The integration of water vane pump and hydraulic vane motor for a small desalination system

An integration of water vane pump and hydraulic vane motor was introduced in small reverse osmosis (RO) system, in which the hydraulic vane motor was used as energy recovery device. The hydraulic performance and energy consumption of one combination of pump and hydraulic motor were investigated under different operation conditions. This type of integration pump reduces energy cost and simplifies the system setup, thus it could be an alternative choice for small RO desalination system. Our results demonstrated that the improvement of volumetric efficiencies of the pump and the hydraulic motor was the main factor to increase the prototype pump performance. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved.

This paper shows that the combination of a water hydraulic vane pump and a vane hydraulic motor is a feasible approach for small driven membrane system. The prototype pump was investigated under pressure conditions of membrane module. The energy reduction percentage was about 20% at the maximum operation pressure. From the experiment results, volumetric efficiencies of the pump and motor elements mainly affect hydraulic performance and energy consumption of the prototype pump. Compared with other ERDs, the prototype pump is easier to operate and maintain. The cartridge design of the prototype pump is simply to replace the pump or hydraulic motor element to change displacement, which adapt the recovery ratio of membrane module. Like Danfoss APP–APM system, two elements in the prototype pump are fixed displacement and connected by a shaft with the same rotation speed, so the membrane system has constant recovery ratio and less flexibility. When the performance of the membrane module and the pump/motor element are accurately designed, the membrane separation system can reach optimized operation conditions. Nomenclature QS feed flow rate, m3/h Q B1 flow rate of high pressure concentrate, m3/h Q B2 flow rate of low pressure concentrate (drain), m3/h Qp permeate flow, m3/h Q S0 the outlet flow rate of pump element without load pressure, m3/h Q B10 the inlet flow rate of hydraulic motor element without load pressure, m3/h. ηVP volumetric efficiency of vane pump element,% ηVM volumetric efficiency of hydraulic vane motor element, % η system recovery, % pSL inlet pressure of vane pump, bar pSH outlet pressure of vane pump, bar pBH inlet pressure of hydraulic vane motor element, bar pBL outlet pressure of hydraulic vane motor element, bar P power consumption, kW PP power consumption of pump element, kW PI power consumption of the integration of two elements, kW PP −PI E energy reduction percentage, E = ,% PP WI specific power consumption of the integration of two elements, kWh/m3