Air bubble generator

Abstract

To generate a liquid containing air bubbles sufficiently.SOLUTION: An air bubble generator 1 includes: a casing 2 where a fluid mixture of a liquid and a gas supplied to the inside flows in an axial direction X from an inlet (a liquid inlet 211 and a gas inlet 212) toward an outlet (a fluid outlet 2113); a first member 5 supported by the casing in the casing; and a second member 6 which is supported by a shaft 3 extending in the axial direction and rotates around the shaft relative to the first member in the casing and which has blades 612 extending from the shaft in a radial direction and overlapping with the first member in the axial direction and the radial direction.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed herein relates to an air bubble generating device. [Background technology]

[0002] Liquids containing fine bubbles are used in various facilities, including wastewater treatment facilities. Various types of devices are known as devices for generating fine bubbles. For example, Patent Document 1 describes a conventional fine bubble generator that releases sucked gas into liquid while crushing it into fine particles. Specifically, this conventional fine bubble generator includes a disk immersed in liquid and a hollow rotating shaft pipe attached to the center of the disk. A plurality of hollow pipes are attached to the disk in a radial arrangement. When the disk rotates, liquid flows into each hollow pipe by centrifugal force, and gas is sucked into the hollow pipe from the hollow rotating shaft pipe by negative pressure when the liquid passes through the hollow pipe. The sucked gas is crushed into fine particles in each hollow pipe and released into the liquid from the outer periphery of the disk.

[0003] Patent Document 2 describes a conventional ultra-fine bubble generating device that does not mix aspirated gas with the liquid, but generates fine bubbles from air dissolved in the liquid. Specifically, this conventional generating device includes a cylindrical member having a plurality of triangular prism-shaped protrusions. The cylindrical member rotates around its axis in the liquid. As the cylindrical member rotates, turbulence is generated by the protrusions, and the air contained in the liquid breaks down into extremely fine particles, generating ultra-fine bubbles. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-34292 A [Patent Document 2] JP 2017-80721 A Summary of the Invention [Problem to be solved by the invention]

[0005] The microbubble generator described in Patent Document 1 utilizes the negative pressure generated by the rotation of a disk. Even if the rotation speed of the disk is increased, there is a limit to the amount of air that can be sucked in. It is difficult for the microbubble generator described in Patent Document 1 to generate liquid that contains a sufficient amount of microbubbles.

[0006] The ultra-fine bubble generating device described in Patent Document 2 generates fine bubbles from air dissolved in liquid. For liquids with a small amount of dissolved air, such as wastewater, this generating device cannot generate a sufficient amount of fine bubbles. In addition, since this conventional generating device only rotates a cylindrical member immersed in the liquid, there is a risk that a sufficient amount of fine bubbles will not be generated because a swirling flow will be generated around the cylindrical member.

[0007] The techniques disclosed herein produce liquids that are fully laden with air bubbles. [Means for solving the problem]

[0008] The technology disclosed herein relates to an air bubble generating device. a casing into which a mixed fluid of liquid and gas flows in an axial direction from an inlet to an outlet; a first member supported by the casing inside the casing; a second member supported by a shaft extending in the axial direction within the casing and rotating around the shaft relative to the first member, the second member having a blade extending from the shaft in a radial direction perpendicular to the axial direction and overlapping with the first member in the axial direction and the radial direction; It is equipped with:

[0009] In this air bubble generation device, a liquid and a gas are supplied to the inside of a casing. The liquid and the gas may be supplied to the inside of the casing separately, or a mixed fluid in which the liquid and the gas are mixed in advance may be supplied to the inside of the casing. Inside the casing, the mixed fluid flows in the axial direction from the inlet to the outlet.

[0010] The air bubble generating device includes a first member. The first member is supported by the casing.

[0011] The air bubble generating device comprises a second member. The second member is supported inside the casing on an axially extending shaft. The second member rotates around the shaft relative to the first member. The relative rotation between the first member and the second member may be realized as follows: (1) the casing and the first member may be stationary and the shaft and the second member may rotate, (2) the casing and the first member may rotate and the shaft and the second member may be stationary, or (3) the casing and the first member may rotate and the shaft and the second member may rotate, for example, in opposite directions or in the same direction but at different rotational speeds.

[0012] The second member has a blade. The blade overlaps with the first member in the axial and radial directions. With the relative rotation of the second member, the mixed fluid is stirred between the blade and the first member, and bubbles are generated. Here, the bubbles generated by this bubble generating device may be fine bubbles including microbubbles having an average diameter of less than 100 μm and 1 μm or more, and ultrafine bubbles having an average diameter of less than 1 μm. The bubbles generated by this bubble generating device may be larger than fine bubbles, that is, bubbles having an average diameter of 100 μm or more.

[0013] The relatively rotating blades also shear the mixed fluid in which the bubbles are generated between the first member and the second member in the circumferential and radial directions perpendicular to the axial and radial directions. The generated bubbles become finer. The combination of the relatively rotating first and second members can generate a sufficient amount of fine bubbles. The bubble generating device can generate a liquid containing a sufficient amount of bubbles compared to conventional devices.

[0014] The first member has a plurality of projections that project in the radial direction from an inner surface of the casing and are spaced apart in the axial direction, The second member may be located between the projections.

[0015] This structure increases the number of shear points between the first and second members, which is advantageous in increasing the amount of bubbles generated. In addition, the multiple protrusions of the first member aligned in the axial direction and the second member between the protrusions impede the mixed fluid from flowing in the axial direction, increasing the shear frequency of the mixed fluid as it flows from the inlet to the outlet. The increased shear frequency is also advantageous in generating fine bubbles, and increases the amount of bubbles generated.

[0016] The first member may have a second projection that is located between the projections in the axial direction, protrudes in the radial direction from an inner surface of the casing, and faces the second member.

[0017] The gas inside the casing tends to be sent radially outward due to centrifugal force generated by the relative rotation of the second member. The second protrusion, which faces the second member in the radial direction, interferes with the gas and restricts the gas from flowing in the axial direction. The second protrusion causes the gas to remain on the radial outer periphery inside the casing. The retained gas bubbles become fine bubbles as the second member rotates relative to the gas. The second protrusion contributes to increasing the amount of bubbles generated by the bubble generation device.

[0018] The second projection may be continuous in the circumferential direction.

[0019] The secondary projections that are continuous in the circumferential direction effectively restrict the gas from flowing in the axial direction, resulting in the generation of a greater number of fine bubbles.

[0020] The protrusions may be arranged in a plurality of positions at intervals in the circumferential direction.

[0021] As the second member rotates relative to the shaft, a swirling flow is generated inside the casing, centered on the shaft. The multiple protrusions arranged at intervals in the circumferential direction interfere with the swirling flow, increasing the frequency of shearing of the mixed fluid, further increasing the amount of bubbles generated.

[0022] The first member is A rod-shaped member extending in the axial direction; The housing may include an annular member that extends circumferentially along the inner surface of the casing and that engages with the rod-shaped member to position the rod-shaped member against the inner surface of the casing.

[0023] The combination of a rod-shaped member and an annular member is advantageous in realizing the first member that is supported by the casing.

[0024] The second member may include a plurality of blades radiating from the shaft in the radial direction.

[0025] The multiple blades that rotate relative to one another shear the mixed fluid between themselves and the first member, causing the bubbles to become finer and increasing the amount of bubbles generated. Effect of the Invention

[0026] As described above, the air bubble generating device can generate liquid containing a sufficient amount of air bubbles. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a perspective view of the air bubble generating device. [Diagram 2] FIG. 2 is an exploded view of the air bubble generating device. [Diagram 3] FIG. 3 is a front view (left) and a side view (right) of the first member. [Figure 4] FIG. 4 is a front view and an AA cross-sectional view of the rod-shaped member, and a front view and a side view of the annular member and the impeller. [Diagram 5] FIG. 5 is a cross-sectional view (left) and a B-B cross-sectional view (right) of the inside of the casing. [Figure 6] FIG. 6 is a cross-sectional view (left) and a CC cross-sectional view (right) of the inside of a casing according to a modified example. [Figure 7] FIG. 7 is a cross-sectional view (left) and a DD cross-sectional view (right) of the inside of a casing according to a modified example. [Figure 8] FIG. 8 is a front view of a rod-shaped member according to a modified example, and a side view and an E-E sectional view of an annular member. [Figure 9] FIG. 9 is a cross-sectional view (left) and an FF cross-sectional view (right) of the inside of a casing according to a modified example. [Figure 10] FIG. 10 is a side view of a second member according to a modified example. [Figure 11] FIG. 11 is a cross-sectional view (left) and a cross-sectional view along line GG (right) of the inside of a casing according to a modified example. [Figure 12] FIG. 12 is a perspective view of a bubble generation device according to a modified example. [Figure 13] FIG. 13 is a perspective view of an air bubble generation device according to still another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the air bubble generating device will be described with reference to the drawings. The air bubble generating device described here is an example.

[0029] (Overall structure of the air bubble generating device) FIG. 1 shows the entirety of an air bubble generating device 1. The air bubble generating device 1 generates air bubbles in a liquid. The air bubble generating device 1 is used for wastewater treatment in a wastewater treatment facility. Specifically, the air bubble generating device 1 generates fine air bubbles in the liquid to be treated. When the fine air bubbles are generated, the dissolved oxygen concentration in the liquid increases. Furthermore, when the liquid to be treated contains solid matter, the fine air bubbles in the liquid adhere to the solid matter, making it possible to float the solid matter and collect it.

[0030] Here, the bubbles generated by the air bubble generating device 1 may be fine bubbles including microbubbles having an average diameter of less than 100 μm and 1 μm or more, and ultrafine bubbles having an average diameter of less than 1 μm. The bubbles generated by the air bubble generating device 1 may also be larger than fine bubbles, that is, bubbles having an average diameter of 100 μm or more.

[0031] 2 is an exploded perspective view of the air bubble generation device 1. The air bubble generation device 1 includes a casing 2. The casing 2 houses a first member 5 and a second member 6, which will be described later. In the air bubble generation device 1, the first member 5 and the second member 6 rotate relatively inside the casing 2, thereby agitating a mixed fluid of liquid and gas and mechanically breaking down the generated air bubbles into fine particles.

[0032] The casing 2 has a tube 21. The tube 21 is a cylinder extending along the axis of the air bubble generation device 1. A first end and a second end opposite to the first end of the tube 21 are each open. The first end is the end on the right side of the paper in Fig. 2, and the second end is the end on the left side of the paper in Fig. 2. The tube 21 may have a half-split structure in which two members separated along the center line are joined together.

[0033] In the following description, the direction in which the axis of the tube 21 extends is referred to as the axial direction X, and the direction from the front right to the back left of the paper in Figures 1 and 2 is the positive direction of the axial direction X. The positive direction of the axial direction X corresponds to the mainstream direction of the fluid in the bubble generation device 1, as will be described later.

[0034] The cylinder 21 has a liquid inlet 211. The liquid inlet 211 is located on the outer circumferential surface of the first end of the cylinder 21. The liquid inlet 211 is a tube that communicates with the inside of the cylinder 21 and protrudes outward in the radial direction r from the outer circumferential surface of the first end of the cylinder 21. Here, the radial direction r is a direction perpendicular to the axial direction X, and the direction toward the outside from the axis of the cylinder 21 is defined as the positive direction of the radial direction r. For example, a pump is connected to the liquid inlet 211. The pump forcibly flows a liquid, for example, water, into the inside of the casing 2 through the liquid inlet 211.

[0035] The cylinder 21 also has a gas inlet 212. The gas inlet 212 is located on the outer circumferential surface of the first end of the cylinder 21, aligned with the liquid inlet 211 in the circumferential direction θ. Here, the circumferential direction θ is a direction perpendicular to each of the axial direction X and the radial direction r, and the rotation direction of the prime mover 4 described later is defined as the positive direction of the circumferential direction θ. The gas inlet 212 is a tube communicating with the inside of the cylinder 21, and protrudes outward in the radial direction r from the outer circumferential surface of the first end of the cylinder 21. For example, a blower is connected to the gas inlet 212. The blower forcibly flows gas, for example, air, into the inside of the casing 2 through the gas inlet 212.

[0036] The tube 21 further has a fluid outlet 213. The fluid outlet 213 is located on the outer circumferential surface of the second end of the tube 21. The fluid outlet 213 is a tube that communicates with the inside of the tube 21 and protrudes outward in the radial direction r from the outer circumferential surface of the second end of the tube 21. The fluid outlet 213 opens downward in a portion below the center of the tube 21. The fluid outlet 213 causes the liquid containing the fine bubbles to flow out from the inside of the casing 2 to the outside. A pipe is connected to the fluid outlet 213. Inside the casing 2, the mixed fluid mainly flows in the axial direction X from the first end to the second end of the tube 21.

[0037] Here, since the fluid outlet 213 opens downward in the lower part of the cylinder 21, the liquid containing micro-bubbles can flow out through the fluid outlet 213 even if the inside of the cylinder 21 is not filled with the liquid containing micro-bubbles. This structure can reduce the driving force of the prime mover 4, which will be described later.

[0038] The casing 2 has a first lid 22. The first lid 22 closes the opening at the first end of the cylinder 21, making the casing 2 watertight. The first lid 22 also supports a first bearing 24. The first bearing 24 rotatably supports a first end 32 of the shaft 3, which will be described later.

[0039] The casing 2 has a second lid 23. The second lid 23 is attached to the opening at the second end of the tube 21. The second lid 23 has a through hole 231 extending in the axial direction X. The second end 33 of the shaft 3 penetrates the second lid 23. The second lid 23 also supports a second bearing 25. The second bearing 25 rotatably supports the second end 33 of the shaft 3. The second lid 23 also houses a seal 26 in the through hole 231. The seal 26 seals the periphery of the second end 33 of the shaft 3, thereby making the casing 2 watertight. The seal 26 is, for example, a mechanical seal. The seal 26 is not limited to a specific structure.

[0040] The air bubble generation device 1 includes a shaft 3. The shaft 3 extends along the axial direction X. The shaft 3 is inserted into a cylinder 21 of a casing 2. The shaft 3 and the cylinder 21 are coaxial. The shaft 3 has a support portion 31, and a first end portion 32 and a second end portion 33 extending from an end of the support portion 31 along the axial direction X. The support portion 31 supports a second member 6, which will be described later. The first end portion 32 is supported by a first bearing 24. The second end portion 33 is supported by a second bearing 25. The shaft 3 is rotatably supported by the casing 2. In other words, the shaft 3 can rotate relatively to the casing 2.

[0041] The air bubble generation device 1 includes a prime mover 4. The prime mover 4 is, for example, an electric motor. However, the prime mover 4 is not limited to an electric motor. An output shaft 41 of the prime mover 4 is coupled to the second end 33 of the shaft 3 inside the second lid 23. The prime mover 4 rotates the shaft 3. However, the prime mover 4 may be coupled to the first end 32 of the shaft 3.

[0042] The air bubble generation device 1 comprises a first member 5. The first member 5 is supported by a casing 2. The air bubble generation device 1 comprises a second member 6. The second member 6 is supported by a shaft 3. When the shaft 3 rotates, the second member 6 rotates together with the shaft 3. The second member 6 rotates relative to the first member 5. The first member 5 and the second member 6 cooperate to generate air bubbles inside the casing 2. The structures of the first member 5 and the second member 6 will be described in detail later.

[0043] (Structure of the first component) FIG. 3 shows the first member 5. The outer periphery of the first member 5 in the radial direction r is circular in side view as shown in the right diagram of FIG. 3, and the first member 5 has a hole 50 extending in the axial direction X at the center of the radial direction r. The first member 5 is generally cylindrical. The first member 5 is inserted into the tube 21 of the casing 2 (see also FIG. 5). The first member 5 is supported by the tube 21. The shaft 3 is inserted into the hole 50 of the first member 5.

[0044] As described above, the first member 5 is supported by the casing 2. The first member 5 may be fixed to the casing 2. The first member 5 may not be fixed to the casing 2. If the first member 5 is not fixed to the casing 2, it becomes easy to replace the first member 5 when the first member 5 deteriorates, for example. Even if the first member 5 is not fixed to the casing 2, the first member 5 does not or does not substantially rotate relative to the casing 2 due to its own weight when the air bubble generation device 1 is in operation.

[0045] The first member 5 is configured by combining a rod-shaped member 51 and an annular member 52. Fig. 4 illustrates the rod-shaped member 51 and the annular member 52.

[0046] The rod-shaped member 51 extends in the axial direction X. The rod-shaped members 51 are lined up along the inner circumferential surface of the cylinder 21 at equal intervals in the circumferential direction θ.

[0047] The rod-shaped member 51 has a base 511 and a plurality of protrusions 512. The base 511 is a thin flat plate extending in the axial direction X. The base 511 abuts against the inner circumferential surface 214 of the tube 21 (see also FIG. 5). The plurality of protrusions 512 each protrude inward in the radial direction r from the base 511. The protrusion length L1 of the protrusion 512 is sufficiently longer than the radial length L2 of the base 511. As described below, the protrusion length L1 of the protrusion 512 is set to a length that allows the protrusion 512 and the blade 612 of the second member 6 to overlap in the radial direction r (see also FIG. 5).

[0048] The multiple protrusions 512 are aligned at equal intervals in the axial direction X. The number of protrusions 512 may be any appropriate number.

[0049] The base 511 has an engagement portion 513. The engagement portion 513 is located between the protrusions 512 adjacent to each other in the axial direction X. More precisely, the engagement portion 513 is located not at all positions between the protrusions 512 adjacent to each other, but at every other position in the axial direction X. The engagement portion 513 is a recess that recesses outward in the radial direction r from the end of the base 511. The engagement portion 513 engages with the annular member 52.

[0050] The annular member 52 has an annular shape. The annular member 52 extends in the circumferential direction along the inner circumferential surface 214 of the cylinder 21 of the casing 2. The annular member 52 has a thickness T1 in the radial direction r that is greater than the length L2 of the base 511 of the rod-shaped member 51.

[0051] The annular member 52 has grooves 523. The grooves 523 are recessed radially inward from the outer circumferential edge of the annular member 52. The grooves 523 are positioned at equal intervals in the circumferential direction θ in the annular member 52. The grooves 523 are portions that engage with the engaging portions 513 of the rod-shaped member 51 (see the two-dot chain arrow in FIG. 4). The number of grooves 523 corresponds to the number of rod-shaped members 51 that constitute the first member 5.

[0052] 2, 3 or 4, the annular member 52 is located inward in the radial direction r with respect to the rod-shaped members 51 arranged at equal intervals in the circumferential direction θ. FIG. 5 shows the first member 5 and the second member 6 housed inside the casing 2. The groove 523 of the annular member 52 engages with the engaging portion 513 of the rod-shaped member 51, whereby the rod-shaped member 51 is sandwiched between the inner circumferential surface 214 of the tube 21 of the casing 2 and the annular member 52. The annular member 52 engages with each of the multiple engaging portions 513 arranged in the axial direction X on the rod-shaped member 51. The annular members 52 are arranged at equal intervals in the axial direction X.

[0053] The protrusions 512 of the rod-shaped member 51 protrude inward in the radial direction r from the inner circumferential surface 214 of the tube 21. The protrusions 512 are arranged at equal intervals in the axial direction X as shown in the left diagram of Fig. 3, and are arranged at equal intervals in the circumferential direction θ as shown in the right diagram of Fig. 3.

[0054] The annular member 52 has a thickness T1 that is longer than the length L2 of the base 511. As shown in the right diagram of FIG. 5, the annular member 52 forms a second protrusion 521 that protrudes inward in the radial direction r from the base 511. The length (T1-L2) of the second protrusion 521 is shorter than the length (L1) of the protrusion 512. The second protrusion 521 is located between adjacent protrusions 512 in the axial direction X. As described above, the annular member 52 that engages with the engagement portion 513 of the base 511 is not located at all positions between adjacent protrusions 512, so the second protrusions 521 are located between every other adjacent protrusion in the axial direction X.

[0055] The combination of the rod-shaped member 51 and the annular member 52 is advantageous for realizing the first member 5 supported by the casing 2 and having a large number of protrusions 512 and second protrusions 521.

[0056] (Structure of the second member) Fig. 2 shows the second member 6. As shown by the two-dot chain line in the right diagram of Fig. 3, the outer periphery of the second member 6 in the radial direction r is substantially circular in side view. The second member 6 is fitted onto the shaft 3 and supported by the shaft 3. The second member 6 rotates about the axis of the air bubble generation device 1 as the shaft 3 rotates.

[0057] 2 or 5, the second member 6 has an impeller 61 and a spacer 62. The impellers 61 and the spacers 62, which are fitted onto the shaft 3, are arranged alternately in the axial direction X.

[0058] 4, the impeller 61 has a hub 611 and a plurality of blades 612. The hub 611 has a through hole that is inserted into the support portion 31 of the shaft 3. Reference numeral 613 denotes a key groove. The impeller 61 rotates together with the shaft 3.

[0059] The blades 612 protrude radially outward from the hub 611 in the radial direction r. The blades 612 are positioned at equal intervals in the circumferential direction θ. As shown in Fig. 5, the radial length L3 of the blade 612 is set to be equal to or greater than the length at which the blade 612 overlaps with the protrusion 512 of the rod-shaped member 51 of the first member 5 in the radial direction r when the second member 6 is housed inside the casing 2, and equal to or less than the length at which the blade 612 does not interfere with the annular member 52 of the first member 5, i.e., the second protrusion 521.

[0060] The spacer 62 is interposed between the impellers 61 in the axial direction X, as shown in FIG. 2 or the right diagram of FIG. 5. The spacer 62 is annular, and is fitted onto the support portion 31 of the shaft 3. The spacer 62 maintains a constant distance between the impellers 61 in the axial direction X. Inside the casing 2, the impeller 61 overlaps with the protrusion 512 of the first member 5 in the axial direction X, as shown in FIG. 5, and is located between the protrusions 512 of the first member 5. The blades 612 of the impeller 61 also face the annular member 52 in the radial direction r every other blade in the axial direction X.

[0061] As described above, the shaft 3 is provided with a plurality of impellers 61. In a state where the plurality of impellers 61 are attached to the shaft 3, the blades 612 are located at the same circumferential θ position for the plurality of impellers 61 arranged in the axial direction X (see the two-dot chain line in the right diagram of FIG. 3). That is, the blades 612 are located at overlapping positions in the axial direction X for the plurality of impellers 61. The blades 612 may be located at different positions in the circumferential direction θ for the plurality of impellers 61. That is, when the second member 6 is viewed from the first end of the second member 6 along the axial direction X, the blades 612 of the plurality of impellers 61 may be located alternately. The alternate arrangement of the blades 612 is advantageous for restricting the flow of the mixed fluid in the axial direction X and generating fine bubbles by increasing the shear frequency, as described later.

[0062] (Operation of the air bubble generator) The air bubble generation device 1 is supplied with liquid through a liquid inlet 211 and with gas through a gas inlet 212. The prime mover 4 rotates the shaft 3. Inside the casing 2, the second member 6 rotates relative to the first member 5. With the relative rotation of the second member 6, the mixed fluid inside the casing 2 is agitated, and air bubbles are generated.

[0063] The blades 612 of the second member 6, which rotate relative to each other, shear the mixed fluid in the circumferential direction θ and the radial direction r between them and the protrusions 512 of the first member 5. The generated bubbles become even finer. The combination of the first member 5 and the second member 6, which rotate relative to each other, can generate a sufficient amount of fine bubbles by shearing the mixed fluid. The air bubble generation device 1 can generate liquid that contains a sufficient amount of air bubbles compared to conventional devices. The liquid containing the fine bubbles flows out from the inside of the casing 2 to the outside through the fluid outlet 213.

[0064] The first member 5 has a plurality of protrusions 512 spaced apart in the axial direction X, and the blades 612 of the second member 6 are located between the protrusions 512. This structure increases the number of shear generating locations between the first member 5 and the second member 6, increasing the amount of bubbles generated. In addition, the plurality of protrusions 512 aligned in the axial direction X and the plurality of blades 612 aligned in the axial direction X impede the mixed fluid from flowing in the axial direction X, increasing the shear frequency of the mixed fluid. The increased shear frequency also increases the amount of bubbles generated.

[0065] The protrusions 512 of the first member 5 are arranged at intervals in the circumferential direction θ. As the second member 6 rotates relative to one another, a swirling flow is generated inside the casing 2, centered on the shaft 3. The protrusions 512 arranged at intervals in the circumferential direction θ interfere with the swirling flow, increasing the frequency of shearing of the mixed fluid. This further increases the amount of bubbles generated.

[0066] Furthermore, the blades 612 of the second member 6 are also arranged at intervals in the circumferential direction θ. Each of the blades 612 rotating relatively shears the mixed fluid between itself and the protrusion 512. The amount of bubbles generated increases.

[0067] The first member 5 further has a second protrusion 521. The second protrusion 521 is located between the protrusions 512, protrudes from the inner peripheral surface 214 of the casing 2 in the radial direction r, and faces the blade 612 of the second member 6. Due to the centrifugal force generated by the relative rotation of the second member 6, the gas inside the casing 2 tends to be sent outward in the radial direction r (see the arrow in the right diagram of FIG. 5). The second protrusion 521 facing the blade 612 in the radial direction r interferes with the gas and restricts the gas from flowing in the axial direction X. The second protrusion 521 causes the gas to remain on the outer periphery in the radial direction r inside the casing 2. The retained gas becomes fine bubbles as the second member 6 rotates relative to the gas. The second protrusion 521 contributes to an increase in the amount of bubbles generated by the bubble generation device 1.

[0068] 5, the second protrusions 521 are continuous in the circumferential direction θ. The second protrusions 521 that are continuous in the circumferential direction θ effectively restrict the gas from flowing in the axial direction X. Since the gas remains in the outer periphery in the radial direction r, more fine bubbles are generated.

[0069] The air bubble generator 1 is characterized by a larger flow path compared to conventional air bubble generators. The air bubble generator 1 with a larger flow path has the advantage of being able to treat turbid water as is, and is suitable as an air bubble generator used for wastewater treatment. In addition, adding activated carbon powder to the inside of the casing 2 improves the activated carbon effect, such as reducing the COD (Chemical Oxygen Demand) of the wastewater and decolorizing it.

[0070] The air bubble generating device 1 can also generate ozone water by generating fine ozone bubbles. The ozone water can be used, for example, to purify closed water areas. Furthermore, by utilizing the high oxidizing power of ozone water, the ozone water generated by the air bubble generating device 1 can also be used for cleaning, deodorization, or decolorization. The air bubble generating device 1 can seal the supplied gas inside the casing 2. The air bubble generating device 1 can prevent ozone from leaking into the atmosphere, ensure high safety, and dissolve expensive ozone gas in water with high efficiency.

[0071] The use of the air bubble generation device 1 is not limited to wastewater treatment. The use of the air bubble generation device 1 is various.

[0072] (Variation 1) Fig. 6 shows a modified example of the second projection. The second projections 522 of the first member 5 shown in Fig. 6 are not continuous in the circumferential direction θ, but are arranged at intervals in the circumferential direction θ.

[0073] The multiple second protrusions 522 arranged at intervals in the circumferential direction θ interfere with the swirling flow inside the casing 2. This increases the amount of air bubbles generated.

[0074] 6, in the first member 5, the second protrusion 522 and the protrusion 512 are misaligned in the circumferential direction θ. The protrusion 512 and the second protrusion 522, which are misaligned in the circumferential direction θ, obstruct the flow of the mixed fluid in the axial direction X. As described above, the shear frequency of the mixed fluid increases, and the amount of bubbles generated increases.

[0075] The second projection 522 and the projection 512 may be located at the same position in the circumferential direction θ.

[0076] (Variation 2) Fig. 7 shows a modified example of the annular member. The annular member 53 of the first member 5 shown in Fig. 7 has a thickness T2 in the radial direction r that is thinner than the thickness T1 of the annular member 52 shown in Fig. 5 and the like. The thickness T2 is equal to the length L2 of the base 511 of the rod-shaped member 51. The annular member 53 forms a second protrusion 531 that protrudes inward in the radial direction r beyond the inner circumferential surface 214 of the tube 21 of the casing 2.

[0077] Like the second protrusions 521 and 522, this second protrusion 531 can cause gas to remain on the outer periphery in the radial direction r inside the casing 2. Since the retained gas becomes fine bubbles as the second member 6 rotates relative to one another, the second protrusion 531 in Fig. 7 also contributes to an increase in the amount of bubbles generated by the air bubble generation device 1.

[0078] In the air bubble generation device 1 of FIG. 7, the length L3 of the blade 612 of the second member 6 can be made longer than that shown in the figure, as long as it does not interfere with the annular member 53.

[0079] (Variation 3) Fig. 8 shows a modified example of the first member. The protrusion 541 of the first member 5 in Fig. 8 is continuous in the circumferential direction θ. Fig. 9 is a view of this modified example corresponding to Fig. 5.

[0080] 3, 4 and 5, the protrusion 512 of the first member 5 is formed by a rod-shaped member 51. In contrast to this, the protrusion 541 of the first member 5 in FIG. 8 is formed by an annular member 54. The annular member 54 has a thicker thickness T3 in the radial direction r (T3>T1) than the annular member 52 in FIG. 4. As shown in FIG. 9, the thickness T3 is set to a length that overlaps the blade 612 of the second member 6 in the radial direction r inside the casing 2.

[0081] The rod-shaped member 55 of the first member 5 does not have a protrusion, but only a base. The rod-shaped member 55 has an engagement portion 551. The engagement portion 551 is located in the axial direction X at the positions of the protrusions 512 of the rod-shaped member 51 in FIG. 4. The engagement portion 551 engages with a groove 543 of the annular member 54. The groove 543 is recessed radially inward from the outer periphery of the annular member 54. The number of annular members 54 in FIGS. 8 and 9 is greater than the number of annular members 52 in FIG.

[0082] 9, the blade 612 of the second member 6 is located between two annular members 54 adjacent to each other in the axial direction X. Between the annular members 54, a portion of the rod-shaped member 55 facing the blade 612 in the radial direction r forms a second protrusion 552 that protrudes inward in the radial direction r beyond the inner circumferential surface 214 of the tube 21 of the casing 2.

[0083] The protrusions 541 that are continuous in the circumferential direction θ interfere with the flow of the mixed fluid in the axial direction X, and increase the frequency of shearing of the mixed fluid that accompanies the relative rotation of the second member 6. This further increases the amount of bubbles generated.

[0084] (Variation 4) Fig. 10 shows a modified impeller. In the impeller 63 of Fig. 10, the blades 632 are continuous in the circumferential direction θ. Fig. 11 is a view of this modified example corresponding to Fig. 5.

[0085] The blades 632 extend outward in the radial direction r from the hub 631 around the entire circumference of the impeller 63. The impeller 63 has a disk shape as a whole.

[0086] The blades 632 that are continuous in the circumferential direction interfere with the flow of the mixed fluid in the axial direction X, and increase the frequency of shearing of the mixed fluid that accompanies the relative rotation of the second member 6. This further increases the amount of bubbles generated.

[0087] The structural features of the above-described embodiment and modifications 1 to 4 can be combined with each other to the extent possible.

[0088] (Variation 5) 12 shows a modified example of the outlet. In addition to the fluid outlet 213, the casing 2 may have a gas outlet 215. The gas outlet 215 is located on the outer circumferential surface of the second end of the cylinder 21. The gas outlet 215 protrudes outward in the radial direction r from the outer circumferential surface of the second end of the cylinder 21. The gas outlet 215 opens upward at the top of the cylinder 21.

[0089] As described above, the fluid outlet 213 located in the lower portion allows liquid containing fine bubbles to flow out. The gas outlet 215 located in the upper portion mainly allows gas accumulated in the upper portion of the interior of the cylinder 21 to flow out. The gas flowing out from the gas outlet 215 may be allowed to flow again into the cylinder 21 from the gas inlet 212. When the bubble generation device 1 is used for generating ozone water, for example, in addition to ensuring safety by being sealed, ozone gas can be efficiently dissolved in liquid.

[0090] (Variation 6) FIG. 13 shows a modified example of the outlet. The gas generating device 1 has a feature that the bubbles in the liquid are dissolved for a long time because the gas generating device 1 generates fine bubbles. Therefore, the gas bubble generating device 1 may include a tank 7 for the liquid containing fine bubbles. The dissolved state of the fine bubbles is maintained even while the liquid is stored in the tank 7. Storing the liquid containing fine bubbles in the tank 7 makes it possible to respond to an increase or decrease in the demand amount. As described later, the outlets 216 and 217 are in communication with the tank 7.

[0091] The tank 7 is formed by the lower part of the cylinder 21, a partition member 70, a side wall 71, and a support base 72. In the example of Fig. 13, the partition member 70 is a member having a U-shaped cross section, and is fixed to the underside of the cylinder 21 between the side wall 71 and the support base 72, as shown by the two-dot chain line in Fig. 13. The side wall 71 is fixed to a first end of the cylinder 21 and extends downward. The support base 72 supports the cylinder 21 and the prime mover 4.

[0092] A communication hole 218 is formed in a lower part of the outer circumferential surface at the second end of tube 21. Communication hole 218 connects the inside of tube 21 with the inside of tank 7. The liquid containing fine bubbles generated in tube 21 is sent to tank 7 through communication hole 218. Communication hole 218 is an example of an outlet. Tank 7 stores the liquid containing fine bubbles.

[0093] The outlet 216 is a fluid outlet 216, and the outlet 217 is a gas outlet 217. The fluid outlet 216 and the gas outlet 217 are each attached to the side wall 71 of the tank 7.

[0094] The fluid outlet 216 allows the liquid containing fine bubbles to flow out from inside the tank 7. The fluid outlet 216 is attached to the lower part of the side wall 71. The fluid outlet 216 attached to the lower part of the side wall 71 can allow the liquid containing fine bubbles to flow out even if the tank 7 is not filled with the liquid containing fine bubbles.

[0095] The gas flow outlet 217 allows gas separated inside the tank 7 to flow out of the tank 7. The gas flow outlet 217 is attached to the upper part of the side wall 71. The gas flow outlet 217 attached to the upper part can allow gas accumulated in the upper part of the tank 7 to flow out. The gas flow outlet 217 may be connected to the gas inlet 212.

[0096] (Other variations) The air bubble generation device 1 has a liquid inlet 211 and a gas inlet 212, and the liquid and the gas are separately supplied to the inside of the casing 2. Alternatively, a mixed fluid in which the liquid and the gas are mixed in advance may be supplied to the inside of the casing 2.

[0097] In the air bubble generation device 1, the casing 2 and the first member 5 are stationary and the shaft 3 and the second member 6 are rotating, but the casing 2 and the first member 5 may rotate and the shaft 3 and the second member 6 may be stationary. Alternatively, the casing 2 and the first member 5 may rotate and the shaft 3 and the second member 6 may rotate, for example, in the opposite direction. As the casing 2 and the first member 5 rotate, the shaft 3 and the second member 6 may rotate in the same direction as the casing 2 and the first member 5 but at a different speed. [Explanation of symbols]

[0098] 1. Air bubble generator 2 Casing 211 Liquid inlet 212 Gas inlet 213 Fluid Outlet 214 Inner surface 215 Gas outlet 216 Fluid Outlet 217 Gas outlet 218 Communication hole (outlet) 3 Shaft 5 First member 51 Rod-shaped member 512 Protrusion 52 Annular member 521 2nd protrusion 522 2nd protrusion 53 Annular member 531 2nd protrusion 54 Annular member 541 Protrusion 55 Rod-shaped member 552 2nd protrusion 6 Second member 612 Blade 632 Blade

Claims

1. a casing into which a mixed fluid of liquid and gas flows in an axial direction from an inlet to an outlet; a first member supported by the casing inside the casing; a second member supported by a shaft extending in the axial direction within the casing and rotating around the shaft relative to the first member, the second member having a blade extending from the shaft in a radial direction perpendicular to the axial direction and overlapping with the first member in the axial direction and the radial direction; The bubble generating device comprises:

2. The air bubble generating device according to claim 1, The first member has a plurality of projections that protrude in the radial direction from an inner surface of the casing and are spaced apart in the axial direction, The second member is located between the projections.

3. The air bubble generating device according to claim 2, The first member has a second projection located between the protrusions in the axial direction, protruding radially from the inner surface of the casing, and facing the second member.

4. The air bubble generating device according to claim 3, The second projection is continuous in the circumferential direction.

5. The air bubble generating device according to claim 2, The air bubble generation device, wherein the protrusions are arranged at intervals in the circumferential direction.

6. The air bubble generating device according to claim 1, The first member is A rod-shaped member extending in the axial direction; a ring-shaped member extending circumferentially along the inner surface of the casing, the ring-shaped member engaging with the rod-shaped member to position the rod-shaped member against the inner surface of the casing.

7. The air bubble generating device according to claim 1, The second member has a plurality of blades extending radially from the shaft in the radial direction.

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