A low energy thermally driven seawater desalination by direct spray method: An Experimental Study

Thermal desalination processes, such as the multi-stage flashing (MSF) and the multi-effect distillation (MED), played a dominant role in seawater desalination within GCC countries, due to its high efficiency, low maintenance and ability to operate in higher silt and salt concentrations However, these desalination plants are prone to having high capital cost at >US$2000 per m3, almost two-fold higher than the membrane-based plants. The authors proposed a tubeless direct-spray of seawater into an empty chamber of saturated states where the excess enthalpy, between the differential pressures and temperatures of feed to those in the flashed chamber, is allowed to flash into vapour under low vacuum. Being devoid of tube-based heat transfer resistances, the initial CAPEX will be much lower, typically <US$800 per m3. Moreover, it can handle feed of high salt concentration without the fear of scaling within the flashed vessel. To boost the flashing phenomenon, an injection of micro-vapour bubbles (MVB) was incorporated into the seawater feed prior to its injection via the nozzles. The MVB embedded feed has the potential to increase the flashed rates by two-fold due to the higher surface area of vapour bubbles at the point of flashing.