Rectangular Airlift Pumps

Proceedings of the 9th International Conference on Recirculating Aquaculture; Roanoke, VA; 08/24/2012, pp. 76-78.

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RECTANGULAR AIRLIFT PUMP DESIGN

William A. Wurts, Senior State Specialist for Aquaculture

Kentucky State University CEP

P.O. Box 469, UKREC, 1205 Hopkinsville Street, Princeton, KY 42445, USA

https://www.researchgate.net/profile/William_Wurts

Documented examples of rectangular airlift pumps appeared in the early 1970s (e.g. Salser and Mock, 1973).  These designs used single horizontal air injectors: either air stones/diffusers or a cylinder with perforations around the perimeter.  Recent rectangular airlifts have used injection grids fabricated with fine-pore diffusers or cylinders with multiple perforations.  Shortcomings of these grids are air-flow limitations and injector spacing constraints.  System air pressures must be increased to deliver high volumes of air flow.  Fine-pore diffuser fouling with bacteria, fungi and other micro-organisms also limits air flow.

In late 2006 and early 2007, Wurts designed and Herron built a prototype rectangular airlift pump. It was submitted to the USPTO as a provisional patent (Wurts and Herron, 2008) and again as a non-provisional patent application with new design elements/improvements added by Wurts (Wurts and Herron, 2009).  The designs employed either single- or dual-cylinder, horizontal air injector elements.  Air was injected through portals (circular apertures) in the cylinder walls.  Unlike earlier documented designs, the air-injector portals were placed in bilateral single or double rows, just above the mid-lines of the injector cylinder.  The lower-most air portals were tangential to the top of the injection cylinder’s mid-lines.  The bilateral configuration of air portals provided symmetrical airstream distribution, more precise injection depths and air-stream exposures to equal volumes of water – both sides of the air streams.

Rectangular airlifts can be substantially more compact and space efficient than single or multiple configurations of cylindrical airlifts.  A single, compact rectangular airlift (Wurts and Herron, 2008 and 2009) can handle the total air output of one or two regenerative/centrifugal blowers.  The rectangular airlift pump can generate high volume water-flow rates at relatively low static air pressures.  Air Pump software (Reinemann and Timmons, 1988) indicates a single rectangular airlift should pump water volumes of 9538-11960 Lpm/kw,  with an air flow of 2284 Lpm/kw and riser volume from 0.18-0.21 cubic meters (1890-2370 gpm/hp, air flow 60.5 cfm/hp and riser volume from 6.38-7.35 cubic feet).

Pond test of the Wurts-Herron rectangular airlift prototype in April 2007.

Side view of single and dual-cylinder air injector configurations.

Dual-injector air delivery system configurations.

References

Salser, B.R. and C.R. Mock.  1973.  Airlift circulator for algae culture tanks.  Proceedings of the annual workshop – World Mariculture Society, 4: 295–298.

Reinemann, D.J. and M.B. Timmons.  1988.  Airpump version 1.0.  Airlift Pumping and Aeration Design Program.  Cornell University Agricultural Engineering Department, Ithaca, NY.

Wurts, W. A., S. G. McNeill and D. G. Overhults.  1994.  Performance and design characteristics of airlift pumps for field applications.  World Aquaculture, 25(4):  51-54.

Wurts, W.A. and R.G. Herrron.  2008.  Airlift pump.  Provisional patent, USPTO 61/072,198.

Wurts, W.A. and R.G. Herrron.  2009.  Airlift pump.  Non-provisional patent application, USPTO 12/383,779 (publication suppressed).