A freeze concentration method

Abstract

The present invention belongs to the technical field of freeze concentration, and specifically relates to a freeze concentration method, wherein a dilute solution is frozen into a solid or a solid-liquid mixture, so that the surface solid layer in the solution separation outflow direction of the solid or solid-liquid mixture does not form a dense solid layer when the solid or solid-liquid mixture is heated and dissolved, or the density of the surface solid layer in the solution separation outflow direction is smaller than the density of the surface solid layer in other directions; the solution separation outflow direction is determined according to the internal structural characteristics of the dilute solution after being frozen into a solid or a solid-liquid mixture, that is, the direction that allows the solution to be separated and outflowed more easily is set as the solution separation outflow direction when the solid or solid-liquid mixture is heated and dissolved; heat is transferred to the solid or solid-liquid mixture for dissolution, so as to realize the freeze concentration of the dilute solution and improve the efficiency of freeze concentration. The present invention is simple to operate and is convenient for application in the fields of food, cosmetics, biomedicine, environmental protection treatment, etc.

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 type of freeze concentration method: 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: when freezing a dilute solution, 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: when freezing a dilute solution, as the ice layer is generated and grows on the cooling surface, the solute near the solid-liquid interface is excluded 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 type of 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 through 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 leads to the inevitable solute entrainment problem 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. However, there are factors that affect the concentration effect and efficiency of the second freeze concentration method: factors such as the dense ice layer with low solute content formed near 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, as well as the separation and outflow of the dissolved solution of the frozen material. These two hindering factors seriously affect the concentration effect and efficiency of freeze concentration under this method. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a freezing concentration method and device.

[0009] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0010] A freeze concentration method: freezing a dilute solution into a solid or a solid-liquid mixture so that when the solid or solid-liquid mixture is heated and dissolved, the surface solid layer in the solution separation outflow direction does not form a dense solid layer, or the density of the surface solid layer in the solution separation outflow direction is smaller than that of the surface solid layers in other directions; and setting the direction that makes it easier for the solution to be separated and flowed out as the solution separation outflow direction when the solid or solid-liquid mixture is heated and dissolved; transferring heat to the solid or solid-liquid mixture to dissolve it, thereby realizing freeze concentration of the dilute solution and improving the efficiency of freeze concentration.

[0011] As a preferred embodiment of the freeze concentration method described in the present invention, in which: in the step S1, when the solid or solid-liquid mixture is heated and dissolved, the direction of solution separation and outflow is determined according to the internal structural characteristics of the dilute solution after it is frozen into a solid or a solid-liquid mixture, that is, the direction that makes it easier for the solution to be separated and outflowed is set as the direction of solution separation and outflow when the solid or solid-liquid mixture is heated and dissolved.

[0012] As a preferred embodiment of the freeze concentration method of the present invention, in step S2, the heat is transferred to the solid or solid-liquid mixture in the following manner:

[0013] Solids or solid-liquid mixtures naturally dissolve,

[0014] or directly transferring heat to a solid or solid-liquid mixture, wherein one or more heat sources for transferring heat to the ice body may be provided;

[0015] Or a heat source is arranged at a specific position inside or outside the solid or solid-liquid mixture to transfer heat to it, wherein one or more heat sources can be arranged to transfer heat to the ice body.

[0016] As a preferred embodiment of the freeze concentration method described in the present invention, in step S2, the specific orientation is a description of a directional area: from the cooling surface when the dilute solution is frozen into a solid or a solid-liquid mixture, the specific orientation area is the area in the direction of the solid or solid-liquid mixture from the cooling surface away from the cooling surface (except for the solid layer with low solute content adjacent to the cooling surface). This area can be inside or outside the solid or solid-liquid mixture (related to the position of the cooling surface). The shapes of the heat source include: point, line (column), surface (plate), and sphere.

[0017] As a preferred embodiment of the freeze concentration method described in the present invention, in step S2, the heat source is set in a specific orientation, and the heat transfer direction of the heat source is characterized in that when transferring heat to the solid or solid-liquid mixture, the heat is avoided as much as possible from being transferred to the solid layer with low solute content in the solid or solid-liquid mixture first.

[0018] As a preferred embodiment of the freeze concentration method of the present invention, in step S2, the heat source is arranged at a specific position in the following manner:

[0019] Inserting a heat source into the solid or solid-liquid mixture obtained by freezing;

[0020] Or process (e.g. drill out, cut out) the location where the heat source needs to be set on the solid or solid-liquid mixture, and then place (insert) the heat source;

[0021] Or preset the heat source where you need to set the heat source during the freezing process.

[0022] As a preferred embodiment of the freeze concentration method of the present invention, in step S2, after the solid or solid-liquid mixture is heated, the solution is separated and discharged in a manner of natural outflow, negative pressure extraction or centrifugal separation.

[0023] As a preferred embodiment of the freeze concentration method of the present invention, in step S1, a flow guide channel is provided on the solid or solid-liquid mixture obtained by freezing, so as to improve the effect and efficiency of freeze concentration and separation and purification.

[0024] To solve the above technical problem, according to another aspect of the present invention, the present invention provides the following technical solution:

[0025] An application of the above freeze concentration method in the fields of food, cosmetics, biomedicine, environmental protection treatment, etc.

[0026] The freeze concentration method is applied in the fields of milk, wine, beverages (such as juice, coffee, tea, soy milk, soy milk, etc.), chemical liquid, Chinese herbal liquid, plant extract, seawater desalination, wastewater treatment, etc.

[0027] An application of the freeze concentration method in the field of freeze concentration and separation and purification of heat-sensitive raw materials.

[0028] The freeze concentration method is applied in the freeze concentration and separation and purification of milk, wine, beverages (such as juice, coffee, tea, soy milk, soy milk, etc.), chemical liquid, Chinese herbal liquid, plant extract, seawater desalination, wastewater treatment, etc.

[0029] The beneficial effects of the present invention are as follows:

[0030] The present invention proposes a freeze concentration method, wherein a dilute solution is frozen into a solid or a solid-liquid mixture, so that when the solid or solid-liquid mixture is heated and dissolved, the surface solid layer in the solution separation outflow direction does not form a dense solid layer, or the density of the surface solid layer in the solution separation outflow direction is smaller than the density of the surface solid layer in other directions; the solution separation outflow direction is determined according to the internal structural characteristics of the dilute solution after being frozen into a solid or a solid-liquid mixture, that is, the direction that allows the solution to be separated and flowed out more easily is set as the solution separation outflow direction when the solid or solid-liquid mixture is heated and dissolved; heat is transferred to the solid or solid-liquid mixture for dissolution, so as to realize the freeze concentration of the dilute solution and improve the efficiency of freeze concentration. The present invention is simple to operate and is convenient for application in the fields of food, cosmetics, biomedicine, environmental protection treatment, etc. DETAILED DESCRIPTION

[0031] 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.

[0032] The present invention proposes a freeze concentration method, which breaks the traditional freeze concentration thinking, improves the efficiency of freeze concentration and separation and purification, is simple to operate, and is convenient for application in the fields of food, cosmetics, biomedicine, environmental protection treatment, etc.

[0033] The freeze concentration device used to implement the freeze concentration method of the present invention can be, for example, a cylindrical freeze concentration device, which is composed of a cylindrical dilute solution container and a columnar heat source. The columnar heat source is installed at the bottom center of the container, and the columnar heat source is located at the central axis of the cylindrical dilute solution container and its surrounding area. It is optional to set a columnar heat source (heating rod) in this area, or set multiple columnar heat sources (multiple heat source rods). The top of the columnar heat source is flush with the opening of the dilute solution container, and the opening of the device is equipped with a container cover. The container cover is a container cover made of a material with a smaller thermal conductivity than other parts (the outside of the cover is also protected by a heat-insulating material). When the dilute solution is injected into the cylindrical dilute solution container of the device, the container cover is fastened, the device is inverted (the container cover is at the lower end) and placed in a freezing device for freezing. After the dilute solution is frozen into a solid or a solid-liquid mixture, the device is removed from the freezing device, the container cover is opened, and the solid or solid-liquid mixture is heated and dissolved. The solid surface of the container opening is the solution separation outflow surface during dissolution.

[0034] Example 1

[0035] A freeze concentration method for thorny grape wine, taking 3000mL of thorny grape wine with an alcohol content of 14.88%vol and loading it into the above-mentioned cylindrical freeze concentration device, covering and fastening the container cover, and inverting the device (with the container cover at the lower end) and putting it into a freezing device for freezing. The freezing temperature is -45°C. After the thorny grape wine is frozen into a solid, the device is removed from the freezing device, the container cover is opened, and the container opening is kept facing downward. The heat source of this embodiment is a columnar heat source located at the central axis position of the container. Turn on the heating switch, transfer heat to the thorny grape wine solid through the heat source, the solution flows out from the container opening, and the solution is retained in sections and the dissolution status is recorded, see Table 1.

[0036] Table 1 Details of the segmented solution in Example 1

[0037]

[0038] Example 2

[0039] The difference from Example 1 is that before transferring heat to dissolve the solid, a number of holes are inserted into the solid as a guide channel, and then heat is transferred to the wine solid through a heat source, and the dissolution status is recorded, see Table 2.

[0040] Table 2 Details of the segmented solution in Example 2

[0041]

[0042] Comparative Example 1

[0043] The difference from Example 1 is that the container cover is made of the same material (same thermal conductivity) as the other parts of the container, the opening of the container faces upward during freezing, and the opening of the container faces downward as the outlet for the solution when the solid is dissolved during dissolution. In this case, a dense solid layer has been formed on the solid surface in the direction of the solution separation and outflow during dissolution. The dissolution conditions are recorded, see Table 3.

[0044] Table 3 Details of the segmented solution of Comparative Example 1

[0045]

[0046] It can be seen from Examples 1 and 2 that the first section of the receiving solution in Example 1 has an alcohol content of 35.8% vol, accounting for 9.3% by volume, and the alcohol content of this section of the solution is 140.6% higher than the original alcohol content. The first section of the receiving solution in Example 2 has an alcohol content of 38.9% vol, accounting for 9.5% by volume, and the alcohol content of this section of the solution is 161.4% higher than the original alcohol content. It can be seen that when a dilute solution is frozen in a freeze concentration device, the effect of freeze concentration can be improved by setting a diversion channel for the solid.

[0047] It can be seen from Example 1 and Comparative Example 1 that the alcohol content of the first section of the solution received in Example 1 is 35.8%vol, accounting for 9.3% by volume; the alcohol content of the second section is 33.99%vol, accounting for 9.9% by volume; the alcohol content of the third section is 28.99%vol, accounting for 11.9% by volume; the volume of the first three sections of the solution accounts for 31.1%, and the alcohol content is 32.61%vol. In Comparative Example 1, due to the obstruction of the dense solid layer in the outflow direction of the solution, when the heat is transferred to dissolve it, the concentrated solution inside the solid cannot be separated at the first time. After a long period of heating, a large amount of internal concentrated solution flows out together when the dense solid layer on the surface is dissolved out of the channel. Therefore, in Comparative Example 1, the volume of the first section of the solution received accounts for 26.7%, and the alcohol content of the solution is 22.1%vol. When the volume of the solution received in Example 1 accounts for 31.1%, the alcohol content is increased to 32.61%vol, which is 119% higher than the original alcohol content of 14.88%vol. In comparative example 1, when the volume ratio of the receiving solution was 26.7%, the alcohol content increased to 22.1%vol, which was 48.5% higher than the original alcohol content of 14.88%vol. Comparison between the two: the alcohol content increase rate of Example 1 is 245.3% of the alcohol content increase rate of Comparative example 1. Moreover, the alcohol content of the first three sections of Example 1 was increased to 35.61%vol, while the alcohol content of the first section of the comparative example was only increased to 22.1%vol, and the difference in increased alcohol content reached 13.51%vol. It can be seen that the dense solid layer (ice layer) on the surface in the outflow direction of the solution has a very obvious hindering effect on the separation and outflow of the concentrated solution dissolved from the solid.

[0048] In summary, the freeze concentration method described in the present invention freezes the dilute solution so that the dilute solution is frozen into a solid or a solid-liquid mixture in the device, and no dense solid layer is formed on the solid surface layer in the direction of solution separation and outflow (or the density of the solid layer is relatively smaller); the direction that makes it easier for the solution to be separated and outflowed is set as the solution separation and outflow direction when the solid or solid-liquid mixture is heated and dissolved; the effect and efficiency of freeze concentration can be significantly improved.

[0049] 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: The steps include: S1. Freezing a dilute solution into a solid or a solid-liquid mixture so that when the solid or solid-liquid mixture is heated and dissolved, the density of the surface solid layer in the direction of solution separation and outflow is smaller than the density of the surface solid layer in other directions; S2, transferring heat to the solid or solid-liquid mixture to dissolve it, and retaining the solution in sections to obtain solutions of different concentrations; S3. The solution that meets the target concentration is transferred to the next stage; for the solution that does not meet the target concentration, steps S1-S2 are repeated to continue to increase the solution concentration.

2. The freeze concentration method according to claim 1, characterized in that In the step S2, the heat is transferred to the solid or solid-liquid mixture in such a way that the solid or solid-liquid mixture dissolves naturally.

3. The freeze concentration method according to claim 1, characterized in that In the step S2, the method of transferring heat to the solid or the solid-liquid mixture is: directly transferring heat to the solid or the solid-liquid mixture.

4. The freeze concentration method according to claim 1, characterized in that In step S2, the method of transferring heat to the solid or solid-liquid mixture is: a heat source is set at a specific orientation inside or outside the solid or solid-liquid mixture to transfer heat to it, and the specific orientation is a description of a directional area: from the cooling surface when the dilute solution is frozen into a solid or a solid-liquid mixture, the specific orientation area is the area in the direction of leaving the cooling surface from the cooling surface toward the solid or solid-liquid mixture.

5. The freeze concentration method according to claim 4, characterized in that The heat source is set at a specific orientation, and the heat transfer direction of the heat source is characterized in that when transferring heat to the solid or solid-liquid mixture, the heat is avoided as much as possible from being transferred to the solid layer with low solute content in the solid or solid-liquid mixture first.

6. The freeze concentration method according to claim 1, characterized in that: In step S2, heat is transferred to the solid or solid-liquid mixture to dissolve it, and the solution is separated and discharged in a manner of natural outflow, negative pressure extraction or centrifugal separation.

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

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