Pilot testing of a novel Multi Effect Distillation (MED) technology for seawater desalination

Abstract

This work presents an improved evaporator design of the Multi Effect Distillation (MED) to minimize the thermal losses and footprint of the evaporator. An advanced modular MED pilot plant has been installed with a nominal capacity of 25 m3/day to validate the concept under a seawater salinity of 57,500 ppm (Dukhan Coast, West of Qatar), at the top brine temperature of 65 °C. Both the pilot testing and the simulation results confirm the features of the novel design of the MED. By implementing this invention's design, the heat transfer area has been decreased and accordingly, the capital cost of the evaporator is reduced by 20%. The tube arrangement with new vapor route allows the removal of the traditional demister, which accordingly reduces the footprint of the desalination plant by 65%. The sieve tray for spraying the seawater over the rectangular and inline tube bundle creates a uniform wettability. The improved design also discloses the utilization of an online vent water-ejector, for vent out of the non-condensable gases (NCGs). The novel evaporator design based low temperature MED technology, shows a potential solution for the industrial applications of high salinity byproduct and solar desalination.