A freeze concentration method

Abstract

The present invention belongs to the technical field of freeze concentration, and relates to a freeze concentration method. A plurality of freeze concentration devices based on the principle of negative correlation between melting point and solute concentration are combined in a certain manner to form a multi-stage freeze concentration system. By utilizing the low-temperature advantage of the solution obtained during the dissolution of each stage of freeze concentration, the energy consumption in the freezing process of the next stage of freeze concentration is reduced, and the energy utilization efficiency is improved, thereby enhancing the effect and efficiency of freeze concentration. At the same time, by using 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.

Description

Technical Field

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

[0002] In existing freeze concentration methods, there are mainly two major types of freeze concentration methods based on different physical principles. The first type: a concentration technique achieved by utilizing the solid-liquid phase relationship of a substance below its crystallization point (such as the freezing point of an aqueous solution); for example, when the solvent is water, the solvent (water) is removed in a solid form by freezing water into ice crystals and separating the solid-liquid (ice crystals and concentrated solution), thereby achieving a freeze concentration method for concentration. The second type: a technical method for freeze concentration achieved by utilizing 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 the dissolved solutions with different concentrations to achieve freeze concentration.

[0003] The first freeze concentration method: a concentration technique achieved by utilizing the solid-liquid phase relationship between a dilute solution and ice below the freezing point. There are mainly two methods: the suspension crystallization freeze concentration method and the progressive freeze concentration method. The principle of the suspension crystallization freeze concentration method is: when freezing a dilute solution, continuously removing the free small ice crystals suspended in the liquid to increase the liquid concentration. The principle of the progressive freeze concentration method is: when freezing a dilute solution, as the ice layer forms and grows on the cooling surface, the solute near the solid-liquid interface is excluded to the liquid phase side, resulting in a gradual increase in the solute mass concentration in the liquid phase. The equipment structures of existing freeze concentration methods are complex, the equipment costs and production costs are high, and the efficiency is not high.

[0004] The second freeze concentration method: utilizing the negative correlation between the melting point and the solute content (concentration), and achieving concentration by heating and dissolving and separating the frozen material. For example, when an ice body naturally dissolves, it will first dissolve out a solution with a relatively high concentration. Utilizing this phenomenon, the concentration of a dilute solution can be increased by freezing the solution into a solid multiple times and then dissolving it, which is a freeze concentration method through the natural dissolution of the ice body. In addition, the natural dissolution of the ice body is a way of heat dissolution. Similarly, using other ways of heating and dissolving the ice body will also obtain a concentrated solution to achieve freeze concentration. Currently, the concentration effect and efficiency under this method are very low.

[0005] Both of the above freeze concentration methods based on different physical principles have a major problem: the freeze concentration effect and efficiency are low. Especially for the existing freeze concentration method of heating and dissolving (traditional conventional heating method), its freeze concentration effect and efficiency are lower than those of the existing method of achieving concentration by utilizing the solid-liquid phase relationship of a substance below its crystallization point (such as the freezing point of an aqueous solution).

[0006] The reasons affecting the concentration effect and efficiency of the first freeze concentration method are as follows: 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 the entrainment of the formed ice crystals are extremely important for the success of the application of freeze concentration under this physical principle, and are also one of the reasons for the complex structure of existing freeze concentration equipment, high equipment cost, and complex operation.

[0007] The second freeze concentration method can solve the problem of solute entrainment in the first method. However, there are also factors affecting the concentration effect and efficiency of the second freeze concentration method: factors such as 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 will hinder the heat transfer during its heating and dissolution, and the separation and outflow of the dissolved solution of the freezing material. These two aspects of hindering factors seriously affect the concentration effect and efficiency of freeze concentration under this method. Therefore, if these aforementioned hindering factors are ignored and a traditional conventional heating method is adopted, the concentration effect and efficiency of freeze concentration will be very low.

[0008] The published document (application number CN202411098563.9) adopts a heating method of setting a heat source at a specific orientation of the solid or solid-liquid mixture formed by freezing a dilute solution, the published document (application number CN202411098562.4) adopts a method of setting a diversion channel in the solid or solid-liquid mixture formed by freezing a dilute solution and heating, the published document (application number CN202411098560.5) adopts a method of crushing and heating the solid or solid-liquid mixture formed by freezing a dilute solution, etc., effectively solving the problems of hindering heat transfer and hindering the separation and outflow of the dissolved solution during the heating and dissolution process of the aforementioned freezing material. Utilizing the negative correlation between the melting point of the freezing material and the solute content, through the methods of heating and dissolution and segmentally retaining the solution, the concentration effect and efficiency of freeze concentration have been greatly improved, making the widespread promotion and use of freeze concentration possible.

[0009] However, by utilizing the 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 1It is a relationship curve graph between the mass concentration of alcohol and its melting point (freezing point) (this graph is a publicly cited reference graph). When the alcohol concentration is 40wt%, the melting point is around -30°C. If a certain section of the solution is taken segment by segment and the target concentration is set to 40wt% alcohol concentration, the temperature of the dissolved solution can be maintained at around -25°C (the temperature will change when the receiving conditions and dissolution methods are different); at this time, if this section of the solution is frozen to -40°C or lower temperature and then dissolved, it is very easy to obtain a solution with an alcohol concentration greater than 50wt% by segmentally taking the solution, that is, a solution with an alcohol concentration greater than 50wt% can be obtained with very little energy, which has a very obvious effect on improving the effect and efficiency of freeze concentration. On the contrary, if the obtained low-temperature solutions of each section are not properly treated, these low-temperature solutions (such as the -25°C solution mentioned above) will easily absorb a large amount of energy from the environment and cause the temperature to rise until it is consistent with the ambient temperature. In this case, a large amount of energy will be wasted when proceeding to the next stage of freeze concentration. Summary of the Invention

[0010] To solve the problems existing in the prior art, the main object of the present invention is to propose a freeze 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:

[0012] A freeze concentration method, in which several freeze concentration devices using the principle of negative correlation between melting point and solute concentration are combined in a certain way to form a multi-stage freeze concentration system; in the freeze concentration of each stage of the multi-stage freeze concentration system, the different concentration solutions obtained segment by segment are sent into the corresponding heat preservation tanks according to different concentrations; the solutions with different concentrations in different heat preservation tanks are sent into the corresponding next-stage freeze concentration device for freeze concentration; the above process is repeated until the solution with the required target concentration is obtained.

[0013] The freeze concentration method of the present invention utilizes the low-temperature advantage of the solutions obtained in the freeze concentration of each stage, reduces the energy consumption in the freezing link of the next-stage 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 described in the present invention, among them: in the multi-stage freeze concentration system, the dissolution components in the freeze concentration devices of each stage are: single-group freeze dissolution components, or a combination composed of multiple groups of freeze dissolution components.

[0015] As a preferred embodiment of the freeze concentration method described in the present invention, among them: the freeze dissolution components use the heat dissipation of the freeze concentration device (such as the heat dissipation of the refrigeration equipment) as the heat source during dissolution; the heat dissipation is used directly or after exchanging the heat of the heat dissipation to the energy medium through a heat exchange device.

[0016] As a preferred embodiment of the freeze concentration method described in the present invention, wherein: the heat of the dilute solution raw material is used as the heat source during dissolution; the heat is directly used or used after exchanging the heat to an energy medium through a heat exchange device.

[0017] As a preferred embodiment of the freeze concentration method described in the present invention, wherein: the solid with low solute content generated by freeze concentration or the low-temperature liquid formed by dissolving it is used to exchange heat with the dilute solution raw material to reduce the temperature of the dilute solution raw material.

[0018] As a preferred embodiment of the freeze concentration method described in the present invention, wherein: the target concentration solution generated by freeze concentration is used to exchange heat with the dilute solution raw material to reduce the temperature of the dilute solution raw material.

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

[0020] An application of the above freeze concentration method in the fields of food, cosmetics, biomedicine, petrochemical industry, environmental protection treatment, etc.

[0021] An application of the above freeze concentration method in the fields of milk, vinegar (including vinegar-containing foods, vinegar beverages, seasonings, etc.), wines, beverages (such as fruit juices, coffee, tea, soy milk, soybean milk, etc.), chemical liquid medicines, Chinese herbal liquid medicines, plant extracts, petroleum purification, chemical purification, seawater purification, wastewater treatment, etc.

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

[0023] An application of the above freeze concentration method in the field of freeze concentration and separation and purification of milk, vinegar (including vinegar-containing foods, vinegar beverages, seasonings, etc.), wines, beverages (such as fruit juices, coffee, tea, soy milk, soybean milk, etc.), chemical liquid medicines, Chinese herbal liquid medicines, plant extracts, seawater purification, petroleum purification, chemical purification, wastewater treatment, etc.

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

[0025] The present invention provides a freeze concentration method, which combines several freeze concentration devices using the principle of negative correlation between melting point and solute concentration in a certain way to form a multi-stage freeze concentration system; by utilizing the low-temperature advantage of the dissolved solution generated in each stage of freeze concentration, the energy consumption in the freezing link of the next-stage freeze concentration device is reduced, and the energy utilization efficiency is greatly improved, thereby 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. Description of the Drawings

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, only some preferred embodiments of the present invention are described below. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the structures shown in these drawings.

[0027] Figure 1 It is a curve graph showing the relationship between the concentration of alcohol and its melting point (freezing point).

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

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

[0030] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. Specific Embodiments

[0031] The following will clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0032] A freeze concentration method combines several freeze concentration devices that utilize the principle of the negative correlation between the melting point and the solute concentration in a certain way to form a multi - stage freeze concentration system; in each stage of freeze concentration in the multi - stage freeze concentration system, the different - concentration solutions obtained in segments are sent into the corresponding heat preservation tanks according to their concentrations; the solutions with different concentrations in different heat preservation tanks are sent into the freeze concentration devices of the corresponding next - stage freeze concentration for freeze concentration; the above process is repeated until a solution with the required target concentration is obtained.

[0033] Such as Figure 2As shown, an embodiment of the present invention provides a multi-stage freeze concentration method implemented by combining three-stage freeze concentration devices. Three freeze concentration devices that utilize the principle of the 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. A system for implementing the method of the present invention is composed of three freeze concentration devices, six heat preservation tanks, a dilute solution tank, several valves, and a liquid extraction pump. Among them, the heat preservation tank ③7 is a storage tank for high-concentration target solution; the heat preservation tank ⑥10 is an ice water retention tank (solution with extremely low solute content); the heat preservation tanks ①5, ②6, ④8, and ⑤9 are transfer and retention tanks for the solution during three-stage freeze concentration; the reference numerals 11-23 and 34-38 in the figure are valves (the valve has one inlet direction and two outlet directions), which are used to close and control the flow direction of the solution; the reference numerals 25-33 in the figure are liquid extraction pumps, which provide power for the extraction and flow of the solution. The dilute solution and the low-temperature solution generated by each stage of the freeze concentration device (in the heat preservation tank ⑥: solution with extremely low solute content) perform 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 heat preservation tank ③7 perform secondary heat exchange in the heat exchanger ②40. The storage tank ⑦41 is used for storing the solution with low solute content that has completed heat exchange; the storage tank ⑧42 is used for storing the high-concentration target solution that has completed heat exchange.

[0034] When the method according to the embodiment of the present invention is in use, the dilute solution 1 is sent into the freeze concentration device ①2 through the valve 11 and the liquid extractor 24 for freezing and dissolution, and then through the liquid extractor 25. By controlling the valves 12, 13, and 14, the dissolved solution is taken in segments. The first target concentration solution is sent into the heat preservation tank ①5, the second target concentration solution and the third target concentration solution are respectively sent into the heat preservation tank ④8 and the heat preservation tank ⑤9, and the solution with extremely low solute content (temperature lower than 0 °C) is sent into the heat preservation tank ⑥10. The first target concentration solution is sent from the heat preservation tank ①5 through the valve 15 and the liquid extractor 26 into the freeze concentration device ②3 for freezing and dissolution, and then through the liquid extractor 27, valves 16, 17, and 18, the first target concentration solution after the second-stage freeze concentration is sent into the heat preservation tank ②6, the second target concentration solution is sent into the heat preservation tank ①5, the third target concentration solution and the fourth target solution are respectively sent into the heat preservation tank ④8 and the heat preservation tank ⑤9, and the solution with extremely low solute content (temperature lower than 0 °C) is sent into the heat preservation tank ⑥10. The solution in the heat preservation tank ②6 is sent into the freeze concentration device ③4 through the valve 19 and the liquid extractor 28 for freezing and dissolution; through the liquid extractor 29, valves 20, 21, and 22, the first target concentration (i.e., the high-concentration target of this freeze concentration) is sent into the high-concentration target heat preservation tank ③7 for standby, the second target concentration solution is sent into the heat preservation tank ②6, the third target concentration solution and the fourth target concentration solution are respectively sent into the heat preservation tank ④8 and the heat preservation tank ⑤9, and the solution with extremely low solute content (temperature lower than 0 °C) is sent into the heat preservation tank ⑥10. The solutions in the heat preservation tanks ④8 and ⑤9 have relatively low concentrations and are respectively sent into the freeze concentration device ①2 through the valve 23 and the liquid extractor 30 for freezing and dissolution, and their segmented processes are as described above. The solutions in the heat preservation tanks ①5 and ②6 are respectively sent into the freeze concentration device ②3 and the freeze concentration device ③4 for freezing and dissolution, and their segmented processes are as described above. The solutions with extremely low solute content (temperature lower than 0 °C) generated by each stage of the freeze concentration device are sent into the heat preservation tank ⑥10, and the solutions meeting the high-concentration target are retained in the heat preservation tank ③7.

[0035] The dilute solution 1 is sent into the heat exchanger ①39 through the direction valve 11 and the liquid extractor 24, and performs a primary heat exchange with the solution with extremely low solute content (temperature lower than 0 °C) sent into the heat exchanger ①39 from the heat preservation tank ⑥10 through the liquid extractor 31; the dilute solution after the primary heat exchange is sent into the heat exchanger ②40 and performs a secondary heat exchange with the high-concentration target solution sent into the heat exchanger ②40 from the heat preservation tank ③7 through the liquid extractor 33; the dilute solution after the heat exchange is sent into the freeze concentration device ①2 for freezing and dissolution, and its segmented process and each stage of the freeze concentration process are as described above; the solution with extremely low solute content after the heat exchange is sent into the storage tank ⑦41 or discharged; the high-concentration target solution after the heat exchange is sent into the storage tank ⑧42 for retention.

[0036] For the solutions in the heat preservation tank ④8 and the heat preservation tank ⑤9 in this embodiment, another one - level or multi - level freeze - concentration device can also be independently set up for freeze - concentration, and the combination mode of its multi - level freeze - concentration is as described above.

[0037] This embodiment adopts multi - level freeze - concentration with a three - level freeze - concentration device. According to the above - mentioned combination principle, a freeze - concentration device with more levels can also be set up for more - level freeze - concentration.

[0038] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made by using the content of the specification of the present invention under the inventive concept of the present invention, or any direct / indirect application in other related technical fields is 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 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, the different concentration solutions obtained in segments are fed into corresponding heat preservation tanks according to their different concentrations. The solutions with different concentrations in different heat preservation tanks are fed into the corresponding next-stage freeze concentration device for freeze concentration. The above process is repeated until a solution with the desired target concentration is obtained.

2. The freeze concentration method according to claim 1, wherein In the multi-stage freeze concentration system, the dissolution component in each stage of the freeze concentration device is: a single-group freeze dissolution component, or a combination composed of multiple groups of freeze dissolution components.

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

5. The freeze concentration method according to claim 4, wherein The solid with a low solute content generated by freeze concentration or the low-temperature liquid formed by dissolving it is used to exchange heat with the dilute solution raw material to lower the temperature of the dilute solution raw material.

6. The freeze concentration method according to claim 4, wherein, The target concentration solution generated by freeze concentration is used to exchange heat with the dilute solution raw material to lower the temperature of the dilute solution raw material.

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

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