Bubble generating device

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 a bubble generating device.

Background Art

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

[0003] Further, Patent Document 2 describes a conventional ultra-fine bubble generating tool that generates fine bubbles from the air dissolved in the liquid instead of mixing the sucked gas with the liquid. Specifically, this conventional generating tool includes a cylindrical member having a plurality of triangular prism-shaped protrusions. The cylindrical member rotates about an axis in the liquid. As the cylindrical member rotates, turbulent flow is generated by the protrusions, and the air contained in the liquid is miniaturized to generate ultra-fine bubbles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of 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 disk's rotation speed is increased, there is a limit to the amount of air that can be drawn in. The microbubble generator described in Patent Document 1 has difficulty producing a liquid containing a sufficient amount of microbubbles.

[0006] The ultrafine bubble generating device described in Patent Document 2 generates microbubbles from air dissolved in the liquid. However, for liquids with low dissolved air content, such as wastewater, this generating device cannot generate a sufficient amount of microbubbles. Furthermore, since this conventional generating device simply rotates a cylindrical member immersed in the liquid, there is a risk that only a swirling flow will occur around the cylindrical member, and a sufficient amount of microbubbles will not be generated.

[0007] The technology disclosed herein generates a liquid containing a sufficient amount of bubbles. [Means for solving the problem]

[0008] The technology disclosed herein relates to a bubble generating apparatus. This bubble generating apparatus is A casing through which a mixed fluid of liquid and gas supplied to the interior flows axially from the inlet to the outlet, Inside the casing, a first member supported by the casing, Within the casing, a second member is supported by a shaft extending in the axial direction and rotates relative to the first member around the shaft, the second member having a blade extending radially from the shaft perpendicular to the axial direction and overlapping with the first member in both the axial and radial directions, It is equipped with.

[0009] In this bubble generating apparatus, liquid and gas are supplied to the inside of the casing. The liquid and gas may be supplied to the inside of the casing individually, or a pre-mixed fluid of liquid and gas may be supplied to the inside of the casing. Inside the casing, the mixed fluid flows axially from the inlet to the outlet.

[0010] The bubble generating device comprises a first component, which is supported by a casing.

[0011] The bubble generating device includes a second member. The second member is supported by a shaft extending axially within the casing. The second member rotates around the shaft relative to the first member. The relative rotation between the first and second members may be achieved as follows: (1) the casing and the first member are stationary and the shaft and the second member rotate; (2) the casing and the first member rotate and the shaft and the second member are stationary; or (3) the casing and the first member rotate and the shaft and the second member 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. As the second member rotates relative to the first member, the mixed fluid is stirred between the blade and the first member, and bubbles are generated. The bubbles generated by this bubble generating device may be microbubbles with an average diameter of less than 100 μm and 1 μm or more, and fine bubbles including ultrafine bubbles with an average diameter of less than 1 μm. Alternatively, the bubbles generated by this bubble generating device may be larger than fine bubbles, i.e., bubbles with an average diameter of 100 μm or more.

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

[0014] The first member has a plurality of projections that protrude radially from the inner surface of the casing and are spaced apart in the axial direction. It is. The second member may be positioned between the protrusions.

[0015] This structure increases the number of shear points between the first and second members, which is advantageous for increasing the amount of bubbles generated. In addition, the multiple protrusions on the first member, which are aligned axially, and the second member between these protrusions, obstruct the axial flow of the mixed fluid, increasing the frequency of shearing of the mixed fluid as it flows from the inlet to the outlet. This increased shear frequency is also advantageous for the generation of fine bubbles and increases the amount of bubbles generated.

[0016] The first member is located between the protrusions in the axial direction and As a flow channel forming surface in contact with the mixed fluid From the inner surface of the casing, protruding in the radial direction and facing the second member It also has a circular inner surface Having a second projection ru.

[0017] Due to the centrifugal force generated by the relative rotation of the second member, the gas inside the casing tends to be pushed radially outward. The second projection, which is radially opposite to the second member, interferes with this gas and restricts its flow in the axial direction. The second projection causes gas to accumulate on the radial outer periphery inside the casing. The accumulated gas bubbles become fine bubbles as the relative rotation of the second member occurs. The second projection contributes to increasing the amount of bubbles generated by the bubble generator.

[0018] The second projection is the Orthogonal to the axial direction and the radial direction, respectively. is continuous in the circumferential direction ru.

[0019] The second protrusion that is continuous in the circumferential direction effectively restricts the flow of gas in the axial direction. More fine bubbles are generated.

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

[0021] With the relative rotation of the second member, a swirling flow centered on the shaft occurs inside the casing. The plurality of protrusions arranged at intervals in the circumferential direction interfere with the swirling flow and increase the shear frequency of the mixed fluid. The amount of generated bubbles further increases.

[0022] The first member Along the inner surface of the casing extends in the axial direction Together with the above-mentioned multiple protrusions rod-shaped member, an annular member that extends in the circumferential direction along the inner surface of the casing and positions the rod-shaped member on the inner surface of the casing by engaging with the rod-shaped member Together with, it constitutes the 2nd projection. and an annular member, may be included. <​​​​​​​​​​​​​​​​​​​​​​​As explained above, the bubble generating device can produce a liquid containing a sufficient amount of bubbles. [Brief explanation of the drawing]

[0027] [Figure 1] Figure 1 is a perspective view of the bubble generation device. [Figure 2] Figure 2 is an exploded view of the bubble generation device. [Figure 3] Figure 3 shows the front view (left) and side view (right) of the first member. [Figure 4] Figure 4 shows the front view and cross-sectional view AA of the rod-shaped member, and the front view and side view of the annular member and impeller, respectively. [Figure 5] Figure 5 shows a cross-sectional view of the inside of the casing (left) and a cross-sectional view of the BB (right). [Figure 6] Figure 6 shows a cross-sectional view (left) and a cross-sectional view (right) of the inside of the casing according to a modified example. [Figure 7] Figure 7 shows a cross-sectional view (left) and a cross-sectional view (right) of the inside of the casing according to a modified example. [Figure 8] Figure 8 shows a front view of the rod-shaped member, a side view of the annular member, and an EE cross-sectional view of the modified part. [Figure 9] Figure 9 shows a cross-sectional view (left) and an FF cross-sectional view (right) of the inside of the casing according to a modified example. [Figure 10] Figure 10 is a side view of the second member according to a modified example. [Figure 11] Figure 11 shows a cross-sectional view (left) and a cross-sectional view (right) of the inside of the casing according to a modified example. [Figure 12] Figure 12 is a perspective view of a modified bubble generating device. [Figure 13] Figure 13 is a perspective view of a bubble generating apparatus according to yet another modified example. [Modes for carrying out the invention]

[0028] The following describes an embodiment of the bubble generating apparatus with reference to the drawings. The bubble generating apparatus described here is illustrative.

[0029] (Overall structure of the bubble generation device) Figure 1 shows the overall structure of the bubble generator 1. The bubble generator 1 generates bubbles in a liquid. The bubble generator 1 is used in wastewater treatment facilities. Specifically, the bubble generator 1 generates fine bubbles of air in the liquid to be treated. When fine bubbles are generated, the dissolved oxygen concentration in the liquid increases. In addition, if the liquid to be treated contains solid matter, the fine bubbles in the liquid adhere to the solid matter, making it possible to float and recover the solid matter.

[0030] Here, the bubbles generated by the bubble generator 1 may include microbubbles with an average diameter of less than 100 μm and 1 μm or more, and fine bubbles including ultrafine bubbles with an average diameter of less than 1 μm. Furthermore, the bubbles generated by this bubble generator 1 may be larger than fine bubbles, i.e., bubbles with an average diameter of 100 μm or more.

[0031] Figure 2 is an exploded perspective view of the bubble generating device 1. The bubble generating device 1 includes a casing 2. The casing 2 houses the first member 5 and the second member 6, which will be described later. The bubble generating device 1 stirs the mixed fluid of liquid and gas by the relative rotation of the first member 5 and the second member 6 inside the casing 2, and mechanically refines the generated bubbles into fine bubbles.

[0032] The casing 2 has a cylinder 21. The cylinder 21 is a cylinder that extends along the axis of the bubble generating device 1. The first end and the second end opposite the first end are open. The first end is the front right end in Figure 2, and the second end is the back left end in Figure 2. The cylinder 21 may also be a split structure formed by joining two members that are divided along a center line.

[0033] In the following explanation, the direction in which the axis of the cylinder 21 extends will be referred to as the axial direction X, and in Figures 1 and 2, the direction from the front right of the page to the back left of the page will be considered the positive direction of the axial direction X. The positive direction of the axial direction X corresponds to the main flow direction of the fluid in the bubble generating 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 radially outward r from the outer circumferential surface of the first end of the cylinder 21. Here, the radial direction r is perpendicular to the axial direction X, and the direction outward 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 forces a liquid, such as water, into 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 perpendicular to the axial direction X and the radial direction r, and the rotation direction of the prime mover 4, which will be described later, is defined as the positive direction of the circumferential direction θ. The gas inlet 212 is a tube that communicates with the inside of the cylinder 21 and protrudes radially outward 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 forces a gas, such as air, into the casing 2 through the gas inlet 212.

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

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

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

[0039] Casing 2 has a second cover 23. The second cover 23 is fitted to the opening at the second end of the cylinder 21. The second cover 23 has a through hole 231 extending in the axial direction X. The second end 33 of the shaft 3 passes through the second cover 23. The second cover 23 also supports a second bearing 25. The second bearing 25 rotatably supports the second end 33 of the shaft 3. The second cover 23 also houses a seal 26 within the through hole 231. The seal 26 makes casing 2 watertight by sealing around the second end 33 of the shaft 3. The seal 26 is, for example, a mechanical seal. The seal 26 is not limited to a particular structure.

[0040] The bubble generator 1 includes a shaft 3. The shaft 3 extends along the axial direction X. The shaft 3 is inserted into the cylinder 21 of the 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 that extend along the axial direction X from the end of the support portion 31. 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 in the casing 2. In other words, the shaft 3 can rotate relative to the casing 2.

[0041] The bubble generating device 1 is equipped with 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. The output shaft 41 of the prime mover 4 is coupled to the second end 33 of the shaft 3 inside the second cover 23. The prime mover 4 rotates the shaft 3. The prime mover 4 may also be coupled to the first end 32 of the shaft 3.

[0042] The bubble generating device 1 includes a first member 5. The first member 5 is supported by the casing 2. The bubble generating device 1 also includes a second member 6. The second member 6 is supported by the 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 work together to generate bubbles inside the casing 2. Details of the structures of the first member 5 and the second member 6 will be described later.

[0043] (Structure of the first member) Figure 3 shows the first member 5. The outer circumference of the first member 5 in the radial direction r is circular in a side view as shown in the right-hand diagram of Figure 3, and 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 cylinder 21 of the casing 2 (see also Figure 5). The first member 5 is supported by the cylinder 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 does not have to be fixed to the casing 2. If the first member 5 is not fixed to the casing 2, for example, it will be easier to replace the first member 5 when it deteriorates. Even if the first member 5 is not fixed to the casing 2, due to the weight of the first member 5, the first member 5 will not, or will not substantially, rotate relative to the casing 2 when the bubble generating device 1 is in operation.

[0045] The first member 5 is composed of a rod-shaped member 51 and an annular member 52. Figure 4 illustrates the rod-shaped member 51 and the annular member 52.

[0046] The rod-shaped members 51 extend in the axial direction X. Multiple rod-shaped members 51 are arranged at equal intervals in the circumferential direction θ along the inner surface of the cylinder 21.

[0047] The rod-shaped member 51 has a base 511 and a plurality of projections 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 cylinder 21 (see also Figure 5). Each of the plurality of projections 512 protrudes inward from the base 511 in the radial direction r. The projection length L1 of the projection 512 is sufficiently longer than the radial length L2 of the base 511. As will be described later, the projection length L1 of the projection 512 is set to a length that overlaps the projection 512 and the blade 612 of the second member 6 in the radial direction r (see also Figure 5).

[0048] Multiple protrusions 512 are arranged at equal intervals along the axial direction X. The number of protrusions 512 can be set to an appropriate number.

[0049] The base 511 has engaging portions 513. The engaging portions 513 are located between adjacent projections 512 in the axial direction X. More precisely, the engaging portions 513 are located at every other projection in the axial direction X, rather than at all points between adjacent projections 512. The engaging portions 513 are recesses that are recessed radially r outward from the end of the base 511. The engaging portions 513 engage with the annular member 52.

[0050] The annular member 52 has an annular shape. The annular member 52 extends circumferentially along the inner circumferential surface 214 of the cylinder 21 of the casing 2. The annular member 52 has a radial thickness T1 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 edge of the annular member 52. The grooves 523 are positioned at equal intervals in the circumferential direction θ on the annular member 52. The grooves 523 are the parts that engage with the engaging portion 513 of the rod-shaped member 51 (see the dashed arrow in Figure 4). The number of grooves 523 corresponds to the number of rod-shaped members 51 that constitute the first member 5.

[0052] As shown in Figures 2, 3, or 4, the annular member 52 is positioned radially r inward relative to the rod-shaped members 51, which are arranged at equal intervals in the circumferential direction θ. Figure 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 members 51, causing the rod-shaped members 51 to be sandwiched between the inner circumferential surface 214 of the cylinder 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 members 51. The annular members 52 are arranged at equal intervals in the axial direction X.

[0053] Each projection 512 of the rod-shaped member 51 protrudes inward in the radial direction r from the inner circumferential surface 214 of the cylinder 21. The projections 512 are arranged at equal intervals in the axial direction X, as shown in the left diagram of Figure 3, and also at equal intervals in the circumferential direction θ, as shown in the right diagram of Figure 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-hand diagram of Figure 5, the annular member 52 forms a second projection 521 that protrudes radially inward from the base 511 in the radial direction r. The length of the second projection 521 (T1-L2) is shorter than the length of the projection 512 (L1). The second projection 521 is located between adjacent projections 512 in the axial direction X. As mentioned above, the annular member 52 that engages with the engaging portion 513 of the base 511 is not located in all the spaces between adjacent projections 512. Therefore, the second projection 521 is located between adjacent projections 512 at every other point in the axial direction X.

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

[0056] (Structure of the second member) Figure 2 shows the second member 6. As shown by the dashed line in the right-hand diagram of Figure 3, the outer circumference of the second member 6 in the radial direction r is substantially circular in a side view. The second member 6 is externally fitted onto the shaft 3 and supported by the shaft 3. The second member 6 rotates around the axis of the bubble generating device 1 as the shaft 3 rotates.

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

[0058] As shown in Figure 4, the impeller 61 has a hub 611 and a plurality of blades 612. The hub 611 has a through hole that is fitted onto the support portion 31 of the shaft 3. Reference numeral 613 denotes a keyway. The impeller 61 rotates together with the shaft 3.

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

[0060] As shown in Figure 2 or the right-hand diagram of Figure 5, the spacer 62 is interposed between the impellers 61 in the axial direction X. The spacer 62 is annular and is externally 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, as shown in Figure 5, the impellers 61 overlap with the projections 512 of the first member 5 in the axial direction X and are positioned between the projections 512 of the first member 5. The blades 612 of the impeller 61 are also facing the annular member 52 radially r at every other axial position X.

[0061] As mentioned above, multiple impellers 61 are attached to the shaft 3. When multiple impellers 61 are attached to the shaft 3, the blades 612 are located at the same circumferential position θ for multiple impellers 61 aligned in the axial direction X (see the dashed line in the right diagram of Figure 3). In other words, the blades 612 are located in overlapping positions in the axial direction X for multiple impellers 61. However, the blades 612 may be located at different circumferential positions θ for multiple impellers 61. That is, when viewing the second member 6 from its first end along the axial direction X, the blades 612 of the multiple impellers 61 may be located alternately. As will be described later, the alternate arrangement of the blades 612 restricts the flow of the mixed fluid in the axial direction X, which is advantageous for the generation of fine bubbles by increasing the shear frequency.

[0062] (Operation of the bubble generation device) The bubble generator 1 receives liquid from the liquid inlet 211 and gas from the 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. As the second member 6 rotates relative to the first member 5, the mixed fluid inside the casing 2 is stirred, and bubbles are generated.

[0063] The blade 612 of the second member 6, which rotates relative to the first member 5, shears the mixed fluid in the circumferential direction θ and radial direction r between it and the projection 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 bubble generating device 1 can produce a liquid containing a sufficient amount of bubbles compared to conventional devices. The liquid containing 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 multiple 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 points between the first member 5 and the second member 6, thereby increasing the amount of bubbles generated. Furthermore, the multiple protrusions 512 and multiple blades 612 aligned in the axial direction X obstruct the flow of the mixed fluid in the axial direction X, increasing the frequency of shearing of the mixed fluid. This increase in shearing frequency also increases the amount of bubbles generated.

[0065] Multiple protrusions 512 on the first member 5 are arranged at intervals in the circumferential direction θ. As the second member 6 rotates relative to the first member 5, a swirling flow is generated inside the casing 2 centered on the shaft 3. The multiple protrusions 512, which are spaced apart in the circumferential direction θ, interfere with the swirling flow, increasing the shearing frequency 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 in multiples with spacing between them in the circumferential direction θ. Each of the multiple blades 612 rotating relative to one another shears the mixed fluid between itself and the projection 512. This increases the amount of bubbles generated.

[0067] The first member 5 further has a second projection 521. The second projection 521 is located between the projections 512 and protrudes radially r from the inner circumferential surface 214 of the casing 2, facing 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 pushed outward in the radial direction r (see the arrow in the right diagram of Figure 5). The second projection 521, which faces the blade 612 radially r, interferes with this gas and restricts the flow of the gas in the axial direction X. The second projection 521 causes the gas to accumulate on the outer circumference radially r inside the casing 2. The accumulated gas becomes fine bubbles as the relative rotation of the second member 6 occurs. The second projection 521 contributes to increasing the amount of bubbles generated by the bubble generating device 1.

[0068] Furthermore, the second projection 521 is continuous in the circumferential direction θ, as shown in the left diagram of Figure 5. The second projection 521, which is continuous in the circumferential direction θ, effectively restricts the flow of gas in the axial direction X. Because gas accumulates on the outer circumference in the radial direction r, more fine bubbles are generated.

[0069] The bubble generator 1 has a larger flow path compared to conventional bubble generators. The larger flow path of the bubble generator 1 has the advantage of being able to treat turbid water directly, making it suitable for use in wastewater treatment. Furthermore, by adding activated carbon powder to the inside of the casing 2, the activated carbon effect, such as reducing the COD (Chemical Oxygen Demand) of wastewater and decolorizing it, is improved.

[0070] The bubble generator 1 can also produce ozonated water by generating fine bubbles of ozone. Ozonated water can be used, for example, to purify enclosed water bodies. Furthermore, by utilizing the high oxidizing power of ozonated water, the ozonated water produced by the bubble generator 1 can also be used for washing, deodorizing, or decolorizing. The bubble generator 1 can seal the supplied gas inside the casing 2. The bubble generator 1 can suppress the leakage of ozone into the atmosphere, ensuring high safety, and can dissolve expensive ozone gas in water with high efficiency.

[0071] Furthermore, the applications of the bubble generator 1 are not limited to wastewater treatment. The bubble generator 1 has a variety of applications.

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

[0073] Multiple second protrusions 522, spaced apart in the circumferential direction θ, interfere with the swirling flow inside the casing 2. This increases the amount of bubbles generated.

[0074] Furthermore, as shown in the left diagram of Figure 6, in the first member 5, the second projection 522 and the projection 512 are misaligned in the circumferential direction θ. The misalignment of projection 512 and the second projection 522 in the circumferential direction θ obstructs the axial flow X of the mixed fluid. As mentioned above, the shearing frequency of the mixed fluid increases, and the amount of bubbles generated increases.

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

[0076] (Modification 2) Figure 7 shows a modified example of the annular member. The annular member 53 of the first member 5 shown in Figure 7 has a thickness T2 in the radial direction r that is thinner than the thickness T1 of the annular member 52 shown in Figure 5, etc. 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 projection 531 that protrudes radially r inward from the inner circumferential surface 214 of the cylinder 21 of the casing 2.

[0077] Similar to the second protrusions 521 and 522 described above, this second protrusion 531 can also allow gas to accumulate on the outer circumference in the radial direction r inside the casing 2. As the accumulated gas rotates relative to the second member 6, the second protrusion 531 in Figure 7 also contributes to increasing the amount of bubbles generated by the bubble generating device 1.

[0078] Furthermore, in the bubble generating apparatus 1 shown in Figure 7, the length L3 of the blade 612 of the second member 6 can be made longer than shown in the example, as long as it does not interfere with the annular member 53.

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

[0080] More specifically, in Figures 3, 4, and 5, the projection 512 of the first member 5 was formed by a rod-shaped member 51. In contrast, the projection 541 of the first member 5 in Figure 8 is formed by an annular member 54. The annular member 54 has a thicker radial thickness T3 (T3 > T1) compared to the annular member 52 in Figure 4. As shown in Figure 9, the thickness T3 is set to overlap radially with respect to the blade 612 of the second member 6 within the casing 2.

[0081] The rod-shaped member 55 of the first member 5 has no projections and only a base. The rod-shaped member 55 has an engaging portion 551. The engaging portion 551 is located in the axial direction X at the positions of the projections 512 on the rod-shaped member 51 in Figure 4. The engaging portion 551 engages with the groove 543 of the annular member 54. The groove 543 is recessed radially inward from the outer edge of the annular member 54. There are more annular members 54 in Figures 8 and 9 than there are annular members 52 in Figure 5.

[0082] As shown in Figure 9, the blade 612 of the second member 6 is located between two adjacent annular members 54 in the axial direction X. Between the annular members 54, the portion of the rod-shaped member 55 facing the blade 612 in the radial direction r forms a second projection 552 that protrudes radially inward r from the inner circumferential surface 214 of the cylinder 21 of the casing 2.

[0083] The continuous projections 541 in the circumferential direction θ interfere with the flow of the mixed fluid in the axial direction X, increasing the frequency of shearing of the mixed fluid due to the relative rotation of the second member 6. This further increases the amount of bubbles generated.

[0084] (Modification 4) Figure 10 shows a modified version of the impeller. In the impeller 63 of Figure 10, the blades 632 are continuous in the circumferential direction θ. Figure 11 is a diagram of this modified version corresponding to Figure 5.

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

[0086] The circumferentially continuous blades 632 interfere with the flow of the mixed fluid in the axial direction X, increasing the frequency of shearing of the mixed fluid due to the relative rotation of the second member 6. This further increases the amount of bubbles generated.

[0087] Furthermore, the structural features of the embodiments described above, as well as those of Modifications 1 to 4, can be combined with each other to the extent possible.

[0088] (Variation 5) Figure 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 radially outward 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 mentioned above, the fluid outlet 213 located in the lower part discharges liquid containing fine bubbles. The gas outlet 215 located in the upper part mainly discharges gas that has accumulated in the upper part of the inside of the cylinder 21. The gas discharged from the gas outlet 215 may be reintroduced into the cylinder 21 through the gas inlet 212. When the bubble generator 1 is used, for example, to produce ozonated water, in addition to ensuring safety through sealing, ozone gas can be efficiently dissolved in the liquid.

[0090] (Experimental variation 6) Figure 13 shows a modified example of the outlet. The gas generator 1 generates fine bubbles, and therefore has the characteristic of having a long dissolution time for bubbles in the liquid. For this reason, the bubble generator 1 may be equipped with a tank 7 for liquid containing fine bubbles. The dissolved state of the fine bubbles is maintained even while stored in the tank 7. The storage of liquid containing fine bubbles in the tank 7 makes it possible to respond to increases and decreases in demand. As will be 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 shown in Figure 13, the partition member 70 is a U-shaped member in cross-section and is fixed to the lower side of the cylinder 21 between the side wall 71 and the support base 72, as shown by the dashed line in Figure 13. The side wall 71 is fixed to the 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 at the lower part of the outer circumferential surface at the second end of the cylinder 21. The communication hole 218 connects the inside of the cylinder 21 to the inside of the tank 7. The liquid containing the fine bubbles generated in the cylinder 21 is sent to the tank 7 through the communication hole 218. The communication hole 218 is an example of an outlet. The tank 7 stores the liquid containing the fine bubbles.

[0093] Outlet 216 is a fluid outlet 216, and 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 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 liquid containing fine bubbles to flow out even if the tank 7 is not filled with liquid containing fine bubbles.

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

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

[0097] In the bubble generating device 1, the casing 2 and the first member 5 are stationary, and the shaft 3 and the second member 6 rotate. However, the casing 2 and the first member 5 may rotate, and the shaft 3 and the second member 6 may remain 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 opposite directions. The casing 2 and the first member 5 may rotate, and 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 different speeds. [Explanation of symbols]

[0098] 1. Bubble generating device 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 shafts 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 Blades 632 blades

Claims

1. A casing through which a mixed fluid of liquid and gas supplied to the interior flows axially from the inlet to the outlet, Inside the casing, a first member supported by the casing, Within the casing, a second member is supported by a shaft extending in the axial direction and rotates relative to the first member on the shaft, the second member having a blade extending radially from the shaft perpendicular to the axial direction and overlapping with the first member in both the axial and radial directions, Equipped with, The first member has a plurality of projections that protrude radially from the inner surface of the casing and are spaced apart in the axial direction, and a second projection that is located between the projections in the axial direction and protrudes radially from the inner surface of the casing, which is a flow path forming surface in contact with the mixed fluid, and faces the second member, and has a circumferential inner surface. The bubble generating device wherein the second projection is continuous in a circumferential direction perpendicular to the axial direction and the radial direction, respectively.

2. In the bubble generating apparatus according to claim 1, The second member is a bubble generating device located between the protrusions.

3. In the bubble generating apparatus according to claim 1, The aforementioned protrusions are arranged in a plurality at intervals in the circumferential direction, forming a bubble generating device.

4. In the bubble generating apparatus according to claim 1, The first member is, A rod-shaped member that extends in the axial direction along the inner surface of the casing and constitutes the plurality of protrusions, A bubble generating device comprising an annular member that extends circumferentially along the inner surface of the casing, which engages with the rod-shaped member to position the rod-shaped member on the inner surface of the casing, and which also constitutes the second projection.

5. In the bubble generating apparatus according to claim 1, The second member is a bubble generating device having a plurality of blades that extend radially from the shaft.

6. In the bubble generating apparatus according to claim 5, The second projection is a bubble generating device facing the blade.

7. A casing through which a mixed fluid of liquid and gas supplied inside flows axially from the inlet to the outlet, Inside the casing, a first member supported by the casing, Within the casing, a second member is supported by a shaft extending in the axial direction and rotates relative to the first member on the shaft, the second member having a blade extending radially from the shaft perpendicular to the axial direction and overlapping with the first member in both the axial and radial directions, Equipped with, The first member is, A rod-shaped member extending in the axial direction along the inner surface of the casing, A bubble generating apparatus comprising: an annular member extending circumferentially along the inner surface of the casing, which engages with the rod-shaped member to position the rod-shaped member on the inner surface of the casing.

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