Co-precipitation in multiple-effect distillers at nonconventional temperatures

A model has been developed to predict alkaline scale formation in seawater multiple-effect distillers (MED) at high top brine temperature (TBT). The effects of changes in solution composition due to CO2 release on the formation of crystalline scales in seawater evaporators are studied. Supersaturations of scaling salts are calculated by applying mass and charge conservation equations while considering chemical reactions involved in the process. Pitzer model was used for the activity coefficient calculations. Simulations allowed predicting co-precipitation of alkaline scale: magnesium hydroxide and calcium carbonate. These salts are responsible for scale build-up. Simulation results matched well with the reported experimental data for high TBT in MED.