Energy Recovery Devices (ERDs) are widely used in seawater reverse osmosis (SWRO) systems with turbochargers and rotary ceramic isobaric chambers or CICs dominating the market. The White Paper ERD Efficiency – What Systems Builders and Consultants Need to Know explores in detail ERD potential to reduce SWRO energy consumption in realistic field conditions with a focus on mega-scale systems. The results show that both types of ERDs are approximately equal in the potential to reduce net energy consumption.
This paper will focus on the motorized turbocharger ERD or HEMI (Hydraulic Energy Management Integration) for SWRO applications. The HEMI can often have the lowest SEC value any commercially available ERD. However, its most unique and advantageous features are the ability to provide complete control of feed flow and pressure and brine flow and pressure. In short, the HEMI provides RO membrane control as well as effective energy recovery in a compact and relatively low-cost package.
The HEMI reduces CAPEX by eliminating the multiple megawatt variable frequency drive (VFD) on the high-pressure pump (HPP) and reducing the size and cost of the HPP, motor and power supply system. These savings can pay for the cost of the entire HEMI installation in many cases. A low net CAPEX and superior energy savings means a significant reduction in the cost of permeate.
Reverse osmosis (RO) systems reject a portion of the high pressure (HP) feed as HP brine. Energy Recovery Devices (ERDs) recover brine hydraulic energy thereby reducing net energy consumption. This paper will focus on motorized turbocharged ERDs – the Hydraulic Energy Management Integration or HEMI.