JP2002191950A - Fine air bubble generator using special nozzle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a uniform fine air bubble generator which produces uniform fine air bubbles and has a high energy efficiency. SOLUTION: A gas nozzle for discharging a gas is arranged at the central part and a group of nozzles consisting of a plurality of liquid nozzles for jetting a liquid is arranged on the surrounding part of it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microbubble generator for generating microbubbles uniformly.

[0002] In the field of the chemical industry, it is necessary to generate microbubbles to promote a chemical reaction or to increase the surface area of bubbles when a gas is absorbed in a liquid.

The present invention contributes to improving the efficiency of a liquid-phase chemical reaction system and a gas absorption system in the field of chemical engineering.

[0004]

2. Description of the Related Art As a conventional technique for generating bubbles, there are a method of ejecting gas from a nozzle, a method of entraining gas by a wave on a liquid surface, a method of utilizing cavitation, and a method of blowing gas into a high-speed liquid flow.

[0005]

In the method using a nozzle, control of the bubble diameter is easy. However, since a nozzle of about 100 μm is required for generating bubbles of 1 mm or less, it is difficult to process the nozzle for generating minute bubbles, and it is inefficient for generating a large amount of bubbles,
The problem is that the maintenance is troublesome. In the method using gas entrainment on the liquid surface and high-speed liquid flow, it is difficult to control the bubble diameter and suppress the generation of large-diameter bubbles. In addition, generation by cavitation generally has a drawback that generation efficiency with respect to input energy is low. For these reasons, development of a generator that can generate uniform microbubbles and has high energy efficiency is desired here. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a uniform microbubble generator capable of generating uniform microbubbles and having high energy efficiency.

[0006]

In response to this object, a microbubble generator according to the present invention has a gas nozzle for discharging gas at a central portion and a plurality of liquid nozzles for discharging liquid at a peripheral portion. It is characterized in that a nozzle group is arranged.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings showing an embodiment. 1 and 2, reference numeral 1 denotes a microbubble generator. The microbubble generator 1 includes a gas nozzle 2 for discharging gas and a liquid nozzle group 4 including a plurality of liquid nozzles 3 for discharging liquid.

One or a plurality of gas nozzles 2 are arranged at the center of the microbubble generator 1 and have a diameter of, for example, 0.1 to 10 mmφ and a length of 1 to 100 mm.
0 mm. The number of the liquid nozzles 3 in the liquid nozzle group 4 is, for example, three or more (eight in the case of this embodiment), and the liquid nozzles 3 are arranged on a circle of 0.5 to 10 mmφ around the gas nozzle 2. The diameter of the liquid nozzle 3 is, for example, 0.01 to 10
mmφ. The flow velocity of the gas discharged from the gas nozzle 2 is smaller than the flow velocity of the liquid discharged from the liquid nozzle group 4, for example, the former is 10 ml / min to 100 ml / mi.
n, the latter being from 20 ml / min to 1000 ml / m
in.

[0009] The microbubble generator 1 configured as described above.
When the microbubbles are generated by using the microbubbles, the microbubble generator 1 is immersed in the liquid, the gas is discharged from the gas nozzles 2, and the liquid is discharged from the liquid nozzle group 4. The discharged gas is crushed by the liquid discharged from the surroundings,
Micro bubbles are generated in the liquid.

[0010]

[Experimental Example] In this study, the study focused on a circular tube group nozzle manufactured by bonding circular tubes having a nozzle outlet sectional shape as shown in FIG. Since the nozzles are all made of stainless steel and the minimum pore size used in this experiment is 500 μm,
The production is very easy regardless of the processing method. The tube group is
It is composed of a central nozzle having a diameter of 1.0 mm and a length of 80 mm, and eight peripheral nozzles having a diameter of 0.5 mm and a length of 10 mm. The central part and the peripheral part are connected to different supply ports, and the same fluid is ejected from the eight peripheral parts at the same flow rate. This nozzle is (w) 600 × (d) 400 ×
(H) fixed to the center of the lower part of a 600 mm acrylic water tank,
An experiment was performed. As the supply fluid, air was used for the gas phase, and filtered tap water was used for the liquid phase. Bubble group bubble diameter distribution measurement Sub-millimeter microbubbles have a very small inertia and easily follow the carrier fluid, making it difficult to accurately detect them with a contact sensor such as a point electrode probe. Therefore, it is more important to introduce a non-contact measurement method than when measuring a large-diameter bubble. In this experiment, an image processing method was adopted. The camera used was a CMD digital high-speed camera (NAC, Memorycam Ci) equipped with a high-speed shutter.
The spatial resolution of this camera is 572 × 432 pixels, the luminance resolution is 8 bits in the monochrome mode, and the maximum sample rate under this condition is 500 images / s. Photographing was performed using forward scattered light with the light source, aquarium, and camera arranged so as to be aligned. A halogen lamp was used as a light source.
Tracing paper was inserted as a diffusion plate on the surface of the water tank on the light source side to make a pseudo diffusion light source. In this configuration,
Bubbles are recorded in the camera as sharp "shadows", which improves the accuracy of particle size measurements compared to side scatter and forward scatter. The photography was performed in the black and white mode.

The bubble image obtained by the high-speed camera is an uncompressed 8-bit magnetic medium (Iomeg).
a, Jaz Drive), and is converted into a general-purpose image format by a computer after photographing is completed. The bubble diameter can be calculated using software on a computer, such as background processing, noise removal, binarization, spot removal at the center of the bubble, labeling, calculation of bubble position and area equivalent diameter, edge detection of bubbles, detection of overlapping bubble images, The calculation was performed by continuously performing the process of calculating the bubble diameter. Note that the image processing is performed in two types of procedures depending on whether or not the bubbles are deformed.

The particle size distribution and statistics under each experimental condition are 10
The calculation was performed using data of 1,000 or more bubbles from which about 30 images were obtained. The processing time is usually 1-2 minutes when the cross-correlation calculation is performed, and about 10 seconds when the cross-correlation calculation is not performed, and the batch processing is performed automatically. In the experiment, two types of water and air outlets were exchanged. As a result of the visualization experiment, many small bubbles were observed when air was blown out from the center. The following results were obtained from the visualized image when the flow rate QA of the primary flow air was kept at 20 ml / min and the flow rate QW of the secondary flow water was changed. When the water flow rate QW is 0, the generated bubble diameter is about 4 mm, the bubble interval is always constant, and the bubble supply amount is stable. When QW was increased to 100 ml / min, bubbles were greatly diffused due to turbulence of the liquid phase, and generation of slight microbubbles was confirmed, but the size of most of the bubbles was hardly changed. Further increase the flow rate of water, 3
When the flow rate reaches 00 ml / min, the flow pattern changes drastically, and a large amount of microbubbles is generated. QW = 500 where the Reynolds number completely exceeds the transition Reynolds number
At ml / min, bubbles of the order of 1 mm disappeared completely, and no significant change in the flow pattern was observed thereafter even if the flow rate of water was increased.

FIG. 4 shows the particle size distribution when the air flow rate is 20 ml / min. When the flow rate of water was 0, the bubble diameter was almost uniform and was about 4 mm. Under these conditions, no microbubbles are generated. When the water flow rate is increased to 300 ml / min, the average particle diameter sharply decreases, and the distribution changes to a shape having a peak at a small particle diameter. When the flow rate of water is further increased, the distribution shifts to a smaller grain system side, and QW = 90
At 0 ml / min, the maximum particle size decreases to 600 μm. The smallest average particle size among the measurements in this experiment is that QA = 10 ml / m at which the flow rate ratio between water and air is maximum.
When in and QW = 900 ml / min, 99% was 500 μm or less and 78% was 200 μm or less in terms of the number. In this condition, because air intermittently blows out,
A more stable particle size distribution almost equal to QA = 20 ml / min was obtained.

QA = 20 ml / min, QW = 900 m
Sauter mean diameter at 1 / min is about 300 μm
Met. If air is simply blown out from a nozzle into stationary water, the buoyancy decreases sharply as the diameter decreases. To achieve the same Sauter average diameter, at least about 100 pipes with a diameter on the order of several μm are required. Need and not very realistic. From this, it can be said that the effect of promoting the atomization of the tube group nozzle is great.

[0015]

As is apparent from the above description, according to the present invention, it is possible to obtain a microbubble generating device which can generate uniform bubbles and has a high energy effect.

[0016]

[Brief description of the drawings]

FIG. 1 is an explanatory perspective view of a microbubble generator.

FIG. 2 is an explanatory cross-sectional view of the microbubble generator.

FIG. 3 is a sectional view showing a circular tube group nozzle.

FIG. 4 is a graph showing the particle size distribution of bubbles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microbubble generator 2 Gas nozzle 3 Liquid nozzle 4 Liquid nozzle group

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoichiro Matsumoto 1-42-20-302 Hayamiya, Nerima-ku, Tokyo (72) Inventor Fumio Takemura 1-2-2 Namiki, Tsukuba, Ibaraki Pref. (72) Inventor Mashan Labha F-term in the New Energy and Industrial Technology Development Organization 3-1-1 Higashiikebukuro, Toshima-ku, Tokyo 4G035 AB04 AC15 AE13

Claims (2)

[Claims] 1. A microbubble generating apparatus comprising: a gas nozzle for discharging a gas at a central portion; and a nozzle group including a plurality of liquid nozzles for discharging a liquid at a peripheral portion. 2. The microbubble generator according to claim 1, wherein the discharge speed from the nozzle group is higher than the discharge speed from the gas blowing nozzle.