Performance of hydraulic turbocharger integrated with hydraulic energy management in SWRO desalination plants

Hydraulic turbocharger is a common energy recovery device used in reverse osmosis water desalination plants to recover the stored energy in brine. Also, it can be used to control the pressure variation due to the change of plant operating conditions. The aim of the current work is to apply the computational fluid dynamics (CFD) to investigate the balance between the hydraulic turbocharger turbine and pump sections. The effect of changing the rotor speed and the effect of auxiliary line size and valve opening on the performance of the hydraulic turbocharger are also investigated. In addition, the effect of these changes on the plant specific energy consumption (SEC) is discussed. The results of the current work present the variation of the hydraulic turbocharger performance with the rotor speed. It also shows that increasing the turbine auxiliary line diameter reduces the turbine inlet pressure. The CFD results show that opening the auxiliary line reduces the turbine inlet pressure which reduces the rotor speed and the pump boosting pressure. © 2015 Elsevier B.V. All rights reserved.

The hydraulic turbocharger is an important element in water desalination plants. The current work investigates the hydraulic turbocharger as a device to control the changes in the plant operation point resulting from changes of temperature, salinity, fouling, etc. The present work introduces the performance results of the hydraulic turbocharger pump and turbine sections using CFD analysis. The energy and speed balance between the pump and the turbine are presented. The CFD results are used to explain the energy and speed balance in pump and turbine sections. The impact of controlling the hydraulic turbocharger on the plant efficiency is presented. The results also shows that increasing the auxiliary line diameter reduces the turbine inlet pressure hence reduces the membrane inlet pressure. Afterwards selected auxiliary line size was selected to assure a change of turbine inlet pressure of 15%. A ball valve is mounted on the auxiliary line and the effect of valve opening on the performance shows that increasing the valve opening reduces the turbine inlet pressure, turbine available power and the rotor speed. Acknowledgments The authors would like to acknowledge the Science & Technology Development Fund in Egypt (STDF), Project No. 3965, for funding the current research. The authors would like to acknowledge the expert guidance of Prof. Said H. Farghaly and Prof. Alaa M. A. EL-Butch.