What is the function of an Airlift pump?
The air lift pump is a low suction pump that moderately discharges solids accompanying liquid. The pump injects compressed air into the bottom of a pressure tube that is submerged in liquid.
How do they work?
Airlift pumps (also known as mammoth pumps) take advantage of increased oxygen uptake in the water under pressure. At the same time, the rising air lifts and circulates the water. This makes the mammoth pump suitable for aeration and circulation of large amounts of water. Air lift pumps are often used in situations where maintenance needs to be minimized. The pump itself has no rotating parts, just a riser tube that combines liquid and air. The entire pump system is not 100% maintenance free as it requires equipment to inject air into the pump.
Air is directed to the bottom of the riser, where it combines with the liquid. This changes the density of the liquid and the combined medium rises through the tube.
The efficiency of the airlift pump depends on two factors:
1: Underwater length (hs) relative to ground height (hg)
The speed of air passing through the fluid and the speed of the medium passing through the pump. The greater the difference between the fluid and air velocities, the lower the overall efficiency of the pump. Under optimum conditions, the airlift pump can achieve an efficiency of about 35-40% with Hs/Hg= 2/2.5 and airspeed 10 m/s.
In air lift pumps, compressed air is mixed with water. Water is much denser than air. Buoyancy causes air, which is less dense than liquid, to rise rapidly. Due to the hydraulic pressure, the liquid is caught in the updraft and moves in the same direction as the air.
Air is supplied to the bottom of the riser pump, which combines with water to form bubbles. When water mixes with air, the density of the water is reduced. A mixture of air and water, also known as bubbles, is much less dense than water. Therefore, the main principle of the air lift pump is the air-water mixture and the water density difference. In these pumps, the air injector system takes the form of an air jacket, with multiple radial holes in the tube, and air is supplied from the surrounding manifold.
Air lifts pump parts
1) Air compressor
Air compressors are used to compress air and supply pressurized air to airlines. Compressed air is typically produced by an engine-driven air compressor, but windmill-driven air compressors are also used.
Compressed air is sent to the pressure line through this airline. The upper end of this tube is connected to the air compressor and the air nozzle is attached to the lower end.
3) Pumping pipe
This pipe is used to pump water from a well. A mixture of water and air rises through this pipe. Both ends of the conveyor pipe are open. The bottom edge of this tube is submerged in water from which it is lifted.
Airlift pumps are used at
1) Airlift pumps are often used in highly polluted wells where it is difficult to use conventional pumps because sand rapidly wears mechanical parts.
2) These pumps are also used to collect fauna samples from sediments.
3) If a small head is needed, it may be used in sewage treatment facilities.
4) It is also used for deep sea mining.
5) It is also used for collecting archaeological relics.
6) Sometimes used to pump water for filtration in an aquarium.
Airlift pumps are a very essential commodity for advanced water treatment plants as they can work easily at places where small head is required and use oxygen bubble energy for pumping, hence sewage treatment plants should incorporate airlift pumps in the treatment scheme.