Airlift pump

An airlift pump, powered by compressed air, raises uid by en-training gas to reduce its density. 1. Air supply. 2. Liquid supply.3. Air inlet port. 4. Air supply line. 5. Air port. 6. Air outlet.7. Fluid intake. 8. Riser tube. 9. Air liquid mixture. 10. Pumpoutlet. L:Liquid, usually wastewater. LL:Liquid level. V:VesselG:Gravel or solids.

AnAirlift pump is a pump that has low suction andmod-erate discharge of liquid and entrained solids. The pumpinjects compressed air at the bottom of the discharge pipewhich is immersed in the liquid. The compressed airmixes with the liquid causing the air-water mixture to beless dense than the rest of the liquid around it and there-fore is displaced upwards through the discharge pipe bythe surrounding liquid of higher density. Solids may beentrained in the ow and if small enough to t throughthe pipe, will be discharged with the rest of the ow at ashallower depth or above the surface. Airlift pumps arewidely used in Aquaculture to pump, circulate and aeratewater in closed, recirculating systems and ponds.[1] Otherapplications include dredging, underwater archaeology,salvage operations and collection of scientic specimens.

1 PrincipleThe only energy required is provided by compressed air.This air is usually compressed by a compressor or ablower. The air is injected in the lower part of a pipe

that transports a liquid. By buoyancy the air, which hasa lower density than the liquid, rises quickly. By uidpressure, the liquid is taken in the ascendant air ow andmoves in the same direction as the air. The calculationof the volume ow of the liquid is possible thanks to thephysics of two-phase ow.

2 UtilizationAirlift pumps are often used in deep dirty wells wheresand would quickly abrade mechanical parts. (The com-pressor is on the surface and no mechanical parts areneeded in the well). However airlift wells must be muchdeeper than the water table to allow for submergence. Airis generally pumped at least as deep under the water as thewater is to be lifted. (If the water table is 50 ft below, theair should be pumped 100 feet deep).It is also sometimes used in part of the process on awastewater treatment plant if a small head is required(typically around 1 foot head).Airlifts are used to collect fauna samples fromsediment.[2] Airlifts can oversample zooplanktonand meiofauna but undersample animals that exhibit anescape response.[2]

3 InventorThe rst airlift pump is considered to be invented by theGerman engineer Carl Emanuel Lscher , who lived inthe second part of the eighteenth century. He discoveredthe airlift pump in 1797.

4 Advantages and disadvantagesThe following paragraph exposes the advantages and dis-advantages of the airlift pump compared to other pump-ing techniques.

4.1 Advantages

The pump is very reliable. The very simple principleis a clear advantage. Only air with a higher pressurethan the liquid is required.

1

2 6 NOTES AND REFERENCES

The liquid is not in contact with any mechani-cal elements. Therefore, neither the pump can beabraded (which is important for sandwater wells),nor the contents in the pipe (which is important forarcheological research in the sea).

Act as a water aerator and can in some congurationslift stagnant bottom water to the surface (of watertanks).

Since there are no restrictive pump parts, solids upto 70% of the pipe diameter can be reliably pumped.

4.2 Disadvantages

cost: while in some specic case the operational costcan be interesting, most of the time, the quantity ofair to compress is high compared to the liquid owrequired.[3] [4] .

Conventional airlift pumps have a ow rate that isvery limited. The pump is either on or o. It is verydicult to get a wide range of proportional ow con-trol by varying the volume of compressed air. Thisis a dramatic disadvantage in some parts of a smallwastewater treatment plant, such as the aerator.[5]

The suction is limited.

This pumping system is suitable only if the head isrelatively low. If you want to obtain a high head, youhave to choose a conventional pumping system.

Because of the principle, a lot of air remains in theliquid. In certain case, this can be problematic, as,for example, in a waste water treatment plant, beforean anaerobic basin.

4.3 Design improvements

A recent (2007) variant called the geyser pump canpump with greater suction and less air. It also pumps pro-portionally to the air ow, permitting use in processes thatrequire varying controlled ows. It arranges to store upthe air, and release it in large bubbles that seal to the liftpipe, raising slugs of uid.[6]

5 See also

Airlift (dredging device)

Pipe network analysis

Pulser Pump

A geyser pump, an improved airlift pump, powered by com-pressed air, raises uid by forcing rising bubbles to displace uid.50. Air supply. 52. Air inlet port. 58. Liquid supply. 60,62. airsupply lines. 64. upper end of air tank 86. 66,82. Air ports. 70.Upper air inlet of u-shaped elbow 74. 76 Air outlet. 84. Fluidintake. 65. Riser tube. 88. Displaced liquid. 90. Pump out-let. L:Liquid, usually wastewater. LL:Liquid level. VVV:VesselG:Gravel or solids

6 Notes and references[1] http://www.airlift.eu/

[2] Cahoon, LB; Lindquist, DG; Clavijo, IE; Tronzo, CR(1992). Sampling small invertebrates at the sediment-water interface. In: Cahoon, LB. (ed.) Proceedings ofthe American Academy of Underwater Sciences TwelfthAnnual Scientic Diving Symposium Diving for Science1992. Held September 2427, 1992 at the University ofNorth Carolina at Wilmington, Wilmington, NC. AmericanAcademy of Underwater Sciences. Retrieved 2013-04-05.

[3] air quantity calculation PDF (1.86 MB)

[4] airlift basic calculation - dead link, 15 April 2013Template:Xls

[5] New Pump TechnologyMay Improve Small Flows, WVUNCSFC Clearinghouse Accessed 2011-3-21

[6] Patent Application number: 11/654,448, January 17,2007, Inventor: Masao Kondo

Airlift calculation by Sanitaire (pdf document) theselinks are no longer valid

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