The hydraulic turbocharger™: a new type of device for the reduction of feed pump energy consumption in reverse osmosis systems

Abstract

Pump Engineering, Inc. (PEI) has developed a new type of reject stream energy recovery device for brackish and seawater reverse osmosis systems called the Hydraulic Turbocharger™ (HTC). The device is a feedwater lubricated, free running, high speed turbine driven pump that provides a pressure boost to the RO feed stream resulting in a reduction in high pressure pump energy requirements. A pre-production prototype was tested at the Naval Civil Engineering Laboratory (NCEL), Port Hueneme, CA in conjunction with the development of a 1200 gph Reverse Osmosis Water Purification Unit (ROWPU). Testing consisted of approximately 2000 operating hours in a simulated RO system operating at a nominal 60 gpm of feed flow using Pacific Ocean seawater to determine unit reliability under actual seawater operating conditions. The device operated without any failure although a performance loss did occur that was attributed to galvanic corrosion between graphite and bronze sealing surfaces. Bronze/graphite interfaces were upgraded to either silicon nitride/graphite or silicon nitride/bronze surfaces and testing resumed to determine performance characteristics of the new seal and bearing configurations.