Freeze concentration method

Abstract

The present invention relates to the technical field of freeze concentration, and relates to a freeze concentration method. A plurality of freeze concentration devices, each operating on a principle of a negative correlation between a melting point and a solute concentration, are combined in a certain manner to form a multi-stage freeze concentration system. By utilizing the low-temperature advantage of a solution obtained upon melting of each freeze concentration stage, energy consumption in a freezing step of a subsequent stage of freeze concentration is reduced, and the energy use efficiency is improved, thereby enhancing the effect and efficiency of freeze concentration. Additionally, by utilizing heat from a dilute solution raw material itself and heat dissipation from the freeze concentration devices, the energy utilization efficiency is further improved.

Description

A method for freeze concentration Technical Field

[0001] This invention belongs to the field of freeze concentration technology, specifically a freeze concentration method. Background Technology

[0002] There are two main types of existing freeze concentration methods, based on different physical principles. The first type utilizes the solid-liquid phase relationship of a substance below its crystallization point (e.g., using aqueous solutions below their freezing point) to achieve concentration. For example, when the solvent is water, the water is frozen into ice crystals, and the solvent (water) is removed as a solid through solid-liquid separation (separation of the ice crystals from the concentrated solution). The second type utilizes the negative correlation between melting point and solute content (concentration) to achieve freeze concentration. This involves heating and dissolving the frozen material, collecting solutions of different concentrations, and then concentrating the solution.

[0003] The first type of freeze concentration method utilizes the solid-liquid phase relationship between a dilute solution and ice below its freezing point to achieve concentration. It mainly includes two methods: suspension crystallization freeze concentration and progressive freeze concentration. The principle of suspension crystallization freeze concentration is that during the freezing of a dilute solution, free small ice crystals suspended in the liquid are continuously removed, increasing the liquid concentration. The principle of progressive freeze concentration is that during the freezing of a dilute solution, as the ice layer forms and grows on the cooling surface, the solute near the solid-liquid interface is removed to the liquid phase, leading to a gradual increase in the solute concentration in the liquid phase. Existing freeze concentration methods involve complex equipment structures, high equipment and production costs, and low efficiency.

[0004] The second method of freeze concentration utilizes the negative correlation between melting point and solute content (concentration). Concentration is achieved by heating and dissolving the frozen material. For example, when ice melts naturally, a relatively concentrated solution is first formed. Utilizing this phenomenon, the concentration of a dilute solution can be increased by repeatedly freezing the solution into a solid and then dissolving it. This is a freeze concentration method based on the natural melting of ice. Alternatively, since the natural melting of ice is a form of thermal dissolution, similarly, heating and dissolving ice in other ways will also yield a concentrated solution, achieving freeze concentration. Currently, the concentration effect and efficiency of this method are very low.

[0005] Both of the above-mentioned freeze concentration methods based on different physical principles suffer from a significant problem: low efficiency and effectiveness. In particular, existing freeze concentration methods based on heating and dissolving (traditional conventional heating methods) achieve lower concentration efficiency and effectiveness compared to existing methods that utilize the solid-liquid phase relationship of substances below their crystallization point (such as using aqueous solutions below their freezing point).

[0006] The reason why the concentration effect and efficiency of the first freeze concentration method are affected is that the physical principle it adopts inevitably leads to solute entrainment during solid-liquid separation. The separation effect of ice crystals and the control of solute loss caused by ice crystal entrainment are extremely important for the successful application of freeze concentration based on this physical principle, and are also one of the reasons for the complex structure, high cost, and complicated operation of existing freeze concentration equipment.

[0007] The second freeze-concentration method can solve the solute entrainment problem of the first method. However, there are factors that affect the concentration effect and efficiency of the second freeze-concentration method: the dense ice layer with low solute content on the cooling surface of the freezing material and the internal solid structure of the freezing material, etc., will hinder the heat transfer during its melting and the separation and outflow of the dissolved solution. These two obstacles seriously affect the concentration effect and efficiency of freeze-concentration under this method. Therefore, if these obstacles are ignored and conventional heating methods are used, the freeze-concentration effect and efficiency will be very low.

[0008] The published documents (application number CN202411098563.9) employ a heating method that sets a heat source at a specific location in a solid or solid-liquid mixture frozen from a dilute solution; the published documents (application number CN202411098562.4) employ a method that sets a flow channel in a solid or solid-liquid mixture frozen from a dilute solution and then heats it; and the published documents (application number CN202411098560.5) employ a method that breaks down and heats a solid or solid-liquid mixture frozen from a dilute solution. These methods effectively solve the problems of hindering heat transfer and hindering the separation and outflow of the dissolved solution that exist in the heating and dissolving process of the aforementioned frozen materials. By utilizing the negative correlation between the melting point of the frozen material and the solute content, and through the methods of heating and dissolving and segmenting the solution, the effect and efficiency of freeze concentration are greatly improved, making the widespread promotion and use of freeze concentration possible.

[0009] However, taking advantage of the negative correlation between melting point and solute content (concentration), the temperature of the dissolved solution also exhibits a negative correlation with its concentration; the higher the concentration, the lower the temperature. Figure 1 shows the relationship between the mass concentration of alcohol and its melting point (freezing point) (this figure is from publicly available data). For example, when the alcohol concentration is 40 wt%, the melting point is around -30℃. If a segment of the fractional solution is set to a target alcohol concentration of 40 wt%, the temperature of the dissolved solution can be maintained at around -25℃ (the temperature will vary depending on the receiving conditions and dissolution method). If this segment of solution is frozen to -40℃ or lower before dissolution, the fractional solution can easily yield a solution with an alcohol concentration greater than 50 wt%, meaning that a solution with an alcohol concentration greater than 50 wt% can be obtained with very little energy. This significantly improves the effect and efficiency of freeze concentration. Conversely, if the obtained low-temperature solutions are not properly processed, these low-temperature solutions (such as the aforementioned -25℃ solution) can easily absorb a large amount of energy from the environment, causing their temperature to rise until it matches the ambient temperature. In this situation, proceeding to the next stage of freeze concentration would waste a lot of energy. Summary of the Invention

[0010] To address the problems existing in the prior art, the main objective of this invention is to propose a freeze concentration method.

[0011] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:

[0012] A freeze concentration method involves combining several freeze concentration devices that utilize the principle of a negative correlation between melting point and solute concentration to form a multi-stage freeze concentration system. In each stage of freeze concentration within the multi-stage system, solutions of different concentrations obtained are fed into corresponding insulated tanks according to their concentration. Solutions of different concentrations in different insulated tanks are then fed into the corresponding next-stage freeze concentration device for further freeze concentration. This process is repeated until a solution of the desired target concentration is obtained.

[0013] The freeze concentration method of the present invention utilizes the low temperature advantage of the solutions obtained in each stage of freeze concentration, reduces the energy used in the freezing process of the next stage of freeze concentration, improves the energy utilization efficiency, and thus enhances the effect and efficiency of freeze concentration.

[0014] As a preferred embodiment of the freeze-concentration method of the present invention, wherein: in the multi-stage freeze-concentration system, the dissolution component in each stage of the freeze-concentration device is: a single set of freeze-dissolution components, or a combination of multiple sets of freeze-dissolution components.

[0015] In a preferred embodiment of the freeze-concentration method described in this invention, the freeze-dissolution component utilizes the heat dissipation of the freeze-concentration device (such as the heat dissipation of a refrigeration unit) as the heat source during dissolution; the heat dissipation is used directly or after the heat dissipation is exchanged to an energy medium through a heat exchange device.

[0016] In a preferred embodiment of the freeze-concentration method described in this invention, the heat of the dilute solution raw material is used as the heat source during dissolution; the heat is used directly or after being exchanged to an energy medium through a heat exchange device.

[0017] In a preferred embodiment of the freeze concentration method described in this invention, the solid with low solute content produced by freeze concentration or the low-temperature liquid dissolved therefrom is used to exchange heat with the dilute solution raw material, thereby reducing the temperature of the dilute solution raw material.

[0018] In a preferred embodiment of the freeze concentration method described in this invention, the target concentration solution generated by freeze concentration is used to exchange heat with the dilute solution raw material, thereby reducing the temperature of the dilute solution raw material.

[0019] To solve the above-mentioned technical problems, according to another aspect of the present invention, the present invention provides the following technical solution:

[0020] The above-mentioned freeze concentration method has applications in the fields of food, cosmetics, biomedicine, petrochemicals, and environmental protection.

[0021] The above-mentioned freeze concentration method has applications in the fields of milk, vinegar (including vinegar-containing foods, vinegar beverages, condiments, etc.), alcoholic beverages, beverages (such as fruit juice, coffee, tea, soy milk, soy milk, etc.), chemical liquids, traditional Chinese medicine liquids, plant extracts, petroleum purification, chemical purification, seawater purification, and wastewater treatment.

[0022] An application of the above-mentioned freeze concentration method in the field of freeze concentration and separation purification of heat-sensitive raw materials.

[0023] The above-mentioned freeze concentration method is applied in the fields of freeze concentration and separation purification of milk, vinegar (including vinegar-containing foods, vinegar beverages, condiments, etc.), alcoholic beverages, beverages (such as fruit juice, coffee, tea, soy milk, soy milk, etc.), chemical liquids, traditional Chinese medicine liquids, plant extracts, seawater purification, petroleum purification, chemical purification, wastewater treatment, etc.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention proposes a freeze concentration method that combines several freeze concentration devices that utilize the principle of the negative correlation between melting point and solute concentration in a certain manner to form a multi-stage freeze concentration system. By utilizing the low-temperature advantage of the dissolved solution produced in each stage of freeze concentration, the energy consumption of the freezing stage of the next freeze concentration device is reduced, thereby greatly improving energy efficiency and thus enhancing the effect and efficiency of freeze concentration. At the same time, by utilizing the heat of the dilute solution raw material itself and the heat dissipation of the freeze concentration device, the energy utilization efficiency can be further improved. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the following description is only some preferred embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0027] Figure 1 shows the relationship between the concentration of alcohol and its melting point (freezing point).

[0028] Figure 2 is a schematic diagram of the process flow of a freeze concentration method according to an embodiment of the present invention.

[0029] In the diagram, 1: dilute solution, 2: freeze concentration device ①, 3: freeze concentration device ②, 4: freeze concentration device ③, 5: insulated tank ①, 6: insulated tank ②, 7: insulated tank ③, 8: insulated tank ④, 9: insulated tank ⑤, 10: insulated tank ⑥, 11-23, 34-38: valves, 24-33: liquid pump, 39: heat exchanger ①, 40: heat exchanger ②, 41: storage tank ⑦, 42: storage tank ⑧.

[0030] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0031] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] A freeze concentration method involves combining several freeze concentration devices that utilize the principle of a negative correlation between melting point and solute concentration to form a multi-stage freeze concentration system. In each stage of freeze concentration within the multi-stage system, solutions of different concentrations obtained are fed into corresponding insulated tanks according to their concentration. The solutions of different concentrations in the different insulated tanks are then fed into the corresponding freeze concentration device for the next stage of freeze concentration. This process is repeated until a solution of the desired target concentration is obtained.

[0033] As shown in Figure 2, this embodiment of the invention provides a multi-stage freeze-concentration method implemented by combining three freeze-concentration devices. Three sets of freeze-concentration devices, based on the principle of a negative correlation between melting point and solute concentration, are combined as shown in the figure to achieve highly efficient and energy-saving freeze-concentration. The system for implementing this invention consists of three sets of freeze-concentration devices, six insulated tanks, a dilute solution tank, several valves, and a pump. Specifically, insulated tank ③7 is a high-concentration target solution storage tank; insulated tank ⑥10 is an ice water extraction tank (for solutions with extremely low solute content); insulated tanks ①5, ②6, ④8, and ⑤9 are intermediate storage tanks for the solution during three-stage freeze-concentration; valves labeled 11-23 and 34-38 (each valve has one inlet direction and two outlet directions) are used to close and control the flow of the solution; pumps labeled 25-33 provide power for the extraction and flow of the solution. The dilute solution and the low-temperature solution (in insulated tank ⑥: a solution with extremely low solute content) generated by the various stages of the freezing and concentration unit undergo a primary heat exchange in heat exchanger ①39; the dilute solution that has completed the primary heat exchange undergoes a secondary heat exchange with the high-concentration target solution from insulated tank ③7 in heat exchanger ②40. Storage tank ⑦41 is used to store the low-solute-content solution that has completed the heat exchange; storage tank ⑧42 is used to store the high-concentration target solution that has completed the heat exchange.

[0034] In the method of this embodiment of the invention, the dilute solution 1 is sent to the freezing and concentration device ①2 through valve 11 and pump 24 for freezing and dissolution. The dissolved solution is collected in stages through pump 25 and by controlling valves 12, 13 and 14. The solution with the first target concentration is sent to the heat preservation tank ①5, the solutions with the second target concentration and the third target concentration are sent to the heat preservation tanks ④8 and ⑤9 respectively, and the solution with extremely low solute content (temperature below 0°C) is sent to the heat preservation tank ⑥10. The first target concentration solution is sent from the insulated tank ①5 through valve 15 and pump 26 into the freeze-concentration unit ②3 for freezing and dissolution. The first target concentration solution of the second stage freeze-concentration is sent to the insulated tank ②6 through pump 27, valves 16, 17 and 18. The second target concentration solution is sent to the insulated tank ①5. The third and fourth target concentration solutions are sent to the insulated tanks ④8 and ⑤9 respectively. The solution with extremely low solute content (temperature below 0℃) is sent to the insulated tank ⑥10. The solution in insulated tank ②6 is fed into the freeze-concentration unit ③4 via valve 19 and pump 28 for freezing and dissolution. The first target concentration (i.e., the high-concentration target of this freeze-concentration) is fed into the high-concentration target insulated tank ③7 via pump 29 and valves 20, 21, and 22 for storage. The second target concentration solution is fed into insulated tank ②6, and the third and fourth target concentration solutions are fed into insulated tanks ④8 and ⑤9 respectively. Solutions with extremely low solute content (temperature below 0℃) are fed into insulated tank ⑥10. The solutions in insulated tanks ④8 and ⑤9 have lower concentrations and are fed into the freeze-concentration unit ①2 via valve 23 and pump 30 for freezing and dissolution, following the segmented process described above. The solutions in insulated tanks ①5 and ②6 are fed into freeze-concentration units ②3 and ③4 respectively for freezing and dissolution, following the segmented process described above. Solutions with extremely low solute content (temperature below 0℃) produced by each stage of the freeze concentration unit are sent to the insulation tank ⑥10, while solutions that meet the high concentration target are stored in the insulation tank ③7.

[0035] Dilute solution 1 is fed into heat exchanger ①39 via directional valve 11 and pump 24, where it undergoes a first-stage heat exchange with a solution (temperature below 0°C) with extremely low solute content, which is fed into heat exchanger ①39 from insulated tank ⑥10 via pump 31. The dilute solution after the first-stage heat exchange is fed into heat exchanger ②40, where it undergoes a second-stage heat exchange with a high-concentration target solution, which is fed into heat exchanger ②40 from insulated tank ③7 via pump 33. The dilute solution after the heat exchange is fed into freeze-concentration unit ①2 for freezing and dissolution, with its segmented process and each stage of freeze-concentration process as described above. The solution with extremely low solute content after the heat exchange is fed into storage tank ⑦41 or discharged. The high-concentration target solution after the heat exchange is fed into storage tank ⑧42 for storage.

[0036] For the solutions in the insulation tanks ④8 and ⑤9 of this embodiment, another one-stage or multi-stage freezing concentration device can also be set up independently for freezing concentration, and the combination of multi-stage freezing concentration is as described above.

[0037] This embodiment uses a three-stage freeze-concentration device for multi-stage freeze-concentration. Alternatively, more stages of freeze-concentration devices can be combined according to the aforementioned combination principle to perform more stages of freeze-concentration.

[0038] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for freeze concentration, characterized in that, A multi-stage freeze concentration system is constructed by combining several freeze concentration devices that utilize the principle of the negative correlation between melting point and solute concentration. In each stage of freeze concentration in the multi-stage freeze concentration system, solutions of different concentrations obtained in each stage are sent to corresponding insulated tanks according to their concentrations. Solutions of different concentrations in different insulated tanks are then sent to the corresponding freeze concentration device in the next stage for freeze concentration. The above process is repeated until a solution of the desired target concentration is obtained.

2. The freeze-concentration method according to claim 1, characterized in that, In the multi-stage freeze-concentration system, the dissolution components in each stage of the freeze-concentration unit are either a single set of freeze-dissolution components or a combination of multiple sets of freeze-dissolution components.

3. The freeze-concentration method according to claim 1, characterized in that, The heat dissipation of the refrigeration equipment is used as the heat source during melting; the heat dissipation is used directly or after the heat dissipation is exchanged into the energy medium through a heat exchange device.

4. The freeze-concentration method according to claim 1, characterized in that, The heat of the dilute solution raw material is used as the heat source during dissolution; the heat is used directly or after being exchanged to an energy medium through a heat exchange device.

5. The freeze-concentration method according to claim 1, characterized in that, By utilizing the solid with low solute content produced by freeze concentration or the low-temperature liquid formed by its dissolution, heat exchange is carried out on the dilute solution raw material to lower the temperature of the dilute solution raw material.

6. The freeze-concentration method according to claim 1, characterized in that, The target concentration solution produced by freeze concentration is used to exchange heat with the dilute solution raw material, thereby reducing the temperature of the dilute solution raw material.

7. The application of the cryogenic concentration apparatus according to any one of claims 1-6 in the fields of food, cosmetics, biopharmaceuticals, petrochemicals, and environmental protection.

8. The application of the freeze concentration apparatus according to any one of claims 1-6 in the fields of milk, wine, vinegar, beverages, chemical liquids, traditional Chinese medicine liquids, plant extracts, petroleum purification, chemical purification, seawater purification, and wastewater treatment.

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