JP2010194425A - Air diffuser and bubble generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bubble generator which generates a large amount of fine bubbles whose radius is roughly 50 μm or shorter, preferably 30 μm or shorter, while substantially reducing power without adding a chemical agent such as a surfactant, and is easily manufactured, and to provide an air diffuser. <P>SOLUTION: The air diffuser 12 includes: a gas chamber 16; a gas inflow pipe 18 for making a gas flow into the gas chamber 16; and a diffusion part 24 for diffusing the gas which has flowed in from the gas chamber 16 into liquid outside and making it flow out as bubbles. The diffusion part 24 is configured by laminating at least two planar members 30 and 32 which have many diffusion holes 30a and 32a in the inside respectively and comprise materials of different modulus of longitudinal elasticity while communicating the diffusion holes 30a and 32a with each other. The hole diameter of the diffusion holes 30a provided on one planar member 30 comprising the material of the larger modulus of longitudinal elasticity is larger than the hole diameter of the diffusion holes 32a provided on the other planar member 32 comprising the material of the smaller modulus of longitudinal elasticity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a bubble generating device that disperses a gas such as air into a large number of fine bubbles in a liquid such as water, and an air diffuser used in the bubble generating device. The bubble generating apparatus of the present invention is used in, for example, a sewage treatment tank, a river, a lake, aquaculture tank, etc., thereby improving the water quality by increasing the amount of dissolved oxygen in water, thereby facilitating the propagation of various useful organisms. Or a liquid in which a useful gas is dissolved, and fine bubbles are attached to the suspended matter mixed in the liquid to float and separate the suspended matter.

  As a bubble generating device for generating fine bubbles in a liquid, for example, a liquid is supplied to a gas dissolving device by a pump and pressurized, and a porous member provided in a discharge nozzle after mixing and dissolving the gas in the liquid In addition, there is known a technique in which fine bubbles are generated by rapidly depressurizing a liquid using a perforated plate (see Patent Document 1). This is a method capable of generating a large amount of very fine bubbles. However, in order to make the liquid mixed with gas high pressure, very large power is required.

  Also, a liquid is supplied to the bubble generating device by a pump to create a high-speed swirling flow in the casing of the bubble generating device, gas is introduced into the liquid swirling flow, and the gas is sheared at the center of the swirling flow. Also proposed is one that generates fine bubbles (see Patent Document 2). This is a technique in which, in order to obtain a liquid in which fine bubbles are mixed, the gas is sheared by the swirling flow of the liquid to make the bubbles fine. According to this method, a liquid in which fine bubbles are mixed can be obtained directly. However, the amount of fine bubbles generated is less than that of the above-described method in which gas is mixed in a liquid and dissolved, and then rapidly decompressed to generate bubbles. Moreover, in order to generate a high-speed swirling flow in the liquid, the liquid is considerably pressurized, so that a large amount of power is required.

  There is also proposed a bubble generating device in which a projection is provided in a liquid conduit, a bubble mixed liquid is collided with the projection, and the bubble is sheared by a shear flow generated at that time to generate fine bubbles. (See Patent Document 3). This method can also directly obtain a liquid in which fine bubbles are mixed. However, the amount of fine bubbles generated is less than that of the above-described method in which gas is mixed in a liquid and dissolved, and then rapidly decompressed to generate bubbles. Further, since a large loss occurs when the liquid mixed with bubbles collides with the protrusions in the water channel, it is necessary to pressurize the liquid considerably, and a large amount of power is required.

  Also, as a bubble generating device for generating fine bubbles in a liquid, a porous diffuser plate that is hollow and has fine diffuser holes on at least one surface, an diffuser plate with fine diffuser holes, or a fine diffuser plate is provided. Equipped with an air diffuser (air diffuser) with a diffused membrane with open pores, and this air diffuser can be placed immersed in the liquid in the air diffuser (treatment tank), or a liquid conduit So that the gas introduced into the air diffuser is diffused as bubbles from the fine air holes into the flowing liquid. This is generally known (see Patent Document 4, Patent Document 5 and Patent Document 6). These are methods for generating fine bubbles by shearing the gas discharged from the air holes by the buoyancy of the bubbles and the flow of the liquid. In these methods, since there is not much structure that causes a large loss in the flow path through which the liquid passes, it is not necessary to increase the pressure of the liquid compared to other methods, and bubbles can be generated with less energy than other methods. it can.

  However, among the above methods, in the method of generating fine bubbles by shearing the gas discharged from the porous diffuser plate with a liquid flow, the bubbles are combined when the gas is discharged from the porous diffuser plate. Therefore, it will become a big bubble as it is. Therefore, in this case, it is very difficult to generate fine bubbles unless a treatment such as adding a surfactant to the liquid is performed.

  On the other hand, instead of the porous diffuser plate, in order to generate very fine bubbles by a method of discharging gas from the diffuser plate with a large number of diffuser holes or diffuser membrane, It is necessary to make the hole diameter of the very small. When a diffuser plate having a large number of diffused holes having a very small hole diameter is used, it is not easy to process a very large number of fine diffused holes, and clogging of the diffused holes becomes a problem.

  In view of this, many methods have been adopted in which gas is diffused into the liquid from the holes (diffusive holes) of the diffuser film made of a resin film in which holes that become diffuse holes are formed by a needle or the like. That is, by using a resin film that has a certain elasticity and is easy to process compared to a metal plate or the like, a number of holes can be easily formed by opening holes (aeration holes) with a needle or the like. In addition, the hole diameter when the pressure is not applied to the gas can be reduced to substantially close the hole. Therefore, the hole (air diffused hole) opens only when the necessary pressure is applied to the gas, and the hole is closed when the gas pressure is lowered to stop the air diffused, so the hole (air diffused hole) is clogged. The occurrence of is reduced. For this reason, a method of forming a diffused film by opening a hole to be a diffused hole with a needle or the like in a resin film is widely adopted. However, the conventional bubble generator using a diffuser membrane cannot sufficiently reduce the diameter of the generated bubbles.

JP 2003-265938 A JP 2003-181258 A Japanese Patent Laid-Open No. 9-150044 JP 2000-205200 A JP-A-8-230762 JP-A-8-2225094

  Microbubbles are used to purify water by dissolving air in water, for example, in sewage treatment tanks, river water, lake water purification tanks, aquaculture tanks, etc. It is used for attaching fine bubbles to float and separate suspended matter, but the fine bubbles used in this case have an effective diameter of 100 μm or less, preferably 50 to 60 μm or less. It is.

  In order to suitably obtain the desired effect of the fine bubbles, it can be said that it is sufficient if a technique capable of suppressing the maximum value of the fine bubble diameter to a certain limit or less can be developed. That is, it is not necessary to bother to develop a technique for setting the lower limit of the diameter of the fine bubbles to a certain size or more. This is because, in a bubble generator with a relatively small power and a simple configuration, large-sized bubbles are easy to manufacture, but small-sized bubbles are generally difficult to manufacture, and the small-sized bubbles are naturally gathered to form a large-diameter. This is because a large-sized bubble does not naturally become a small-sized bubble. That is, if a small-sized bubble can be manufactured, it is easy to manufacture a larger bubble.

  After the liquid containing gas is pressurized to dissolve the gas in the liquid, the liquid is abruptly decompressed by the porous member or perforated plate provided in the discharge nozzle, and fine bubbles are generated. , A method of introducing a gas into the liquid swirl flow and shearing the gas at the center of the swirl flow to generate fine bubbles; Any method of generating fine bubbles by shearing bubbles by a flow requires large power. Further, in the method in which gas is discharged from the porous diffuser plate and fine bubbles are generated by the flow of liquid, the bubbles are combined to form large bubbles.

  On the other hand, the method of generating fine bubbles by discharging gas from holes (aeration holes) such as a diffuser plate or a diffuser membrane that has been subjected to fine hole processing and shearing the gas by the flow of liquid In comparison, less power is required to generate bubbles. However, when bubbles are generated from the fine air diffusion holes, in order to reduce the generated air bubbles, it is necessary to process the hole diameter of the air diffusion holes sufficiently small.

  In a conventional bubble generator using a diffuser membrane, there is little power required to generate bubbles, and when bubbles are not generated, the holes that generate bubbles (diffuse holes) are almost blocked, and clogging is difficult to occur. Since the hole can be opened with a thin needle or the like, there is an advantage that it is easy to manufacture a diffuser membrane.

  However, if the diameter of the hole that becomes the diffuser hole is made small in order to reduce the generated bubbles, the pressure loss during gas discharge becomes large, and it is necessary to increase the discharge pressure on the gas side. It will increase. Furthermore, in order to generate bubbles, simply increasing the pressure of the gas greatly expands the diffuser film made of a resin film or the like, and the holes (air diffuser holes) are larger than the desired size. Also grows. For this reason, it is extremely difficult to set the radius of the generated bubbles to, for example, 50 μm or less (diameter of 100 μm or less), and as a result, a sufficient amount of bubbles having the desired size cannot be generated.

  The present invention has been made in view of the above circumstances, and can generate a large amount of fine bubbles having a radius of about 50 μm or less, preferably 30 μm or less without adding a chemical such as a surfactant. An object of the present invention is to provide a bubble generating device that can greatly reduce the bubble generation power and can be easily manufactured compared to a conventional bubble generating device that generates bubbles of a certain size, and an air diffuser used for the bubble generating device. And

  As a result of intensive studies to solve the above-mentioned problems, the inventor is formed of a material that is relatively difficult to deform, such as metal, in other words, a material having a large longitudinal elastic modulus, and has a large number of air holes inside. A diffuser plate and a diffuser film formed of a material having a small longitudinal elastic modulus that is relatively elastically deformable, such as resin, and having a large number of diffuser holes therein are provided and provided on the diffuser film. The hole diameter of the air diffuser is set smaller than the hole diameter of the air diffuser plate, and the air diffuser plate and the air diffuser film are placed within the region of the air diffuser hole formed in the air diffuser plate. Preferably, the center of these diffused holes coincides with each other, for example, by combining them by bonding or the like to form a diffused portion to form a bubble, so that the radius is approximately 50 μm or less. It is preferable to generate a large amount of fine bubbles of preferably 30 μm or less. I thought that I could do it.

  That is, it is made of a material having a large longitudinal elastic modulus, such as metal or ceramics, and is made of a diffuser plate having a large number of through holes inside, and a material having a small longitudinal elastic modulus, such as resin or rubber, for example. The diffuser film having the pores is bonded by using, for example, an adhesive or the like while the positions of the diffuser pores are made to coincide with each other. As a result, the size (area) of the diffuser film that deforms under the pressure of the gas becomes substantially equal to the size (area) of the diffuser plate of the diffuser plate, and the diffuser part is formed only by the diffuser film, for example. Compared to the conventional example, the size of the diffuser holes of the diffuser film that deforms under the pressure of the gas is extremely small. Therefore, the amount of deformation (ie, expansion) of the air diffuser of the air diffuser can be suppressed to a small value, and the size of the air diffuser can be kept small, so that fine bubbles are generated by the gas flowing out from the air diffuser. It is possible. By setting the number of the air holes to an appropriate value, a large amount of fine bubbles can be generated.

  The invention described in claim 1 includes a gas chamber, a gas inflow pipe for allowing gas to flow into the gas chamber, and an air diffuser for diffusing and flowing out the inflowed gas as bubbles from the gas chamber into an external liquid. The air diffuser has at least two plate-like members made of materials each having a large number of air diffuser holes and having different longitudinal elastic modulus while communicating with each other. The diffused holes provided in the other plate-shaped member made of a material having a small longitudinal elastic modulus are formed by laminating and the hole diameter of the diffused holes provided in the one plate-shaped member made of a material having a large longitudinal elastic modulus It is an air diffuser characterized by being larger than the pore diameter.

  A steel plate such as a stainless steel plate is preferably used as the material having a large longitudinal elastic modulus, and a resin film such as a polyurethane resin film is preferably used as a material having a smaller longitudinal elastic modulus than the steel plate. Hereinafter, a plate-like member made of a material having a large longitudinal elastic modulus will be described as a steel plate-like member, and a plate-like member made of a material having a small longitudinal elastic modulus will be explained as a resin film-made plate-like member.

  By using a resin film such as a polyurethane resin film as a material having a small longitudinal elastic modulus, a gas flow for generating fine bubbles having a sufficiently small diameter is allowed to pass inside the plate member made of resin film. The holes used as the pores can be easily formed using a needle, for example. In addition, since the holes (air diffusion holes) are naturally closed when the gas flow is stopped, it is difficult for foreign matters to adhere to the openings, and there is an effect of preventing clogging. For example, an adhesive is used while connecting the resin film plate-like member to the steel plate plate-like member having a larger diameter of the air diffuser holes formed in the resin film plate-like member and communicating the two air diffuser holes to each other. A diffused part is formed by laminating and pasting the two plate members together.

  For example, when a gas pressure is applied to a plate-like member having a different longitudinal elastic modulus, a plate-like member made of a material having a smaller longitudinal elastic modulus is applied to the plate-like member made of a material having a larger longitudinal elastic modulus. It is easier to deform than members. However, if configured as described above, the resin film-made plate-like member alone is limited to the inside of the air holes formed in the steel plate-like plate member (that is, inside the air holes). Compared with a diffuser made only of a resin film plate member, for example, which is not provided with a plate member, the absolute amount of displacement of the resin film plate member is kept small and formed on the resin film plate member. The amount of change (increase) in the diameter of the holes (aeration holes) can also be suppressed to a small value. Moreover, since the longitudinal elastic modulus of a steel plate is large, the hole diameter of the diffused hole provided in the steel plate-like member remains very small even when a gas pressure is applied. Therefore, even when gas pressure is applied to the diffuser for diffusion, the size of the holes (diffuse holes) in the resin film plate-like member maintains the fine state necessary for generating fine bubbles. As a result, fine bubbles can be generated.

  In the invention according to claim 2, the one plate-like member is made of a material having a longitudinal elastic modulus of 50 GPa or more, the other plate-like member is made of a resin film, and the thickness of the one plate-like member is The air diffuser according to claim 1, wherein the air diffuser is thicker than the other plate-like member.

  A plate-like member made of a material having a large longitudinal elastic modulus is a diffuser formed on a plate-like member made of a material having a small longitudinal elastic modulus by reducing the amount of deformation of the diffuser due to the pressure of the gas applied inside. Used to suppress changes in pore diameter. On the other hand, a plate-like member made of a material having a small longitudinal elastic modulus allows gas to pass through a hole (aeration hole) formed in the diffusion member, and the hole is blocked when the gas flow is stopped. Since it is desirable, it is preferable that the shape restoring property is large as a characteristic of the material itself. That is, when the gas pressure in the gas chamber inside the diffuser rises to generate bubbles, the hole diameter of the diffuser holes needs to open to an appropriate size, and the gas pressure is set to stop the bubble generation. It is preferred that the air diffuser closes when lowered. Therefore, the thickness of the plate member made of a material having a large longitudinal elastic modulus is thicker than the thickness of the plate member made of a material having a small longitudinal elastic modulus, and the material of the plate member made of a material having a small longitudinal elastic modulus is resin. It is preferable.

  In addition, if the longitudinal elastic modulus of the plate-like member made of a material having a large longitudinal elastic modulus is 50 GPa or more, the amount of change in the diameter of the air diffusion hole of the plate-like member made of a material having a small longitudinal elastic modulus can be suppressed. As a result, the air diffuser is configured using only a resin film, for example, and the hole diameter of the air diffuser in the resin film is suppressed to a small value compared to the case where a plate-like member having a large longitudinal elastic modulus is not used. be able to.

  The invention according to claim 3 is characterized in that the one plate-like member is arranged on the gas chamber side, and the other plate-like member is arranged on the side in contact with the external liquid. 2. The air diffuser according to 2.

  When the gas flows out from the diffuser holes formed in the diffuser part of the diffuser into the flowing liquid outside the diffuser, the gas receives a drag force from the flowing liquid as bubbles, and the gas is diffused by this drag. Detaches from and becomes a bubble. Since the drag increases as the velocity of the flowing liquid increases, in order to generate fine bubbles, it is desirable that the flow velocity of the flowing liquid on the flowing liquid side surface of the diffuser is large. If a plate-shaped member made of a material having a large longitudinal elastic modulus is disposed on the fluid liquid side, the depth of the air diffusion holes formed in the plate-shaped member is equal to the thickness of the plate-shaped member. The flow velocity of the flowing liquid in the vicinity of the surface of the plate member made of a material having a small elastic modulus becomes smaller due to the influence of the thickness of the plate member made of a material having a large longitudinal elastic modulus, and the generated bubble diameter becomes larger. End up. Therefore, it is preferable to dispose a plate-like member made of a material having a small longitudinal elastic modulus, for example, a resin film-made plate-like member on the flowing liquid side.

  In the invention according to claim 4, the hole diameter of the air diffuser provided in the one plate-like member is 0.5 to 2 mm, and the hole diameter of the air diffuser provided in the other plate-like member is 30 μm or less. It is a diffuser as described in any one of Claims 1 thru | or 3 characterized by the above-mentioned.

  The diameter of the air diffuser provided in the plate-like member made of a material having a large longitudinal elastic modulus is generally 0.5 to 2 mm, and preferably 0.5 to 1 mm. Moreover, the hole diameter of the diffused holes provided in the plate-like member made of a material having a small longitudinal elastic modulus is generally 30 μm or less and preferably 20 μm or less.

  A fifth aspect of the present invention includes a plurality of the air diffusion devices according to any one of the first to third aspects, wherein the air diffusion portions of the air diffusion devices are parallel to each other and the air diffusion devices are disposed in the liquid passage. It is the bubble generator characterized by having installed in.

  The air diffuser of the air diffuser is separated by the air diffuser by configuring the air diffuser as a mode in which a plate-like member having a large longitudinal elastic modulus and a plate-like member having a low longitudinal elastic modulus are bonded to each other. Even if the pressure difference between the gas side and the liquid side increases, the amount of deflection in the direction perpendicular to the diffuser surface of the diffuser can be maintained at a small value. Therefore, an air diffuser comprising a gas chamber, a gas inflow pipe that allows gas to flow into the gas chamber, and an air diffuser that diffuses the inflowed gas as fine bubbles from the gas chamber into an external flowing liquid. A plate-like member in which a large number of holes having a relatively large longitudinal elastic modulus and a relatively large hole diameter are formed as described above; If the air diffuser is an air diffuser configured as an embodiment in which a plate-like member having a large number of holes having a small hole diameter is fixed to each other, for example, a plurality of air diffusers are provided. If the bubble generating device is configured by preparing them and arranging them in the liquid passage so that the air diffusers are parallel to each other, there is no fear that one air diffuser will come into contact with another air diffuser. Accordingly, it is possible to install a plurality of the air diffusers in the liquid passage with a small interval between them, and it is possible to provide a large number of bubble generation holes in a narrow liquid passage space. A large amount of fine bubbles can be generated in the apparatus.

  The invention according to claim 6 is the air diffuser according to any one of claims 1 to 3, which is disposed so as to be immersed in the liquid in the air diffuser, and the surface of the air diffuser of the air diffuser. And a liquid flow forming device for forming a flow of liquid in the air diffusion tank along the air bubble generating device.

  The liquid flow forming device is configured to include, for example, a pump, a liquid pipe and a nozzle, and for example, the liquid in the air diffusing tank is discharged from the nozzle to form a liquid flow in the air diffusing tank. The air diffuser and the nozzle are arranged in the air diffuser so as to flow along the surface of the air diffuser (air diffuser surface) of the air diffuser provided in the air diffuser. With this configuration, when the gas flows out from the diffuser holes formed in the diffuser part into the liquid flow along the surface of the diffuser part, the gas discharged from the diffuser hole receives a drag force from the liquid flow. Thus, the fine bubbles can be generated because the bubbles are separated from the diffuser holes while the bubble diameter is small. At this time, it is preferable that the flow velocity of the liquid flow in the vicinity of the diffuser along the diffuser surface is about 3 m / s to 5 m / s. Further, for example, if the liquid flow formed by the liquid flow forming device is configured to circulate in the air diffusion tank, the amount of gas dissolved in the liquid can be increased.

  Advantageous Effects of Invention According to the present invention, it is possible to provide a bubble generating device that generates a large amount of fine bubbles with low power, has a small amount of clogging of the diffusion holes, is compact and easy to manufacture, and an aeration device used for the bubble generating device. .

It is a schematic diagram of a bubble generating device of an embodiment of the present invention. It is a cross-sectional top view of the diffuser with which the bubble generator shown in FIG. 1 is equipped. It is a schematic diagram of the bubble generator of other embodiment of this invention. It is a cross-sectional top view which shows the bubble generator of further another embodiment of this invention. It is a figure attached to description of the principle of bubble generation. It is a figure attached | subjected to description of a deformation | transformation of a diffuser film when a uniformly distributed load acts on the diffuser film simply supported by the outer peripheral end perpendicularly to the surface. It is sectional drawing of the diffuser film shown in FIG. It is a figure attached | subjected to description of a deformation | transformation of a diffuser plate when a uniformly distributed load acts on the diffuser plate fixedly supported by the outer peripheral end perpendicularly to the surface. It is sectional drawing of the diffuser plate shown in FIG. It is a figure attached | subjected to description of a deformation | transformation of this steel plate plate-shaped member and resin film plate-shaped member at the time of laminating | stacking a steel plate plate-shaped member and a resin film plate-shaped member, (a) is a top view, (b ) Is a cross-sectional view.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following examples, the same or corresponding members are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic diagram of a bubble generating device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional plan view of an air diffuser provided in the bubble generating device shown in FIG. As shown in FIG. 1, the bubble generating device is immersed in a liquid flowing inside a liquid passage (liquid conduit) 10, and a plurality of (two in the drawing) arranged in parallel with each other along the flow direction of the liquid. A diffuser 12). Each air diffuser 12 is connected to a diffuser body 14 having a substantially wing-shaped cross section and a blower (not shown), and gas is supplied to a gas chamber 16 (see FIG. 2) provided inside the diffuser body 14. And a gas inflow pipe 18 through which gas flows in.

  The diffuser body 14 has a box shape with rectangular openings 20 on both side surfaces, and has a substantially wing-shaped outer shell 22, and the diffuser 24 is attached to each opening 20. Thus, as shown in FIG. 2, a gas chamber 16 communicating with the lower end of the gas inflow pipe 18 is formed inside. As shown in FIG. 1, the air diffuser 12 is disposed inside the liquid passage 10 so that the air diffusers 24 of the air diffuser 12 are parallel to each other.

As shown in FIG. 2, each air diffuser 24 includes two plate-like members made of materials having different longitudinal elastic modulus, and in this example, stainless steel having a longitudinal elastic modulus of about 2 × 10 ¹¹ (Pa) (200 GPa). A plate-like member made of a steel plate (hereinafter referred to as a steel plate-like plate-like member) 30 and a plate-like member made of a polyurethane resin film having a longitudinal elastic modulus of about 3 × 10 ⁹ (Pa) (3 GPa) (hereinafter referred to as a resin film-made plate) (Referred to as a member) 32 are laminated by bonding or the like.

  A large number of air diffusion holes 30 a are provided inside the steel plate plate member 30, and a large number of air diffusion holes 32 a are also provided inside the resin film plate member 32. The hole diameter of the air diffuser hole 30 a of the steel plate plate member 30 is set larger than the hole diameter of the air diffuser hole 32 a of the resin film plate member 32. The hole diameter of the air diffuser 30a of the steel plate plate member 30 is generally 0.5 to 2 mm, preferably 0.5 to 1 mm, for example 1 mm. The hole diameter of the air diffusion holes 32a of the resin film plate member 32 is generally 30 μm or less, preferably 20 μm or less, for example, 10 μm.

  In the case where gas is discharged from a fine air diffuser into a liquid flow to generate bubbles having a radius of 50 μm or less, if the flow rate of the liquid is, for example, about several m / s, the diameter of the air diffuser must be about 10 μm. There is. However, assuming that the thickness of the steel plate member 30 is about 1 mm, it is difficult to manufacture such fine holes in the steel plate member 30. On the other hand, in the resin film-made plate-like member 32, for example, a hole having a hole diameter of about 10 μm is used as an air diffusion hole through which a gas flow for generating fine bubbles having a sufficiently small diameter is passed. For example, it can be easily formed using a needle. In addition, this hole (aeration hole) is naturally closed because the pressure of the gas in the gas chamber is reduced when the gas flow is stopped, so that there is an effect of preventing clogging and the like.

  Then, the steel plate plate member 30 and the resin film plate member 32 are positioned on the outside where the resin film plate member 32 is in contact with the liquid while the diffuser holes 30a and 32a are in communication with each other. The air diffuser 24 is configured by pasting and laminating each other with an adhesive 34. The thickness of the steel plate plate member 30 is, for example, 1 mm, and the thickness of the resin film plate member 32 is, for example, 0.5 mm.

  The air diffuser 24 is located between the peripheral edge of the air diffuser 24 and a portion located around the opening 20 of the outer shell 22 at a position that closes the opening 20 of the outer shell 22. A rectangular frame-shaped sheet packing 36 that prevents gas from leaking from the gap between the outer shell 22 and the outer shell 22 is attached. The gas chamber 16 and the steel plate plate member 30 may be integrated to prevent the gas from leaking out.

  The steel plate member 30 and the resin film plate member 32 are laminated so that the center of the air hole 30a of the steel plate member 30 and the center of the air hole 32a of the resin film plate member 32 coincide with each other. However, it is not always necessary to match. For example, the air holes 30a of the steel plate member 30 may be processed at twice the pitch between the air holes 32a of the resin film plate member 32 processed in large numbers, or the resin film plate member The 32 air diffuser holes 32a may be accommodated in the air diffuser holes 30a of the steel plate member 30 (that is, within the range in which the air diffuser holes 30a of the steel plate member 30 are formed).

  Further, the air diffuser holes 30a of the steel plate plate member 30 and the air diffuser holes 32a of the resin film plate member 32 do not necessarily correspond one-to-one. Then, a plurality of air diffusion holes 32 a may be formed in the resin film plate-like member 32.

  Further, although not shown in the figure, air diffused holes are formed in each of three or more plate-like members including two plate-like members having different longitudinal elastic coefficients, and these diffused holes are connected to each other and fixed to each other by bonding or the like. Then, the diffuser portion may be formed by stacking.

  As described above, when the air diffuser 24 is configured by laminating the steel plate plate member 30 and the resin plate plate member 32, the resin film plate member 32 is present alone. 30 is limited to the inside of the air diffuser hole 30a formed in the air hole 30a (that is, the inner side of the air diffuser hole 30a). In comparison, the absolute amount of displacement of the resin film-made plate-like member 32 can be kept small, and the change amount (increase amount) of the air hole 32a formed in the resin film-made plate-like member 32 can be kept small. it can. Moreover, since the longitudinal elastic modulus of the steel plate is large, the hole diameter of the diffused holes 30a provided in the steel plate-like plate member 30 remains extremely small even when a gas pressure is applied. Therefore, even when a gas pressure is applied to the diffuser 24 to diffuse, the size of the diffuser holes 32a of the resin film-made plate-like member 32 maintains a fine state necessary for generating fine bubbles. As a result, fine bubbles can be generated.

  In this example, a stainless steel plate is used as a material having a large longitudinal elastic modulus. However, other steel plates or the like having a longitudinal elastic modulus of 50 GPa or more may be used. Any resin film other than the polyurethane resin film may be used. In addition, the thickness of the plate-like member made of a material having a large longitudinal elastic modulus such as the steel plate-like plate member 30 is thicker than the thickness of the plate-like member made of a material having a small longitudinal elastic modulus such as the resin film plate-like member 32. Is preferred.

  According to this bubble generating device, a gas such as air is supplied into the gas chamber 16 in the diffuser tank main body 14 through the gas inflow pipe 18 by, for example, a blower. Then, the gas introduced into the gas chamber 16 sequentially passes through the air holes 30a of the plate member 30 made of steel plate and the air holes 32a of the plate member 32 made of resin film, and then the liquid force flowing through the liquid passage 10 is increased. The air bubbles are diffused into the liquid flowing along the liquid passage 10.

  As in this example, if a plurality of air diffusers 10 are prepared and the air diffuser 10 is installed in the liquid passage 10 so that the air diffusers 24 are parallel to each other, the air bubble generator is configured. Even if the pressure in the gas chamber increases due to the gas used, the amount of deformation of the air diffuser is small and virtually negligible. Therefore, there is no possibility that one air diffuser will come into contact with another air diffuser. Accordingly, it is possible to install a plurality of air diffusers 12 in the liquid passage 10 with a small interval between them, and it is possible to provide a large number of bubble generation holes in a narrow liquid passage space. A large amount of fine bubbles can be generated by the generator.

  Further, by arranging the surface of the air diffuser 24 of the air diffuser 12 in the liquid passage 10 so as to be almost parallel to each other, the flow state of the liquid along the surface of the air diffuser 24 is made substantially constant. Therefore, the bubble diameter distribution is difficult to spread, bubbles having a substantially constant bubble diameter can be generated in the liquid, and generation of large bubbles can be suppressed.

  FIG. 3 shows a bubble generator according to another embodiment of the present invention. The bubble generating device of this example includes an air diffuser 12 disposed so as to be immersed in the liquid diffuser tank 40 in which a liquid (treatment liquid) is stored. The air diffuser 12 is installed vertically so that the surface of the air diffuser 24 (see FIG. 2) extends along the vertical plane, and the gas chamber 16 inside the air diffuser 12 is disposed at the upper end of the air diffuser 12. A gas inflow pipe 18 for allowing gas to flow into is connected.

  The bubble generating device has a pump 42, a liquid pipe 44 and a nozzle 46, and forms a fluid flow in the air diffusing tank 40 along the surface of the air diffusing portion of the air diffusing device 12 as the pump 42 is driven. The liquid flow forming device 48 is provided. In this example, the nozzle 46 is positioned slightly above the air diffuser 12 and is arranged downward in the vertical direction. As the pump 42 is driven, the liquid along the air diffuser surface of the air diffuser 12 is discharged. A downward flow is formed.

  According to this example, the pump 42 is driven to form a downward flow of the liquid along the surface of the air diffuser of the air diffuser 12. A gas such as air is supplied to the inside of the gas chamber 16 in 14. Then, the gas introduced into the gas chamber 16 sequentially passes through the air diffuser holes 30a of the steel plate plate member 30 and the air diffuser holes 32a of the resin film plate member 32 in the same manner as described above, and then the air diffuser 12. In response to the drag of the liquid flowing along the surface of the air diffuser, air bubbles are diffused into the liquid in the air diffuser 40. Thus, since the gas discharged from the air diffuser receives drag from the liquid flow and is released from the air diffuser while the bubble diameter is small, fine bubbles can be generated.

  The flow rate of the liquid flow in the vicinity of the air diffuser 24 along the surface of the air diffuser 24 is preferably about 3 m / s to 5 m / s. In addition, for example, by configuring the liquid flow formed by the liquid flow forming device 48 to circulate in the air diffusion tank 40, the amount of gas dissolved in the liquid in the air diffusion tank 40 can be increased. .

  FIG. 4 shows a bubble generator according to still another embodiment of the present invention. The bubble generating apparatus of this example includes an air diffuser 12 shown in FIG. 2 and two other air diffusers 12a and 12a obtained by dividing the air diffuser 12 shown in FIG. 12, 12 a and 12 a are arranged in parallel with each other along the flow direction of the liquid flowing along the fluid passage 10 inside the liquid passage (liquid pipe) 10.

  Each air diffuser 12a has a diffuser body 14a having an outer shell 22a having a half-wing cross-sectional shape and an opening 20a, and the air diffuser 24 is attached to the opening 20a. Yes. Then, the halved surface of the outer shell 22a is brought into close contact with the wall surface of the liquid passage 10 and the air diffuser 12a is installed in the fluid passage 10 so that the space between the outer shell 22a and the wall surface of the liquid passage 10 is measured. A gas chamber 16a communicating with a gas inflow pipe 18 (see FIG. 2) extending from the outside is formed.

  According to this example, it is possible to effectively dispose a diffuser device in a narrow fluid passage and to provide a large amount of bubble generating holes, so a large amount of fine bubbles can be generated with a compact bubble generating device. Can be generated.

  Next, in the air diffuser configured as described above, air diffuser holes provided in a plate member made of a material having a small longitudinal elastic coefficient, such as air diffuser holes 32a provided in the resin film plate member 32, etc. The amount of radial deformation and the amount of deflection of the hole diameter will be described.

  First, as shown in FIG. 5, the gas and the liquid flowing in the flow path are partitioned by a plate 52 having a diffused hole 50 which is a fine circular hole. Consider the state of flowing out as 54. Here, when a gas is injected into the liquid flow path from the fine circular air diffuser hole 50 and the gas flows out from the air diffuser hole 50 to the liquid side, the gas is sheared with the liquid to generate fine bubbles 54. In this case, when the force that causes the bubbles 54 to leave the diffuser holes 50 becomes larger than the force that the bubbles 54 try to stay at the positions of the diffuser holes 50, the bubbles 54 are detached from the diffuser holes 50.

The force with which the bubbles 54 stay at the position of the diffuser holes 50 is equal to the surface tension acting on the portion where the bubbles 54 and the diffuser holes 50 are in contact, that is, the gas-liquid interface. Assuming that the surface tension coefficient at the gas-liquid interface is σ (N / m) and the hole radius of the air diffusion hole 50 is b (m), the surface tension F (N) acting on the bubble 54 is expressed by the following equation (1).

  The force for separating the bubbles 54 from the diffuser holes 50 is received from the flowing liquid. Considering that it is obvious that the smaller the hole diameter of the bubbles 54, the smaller the force that the bubbles 54 receive from the liquid. From the equation (1), in order to reduce the bubble diameter of the bubbles 54 generated from the fine air diffusion holes 50, Indicates that the hole diameter of the air diffusion holes 50 needs to be reduced. For example, in order to set the flow velocity of the liquid flowing in the normal liquid passage (liquid conduit) to about several m / s and the bubble radius of the generated bubbles to be 50 μm or less, the radius of the air diffuser is set to be several μm or less. There is a need to.

Then, the differential pressure between the inlet outlet of diffusing pores 50 necessary for the diffusing pores 50 for generating the bubble 54 is gas passes, the pressure loss due to friction when the gas passes through the hole diffuser 50 P _h in, indicating the amount of the pressure loss P _h below. Here, the radius of the diffuser hole 50 for generating the bubble 54 is b (m), the length of the diffuser hole 50 is the same as the thickness of the plate 52, h (m), and the flow velocity of the gas passing through the diffuser hole 50 is determined. V (m / s), the density of gas is ρ (kg / m ³ ), the friction coefficient of the circular tube forming the gas passage is λ, the kinematic viscosity of the gas is η (m ² / s), and the diffuser holes 50 are assuming that the Reynolds number of the gas passing through the diffusing pores 50 smaller is smaller laminar flow pressure loss P _h due to friction when passing through the pores 50 gas dispersion becomes equation (2).

Therefore, reducing the radius b of the diffusing pores 50, the pressure loss P _h when passing through the pores 50 gas dispersion is increased, the plate 52 which partitions between the gas and liquid, directed from the gas side to the liquid side the plate A pressure in a direction perpendicular to 52, that is, a uniform distributed load acts.

  Next, the amount of deformation in the radial direction of the air holes 30a provided in the steel plate plate member 30 and the air holes 32a provided in the resin film plate member 32 of the air diffuser 24 of the air diffuser 12 shown in FIG. The amount of bending of the steel plate plate member 30 and the resin film plate member 32 will be considered. At this time, a pressure equal to the pressure difference between the pressure on the gas side and the pressure on the liquid side existing across the air diffuser 24 is a uniform distributed load on the steel plate plate member 30 or the resin film plate member 32. It shall act. The radial deformation amount and the bending amount will be described below separately for the plate member 30 made of steel plate and the plate member 32 made of resin film.

  Now, for the sake of simplicity, a circular diffuser plate (corresponding to a steel plate plate member 30) or a diffuser film (corresponding to a resin film plate member 32) having one fine diffuser hole in the center, Consider a case where pressure in a direction perpendicular to the surface, that is, a uniform distributed load is applied. First, regarding the diffuser membrane, it is assumed that a commonly used resin film that is easily deformed with a diffuser hole formed by a needle or the like is assumed to be deformed at the outer peripheral end, and simple support that is freely deformed at the outer peripheral end is assumed. On the other hand, it is assumed that the diffuser plate cannot be deformed at the outer peripheral end and is fixed at the outer peripheral end. In addition, although the hole opened with the needle | hook etc. in the resin film which is generally used above which is easy to deform | transform is not necessarily a circular hole, it is considered here as a circular hole. Thereby, the operational effects achieved by the present invention can be easily understood.

First, as shown in FIG. 6, an evenly distributed load p (Pa) perpendicular to the surface is formed on a circular diffuser film 60 having a fine circular diffuser hole 60 a in the center and having a thickness h (m). Consider the deformation in the case of simple support at the outer peripheral edge. The outer radius of the circular diffuser membrane 60 is a (m), the inner radius of the fine diffuser hole 60a at the center is b (m), the longitudinal elastic modulus is E (N / m ² ), and the Poisson's ratio is ν ( When −), the deflection amount w (m) of the diffuser membrane 60 is expressed by equation (3), and the circumferential stress σ _θ (N / m ² ) is expressed by equation (4).

Since the circumferential stress σ _{θmax in the} vicinity of the opening of the fine diffuser hole 60a at the center can be regarded as _b≈0 with respect to the dimension a, if Equation (4) is modified to set the Poisson's ratio ν to 0.3. Equation (5) is obtained.

The radial stress in the vicinity of the opening of the air diffusion hole 60a is zero. In the vicinity of the opening of the fine diffuser hole 60a at the center, the deformation rate in the radial direction and the deformation rate in the circumferential direction are the same, the amount of deformation in the circumferential direction of the diffuser hole 60a and the circumferential stress of the diffuser hole 60a. Using the relational expression, the circumferential stress equation (5) in the vicinity of the hole obtained as a minute hole such that the central diffuser hole 60a can be regarded as b≈0 with respect to the dimension a is a basic expression of stress and deformation as follows. by substituting the second term of equation (6), the radial deformation of u _b of the opening of the aeration pores 60a can be obtained by equation (6).

Further, the maximum deflection amount w _max of the diffuser membrane 60 is obtained by modifying Equation (3) as a minute hole so that the central diffuser hole 60a can be regarded as b≈0 with respect to the dimension a, and the Poisson's ratio ν is set to 0.3. Then, Expression (7) is obtained.

Here, in order to clarify that the material is only the resin film, as shown in FIG. 7, each symbol is represented by adding a subscript film, and the outer peripheral radius of the resin film 60 is represented by a _{film, l} . If the radius of the diffuser hole 60a of the film 60 is b _film , the thickness of the resin film 60 is h _film , and the longitudinal elastic modulus of the resin film 60 is E _film , the radial direction of the radius b _film of the diffuser hole 60a of the resin film 60 The deformation amount _{ubfilm, film} is given by equation (8), and the maximum deflection amount w _{film, max} is given by equation (9).

On the other hand, as shown in FIG. 9, a distributed load p (Pa) acts on a circular diffuser plate 70 having a fine circular diffuser hole 70a in the center perpendicularly to the surface, and is fixedly supported at the outer peripheral end. In consideration of the deformation in the case, the deflection amount w (m) of the diffuser plate 70 is expressed by equation (10), and the circumferential stress σ _θ (N / m ² ) is expressed by equation (11).

Since the circumferential stress σ _{θmax in the} vicinity of the opening of the fine diffuser hole 70a at the center can be regarded as _b≈0 with respect to the dimension a, if Equation (11) is modified to set the Poisson's ratio ν to 0.3. Equation (12) is obtained.

The radial stress in the vicinity of the opening of the diffuser hole 70a is zero. In the vicinity of the opening of the fine air diffuser hole 70a in the center, the deformation rate in the radial direction and the deformation rate in the circumferential direction are the same, the amount of deformation in the circumferential direction of the air diffuser hole 70a and the circumferential stress of the air diffuser hole 70a. Using the relational expression, the expression (12) of the circumferential stress in the vicinity of the diffuser hole 70a obtained as a minute hole such that the central diffuser hole 70a can be regarded as b≈0 with respect to the dimension a is a basic expression of stress and deformation. by substituting the second term of the following formula (13), the radial deformation of u _b of diffusing pores 70a can be obtained by equation (13).

Further, the maximum deflection amount w _max of the diffuser plate 70 is modified so that the central diffuser hole 70a is a minute hole such that b≈0 with respect to the dimension a, and the Poisson's ratio ν is set to 0.3. If it becomes, it will become a formula (14).

Here, in order to clarify that the material is only a material such as a stainless steel plate, for example, as shown in FIG. Is a _sus , the radius of the diffuser hole 70 a of the diffuser plate 70 is b _sus , the thickness of the diffuser plate 70 is h _sus , and the longitudinal elastic modulus of the diffuser plate 70 is E _sus , the diffuser of the diffuser plate 70 The radial deformation amount u _{bsus, sus} of the radius b _sus of the pore 70a is expressed by the equation (15), and the maximum deflection amount w _{sus, max} is expressed by the equation (16).

  Therefore, the amount of deformation in the radial direction of the fine diffuser holes 60a and 70a at the center of the circular diffuser membrane 60 and the diffuser plate 70 is the distributed load p, the initial value regardless of whether the outer peripheral end is free support or fixed support. Is proportional to the square of the outer peripheral radius a of the circular diffuser membrane 60 and the diffuser plate 70, and is the square of the longitudinal elastic modulus E and the thickness h of the diffuser membrane 60 and diffuser plate 70. Inversely proportional to

  Further, the maximum amount of deflection of the circular diffuser membrane 60 and the diffuser plate 70 is the distributed load p, and the circular circular diffuser membrane 60 and diffuser, regardless of whether the outer peripheral end is free support or fixed support. It is proportional to the fourth power of the outer peripheral radius a of the plate 70 and inversely proportional to the third power of the longitudinal elastic modulus E and the thickness h of the circular diffuser film 60 and the diffuser plate 70.

Next, as the diffuser film 60 formed of a relatively easily deformable material, for example, a polyurethane resin film is used, and as the diffuser plate 70 formed of a relatively hardly deformable material, for example, a stainless steel plate is used. A diffused part having a diffused surface with a size of about several tens of cm ² is considered, and a circular part having a radius of several centimeters is assumed in the diffused part and compared below. First, the thickness of the diffuser film 60 made of polyurethane resin film and the diffuser plate 70 made of stainless steel plate are the same, and in the case of the diffuser plate 70, the diffuser holes 70a having the same diameter as the diffuser film 60 can be opened. Assuming that the hole diameter is the same (before deformation due to an evenly distributed load), comparison is made.

Regarding the deformation of the diffuser holes 60a and 70a, the expression (8) of the radial deformation of the diffuser hole 60a of the diffuser film 60 and the expression (15) of the radial deformation of the diffuser hole 70a of the diffuser plate 70 are compared. The longitudinal elastic modulus is about E _{sus ≈2} × 10 ¹¹ (Pa) (200 GPa) for the stainless steel plate and about E _film ≈3 × 10 ⁹ (Pa) (3 GPa) for the polyurethane resin film. If the support conditions at the outer peripheral end are the same, the amount of deformation in the radial direction of the diffuser hole 70a of the diffuser plate 70 made of stainless steel plate is different from that of the diffuser membrane 60 made of the polyurethane resin film due to the difference in the longitudinal elastic modulus E. than the radial deformation of the ^{60a 1/67 (= 3 × 10 9} /2 × 10 11) smaller in extent. Furthermore, since it is appropriate to consider the support condition of the outer peripheral end as a fixed support and a simple support for the diffuser plate 70 made of stainless steel plate and the diffuser film 60 made of a polyurethane resin film, respectively, Due to the difference in fixed support, the amount of deformation in the radial direction of the diffuser hole 70a of the diffuser plate 70 made of stainless steel plate is 1 / 2.5 of the amount of radial deformation of the diffuser membrane 60a of the diffuser membrane 60 made of polyurethane resin film. It becomes as small as (= 0.975 / 2.475).

  For this reason, due to the difference in the longitudinal elastic modulus and the support conditions, the amount of radial deformation of both diffuser holes varies greatly depending on the difference in both materials. From the synergistic product of the above 1/67 and 1/2. The amount of deformation in the radial direction of the air diffusion hole 70a of the air diffusion plate 70 is reduced to about 1/170 of the amount of deformation in the radial direction of the air diffusion hole 60a of the air diffusion film 60 made of a polyurethane resin film.

  Next, as shown in FIG. 2, the steel plate plate member 30 and the resin film plate member 32 are provided on the steel plate plate member 30 in the air diffuser 24 formed by being bonded with an adhesive 34 or the like. The amount of radial deformation of the diffuser holes 32a provided in the diffuser holes 30a and the resin film plate-like member 32 will be described with reference to FIG.

In this case, first, when a pressure is applied to the plate member 30 made of steel plate, the plate member 30 made of steel plate is bent, and the diffuser holes 30a of the plate member 30 made of steel plate are deformed in the radial direction. The amount of deformation in the radial direction of the _{air diffusion hole} 30a of the plate member 30 made of steel plate is defined as u _{bsus, sus} (S). A resin film plate having an outer peripheral diameter of 2b _sus (= 2a _{film, 2} ) _, which is the diameter of the air _diffuser hole 30a of the steel plate plate member 30, due to the deformation in the radial direction of the _{air diffuser} hole 30a of the steel plate member 30. The shaped member 32 is stretched in the radial direction. The amount of deformation in the radial direction of the _{air diffusion holes} 32a of the resin film plate-like member 32 caused by the deformation in the radial direction of the _{air diffusion holes} 30a of the steel plate-like plate member 30 is defined as _{ubfilm, sus + film, A} (A).

At the same time, a pressure is applied to the resin film plate member 32 having an outer diameter of 2b _sus (= 2a _{film, 2} ) _, which is the portion of the air _diffuser 30a of the steel plate plate member 30, whereby a resin film plate shape is formed. The member 32 is bent, and the air diffusion holes 32a of the resin film plate-like member 32 are extended in the radial direction. The amount of deformation in the radial direction of the _{air diffusion hole} 32a of the resin film-made plate-like member 32 caused by the pressure acting on the resin film-made plate-like member 32 is defined as _{ubfilm, sus + film, B} (B).

In the air diffuser 24 in which the resin film plate member 32 is bonded to the steel plate plate member 30 with an adhesive 34 or the like, the amount of radial deformation of the fine air diffuser holes 32a at the center of the resin film plate member 32 is reduced. Is the amount of deformation u _{bfilm, sus + film, A} (A) in the radial direction of the _{air diffusion holes} 32a of the resin film plate-like member 32 caused by the radial deformation of the _{air diffusion holes} 30a of the steel plate-like member 30 and the resin film The sum of the deformation amount u _{bfilm, sus + film, B} (B) in the radial direction of the _{air diffuser} 32a of the resin film plate-like member 32 generated due to the pressure acting on the plate-like member 32 u _{bfilm, sus + film} (A + B).

First, an expression relating to the amount of deformation u _{bfilm, sus + film, A} (A) in the radial direction of the _{air diffusion hole} 32a of the resin film plate-like member 32 caused by the deformation in the radial direction of the _{air diffusion hole} 30a of the steel plate-like plate member 30 is shown. .
The radius b _sus of the air diffuser 30a of the steel plate member 30 when the distributed load p is applied to the circular plate member 30 having the fine circular air diffuser 30a in the center and perpendicular to the surface. The directional deformation amount u _{bsus, sus} (S) is expressed by equation (15).

Next, in order to obtain the amount of deformation in the radial direction generated in the diffuser holes 32a of the resin film plate-like member 32, the outer diameter is 2a _{film, the} diameter of the central diffuser hole 32a is 2b _{film and} the cylindrical shape is low. A resin film plate-like member 32 is assumed. Here, uniform distribution load p ₂ in the radial direction acts on the outer periphery, the inner of the case where the load on the peripheral does not act, the radial deformation of the radius r of the resin film made plate member 32 of the cylindrical u _{film, A} is represented by Expression (17).

Therefore, from equation (17), the amount of radial deformation at the outer periphery of the resin film plate-like member 32 having an outer diameter of 2b _sus (= 2a _{film, 2} ) _, which is the diameter of the air _diffuser 30a of the steel plate-like plate member 30. _{u afilm, sus + film,} radial deformation of the radial b _film of diffusing pores 32a of the resin film made plate member 32 with respect to _a u _{bfilm, sus + film,} the ratio of _a them to Poisson's ratio ν and 0.3 For example, Expression (18) is obtained.

The amount of deformation u _{afilm, sus + film, A} in the radial direction on the outer periphery of the resin film plate member 32 having the outer diameter of 2b _sus (= 2a _{film, 2} ) which is the diameter of the _{air diffuser} 30a of the steel plate member 30 Is equal to the radial deformation amount u _{bsus, sus} of the radius b _sus of the _{air diffuser} 30a of the steel plate-like member 30. _Therefore, using Equation (15), the radial direction of the _{air diffuser} 30a of the steel plate-like member 30 is as _follows. The amount of deformation u _{bfilm, sus + film, A} (A) in the radial direction of the _{air diffusion hole} 32a of the resin film plate-like member 32 generated by the deformation of (3) is expressed by Equation (19).

Next, the amount of deformation u _{bfilm, sus + film, B} (B) in the radial direction of the _{air diffusion hole} 32a of the resin film plate member 32 generated due to the pressure acting on the resin film plate member 32 is: From Equation (8) to Equation (20).

In the case of the air diffuser 24 in which the resin film plate member 32 is bonded to the steel plate plate member 30 with an adhesive 34 or the like, the radial direction of the fine air diffuser holes 32a at the center of the resin film plate member 32 The amount of deformation is the amount of deformation u _{bfilm, sus + film, A} (A) in the radial direction of the _{air diffusion hole} 32a of the resin film plate-like member 32 caused by the deformation in the radial direction of the _{air diffusion hole} 30a of the steel plate-like plate member 30; The sum u _bfilm of the radial deformation amount u _{bfilm, sus + film, B} (B) of the _{air diffusion hole} 32a of the resin film plate member 32 generated due to the pressure acting on the resin film plate member 32 _{, sus + film} (A + B), using equation (19) and equation (20) yields equation (21).

Furthermore, the amount of radial deformation u _{bfilm, sus + film} (A + B) of the fine air _{diffusion hole} 32a at the center of the resin film plate-like member 32 in the air diffusion portion 24 is the case where only the resin film plate-like member 32 is used. When a ratio is taken with respect to the radial deformation amount u _{film, film of the air diffusion hole} 32a of the resin film plate-like member 32, Expression (22) is obtained from Expression (8) and Expression (21).

When the gas is discharged from the fine holes in the liquid flow to generate bubbles having a radius of 50 μm or less, if the flow rate of the liquid is, for example, about several m / s, the hole diameter needs to be about 10 μm. However, assuming that the thickness of the steel plate-like member 30 is about 1 mm, it is difficult to manufacture such fine air diffusion holes 30 a in the steel plate-like member 30. Therefore, the _hole diameter 2b _sus (= 2a _{film, 2} ) of the _{diffuser hole} 30a that can be easily opened in the steel plate member 30 having a thickness of about 1 mm is considered to be about 1 mm, and the resin film plate member 32 is opened. It is assumed that the hole diameter of the air _diffusion hole 32a is about 100 times the 2b _film . The outer diameter (2a _sus ) of the steel plate member 30 is assumed to be 60 mm. Assuming in this way, the ratio of the hole radius of the air _diffuser hole 30a of the steel plate plate member 30 to the hole radius of the air diffuser hole 32a opened in the resin film plate member 32 is b _sus / b _{film ≈100.} The ratio of the hole radius of the air _diffusion hole 30a of the steel plate member 30 to the outer radius of the plate member 30 is _bsus / _asus≈1 / 60.

When these values are used, the amount of radial deformation u at the outer periphery of the resin film plate member 32 having an outer diameter of 2b _sus (= 2a _{film, 2} ) _, which is the diameter of the air _diffuser 30a of the plate member 30 made of steel plate. _{The ratio of the} amount of radial deformation u _{bfilm, sus + film, A} in the radius b _film of the _{air diffuser} 32a of the resin film plate-like member 32 to _{afilm, sus + film, A} is 35.0 minutes from the equation (18). 1 (= (2 × 100) / (0.7 × 100 ² +1.3)).

When the above values are used, the resin film plate shape with respect to the radial deformation amount _{ubfilm, film} of the _{air diffusion hole} 32a of the resin film plate member 32 in the case of only the resin film plate member 32 from the equation (22). _{Ratio of the} amount of deformation u _{bfilm, sus + film} (A + B) in the radial direction of the _{air diffusion hole} 32a at the center of the resin film plate member 32 when the member 32 is attached to the steel plate plate member 30 with an adhesive 34 or the like Becomes Equation (23).

The ratio of the longitudinal elastic coefficient of the stainless steel plate for the longitudinal elastic modulus of the polyurethane resin film is about _{E sus / E film ≒ 2 ×} 10 11/3 × 10 9 ≒ 66.6. Furthermore, when the thickness of the resin film plate member 32 is 0.5 mm and the thickness of the steel plate member 30 is 1.0 mm which is twice the thickness of the resin film plate member 32, From formula (23), a diffused portion in which the resin film-made plate-like member 32 is affixed to the steel plate-like plate-like member 30 in which the outer diameter is 60 mm and the diameter of the diffused holes 30a is 1 mm with an adhesive 34 or the like. The amount of deformation u _{bfilm, sus + film in} the radial direction of the _{air diffusion hole} 32a having a diameter of 10 μm formed at the center of the 24 resin film plate members 32 is formed by the resin film plate members 32 alone. The amount of deformation u _{bfilm, film in} the radial direction of the _{air diffusion hole} 32a having a diameter of 10 μm formed at the center of the resin film plate member 32 when the outer diameter of the resin film plate member 32 is assumed to be 60 mm. It is possible to make it as small as about 222.3.

Next, in each case where the diffuser is a single plate member 30 made of steel plate and a single plate member 32 made of resin film, the maximum deflection in the direction perpendicular to the plate surface (film surface) The amounts are compared using equation (9) and equation (16). This comparison is made on the assumption that the steel plate plate member 30 and the resin film plate member 32 are disks having the same diameter. Now, assuming that the thickness of the plate member 30 made of steel plate is twice the thickness of the plate member 32 made of resin film, the maximum deflection amount in the case of the plate member 30 made of steel plate is made of resin film due to the difference in thickness. It becomes 1/8 (= 1/2 ³ ) in the case of the plate-like member 32. The longitudinal elastic modulus E is about E _S ≈2 × 10 ¹¹ (Pa) (200 GPa) for the stainless steel plate, and about E _P ≈3 × 109 (Pa) (3 GPa) for the resin film. deflection amount is 1 67 minutes ^{(= 3 × 10 9/2} × 10 11) smaller in extent.

  Further, due to the difference between the simple support and the fixed support at the outer peripheral end, when the plate member made of steel plate is used, the amount of deformation of the air diffuser is 3.8 minutes than when the plate member 32 made of resin film is used. 1 (= 0.182 / 0.695625). Therefore, when the thickness of the resin film-made plate-like member 32 is ½ of the thickness of the steel plate-like plate-like member 30, the ratio of the maximum deflection amount in the direction perpendicular to the plate surface (film surface) is as described above. From the synergistic product of each value, in the case of the plate member 30 made of steel plate, the value is reduced to about 1/2037 in the case of the plate member 32 made of resin film.

For example, it is a resin film plate-like member 32 made of a polyurethane resin film having a longitudinal elastic modulus of E _P ≈3 × 10 ⁹ (Pa) (3 GPa), and has an outer periphery radius of 30 (mm) and a thickness of 0.5 ( mm), when the pressure applied to the plate surface (film surface) is 1 × 10 ⁵ (Pa) (0.1 MPa), the calculated value of the maximum deflection amount of the resin film plate-like member 32 is about 150 (mm). Great value.

On the other hand, for example, a plate-like member 30 made of a stainless steel plate having a longitudinal elastic modulus of E _S ≈2 × 10 ¹¹ (Pa) (200 GPa), the outer radius is 30 (mm), and the thickness is 1 (mm). When the pressure applied to the plate surface is 1 × 10 ⁵ (Pa) (0.1 MPa), the maximum amount of bending of the steel plate member 30 is about 0.074 (mm), and the influence of the bending can be almost ignored. .

  Therefore, as described above, the gas chamber 16 is provided which has a diffuser portion 24 formed on the surface of the steel plate plate member 30 and the resin film plate member 32 and receives gas therein. For example, a plurality of air diffusers 12 for allowing the gas introduced into the gas chamber 16 through the gas inflow pipe 18 to flow out as fine bubbles from the air diffuser 24 to the external fluid liquid are disposed in the liquid passage 10, for example. Necessary for air diffusion in the gas chamber 16 of the air diffuser 12 when the bubble generating device is configured so that the surfaces (air diffuser surfaces) of the air parts 24 are parallel to each other and arranged at a narrow interval. Even when a certain atmospheric pressure is applied, the amount of bending in the direction perpendicular to the steel plate plate member 30 and the resin film plate member 32 of the air diffuser 24 can be kept small. It can comprise so that it may not touch. In other words, it is possible to configure a bubble generating device in which a plurality of air diffusers 12 are densely arranged.

  Therefore, when considering a liquid passage that accommodates such a bubble generating device, such as a liquid conduit, it is possible to increase the diffused surface area of the diffuser per unit volume of the conduit, etc. It is possible to increase the amount of bubbles generated per unit volume.

  As described above, a material having a large longitudinal elastic modulus may be a material having a longitudinal elastic modulus of 50 GPa or more, and a resin may be used as a material having a small longitudinal elastic modulus. This will be described quantitatively.

When the air diffuser is formed only by the resin film-made plate-like member 32, the resin film-made plate-like member 32 is a steel plate with respect to the radial deformation amount _{ubfilm, film} of the _{air diffuser hole} 32a of the resin film-made plate-like member 32. The ratio of the amount of deformation u _{bfilm, sus + film in} the radial direction of the _{air diffuser} 32a at the center of the resin film plate member 32 in the air diffuser 24 formed by adhering to the plate member 30 with an adhesive 34 or the like Is substantially inversely proportional to the ratio E _sus / E _film of the longitudinal elastic modulus of the steel plate member 30 to the longitudinal elastic modulus of the resin film plate member 32, as shown in Equation (23). Further, the maximum deflection amount w _{sus, max} in the air diffuser 24 formed by adhering the resin film plate member 32 to the steel plate plate member 30 is as shown in Equation (16). It is inversely proportional to the longitudinal elastic modulus E _sus of 30.

As described above, the vertical elasticity coefficient E _S about 200GPa stainless steel, longitudinal elastic modulus E _P of the polyurethane resin film is about 3 GPa, for example the thickness of the resin film made plate member 32 made of a polyurethane resin film 0 When the thickness of the plate member 30 made of stainless steel plate is 1.0 mm, which is twice the thickness of the plate member 32 made of resin film, the plate member 32 made of steel plate is made of steel plate. The amount of deformation _{ubfilm, sus + film in} the radial direction of the _{air diffuser} 32a at the center of the resin film plate member 32 in the _air diffuser 24 attached to the plate member 30 with an adhesive 34 or the like is the resin film plate. It is possible to reduce the size to about 1 / 2.23 / 3 of the case of the shape member 32 alone.

Here, when a material having a longitudinal elastic modulus of 50 GPa or more is used as a plate-like member having a large longitudinal elastic coefficient having a large number of diffused holes 30a corresponding to the steel sheet plate-shaped member 30 described above, radial deformation of the diffused holes is performed. The amount can be reduced to about 1/50 of the case where the air diffuser is composed of only a resin film plate member. In addition, since the maximum deflection amount w _{sus, max} of the air diffuser can be kept to about 0.3 mm or less, the air diffuser surfaces of the air diffuser are arranged in parallel with each other. It is possible to arrange them as close as possible.

  Even if the plate-like member having a large longitudinal elastic coefficient corresponding to the steel plate-like plate member 30 is reinforced with a reinforcing member such as a rib, the deformation amount of the air diffusion holes 32a of the resin film-made plate-like member 32 can be maintained at a small value. Therefore, the diameter of the generated bubbles can be maintained at a small value.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and it goes without saying that the present invention may be implemented in various forms within the scope of the technical idea.

10 Liquid passage (pipe for liquid)
12, 12a Air diffuser 14, 14a Air diffuser body 16, 16a Gas chamber 18 Gas inflow pipe 20, 20a Opening portion 22, 22a Outer shell 24 Air diffuser 30 Steel plate plate member 30a Air diffuser 32 Resin film plate Shaped member 32a Aeration hole 34 Adhesive 36 Shield packing 40 Aeration tank 42 Pump 44 Liquid piping 46 Nozzle 48 Liquid flow forming device 50 Aeration hole 52 Plate 54 Bubble

Claims (6)

An air diffuser comprising: a gas chamber; a gas inflow pipe that allows gas to flow into the gas chamber; and an air diffuser that diffuses the inflowed gas as bubbles from the gas chamber into an external liquid. ,
The air diffuser is formed by laminating at least two plate-like members made of materials each having a large number of air diffuser holes and having different longitudinal elastic modulus, with the air diffuser communicating with each other. A hole diameter of the air diffusion hole provided in one plate-shaped member made of a large material is larger than a hole diameter of the air diffusion hole provided in the other plate-shaped member made of a material having a small longitudinal elastic coefficient. Qi device.   The one plate-like member is made of a material having a longitudinal elastic modulus of 50 GPa or more, the other plate-like member is made of a resin film, and the plate thickness of the one plate-like member is the plate thickness of the other plate-like member. The diffuser according to claim 1, wherein the diffuser is thicker.   3. The air diffuser according to claim 1, wherein the one plate-like member is arranged on the gas chamber side, and the other plate-like member is arranged on the side in contact with an external liquid.   The hole diameter of the air holes provided in the one plate-shaped member is 0.5 to 2 mm, and the hole diameter of the air holes provided in the other plate-shaped member is 30 μm or less. The air diffuser according to any one of claims 1 to 3.   An air bubble comprising a plurality of the air diffusers according to any one of claims 1 to 4, wherein the air diffusers are installed in a liquid passage so that the air diffusers of the air diffuser are parallel to each other. Generator. The air diffuser according to any one of claims 1 to 3, which is disposed so as to be immersed in the liquid in the air diffuser.
A bubble generating device comprising: a liquid flow forming device that forms a flow of liquid in the air diffusion tank along the surface of the air diffusion portion of the air diffusion device.

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