JPS6268531A - Method for dissolving gas - Google Patents

Abstract

PURPOSE:To efficiently dissolve gas in a liquid, by injecting gas into the liquid from the specific gas diffusion member provided to the bottom part of a gas dissolving tank and holding gas bubbles below multistage porous laminar materials provided above said gas diffusion member in a film-like state to contact the same with the liquid. CONSTITUTION:Gas diffusion pipes 2 each provided with a large number of perforations each having a diameter of 1-3mm are provided to the bottom part of a gas dissolving tank 1 having a liquid received therein, and porous laminar materials 4 are arranged above said diffusion pipes 2 in a multistage fashion. Relatively large gas bubbles generated from the gas diffusion pipes 2 rise to be temporarily held to the porous laminar materials 4. Because each porous laminar material 4 has fine perforations capable of permitting the passage of fine gas bubbles, gas bubbles are gradually collected to form a gas film A and, when said gas film A reaches a definite thickness, equilibrium is lost to generate gas bubbles all together from the porous laminar materials 4 and rise to the upper stage. However, a part of gas bubbles remain on the under surface of each porous laminar material 4 and the gas film A is always formed to be always contacted with the liquid over a wide area on the upper and lower surfaces of each porous laminar material 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas dissolving method for efficiently dissolving gases such as oxygen and ozone into liquids such as tap water or sewage.

[Conventional technology]

Conventional gas dissolution methods involve ejecting the gas to be dissolved into the liquid as fine bubbles, as seen in the dissolution of ozone into tap water and the dissolution of oxygen into sewage during activated sludge treatment. It's just that it's being done.

[Problems to be solved by the invention]

However, these methods require a large amount of energy to make the bubbles fine, and the bubbles usually rise to a depth of 4 meters in about 10 seconds, so in order to increase the gas-liquid contact efficiency, it is necessary to generate bubbles constantly. However, there was a drawback that a large amount of energy was required to generate all of this large amount of bubbles.

[Means for solving problems]

In view of the current situation, the present invention has been developed by ejecting gas as bubbles from an aeration member having holes with a diameter of 1 to 3 m provided at the bottom of a gas dissolving tank filled with a liquid in which all gas is to be dissolved. The entire feature is that air bubbles are held in the form of a film below each porous layered material in a multi-stage porous layered material having pores provided above, and brought into contact with a liquid.

[Effect]

In the present invention, gas bubbles are ejected into the liquid from a relatively simple aeration member having holes with a diameter of 1 to 3+ mm provided at the bottom of the gas dissolving tank, so that bubbles can be generated with relatively small energy. Moreover, the air bubbles rising from the air diffuser are held in the multi-stage gas film by the porous layered material provided in multiple stages, so that a gas film is constantly formed at the bottom of the porous layered material. Since both the upper and lower surfaces are constantly in contact with the liquid, it is possible to obtain high dissolution efficiency with a smaller amount of gas supplied than in the conventional method in which all microbubbles are generated.

〔Example〕

Hereinafter, the present invention will be explained in detail according to examples.

In the figure, reference numeral 1 denotes a gas dissolving tank containing a liquid in which gas is to be dissolved, and the bottom of the gas dissolving tank 1 is equipped with an aeration pipe 2, which is equipped with a large number of holes with a diameter of 1 to 3 mm. ... is provided.

This air diffuser 2. Since the pore diameter is approximately 1 to 3 mm, no microbubbles are generated, but the energy consumption required for bubble generation can be significantly reduced compared to an air diffuser that produces microbubble noise.

3. is a porous layered material; 4. A frame body that completely prevents air bubbles from escaping to the side at the lower part of the outer periphery of 5.・The gas film forming member is completely attached to the frame body 5. - is a column 6 that stands upright in the gas dissolving tank 1. is fixed. Porous layered material 4
．． is a diffuser pipe 2. - Since the air bubbles that have risen further are temporarily retained and are filled throughout the pores through which fine air bubbles can pass, the air bubbles gradually accumulate below the porous layered material 4, forming a gas film A,... gas film A that is actually formed.

- The maximum thickness of the porous layered material 4. Pore size, porous layered material4.・Hydrophilicity of the material.

It varies depending on the surface tension of the liquid, etc., but when these elements are specified, when the gas film A,... reaches a predetermined thickness determined by the elements, the equilibrium is broken and the porous layered material 4 ．． Bubbles are generated all at once from the entire surface of ... and rise to the upper stage. Therefore, the maximum thickness of the gas film A, . If the thickness (length in the vertical direction) of . . . is set large, the gas film A, .・It will pass through the pores and form bubbles. Porous layered material4.・・・
If the gas film is formed to be excessively thick due to reasons such as small pore size, if an impact force is applied intermittently to the gas film forming member 3 as described later, the gas The entire membrane can be kept relatively thin. Even when the gas film reaches a predetermined thickness and the equilibrium is broken and bubbles are formed, some of the gas still remains in the porous layered layer 4.
will remain on the underside of the gas, always retaining at least some gas film. Therefore, the gas film and the liquid are always in contact over a fairly wide area, and the gas dissolution efficiency can be maintained at a high rate even though no energy consumption is required. Porous layered material4. ...for example, perforated plates, net-like materials,
It is a cloth-like material, etc., and its pore size is 0.2 to 2.
0 cabinet is desirable. Also, the frame body 5.・Thickness is 30~10
Zero throat is desirable.

Figure 3 shows an example of the relationship between the pore size and gas membrane thickness of a porous layered material in fresh water. It can be seen that a moderate gas film is formed in the case of 2.0 pus. As mentioned above, the thickness of the gas film varies depending on various factors, but in the example shown in FIG. 3, polyester tack (5), cotton gauze (B), and polyvinylidene chloride net (0) were used.

7 is an impact applying member for applying an impact to the gas film forming member 3, and the impact member 7 is a movement regulating member 8. ...
A protrusion 1 provided on a vertical rod 9 that is movable only in the vertical direction
The claws 12 of the rotating member 11 which is driven twice at zero rotate intermittently from below, lift it up, and when released, cause the vertical rod 9 to fall onto the tips of all the columns 6, forming a gas film via the columns 6. A shock 2 is applied to the member 3 with vertical movement to prevent an excessive increase in the thickness of the gas film.

As an example of sewage treatment, a 6-stage gas film forming member is installed in a standard activated sludge method treatment equipment for domestic wastewater with a BOD of 200 ppm, and the amount of air supplied is reduced to 1/1 of the standard activated sludge method.
When operated under No. 3, treated water with a BOD removal rate of 97% was obtained.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, air bubbles are generated from a simple air diffuser member having holes with a relatively large diameter, so that all the air bubbles can be generated with energy saving, and the air bubbles rise from the air diffuser member. The bubbles are held in the multi-stage porous layered material in sequence from the first stage, and a gas film is constantly formed. Both the upper and lower surfaces of the membrane are in constant contact with the liquid, making it possible to maintain high gas-liquid contact efficiency and dissolution efficiency with a smaller gas supply amount than in the conventional case where all microbubbles are generated. .

FIG. 2 is a side sectional view showing an example, FIG. 2 is a perspective view of the porous layered material, and FIG. 3 is a graph showing the relationship between the pore size and the thickness of the gas film of the porous layered material.

1: Gas dissolution tank 2: Diffuser 4: Porous layered material A: Gas membrane Figure 3

Claims (1)

[Claims] A multi-stage system in which gas is ejected as bubbles from a diffuser member having holes with a diameter of 1 to 3 mm provided at the bottom of a gas dissolving tank filled with a liquid to be dissolved, and having pores provided above the diffuser member. A gas dissolving method characterized in that air bubbles are held in the form of a film below each porous layered material and brought into contact with a liquid.