JP2002282663A - Aerator and method for controlling delivery angle of aerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling a delivery angle of an aerator capable of continuously supplying a large quantity of fine air bubbles having a homogenous size to a degree of tens of μm with reduced consumption energy and controlling the delivery angle from the aerator and to provide an aerator therefor. SOLUTION: In an aerator 1 to supply fine air bubbles to a solution 23 to be treated by delivering gas-liquid two phase flow which is formed by incorporating a gas phase into a liquid, the aerator is provided with a delivery flow forming tank 9 immersed in the solution 23 to be treated, of which the delivery port 7 opens to the bottom part 5, a liquid supply means 13 which supplies the liquid to the delivery flow forming tank 9 in the jetting direction to form swirling flow which swirls within the tank along the peripheral walls 3 of the delivery flow forming tank 9, a gas supply means 17 which introduces air into the liquid within the delivery flow forming tank 9 and a core body 19 which is arranged in the swirling axis direction of the swirling flow in the proximity of the delivery port of the delivery flow forming tank 9 and which forms a thin layered shape of the supplied air on the surface of the outer periphery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aerator for generating fine bubbles in a liquid and a method for controlling a discharge angle of the aerator.

[0002]

2. Description of the Related Art As a method for purifying water from rivers, lakes and marshes, and purifying sewage such as domestic wastewater, there is known a method utilizing the biological oxidizing action of aerobic microorganisms in a liquid to be treated. Also, in the purification treatment by such a method, it is also known that it is effective to introduce fine air bubbles into the liquid to be treated in order to activate the biological oxidizing action of aerobic microorganisms.

[0003] For example, ammonia, which is toxic to living organisms, is decomposed by the action of aerobic microorganisms (nitrite bacteria) and turned into nitrite, and nitrite is turned into nitrate by nitrate producing bacteria. In addition, nitric acid is decomposed by nitrate-reducing bacteria or causes a chemical reaction with calcium bicarbonate or magnesium bicarbonate in water, and finally is converted into nitrates such as calcium nitrate and magnesium nitrate. Nitrate is neutral and has little harm to living organisms unless the concentration is extremely high. Therefore, in order for nitrite bacteria and nitrate-producing bacteria to fully perform nitrification, sufficient oxygen must be dissolved in water.

[0004] Various bubble generating devices have been developed for such a purifying process. For example, in a method using a diffuser, the introduced gas is supplied as bubbles in the liquid through the pores. In the mechanical method, the gas introduced by the rotating blades is fragmented to generate bubbles.

In the method using a diffuser, there is a variation in bubble size due to blockage of pores, a decrease in bubble generation rate, and a limit on the amount of bubbles generated. Further, there is a drawback that, since the stirring effect is insufficient, it is impossible to treat a large volume of a liquid such as a river or a lake, even if it is effective for a limited volume of a processing solution. In addition, the mechanical method has a drawback that the energy consumption is large and the variation in the bubble size is large.

[0006] In a conventional bubble generator (hereinafter referred to as an aerator), for example, in the case of using a tube having pores arranged in a liquid tank to be treated, the bubble generator generates bubbles. There are problems that the bubble size varies and the bubble generation rate decreases, and that the amount of bubble generation is limited. In addition, there is a possibility that such blockage of the pores may occur in a relatively short time, and there is also a problem that maintenance of the aerator requires a large amount of labor.

In order to increase the degree of contribution to liquid purification, it is necessary that the generated bubbles and the liquid to be treated are well mixed. That is, the liquid containing the gas phase (gas-liquid mixed two-phase flow) discharged from the aerator is vigorously discharged into the liquid to be processed to generate bubbles, and the contact between the liquid to be processed and the bubbles is promoted by mixing. Is preferably performed.

Therefore, the present inventors have studied the above problem and developed an aerator described in Japanese Patent Application Laid-Open No. 10-230150. With this aerator, it has become possible to increase the generation efficiency of bubbles in the liquid to be treated, and to increase the contact efficiency between the bubbles generated by the stirring action of the discharge flow and the liquid to be treated.

[0009]

As a result of a study conducted by the inventors of the present application, it was found that the bubble size was small between the bubble size of the bubbles supplied into the liquid to be treated by the gas-liquid mixed flow and the actual purification performance. It was recognized that the purification performance was improved as the size became uniform. In particular, when a large number of fine and uniform bubbles of about several tens of μm were generated, the purification performance was significantly improved.

That is, even if the total amount of air sent into the liquid is the same, if the bubble size is reduced, the surface area of the bubbles sent into the liquid increases accordingly, and the contact area with the liquid increases. In addition, the floating time of the bubbles in the liquid becomes longer, and the contact time between the liquid and the bubbles becomes longer. Thereby, the dissolving efficiency of oxygen in the liquid is improved, and the contribution to the activation of the biological oxidizing action by the aerobic microorganisms is increased. Therefore, it is necessary to reduce the bubble size of the bubbles sent into the liquid to be treated for the purification treatment, while at the same time reducing the bubble size in order to improve the purification performance.

Further, in a simple cyclone type aerator in which the discharge direction of the gas-liquid mixed two-phase flow is vertically downward, air pockets are generated below the discharge port. This air pool is formed by the air once discharged being moved upward by its own buoyancy. However, if the flow rate is not uniform, large-sized bubbles are generated at a certain trigger. As described above, since the large-sized bubbles are disadvantageous in the contact area and the contact time with the liquid, generation of the bubbles must be prevented.

Further, the discharge angle of the cyclone type aerator is closely related to the mixing and stirring action in the tank. The mixing agitation intensity determines the surface renewal rate of the bubbles and the oxygen transfer rate. The performance of the aerator is evaluated by the magnitude of the product of the oxygen transfer rate and the gas-liquid interface area per unit volume. That is, an aerator that generates a large amount of fine bubbles and has high mixing and stirring strength is required. The mixing angle becomes longer as the discharge angle from the aerator becomes acute, and the mixing width becomes wider as the angle becomes obtuse. Therefore, the control of the discharge angle so as to maintain the optimum discharge angle according to the purpose is a very important operation factor for obtaining the mixing and stirring strength.

Further, if the interfacial tension at the gas-liquid interface is constant, the dispersed bubble diameter decreases in proportion to the shear stress of the flow field. Therefore, it is necessary to consider how effectively the shear stress is used for the bubble dispersion, that is, the shear stress utilization efficiency. This is also because once dispersed as bubbles, the surface energy increases and it becomes difficult to shear the bubbles into smaller bubbles. Therefore, fine bubbles must be efficiently generated by a single shear. Therefore, it is considered that making the width of the air core as small as possible in the cyclone type aerator is an effective means for generating fine bubbles.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables a large amount of fine bubbles having a uniform size of about several tens of μm to be continuously supplied to a liquid to be treated with a small amount of energy. It is an object of the present invention to provide an aerator and a method for controlling a discharge angle of an aerator which can control a discharge angle from a nozzle.

[0015]

According to a first aspect of the present invention, there is provided an aerator for discharging a gas-liquid two-phase flow formed by taking a gas phase into a liquid into a liquid to be treated. In the aerator for supplying fine bubbles to the liquid to be processed, a discharge flow forming tank immersed in the liquid to be processed with a discharge port opened at the bottom, and a tank along the peripheral wall of the discharge flow forming tank Liquid supply means for pressurizing and supplying a liquid to the discharge flow forming tank in a jetting direction in which a swirling flow circulates inside; gas supply means for introducing air into the liquid in the discharge flow forming tank; A core disposed near the discharge port of the forming tank in the direction of the swirling axis of the swirling flow, for forming the supplied air in a thin layer on the outer peripheral surface.

In this aerator, when the liquid is supplied under pressure from the liquid supply means into the discharge flow forming tank, the liquid forms a swirl flow along the peripheral wall of the discharge flow formation tank, and the swirl flow causes the gas to be supplied from the gas supply means. , A part of the introduced gas is dissolved in the liquid by the pressure. In the core provided near the discharge port of the discharge flow forming tank, bubbles are collected by buoyancy against the swirling force of the swirling flow, and a thin layered air layer is formed on the outer peripheral surface of the core. When this thin air layer is discharged together with the liquid from the discharge port of the discharge flow forming tank, the air receives a large shear force due to the flow of the liquid and is subdivided. After passing through the discharge port, the gas is released from the high-pressure liquid in the discharge flow forming tank, so that the dissolved gas precipitates as fine bubbles in the liquid to be treated. Thus, a large amount of microbubbles having a substantially uniform size is stably supplied into the liquid to be treated.

According to a second aspect of the present invention, in the aerator according to the first aspect, the core is a rod disposed from the inside of the discharge flow forming tank toward the discharge port of the discharge flow forming tank.

In this aerator, the core body is a rod arranged from the inside of the discharge flow forming tank toward the discharge port of the discharge flow forming tank, so that air bubbles gathering at the center of rotation in the discharge flow forming tank can be reliably prevented. The air layer on the surface of the core can be formed with a stable and uniform thickness. Further, it is possible to support the base end of the rod in the discharge flow forming tank and dispose only the tip in the vicinity of the discharge port, and easily configure a structure in which the support member of the rod does not interfere with the discharge flow. be able to.

The aerator according to a third aspect is characterized in that the core is formed in a cylindrical shape, and the gas supply means supplies air from inside the cylinder of the core.

In this aerator, the core has a cylindrical shape, and the gas supply means supplies air from inside the cylinder of the core, so that the core is formed between the air layer and the air guide means. It will work for both.

The aerator according to a fourth aspect is characterized in that a plurality of openings for discharging air are provided on the peripheral surface of the core body.

In this aerator, since a plurality of openings are provided in the cylindrical peripheral surface of the core body, it is possible to increase a substantial inlet area for introducing air into the discharge flow forming tank.
Even when a large amount of air is introduced, the operation can be performed smoothly and stably. In addition, since air can be introduced immediately upstream of the core on which the air layer is formed, an air layer having a uniform thickness can be easily formed on the surface of the core.

According to a fifth aspect of the present invention, in the aerator according to the fifth aspect, the core body is a rod inserted from the outside of the discharge flow forming tank to the discharge port of the discharge flow forming tank with a gap. .

In this aerator, since the core is a rod inserted from the outside of the discharge flow forming tank into the discharge port of the discharge flow forming tank, the volume of the discharge flow forming tank is reduced by inserting the core. The core can be easily detached from the discharge flow forming tank without sacrificing. Since the core is inserted into the discharge flow forming tank from the outside, a thin layered air layer is formed on the outer peripheral surface of the portion inserted into the discharge flow forming tank by the same operation as described above. Will be.

According to a sixth aspect of the present invention, the liquid supply means includes a gas-liquid mixing section for introducing air into the liquid, in the middle of a supply flow path for supplying the liquid to the discharge flow forming tank. Features.

In this aerator, the liquid supply means is provided with a gas-liquid mixing section for introducing air in the supply flow path for supplying the liquid to the discharge flow forming tank, so that the liquid flowing in the supply flow path is supplied to the liquid supply means. The gas is introduced from the gas-liquid mixing section, and the liquid and the gas are supplied to the discharge flow forming tank in a state where the liquid and the gas are mixed. This increases the chance that the gas comes into contact with the liquid, and promotes the dissolution of the gas in the liquid.

According to a seventh aspect of the present invention, in the aerator, the gas supply means is provided inside the discharge flow forming tank in the direction of the swirling axis of the swirling flow, and has a pipe for supplying air into the tank. It is characterized by.

In this aerator, the gas supply means is provided inside the discharge flow forming tank in the direction of the swirling axis of the swirling flow, and is provided with a pipe for supplying air into the tank. Is introduced into the discharge flow forming tank. Part of the air introduced into the discharge flow forming tank is dissolved in the liquid by the pressure. Then, a thin layered air layer is formed on the outer peripheral surface of the core inserted into the discharge flow forming tank from the outside, and this air layer is subdivided by receiving a large shear force by the liquid discharged from the discharge port. .

According to an eighth aspect of the present invention, in the aerator according to the present invention, the discharge flow forming tank has a circular cross section orthogonal to a swirling center axis of the swirling flow, and the liquid supply means is provided on an inner peripheral surface of the discharge flow forming tank. Are connected in a tangential direction.

In this aerator, the discharge flow forming tank has a circular cross section perpendicular to the swirl center axis of the swirling flow, and the liquid supply means is connected tangentially to the inner peripheral surface of the discharge flow forming tank. Thus, the liquid supplied from the liquid supply means flows along the inner peripheral surface of the discharge flow forming tank, and a swirling flow is formed in the tank.

According to a ninth aspect of the present invention, in the aerator according to the present invention, the bottom of the discharge flow forming tank is formed in a conical shape protruding in the direction of jetting the gas-liquid two-phase flow.

In this aerator, the bottom of the discharge flow forming tank is formed in a conical shape protruding in the direction of jetting the gas-liquid two-phase flow, so that the axial flow velocity distribution of the liquid in the vicinity of the discharge port of the discharge flow forming tank is reduced. It becomes gentle. Accordingly, the gas is carried by the axial flow of the liquid, so that the velocity distribution becomes gentle, so that the loss of work for carrying the gas is reduced, and as a result, the amount of introduced gas is increased.

An aerator according to a tenth aspect is characterized in that the gas supply means is a self-priming type for supplying air by natural suction.

In this aerator, the gas supply means is a self-priming type in which air is supplied by natural suction.
There is no need to have a separate drive source for the gas supply operation,
Stable supply of fine bubbles can be achieved with low energy consumption. Further, the aerator can be manufactured with a simple and low-cost configuration. Further, in the case of the self-priming type, the amount of air according to the amount of liquid supplied from the liquid supply means is constantly adjusted to an appropriate amount while being changed following the fluctuation of the amount of supplied liquid.

An aerator according to an eleventh aspect of the present invention is characterized in that the gas supply means is of a forced blowing type for supplying air under pressure.

In this aerator, the gas supply means is of a forced blowing type that supplies air under pressure, so that a desired amount of gas can be forcibly introduced into the discharge flow forming tank. Therefore, when the required maximum air supply amount is not ensured by the self-priming type, the required maximum air supply amount can be supplied by forcibly feeding air.

According to a twelfth aspect of the present invention, there is provided a method of controlling a discharge angle of an aerator using the aerator according to any one of the first to eleventh aspects, wherein the core is inserted into a discharge flow forming tank. The discharge angle of the gas-liquid two-layer flow discharged from the discharge port of the discharge flow forming tank is controlled based on the ratio between the diameter of the body cylinder and the discharge port diameter of the discharge flow forming tank.

In this method of controlling the discharge angle of the aerator,
The discharge angle of the gas-liquid two-layer flow discharged from the discharge port of the discharge flow forming tank is controlled based on the ratio between the cylindrical diameter of the core inserted into the discharge flow forming tank and the discharge port diameter of the discharge flow forming tank. Thereby, an arbitrary ejection angle can be easily obtained. Therefore, it is possible to easily set the discharge angle suitable for the purpose of use of the aerator, and to maximize the function of the aerator.

According to a thirteenth aspect of the present invention, in the method for controlling the discharge angle of the aerator, the cylindrical diameter of the core is d _r , the discharge opening diameter of the discharge flow forming tank is d ₀ , and the discharge angle when the core is not inserted is θ.
When set to _0, the jetting angle θ _r, θ _r = tan ^-1
And setting by _{[{1- (d r / d 0} ) 2} · tanθ 0 ].

In this method of controlling the discharge angle of the aerator,
A cylinder diameter of the core d _r, the discharge port diameter of the discharge flow forming tank d _0,
Assuming that the discharge angle of the field base where the core body is not inserted is θ ₀ , the discharge angle θ _r is represented by θ _r = tan ⁻¹ [｛1− (d _r / d ₀ )
² ｝ · tan θ ₀ ], the discharge angle of the gas-liquid two-layer flow discharged from the discharge port of the discharge flow forming tank is determined by easily settable parameters (cylinder diameter _dr , discharge port diameter d ₀ ). It can be set substantially arbitrarily.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an aerator and a method for controlling a discharge angle of the aerator according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a side view showing a first embodiment of an aerator according to the present invention, and FIG.
FIG. 3 is a perspective view of the aerator of FIG.
FIG. 4 is an explanatory view showing examples of the tip shape of the core of the aerator of FIG. 1 in (a) to (c), and FIG. 5 is formed on the outer peripheral surface of the core of the aerator of FIG. FIG. 2 is a horizontal sectional view of an air layer to be formed.

As shown in FIGS. 1 and 2, in the aerator 1 according to the present embodiment, the peripheral wall 3 is formed in a cylindrical shape, and the bottom 5 is formed in a disk shape perpendicular to the axis of the peripheral wall 3. 5, a discharge flow forming tank 9 having a discharge port 7 opened at the center position, a liquid supply unit 13 for supplying the liquid W into the discharge flow forming tank 9 through a pipe 11, and a discharge through a pipe 15. A gas supply means 17 for introducing air G into the flow forming tank 9 by natural suction, and a core 19 disposed in the axial direction of the discharge flow forming tank 9 near the discharge port 7 of the discharge flow forming tank 9 are provided. ing. In this embodiment, the aerator 1 is arranged so that the axis of the discharge flow forming tank 9 is vertical.
Is located within.

The processing tank 21 has a volume corresponding to the processing performance of the aerator 1, and as the required processing amount increases or decreases, a processing capacity or an individual aerator corresponding to the processing amount is used as appropriate. Alternatively, a processing tank having a volume corresponding to the processing performance of the aerator is appropriately selected.

The liquid supply means 13 is connected to a pipe 11 communicating with the discharge flow forming tank 9, and a pump (not shown), and pressurizes and supplies the liquid W to the discharge flow forming tank 9 in a state where the pressure is increased. In this embodiment, the liquid supply means 13
The liquid W supplied to the discharge flow forming tank 9 is the same as the liquid to be processed 23 stored in the processing tank 21, but is not limited thereto and may be another liquid.

The connection angle of the pipe 11 to the discharge flow forming tank 9 defines the direction in which the liquid W to be supplied to the discharge flow forming tank 9 is ejected. As shown in FIG. It is set so as to form a swirling flow that swirls in the tank along the peripheral wall of the flow forming tank 9. That is, in the present embodiment, the pipe 11 is connected to the inner peripheral surface of the discharge flow forming tank 9 in a tangential direction. As a result, the liquid W supplied from the liquid supply means 13 flows along the inner peripheral surface of the discharge flow forming tank 9, thereby forming a swirling flow in the direction of arrow a in the tank.

In this embodiment, as shown in FIG.
Is formed as a cylindrical body 25 arranged toward the first. The distal end (the lower end in FIG. 2) of the cylindrical body is a solid rod 27. That is, the tip of the cylinder 25 is closed by the rod 27. The rod body 27 is arranged concentrically with the discharge port 7 such that the front end surface (the lower end surface in FIG. 2) is substantially flush with the bottom 5. Therefore, the discharge port 7 is formed as an annular gap between the outer periphery of the rod 27 and the inner periphery of the discharge port 7. In addition, although the cylindrical body 25 and the rod body 27 are formed with the same outer diameter, and the outer peripheral surfaces of both are continuously formed without a step, a step may be provided.

As shown in FIG. 4A, the rod 27 has a flat shape 27 formed by a plane perpendicular to the axis.
a. In addition, the rod 27 has a tip shape shown in FIG.
FIG. 4C shows a conical pointed shape 27b shown in FIG.
As shown in the figure, a pointed shape 2 having a narrow flat portion at the tip end
7c.

The pipe 15 of the gas supply means 17 is connected to the base end of the cylinder 25. That is, the core 19
The air G is supplied to the cylindrical body 25. A plurality of openings 29 are formed in the outer peripheral surface of the cylindrical body 25. Therefore, the cylinder 2
The air G supplied to the air supply 5 is supplied to the discharge flow forming tank 9 through the opening 29. The other end of the gas supply means 17 is open to the atmosphere, and is of a self-priming type in which air at atmospheric pressure is introduced into the discharge flow forming tank 9 by natural suction.

In such a self-priming type gas supply means 17, it is not necessary to provide a separate driving source for the gas supply operation, and stable supply of fine bubbles can be achieved with low energy consumption. Further, the aerator can be manufactured with a simple and low-cost configuration. Furthermore, in the case of the self-priming type, the liquid supply means 1
The amount of air according to the amount of supply liquid from No. 3 varies following the fluctuation of the amount of supply liquid, and is constantly adjusted to an appropriate amount to be supplied stably. Although not shown, if a control valve for adjusting the air introduction amount is provided in the middle of the pipe line 15, the air introduction amount can be adjusted.

Further, the gas supply means 17 may be of a forced blowing type for supplying air under pressure. Gas supply means 17
Is a forced blowing type, a desired amount of gas can be forcibly introduced into the discharge flow forming tank 9. Therefore,
If the required maximum air supply cannot be secured with the self-priming type,
The required maximum air supply amount can be supplied by forced air supply.

Next, the operation of the aerator 1 will be described. In the aerator 1 having the above structure, the swirling flow shown in FIG. 3 is formed in the discharge flow forming tank 9 by pressurizing and supplying the liquid W to the discharge flow forming tank 9 by the liquid supply means 13 as shown in FIG. Is done. After the swirling flow turns on the inner peripheral surface of the discharge flow forming tank 9, the swirling flow flows out of the discharge port 7, and in the discharge flow forming tank 9, the pressure at the center decreases due to the centrifugal force due to the turning. Therefore, the air G is introduced into the liquid in the tank by the suction action from the opening 29 of the cylindrical body 25 to the discharge flow forming tank 9. Part of the air G introduced at this time is dissolved in the liquid by the pressure. On the other hand, most of the introduced air is collected by buoyancy against the swirling force of the swirling flow, and forms an air layer 31 in a thin layer on the outer peripheral surface of the rod 27 as shown in FIG.

The thin layered air layer 31 formed on the outer peripheral surface of the rod 27 receives a large shear force due to the flow of the liquid when it is discharged together with the liquid from the discharge port 7 of the discharge flow forming tank 9. It is finely divided and becomes fine bubbles and is injected into the liquid to be treated. Further, the air dissolved in the liquid passes through the discharge port 7 and is released from the high-pressure liquid in the discharge flow forming tank 9 so as to precipitate as fine bubbles in the liquid to be treated. By the gas-liquid two-phase flow jetted from the discharge port 7 in this manner, a large amount of microbubbles of substantially uniform size are stably supplied into the liquid to be treated.

In such an aerator 1, the interfacial tension of gas-liquid in the gas-liquid mixed two-phase flow discharged from the discharge port 7 of the discharge flow forming tank 9 is σw / g, and is formed on the outer peripheral surface of the rod 27. The shear stress at the interface 33 (see FIG. 5) between the generated air layer 31 and the liquid 23 to be treated outside the discharge flow forming tank 9 is represented by S, and the bubbles generated in the gas-liquid mixed flow 35 (see FIG. 1). If the diameter is da, the following equation holds. da = 4 (σw / g) / S

That is, as the shear stress S increases and the gas-liquid interfacial tension σw / g decreases, the gas-liquid mixed two-phase flow is discharged from the discharge port 7 of the discharge flow forming tank 9. The bubble size in the gas-liquid mixed flow is reduced, and the variation in the bubble size is suppressed. Further, the mixing ratio of bubbles in the generated gas-liquid mixed flow 35 is also increased. Therefore, in order to obtain a large amount of small-sized bubbles, it is necessary to increase the shear stress S at the interface 33 between the gas-liquid mixed two-phase flow and the liquid 23 to be treated and to decrease the gas-liquid interface tension σw / g. Becomes important. According to the aerator 1 of the present embodiment, by forming the thin layered air layer 31 on the outer peripheral surface of the rod 27, the air layer 31 receives a large shearing force by the liquid discharged from the discharge port 7. And it is finely divided efficiently by a single shear to form fine bubbles.

As described above, according to the aerator 1 described above, the gas discharged by the gas supply means 17 is supplied to the rod 27.
Is formed as a thin layered air layer 31 on the outer peripheral surface of
When the air layer 31 receives a large shear force by the liquid discharged from the discharge port 7, fine bubbles can be generated stably. Thereby, miniaturization of the bubble size and reduction of the variation in the bubble size are achieved.

Further, since the pressure of the liquid is increased by the liquid supply means 13 to introduce the air into the liquid, the dissolution of the air into the liquid is promoted. Further, since the air introduced into the discharge flow forming tank 9 increases the chance of contact between the air and the liquid due to the swirling flow, the dissolution into the liquid is promoted. For this reason,
When the gas-liquid two-phase flow is diffused and jetted from the discharge port 7 of the discharge flow forming tank 9, the decompression action promotes the precipitation (bubbling) of the dissolved gas in the liquid.

Further, the swirling force of the liquid supplied into the discharge flow forming tank 9 by the liquid supply means 13 compresses the gas flow in the direction of the swirling center, thereby reducing the pressure when the gas is discharged from the discharge flow forming tank 9. It also plays a role of promoting the deposition of gas and the formation of fine particles, thereby increasing the mixing ratio of bubbles in the gas-liquid mixed flow 35.

As described above, in the aerator 1 of the present embodiment, the above-mentioned effects act synergistically,
It is possible to stably supply a large amount of microbubbles having a diameter of about several tens of μm at a constant size. Further, the energy for the flow of the liquid and the gas and the dispersion of the bubbles are small, so that the dissipative energy of the entire apparatus can be reduced and the noise can be reduced. Then, since the liquid is pressurized and supplied, the agitating action of the liquid is improved, the relative speed between the liquid and the bubbles is increased, the renewal speed of the surface coating of the bubbles is increased, and the moving speed of oxygen into the liquid to be treated is increased. Can be improved.

If this aerator 1 is used for purification processing, excellent purification performance can be obtained, and at the same time, the size and cost of the purification device can be reduced. The aerator 1 is operated by combining a plurality of discharge flow forming tanks 9 each having a core body 19 and branching and connecting a single liquid supply unit 13 and a single gas supply unit 17. You can also. Therefore, it can be easily adapted to large-capacity processing such as purification of rivers and lakes.

The shape of the discharge flow forming tank 9 is not limited to the cylindrical shape in the present embodiment, and the liquid supplied by the liquid supply means becomes a swirling flow that swirls in the tank along the peripheral wall. For example, the shape may be an ellipsoid or a sphere. That is, the shape of the discharge flow forming tank 9 is
Any shape may be used as long as the cross section orthogonal to the center axis of the swirling flow is formed in a circular shape.

Next, a description will be given of a second embodiment of the aerator according to the present invention. FIG. 6 is a side view showing a second embodiment of the aerator according to the present invention. In the aerator 41 according to this embodiment, the cores 19 provided in the discharge flow forming tank 9 are all solid rods 27. That is, the cylindrical body 25 and the opening 29 formed by the aerator 41 are not formed in the core body 19. On the other hand, the liquid W is supplied under pressure to the liquid supply port 45a and the air G is supplied from the gas supply port 45b by the flow of the liquid W to the pipeline 11 of the liquid supply means 13 connected to the discharge flow forming tank 9. An aspirator 45 as gas-liquid mixing means for forming a gas-liquid mixed flow in which a gas is mixed in a liquid by natural suction is provided. The gas-liquid mixed flow from the aspirator 45 becomes a swirling flow that swirls inside the tank along the peripheral wall of the discharge flow forming tank 9 through the pipeline 11 and is supplied to the discharge flow forming tank 9 under pressure. Other configurations are the same as those of the aerator 1 described above.

The aspirator 45 supplies the liquid under pressure to a liquid supply port 45a, and the gas supply port 45b
And a gas-liquid mixed flow is injected and supplied to the discharge flow forming tank 9 by natural suction. In addition, it is preferable to provide a control valve (not shown) for adjusting the air flow rate in the middle of the gas introduction pipe connected to the gas supply port 45b of the aspirator 45. By providing this control valve, the aspirator 45
By adjusting the amount of air introduced into the aerator 41, the bubble size can be kept fine and constant even when the shape of the aerator 41 and operating conditions fluctuate. In addition, it is possible to adjust the operating conditions so as to be appropriate according to the use environment, and it is possible to always operate the aerator in an optimum state.

According to the aerator 41 provided with the aspirator 45, a gas is introduced from the aspirator 45 into the liquid flowing through the liquid supply means 13 and supplied to the discharge flow forming tank 9 in a state where the liquid and the gas are mixed. Can be. This increases the chance that the gas comes into contact with the liquid, and promotes the dissolution of the gas in the liquid.

Next, a description will be given of a third embodiment of the aerator according to the present invention. FIG. 7 is a side view showing a third embodiment of the aerator according to the present invention. As shown in FIG. 7, the aerator 51 according to this embodiment
Is a solid rod 53 inserted from the outside of the discharge flow forming tank 9 into the discharge port 7 of the discharge flow forming tank 9 with a gap. The rod 53 according to this embodiment has a conical pointed shape at the tip (upper end in FIG. 7). That is,
The liquid discharged from the discharge flow forming tank 9 flows through the annular gap between the outer periphery of the rod 53 and the inner periphery of the discharge port 7 to be processed liquid 2.
3 is injected. Therefore, in the case of this configuration, since the rod 53 is inserted into the discharge flow forming tank 9 from the outside, a thin layered structure is formed on the outer peripheral surface of the portion inserted into the discharge flow forming tank 9 by the same action as described above. Is formed.

In a modified example 51a shown in FIG. 7A, a pipe 15 is provided in the discharge flow forming tank 9 in the axial direction.
The distal end of the pipe 15 serves as a gas introduction port 55 and faces the discharge port 7 of the discharge flow forming tank 9. A nozzle (not shown) for stabilizing the introduction of air may be provided at the tip of the gas introduction port 55. The other end of the pipe 15 is open to the atmosphere, and air at atmospheric pressure is introduced into the discharge flow forming tank 9 by natural suction. Although not shown, it is preferable to provide a control valve for adjusting the amount of air introduced in the pipe 15.

In the modification 51b shown in FIG. 7B, the pipe 15 in the discharge flow forming tank 9 is omitted, and instead, the liquid supply means 13 is provided with the same aspirator 4 as described above.
5 are interposed. The other configuration is the same as that of the above-described modification 51a. Although not shown, the aerator according to the present invention has a gas inlet 55 shown in FIG.
7 and the aspirator 45 shown in FIG. 7 (b). With such a configuration, air is supplied from both the gas inlet 55 and the aspirator 45, and the efficiency of supplying air into the discharge flow forming tank 9 can be increased.

According to this aerator 51, the core 19
Is a rod 53 inserted into the discharge port 7 from the outside of the discharge flow forming tank 9, so that the core 19 is inserted without sacrificing the volume of the discharge flow forming tank 9, and
Can be easily detached from the discharge flow forming tank 9.

Next, a fourth embodiment of the aerator according to the present invention will be described. 8 and 9 are side views showing a fourth embodiment of the aerator according to the present invention. In the aerator 61 according to this embodiment, the bottom 63 of the discharge flow forming tank 9 is formed in a conical shape that protrudes in the jet direction of the gas-liquid two-phase flow. Therefore, in the discharge flow forming tank 9, the swirling flow is configured to smoothly go to the discharge port 7.

The modification 61a shown in FIG.
Is a cylindrical body 2 similar to the aerator 1 of the first embodiment.
There is provided a core body 19 composed of 5 and a rod 27. Also,
In a modification 61b shown in FIG. 8B, a solid core 19 is provided inside the discharge flow forming tank 9 similarly to the aerator 41 of the second embodiment, and the aspirator 45 is provided to the liquid supply means 13. Is interposed. In a modification 61c shown in FIG. 9A, a rod 53 is provided outside the discharge flow forming tank 9 similarly to the aerator 51 of the third embodiment (see FIG. 7A). In the discharge flow forming tank 9, a pipe 15 in which the gas introduction port 55 faces the discharge port 7 is provided. Also,
A modification 61d shown in FIG. 9B is a rod 53 similar to the aerator 51 of the third embodiment (see FIG. 7B).
Is provided outside the discharge flow forming tank 9 and the liquid supply means 13 is provided.
Is provided with an aspirator 45.

According to this aerator 61, the bottom 63 of the discharge flow forming tank 9 is formed in a conical shape protruding in the direction of jetting the gas-liquid two-phase flow. , The axial flow velocity distribution becomes gentle, the pressure drop at the swirling center of the liquid increases, and the amount of gas introduced can be increased. For this reason, it is possible to provide a configuration of an aerator that requires less power and has high energy efficiency. In the case of the modification 61c, the axial flow velocity distribution of the liquid in the vicinity of the gas introduction port 55 becomes gentle, and the suction force is large and stable. Accordingly, the gas introduction amount can be increased.

Next, a method of controlling the discharge angle of the aerator will be described. The discharge angle control method of this aerator is as follows.
The aerator 1 according to the above-described first to fourth embodiments,
Discharge from the discharge port 7 of the discharge flow forming tank 9 based on the ratio of the cylindrical diameter of the core inserted into the discharge flow forming tank 9 to the discharge port diameter of the discharge flow forming tank 9 using 41, 51, 61. It is characterized in that the discharge angle of the gas-liquid two-layer flow is controlled.

[0072] That is, the cylinder diameter d _r of the core, d ₀ a discharge port diameter of the discharge flow forming chamber 9, when the ejection angle in the case of not inserting the core and the theta _0, the discharge angle theta _r, theta _r = tan ^-1 [{1- (d _r / d ₀ ) ² }｝ tan θ ₀
], The discharge angle of the gas-liquid two-layer flow discharged from the discharge port 7 can be controlled.

Here, it is assumed that the diameter of the air core formed in the cyclone type aerator is determined by Bernoulli's law for the axial velocity when the orifice surface is the inspection surface. Although this assumption has a strict error due to the fact that there is suction due to the tangential velocity, it will be recognized as a simple method for estimating the size of the air core. From Bernoulli's law,

[0074]

(Equation 1)

[0075]

(Equation 2)

Where ν _a is the air flow velocity, ν _w is the water flow velocity, ρ
_a represents air density, [rho _w water density, d ₀ is the orifice diameter, d _a is the air core diameter, Q _a is the air flow rate, Q _w is the water flow rate, a. Now, the aeration rate ψ _a

[0077]

(Equation 3)

## EQU10 ## From the equations (1) to (3),

[0079]

(Equation 4)

Is derived. As is apparent from the equation (4), the air core diameter increases with an increase in the air mixing ratio, and it becomes difficult to receive the shear stress uniformly. It is presumed that the discharge flow curves outward with the increase of the air mixing ratio due to the expansion of the air core. On the other hand, in order to supply the air core to the shear plane so as to receive the shear stress uniformly, it is expected that the width of the air core is reduced and at the same time, the air core is supplied close to the shear plane by the water flow. To do so, a cylinder is placed at the center of the air core and air flows along its surface. When the diameter of the cylinder to be inserted is dr, the diameter of the apparent air core including this cylinder is d _a ^*, and Bernoulli's law is applied,

[0081]

(Equation 5)

Is obtained. If c = 0 in equation (5), equation (4) is obtained. FIG. 10 shows the relationship between the air mixing ratio ψ _a and the apparent air core diameter d _a ^* / d _{0 using} c as a parameter in the equation (5). Increasing the apparent air core diameter increases the axial velocity of the water passing through the orifice, while increasing the shear velocity with little effect on the cut-line velocity. The actual airflow width b based on the orifice diameter is

[0083]

(Equation 6)

Therefore, the result is as shown in FIG. Figure 1
As can be seen from FIG. 1, if the air mixing ratio is the same, as the diameter of the inserted cylinder increases, the width of the air flow decreases, and the shearing stress is more easily received uniformly. When a cylinder is inserted, changes in the water flow velocity and the air velocity are as shown in FIG. 12 when viewed at a specific axial direction velocity based on the case without the cylinder. The specific axial velocity shows the same value for water and air. This means

[0085]

(Equation 7)

This is clear from the above. FIG. 13 shows the discharge angle. FIG. 13 shows how the discharge angle when no cylinder is inserted changes depending on the size of the inserted cylinder (diameter of cylinder / diameter of orifice).

[0087]

(Equation 8)

Is obtained from However, in practice, when the insertion cylinder is made larger, the discharge flow is sucked by the air flow, the discharge angle shifts to the acute angle side, and the mixing distance should be longer. It can be seen that the insertion cylinder facilitates the generation of fine bubbles, which can also be used to control the angle of the discharge flow. That is, since the axial velocity of the water is increased by inserting the column, the discharge angle can be kept on the acute angle side. Therefore, the mixing distance of the discharge flows can be increased. Further, when the insertion cylinder is extended to the discharge flow side, the pressure inside the discharge flow can be made lower than that outside, and the discharge flow is further attracted to the cylinder side. By selecting the diameter and length of the insertion cylinder in this way, it is possible to realize optimal aeration.

As is apparent from the above verification, according to this method of controlling the discharge angle of the aerator, the ratio of the diameter of the cylinder inserted into the discharge flow forming tank to the diameter of the discharge opening of the discharge flow forming tank is determined. By controlling the discharge angle of the gas-liquid two-layer flow discharged from the discharge port of the discharge flow forming tank, an arbitrary discharge angle can be easily obtained. Therefore, it is possible to easily set the discharge angle suitable for the purpose of use of the aerator, and to maximize the function of the aerator.

Then, the column diameter of the core is d_r , Discharge flow formation
The discharge diameter of the tank is d₀ , The discharge angle of the base without inserting the core
θ₀ And the discharge angle θ_r And θ_r = Tan
^-1[｛1- (d_r / D₀ )^Two ｝ ・ Tanθ₀ ]
The air discharged from the discharge port of the discharge flow forming tank
The discharge angle of the two-layer liquid can be easily set using a parameter (cylinder diameter
d _r , Discharge port diameter d₀ ) Allows virtually any setting
It will work.

[0091]

As described above in detail, according to the aerator according to the present invention, the vicinity of the discharge port of the discharge flow forming tank is
Since the core body that forms the supplied air in a thin layer on the outer peripheral surface is disposed in the direction of the swirling axis of the swirling flow, a thin air layer can be formed around the pillar without forming an air pocket. By discharging the thin air layer together with the liquid from the discharge port of the discharge flow forming tank, even if the shear force generated by the water flow is the same, the thin air layer acts as a large shear force to finely subdivide the air. Can be. In addition, the provision of the core increases the discharge resistance and applies a back pressure inside the discharge flow forming tank. As the internal pressure increases, the amount of air dissolved in the liquid increases. Then, when the liquid in which the air is dissolved is ejected from the discharge port and the pressure is reduced, the dissolved air precipitates and fine bubbles are generated. Therefore, the effect of subdividing these thin air layers and the effect of increasing the amount of dissolved air in the liquid act synergistically, and it is possible to stably supply a large amount of microbubbles having a substantially uniform size into the liquid to be treated.

According to the method for controlling the discharge angle of the aerator according to the present invention, the cylindrical diameter of the core inserted into the discharge flow forming tank,
The discharge angle of the gas-liquid two-layer flow discharged from the discharge port of the discharge flow forming tank can be easily controlled based on the ratio with the discharge port diameter of the discharge flow forming tank. The mixing agitation intensity can be obtained, and by performing control in combination with the air core width described above, the function of the aerator can be maximized by adapting to any purpose.

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of an aerator according to the present invention.

FIG. 2 is a partially cutaway perspective view of the aerator of FIG. 1;

FIG. 3 is a horizontal sectional view of the aerator of FIG. 1;

4 (a) to 4 (a) to 4 (c) show examples of the core tip shape of the aerator of FIG.
It is explanatory drawing shown in (c).

5 is a horizontal cross-sectional view of an air layer formed on the outer peripheral surface of the core of the aerator of FIG. 1;

FIG. 6 is a side view showing a second embodiment of the aerator according to the present invention.

FIG. 7 is a side view showing a third embodiment of the aerator according to the present invention.

FIG. 8 is a side view showing a fourth embodiment of the aerator according to the present invention.

FIG. 9 is a side view showing a fourth embodiment of the aerator according to the present invention.

FIG. 10 is a diagram illustrating the effect of the diameter of the inserted cylinder on the apparent air core diameter.

FIG. 11 is a diagram illustrating the effect of the insertion cylinder diameter on the air flow width.

FIG. 12 is a diagram illustrating an increase in axial speed due to insertion of a cylinder.

FIG. 13 is a diagram illustrating the effect of the insertion cylinder on the discharge angle.

[Explanation of symbols]

1, 41, 51, 61 Aerator 3 Peripheral wall 5, 63 Bottom 7 Discharge port 9 Discharge flow forming tank 11, 15 Pipe 13 Liquid supply means 17 Gas supply means 19 Core body 23 Liquid to be treated 27, 53 Rod 29 Opening 35 Gas-liquid two-phase flow 45 Aspirator (gas-liquid mixing part) d ₀ Discharge port diameter d _r Cylinder diameter θ ₀ Discharge angle when core is not inserted θ _r Discharge angle W Liquid

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tokumitsu Kadota 8-1 Hirai Hiraicho, Nishitama-gun, Tokyo Nippon Steel Mining Co., Ltd. (72) Michio Nonaka 1-31-20 Shimotakaido, Suginami-ku, Tokyo F-term (Reference) 4D029 AA09 AB03 AB06 BB11 4G035 AB05 AB16 AE02 AE13

Claims (13)

[Claims] 1. An aerator that supplies fine gas bubbles to a liquid to be processed by discharging a gas-liquid two-phase flow formed by taking a gas phase into a liquid into the liquid to be processed. A discharge flow forming tank immersed in the liquid to be treated, and supplying the liquid to the discharge flow forming tank by pressurization in a jetting direction that forms a swirling flow swirling in the tank along the peripheral wall of the discharge flow forming tank. A liquid supply unit, a gas supply unit that introduces air into the liquid in the discharge flow forming tank, and a liquid supply unit that is disposed in the direction of the swirling axis of the swirling flow near the discharge port of the discharge flow forming tank. A core for forming air in a thin layer on the outer peripheral surface. 2. The aerator according to claim 1, wherein the core is a rod disposed from the inside of the discharge flow forming tank toward a discharge port of the discharge flow forming tank. 3. The aerator according to claim 1, wherein said core body has a cylindrical shape, and said gas supply means supplies air from inside the cylinder of said core body. 4. The aerator according to claim 3, wherein a plurality of openings for discharging air are provided on a peripheral surface of the core body. 5. The aerator according to claim 1, wherein the core is a rod inserted from the outside of the discharge flow forming tank into the discharge port of the discharge flow forming tank with a gap. . 6. The liquid supply device according to claim 1, further comprising a gas-liquid mixing section for introducing air into the liquid in a supply flow path for supplying the liquid to the discharge flow forming tank. The aerator according to any one of claims 2 to 5. 7. The gas supply means is provided inside the discharge flow forming tank in the direction of the swirling axis of the swirling flow, and has a pipe for supplying air into the tank. The aerator according to claim 5 or claim 6. 8. The discharge flow forming tank has a circular cross section perpendicular to the swirling center axis of the swirling flow, and the liquid supply means is tangential to an inner peripheral surface of the discharge flow forming tank. The aerator according to any one of claims 1 to 7, wherein the aerator is connected. 9. The method according to claim 1, wherein the bottom of the discharge flow forming tank is formed in a conical shape protruding in the direction of jetting the gas-liquid two-phase flow. Aerator. 10. The self-priming type gas supply means for supplying air by natural suction.
The aerator according to any one of claims 9 to 9. 11. The gas supply means is of a forced blowing type for supplying air under pressure.
The aerator according to claim 9. 12. A discharge angle control method using an aerator according to any one of claims 1 to 11, wherein a diameter of a cylindrical body of a core inserted into a discharge flow forming tank, and the discharge flow forming tank. A discharge angle control method for an aerator, comprising controlling a discharge angle of a gas-liquid two-layer flow discharged from a discharge port of a discharge flow forming tank based on a ratio of the discharge port diameter to a discharge port diameter. 13. When the diameter of the cylinder of the core is d _r , the diameter of the discharge port of the discharge flow forming tank is d ₀ , and the discharge angle when the core is not inserted is θ ₀ , the discharge angle θ _r is defined as , θ _r = tan ^-1 _{[{1- (d r / d 0} ) 2} · tanθ
_The method for controlling a discharge angle of an aerator according to claim 12, wherein: