Freeze concentration method

Abstract

The invention belongs to the technical field of freeze concentration, and relates to a freeze concentration method which comprises the following steps: combining a plurality of freeze concentration devices with a negative correlation principle between melting points and solute concentration according to a certain mode to form a multi-stage freeze concentration system; by utilizing the low-temperature advantage of the solution obtained during dissolution in each stage of freeze concentration, the energy use of the next stage of freeze concentration in the freezing link is reduced, and the energy use efficiency is improved, so that the freeze concentration effect and efficiency are improved; and meanwhile, the energy utilization efficiency can be further improved by utilizing the heat of the dilute solution raw material and the heat dissipation of the freeze concentration device.

Description

Technical Field

[0001] The invention belongs to the technical field of freeze concentration, and in particular relates to a freeze concentration method. Background Art

[0002] Among the existing freeze concentration methods, there are mainly two types of freeze concentration methods with two different physical principles. The first type: a concentration technology that uses the solid-liquid phase relationship of a substance below the crystallization point (such as using an aqueous solution at the freezing point); for example, when the solvent is water, the concentration is achieved by freezing the water into ice crystals and removing the solvent (water) in a solid form through solid-liquid separation (separation of ice crystals from concentrated solution). The second type: a technical method for freeze concentration that uses the negative correlation between the melting point and the solute content (concentration); that is, a method of heating and dissolving the frozen material and collecting dissolved solutions of different concentrations to achieve a concentrated freeze concentration method.

[0003] The first freeze concentration method is a concentration technology that uses the solid-liquid phase relationship between a dilute solution and ice below the freezing point. There are two main methods: suspended crystallization freeze concentration and progressive freeze concentration. The principle of the suspended crystallization freeze concentration method is that when a dilute solution is frozen, the free small ice crystals suspended in the liquid are continuously removed to increase the liquid concentration. The principle of the progressive freeze concentration method is that when a dilute solution is frozen, as the ice layer is generated and grows on the cooling surface, the solute near the solid-liquid interface is removed to the liquid phase side, resulting in a concentration method in which the mass concentration of the solute in the liquid phase gradually increases. The existing freeze concentration methods have complex equipment structures, high equipment costs and production costs, and low efficiency.

[0004] The second freeze concentration method: using the negative correlation between melting point and solute content (concentration), concentration is achieved by heating, dissolving and separating the frozen material. For example, when ice melts naturally, a relatively high concentration solution will be dissolved first. Using this phenomenon, the concentration of the dilute solution can be increased by freezing the solution into a solid and then dissolving it multiple times. This is a freeze concentration method using the natural dissolution of ice. In addition, the natural dissolution of ice is a way of dissolving by heat. Similarly, heating and dissolving ice in other ways will also produce a concentrated solution, achieving freeze concentration. At present, the concentration effect and efficiency of this method are very low.

[0005] The above two freeze concentration methods based on different physical principles have a major problem: the effect and efficiency of freeze concentration are low. In particular, the existing freeze concentration method of heating and dissolving (traditional conventional heating method) has a lower concentration effect and efficiency than the existing method of using the solid-liquid phase relationship of the substance below the crystallization point (such as using the aqueous solution at the freezing point) to achieve concentration.

[0006] The reason that affects the concentration effect and efficiency of the first freeze concentration method is that the physical principle it adopts inevitably leads to the problem of 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 under this physical principle, which is also one of the reasons for the complex structure, high equipment cost and complex operation of existing freeze concentration equipment.

[0007] The second freeze concentration method can solve the solute entrainment problem of the first method, but 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 frozen material and the solid structure inside the frozen material will hinder the heat transfer when it is heated and dissolved, and the separation and outflow of the dissolved solution of the frozen material. These two obstacles seriously affect the concentration effect and efficiency of freeze concentration under this method. Therefore, if these obstacles are ignored and the traditional conventional heating method is used, the effect and efficiency of freeze concentration will be very low.

[0008] The public document (application number CN202411098563.9) adopts a heating method of setting a heat source at a specific position of a solid or solid-liquid mixture frozen from a dilute solution, the public document (application number CN202411098562.4) adopts a method of setting a diversion channel in a solid or solid-liquid mixture frozen from a dilute solution and heating it, the public document (application number CN202411098560.5) adopts a method of crushing and heating a solid or solid-liquid mixture frozen from a dilute solution, etc., which effectively solves the problems of hindering heat transfer and hindering the separation and outflow of dissolved solutions 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, the method of heating and dissolving and retaining the solution in stages greatly improves the effect and efficiency of freeze concentration, making the widespread promotion and use of freeze concentration possible.

[0009] However, since there is a negative correlation between the melting point and the solute content (concentration), the temperature of the dissolved solution obtained by dissolution also has a negative correlation with the concentration. The higher the solution concentration, the lower its temperature. Figure 1The graph is a relationship curve between the mass concentration of alcohol and its melting point (freezing point) (this figure is a reference to public data). For example, when the alcohol concentration is 40wt%, the melting point is around -30℃. If the target concentration of a certain section of the segmented solution is set to an alcohol concentration of 40wt%, the temperature of the dissolved solution can be maintained at around -25℃ (the temperature will change when the receiving conditions and dissolution methods are different); at this time, if this section of solution is frozen at -40℃ or lower and then dissolved, the segmented solution can easily obtain a solution with an alcohol concentration greater than 50wt%, that is, it will take very little energy to obtain a solution with an alcohol concentration greater than 50wt%, which is very effective in improving the effect and efficiency of freeze concentration. On the contrary, if the obtained low-temperature solutions are not handled properly, these low-temperature solutions (such as the aforementioned -25℃ solution) will easily absorb a large amount of energy from the environment and raise the temperature until it is consistent with the ambient temperature. In this case, a lot of energy will be wasted if the next step of freeze concentration is carried out. Summary of the invention

[0010] In order to solve the problems existing in the prior art, the main purpose of the present invention is to propose a freezing concentration method.

[0011] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions: A freeze concentration method comprises combining a plurality of freeze concentration devices using the principle of negative correlation between melting point and solute concentration in a certain manner to form a multi-stage freeze concentration system; in each stage of the multi-stage freeze concentration system, solutions of different concentrations obtained by segmentation are sent to corresponding insulation tanks according to their concentrations; solutions of different concentrations in different insulation tanks are sent to the corresponding freeze concentration device of the next stage for freeze concentration; and the above process is repeated until a solution of the desired target concentration is obtained.

[0012] The freeze concentration method of the present invention utilizes the low temperature advantage of the solution obtained in each stage of freeze concentration, reduces the energy usage in the freezing link of the next stage of freeze concentration, improves the energy usage efficiency, and thus improves the effect and efficiency of freeze concentration.

[0013] As a preferred embodiment of the freeze concentration method of the present invention, in the multi-stage freeze concentration system, the dissolution components in each stage of the freeze concentration device are: a single set of freeze-thaw components, or a combination of multiple sets of freeze-thaw components.

[0014] As a preferred embodiment of the freeze concentration method described in the present invention, the freeze-thaw component utilizes the heat dissipation of the freeze concentration device (such as the heat dissipation of refrigeration equipment) as the heat source during dissolution; the heat dissipation is used directly or the heat is exchanged to an energy medium through a heat exchange device for use.

[0015] As a preferred embodiment of the freeze concentration method described in the present invention, the heat of the dilute solution raw material is used as a heat source for dissolution; the heat is used directly or exchanged to an energy medium through a heat exchange device for use.

[0016] As a preferred embodiment of the freeze concentration method of the present 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 to reduce the temperature of the dilute solution raw material.

[0017] As a preferred embodiment of the freeze concentration method of the present invention, the target concentration solution produced by freeze concentration is used to perform heat exchange on the dilute solution raw material to reduce the temperature of the dilute solution raw material.

[0018] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution: An application of the above freeze concentration method in the fields of food, cosmetics, biomedicine, petrochemicals, environmental protection treatment, etc.

[0019] The above-mentioned freezing concentration method is applied in the fields of milk, vinegar (including vinegar-containing food, vinegar beverages, condiments, etc.), wine, beverages (such as juice, coffee, tea, soy milk, soy milk, etc.), chemical liquid, Chinese herbal medicine liquid, plant extract, petroleum purification, chemical purification, seawater purification, wastewater treatment, etc.

[0020] An application of the freeze concentration method in the field of freeze concentration and separation and purification of heat-sensitive raw materials.

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

[0022] The beneficial effects of the present invention are as follows: The present invention provides a freeze concentration method, which combines a plurality of freeze concentration devices using the principle of the negative correlation between melting point and solute concentration in a certain way to form a multi-stage freeze concentration system; utilizing the low temperature advantage of the dissolved solution produced in each stage of freeze concentration, reducing the energy usage of the freezing link of the next stage of freeze concentration device, so that the energy usage efficiency is greatly improved, thereby improving the effect and efficiency of freeze concentration; at the same time, 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the following description only describes some preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0024] Figure 1 This is a curve chart showing the relationship between the concentration of alcohol and its melting point (freezing point).

[0025] Figure 2 The present invention is a schematic diagram of a freeze concentration method according to an embodiment of the present invention.

[0026] In the figure, 1: dilute solution, 2: freezing concentration device ①, 3: freezing concentration device ②, 4: freezing concentration device ③, 5: insulation tank ①, 6: insulation tank ②, 7: insulation tank ③, 8: insulation tank ④, 9: insulation tank ⑤, 10: insulation tank ⑥, 11-23, 34-38: valves, 24-33: pumping machine, 39: heat exchanger ①, 40: heat exchanger ②, 41: storage tank ⑦, 42: storage tank ⑧.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0028] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] A freeze concentration method comprises combining a plurality of freeze concentration devices using the principle of negative correlation between melting point and solute concentration in a certain manner to form a multi-stage freeze concentration system; in each stage of freeze concentration in the multi-stage freeze concentration system, solutions of different concentrations obtained by segmentation are sent to corresponding insulation tanks according to different concentrations; solutions of different concentrations in different insulation tanks are sent to corresponding freeze concentration devices of the next stage of freeze concentration for freeze concentration; and the above process is repeated until a solution of a desired target concentration is obtained.

[0030] like Figure 2As shown, the embodiment of the present invention provides a multi-stage freeze concentration method implemented by a combination of three-stage freeze concentration devices. Three groups of freeze concentration devices using the principle of negative correlation between melting point and solute concentration are combined in the manner shown in the figure to achieve efficient and energy-saving freeze concentration. The system for implementing the method of the present invention is composed of three groups of freeze concentration devices, six insulation tanks, a dilute solution tank, a number of valves and a pumping machine. Among them, insulation tank ③7 is a high-concentration target solution storage tank; insulation tank ⑥10 is an ice water retention tank (a solution with extremely low solute content); insulation tank ①5 and insulation tank ②6 and insulation tank ④8 and insulation tank ⑤9 are transfer retention tanks for solutions during three-stage freeze concentration; the numbers 11-23 and 34-38 in the figure are valves (the valve has one inlet direction and two outlet directions) used to close and control the flow direction of the solution; the numbers 25-33 in the figure are pumping machines that provide power for the extraction and flow of the solution. The dilute solution and the low-temperature solution produced by each stage of the freezing concentration device (in the insulation tank ⑥: the solution with extremely low solute content) undergo primary heat exchange in the heat exchanger ①39; the dilute solution that has completed the primary heat exchange and the high-concentration target solution from the insulation tank ③7 undergo secondary heat exchange in the heat exchanger ②40. The storage tank ⑦41 is used to store the low-solute content solution that has completed the heat exchange; the storage tank ⑧42 is used to store the high-concentration target solution that has completed the heat exchange.

[0031] When the method of the embodiment of the present invention is used, the dilute solution 1 is sent to the freezing concentration device ①2 through the valve 11 and the pump 24 for freezing and dissolving, and the dissolved solution is retained in stages through the pump 25 and by controlling the valves 12, 13, and 14. The first target concentration solution is sent to the insulation tank ①5, the second target concentration and the third target concentration solutions are sent to the insulation tank ④8 and the insulation tank ⑤9 respectively, and the solution with extremely low solute content (temperature below 0°C) is sent to the insulation tank ⑥10. The first target concentration solution is sent from the insulation tank ①5 to the freeze concentration device ②3 through the valve 15 and the pump 26 for freezing and dissolving. The first target concentration solution of the second stage freeze concentration is sent to the insulation tank ②6 through the pump 27, valves 16, 17, 18, and the second target concentration solution is sent to the insulation tank ①5. The third target concentration and the fourth target solution are sent to the insulation tank ④8 and the insulation tank ⑤9 respectively. The solution with extremely low solute content (temperature below 0°C) is sent to the insulation tank ⑥10. The solution in the insulation tank ②6 is sent to the freezing concentration device ③4 through valve 19 and pump 28 for freezing and dissolving; the first target concentration (i.e., the high concentration target of this freezing concentration) is sent to the high concentration target insulation tank ③7 for storage through pump 29, valves 20, 21, and 22, the second target concentration solution is sent to the insulation tank ②6, the third target concentration and the fourth target concentration solution are sent to the insulation tank ④8 and the insulation tank ⑤9 respectively, and the solution with extremely low solute content (temperature below 0°C) is sent to the insulation tank ⑥10. The solution concentrations of the insulation tanks ④8 and ⑤9 are relatively low, and are sent to the freezing concentration device ①2 through valve 23 and pump 30 for freezing and dissolving, and the segmented process is as described above. The solutions in the insulation tanks ①5 and ②6 are sent to the freezing concentration device ②3 and the freezing concentration device ③4 respectively for freezing and dissolving, and the segmented process is as described above. The solutions with extremely low solute content (temperature below 0°C) produced by each stage of the freezing concentration device are sent to the insulation tank ⑥10, and the solutions that meet the high concentration target are retained in the insulation tank ③7.

[0032] The dilute solution 1 is sent to the heat exchanger ①39 through the directional valve 11 and the pump 24, and undergoes a primary heat exchange with a solution with an extremely low solute content (temperature below 0°C) sent from the insulation tank ⑥10 to the heat exchanger ①39 through the pump 31; the dilute solution that has completed the primary heat exchange is sent to the heat exchanger ②40, and undergoes a secondary heat exchange with a high-concentration target solution sent from the insulation tank ③7 to the heat exchanger ②40 through the pump 33; the dilute solution that has completed the heat exchange is sent to the freeze concentration device ①2 for freezing and dissolving, and its segmented process and each level of freeze concentration process are as described above; the solution with an extremely low solute content that has completed the heat exchange is sent to the storage tank ⑦41 or discharged; the high-concentration target solution that has completed the heat exchange is sent to the storage tank ⑧42 for retention.

[0033] For the solutions in the insulation tank ④8 and the insulation tank ⑤9 of this embodiment, another one-stage or multi-stage freezing concentration device can also be independently set to perform freezing concentration, and the combination method of the multi-stage freezing concentration is as described above.

[0034] This embodiment uses a three-stage freeze concentration device for multi-stage freeze concentration. It is also possible to set up more stages of freeze concentration devices according to the aforementioned combination principle to perform more stages of freeze concentration.

[0035] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A freeze concentration method, characterized in that: A multi-stage freeze concentration system is formed by combining several freeze concentration devices that use the principle of the negative correlation between melting point and solute concentration. In each stage of the multi-stage freeze concentration system, solutions of different concentrations obtained in segments are sent to corresponding insulation tanks according to their concentrations. Solutions of different concentrations in different insulation tanks are sent to the corresponding freeze concentration device of 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-thaw system, the thawing components in each stage of the freeze-thaw device are: a single set of freeze-thaw components, or a combination of multiple sets of freeze-thaw components.

3. The freeze concentration method according to claim 1, characterized in that The heat dissipated by the refrigeration equipment is used as the heat source for dissolution; the heat dissipated is used directly or the heat is exchanged to an energy medium through a heat exchange device for use.

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 for dissolution; the heat is used directly or exchanged to an energy medium through a heat exchange device for use.

5. The freeze concentration method according to claim 1, characterized in that: 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 to reduce 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 to reduce the temperature of the dilute solution raw material.

7. Application of the freezing concentration device according to any one of claims 1 to 6 in the fields of food, cosmetics, biomedicine, petrochemical industry, and environmental protection treatment.

8. Application of the freezing concentration device according to any one of claims 1 to 6 in the fields of milk, wine, vinegar, beverages, chemical liquids, Chinese herbal medicine liquids, plant extracts, petroleum purification, chemical purification, seawater purification, and wastewater treatment.

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