 is a schematic diagram of adjusting the heat transferred to the outside in Comparative Example 2.

[0045] Reference Signs

[0046] 1 - Flash device;

[0047] 2 - Refrigerant collection pump;

[0048] 3 - Refrigerant storage container;

[0049] 4 - Heating mechanism;

[0050] 5 - Heat medium storage container;

[0051] 6 - Heat medium mixing pump;

[0052] 7 - Cooler;

[0053] 8 - Melting crystallization equipment;

[0054] 9 - Transfer pump. Detailed implementation manners

[0055] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0056] 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" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements, 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 situations.

[0057] 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 of such features. In addition, the meaning of "and / or" appearing throughout the text is to include three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or the solution that both A and B are satisfied. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions 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.

[0058] 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 component 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.

[0059] 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.

[0060] Another embodiment of the present application further provides a melt crystallization system. The melt crystallization system includes the heat exchange system as described above and a melt crystallization device 8. The melt crystallization device 8 is provided with a cold and heat medium outlet end, and the cold and heat medium outlet end is connected to the liquid inlet.

[0061] Optionally, a plurality of temperature monitors are provided in the melt crystallization device 8 along the height direction.

[0062] Another embodiment of 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;

[0063] The steam is subjected to temperature increasing treatment to obtain heated steam;

[0064] The temperature of the liquid is adjusted to a second preset temperature range;

[0065] In 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;

[0066] 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;

[0067] In the heating and melting process, the mixed heat medium after temperature adjustment is used as a new heat medium for heating and melting.

[0068] In another embodiment, the melt crystallization method further comprises the following steps:

[0069] During the temperature rise and melting process, heat is transferred to the outside world, 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.

[0070] In another embodiment, the melt crystallization method further comprises the following steps:

[0071] 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;

[0072] Estimate the final temperature of the heat medium storage container after the temperature at each location is balanced based on the temperature;

[0073] The heat transferred to the outside is regulated according to the final temperature.

[0074] The present invention is 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. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not to be limited to the specific numerical values exemplified below.

[0075] Embodiment 1:

[0076] See also Figure 1 , Figure 1 Schematic diagram of the structure 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 increasing mechanism 4 and a heat medium storage container 5.

[0077] See also Figure 1 The flash evaporation device 1 is used to flash the refrigerant after heat exchange (i.e., after absorbing heat) during the melt crystallization process, so as to convert the refrigerant after heat exchange into vapor 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 tank, a flash evaporator, etc. Flash tanks, flash evaporators, etc. are existing technologies and will not be described in detail here.

[0078] Please continue reading Figure 1, the refrigerant storage container 3 is used as a place to store the initial refrigerant and the liquid obtained by flashing, so as to use the liquid obtained by flashing as a cooling medium (i.e., 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 flashing device 1.

[0079] Please continue to refer to Figure 1 , the heating mechanism 4 is used as a place to increase the temperature of the steam obtained after being processed by the flashing device 1. The heating mechanism 4 is located on the pipeline between the steam outlet of the flashing device 1 and the heat medium storage container 5. The heating mechanism 4 can adopt a heater, a compressor, etc. Heaters, compressors, etc. are prior arts and will not be elaborated here.

[0080] Please continue to refer to Figure 1 , the heat medium storage container 5 is used as a place to mix the heat medium after heat exchange and the steam obtained after being compressed and processed by the heating mechanism. During the mixing process, the heat of the steam processed by the heating 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 inside 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 initially stored heat medium in the heat medium storage container 5 (i.e., 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, such as 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. Temperature monitors can include, for example, thermometers, pyrometers, etc.

[0081] Please refer to Figure 1 , the heat exchange system further includes a heat medium conveying component for evenly mixing the steam processed by the heating 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. The two 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. A heat medium mixing pump 6 is provided on the heat medium conveying pipeline.

[0082] Specifically, in this embodiment, by adding a heat medium delivery component, the steam processed by the heating mechanism can be evenly mixed with the heat medium stored in the heat medium storage container 5 through the heat medium delivery component and the heat medium mixing pump 6, enhancing the mixing effect between the steam processed by the heating 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 large temperature gradient and decreased temperature control accuracy in the melting and crystallization process caused by poor mixing effect between the steam processed by the heating mechanism 4 and the heat medium after heat exchange, which affect the purity, crystal morphology and production efficiency of the product.

[0083] 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 (i.e., the refrigerant after absorbing heat) in the melting and crystallization process can be flash-evaporated, so that the refrigerant after heat exchange (i.e., the refrigerant after heat exchange in the melting and crystallization process. After melting and 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 steam outlet of the flash evaporation device 1 to the heat medium storage container 5 and adding a heating 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 heating mechanism 4. The steam processed by the heating mechanism can enter the heat medium storage container 5 through the pipeline between the heating mechanism 4 and the heat medium storage container 5 and be mixed with the heat medium after heat exchange stored in the heat medium storage container 5 (i.e., the heat medium after heat exchange in the heating and melting process. After heating and melting, the temperature of the initial heat medium drops to obtain the heat medium after heat exchange). During the mixing process, the heat of the steam processed by the heating mechanism is transferred to the heat medium after heat exchange, so that the obtained mixed heat medium can be used as a new heat medium, and the liquid obtained by flash evaporation is used as the refrigerant in the subsequent melting and crystallization process, reducing the dependence on exogenous refrigerant and heat medium, and thus reducing energy consumption and cost. 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 decreased temperature control accuracy in the melting and 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 heating 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 heating 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, and avoiding technical problems such as large temperature gradient and decreased temperature control accuracy in the melting and crystallization process caused by poor mixing effect between the steam processed by the heating mechanism and the heat medium after heat exchange, which affect the purity, crystal morphology and production efficiency of the product.

[0084] Embodiment 2

[0085] Please refer to Figure 2, The difference between this embodiment and Embodiment 1 lies in 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 the 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.

[0086] Specifically, in this embodiment, by adding a cooler 7, connecting the first end of the cooler 7 to the heat medium outlet end, and connecting the second end of the cooler 7 to the heat medium inlet end, the cooler 7 can cool a part of the mixed heat medium in the heat medium storage container 5 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 heat medium in the heat medium storage container 5, remove the excess heat generated during the heating process, adjust the balance state of the heating and cooling 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.

[0087] Embodiment 3:

[0088] 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.

[0089] 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 precipitates crystals from the to-be-purified material, and realizes the separation of the product through remelting purification. The melt crystallization equipment 8 is provided with a cold and heat medium inlet end and a cold and heat medium outlet end. The cold and heat medium outlet end of the melt crystallization equipment 8 is connected to the cold and heat medium inlet end. The cold and heat medium inlet end of the melt crystallization equipment 8 is connected to the liquid outlet end of the refrigerant storage container 3 and the heat medium outlet end of the heat medium storage container 5. The cold and heat medium outlet end of the melt crystallization equipment 8 is connected to the liquid inlet of the flash evaporation equipment 1 and the heat medium inlet end of the heat medium storage container 5. A transfer pump 9 and a flow regulator (not shown) are provided on the pipeline between the cold and heat 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 cold and heat medium inlet end of the melt crystallization equipment 8 and the heat medium outlet end of the heat 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.

[0090] Embodiment 4:

[0091] Using the melt crystallization system of Example 3 (the heating mechanism 4 uses a compressor, and there are 4 temperature monitors in the heat 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 cyclone falling film crystallizer, and its structure is as shown in Example 2 of CN202210044553.1. The specific steps are as follows:

[0092] Introduce liquid naphthalene with a purity of 96.00 wt% into the melt crystallization equipment 8. Start the transfer pump 9 on the pipeline between the cold and heat medium inlet end of the melt crystallization equipment 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. The lowest temperature in the crystallization stage is set at 60 °C;

[0093] The refrigerant (specifically water with a temperature of 60 °C) absorbs heat and warms up in the melt crystallization equipment and then enters the flash evaporation equipment 1. Set the temperature in the flash evaporation equipment 1 to 60 °C and the pressure to 20 kPa to cause partial refrigerant to flash evaporate to obtain liquid and steam. Adjust the temperature at the liquid outlet of the flash evaporation equipment 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 with a temperature of 76 - 90 °C) cached in the heat medium storage container 5 to obtain a mixed heat medium;

[0094] 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 the 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 equipment 8, turn off the heat medium mixing pump;

[0095] Open the transfer pump 9 on the pipeline between the cold and heat medium inlet end of the melt crystallization equipment 8 and the heat medium storage container 5, and send the new heat medium in the heat medium storage container 5 to the melt crystallization equipment 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;

[0096] During the melt crystallization process, obtain the temperatures of all sites located in the heat medium storage container 5 and arranged in the height direction;

[0097] Estimate the final temperature after the temperature balance at each part of the heat medium storage container 5 based on the temperatures. 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:

[0098] 1. The total heat before mixing, the sum of the heats of each layer is as shown in Equation (a):

[0099] (a);

[0100] 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;

[0101] 2. The total heat after mixing is as shown in Equation (b):

[0102] (b);

[0103] The final temperature is t;

[0104] 3. Heat conservation: From it can be obtained that the final temperature (i.e., the final temperature t) is as shown in Equation (c):

[0105] (c);

[0106] That is, the final temperature is the weighted average of the volume * density * specific heat capacity * temperature of each layer, and the weights are the products of the volume, density, and specific heat capacity of each layer: .

[0107] Among them , , and , ;

[0108] Adjust the heat transferred to the outside according to the final temperature. Specifically, in accordance with Figure 4Adjust the heat transferred to the outside. Among them, the target temperature is 90 °C, T4 refers to the temperature value detected by the temperature detector located at the bottom, and the flow ratio refers to 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. In the attached drawings, the time refers to the time starting from when the heating mechanism starts heating. Exemplarily, 1 min means 1 min after heating;

[0109] After the new heat medium is heat-exchanged, it flows out of the melt crystallization device 8. 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 in the heat medium system due to the flash evaporation of the cooling medium. The remaining part enters the heat medium storage container 5 for caching;

[0110] The purity of the obtained product is detected by gas chromatography. After detection, the purity is 98.83 wt%.

[0111] When producing according to this embodiment, the energy obtained from the outside is the power consumption of the compressor and the amount of circulating water in the cooler. Among them, the cost of the circulating water can be ignored. Therefore, calculated according to the electricity price of 0.52 yuan / kW·h, when producing according to this embodiment, the heat energy consumption cost = power consumption of the compressor * electricity price = 35 kW * 0.52 yuan / kW·h = 18.2 yuan / h.

[0112] Comparative Example 1:

[0113] 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.

[0114] The purity of the obtained product is detected by gas chromatography. After detection, the purity is 98.79 wt%.

[0115] When producing according to this comparative example, the energy obtained from the outside is the steam consumption and the amount of circulating water in the refrigerant heat exchanger. Among them, the cost of the circulating water can be ignored. Therefore, calculated according to the steam price of 200 yuan / t, when producing according to this comparative example, the heat energy consumption cost = steam consumption * steam price = 200 yuan / t * 0.21 t / h = 58 yuan / h.

[0116] As can be seen from the above Example 4 and Comparative Example 1, 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, the present application can perform flash evaporation treatment on the refrigerant after heat exchange (i.e., the refrigerant after absorbing heat) in the melt crystallization process, converting the refrigerant after heat exchange into steam and liquid. By connecting the gas outlet and steam outlet of the flash evaporation device to the heat medium storage container and adding a compressor to 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. 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, so that the obtained mixed heat medium can be used as a new heat medium (i.e., the heat medium), and the liquid obtained by the flash evaporation treatment is used as the cooling medium (i.e., the refrigerant) in the subsequent melt crystallization process, reducing the dependence on exogenous refrigerant and heat medium, thereby reducing energy consumption and cost.

[0117] Comparative Example 2:

[0118] 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 follows Figure 5 shown.

[0119] The purity of the obtained product was detected by gas chromatography. After detection, the purity was 98.80 wt%.

[0120] According to this comparative example for production, the energy obtained from the outside is the steam consumption and the circulating water consumption of the refrigerant heat exchanger.

[0121] As can be seen from the above Example 4 and Comparative Example 2, compared with Comparative Example 2, the circulating water flow rate ratio of Example 4 is reduced by 14%, that is, the circulating water consumption is 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, so that the outside heat exchange temperature gradually approaches the estimated final temperature, the circulating water consumption is reduced, the outside heat transfer cost is reduced, the adjustment times can also be reduced, the oscillation state is reduced, the multiple oscillation-type adjustments are avoided, and the operation cost is reduced.

[0122] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit 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 made 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 melt crystallization system, characterized in that, The molten crystallization system includes 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-raising 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 assembly for uniformly mixing the steam processed by the temperature-raising 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; A number of temperature monitors are provided in the heat medium storage container along the height direction; The heat medium storage container is provided with a heat medium outlet end and a heat medium inlet end. The temperature adjustment 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 that the temperature of the remaining mixed heat medium is adjusted 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; The molten crystallization system further includes a molten crystallization device, and the molten 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; Estimate the final temperature after the temperature balance at each part of the heat medium storage container according to the temperatures at a number of sites obtained by a number of the temperature monitors; According to the final temperature, adjust the flow rate of the circulating water in the cooler so as to adjust the heat transferred to the outside.

2. The melt crystallization system according to claim 1, wherein, 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.

3. A melt crystallization method, the melt crystallization method sequentially includes melt crystallization and heating melting, characterized in that, Perform flash evaporation treatment on the refrigerant after heat exchange in the molten crystallization process to obtain steam and liquid; Perform temperature-raising treatment on the steam to obtain temperature-raised steam; Adjust the temperature of the liquid to a second preset temperature range; In the molten crystallization process, use the liquid after temperature adjustment as a new refrigerant to perform molten crystallization on the material to be purified; Mix the temperature-raised steam with the heat medium after heat exchange in the temperature-raising melting process to obtain a mixed heat medium, and adjust the temperature of the mixed heat medium to a first preset temperature range; In the temperature-raising melting process, use the mixed heat medium after temperature adjustment as a new heat medium to perform temperature-raising melting; In the molten crystallization process, transfer heat to the outside so that the inside of the molten crystallization system is in a heat balance state during the molten crystallization and temperature-raising melting processes; During the molten crystallization process, obtain the temperatures at a number of sites, and all the sites are located in the container for storing the heat medium and are arranged in sequence along the height direction; Estimate the final temperature after the temperature balance at each part of the heat medium storage container according to the temperature; Adjust the heat transferred to the outside according to the final temperature.

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