JP7433751B2 - Fine bubble manufacturing device and fine bubble manufacturing method - Google Patents

Description

The present invention relates to a fine bubble manufacturing apparatus and a fine bubble manufacturing method that can efficiently manufacture fine bubbles, particularly ultra-fine bubbles.

In recent years, so-called fine bubble technology, which utilizes minute bubbles in liquid, has been attracting attention, and has been used in the food and drinking water fields, cleaning fields, medical and pharmaceutical fields, cosmetics fields, agriculture and plant cultivation fields, water treatment fields, Attempts are being made to utilize it in a wide range of technical fields, including chemistry, liquid crystal/semiconductor/solar cell manufacturing, and new functional material manufacturing.

In such fine bubble technology, minute bubbles in liquid are classified into microbubbles, ultrafine bubbles (also called nanobubbles), etc. depending on their size, and the International Organization for Standardization (ISO) Bubbles with a bubble diameter (volume equivalent diameter) of less than 100 μm are defined as fine bubbles, bubbles with a bubble diameter of less than 1 μm are defined as ultra-fine bubbles, and bubbles with a bubble diameter of less than 100 μm and 1 μm or more are defined as microbubbles ( ISO 20480-1:2017).

In addition, as a method for generating fine bubbles, liquid is pressurized into a container at high speed to generate a high-speed swirling liquid flow, and the gas supplied into the container is crushed to generate fine bubbles. For example, see Patent Document 1), and a pressurized dissolution method (for example, Patent Document 2) is known as a typical generation method.

On the other hand, Patent Document 3 discloses that a plurality of triangular prism-like protrusions are provided on the outer peripheral surface of a cylindrical member in order to make the gas contained in the liquid finer and generate ultra-fine bubbles without supplying gas. An ultra-fine bubble generating tool has been proposed in which the liquid is arranged in a spiral manner and is configured so that the liquid that passes while swirling around a cylindrical member collides with a corner located at the tip of a triangular projection.

International Publication 2000/69550 pamphlet Japanese Patent Application Publication No. 2015-181976 Japanese Patent Application Publication No. 2017-80721

By the way, among the typical fine bubble generation methods mentioned above, the pressure dissolution method is generally said to be more suitable for generating fine bubbles (especially ultra-fine bubbles) at a high concentration. There is.

For example, in Patent Document 2, a pressurized liquid in which a gas is dissolved in a liquid under pressure is ejected from a nozzle under low pressure to generate a liquid mainly containing ultra-fine bubbles, and this is circulated and repeatedly processed. It is said that it is possible to continuously generate fine bubble liquid containing a high concentration of fine bubbles (ultra fine bubbles).

However, in the generation method that involves the flow of liquid, there is not only a possibility that foreign matter may be mixed in from the liquid pump, but also it is difficult to apply to liquids with high viscosity, and the liquids that can be applied are limited. Furthermore, it is unavoidable that the equipment configuration becomes large-scale, and it is necessary to secure a liquid flow path including a supply line, and to provide a control mechanism including a liquid pump. There was a limit to how much the structure could be made more compact.

Furthermore, Patent Document 3 describes an example in which ultra-fine bubbles are generated by submerging a cylindrical member in liquid in a container and rotating the cylindrical member using a motor as a drive source.

However, according to such examples, although it is possible to generate ultra-fine bubbles with a compact device configuration, it has not been possible to generate so many ultra-fine bubbles.

The present invention has been made in view of the above circumstances, and provides a fine bubble manufacturing device that can efficiently manufacture fine bubbles, especially ultra-fine bubbles, with a more compact and simple device configuration. The purpose is to provide a manufacturing method.

According to the present invention, the following fine bubble manufacturing apparatus and the like are provided.
1. A cylindrical cover body with a liquid passage hole,
a rotor blade provided inside the cover body, extending along the radial direction from the center side of the cover body, and having a tip close to the inner circumferential surface of the cover body in a non-contact manner;
a liquid flow shearing module having a top plate provided on one end side of the cover body and through which a rotating shaft to which the rotary blade is fixed is rotatably inserted;
An apparatus for producing fine bubbles, comprising: an ultrasonic generation module that applies ultrasonic waves to the liquid flow induced by the liquid flow shearing module.
2. 2. The fine bubble manufacturing apparatus according to 1, wherein the top plate seals one end side of the cover body.
3. 3. The fine bubble manufacturing apparatus according to 1 or 2, wherein the tip of the rotary blade approaches the inner circumferential surface of the cover body with a gap of 0.1 to 0.5 mm.
4. 4. The fine bubble manufacturing apparatus according to any one of 1 to 3, wherein the diameter of the liquid passage hole is 0.01 to 25% of the height of the rotary blade.
5. Any one of 1 to 4, wherein a large number of the liquid passage holes are drilled in a regular arrangement, and the distance between the centers of adjacent liquid passage holes is 1.0 to 5.0 times the diameter of the liquid passage holes. The apparatus for producing fine bubbles according to claim 1.
6. 6. The fine bubble manufacturing apparatus according to any one of 1 to 5, wherein the total area of the liquid passage holes is 12 to 36% of the area of the inner peripheral surface of the cover body.
7. A method for producing fine bubbles using the apparatus for producing fine bubbles according to any one of 1 to 6.
8. The liquid flow shearing module is installed so that the edge of the rotary blade on the top plate side is located within 10 mm vertically above or within 10 mm vertically below the liquid level of the liquid contained in the processing container. 8. The method for producing fine bubbles according to 7, characterized in that the liquid flow shear module and the ultrasonic generation module are operated by immersing the fine bubble in a liquid.
9. 9. The method for producing fine bubbles according to 7 or 8, wherein a gas as a generation source of fine bubbles is brought into contact with the liquid at a gas-liquid interface in a closed environment to induce a liquid flow in the liquid.
10. 10. The method for producing fine bubbles according to 9, wherein the gas is ozone, oxygen, carbon dioxide, ammonia-containing gas, fluorine-containing gas, or nitrogen.

According to the present invention, fine bubbles, particularly ultra-fine bubbles, can be efficiently produced with a more compact and simple device configuration.

FIG. 1 is an explanatory diagram schematically showing a fine bubble manufacturing apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view schematically showing an example of a rotary blade. FIG. 3 is a perspective view schematically showing another example of a rotary blade. 3 is a graph showing the results of Example 1. This is a part other than the motor of the device used in Comparative Example 1. 3 is a graph showing the results of Comparative Example 1.

Embodiments of the present invention will be described below with reference to the drawings.

[Fine bubble manufacturing equipment]
First, a fine bubble manufacturing apparatus according to this embodiment will be described.
An apparatus 1 shown in FIG. 1 as an example of a fine bubble manufacturing apparatus according to the present embodiment is immersed in a liquid Liq contained in a processing container C to induce a liquid flow in the liquid Liq and to It includes a liquid flow shearing module 2 that applies a shearing force to the flow, and an ultrasonic generation module 3 that applies ultrasonic waves to the liquid flow induced by the liquid flow shearing module 2.
Note that in FIG. 1, important parts are shown cut away for the sake of explanation.

In this embodiment, the liquid flow shearing module 2 has a cylindrical cover body 21 in which a liquid passage hole 20 is formed. Inside the cover body 21, a rotor blade 22 extends along the radial direction from the center side of the cover body 21 and has a tip close to the inner peripheral surface of the cover body 21 without contacting the rotary shaft 21. It is designed to rotate around the center. One end side (upper end side) of the cover body 21 is attached to a drive source such as a motor (not shown), and a rotating shaft 23 to which a rotor blade 22 is fixed is attached to one end side (upper end side) of the cover body 21. A top plate 24 is provided which is rotatably inserted.

As shown in FIG. 1, when the liquid flow shearing module 2 configured in this way is immersed in liquid Liq contained in the processing container C, and the rotor blades 22 are rotated at high speed (for example, 800 to 8000 rpm), Due to the suction action, the liquid Liq in the processing container C is drawn into the interior of the cover body 21 from the other end side (lower end side). The liquid Liq drawn into the cover body 21 is ejected from the liquid passage holes 20 formed in the cover body 21 by the rotary blades 22 rotating inside the cover body 21, and the liquid Liq is ejected from the cover body 21. The liquid flow shearing module 2 induces a liquid flow by repeating such suction and ejection.

Further, the rotary blade 22 rotating inside the cover body 21 is formed such that its tip approaches the inner circumferential surface of the cover body 21 without contacting it, and there is a space between the rotor blade 22 and the inner circumferential surface of the cover body 21. The rotor blade 22 is made to rotate with a narrow gap d.
Thereby, the liquid Liq drawn into the inside of the cover body 21 is sheared between the inner peripheral surface of the cover body 21 and the tip of the rotary blade 22, and passes through the liquid passage hole 20 to the outside of the cover body 21. The liquid is pushed out so as to be ejected, and is also sheared when passing through the liquid passage hole 20, making it possible to continuously apply a shearing force to the induced liquid flow. Therefore, such shearing force repeatedly acts on the liquid flow that repeats suction and ejection as described above.
Note that the tip of the rotary blade 22 refers to the part farthest from the center of the rotary shaft 23.

Here, the tip of the rotary blade 22 only needs to be close to the inner circumferential surface of the cover body 21 to the extent that it can shear the liquid Liq between it and the inner circumferential surface of the cover body 21, and the word "proximity" is used here. , shall be used in this sense. In order to obtain stronger shearing force, the tip of the rotor blade 22 is attached to the inner peripheral surface of the cover body 21 with a gap d of preferably 0.1 to 1.0 mm, more preferably 0.1 to 0.5 mm. However, in order to prevent the rotor blade 22 from coming into contact with the cover body 21 when it rotates, take into account the machining accuracy and assembly accuracy of the members, and take appropriate measures to obtain stronger shearing force. can be designed.
Note that "d" in FIG. 1 indicates the shortest distance between the rotary blade 22 and the inner peripheral surface of the cover body 21.

Further, the number of rotary blades 22 is not particularly limited, but it is preferable to provide three or more rotary blades 22 at equal angular intervals so that rotation is stable. In the example shown in FIGS. 1 and 2, four rotary blades 22 formed in a rectangular shape are combined in a cross shape so as to be perpendicular to a plane orthogonal to the rotation axis 23. Fixed.

Further, it is preferable that the rotor blades 22 be formed in a rectangular shape so that the area of the rotor blades 22 can be made as large as possible in the limited space inside the cover body 21 so that more liquid Liq can be pushed out. , the thickness may not be constant. For example, as shown in FIG. 3, the rotary blade 22 may be formed so that the tip side is tapered and the thickness gradually increases toward the rotary shaft 23 side (root side).

Although such a design change is possible for the rotor blades 22, the larger the volume between adjacent rotor blades 22, the more the liquid Liq pushed out by the rotor blades 22 will receive when passing through the liquid passage hole 20. Since the shearing force becomes strong, it is preferable to appropriately design the shearing force in consideration of the balance with this.

The height of the rotary blade 22 (the length from the lower end to the upper end along the direction of the rotating shaft 23) is not particularly limited, but is, for example, 10 to 50 mm.
The rotational diameter of the rotary blade 22 is, for example, 10 to 100 mm, although there is no particular restriction.

The shape of the cover body 21 may be set in consideration of the size of the rotor blade 22. For example, the diameter (outer diameter) is 1.2 to 12.0 mm larger than the rotation diameter of the rotor blade, and the inner diameter is a value that is 0.2 to 2.0 mm larger than the rotational diameter of the rotor, and the height (the length from the lower end to the upper end along the direction of the rotation axis 23) is 1.0 of the height of the rotor. ~1.5 times, and can be configured as a cylindrical member with a thickness of 0.5 to 5.0 mm.
Each member constituting the liquid flow shearing module 2 can be formed using a metal material with excellent corrosion resistance, such as stainless steel.

Further, the diameter of the liquid passage hole 20 formed in the cover body 21 can be appropriately designed so that the liquid Liq pushed out by the rotary blade 22 receives sufficient shearing force when passing through the liquid passage hole 20. . For example, it is preferably 0.01 to 25% of the height of the rotary blade 22, more preferably 5 to 15%.
The diameter of the liquid passage hole 20 is not particularly limited, but is, for example, 0.01 mm to 12.5 mm.

Furthermore, in consideration of workability, the liquid passage hole 20 is preferably circular in shape as shown in FIG. 1, but may be elliptical or polygonal such as a triangle or a quadrangle. When the liquid passage hole 20 is formed in an elliptical or polygonal shape, the diameter of the liquid passage hole 20 is the diameter of a circle having the same area as the elliptical or polygonal shape.

Further, in the example shown in FIG. 1, a large number of liquid passage holes 20 are formed in a staggered arrangement, but the invention is not limited thereto. As long as they are arranged regularly, for example, they may be arranged in a grid.

When drilling a large number of liquid passage holes 20, the distance between the centers of adjacent liquid passage holes 20 is preferably 1.0 to 5.0 times the diameter of the liquid passage holes 20, and more preferably 1.5 to 5.0 times the diameter of the liquid passage holes 20. .0 times. If the center-to-center distance between adjacent liquid passage holes 20 is short and the liquid passage holes 20 are arranged too densely, it will not be possible to secure a sufficient surface for shearing the liquid Liq with the tip of the rotary blade 22. Considering this, the total area of the liquid passage holes 20 is preferably 12 to 36% of the area of the inner peripheral surface of the cover body 21.

Note that the top plate 24 may have a configuration in which no opening is provided other than the hole for the rotation shaft 23 to pass through, that is, a configuration in which one end side (upper end side) of the cover body 21 is sealed, or a It is also possible to have one or more openings (holes) in addition to the holes shown in FIG. In the latter case, the total area of the openings is typically 1 to 10% of the area of the top plate 24.

According to this embodiment, ultrasonic waves of preferably 10 to 100 kHz are applied from the ultrasonic generation module 3 to the liquid flow induced by the liquid flow shearing module 2 and repeatedly subjected to shear force. Due to these synergistic effects, it is possible to make the bubbles generated in the liquid more fine, and fine bubbles, especially ultra-fine bubbles, can be efficiently produced.

In the example shown in FIG. 1, the ultrasonic generation module 3 is installed inside the mounting table T on which the processing container C is placed, and the ultrasonic wave generating module 3 is installed inside the mounting table T on which the processing container C is placed. The present invention is not limited to this, as long as it is possible to apply ultrasonic waves. The specific configuration of the ultrasonic generation module 3 is also not particularly limited as long as it can oscillate ultrasonic waves in a desired frequency band.

In this way, the fine bubble manufacturing device according to the present embodiment has a simple device configuration including the liquid flow shearing module 2 and the ultrasonic generation module 3.
Therefore, according to the present embodiment, fine bubbles, particularly ultra-fine bubbles, can be efficiently produced with a more compact and simple device configuration. Furthermore, since this embodiment does not involve the flow of liquid by the liquid pump, there is no risk of foreign matter being mixed in from the liquid pump, and it is applicable to liquids with high viscosity. By forming each member constituting the shearing module 2 using a metal material with excellent corrosion resistance such as stainless steel, it becomes possible to apply it to more types of liquid Liq.

In addition, in response to the demand for scale-up, instead of increasing the size of the device 1, the required number of liquid flow shearing modules 2 and ultrasonic generation modules 3 that apply ultrasonic waves in pairs are installed. By arranging them side by side, it can be easily handled.

[Method for producing fine bubbles]
Next, a method for manufacturing fine bubbles according to the present embodiment will be described using an example using the apparatus 1 shown in FIG. In other words, the method described below is a preferred example of the use of the device 1 shown in FIG.

In this embodiment, first, the processing container C containing the liquid Liq that generates fine bubbles is placed on the mounting table T, and the liquid flow shearing module 2 is slowly lowered from above the processing container C. let While the liquid flow shearing module 2 is gently immersed in the liquid Liq stored in the processing container C, the edge (upper edge) 22a of the rotary blade 22 on the top plate 24 side is vertically above the liquid level Lev. The immersion depth of the liquid flow shearing module 2 is adjusted so that it is within 10 mm or within 10 mm vertically lower.

In this way, adjust the immersion depth of the liquid flow shearing module 2, wait for the liquid level Lev to subside, and when it is confirmed that the upper edge 22a of the rotor blade 22 is in the predetermined position, leave it as it is. Then, the liquid flow shearing module 2 and the ultrasonic generation module 3 are operated.

As a result, the liquid flow as described above is induced in the liquid Liq in the processing container C by the liquid flow shearing module 2, but the rotor blade 22 rotates with the upper edge 22a at the position described above. As a result, the liquid level Lev begins to undulate and becomes wavy or swirly. As a result, the gas present at the gas-liquid interface is taken into the liquid, and the taken-in gas rides the liquid flow and repeats the suction and ejection as described above.

As a result, the gas taken in from the gas-liquid interface is made fine by the repeatedly applied shear force and ultrasonic waves, and fine bubbles (especially ultra-fine bubbles) formed by the gas can be efficiently produced. Therefore, if the above operation is performed in an open environment, air from the atmosphere will be taken in and fine bubbles formed by the air will be produced, but if operated in a closed environment, fine bubbles formed by the desired gas will be produced. Bubbles can be manufactured.

To form a sealed environment, for example, while the liquid flow shearing module 2 is in a state where it can be immersed in the liquid Liq, the processing container C is stored in a closed container into which the rotating shaft 23 is rotatably inserted, or the processing container C is The inside of the processing container C may be sealed with a lid member through which the processing container C is rotatably inserted, or the entire apparatus may be stored together with the processing container C in an airtight container. The thus-formed sealed environment is filled with a desired gas such as ozone, oxygen, carbon dioxide, ammonia-containing gas, fluorine-containing gas, or nitrogen as a fine bubble generation source, and liquid that generates fine bubbles. Fine bubbles formed by a desired gas can be produced by inducing a liquid flow while in contact with Liq at the gas-liquid interface.

As described above, according to the present embodiment, it is possible to produce fine bubbles formed of any desired gas, not just air in the atmosphere. If the liquid is located at a position higher than 10mm in the vertical direction, the liquid level Lev will violently wave, and too much gas will be taken into the liquid, easily forming large bubbles, and small bubbles will be taken into the large bubbles. For this reason, the miniaturization of bubbles is hindered, which is disadvantageous to the generation of ultra-fine bubbles.
Furthermore, if the upper end edge 22a of the rotor blade 22 is located at a position more than 10 mm below the liquid level Lev in the vertical direction, the liquid level Lev will not fluctuate, and too little gas will be taken into the liquid, causing bubbles to form. It becomes difficult to occur.

Therefore, in this embodiment, the upper end edge 22a of the rotary blade 22 is positioned within 10 mm vertically above or within 10 mm vertically below the liquid level Lev of the liquid Liq contained in the processing container C. By immersing the liquid flow shearing module 2 in liquid Liq and operating the liquid flow shearing module 2 and the ultrasonic generation module 3, fine bubbles, particularly ultrafine bubbles, can be efficiently produced.

Hereinafter, the present invention will be explained in more detail by giving specific examples.

[Example 1]
Using the apparatus 1 shown in FIG. 1, the liquid flow shearing module 2 is placed in water (135 mL) contained in a 300 mL beaker so that the upper edge 22a of the rotor blade 22 is located 5 mm below the liquid level Lev in the vertical direction. was immersed in the beaker, the rotor 22 was rotated at 4000 rpm, and the ultrasonic generation module 3 was operated to apply 40 kHz ultrasonic waves to the liquid flow induced in the beaker.
Details of the device 1 are as follows.
・Cover body 21: diameter (outer diameter) 33.6 mm, inner diameter: 31.6 mm, height 17.7 mm, thickness 1.0 mm
・Height of rotor blade 22: 12.7mm
・Rotation diameter of rotor blade 22: 31.2mm
- Gap d between the inner peripheral surface of the cover body 21 and the tip of the rotor blade 22: 0.2 mm
・Diameter of liquid passage hole 20: 1.5mm
- Distance between centers of adjacent liquid holes 20: 2.9 mm
- Ratio of the total area of the liquid passage holes 20 to the area of the inner peripheral surface of the cover body 21: 24%

After 10 minutes, the apparatus 1 was stopped, and the particle size distribution of fine bubbles generated in the liquid was measured. The results are shown in FIG. For the measurement, NanoSight NS300 (manufactured by Malvern Panalytical, "NanoSight" is a registered trademark) was used.
From Example 1, it can be seen that according to the present invention, fine bubbles (ultra fine bubbles) can be produced in large quantities with a more compact and simple device configuration.

[Comparative example 1]
Using an ultra-fine bubble generator manufactured by UFB Sansei Corp. "Motor rotating type UFB Generator" (model number Δ1.5VC, parts of the device other than the motor are shown in Figure 5), 330 mL of the device was placed in a container for the device. Water was added and the device was immersed in a predetermined position where the liquid level was 0.2 cm below the top of the rotor, and the device was rotated at 2540 rpm. After 8 minutes, the apparatus was stopped, and the particle size distribution of fine bubbles generated in the liquid was measured in the same manner as in Example 1. The results are shown in FIG.

A comparison between Example 1 (Figure 4) and Comparative Example 1 (Figure 6) shows that according to the fine bubble manufacturing apparatus and manufacturing method of the present invention, fine bubbles with smaller particle diameters (ultra fine bubbles) can be produced in larger quantities. It turns out that it can be manufactured.

Although the present invention has been described above with reference to preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and that various modifications can be made within the scope of the present invention. .

The present invention is applicable to the food/drinking water field, cleaning field, medical/pharmaceutical field, cosmetics field, agriculture/plant cultivation field, water treatment field, chemical field, liquid crystal/semiconductor/solar cell manufacturing field, new functional material manufacturing field, etc. Can be used in a wide range of technical fields.

1 Equipment (fine bubble manufacturing equipment)
2 Liquid flow shearing module 20 Liquid passage hole 21 Cover body 22 Rotor blade 22a Edge of the rotor blade on the top plate side (upper edge)
23 Rotating shaft 24 Top plate 3 Ultrasonic generation module C Processing container T Mounting table Liq Liquid Lev Liquid level

Claims (10)

A cylindrical cover body with a liquid passage hole,
a rotor blade provided inside the cover body, extending along the radial direction from the center side of the cover body, and having a tip close to the inner circumferential surface of the cover body in a non-contact manner;
a liquid flow shearing module having a top plate provided on one end side of the cover body and through which a rotating shaft to which the rotary blade is fixed is rotatably inserted;
A fine bubble manufacturing apparatus comprising: an ultrasonic generation module that applies ultrasonic waves to the liquid flow induced by the liquid flow shearing module (provided that an ozone gas supply for ejecting ozone gas into the liquid flow) (excluding those who have the means) . The fine bubble manufacturing apparatus according to claim 1, wherein the top plate seals one end side of the cover body. The fine bubble manufacturing apparatus according to claim 1 or 2, wherein the tip of the rotary blade is close to the inner circumferential surface of the cover body with a gap of 0.1 to 0.5 mm. The fine bubble manufacturing apparatus according to any one of claims 1 to 3, wherein the diameter of the liquid passage hole is 0.01 to 25% of the height of the rotary blade. Claims 1 to 4, wherein a large number of the liquid passage holes are formed in a regular arrangement, and the distance between the centers of adjacent liquid passage holes is 1.0 to 5.0 times the diameter of the liquid passage holes. The fine bubble manufacturing device according to any one of the above. The fine bubble manufacturing apparatus according to any one of claims 1 to 5, wherein the total area of the liquid passage holes is 12 to 36% of the area of the inner peripheral surface of the cover body. A method for producing fine bubbles using the apparatus for producing fine bubbles according to any one of claims 1 to 6. The liquid flow shearing module is installed so that the edge of the rotary blade on the top plate side is located within 10 mm vertically above or within 10 mm vertically below the liquid level of the liquid contained in the processing container. 8. The method for producing fine bubbles according to claim 7, wherein the liquid flow shear module and the ultrasonic generation module are operated by being immersed in a liquid. The method for producing fine bubbles according to claim 7 or 8, wherein a liquid flow is induced in the liquid while a gas serving as a generation source of fine bubbles is brought into contact with the liquid at a gas-liquid interface in a closed environment. The method for producing fine bubbles according to claim 9, wherein the gas is ozone, oxygen, carbon dioxide, ammonia-containing gas, fluorine-containing gas, or nitrogen.

Images