Energy recovery pump in reverse osmosis desalination plants

Abstract

This paper presents an operational analysis of the prototype of an innovative fully autonomous wind powered desalination system. The system consists of a wind farm, made up of two wind turbines and a flywheel, which operates in isolation from the conventional power grids and which supplies the energy needs of a group of eight reverse osmosis (RO) modules throughout the complete desalination process (from the pumping of sea water to the storage of the product water), as well as the energy requirements of the control subsystems. The analysis of the electrical and hydraulic results obtained from this prototype, installed on the island of Gran Canaria in the Canarian Archipelago, shows the technical feasibility of the system design and the automatic operational strategy programmed for it. Amongst other tasks, the automatic operational strategy controls the number of RO plants that have to be connected or disconnected at any given moment in order to match the variable wind energy supply. The results obtained thus far have not revealed any significant variation in the level of quality or average volume of the product water, nor any physical deterioration to the main components of the system as a result of the start-ups and shut-downs required as a result of the variations in the wind energy supply or oscillations of the electrical parameters of voltage and frequency. In conclusion, the system under analysis can be applied to sea water desalination, both on a small and large scale, in coastal regions with a scarcity of water for domestic and/or agricultural use but with wind energy resources.