Selection of aeration and diffusion device

11.
1.
1.
2 Selection of aeration and diffusion device

Choosing a suitable diffusion device and the corresponding coefficient are related to the processing effect of the process and operation
.

(1) The oxygen transfer efficiency and power efficiency make the aeration system work at high oxygen transfer efficiency and power efficiency, which is the purpose of selecting the aeration system
.

(2) Considering maintenance and management operations to fully improve the efficiency of the diffuser, it is necessary to consider the requirements and possible situations that may occur during the maintenance process
.

(3) Consider the organic combination of existing structures and systems.
Consider the difficulty of installing aeration and diffusion devices and whether the structures meet the requirements of new devices.
Not only must they adapt to the requirements of new processes, but also easy to replace with new devices.
Whether the equipment can meet the requirements should also be calculated
.

(4) Considering the high efficiency and low consumption of aeration equipment related accessories, aeration equipment is a system combination, and the high efficiency and low consumption of only a certain part cannot ultimately achieve the high efficiency and low consumption operation of the system
.

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1.
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3 Material of aeration diffuser

There are many materials for air diffusers, which can generally be divided into corundum ceramic materials, rubber materials, polyethylene materials and porous materials (ceramsite, coarse porcelain, etc.
)
.

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1.
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4 New aeration and diffusion device

In recent years, new technologies and new equipment have continuously appeared, and many achievements have also been made in aeration devices
.

Figure 11-10 shows the Jinshan I-type aeration nozzle
.

Figure 11-10 Jinshan Type I aeration nozzle

Figure 11-11SX-1 type aeration nozzle

Figure 11-11 shows the SX-1 aeration nozzle, which is installed on the horizontal pipe 200～300mm away from the bottom of the tank, and its material is ABC engineering plastic injection molding
.

Figure 11-12 shows the diffuse aerator
.
It is installed under the horizontal pipe at the bottom of the pool, the lower edge of the aerator is 150-200mm away from the bottom of the pool, and the diffuse aerator is made of polyvinyl chloride plastic by hot pressing
.
It is mainly composed of a sawtooth aeration head, a sawtooth diffuser, a deflector and an air inlet pipe
.
The aerator is in the shape of an inverted umbrella
.
Oxygenation is mainly accomplished by the violent mixing action of liquid, the two cutting action of bubbles and the diffusion action of the diffuser cover
.
After the gas enters the aerator through the pipe, it is cut for the first time by the sawtooth cloth air head through the central air inlet pipe, and then uniformly diffused by the diffuser cover and the deflector, and the surrounding liquid is driven to rise after the second cutting, making the gas and liquid violent Mixing accelerates the renewal of the water film at the gas-liquid interface
.
After the gas undergoes secondary cutting and gas-liquid mixing, the bubble diameter becomes smaller, which increases the gas-liquid contact area and facilitates the transfer of oxygen
.
The diameter of the diffuser hood is 40～60cm, the air supply of the diffuser is 8～14L/s, the oxygen utilization rate is 8.
5%, and the service area is 2～3m ² / piece
.
The characteristics of the diffuse air diffuser are high power efficiency, large air distribution range, high oxygen utilization rate, no clogging, low cost, and easy installation
.

Figure 11-12 Diffusion type air purifier structure
1-tooth-shaped air head; 2-secondary cutting teeth; 3-diffusive cover;
4-flow deflector; 5-secondary cutting teeth; 6-center tube

Figure 11-13 shows a static aerator (also called a fixed spiral diffuser), which was developed by an American company in 1972, and then Japanese scientists and technicians developed a single spiral into a double spiral form
.
The static aerator is composed of a circular shell and spiral blades fixed inside the shell.
The rotation angle of each spiral blade is 180°, and the rotation directions of two adjacent blades are opposite
.
The air enters the device through the air distribution pipe from the air distribution hole at the bottom and flows upward.
Due to the difference in the density of the mixed liquid inside and outside the casing, the lifting effect is generated, so that the mixed liquid continuously circulates inside and outside the casing
.
When the air is rising, it is repeatedly cut by the spiral blades to form small bubbles
.
Diameter of the stationary aerator 0.
3 ~ 0.
45m, the length of 0.
3 ~ 1.
5m, with polypropylene or polyethylene, made of a material
.
The air flow rate of the diffuser is related to the size of the diffuser.
For a small diffuser, the flow rate is 5-10L/s, and the flow rate of a large diffuser is 25L/s
.
When using a static aerator, the water depth of the aeration tank should not be less than 4.
0m
.

Figure 11-13 Structure of static aerator

Related links: Common aeration and diffusion devices (2)