Foam separation apparatus and foam separation method

Abstract

To provide a foam separation apparatus and a foam separation method that are capable of improving the concentration ratio of a separation target substance.SOLUTION: A foam separation apparatus 1 includes: a first separation column 2; a treated liquid supply unit 3 that supplies a treated liquid containing a separation target substance into the first separation column 2; a first foam generation unit 4 that supplies gas into the first separation column 2 and generates foam from the treated liquid in the first separation column 2; a second separation column 5; a treated residual liquid supply unit 6 that supplies the treated liquid remaining in the first separation column 2 into the second separation column 5; and a second foam generation unit 7 that supplies gas into the second separation column 5 at a flow rate greater than that of the gas supplied into the first separation column 2, and generates foam from the treated liquid in the second separation column 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a foam separation apparatus and a foam separation method. [Background technology]

[0002] A foam separation device is known that generates foam (sometimes referred to as foam liquid) in a solution containing a substance to be separated, and separates the substance to be separated by adsorbing it onto the surface of the foam (see, for example, Patent Document 1).

[0003] Foam separators have the advantages of being simple in structure and operation, low in manufacturing and running costs, and low environmental impact. For these reasons, foam separators are used in a variety of fields, including copper flotation, the concentrated removal of toner and oil-based ink dispersed in paper solvents (deinking), the removal of proteins from skin mucus in fish breeding and aquaculture, and for protein separation in the food and pharmaceutical industries.

[0004] In the separation device (foam separation device) described in Patent Document 1, foam is generated in a liquid to be treated that contains organic compounds, and the organic compounds (substances to be separated) are separated by the foam. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-197650 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a conventional foam fractionator such as that described in Patent Document 1, the generated foam contains a large amount of the solvent of the liquid to be treated, so it is not possible to improve the concentration rate of the substance to be separated.

[0007] An object of the present invention is to provide a foam separation apparatus and a foam separation method that can improve the concentration rate of a substance to be separated. [Means for solving the problem]

[0008] The foam separation device of the present invention comprises a first separation tower, a treated liquid supply section that supplies a treated liquid containing a substance to be separated into the first separation tower, a first foam generating section that supplies gas into the first separation tower and generates foam from the treated liquid in the first separation tower, a second separation tower, a treated residual liquid supply section that supplies the treated liquid remaining in the first separation tower into the second separation tower, and a second foam generating section that supplies gas into the second separation tower at a flow rate greater than the flow rate of gas supplied into the first separation tower and generates foam from the treated liquid in the second separation tower.

[0009] According to the present invention, the liquid to be treated remaining in the first separation tower is supplied to the second separation tower, allowing the remaining liquid to be separated in the second separation tower. Furthermore, since the gas is supplied to the second separation tower at a flow rate greater than the flow rate of the gas supplied to the first separation tower, the drying of the foam in the second separation tower is promoted, allowing the solvent of the liquid to be treated contained in the foam to be reduced. Therefore, the concentration rate of the substance to be separated can be improved.

[0010] The foam separation device of the present invention may include a hydrophilic solution supply section that supplies a hydrophilic solution for foam contact into the first separation tower, the first separation tower having a tower section that extends upward and guides the foam upward in the tower section, and the hydrophilic solution supply section supplies the hydrophilic solution into the tower section and causes the hydrophilic solution to flow downward while coming into contact with the foam rising in the tower section.

[0011] According to the present invention, a hydrophilic solution is supplied into the column section of a separation column and allowed to flow downward while coming into contact with the foam rising in the column section, so that the hydrophilic solution washes away the substances to be removed along the path of the foam movement in the column section, thereby concentrating the substances to be separated and improving the removal rate of the substances to be removed from the substances to be separated.

[0012] The foam separation method of the present invention includes the steps of supplying a liquid to be treated containing a substance to be separated into a first separation tower, supplying a gas into the first separation tower and generating foam from the liquid to be treated in the first separation tower, supplying the liquid to be treated remaining in the first separation tower into a second separation tower, and supplying a gas into the second separation tower at a flow rate greater than the flow rate of the gas supplied into the first separation tower and generating foam from the liquid to be treated in the second separation tower.

[0013] According to the present invention, the same effects as those of the foam separation device described above can be obtained. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a foam separation device according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a schematic diagram of a foam separation device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, when directions are indicated, the state in which the foam separation device 1 is positioned as shown in Figure 1 is used as the reference, with the top being the direction of the Z-axis arrow and the bottom being the opposite direction, the left being the direction of the X-axis arrow and the right being the opposite direction, and the front being the direction toward you in Figure 1 parallel to the Y-axis and the rear being the opposite direction. Furthermore, in the second and subsequent embodiments, components having the same configuration and functions as those of the embodiments already described will be given the same numbers as those in those embodiments or will not be shown in the illustrations, and their descriptions will be simplified or omitted.

[0016] [First embodiment] In FIG. 1, a foam fractionation device 1 separates a target substance from a liquid to be treated that contains the target substance. Examples of solvents for the liquid to be treated include water, alcohol, and mixtures thereof. If the target substance is not a surface-active substance, a surfactant can be added to the water to be treated. In addition to proteins, other surface-active substances include phenols, anionic, cationic, and nonionic synthetic surfactants, fatty acids, and polyhydric alcohols, which can themselves be separated as the target substance. On the other hand, surfactants are substances having a hydrophilic group and a lipophilic group, and examples thereof include anionic surfactants such as fatty acid salts, higher alcohol sulfate salts, liquid fatty oil sulfate salts, sulfates of fatty amines and fatty amides, fatty alcohol phosphate salts, sulfone salts of dibasic fatty acid esters, fatty acid amide sulfonates, alkyl allyl sulfonates, and formalin condensed naphthalene sulfonic acid; cationic surfactants such as fatty amines, quaternary ammonium salts, and alkyl pyridinium salts; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters; and amphoteric surfactants, but are not particularly limited thereto.

[0017] The foam fractionation apparatus 1 includes a first separation tower 2, a liquid to be treated supply section 3, a first foam generation section 4, a second separation tower 5, a residual liquid to be treated supply section 6, a second foam generation section 7, and a residual liquid recovery section 8.

[0018] The first separation column 2 is a cylindrical member made of a transparent or translucent material such as glass or plastic, and has a hollow interior. The first separation tower 2 comprises a tower section 21 extending upward, a foam recovery section 22 extending from the upper end of the tower section 21 to the outside of the tower section 21 and recovering foam BL, a gas supply port 23 and a residual liquid recovery port 24 respectively provided at the lower end of the tower section 21, and a treated liquid supply port 25 provided on the side of the tower section 21.

[0019] The liquid to be treated supply unit 3 supplies the liquid to be treated into the first separation tower 2. The liquid to be treated supply unit 3 includes a liquid to be treated storage unit 31 such as a tank for storing the liquid to be treated, a pump 33 connected to the liquid to be treated storage unit 31 via piping 32, and piping 34 connecting the pump 33 to the liquid to be treated supply port 25.

[0020] The first foam generating section 4 supplies gas into the first separation tower 2 and generates foam BL from the liquid to be treated in the first separation tower 2. The first foam generating section 4 includes a gas storage section 41 such as a tank or gas cylinder that stores gas such as nitrogen gas or argon gas, a pump 43 connected to the gas storage section 41 via piping 42, a piping 44 connected to the pump 43 and inserted into the gas supply port 23, and a disperser 45 provided at the end of the piping 44 and arranged in the first separation tower 2. The disperser 45 is composed of a porous filter made of glass, metal, ceramic, plastic, resin, or the like, such as a glass filter, so-called air stone, or wood stone.

[0021] The second separation tower 5 has a configuration similar to that of the first separation tower 2. That is, the second separation tower 5 includes a tower section 51 extending upward, a foam recovery section 52 extending from the upper end of the tower section 51 to the outside of the tower section 51 and recovering foam BL, a gas supply port 53 and a residual liquid recovery port 54 provided at the lower end of the tower section 51, and a residual liquid supply port 55 to be treated provided on the side of the tower section 51.

[0022] The untreated residual liquid supply unit 6 supplies the untreated liquid remaining in the first separation tower 2 into the second separation tower 5. The untreated residual liquid supply unit 6 includes a pipe 61 connected to the residual liquid recovery port 24, a water level adjuster 62 connected to the pipe 61, a untreated residual liquid storage unit 63 such as a tank for storing the untreated liquid connected to the water level adjuster 62, a pump 65 connected to the untreated residual liquid storage unit 63 via a pipe 64, and a pipe 66 connecting the pump 65 to the untreated residual liquid supply port 55.

[0023] The second foam generating section 7 supplies gas into the second separation tower 5 and generates foam BL from the liquid to be treated in the second separation tower 5. The second foam generating section 7 has the same configuration as the first foam generating section 4, and can be explained by replacing the first symbol 4 in the reference numerals of each component of the first foam generating section 4 with 7, so the reference numerals are replaced in this manner and the explanation thereof will be omitted.

[0024] The residual liquid recovery section 8 is equipped with a pipe 81 connected to the residual liquid recovery port 54 of the second separation tower 5 and a water level regulator 82 connected to the pipe 81, and recovers the residual liquid remaining in the second separation tower 5.

[0025] A method for separating the target substance using the foam fractionator 1 described above will now be described. First, the liquid to be treated is supplied from the liquid storage section 31 to the first separation tower 2 by pump 33. Next, gas is supplied from the gas storage section 41 to the first separation tower 2 by pump 43, and the gas is dispersed by disperser 45 and blown into the liquid to be treated in the first separation tower 2. The blown gas then turns into bubbles AB in the liquid to be treated. If the substance to be separated is a surfactant, the substance to be separated is adsorbed to the surface of the bubbles AB, which is the gas-liquid interface. If the substance to be separated is not a surfactant, the substance to be separated is adsorbed to the surfactant adsorbed to the surface of the bubbles AB and moves upward in the solution. Note that, since proteins, which are the substance to be separated in this embodiment, are also surfactants, they adsorb to the surface of the bubbles AB and rise in the liquid to be treated. Then, the bubbles AB become foam BL, separate from the liquid surface FL of the liquid to be treated, and rise. They are guided upward in tower section 21 with the substance to be separated adsorbed thereto, and are collected from foam collection section 22.

[0026] Meanwhile, the liquid to be treated remaining in the first separation tower 2 is recovered by the residual liquid to be treated supply unit 6 and supplied to the second separation tower 5. Then, the second foam generator 7 supplies gas from the gas storage unit 71 into the second separation tower 5 using the pump 73, and the gas is dispersed by the disperser 75 and blown into the liquid to be treated in the second separation tower 5.

[0027] Here, the concentration of the target substances in the liquid to be treated recovered from the first separation tower 2 has been reduced by the separation in the first separation tower 2, and therefore foaming is unlikely to occur even if gas is supplied to the second separation tower 5 at the same flow rate as the gas supplied to the first separation tower 2. Therefore, the second foam generator 7 supplies gas to the second separation tower 5 at a flow rate higher than that supplied to the first separation tower 2, thereby promoting the generation of foam BL in the first separation tower 2. Furthermore, since the increased gas flow rate promotes drying of the foam BL, the concentration rate of the target substances is improved compared to when gas is supplied to the second separation tower 5 at the same flow rate as that supplied to the first separation tower 2. The foam BL then rises while still adsorbing the target substances and is recovered from the foam recovery unit 52. The remaining liquid in the second separation tower 5 is recovered through a water level regulator 82.

[0028] According to the embodiment described above, the liquid to be treated remaining in the first separation tower 2 is supplied to the second separation tower 5, so that the remaining liquid to be treated can be separated in the second separation tower 5. Furthermore, because the gas is supplied to the second separation tower 5 at a flow rate greater than the flow rate of the gas supplied to the first separation tower 2, the drying of the foam BL in the second separation tower 5 is promoted, and the solvent of the liquid to be treated contained in the foam BL can be reduced. Therefore, the concentration rate of the substance to be separated can be improved.

[0029] [Second embodiment] 2, a foam fractionation apparatus 1 concentrates a substance to be separated and removes a substance to be removed. In the present embodiment, as shown in FIG. 2, the foam fractionation apparatus 1 is provided with a hydrophilic solution supply unit 9, and the configuration of the first separation tower 2 is different from that of the first embodiment.

[0030] The first separation tower 2 is equipped with a hydrophilic solution supply port 26. The hydrophilic solution supply port 26 is provided at the upper end of the tower section 21, and the hydrophilic solution for foam contact supplied from the hydrophilic solution supply section 9 flows into the tower section 21.

[0031] The hydrophilic solution supply section 9 is configured to supply the hydrophilic solution for foam contact into the tower section 21 and to cause the hydrophilic solution to flow downward while coming into contact with the foam BL rising in the tower section 21. The hydrophilic solution supply section 9 includes a hydrophilic solution storage section 91 such as a tank for storing a hydrophilic solution, a pump 93 connected to the hydrophilic solution storage section 91 via piping 92, and piping 94 connecting the pump 93 to the hydrophilic solution supply port 26.

[0032] In this embodiment, the hydrophilic solution supply unit 9 supplies deionized water as the hydrophilic solution. The hydrophilic solution may be any hydrophilic solution (containing soluble components), such as a solution containing water. In this embodiment, the liquid to be treated is a protein solution containing proteins as surfactants, and inorganic salts are the substances to be removed, and proteins are separated from the protein solution as the separation target substances. In addition to inorganic salts, the substances to be removed include organic salts and fine particles. Examples of inorganic salts include sodium salts, calcium salts, magnesium salts, silicates, iron compounds, chlorides, and nitrates. Examples of organic salts include substances that dissociate easily and substances with short alkyl chains, such as sodium acetate and acetylsalicylic acid. Examples of fine particles include hydrophilic particles that are smaller than the plateau boundaries in the foam layer (the liquid channels connecting the bubbles in the foam), such as silica and cellulose particles.

[0033] In the foam fractionation apparatus 1 described above, when a hydrophilic solution is supplied from the hydrophilic solution storage section 91 to the first separation tower 2 by the pump 93, the hydrophilic solution flows downward while coming into contact with the foam BL rising in the tower section 21. At this time, proteins contained in the foam BL are irreversibly adsorbed to the interface between the foam BL and the air and do not desorb from the foam BL, whereas inorganic salts contained in the foam BL and in the liquid between the foam BL are washed away by the supplied hydrophilic solution and fall down the tower section 21 together with the hydrophilic solution due to their own weight. As a result, proteins, which are the substances to be separated, are concentrated and inorganic salts are removed, and they are recovered together with the foam BL from the foam recovery section 22. The liquid to be treated remaining in the first separation tower 2 is supplied to the second separation tower 5, where separation is carried out.

[0034] As an example of foam separation using the foam fractionator 1, foam separation was performed on a liquid to be treated, in which 0.05 wt% lactoferrin (a protein) and 0.5 M sodium chloride (an inorganic salt) were dissolved in water, with lactoferrin as the target substance, both when a hydrophilic solution was supplied to the first separation tower 2 and when no hydrophilic solution was supplied. As a result, when water was supplied as the hydrophilic solution, the concentration rate of lactoferrin obtained from the foam BL recovered in the foam recovery section 22 was the same as when no hydrophilic solution was supplied, but the concentration rate of sodium chloride was significantly lower. In other words, while the protein was concentrated, the inorganic salt was removed without being concentrated, resulting in an improved removal rate of the inorganic salt. The concentration rates were calculated using the following formula (1), with lactoferrin and inorganic salt as the target substances: Concentration rate = concentration of target substance in foam liquid ÷ concentration of target substance in supplied treated liquid (1)

[0035] According to the above embodiment, the concentration rate of the separation target substance can be improved, as in the first embodiment. In addition, a hydrophilic solution is supplied into the column section 21 and flows downward while contacting the foam BL rising in the column section 21, so that the hydrophilic solution washes away inorganic salts along the movement path of the foam BL in the column section 21. Therefore, the separation target substance can be concentrated and the removal rate of inorganic salts from the separation target substance can be improved.

[0036] In addition, since the hydrophilic solution supply port 26 is provided at the upper end of the tower section 21, the distance over which the hydrophilic solution flows within the tower section 21 while coming into contact with the foam BL can be made longer, thereby further improving the removal rate of inorganic salts from the substance to be separated.

[0037] As described above, the best configurations, methods, and the like for implementing the present invention have been disclosed in the above description, but the present invention is not limited thereto. That is, although the present invention has been particularly illustrated and described mainly with reference to specific embodiments, those skilled in the art can make various modifications to the above-described embodiments in terms of shape, material, quantity, and other detailed configurations without departing from the scope of the technical idea and purpose of the present invention. Furthermore, the above-disclosed descriptions limiting the shape, material, and the like are provided as examples to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, descriptions using names of components that are free from some or all of the limitations on shape, material, and the like are included in the present invention.

[0038] The foam separation device 1 may be equipped with three or more separation towers, such as the third separation tower, and treated residual liquid supply sections and foam generating sections corresponding to those separation towers.For example, the treated liquid remaining in the second separation tower 5 may be recovered and supplied to the third separation tower, and gas may be supplied to the third separation tower at a flow rate greater than the flow rate of the gas supplied to the second separation tower 5 to generate foam BL.

[0039] The separation towers 2 and 5 may be formed of transparent or translucent materials, or may be formed of opaque materials, or may be formed of metal, ceramic, or the like, and the materials and dimensions such as height and diameter of the separation towers 2 and 5 are not particularly limited. The tower sections 21, 51 may be provided so as to extend upward so as to guide the foam BL upward, and may be provided so as to extend upward at an angle to the vertical direction, for example. The foam collection sections 22, 52 may be extended in any direction from the tower sections 21, 51, for example, they may be extended horizontally from the upper ends of the tower sections 21, 51, or they may be extended above the tower sections 21, 51. The hydrophilic solution supply port 26 may be provided above the liquid surface FL of the liquid to be treated, and may be provided on the side surface of the tower section 21, for example.

[0040] The liquid to be treated supply section 3 may be connected to the lower end of the tower section 21, for example, and the liquid to be treated may be supplied into the tower section 21 from the lower end.

[0041] In the foam generating units 4 and 7, the distributors 45 and 75 may be provided detachably on the pipes 44 and 74. The gas supplied by the foam generators 4 and 7 may or may not be an inert gas.

[0042] The untreated residual liquid supply section 6 may be connected to the lower end of the tower section 51, for example, and the untreated liquid remaining in the first separation tower 2 may be supplied into the tower section 51 from the lower end.

[0043] When supplying the hydrophilic solution into the tower section 21, the hydrophilic solution supply section 9 may pour the hydrophilic solution in to an extent that does not destroy the foam BL, or may drop the hydrophilic solution, or may spray the hydrophilic solution in the form of a mist. When the foam separation apparatus 1 has three or more separation towers, the hydrophilic solution supply unit 9 may be provided for multiple separation towers excluding the most downstream separation tower, and the hydrophilic solution may be supplied to multiple separation towers excluding the most downstream separation tower, or may be provided only for the first separation tower 2. [Explanation of symbols]

[0044] 1...Foam separation device, 2...First separation tower, 3...Liquid to be treated supply section, 4...First foam generation section, 5...Second separation tower, 6...Liquid to be treated residual supply section, 7...Second foam generation section, 8...Residual liquid recovery section, 9...Hydrophilic solution supply section, 21...Tower section, 26...Hydrophilic solution supply port, BL...Foam.

Claims

1. a first separation column; a liquid to be treated supply unit that supplies a liquid to be treated containing a substance to be separated into the first separation tower; a first foam generating section that supplies gas into the first separation tower and generates foam from the liquid to be treated in the first separation tower; A second separation column; a residual liquid supply unit for supplying the liquid to be treated remaining in the first separation tower into the second separation tower; A foam separation device characterized by comprising a second foam generating section that supplies gas into the second separation tower at a flow rate greater than the flow rate of gas supplied into the first separation tower and generates foam from the treated liquid in the second separation tower.

2. a hydrophilic solution supply unit for supplying a hydrophilic solution for foam contact into the first separation tower; The first separation tower includes a tower section extending upward, and the foam is guided upward in the tower section, The foam separation apparatus according to claim 1, characterized in that the hydrophilic solution supply unit supplies the hydrophilic solution into the tower section and causes the hydrophilic solution to flow downward while contacting the foam rising in the tower section.

3. supplying a liquid to be treated containing a substance to be separated into a first separation tower; supplying a gas into the first separation tower to generate foam from the liquid to be treated in the first separation tower; supplying the liquid to be treated remaining in the first separation tower into a second separation tower; A foam separation method characterized by carrying out a step of supplying gas into the second separation tower at a flow rate greater than the flow rate of the gas supplied into the first separation tower, and generating foam from the liquid to be treated in the second separation tower.

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