On the National Oilwell Varco (NOV) booth at the International Desalination Association’s World Congress in Perth in the first week of September 2011 was a working model of a brand new positive-displacement pump for desalination.
The creation appropriately of two Western Australians, Daryl Wheeler and Courtney Wheatley, the Constant Swept Volume (CSV) pump is very different in that the pump body revolves around a static central shaft. Constant swept volume describes the flow through the pump which is smooth, uninterrupted and never reverses direction.
The main components of the pump are the gates, stator, housing, cam and lifters, and seal plate. The pump is a system of matched gates that rise and fall in a timed sequence to form a constant volume of fluid.
The rotation of the outer housing around the shaft allows for a tenfold increase in the power density of the pump, says NOV. The cam system is timed to allow for pressure balancing across gates before lifting or lowering them to minimize wear on gates.
The pump offers a small footprint and runs quietly. It is manufactured in duplex stainless steel with a leakproof sealing mechanism.
NOV’s technical sales chief, Bill Weatherholt, told D&WR that the pump is currently undergoing trials in a 250,000 GPD (950 m³/d) train in the Caribbean, which will conclude in the fall of 2011. Pumps are also under trial in two other sites.