JP2008246361A - Microbubble generation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microbubble generation apparatus capable of generating very fine bubbles independently of the pressure of a gas to be supplied or the flow rate of a liquid. <P>SOLUTION: The microbubble generation apparatus comprises a bubble releasing body 8 with bubble releasing holes on a bubble releasing surface, a main body casing 9 for holding the bubble releasing body 8, a gas chamber 11 communicated with the bubble releasing holes, an air supply pipeline 7 for supplying the gas to the gas chamber 11, and an underwater motor device 4 for moving the bubble releasing body 8 relatively to the liquid. The coating layer 10 of the bubble releasing surface 8b of the bubble releasing body 8 comprises a blade part 10a projected from the bubble releasing surface 8b into the relative flow of the liquid and a releasing hole closing part 10b including a prescribed radius area from the rotation center of the bubble releasing body. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a microbubble generator, and relates to a technique for mixing microbubbles in a liquid.

  Conventionally, as a method of mixing fine bubbles in a liquid, for example, as described in Patent Document 1, a gas such as ozone is sent into a ceramic cylinder at a high pressure, and bubbles are formed from the ceramic holes as external water. There is something that is sent to the liquid and dissolved. However, there is a problem that the gas pressure has to be increased as the pore diameter of the ceramic is reduced for the purpose of reducing the bubble diameter.

  For this reason, Patent Document 1 discloses a configuration that does not depend on the gas pressure but depends on the force of the liquid vortex. That is, an outer cylinder is concentrically arranged outside the ceramic cylinder, a narrow flow path is formed between the ceramic cylinder and the outer cylinder, and a liquid is allowed to flow through the flow path at a high speed so as to exceed the critical Reynolds number. The surface tension of bubbles is broken by fine vortices generated by the turbulent flow of gas, and fine bubbles of gas are continuously dissolved in the liquid. Further, as a configuration for further strengthening the vortex of the liquid, spiral fine irregularities are formed on the inner surface of the outer cylinder arranged outside the ceramic cylinder.

  Patent Document 2 describes a microbubble generator, a polluted water purifier, and a polluted water purifying method. This bubble generating device is provided in a liquid and includes a stirring fin and a supply pipe for supplying air. One end of the supply pipe opens as a supply port at the center of the stirring fin, and the other end of the supply pipe Is opened to the gas supply source as an intake hole. Then, a negative pressure is generated around the stirring fin while the surrounding liquid is stirred by the rotation of the stirring fin, and a gas is sucked from the supply pipe by this negative pressure to generate bubbles.

  A baffle plate made of a plate-like body is provided on the outside of the rotating stirring fin, and a plurality of baffle plates are erected so as to disturb the stirring of the liquid by the stirring fin, and the baffle plates are connected and fixed with a fixed plate. The stirring fin is included, and a perforated plate is provided outside the stirring fin in the radial direction. The gas sucked from the supply port is finely divided by the stirring fin, the perforated plate, and the baffle plate and supplied to the liquid.

Patent Document 3 describes a bubble diameter control type underwater bubble generator. This includes an airtight water tank having a water supply pump and a discharge pump, a decompression pump for decompressing the airtight water tank, a bubble discharge device for generating bubbles in the decompressed airtight water tank, and a discharge pump disposed outside the airtight water tank. And a water tank that is connected to the airtight water tank and micronizes the bubbles generated in the decompressed airtight water tank under atmospheric pressure, and the bubble discharge device has a microporous material disposed on the outer peripheral portion of the rotating plate.
WO2002 / 036252 JP 2006-82072 A Japanese Patent Laid-Open No. 9-5204

  By the way, in Patent Document 1, an outer cylinder is arranged concentrically outside the ceramic cylinder, a narrow flow path is formed between the ceramic cylinder and the outer cylinder, and a liquid is allowed to flow through the flow path at a high speed. In the case where there is a narrow channel between the ceramic cylinder and the outer cylinder, the flow rate of the liquid that can be supplied through this channel is limited. When the flow paths of the ceramic cylinder and the outer cylinder are enlarged so that a large amount of liquid can be supplied, it is necessary to increase the pump power in order to supply a large amount of liquid at a flow rate necessary for generating vortices.

  Moreover, even when a spiral fine uneven portion is formed on the inner surface of the outer cylinder, if the distance between the uneven portion and the ceramic cylinder that discharges the bubbles is increased, the vortex action hardly reaches the surface from which the bubbles are discharged. In addition, as described in Patent Document 2, when the gas sucked from the supply port is finely divided by the stirring fin, the perforated plate and the baffle plate and supplied into the liquid, the original gas sucked from the supply port is supplied. Since the bubble diameter is large, there is a limit to the refinement of bubbles that can be achieved by transient collisions with stirring fins, perforated plates, and baffle plates.

  Further, as described in Patent Document 3, when the bubble releasing device has a microporous material arranged on the outer peripheral portion of the rotating plate, a water flow flows along the surface of the flat microporous material. There is no guarantee that the bubbles ejected from the pore material will be surely separated from the surface of the microporous material, and the coalescence of the bubbles may occur.

  The present invention solves the above-described problems, and an object of the present invention is to provide a fine bubble generating device that can generate fine bubbles without depending on the pressure of a supplied gas and the flow rate of a liquid.

  In order to solve the above problems, a microbubble generator of the present invention includes a bubble emitter having a plurality of bubble discharge holes on a bubble discharge surface that forms an interface with a liquid, and an emitter holding means for holding the bubble emitter. A gas chamber communicating with the bubble discharge hole, a gas supply means for supplying gas to the gas chamber, and a relative movement for moving the bubble discharger relative to the liquid and generating a relative flow of the liquid on the bubble discharge surface The bubble emitting body has a coating layer on the bubble emitting surface for preventing the release of bubbles, and the coating layer protrudes from the bubble emitting surface into the relative flow of the liquid and has a predetermined surface on the bubble emitting surface. It is characterized by forming a protruding portion of the form.

  Further, the relative driving means comprises a rotation driving device that rotationally drives the bubble emitter around the axis of the drive shaft, and a region within a predetermined radius from the rotation center of the bubble emitter is a non-discharge hole region that does not have a bubble discharge hole. It is characterized by making.

  Further, on the bubble discharge surface outside the non-release hole region, the surface flow velocity of the relative flow generated by the rotation of the bubble discharge member is a predetermined flow velocity that suppresses the coalescence of bubbles ejected from the bubble discharge surface. Features.

  In the bubble emitter, the non-discharge hole region occupies an inner region of a diameter D1 passing through the rotation axis of the bubble emitter, and the bubble discharge surface outside the non-release hole region is the rotation axis of the bubble emitter. It occupies the outer region of the direct line D2 passing through the heart, and the diameter ratio D1 / D2 between the diameter D1 of the inner region and the diameter D2 of the outer region is 0.7 or more.

In addition, the non-release hole region is formed of a coating layer that prevents the release of bubbles formed on the bubble release surface.
Further, the protruding portion formed on the bubble discharge surface is characterized in that it has a blade shape formed radially around the rotation axis of the bubble emitter or a form formed by a plurality of convex bodies.

  Further, the bubble emitting body is made of a carbon material, a ceramic porous body, or a sintered metal.

  As described above, according to the present invention, the bubble emitter is moved with respect to the liquid by the relative driving means to generate a relative flow of the liquid on the bubble discharge surface. The gas supplied to the gas chamber by the gas supply means is ejected into the liquid from the bubble discharge surface that forms an interface with the liquid through the bubble discharge hole. At this time, the bubble discharge surface moves relative to the liquid, so that the gas ejected from the bubble discharge surface into the liquid is ejected as fine bubbles, and the protrusions of the coating layer are on the bubble discharge surface. A turbulent flow is generated in the relative flow, and the turbulent flow is surely applied to the gas ejected from the bubble discharge hole.

  In the present invention, when the bubbles are ejected from the bubble discharge holes, the bubbles already have a fine bubble diameter, and the turbulent flow acting on the bubble discharge surface causes the fine bubbles ejected from the bubble discharge holes to be near the bubble discharge holes. From quickly. For this reason, coalescence of bubbles can be suppressed, and fine bubbles can be generated without depending on the pressure of the supplied gas and the flow rate of the liquid.

  Further, since the protruding body is formed by the coating layer, it is not necessary to form the protruding body integrally with the bubble emitting body or to be formed and attached as a separate member, and can be easily formed. In addition, the shape of the protrusion can be easily changed according to the application and use conditions.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the fine bubble generating device 1 of the present embodiment is a case where it is placed in water such as a water tank or a water channel, and rotates as a relative driving means on a leg 3 placed on a bottom wall surface 2. An underwater motor device 4 is provided as a driving device. The rotation drive device is not limited to the submersible motor device 4, and an engine device or the like can be used as appropriate.

  A bubble discharge unit 6 is connected to the drive shaft 5 of the submersible motor device 4, and the bubble discharge unit 6 is rotatably connected to an air supply line 7 as a gas supply means. The air supply line 7 is supplied with air. Connected to the source. In the present embodiment, the liquid is water and the gas is air. However, the present invention is not limited to water and air.

  Further, the fine bubble generating device 1 can be installed outside the water tank as shown in FIG. 7, and when installed in the water tank as shown in FIG. A structure in which the path 7 penetrates the underwater motor device 4 and is connected to the bubble discharge unit 6 is also possible. Further, the bubble discharge surface is not limited to the downward direction, and may be disposed upward or inclined.

As shown in FIGS. 2 to 5, the bubble discharger 6 includes a bubble discharger 8 and a main body casing 9 that forms discharger holding means, and a coating layer 10 is formed on the bubble discharger 8.
As shown in FIG. 3, the main casing 9 has a coupling hole 9 a and a key groove 9 b for connecting to the drive shaft 5 of the submersible motor device 4, and a recess formed inside forms a gas chamber 11, The bubble emitting body 8 is fixedly held on the opening side of 11. Spacers 12 for maintaining a gap with the bubble emitter 8 are formed radially around the coupling hole 9 a inside the main body casing 9. The gas chamber 11 communicates with the bubble discharge hole of the bubble emitter 8, and the air supply line 7 communicates with the gas chamber 11.

  As shown in FIG. 4, the bubble emitter 8 has a disk-like shape made of a porous body, has a vent hole 8 a in the center, and is formed on the bubble discharge surface 8 b that forms an interface with water. The coating layer 10 is made of an epoxy resin or the like that prevents the release of water. The bubble emitter 8 of the present embodiment is a porous body made of a carbon material, but ceramic or sintered metal can be used for the bubble emitter 8. The sintered metal may be a powder metal sintered body or a metal mesh sintered body.

  In the coating layer 10, a blade portion 10 a that forms a protrusion that protrudes from the bubble discharge surface 8 b into the relative flow of water is formed on the surface of the bubble discharge surface 8 b in a predetermined shape. In the predetermined radius region, the non-discharge hole region 10b is formed so as to cover the bubble discharge surface 8b.

  In the coating layer 10, the non-discharge hole region 10 b occupies the inner region of the diameter D <b> 1 passing through the rotational axis of the bubble emitter 8, and the bubble discharge surface 8 b outside the non-release hole region 10 b is the rotation of the bubble emitter 8. It occupies the outer region of the direct system D2 passing through the axis, and the diameter ratio D1 / D2 between the diameter D1 of the inner region and the diameter D2 of the outer region can be 0.7 or more. This value will be described in detail later.

  A plurality of bubble discharge holes for discharging bubbles are regularly or irregularly arranged on the bubble discharge surface 8b. This bubble discharge hole is configured so that fine bubbles can be ejected by setting it to a minute predetermined diameter corresponding to the bubble diameter of the air discharged into the water. In the present embodiment, the bubble diameter is several tens of μm, the diameter of the bubble discharge hole is 0.4 to 5 μm, the porous body has a porosity of 12 to 35%, and the maximum use pressure is 0.6 MPa.

  The bubble emitter 8 includes a disk portion 14 that is fixed to the main body casing 9 with bolts 13 (see FIG. 2), and a hub 15 that is connected to the air supply pipe 7. The hub 15 communicates with the through hole 8a. The blade portion 10a of the coating layer 10 includes a plurality of blades 16 that form a turbulent flow promoting means having a connecting hole 15a and are arranged radially around the hub 15, and air is supplied through the shaft seal 17 in the connecting hole 15a. The pipe 7 is rotatably connected.

  With this configuration, the submersible motor device 4 serving as a relative drive means rotates the bubble discharger 6 around the axis of the drive shaft 5 by the rotation of the drive shaft 5, and the bubble emitter 8 is relative to water in water. And a relative flow of water is generated on the surface of the bubble discharge surface 8b.

  The air that has flowed into the gas chamber 11 from the air supply pipe 7 passes through the bubble discharge holes of the bubble discharger 8 and is ejected as microbubbles onto the surface of the bubble discharge surface 8b that forms an interface with water, and the bubble discharge surface 8b. As the water moves in the water, the relative flow flowing along with the vortex on the surface of the bubble discharge surface 8b entrains and separates the microbubbles and suppresses the coalescence of the bubbles.

  As shown in FIG. 5, the blade portion 10 a of the bubble emitter 8 diffuses the bubbles around by the hydraulic action of the blade 16. That is, the blade 16 disturbs the flow of the relative flow on the surface of the bubble discharge surface 8b, and the turbulent flow with the vortex flow is surely generated on the surface of the bubble discharge surface 8b. On the other hand, turbulent flow can be reliably applied.

  By the way, the bubble emitting body 8 becomes so slow that the peripheral speed (linear velocity) in each position on the surface of the bubble discharge | release surface 8b is a rotation center side. For this reason, the surface flow velocity of the relative flow of water generated on the surface of the bubble discharge surface 8b by the rotation of the bubble discharger 8 becomes slower as it approaches the rotation axis of the bubble discharger 8, and the rotation axis of the bubble discharger 8 The faster you get away from your heart, the faster it gets.

  For this reason, the closer to the center of rotation of the bubble emitter 8, the weaker the discrete and diffusing action exerted on the microbubbles ejected from the bubble emitter hole of the bubble emitter 8, and the coarser bubbles due to the coalescence of the microbubbles Tend to be.

  As a result, the bubbles supplied to the water as the fine bubble generating device 1 have irregular bubble diameters, the uniformity of the bubble diameters is hindered, and for example, the bubbles having the bubble diameters required for the water treatment process cannot be stably supplied.

  For this reason, in the present embodiment, the coating layer 10 that forms the non-emission hole region 10 b covers the bubble emission surface 8 b in a predetermined radius region from the rotation center of the bubble emitter 8. Microbubbles are not ejected from the side region, and coalescence of the microbubbles can be suppressed.

  Further, by rotating the bubble emitter 8 at a predetermined rotational speed, the surface flow velocity of the relative flow of water generated on the surface of the bubble discharge surface 8b outside the non-release hole region 10b is made a predetermined flow velocity. The coalescence of bubbles ejected from the bubble discharge surface 8b under the flow velocity is suppressed.

  Further, as described above, the blade 16 disturbs the flow of the relative flow on the surface of the bubble discharge surface 8b, and the turbulent flow with the vortex flow is surely generated on the surface of the bubble discharge surface 8b. It is possible to cause turbulent flow to act on the air ejected from the air and to promote the discrete and diffusion. Further, since the protruding body is formed of the coding layer, it is not necessary to form the protruding body integrally with the bubble emitting body or to be formed and attached as a separate member, and can be easily formed. In addition, the shape of the protrusion can be easily changed according to the application and use conditions. Furthermore, since the protrusion is formed by the coating layer, there is no problem that large bubbles are generated from the gap between the protrusion member and the bubble emitter, which is generated when a separate protrusion is attached.

  By the way, as shown in the frequency distribution of FIG. 6, the frequency of the bubbles of each bubble diameter contained in the air supplied from the fine bubble generator 1 to the water is the diameter ratio between the diameter D1 of the inner region and the diameter D2 of the outer region. The distribution varies depending on D1 / D2. The smaller the diameter ratio D1 / D2, that is, the smaller the inner region diameter D1, the wider the frequency distribution of the bubbles. The larger the diameter ratio D1 / D2, the greater the inner region diameter D1. The bubble frequency distribution is reduced to a narrow range.

Therefore, in the present embodiment, by setting the diameter ratio D1 / D2 = 0.7 or more, preferably 0.8 or more, the range of the bubble frequency distribution is narrowed to uniform the bubble diameter within a predetermined range a.
Further, in the present embodiment, the form of the protruding portion of the coating layer 10 formed on the surface of the bubble emitting surface 8b has been described as a blade form formed radially around the rotation axis of the bubble emitting body 8, It is not restricted to this form. For example, the protruding portions of the coating layer 10 may be formed as a plurality of convex bodies on the surface of the bubble discharge surface 8b. Further, it is possible to adopt a repeated pattern form in which a plurality of convex bodies are repeatedly formed at predetermined intervals. The shape of the convex body may be any shape such as a round shape and a square shape.

  Further, as shown in FIG. 9, the non-release hole region is not formed by the coating layer 10 but is formed by the doughnut-shaped bubble emitter 8 or covered by the plate-like body 20 as shown in FIG. You may form by. At this time, it is desirable that the gap between the bubble emitter 8 and the plate-like body 20 be hermetically sealed with an annular coating layer 21 or the like. By doing so, there is no possibility that the gas leaks from the gap between the bubble emitter 8 and the plate-like body 20 and coalesces.

Further, in the present embodiment, the configuration in which the bubble emitting surface 8b of the bubble emitting body 8 is a flat surface is shown, but as another embodiment of the present invention, the configuration shown in FIG. is there.
In FIG. 11, a main body casing 101 serving as an emitter holding means and a porous body 102 serving as a bubble emitter are formed in a cylindrical shape, and both of them are fixedly arranged concentrically. A water channel 103 is formed therebetween, and a gas chamber 104 is formed inside the porous body 102.

  In the porous body 102, a plurality of protrusions 106 projecting into water on the outer peripheral surface are formed in an annular shape around the axis of the porous body 102, and the protrusion 106 formed by the coating layer is the axis of the porous body 102. They are arranged at a predetermined pitch along the direction. The protruding body 106 can also be formed in a spiral shape. Moreover, you may form the protruding body 106 by a coating layer in an inner surface.

  In this configuration, a relative driving unit and a pump device that generate a relative flow on the bubble discharge surface 105 of the porous body 102 are employed. Water is supplied to the water channel 103 by the pump device, and air is supplied to the gas chamber 104 in a state where the water flows along the bubble discharge surface 105. The air in the gas chamber 104 is ejected as microbubbles through the bubble discharge hole of the porous body 102 onto the surface of the bubble discharge surface 105 that forms an interface with water, and flows on the surface of the bubble discharge surface 105 with a vortex. The relative flow entrains and separates microbubbles.

  The protrusion 106 of the porous body 102 disturbs the flow of the relative flow on the surface of the bubble discharge surface 105, and reliably generates a turbulent flow with a vortex on the surface of the bubble discharge surface 105, and is ejected from the bubble discharge hole. The turbulent flow is surely applied to the air.

  A low pressure region having a pressure lower than the surrounding average fluid pressure is formed on the bubble discharge surface 105 on the downstream side of the protrusion 106. The air ejected from the bubble discharge hole under this low pressure action becomes finer bubbles.

The front view which shows the microbubble generator in embodiment of this invention Sectional drawing which shows the bubble discharge | release part in the same embodiment (A) is a top view which shows the main body casing in the embodiment, (b) is AB sectional view taken on the line in (a). (A) is sectional drawing which shows the bubble emitter in the embodiment, (b) is a top view which shows the bubble emitter in the embodiment Sectional drawing which shows the bubble discharge body in the embodiment The chart which shows the frequency distribution of the bubble of each bubble diameter in the same execution form The front view which shows the microbubble generator in other embodiment The front view which shows the microbubble generator in other embodiment Sectional drawing which shows the microbubble generator in other embodiment Sectional drawing which shows the microbubble generator in other embodiment Sectional drawing which shows the microbubble generator in other embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fine bubble generator 2 Bottom wall surface 3 Leg part 4 Submersible motor device 5 Drive shaft 6 Bubble discharge part 7 Air supply pipe 8 Bubble discharger 8a Vent hole 8b Bubble discharge surface 9 Main body casing 9a Bonding hole 9b Keyway 10 Coating layer DESCRIPTION OF SYMBOLS 10a blade | wing part 10b no discharge | emission hole area | region 11 gas chamber 12 spacer 13 bolt 14 disc part 15 hub 15a connection hole 16 blade | wing 17 shaft sealing part 20 plate-like body 21 coating layer 101 main body casing 102 porous body 103 water channel 104 gas chamber 105 Bubble releasing surface 106

Claims (7)

A bubble emitter having a plurality of bubble emission holes on the bubble emission surface forming an interface with the liquid, an emitter holding means for holding the bubble emitter, a gas chamber communicating with the bubble emission hole, and supplying gas to the gas chamber Gas supply means for moving the bubble emitter relative to the liquid, and relative driving means for generating a relative flow of the liquid on the bubble discharge surface. An apparatus for generating fine bubbles, comprising a coating layer for preventing discharge, wherein the coating layer protrudes into a relative flow of liquid from the bubble discharge surface to form a protrusion having a predetermined shape on the bubble discharge surface. The relative drive means comprises a rotational drive device that rotationally drives the bubble emitter around the axis of the drive shaft, and a region within a predetermined radius from the center of rotation of the bubble emitter forms a non-discharge hole region that does not have a bubble discharge hole. The fine bubble generating apparatus according to claim 1. The surface flow velocity of the relative flow generated by the rotation of the bubble emitter on the bubble discharge surface outside the non-discharge hole region is a predetermined flow velocity that suppresses the coalescence of bubbles ejected from the bubble discharge surface. The fine bubble generator according to claim 2. In the bubble emitter, the non-discharge hole region occupies an inner region of a diameter D1 passing through the rotation axis of the bubble emitter, and the bubble discharge surface outside the non-release hole region has the rotation axis of the bubble emitter. 4. The fine bubble generating device according to claim 3, which occupies an outer region of the direct system D2 that passes through, and a diameter ratio D1 / D2 between the diameter D1 of the inner region and the diameter D2 of the outer region is 0.7 or more. The fine bubble generating device according to any one of claims 2 to 4, wherein the non-release hole region is formed of a coating layer that prevents release of bubbles formed on a bubble discharge surface. 6. The protruding portion formed on the bubble discharge surface has a blade shape formed radially around the rotation axis of the bubble emitter or a form formed by a plurality of convex bodies. The fine bubble generator according to any one of the above. The microbubble generator according to any one of claims 1 to 6, wherein the bubble emitter is made of a carbon material, a ceramic porous body, or a sintered metal.

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