Technology Overview

Breakthrough engineering is the core of ERI's Pressure Exchanger™ (PX™) energy recovery technology. It is no surprise that the PX is the most efficient energy recovery device (ERD) on the market. ERI has invested years in research and development as well as millions of dollars to build the most efficient ERD available today—up to 98% efficient, producing energy savings of over 60%.

Re-thinking SWRO
Though it has quickly become the benchmark ERD technology, ERI’s PX device was a new paradigm when first introduced to reverse osmosis (RO) systems. There are, consequently, fundamental differences between the way legacy Pelton and turbocharger devices are designed and optimized and the modern approaches used with PX device-based desalination systems. Some of the new concepts and rules being driven by ERI are:

  • Net transfer efficiencies up to 98%
  • PX device-equipped SWRO systems use less energy at lower recoveries (between 35% and 45%)
  • The high-pressure pump flow equals the systems permeate flow recovery rate
  • The high-pressure pump and permeate flows are independent of the reject flow
  • PX device efficiency is essentially independent of system flow rate and pressure changes

These fundamental concepts reverse many of the traditional rules that have constrained the RO desalination designer for many years. PX technology opens up new avenues for RO design and optimization using larger train sizes. It also allows the designer or operator to select a recovery rate which is optimum for a given salinity, temperature and membrane fouling performance. The papers below describe these ideas in detail:

SWRO Plant Optimization
A major economical benefit of PX device technology is that the PX requires a much smaller high-pressure pump than that used by conventional technology. Even more crucial, PX technology disassociates the high-pressure pump from the ERD. These two factors combine to give desalination plant designers much more flexibility in optimizing train sizes and selecting the best high-pressure pump for their project.