Comparison of two types of energy recovery devices: Pressure exchanger and turbine in an island desalination project case

Energy recovery device (ERD) is a crucial part in the seawater desalination system. The past decade has seen a growth in attempts to carry out the structure and working principle of different types of ERDs, yet fewer quantitative comparisons have been made on two mainstream ERDs: pressure exchanger (PX) and turbine ERD. In this study, the effective energy conversion efficiency (EECE), energy consumption, and noise of two types of ERDs applied in an island in China are obtained by collecting and collating their long-term operation data. The results showed that the EECE of PX ERD was 93.9%, 15.5% higher than that of turbine ERD. The energy consumption of PX ERD is 3.03 kWh/m3, slightly lower than that of turbine ERD, about 0.34 kWh/m3. The gap between EECE and energy consumption is caused by the different structures and working principles of two types of ERDs. Moreover, the operating noise of turbine ERD is better than that of PX due to its high rotation speed. This study also makes an economic analysis on the investment and operation cost of the whole system, and gives the engineering application suggestions and selection guidance of ERDs.