System enables PD pumps for larger desalination plants

A new Integrated Pump and Energy Recovery (IPER) system for larger desalination facilities was introduced on 2 July 2012 at the Singapore International Water Week by GE.

GE claims it will reduce energy demands associated with pumping water by at least 10%.

Bahamas Water & Sewerage Corporation has installed a pilot IPER system at a desalination facility in Tarpum Bay to demonstrate the efficiency and reliability of the technology.

Lower-capacity desalination plants have often used positive-displacement (PD) pumps because of their high efficiency and availability. These small but efficient pumps are based on the use of a fixed geometry and either rotating axial pistons or crank-driven pistons to pressurize water in the chambers.

As the size and pumping capacity of these chambers increase, these smaller PD pumps face mechanical challenges. As a result, previous larger PD pumps have either featured a larger crankshaft or high crankshaft speeds to overcome these, but the larger size and operating speeds have led to significant vibration and maintenance issues.

IPER solves these problems, says GE, by eliminating the crankshaft and replacing it with a hydraulic drive system for both functions. The drive powers three double-acting pistons in the water displacement unit and does this at very slow cycle speeds compared with traditional PD pumps.

These innovations allow larger seawater reverse-osmosis systems using less efficient centrifugal pumps to incorporate IPER PD pumps in the future. Since PD pumps are typically used on systems with a capacity of less than 1,000 m³/d, this offers opportunities for any plant of 1,000 m³/d or larger to achieve substantial energy savings.

“IPER is designed to offer customers reliable uptime for their packaged desalination water treatment plants while reducing their energy costs in a significant and quantifiable way,” said Heiner Markhoff, president and CEO – water and process technologies for GE Power & Water. “IPER represents a major economic and technical break-through that is poised to help desalination operators play an even greater role in addressing the world’s mounting water scarcity problems.”