Bubble forming device and bubble forming method

Abstract

The invention provides a bubble forming apparatus and a bubble forming method. A bubble forming device is provided with a first porous body (11) and a second porous body (12). In the first porous body (11), an array of first through-holes (11a) is formed, and gas is injected from an end of a first surface (S1) of the first through-holes (11a) and fine bubbles (B) are generated at an end of a second surface (S2) that is in contact with the liquid (L). The second porous body (12) has formed therein an array of microbubbles (B) and second through-holes (12a) through which the liquid (L) can pass, and is disposed in the liquid (L) so as to deform the microbubbles (B) grown from the ends of the first surfaces (S1) of the first through-holes (11a). The second porous body (12) is disposed so that the direction of the second through-holes (12a) is the same as the direction of the first through-holes (11a), and a slit (E) through which the microbubbles (B) and the liquid (L) can pass is left between the second porous body (12) and the first porous body (11).

Description

Technical Field

[0001] This invention relates to a bubble forming apparatus and a bubble forming method. Background Technology

[0002] In bubble-forming devices that generate microbubbles, most use liquid pumps to drive liquid flow through mechanical power, utilizing the energy of the liquid flow to miniaturize the bubbles. However, this type of device requires a liquid pump, resulting in high operating costs, a large overall structure, cumbersome operation, and difficulty in avoiding contamination (hereinafter referred to as "contamination") caused by the liquid pump.

[0003] Therefore, bubble-forming devices that do not require liquid pumps have been proposed (e.g., Patent Document 1). Such devices can generate microbubbles in isolation from the external environment, thus promising pollution-free utilization. However, these devices are also dynamic bubble-forming devices that rely on power to drive liquid flow, and therefore, like devices using liquid pumps, they are bulky and cumbersome to operate.

[0004] Patent Document 1: Japanese Patent No. 6755035.

[0005] Therefore, devices for generating microbubbles in a quasi-static manner using sound waves, ultrasound, or high voltage have been proposed. However, these devices remain bulky and cumbersome to operate.

[0006] Furthermore, a static bubble-forming device has been proposed that generates microbubbles without requiring power to drive liquid flow. In this device, microbubbles are generated from a nozzle or porous body with a necking structure. However, in such a device, in order to generate a large number of microbubbles with uniform bubble diameters, it is necessary to implement measures such as adding surfactants to the surface of the nozzle or porous body for hydrophilic treatment, and there is a limit to the reduction of the size of the formed microbubbles, and the size of the microbubbles will also vary. Summary of the Invention

[0007] The present invention was made in view of the above circumstances, and its object is to provide a bubble forming apparatus and a bubble forming method capable of generating a large number of uniformly sized microbubbles without the need for power to drive the flow of liquid.

[0008] To achieve the above objectives, the bubble forming apparatus according to the first aspect of the present invention comprises:

[0009] A first porous body having an arrangement of first through holes, gas being injected from one end of the first through holes and generating microbubbles at the other end in contact with the liquid; and

[0010] The second porous body is formed with an arrangement of microbubbles and second through-holes through which liquid can pass, and is disposed in the liquid to deform the microbubbles growing from the other end of the first through-hole.

[0011] The second porous body is configured to leave a gap between itself and the first porous body, allowing micro-bubbles and liquid to pass through, in the same manner as the first through hole, with the second through hole in the same direction.

[0012] Alternatively, in the arrangement of the first through holes, the shape and size of the cross-sections of each of the first through holes that are orthogonal to their through direction can be uniform, and they can be arranged at a constant interval.

[0013] Alternatively, the first through hole and the second through hole can be arranged at a constant interval.

[0014] The spacing between the first through holes is more than twice the spacing between the second through holes.

[0015] Alternatively, the second porous body described above may be a mesh structure in which the second through-hole is formed by a mesh of mesh fibers.

[0016] Alternatively, the inner wall of the second through hole can be bent or curved when cut with a cross section containing the center line of the second through hole extending in the through direction.

[0017] The cross-sectional shape of the second through hole, as observed along the through direction, is polygonal.

[0018] It may also have an adjustment part that can adjust the size of the aforementioned gap.

[0019] In the bubble formation method according to the second aspect of the present invention,

[0020] Gas is allowed to pass through one end of the first through-holes arranged on the first porous body, generating tiny bubbles at the other end of the first through-holes that are in contact with the liquid.

[0021] A second porous body, which has formed a second through hole through which microbubbles and liquid can pass, is configured in the liquid such that the direction of the second through hole is the same as that of the first through hole, and a gap is left between the second porous body and the first porous body so that microbubbles and liquid can pass through, thereby deforming the microbubbles growing from the other end of the first through hole.

[0022] Invention Effects

[0023] According to the present invention, it is possible to generate a large number of uniformly sized microbubbles without the need for power to drive the liquid flow. Attached Figure Description

[0024] Figure 1AThis is a perspective view showing the overall configuration of the bubble forming apparatus according to an embodiment of the present invention.

[0025] Figure 1B It means Figure 1A A cross-sectional view of the structure of the bubble generating part.

[0026] Figure 2 This is a magnified schematic diagram showing the structure of the bubble-generating part.

[0027] Figure 3 This is a schematic diagram of the mesh structure when viewed along the direction of the second through hole.

[0028] Figure 4A This is a schematic diagram illustrating the process from the formation to the detachment of tiny bubbles.

[0029] Figure 4B This is a second schematic diagram illustrating the process from the generation to the detachment of microbubbles.

[0030] Figure 4C This is the third schematic diagram illustrating the process from the formation to the detachment of microbubbles.

[0031] Figure 5 This is a schematic diagram illustrating the simultaneous formation of multiple tiny bubbles.

[0032] Figure 6 This is a schematic diagram showing the second through hole when viewed from the through direction.

[0033] Figure 7 This is a schematic diagram illustrating the merging of tiny bubbles.

[0034] Figure 8 This is a schematic diagram showing a modified example of the second porous body.

[0035] Figure 9 This is a flowchart illustrating a bubble formation method according to an embodiment of the present invention.

[0036] Figure 10 This is a graph comparing the size and dispersion of the Soder diameter of microbubbles formed by the bubble forming apparatus of Figure 1 with the size and dispersion of the Soder diameter of microbubbles formed by other bubble forming apparatuses.

[0037] Figure 11 This is a graph that compares the mass transfer capacity coefficient of the bubble forming apparatus in Figure 1 with that of other bubble forming apparatuses, relative to the empty tower gas velocity.

[0038] Figure 12 This is a graph that compares the mass transfer capacity coefficient of the bubble forming apparatus in Figure 1 with that of other bubble forming apparatuses, relative to the required power. Detailed Implementation

[0039] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, identical or equivalent parts are labeled with the same reference numerals. Furthermore, in the following embodiments, expressions such as "having," "comprising," or "containing" also include meanings such as "formed by" or "constituting from."

[0040] [Bubble forming device]

[0041] Reference Figure 1A as well as Figure 1B The overall configuration of the bubble forming apparatus 100 according to this embodiment will be described. For example... Figure 1A As shown, the bubble forming apparatus 100 according to this embodiment forms microbubbles B. The bubble forming apparatus 100 includes a bubble generating unit 1, a first container 2, and a second container 3.

[0042] Inside the first container 2, i.e., the first region Ar1 (refer to...) Figure 1B The first container 2 is filled with gas G. The first container 2 is a storage chamber for temporarily storing gas G. Inside the second container 3, i.e., the second region Ar2 (refer to...),... Figure 1B The container is filled with liquid L. The bubble generating part 1 forms the upper surface of the first container 2 and is part of the bottom surface of the second container 3.

[0043] The bubble generating unit 1 is positioned at the boundary between the first region Ar1 and the second region Ar2, defining their boundary. The bubble generating unit 1 draws in gas G from the first container 2 from its lower surface and discharges tiny bubbles B into the liquid L of the second container 3.

[0044] like Figure 1A As shown, the bubble forming apparatus 100 includes a gas supply source 4, a gas supply pipe 5, a regulator 6, a flow meter 7, a pressure gauge 8, and a control unit 10. The gas supply source 4 is the supply source of gas G, which becomes the source of microbubbles B in this embodiment. The gas supply pipe 5 supplies gas G from the gas supply source 4 to the first region Ar1 within the first container 2.

[0045] Regulator 6 adjusts the amount of gas G supplied from gas supply source 4 through gas supply pipe 5. Flow meter 7 measures the flow rate of gas G supplied from gas supply source 4 through gas supply pipe 5. Pressure gauge 8 measures the pressure of gas G supplied from gas supply source 4 through gas supply pipe 5.

[0046] The control unit 10 adjusts the regulator 6 based on the flow rate of gas G measured by the flow meter 7 and the gas pressure of gas G measured by the pressure gauge 8, so as to control the flow rate and pressure of gas G.

[0047] [Bubble Generation Section]

[0048] like Figure 1B As shown, the bubble generating unit 1 includes a first porous body 11 and a second porous body 12. Both the first porous body 11 and the second porous body 12 are plate-shaped components.

[0049] [First Porous Body]

[0050] The first porous body 11 has a first surface S1 and a second surface S2 facing in the opposite direction to the first surface S1. The first surface S1 is configured to contact a first region Ar1 filled with gas within the first container 2. The second surface S2 is configured to contact a second region Ar2 filled with liquid L. The areas of the first surface S1 and the second surface S2 of the first porous body 11 can be arbitrary. For example, they can be 1.0 cm × 1.0 cm, but are not limited thereto.

[0051] An arrangement of first through holes 11a is formed in the first porous body 11, penetrating between the first surface S1 and the second surface S2. In this embodiment, each first through hole 11a functions as a nozzle for generating bubbles to discharge microbubbles B. In the first through hole 11a, the end of the first surface S1 is a gas inlet for introducing gas G, and the end of the second surface S2 is a bubble outlet for discharging microbubbles B. Figure 2 As shown, the first porous body 11 causes microbubbles B to be generated at the end of the second surface S2 that is in contact with the liquid L injected from the gas inlet end of the first through hole 11a.

[0052] The first through-hole 11a connects the gas inlet and the bubble outlet in a straight line. The shape of the first through-hole 11a is a straight cylinder, such as a straight cylindrical or straight prism. However, the shape of the first through-hole 11a can be an oblique cylinder, a curved shape, or a shape in which the size of the cross section orthogonal to the through-direction varies along the through-direction.

[0053] like Figure 2 As shown, in the first porous body 11, the cross-sections of the first through holes 11a through which gas G is introduced from the same first container 2 are orthogonal to their penetration direction and have uniform shape and size (diameter D), and are arranged at a constant spacing P1. Therefore, the size of the microbubbles B generated through the multiple first through holes 11a becomes uniform (see reference). Figure 5 ).

[0054] The pore diameter D of the first through-hole 11a can be, for example, 2 μm, but can be varied depending on the size of the formed microbubble B, for example, it can be 10 μm or less. Furthermore, the arrangement spacing P1 of the first through-holes 11a can be 1250 μm. Additionally, the number of first through-holes 11a can be approximately 36. However, the pore diameter, spacing, and number of the first through-holes 11a are not limited to these.

[0055] As the first porous body 11, a silicon substrate that has undergone a hydrophilic treatment of its surface without coating with a surfactant can be used, for example. In this hydrophilic treatment, the hydrophobicity of its surface is reduced, for example, through surface processing. As the first porous body 11, the material is not limited to silicon, and materials with high rigidity and resistance to deformation, such as metals or ceramics, can be selected. However, if the first porous body 11 is used as a silicon substrate, semiconductor manufacturing technology can be used to form tiny first through-holes 11a of the desired size with high precision in the desired location.

[0056] [Second porous body]

[0057] like Figure 1B As shown, the second porous body 12 is disposed in the liquid L within the second region Ar2. The second porous body 12 has a third surface S3 and a fourth surface S4 facing in the opposite direction to the third surface S3, and is configured such that the third surface S3 is opposite to the second surface S2 of the first porous body 11. Figure 2 As shown, the second porous body 12 is positioned in the direction of growth of the microbubbles B generated at the end of the second surface S2 of the first through hole 11a. The second porous body 12 has second through holes 12a arranged between the third surface S3 and the fourth surface S4.

[0058] The second through-hole 12a is sized to allow passage of microbubbles B and liquid L. Figure 2 In the diagram, the shortest interval between the opposing inner walls in the second through hole 12a is denoted as L2. The second through holes 12a are arranged at a constant spacing P2. In the horizontal direction, the position of the second through hole 12a can also coincide with the position of the first through hole 11a, but considering the point where the microbubble B detaches, it is preferable that the first through hole 11a and the second through hole 12a are substantially staggered.

[0059] In the second porous body 12, for example, the equivalent circular diameter L2 of the second through hole 12a can be 0.18 mm, but it can be adjusted appropriately. The equivalent circular diameter L2 of the second through hole 12a can be greater than 0.1 mm. The arrangement spacing P2 of the second through holes 12a can be, for example, 254 μm. However, the equivalent circular diameter L2 of the second through hole 12a and the arrangement spacing P2 can be changed appropriately.

[0060] like Figure 3 As shown, the second porous body 12 can be a mesh structure 21 in which second through-holes 12a are formed by a mesh of mesh fibers 20. As the mesh fibers 20, materials such as stainless steel fibers that have undergone a hydrophilic treatment to improve their surface wettability without the use of surfactants can be used. However, the material of the mesh fibers 20 is not limited to this. Furthermore, the mesh fiber 20 can be a single layer. This is because if there are multiple layers, the flow resistance of the liquid L flowing through the second through-hole 12a along the thickness direction of the plate increases.

[0061] like Figure 2 As shown, the second porous body 12 is configured such that the direction of the second through hole 12a is the same as that of the first through hole 11a, and a gap E (spaced L1) is left relative to the first porous body 11 to allow the passage of microbubbles B and liquid L. The gap E can be, for example, 100 μm, but is generally preferably 0.1 mm or more, or 0.4 mm.

[0062] To form the gap E, as follows Figure 1B As shown, a spacer 13 is provided between the first porous body 11 and the second porous body 12. The spacer 13 may also have an adjustable length. In this case, the spacer 13 functions as an adjustment part that can adjust the size of the gap E. The adjustment part adjusts the gap E to obtain the size of the microbubbles B of the desired size.

[0063] Furthermore, when the second porous body 12 is configured as a mesh structure 21, the mesh structure 21 can float by the buoyancy of the generated microbubbles B, thus forming a gap E between the first porous body 11 and the mesh structure 21. In this case, the outer edges of the first porous body 11 and the second porous body 12 can be connected to each other without the spacer 13.

[0064] [Bubble growth and detachment]

[0065] like Figure 4A As shown, microbubbles B are generated at the end of the first through-hole 11a on the second surface S2 of the first porous body 11. The microbubbles B gradually grow and increase in size. In this case, a gap E is provided between the first porous body 11 and the second porous body 12, so the liquid L present in the gap E can move horizontally according to the growth of the microbubbles B. This promotes the growth of the microbubbles B.

[0066] Because a gap E is provided between the first porous body 11 and the second porous body 12, the liquid L can move freely in the horizontal direction through the gap E and pass between them. Therefore, microbubbles B can also easily grow in the horizontal direction.

[0067] If microbubble B continues to grow, then as Figure 4B As shown, the growth of microbubble B is hindered by the second porous body 12, causing it to deform in the direction of entering the second through-hole 12a. Due to this deformation, a portion of the liquid L within the second through-hole 12a seeps into the slit E. This further promotes the growth of microbubble B from the end of the first through-hole 11a.

[0068] If the second through-hole 12a grows further, then as Figure 4CAs shown, the microbubble B detaches from the first through hole 11a and passes through the second through hole 12a as an independent microbubble B and rises.

[0069] Thus, in the bubble generating section 1, a gap E is provided between the first porous body 11 and the second porous body 12, and a second through hole 12a is provided in the second porous body 12. Therefore, as the microbubbles B grow, the liquid L can easily pass through the gap E and the second through hole 12a. As a result, the microbubbles B can easily grow and easily detach from the end of the first through hole 11a. If the microbubbles B detach from the end of the first through hole 11a, a new microbubble B is generated at that end. In this way, microbubbles B are continuously generated in the bubble generating section 1.

[0070] As described above, the second porous body 12 is configured to prevent the growth of microbubbles B generated at the end of the first through hole 11a from deforming them and to promote the detachment of microbubbles from the other end of the first through hole.

[0071] like Figure 5 As shown, the generation, growth, and detachment of microbubbles B are simultaneously and intermittently repeated from multiple first through-holes 11a of the first porous body 11, resulting in the generation of many uniformly sized microbubbles B in the liquid L. This enables the monodispersity of microbubbles B.

[0072] In this embodiment, such as Figure 2 , Figures 4A to 4C as well as Figure 5 As shown, the cross-sectional shape of the mesh fiber 20, orthogonal to its long side direction, is circular. In other words, in this embodiment, as... Figure 4A As shown, the inner wall of the second through-hole 12a is bent when cut with a cross-section including the centerline CL of the second through-hole 12a extending in the through direction. This reduces the flow resistance of the inner wall of the second through-hole 12a to the liquid L, thus facilitating the movement of the liquid L and promoting the growth and detachment of microbubbles B.

[0073] like Figure 6 As shown, the cross-sectional shape of the second through-hole 12a viewed along the through direction is quadrilateral. Typically, microbubbles B tend to be spherical due to their surface tension. Therefore, with the cross-sectional shape of the second through-hole 12a being quadrilateral, passageways for liquid L can be formed at the four corners of the second through-hole 12a. Thus, liquid L easily moves along these passageways in the direction opposite to that of microbubbles B, thereby promoting the growth and detachment of microbubbles B.

[0074] Furthermore, the cross-sectional shape of the second through hole 12a viewed along the through direction is not limited to a quadrilateral; it can be a triangle or even a pentagon or other shapes. That is, the cross-sectional shape of the second through hole 12a viewed along the through direction can be a polygon.

[0075] Furthermore, assuming as Figure 7 As shown, when the spacing P1 of the first through-holes 11a is the same as the spacing P2 of the second through-holes 12a, the microbubbles B generated by two adjacent first through-holes 11a will aggregate into one second through-hole 12a, resulting in a larger microbubble B. To prevent this, in this embodiment, as... Figure 2 As shown, the spacing P1 of the first through holes 11a is twice the spacing P2 of the second through holes 12a. Thus, any microbubbles B that escape through the second through hole 12a can necessarily be microbubbles generated in any one of the first through holes 11a, thereby improving the uniformity of the microbubbles B. Basically, the spacing of the first through holes 11a only needs to be more than twice the spacing of the second through holes 12a.

[0076] In addition, such as Figure 8 As shown, the cross-section of the mesh fiber 20 orthogonal to its long side can also be rectangular. In this case, the penetration direction of the second through-hole 12a is along one diagonal of the rectangular cross-section. Thus, the inner wall of the second through-hole 12a is bent when cut with a cross-section containing the centerline CL extending along its penetration direction. Therefore, the flow resistance to the inner wall of the second through-hole 12a for the liquid L can be reduced, making the liquid L easier to move and promoting the detachment of microbubbles B.

[0077] Next, a bubble forming method using the bubble forming apparatus 100 according to this embodiment will be described. First, as Figure 9 As shown, a first porous body 11 and a second porous body are manufactured (step S1). Specifically, a silicon substrate is etched or otherwise processed to form a plurality of first through holes 11a, thereby manufacturing the first porous body 11.

[0078] Next, the bubble generating unit 1 is assembled (step S2). Specifically, the bubble generating unit 1 is assembled by attaching the mesh structure 21, i.e. the second porous body 12, to the first porous body 11 via the spacer 13.

[0079] Next, the bubble forming apparatus 100 is set up (step S3). The first container 2, the second container 3 and the bubble generating unit 1 are assembled as shown in FIG1. ​​The gas supply source 4, the gas supply pipe 5, the regulator 6, the pressure gauge 8, the flow meter 7 and the control unit 10 are installed on the assembly to assemble the bubble forming apparatus 100 as a whole.

[0080] Next, bubbles are formed in the bubble forming apparatus 100 (step S4). Specifically, gas is supplied to the first region Ar1 of the first container 2, and liquid L is supplied to the second region Ar2 of the second container 3. The control unit 10 adjusts the gas pressure in the first region Ar1 to be higher than the water pressure of the liquid L in the second region Ar2, so that the gas passes through the first through hole 11a.

[0081] In step S4, the following actions (A) and (B) are performed in the bubble generating unit 1.

[0082] (A) Gas is passed through the first through hole 11a arranged on the first porous body 11 from the end of the first surface S1 of the first through hole 11a, and tiny bubbles B are generated at the end of the second surface S2 of the first through hole 11a in contact with the liquid L.

[0083] (B) The second porous body 12, which has formed microbubbles B and second through holes 12a through which liquid L can pass, is configured in the liquid L such that the direction of the second through holes 12a is the same as that of the first through holes 11a, and a gap E is left between the second porous body 11 and the first porous body 11 so that the microbubbles B growing from the end of the second surface S2 of the first through hole 11a can be deformed.

[0084] Thus, the bubble forming apparatus 100 according to this embodiment can generate a large quantity of microbubbles B with uniform desired size without using mechanical power. Smaller microbubbles B have slower buoyancy and less inertial force. In addition, if the microbubbles B are of different sizes, smaller bubbles will be absorbed by larger bubbles, but the microbubbles B formed by this bubble forming apparatus 100 are of uniform size, so they can maintain a balance without absorbing each other. When the average bubble diameter is 200 μm or less and a bubble group of monodisperse microbubbles B is formed, even if the microbubbles B are generated at a high density, they can float without merging and dissolve and shrink in the liquid L.

[0085] [Evaluation Experiment]

[0086] The results of the evaluation test of the bubble forming apparatus 100 according to this embodiment will be explained.

[0087] The Sotte diameter (specific surface area) of the microbubbles B generated when the mesh diameter of the second through hole 12a, i.e., the mesh structure 21, was set to 2.4 mm, 0.74 mm, 0.36 mm, and 0.18 mm was measured. Figure 10 The measurement result is shown. For example... Figure 10As shown, the smaller the mesh diameter, the smaller the Sotte diameter of microbubbles B, and the smaller the variation in their Sotte diameters. In particular, when the mesh diameter (equivalent circle diameter) is set to 0.36 mm and 0.18 mm, the size of microbubbles B is homogenized. The average Sotte diameter of microbubbles B with a mesh diameter of 0.18 mm is approximately 198 μm, with a coefficient of variation (CV) of 18.4%.

[0088] exist Figure 10 In the comparison, the Sauter diameters of microbubbles B in other bubble generating devices that generate a steady-state flow field in liquid L using a first porous body 11 and generate microbubbles B through this flow field are shown, as well as the Sauter diameters of microbubbles B in other bubble generating devices that generate microbubbles B by vibrating the first porous body 11. Figure 10 As shown, in the bubble forming apparatus 100 according to this embodiment, when microbubbles B are generated with mesh diameters set to 0.36 mm and 0.18 mm, the difference in Soder diameter of microbubbles B is reduced compared to the cases where microbubbles B of the same diameter are generated through steady-state flow fields and vibrating flow fields. This evaluation experiment clearly demonstrates that the bubble forming apparatus 100 according to this embodiment achieves miniaturization and monodispersion of microbubbles B.

[0089] Furthermore, the mass transport capacity coefficient K of the microbubbles B in the liquid L is evaluated when microbubbles B are formed using the bubble forming apparatus 100 according to this embodiment. L a. Mass transport capacity coefficient K L 'a' represents the number of tiny air bubbles 'B' that can dissolve in the same volume.

[0090] Figure 11 The mass transport capacity coefficient K is shown. L a) Characteristics relative to the gas column velocity. In this graph, in addition to the bubble forming apparatus 100 according to this embodiment, the mass transport capacity coefficient K, which varies with the gas column velocity [cm / s], is also plotted for a stacked slit type bubble forming apparatus that generates bubbles through stacked slits, a sintered ball type bubble forming apparatus that generates bubbles through sintered balls, and a single-hole nozzle type bubble forming apparatus that generates bubbles through a single-hole nozzle. L The change of 'a'.

[0091] like Figure 11 As shown, in the bubble forming apparatus 100 according to this embodiment, the mass transport capacity coefficient K La is significantly increased by 85 times compared to when there is no second porous body 12. This indicates that the bubble forming apparatus 100 has a high gas dissolution capacity at low gas flow rates. Conversely, this also means that the bubble forming apparatus 100 according to this embodiment can be miniaturized and made portable.

[0092] Figure 12 The mass transport capacity coefficient K is shown. L a. Characteristics relative to the required power. Figure 12 The material transport capacity coefficient K is shown in the case where a second porous body 12 without mesh (second through-hole) is used in the bubble forming apparatus 100 according to this embodiment, and in the cases where the mesh aperture is set to 0.74 mm, 0.36 mm, and 0.18 mm. L a. For example Figure 12 As shown, Venturi, pressurized dissolution, swirling, and jet-type bubble forming devices require power to drive liquid flow, thus demanding significant power. Furthermore, even devices using orifice plates or constant-flow nozzles require increased mass transfer capacity coefficient K. L a) would also require increased power. In contrast, in the bubble forming apparatus 100 of this embodiment, it is clearly demonstrated that a high gas dissolution capacity can be obtained with minimal power supplied at a specified gas pressure. Furthermore, in the bubble forming apparatus 100 of this embodiment, it is also clearly demonstrated that the smaller the mesh diameter, the greater the mass transport capacity coefficient K can be. L a.

[0093] As detailed above, in the bubble forming apparatus 100 according to this embodiment, a gap E is formed between the first porous body 11 and the second porous body 12 so that the liquid L in the peripheral region of the microbubbles B can pass freely, so that the liquid flow can be driven by a power source to generate a large number of uniformly sized microbubbles.

[0094] According to the bubble forming apparatus 100 of this embodiment, the shape and size (diameter D) of the cross-section of the first through-hole 11a orthogonal to the through direction are uniform, and they are arranged at the same spacing P1. In this way, a large number of uniformly sized microbubbles B can be formed at one time. However, there may be differences in the cross-section of the first through-hole 11a in the first porous body 11, or there may be differences in the spacing of the first through-hole 11a.

[0095] According to the bubble forming apparatus 100 of this embodiment, the arrangement spacing P1 of the first through holes 11a is more than twice the arrangement spacing P2 of the second through holes 12a. However, it is not limited to this. The first through holes 11a and the second through holes 12a can be configured such that the microbubbles B generated by each of the plurality of first through holes 11a do not aggregate into a single second through hole 12a.

[0096] According to the bubble forming apparatus 100 of this embodiment, the second porous body is formed by mesh fibers 20 to create a mesh structure 21 constituting the mesh of the second through-hole 12a. The mesh structure 21 is adapted to hinder the growth of microbubbles B generated in the first through-hole 11a, thereby obtaining microbubbles B of the desired size. Furthermore, if the second porous body 12 is used as the mesh structure 21, as described above, the buoyancy of the microbubbles B generated in the first through-hole 11a can also be used to make the mesh structure 21 float, forming a gap E between it and the first porous body 11.

[0097] According to the bubble forming apparatus 100 of this embodiment, when the second through hole 12a is cut with a cross-section including the centerline CL extending in its through direction, the inner wall of the second through hole 12a is bent or curved. This reduces the flow resistance of the liquid L through the second through hole 12a, allowing the microbubbles B and the liquid L to pass easily through the second through hole 12a. Therefore, the microbubbles B can be easily detached.

[0098] According to the bubble forming apparatus 100 of this embodiment, the cross-sectional shape of the second through hole 12a viewed along the through direction is polygonal. This ensures a flow path for the liquid L within the second through hole 12a. Therefore, it is easy for the microbubbles B to detach.

[0099] According to the bubble forming apparatus 100 of this embodiment, the spacer 13 functions as an adjustment part capable of adjusting the size of the gap E. By changing the size of the gap E, the size of the formed microbubbles B can be changed.

[0100] Furthermore, by adjusting the shape, size, and number of pores in the cross-sections of the first through-hole 11a and the second through-hole 12a, the cross-sectional shape of the mesh fiber, the ratio of the arrangement spacing between the first through-hole 11a and the second through-hole 12a, and the affinity of the first porous body 11 and the second porous body 12 for the liquid L (e.g., water), the size of the detached microbubbles B can be adjusted.

[0101] Furthermore, in the bubble forming apparatus 100 according to this embodiment, the second porous body 12 is used as a mesh structure 21. However, it is not limited to this. For example, the second porous body 12 may also be formed from a substrate similar to the first porous body 11.

[0102] Furthermore, in this embodiment, the bubble generating unit 1 is configured such that the second surface S2 and the fourth surface S4 face upwards. However, it is not limited to this. For example, the bubble generating unit 1 may also be configured such that the second surface S2 and the fourth surface S4 face horizontally.

[0103] Furthermore, the bubble forming apparatus 100 according to this embodiment can be a completely closed batch processing apparatus. Therefore, the material of the bubble forming apparatus 100 can be selected based on the experimental environment, and it can be a material with excellent pressure resistance and chemical resistance. In addition, the type of gas G supplied can be freely set.

[0104] The bubble forming apparatus 100 described in this embodiment not only possesses the ability to miniaturize bubbles and the ability to control the size of microbubbles B with high precision, but also enables the miniaturization and portability of the device, allowing it to be installed in bottles, small water tanks, etc. Therefore, in addition to its applications in primary industries such as aquariums and bioactive products, it can be widely used in fields such as beauty and skincare, beverages, and adding textures and flavors, such as life sciences and pharmaceuticals, where small-batch, multi-variety production is required. It can also be used for household toilet cleaning, etc.

[0105] Furthermore, the bubble-forming apparatus 100 of this embodiment has a device structure that generates microbubble groups in the main liquid without applying external force, simply by providing a second porous body (baffle) 12 with a mesh structure on the first porous body (porous plate) 11. Therefore, by replacing the porous plate, which is most commonly used as a bubble-generating device in the conventional chemical industry, with the bubble-generating section 1 of this embodiment, a leap in bubble-generating capacity can be achieved, thus the bubble-generating section 1 has significant meaning and value.

[0106] This invention can be implemented and modified in various ways without departing from its broad spirit and scope. Furthermore, the above-described embodiments are for illustrative purposes only and do not limit the scope of the invention. That is, the scope of the invention is defined not by the embodiments, but by the claims. Moreover, various modifications implemented within the scope of the claims and their equivalents are considered to be within the scope of the invention.

[0107] Furthermore, this application claims priority based on Japanese Patent Application No. 2023-169190, filed on September 29, 2023, and incorporates the entire description, claims, and drawings of Japanese Patent Application No. 2023-169190 into this specification by reference.

[0108] Industrial applications

[0109] This invention can be applied to the formation of microbubbles.

[0110] Explanation of reference numerals in the attached figures

[0111] 1 Bubble generating unit, 2 First container, 3 Second container, 4 Gas supply source, 5 Gas supply pipe, 6 Regulator, 7 Flow meter, 8 Pressure gauge, 10 Control unit, 11 First porous body, 11a First through hole, 12 Second porous body, 12a Second through hole, 13 Spacer, 20 Mesh fiber, 21 Mesh structure, 100 Bubble forming device, Ar1 First region, Ar2 Second region, B Microbubble, CL Centerline, E Gap, G Gas, L Liquid, S1 First surface, S2 Second surface, S3 Third surface, S4 Fourth surface.

Claims

1. A bubble forming apparatus comprising: a first porous body having an array of first through-holes into which gas is injected from one end to generate minute bubbles at the other end in contact with a liquid; a second porous body having an array of second through-holes through which the minute bubbles and the liquid can pass, and being disposed in the liquid to deform the minute bubbles growing from the other end of the first through-holes, the second porous body being disposed between the first porous body with the second through-holes in the same direction as the first through-holes with a gap through which the minute bubbles and the liquid can pass.

2. The bubble forming apparatus according to claim 1, wherein in the array of the first through-holes, the shape and size of a cross section of each of the first through-holes orthogonal to the direction of the through-holes are uniform and the array is arranged at a constant pitch.

3. The bubble forming apparatus according to claim 1, wherein the first through-holes and the second through-holes are arranged at a constant pitch, and the pitch of the array of the first through-holes is twice or more the pitch of the array of the second through-holes.

4. The bubble forming apparatus according to claim 1, wherein the second porous body is a mesh structure having the second through-holes formed by meshes of a meshed fiber.

5. The bubble forming apparatus according to claim 1, wherein the shape of an inner wall of the second through-holes when cut by a cross section including a center line of the second through-holes extending in the direction of the through-holes is in a bent or curved state.

6. The bubble forming apparatus according to claim 1, wherein the cross-sectional shape of the second through-holes as viewed in the direction of the through-holes is a polygonal shape.

7. The bubble forming apparatus according to claim 1, comprising an adjusting portion capable of adjusting the size of the gap.

8. A bubble forming method comprising: passing gas through first through-holes of a first porous body from one end of the first through-holes to generate minute bubbles at the other end of the first through-holes in contact with a liquid; and disposing a second porous body having an array of second through-holes through which the minute bubbles and the liquid can pass in the liquid with the second through-holes in the same direction as the first through-holes and between the first porous body with a gap through which the minute bubbles and the liquid can pass to deform the minute bubbles growing from the other end of the first through-holes. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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