Figure 3 shows a schematic diagram for the forward-feed Multiple-Effect Evaporation (MEE-FF) seawater desalination process. The system includes the evaporators, equal to n, a series of feed water preheaters, equal to n-2, a train of flashing boxes, equal to n-1, a down condenser, and a venting system. In the forward-feed configuration, the direction of heat flow as well as the flow direction of the brine and vapor is from left to right, i.e., from effect 1 to effect n. The pressure in the effects decreases in the flow direction. Each effect contains heat exchange tubes, vapor space, brine spray nozzles, mist eliminator, and brine collecting box. The horizontal falling film evaporator is the most widely used in the MEE desalination processes. The advantages of the horizontal falling film system are: