Brine entrainment in multistage flash desalination

Abstract

Brine entrainment in the multistage flash desalination depends on the stage temperature. In the once through and the brine circulation systems, brine entrainment is high in the low temperature stages. In the brine circulation system and during winter operation, decrease in the feed seawater temperature requires operation of the cooling seawater recycle pump. This is to control the intake seawater temperature. Adoption of this technique might not be the optimum choice. This is because of the short duration of the winter period. Also, preparation and maintenance of this large size pump might not be technically feasible and would come at very high cost. Failure to operate the cooling seawater pump results in large increase in the product salinity. Therefore, it is necessary to extract product water from the first stages to supply the makeup boiler water. In the once through system, there is no control on the feed seawater temperature. Therefore, the product salinity increases during winter operation. This would also call for product extraction from the high temperature stages. makeup water. Parametric analysis is presented for variations in the product salinity as a function of the feed seawater temperature.