JPH05123555A - Method for generating fine air bubbles and apparatus therefor - Google Patents

Abstract

PURPOSE:To simply and variably set the mean diameter of formed air bubbles and the diameter range thereof corresponding to various demands. CONSTITUTION:A liquid nozzle and an ejector type gas nozzle 3 having a gas nozzle are used and a liquid B is injected in a liquid A to be aerated from the liquid nozzle and air is sucked in the liquid A to be aerated from the gas nozzle of the ejector type gas nozzle 3 by the negative pressure due to the jet stream of the liquid to generate fine air bubbles in the liquid A to be aerated. In this fine air bubble generating method, the flow rate and pressure of the liquid B supplied from the liquid nozzle are individually controlled quantitatively and variably and, by this control, the jet speed of the liquid B injected in the liquid A to be aerated from the liquid nozzle is variably set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a Newton viscous fluid,
TECHNICAL FIELD The present invention relates to a fine bubble generating method and a fine bubble generating apparatus for generating fine bubbles in various liquids of non-Newtonian viscous fluid, such as air, inert gas, other various gases, and aromatic gases, and more specifically, an ejector type The present invention relates to a fine bubble generating method and a fine bubble generating device using a gas nozzle.

[0002]

BACKGROUND ART sponge cake, light snowfall cans, whipped cream, ice cream, as mayonnaise, air in the food, odorless gas such as N _2, CO _2, an inert gas, or a gas which has been added flavor components When it is included in the food main ingredient as fine air bubbles, its digestion and absorption, texture is improved, sensory functions such as mild taste are improved, and further oxidation and deterioration of food are suppressed. It is known that the effect of

Further, by blowing fine air bubbles into the fertilizing solution in hydroponics, fresh water in seafood culture, and seawater, the dissolved oxygen concentration in these liquids is increased to promote the growth of plants and animals. It is also known.

By the way, conventionally, the foaming treatment for non-Newtonian viscous liquids such as water, edible oil and the like, or suspension-like dispersion liquid of egg yolk / white and wheat flour, gelatin solution, dissolved chocolate, fresh cream liquid and the like is performed manually. It is carried out by a mechanical or electric stirring whisk, a stirring foaming machine, or the like.

As a technique for blowing fine bubbles into a liquid for the purpose of increasing the dissolved oxygen concentration in the liquid, increasing the gas-liquid reaction rate, etc., a gas having a porous structure is used to disperse the gas and jet it into the liquid. Those that rotate a rotating body with blades to shear and divide gas to generate bubbles, those that resonate liquid to make bubbles smaller, those that change the liquid pressure of liquid to make bubbles smaller, etc. , Various techniques have been proposed.

[0006]

The diameter of the bubbles obtained by the manual or electric stirring and whisk or the stirring foaming device is about 200 to 800 μm, and the shape of the stirring member is improved. However, it is difficult to stably generate finer bubbles with a stirring whisk and an agitating foamer. In addition, the above has a problem that the foaming speed is slow in the generation of fine bubbles, a lot of time is required to generate a large amount of fine bubbles, and power consumption is large.

Further, in the above-mentioned prior art in which fine bubbles are blown into the liquid for the purpose of increasing the concentration of dissolved oxygen in the liquid, the diameter of the bubbles generated is about 0.1 to 5 mm, and more than this. It is difficult to generate such fine bubbles, and therefore, there is a limit in increasing the dissolved oxygen concentration, increasing the gas-liquid reaction rate, and the like.

In view of the above problems, the bubble diameter is 10
A micro-bubble generating device capable of stably and continuously generating micro-bubbles of up to 200 μm at a high speed is disclosed in Japanese Patent Application No. 60-30257 (Japanese Patent Publication No. 1-33211).
No.). This fine bubble generator uses an ejector type gas nozzle having a liquid nozzle and a gas nozzle, ejects a liquid from the liquid nozzle into the liquid to be foamed, and generates a gas from the gas nozzle by the negative pressure due to the jet flow of the liquid. It is sucked into a liquid, and at that time, a microscopic bubble is generated in the liquid to be foamed by a shearing action acting on a gas flow.

According to the present invention, in the fine bubble generator using the above ejector type gas nozzle, the average diameter and the bubble diameter range of the generated bubbles can be easily and variably set to appropriate values according to various requirements. An object of the present invention is to provide a fine bubble generating method and a fine bubble generating device.

[0010]

According to the present invention, an ejector type gas nozzle having a liquid nozzle and a gas nozzle is used, and the liquid is ejected from the liquid nozzle into the liquid to be foamed. By the negative pressure due to the jet of
A method for generating fine bubbles in which the gas from the gas nozzle is sucked into the liquid to be foamed to generate fine bubbles in the liquid to be foamed, and the flow rate of the gas to be supplied to the gas nozzle is quantitatively and variably controlled. This is achieved by a method for generating fine bubbles, which is characterized in that the diameter of fine bubbles generated in the foaming liquid is controlled.

In order to achieve the above-mentioned object, the fine bubble generator according to the present invention has an ejector type gas nozzle provided with a liquid nozzle and a gas nozzle, and ejects the liquid from the liquid nozzle into the liquid to be foamed. , A negative pressure due to the jet of the liquid causes a gas from the gas nozzle to be sucked into the liquid to be foamed to form a fine bubble generator for generating fine bubbles in the liquid to be foamed, and to supply gas to the gas nozzle. It is characterized by having a gas flow rate control valve for quantitatively controlling the flow rate.

[0012]

According to the above construction, the flow rate of the gas supplied to the gas nozzle is quantitatively and variably controlled by the gas flow rate control valve. Therefore, the average diameter of the bubbles generated in the liquid to be foamed,
The bubble size range is controlled.

[0013]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of a fine bubble generator according to the present invention. The fine bubble generator has a foaming action tank 1, and an ejector gas nozzle 3 is attached to the foaming action tank 1. In the foaming action tank 1, the liquid to be foamed A
The injection liquid B stored in the injection liquid tank 5 is injected from the ejector gas nozzle 3 into the tank. In many cases, this jet liquid B is
It may be the same liquid as the liquid to be foamed A in the foaming action tank 1.

A liquid overflow discharge pipe 7 is provided above the foaming action tank 1 in order to maintain the maximum liquid level in the tank, and an opening / closing valve 9 is provided in the middle of the liquid overflow discharge pipe 7. ing.
Further, a thermometer 11 for measuring the temperature in the foaming working tank 1 is attached.

A liquid pressure pump 13 is provided in the jet liquid tank 5. The liquid pumping pump 13 sucks the jetted liquid B in the jetted liquid tank 5 from a liquid pumping pipe 17 having a filter 15 attached to its lower end, pressurizes the sucked jetted liquid B, and pumps it to the liquid pumping pipe 19. The liquid pressure feed pipe 19 is connected to the ejector type gas nozzle 3, and a liquid flow rate control valve 21 and a flow meter 23 are attached on the way.

The liquid flow control valve 21 may be a variable flow control type normal flow control valve, which is manually operated or remotely operated by using an actuator, and is connected to the liquid pressure supply pipe 19.
The flow rate of the jetted liquid B flowing through is quantitatively controlled (in other words, variably set).

A liquid return pipe 25 for branching and returning the jetted liquid B to the jetted liquid tank 5 is connected to the liquid pumping pipe 19 on the ejector type gas nozzle 3 side of the liquid flow rate control valve 21. A liquid pressure control valve 27 is attached in the middle of the liquid return pipe 25.

As shown in FIG. 2, the liquid pressure control valve 27 includes a ball-shaped check valve body 35 biased in a valve casing 29 by a spring 31 toward a valve closing direction, that is, toward a valve seat 33. It is configured as a relief valve having, and establishes communication between the inlet port 37 and the outlet port 39 by opening the valve, and returns a part of the injection liquid B flowing through the liquid pressure supply pipe 19 to the injection liquid tank 5 by the liquid reflux pipe 25. The pressure of the ejected liquid B is reduced by the pressure. Check valve body 35
Is applied with the pressure of the injection liquid B of the liquid pressure feed pipe 19 in the valve opening direction from the inlet port 37, and is opened / closed by the equilibrium relationship between the valve opening force due to this pressure and the valve closing force due to the spring force of the spring 31. It has become.

The spring 31 is elastically mounted between a movable spring retainer 43 supported by an adjusting bolt 41 screwed into the valve casing 29 so that the screwing amount can be adjusted and a spring retainer 44 on the check valve body 35 side. The mounting preload is changed by adjusting the screwing amount of the retainer 43 into the valve casing 29, and the valve closing urging force of the check valve body 35, that is, the relief pressure of the liquid pressure control valve 27 is variably set. The variable setting range of this relief pressure is 5 to 2
It is set to about 5 kgf / cm ² .

A lock nut 45 is attached to the adjusting bolt 41 in order to maintain a stable screwing amount of the adjusting bolt 41 into the valve casing 29.

As shown in FIG. 1, the liquid pumping pipe 19
A thermometer 47 for measuring the temperature of the jet liquid B flowing through the liquid pressure feed pipe 19 and a pressure gauge 49 for measuring the pressure of the jet liquid B flowing through the liquid pressure feed pipe 19 are connected to the.

Further, the jet liquid tank 5 is provided with a thermometer 51 for measuring the temperature inside the bath, and a jet liquid supply pipe 53 for supplying the jet liquid B to the jet liquid tank 5 is provided. An on-off valve 55 is attached to the jet liquid supply pipe 53.

Next, the ejector type gas nozzle 3 will be described with reference to FIGS. The ejector type gas nozzle 3 has a nozzle body 57, and the nozzle body 57 is formed with a liquid passage 59 to which the liquid pressure-feeding pipe 19 is connected and to which the jetted liquid B is supplied. A liquid nozzle member 61 is removably fitted and attached to the tip side of the nozzle body 57, and a nozzle thin tube 65 is precisely attached to the tip of the liquid nozzle member 61 so as to project forward from the center of the tip surface of the nozzle body 57. It is fixedly attached by fitting. The liquid injection hole 63 formed in the nozzle thin tube 65 communicates with the liquid passage 59, is supplied with the injection liquid B from the liquid passage 59, and ejects it forward. Here, the nozzle thin tube 65
Is preferably 2 to 4 mm in total length, but the nozzle member 6
The optimum length is about 3 mm, with a fitting length of about 1.5 mm and a protruding length from the nozzle member 61 of about 1.5 mm. Further, the outer diameter d ₁ of the nozzle thin tube 65 is 0.6 to ₁ .
6 mm, inner diameter d ₂ , that is, the diameter of the liquid injection hole 63 is 0.3 to
It may be about 1.2 mm. The liquid nozzle member 61
The nozzle thin tube 65 may be formed integrally with the nozzle body 57 in order to reduce the number of parts.

A suction gas passage 67 is formed in the nozzle body 57, and the suction gas passage 67 is provided at one end thereof with the nipple 6.
It is connected to the gas suction pipe 71 by 9. A cylindrical outer case 73 having a nozzle mounting flange portion 72 is fitted and mounted in an airtight state by an O-ring 75 on the outer circumference of the cylindrical portion of the nozzle body 57. The suction gas passage 67 communicates at the other end with an annular passage 76 formed between the nozzle body 57 and the outer case 73. The annular passage 76 is formed around the liquid nozzle member mounting portion of the nozzle body 57 and communicates with each of the plurality of suction gas passages 77 that are open at the tip surface of the nozzle body 57.

A spacer ring 81 and a shim ring 83 for positioning the gas nozzle are provided on the outer periphery of the tip of the nozzle body 57.
However, an O-ring 79 is airtightly detachably fitted and mounted, and a cap-shaped gas nozzle member 85 is exchangeably fixedly mounted by screw engagement. A suction gas chamber 86, which is in communication with the suction gas passage 77, is formed between the tip surface of the nozzle body 57 and the gas nozzle member 85, and a nozzle thin tube 65 is provided at the center of the suction gas chamber 86. It extends across.

At the center of the tip of the gas nozzle member 85, a gas injection hole 87 is formed which opens from the suction gas chamber 86 to the tip surface of the gas nozzle member 85. The gas injection hole 87 is formed outside the nozzle thin tube 65 and concentric therewith, and the liquid injection hole 6 is formed.
The parallel passage portion 89 extends along the liquid ejection direction from the liquid ejection hole 63 at a position concentric with the axial center of the liquid ejection hole 63. The length L of the parallel passage portion 89 is set to about 1 to 6 mm,
Further, the inner diameter dg thereof may be set to about 0.8 to 2.0 mm.

The nozzle thin tube 65 is set by the above-mentioned dimension setting.
A gas ring layer is formed between the outer peripheral surface of the inner peripheral surface of the parallel passage portion 89 and the inner peripheral surface of the parallel passage portion 89. The thickness δg of this gas ring layer is (dg
-D ₁ ) / 2, which is 0.1 to 0.2 mm
It is set to the range of. Further, the relative position ΔL of the tip of the nozzle thin tube 65 to the starting end of the parallel passage portion 89 is set to about 0 to −6 mm, and this adjustment is performed by exchanging the shim rings 83 having different thicknesses (where ΔL is the parallel passage). The coordinate value of the tip of the nozzle thin tube 65 with respect to the starting end of the portion 89 is shown in FIG. 4, and when the nozzle thin tube 65 is inserted inside the parallel passage portion 89, it takes a positive value and becomes parallel. It takes a negative value when it is pulled out from the passage portion 89).

The dimensions of the above-mentioned respective parts of the ejector type gas nozzle 3 and the combination thereof are determined in consideration of the type of the ejected liquid B, the viscosity, the required foaming property and the like. Six types of specifications of the ejector type gas nozzle 3 corresponding to this are shown in Table 1, and examples of proper nozzle selection for the types of the ejected liquid B in these six types of ejector type gas nozzles are shown in Table 2. There is.

[0030]

[Table 1]

[0031]

[Table 2]

The above-mentioned gas suction pipe 71 is connected to a gas supply source of air, ozone, various kinds of inert gas or the like at the suction port so as to supply a desired gas to the suction gas passage 67 of the ejector type gas nozzle 3. It has become. Gas suction pipe 7
As shown in FIG. 1, a suction gas micro flow rate control valve 91 is connected to 1.

The suction gas minute flow rate control valve 91 is constituted by a flow rate control valve having a minute variable throttle such as a needle valve, and the like, and quantitatively variably controls the gas flow rate flowing through the gas suction pipe 71. In addition, 93 is a gas flow meter.

Next, the operation of the fine bubble generator having the above structure will be described.

When bubbles are generated, the liquid pressure pump 13
Is operated, whereby the ejection liquid B in the ejection liquid tank 5 is pressurized and pressure-fed to the liquid pressure-feeding pipe 19. The flow rate of the ejected liquid B is controlled by the liquid flow rate control valve 21. Further, the liquid pressure control valve 27 is opened according to the pressure of the ejected liquid B, whereby the excess ejected liquid B is returned to the ejected liquid tank 5 through the liquid recirculation pipe 25. Therefore, the pressure of the ejected liquid B in the liquid pressure supply pipe 19 is adjusted according to the relief pressure of the liquid pressure control valve 27.

As a result, the injection liquid B whose flow rate is controlled by the liquid flow rate control valve 21 and whose pressure is adjusted by the liquid pressure control valve 27 is pressure-fed to the liquid passage 59 of the ejector type gas nozzle 3. Therefore, the flow rate of the injection liquid B supplied to the liquid passage 59 of the ejector gas nozzle 3 is quantitatively and variably set according to the flow rate setting value of the liquid flow rate control valve 21, and the pressure of the injection liquid B is set to the liquid pressure control valve. It is variably set quantitatively according to the set relief pressure of 27.

The jet liquid B supplied to the liquid passage 59 of the ejector type gas nozzle 3 passes through the inside of the liquid nozzle member 61 and is jetted at high speed from the liquid jet hole 63 of the nozzle thin tube 65 toward the gas jet hole 87. Negative pressure is generated in the outer peripheral portion of the jet flux of the jet liquid B in accordance with the jet flow velocity of the jet liquid B, whereby the gas (gas) in the suction gas chamber 86 runs along the outer peripheral portion of the jet flux of the jet liquid B. Is sucked into the parallel passage portion 89 of the gas injection hole 87, and is sheared by the jet flow of the jet liquid B to form fine bubbles that are jetted together with the jet liquid B into the foaming liquid A in the foaming action tank 1.

Here, in this embodiment, since the total length of the nozzle thin tube 65 is as short as 2 to 4 mm, it is easy to align the axial center of the tip portion of the nozzle thin tube 65 with the gas injection hole 87. I can do it. Therefore, the interval | ΔL | of the nozzle thin tube 65 with respect to the gas nozzle 85.
Even if (| ... | is an absolute value symbol) increases, the axial center error between the liquid nozzle and the gas nozzle does not become larger than a predetermined value, and stable ultrafine bubbles can be generated. As a result, fine bubbles can be generated with high efficiency (because increasing the interval | ΔL | improves bubble generation efficiency).

Further, since the total length of the thin tube 65 is short, the liquid ejection speed can be easily increased, and the bubble diameter can be further miniaturized (see FIG. 7 and the description below).

FIG. 5 schematically shows the results of microscopic observation of the mechanism of bubble generation as described above using an ejector gas nozzle for visualization experiments having the same structure as the ejector gas nozzle 3 described above, and observation by ultra-high-speed photography. ing. As shown in this schematic diagram, the outer diameter d _{1 of the} nozzle thin tube 65
However, 0.6 to 1.6 mm, preferably 0.6 to 1.2 m
m, the inner diameter dg of the parallel passage portion 89 of the gas injection hole 87 is 0.8
~ 2.0 mm, preferably 0.8-1.4 mm, the length L of the parallel passage portion 89 is 1-6 mm, preferably 3-4 mm
The basic structure of the fluid flow in the negative pressure part of the gas nozzle, which is composed of a minute space, is that the liquid injection hole 6 as the driving flow is used.
The jet flow Bj of the jetted liquid B from 3 and the foamed liquid laminar flow As that enters the gas injection hole 87 from the foaming action tank 1 and adheres to the inner wall surface of the parallel passage portion 89 thereof are sandwiched between them. It is constituted by a suction gas flow Gi as a secondary flow that surrounds the jet flow Bj of the jet liquid B and has a tapered triangular cross section as it goes forward in the jet direction of the jet liquid B.

In this case, the suction gas adheres to the inner wall surface of the parallel passage portion 89 and the jet Bj of the jet liquid B ejected from the tip of the nozzle thin tube 65 toward the parallel passage portion 89 of the gas injection hole 87. It is in a state of being sandwiched between the foamed liquid laminar flow As. Then, due to the action of the viscous force acting between the surface of the jet Bj of the jet liquid B and the gas surrounding the jet Bj, the jet B of the jet liquid B having a tapered triangular cross section.
It is dragged into the gas injection hole 87 as a suction gas flow Gi that surrounds and surrounds j. Then, in the peripheral portion of the contact between the suction gas flow Gi and the jet Bj of the jet liquid B indicated by the symbol C, the relative movement of the jet Bj of the jet liquid B and the suction gas flow Gi causes the suction gas flow Gi to move. Fine bubbles Gb are generated by shearing the gas.

In the fine bubble generator using the ejector type gas nozzle 3, the factors affecting the foaming performance are the liquid nozzle, that is, the jet speed VL of the jet liquid B from the liquid jet hole 63, the gas jet hole. 87, the length L of the parallel passage portion 89, the relative position ΔL of the tip of the nozzle thin tube 65 to the starting end of the parallel passage portion 89, the gas ring thickness δg, and the outer diameter d of the nozzle thin tube 65.
₁ , physical properties such as inner diameter d ₂ , kinematic viscosity of the jetted liquid B, surface tension, density and the like.

Of these, the factor that has the greatest effect on the foaming performance is the jet speed VL of the jet liquid B from the liquid jet hole 63.

The jet speed VL of the jet liquid B from the liquid jet hole 63 is determined by the pressure of the jet liquid B at the inlet of the liquid jet hole 63, and the higher this pressure, the faster the jet speed VL. Therefore, it can be understood that the magnitude of the jetting speed VL of the jetted liquid B is equal to the magnitude of the pressure of the jetted liquid B at the inlet of the liquid jet hole 63.

The pressure of the jetted liquid B at the inlet of the liquid jet hole 63 is quantitatively variably set by the flow rate set value of the liquid flow rate control valve 21 and the set relief pressure of the liquid pressure control valve 27. As a result, the ejection speed VL of the ejection liquid B is 20 to 5
It is variably controlled in the range of 0 m / s, and the foaming performance, that is, the amount of bubbles generated in the liquid A to be foamed, the average bubble diameter, and the bubble diameter range are variably controlled.

In FIG. 6, the nozzle type name in Table 1 is LN.
6 and LN8 nozzles, water at 20 ° C. is jetted as liquid B from the liquid jet hole 63 at the jet speed VL, and the relationship between the jet speed VL and the suction gas flow rate Qg and the suction gas flow rate Qg and the liquid It is an experimental result showing a ratio with the fluid ejection flow rate QL from the injection hole 63, that is, a flow rate ratio ζ = (Qg / QL) × 100%.

In this case, for example, in the case where the nozzle type name is LN8, when the ejection velocity VL is around 40 m / s, the suction gas flow rate Qg becomes about 900 ml / min.
The suction gas flow rate Qg is about 2.
It becomes four times, and the gas due to this suction gas flow rate Qg becomes fine bubbles to be foamed in the foamed liquid A.

The flow rate ratio ζ = (Qg / QL) × 100%
Varies depending on the types of the ejected liquid B and the suction gas, and the physical properties of the ejected liquid B, particularly the surface tension, have a great influence. The maximum value of the flow rate ratio ζ is about 230% for water and about 50 for tamarind aqueous solution.
%, About 30% with salad oil.

7 and 8 show a bubble diameter distribution state when fine bubbles are generated in a liquid by the fine bubble generating device as described above.

Among these, FIG. 7 shows that, using the nozzle of nozzle type name LN6 in Table 1, the ejection speed VL of the liquid from the liquid injection hole 63 into the salad oil having a kinematic viscosity of 40 μm ² / s.
Respectively as 20 m / s, 25 m / s, 30 m / s,
Spouting speed V when salad oil is spouted continuously for 40 seconds
These are the experimental results showing the effect of L on the bubble size distribution. The bubble diameter and the number of generated bubbles in this experimental result are obtained by the following method. That is, first 10 × 10 m
It was generated in a volume of 0.2 ml of salad oil between a m ² blue acrylic resin plate bubble diameter / bubble number density measuring plate and a transparent acrylic resin foaming action tank facing it at 2 mm intervals. Take a picture of the bubbles from three places.
Then, this is stretch-developed on a printing paper, and the total number of bubbles and the number of individual bubble diameters are counted by a loupe with a scale.

As shown in FIG. 7, as the jetting speed VL of the salad oil increases, the maximum bubble diameter is reduced, and the bubble diameter distribution shifts to the smaller diameter side. In all cases, 90% or more of the total number of bubbles have a diameter of 200μ.
m or less, the average bubble diameter ADg is 136 to 141 μm
And very small.

In FIG. 8, the ejection velocity VL of the liquid from the liquid ejection hole 63 is constant at 30 m / s, and the liquid ejection hole is changed to one of the nozzle type names LN8, LN10 and LN12 in Table 1. ² is an experimental result when a highly viscous tamarind aqueous solution having a kinematic viscosity of 1600 μm ² / s was jetted into a tamarind aqueous solution having the same kinematic viscosity. Observation and counting of the bubble diameter and the number of generated bubbles in this experimental result were performed in the same manner as that in FIG. 7.

In this case, the generation rate of small-sized bubbles increases as the nozzle diameter of the liquid injection hole increases, and the average bubble diameter ADg also decreases accordingly.

The ejection velocity V of the liquid from the liquid ejection hole 63
An experiment was conducted to determine which of the physical property values (that is, kinematic viscosity, surface tension, and density) of the ejected liquid has a great influence on the foaming performance, with L kept constant at 30 m / s. As a result, it was found that the magnitude of the kinematic viscosity and the density had little influence on the foaming performance, and the factor having a great influence on the foaming performance was the surface tension showing the relationship with temperature in FIG.

In the experiment in which the liquid temperature was 20 ° C.,
When the salad oil having a kinematic viscosity of 400 μm ² / s is set to 1, the suction air flow rate Qg sucked into the negative pressure portion of the parallel passage portion 89 of the gas injection hole 87 is 1600 μm ² / s in a tamarind gum aqueous solution. A water viscosity of about 3 and a kinematic viscosity of 1 μm ² / s gave a result of 6-9. From this, it was found that the influence of the surface tension of the liquid on the foaming performance was very large.

The foaming distribution ratio by foam diameter when foamed in the salad oil of FIG. 7 and the tamarind aqueous solution of FIG. 8 is determined by the liquid injection hole 63 with the suction gas micro flow rate control valve 91 fully opened. 2 shows the result of an experiment performed by adjusting the opening of the liquid flow rate control valve 21 and the relief pressure of the liquid pressure control valve 27 so that the liquid ejection speed VL from the above-mentioned becomes a predetermined value. The average bubble diameter of the bubbles generated in this experiment is
In the case of salad oil, it is about 130 to 140 μm, whereas in the case of tamarind aqueous solution, it is about 240 to 280 μm.
That's almost twice as big as salad oil. The reason for this is as follows. That is, in the case of salad oil, the surface tension is small and the suction gas flow rate Qg is small (the liquid ejection speed VL is 40
In the case where the liquid jet speed VL is within the range of 20 to 30 m / s, the jet speed becomes 0 when the liquid jet speed VL is in the range of 20 to 30 m / s. Almost no coalescence growth phenomenon of bubbles. On the other hand, in the case of the tamarind aqueous solution, bubble growth occurs due to the turbulent flow at the tip of the jet. Furthermore, in the case of an aqueous solution of tamarind, since the kinematic viscosity of the liquid is very high at 1600 μm ² / s, the rise and dissipation phenomenon of the growing bubbles is small, and the coalescing growing bubbles are trapped in the liquid for a long time. Is easy. For this reason, the average bubble diameter of bubbles in the tamarind aqueous solution is large.

In the case of water, the foaming distribution ratio by bubble diameter is
It is difficult to measure. Because the surface tension is larger than that of other liquids, the suction gas flow rate Qg, that is, the number of foaming bubbles is very large, and the kinematic viscosity is very small, 1 μm ² / s. Moves fast.
At the tip of the collision where the velocity of the jet flow is zero, the ultrafine bubbles that have reached this point collide in this turbulent flow and coalesce into growth bubbles to increase the diameter. This large bubble rises faster than other fine bubbles and dissipates into the atmosphere, and the number of bubbles generated cannot be accurately measured by camera photography.

In summary, the ejection velocity VL of the liquid from the liquid ejection hole 63 is determined by the physical property value of the ejected liquid, that is, the kinematic viscosity,
It is set to an appropriate value according to the surface tension and density. For example,
As shown in Table 2, in case of low viscosity liquid such as water, 3
It is set to 0 m / s or more, 20 m / s or more for medium viscosity liquids such as egg white, yolk liquid, and edible oil, and 25 m / s or more for high viscosity liquids such as dissolved chocolate, fresh cream liquid, paints, etc. It

According to this, the pressure of the jetted liquid B at the inlet of the liquid jet hole 63, which determines the jetting speed VL of the liquid, in other words, the relief pressure of the liquid pressure control valve 27 is a low to medium viscous liquid. It is set to 6 to 15 kgf / cm @ 2, and for high viscosity liquid it is set to 10 to 20 kgf / cm @ 2.

The size of the total amount of bubbles generated in the liquid A to be foamed may be, for example, a group of ultrafine bubbles having a size of 100 μm or less, or the number of bubbles generated may be small, but the bubble diameter is further reduced. Or, if you want to minimize the generation of growth bubbles due to collisional coalescence of ultrafine bubbles at the jet reaching tip, to generate only ultrafine bubbles, that is, a control method for controlling the generated bubble diameter will be described below. ..

In the standard control method, first, the opening degrees of the liquid flow rate control valve 21 and the suction gas micro flow rate control valve 91 are controlled in relation to each other.

In this case, first, the suction gas micro flow rate control valve 9
1 is fully opened, the opening degree of the liquid flow rate control valve 21 is adjusted, and the gas flow rate Qg sucked through the gas suction pipe 71 to the negative pressure portion in the parallel passage portion 89 of the gas injection hole 87, that is, The amount of ultrafine bubbles generated in the foaming liquid A is maximized. And so that this foaming state is continuously and stably performed,
The spring force of the liquid pressure control valve 27, that is, the relief pressure is adjusted.

Next, in the turbulent flow of the arrival tip of the liquid jet ejected into the liquid A to be foamed, the degree of opening of the suction gas micro flow control valve 91 eliminates the coalescence growth phenomenon of bubbles due to collision of fine bubbles. Fine-tune until.

As a result, in particular, as the opening degree of the suction gas flow rate control valve 91 is made smaller, smaller fine bubbles can be generated.

The control operation according to the above-mentioned procedure is based on the standard control method, but apart from this, even if the number of generated bubbles is sacrificed to some extent, the average bubble diameter of the generated bubble group is determined to be a haze foaming state in water. In some cases, it may be desired to set the diameter of fine bubbles to 50 μm to 60 μm. In such a case, in addition to adjusting the opening degree of the liquid flow rate control valve 21 and the relief pressure of the liquid pressure control valve 27, the opening degree of the suction gas micro flow rate control valve 91 is adjusted. The latter limits the gas flow rate Qg sucked by the negative pressure portion in the parallel passage portion 89 through the gas suction pipe 71. In this case, the opening of the liquid flow control valve 21 and the liquid pressure control valve 27
The relief pressure and the opening degree of the suction gas micro flow rate control valve 91 are adjusted in association with each other. That is, in this case, first, the opening amount of the liquid flow rate control valve 21 and the relief pressure of the liquid pressure control valve 27 are adjusted to each other to monitor the foaming state in the liquid A to be foamed and determine the foaming amount to be appropriate. After confirming that the bubbles are stably and continuously generated, the opening degree of the suction gas minute flow rate control valve 91 is finely adjusted to realize the required haze foaming. Also in this case, smaller fine bubbles can be generated as the opening degree of the suction gas flow rate control valve 91 is reduced. More specifically, the gas flow rate Q is controlled by the suction gas micro flow rate control valve 91.
When g is squeezed to about 1/2 of the value when fully opened, the bubble diameter becomes 100.
Ultra-fine bubbles of μm or less are generated, and when the gas flow rate Qg is reduced to about ⅓ of the fully opened state, ultra-fine fumed bubbles floating in water are generated.

When the number of generated bubbles (number density) is insufficient in ultra-fine generation and it is desired to increase the number of generated bubbles, the number of ejector gas nozzles 3 mounted in the foaming action tank 1 should be plural. It is sufficient to increase the number to the number of bubbles, which allows the desired amount of bubbles to be freely obtained.

The present invention is useful not only as a means for containing fine air bubbles in a food as described above, but also as a foaming means in other fields as described below.

(1) When water containing a large amount of ultrafine bubbles was given to a young piglet with a shallow birth, the peripheral nerves of the digestive system were activated,
It improves digestion and absorption of feed and promotes fattening of young pigs. The ultrafine bubble generator of the present invention is useful in this regard.

(2) Since ultrafine bubbles have a large contact area with water, they have a large effect of increasing dissolved oxygen in water. Therefore, ultrafine bubbles are useful for supplementing oxygen to freshwater and saltwater fish culture ponds and water bodies. In particular, the ultrafine air bubble generator of the present invention is capable of continuously and stably producing a large amount of ultrafine air bubbles of 10 to 200 μm, and is therefore optimal for increasing dissolved oxygen.

(3) Aerated confectionery such as whipped cream, ice cream and light snow can improves the sensory function of the food such as improving the texture of the food and taste. Also,
When the air bubbles are not air but an inert gas such as CO ₂ or N ₂ gas and an aroma component is contained therein, effects such as prevention of food deterioration and imparting aroma are brought about. The ultrafine bubble generator of the present invention is useful in this regard.

(4) Since the ultrafine bubbles have a large contact surface area with water, this improves the dissolution of O ₂ or O ₃ gas in water, that is, the gas-liquid reaction efficiency. In particular, in the production of ozone water having a large deodorizing, decolorizing and bactericidal effect, the ultra-fine bubbles in the form of fumes in the water produced by the ultra-fine bubble generator of the present invention efficiently produce 1 to 3 ppm of ozone water. Useful above.

(5) Since the ultrafine bubble generator of the present invention is capable of continuously and stably producing a large amount of ultrafine bubbles of several μm to several 100 μm, most of them generate only fine bubbles of about 1 to 5 mm. The bubble reaction during the chemical substance manufacturing process can be performed more efficiently than the conventional fine bubble generator that cannot do so.

(6) The above (2), (3) and (5) are useful for human waste purification treatment in pig farms, cattle farms and the like.

(7) The ultrafine bubble generating apparatus of the present invention is useful for coating a bubble-containing thin film urethane film on the surface of a raw leather to conceal and make beautiful the surface of the raw leather such as an automobile seat and a leather seating chair set for reception. The coating on the leather surface does not contain air bubbles,
Although the leather "burrs" and loses its flexibility, the aerated leather coated with a paint containing bubbles of several tens to 100 µm or less does not lose the flexibility of the tanned leather.

In this regard, an acrylic paint having a kinematic viscosity of 12 μm ² / s is used, using the ultrafine bubble generator of the present invention,
The same paint was mixed in urethane paint with a very high viscosity of 2000 μm ² / s, and the nozzle type name in Table 1 was LN8 (liquid nozzle inner diameter d 2 = 0.5 mm).
N10 (liquid nozzle inner diameter d2 = 0.65 mm) liquid nozzle is used and the ejector gas nozzle inlet pressure is 20 k
It was sprayed as g / cm ² to generate ultrafine bubbles, which were coated using a special roll for bubble-containing coating.
We have succeeded in coating a bubble-containing thin film urethane coating containing a large amount of bubbles of 0-100 μm or less.

In the above, the present invention has been described in detail with respect to a specific embodiment, but the present invention is not limited to this, and various embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art.

[0077]

As can be understood from the above description, according to the fine bubble generating method and the fine bubble generating apparatus of the present invention, the flow rate of the gas supplied to the gas nozzle is quantitatively and variably controlled by the gas flow rate control valve. Since the average diameter of the bubbles generated in the foamed liquid and the bubble diameter range are controlled, the average diameter of the generated bubbles and the bubble diameter range can be variably set to appropriate values according to various requirements.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a fine bubble generator according to the present invention.

FIG. 2 is a vertical cross-sectional view showing an embodiment of a liquid pressure control valve used in the fine bubble generator according to the present invention.

FIG. 3 is a vertical cross-sectional view showing an embodiment of an ejector type gas nozzle used in the fine bubble generator according to the present invention.

FIG. 4 is an enlarged vertical cross-sectional view of a nozzle hole portion of an ejector type gas nozzle used in the fine bubble generator according to the present invention.

FIG. 5 is an explanatory view schematically showing a mechanism of bubble generation by air in the fine bubble generator according to the present invention.

FIG. 6 shows the relationship between the ejection speed and the suction gas flow rate when water is ejected from the liquid injection hole as liquid by using liquid nozzles of various sizes, and the suction gas flow rate and the water ejection flow rate ratio from the liquid injection hole. It is a graph shown.

FIG. 7 is a graph showing, in a bubble diameter distribution state, the effect of the jet speed on the bubble diameter distribution when the salad oil from the liquid injection holes is jetted into the salad oil by changing the jet speed.

FIG. 8 is a graph showing, in a bubble diameter distribution state, the influence of the nozzle dimension on the bubble diameter distribution when the tamarind aqueous solution is ejected from the liquid injection hole into the tamarind aqueous solution from a liquid nozzle nozzle of various sizes.

FIG. 9 is a graph showing the relationship between the surface tension of various liquids and the temperature.

[Explanation of symbols]

 1 Foaming Action Tank 3 Ejector Gas Nozzle 13 Liquid Pressure Pump 21 Liquid Flow Control Valve 27 Liquid Pressure Control Valve 57 Nozzle Body 61 Liquid Nozzle Member 63 Liquid Injection Hole 65 Nozzle Capillary 73 Outer Case 85 Gas Nozzle Member 86 Suction Gas Chamber 87 Gas Injection Hole 89 Parallel passage 91 Micro flow control valve

Claims (11)

[Claims] 1. An ejector-type gas nozzle having a liquid nozzle and a gas nozzle is used, a liquid is ejected from the liquid nozzle into a liquid to be foamed, and a gas from the gas nozzle is foamed by a negative pressure generated by a jet flow of the liquid. A method of generating fine bubbles which is sucked into a liquid to generate fine bubbles in the liquid to be foamed, wherein fine bubbles are generated by limiting gas supply to the gas nozzle. 2. An ejector-type gas nozzle having a liquid nozzle and a gas nozzle is used, a liquid is jetted from the liquid nozzle into the liquid to be foamed, and the negative gas generated by the jet flow of the liquid causes the foamed gas from the gas nozzle to be foamed. A method for generating fine bubbles that is sucked into a liquid to generate fine bubbles in the liquid to be foamed, and a fine bubble diameter of the fine bubble to be generated in the liquid to be foamed is variably controlled by controlling the flow rate of the gas supplied to the gas nozzle. A method for producing fine bubbles, characterized by controlling the size. 3. The method for generating fine bubbles according to claim 2, wherein the flow rate and the pressure of the liquid supplied to the liquid nozzle are variably controlled in accordance with the control of the gas flow rate. 4. The quantitative control range of the pressure of the liquid supplied to the liquid nozzle is set to 5 to 25 kgf / cm ^2, and the ejection speed of the liquid ejected from the liquid nozzle into the foaming liquid by the pressure control is 20 to 20 kgf / cm ^2. The method for generating fine bubbles according to claim 1 or 2, wherein the setting is variably set within a range of 50 m / s. 5. An ejector type gas nozzle having a liquid nozzle and a gas nozzle is provided, wherein the liquid nozzle ejects a liquid into the liquid to be foamed, and a negative pressure generated by the jet flow of the liquid causes the gas nozzle to cover the gas. A liquid bubble flow control valve for quantitatively controlling the flow rate of the liquid supplied to the liquid nozzle, which is a fine bubble generator that is sucked into the foaming liquid to generate fine bubbles in the liquid to be foamed. A liquid bubble control valve for quantitatively controlling the pressure of the liquid to be supplied, and a gas flow rate control valve for quantitatively controlling the flow rate of the gas to be supplied to the gas nozzle. apparatus. 6. The fine bubble generator according to claim 5, wherein the liquid pressure control valve is a relief valve in which the relief pressure is quantitatively and variably set. 7. The gas nozzle is provided outside the liquid nozzle concentrically with the liquid nozzle, and is provided with a parallel passage portion extending along a liquid ejection direction from the liquid nozzle. The fine bubble generator according to any one of 1 to 6. 8. The fine bubble generator according to claim 7, wherein the parallel passage portion of the gas nozzle has a length of 1 to 6 mm. 9. The inner diameter of the liquid nozzle is 0.3 to 1.2.
mm, the inner diameter of the gas nozzle is 0.8 to 2.0 mm, and the thickness of the gas ring formed between the outer peripheral portion of the liquid nozzle and the gas nozzle portion is 0.1 to 0.2 mm. The fine bubble generator according to claim 7 or 9. 10. The fine bubble generator according to claim 7, wherein a gap between the tip of the liquid nozzle and the start of the parallel passage portion of the gas nozzle is 0 to 6 mm. 11. An ejector-type gas nozzle having a liquid nozzle and a gas nozzle, wherein the liquid nozzle ejects a liquid into a liquid to be foamed, and a negative pressure caused by a jet flow of the liquid causes the gas nozzle to cover the gas. A fine bubble generator for sucking into a foaming liquid to generate fine bubbles in the liquid to be foamed, wherein a total length of a nozzle thin tube of a liquid nozzle is 2 to 4 mm.