Energy recovery through a water-hydraulic motor in a small scale RO desalination system

Abstract

The use of energy recovery devices (ERDs) is now well known in seawater desalination. These devices are classified into two kinds of ERDs — one is the centrifugal turbine type and the other is the positive displacement type. However, because these ERDs are appropriate for large-scale reverse osmosis (RO) systems, a different type of ERD suitable for small-scale RO systems is required. For energy recovery in small desalination plants, hydraulic pump-hydraulic motor assembly is preferred due to the benefits including high efficiency, low pulsation, and no maintenance. For this reason, we are developing an integrated pump combined with energy recovery function. That is, the pump and motor pistons are contained in one cylinder barrel so that this integration can provide compact design. In this work, we present the experimental results of the small reverse osmosis system equipped with a water-hydraulic motor of axial piston type based on the swashplate principle for feasibility test about the mechanism of ERD-...