Distillation or evaporation processes are proven commercially feasible methods for conversion of sea water to fresh or potable water. In recent years multistage flash evaporators have largely replaced other types of distillation equipment particularly for large land based sea water conversion plants. Factors which contributed to the improved performance and economy of the flash evaporator include the following:
Development of sea water treatment chemicals containing complex polyphosphates such as Hagevap which inhibit scale formation from heat exchanger surfaces at temperatures up to 200 F.
Development of the multistage brine recycle flash evaporator which reduces treating chemical consumption and costs by reducing sea water makeup requirements and the amount of water requiring treatment.
Development of the long condenser tube bundle flash evaporator design wherein several evaporator stages can be installed for one set of tubes, thereby decreasing the quantity of relatively expensive tube sheets and water boxes for a given number of stages.
Development of the acid sea water treatment process which permits scale free evaporator operation at temperatures up to and above 250 F without excessive corrosion of evaporator copper alloy condensing tubes or steel flash chambers.
Improved design technology and fabrication methods which permit construction of large single unit multistage flash evaporators having capacities up to and above ten million gallons per day.
