Patent ID: 7799178

Claim:
A distillation method for producing distillate from a feed water stream containing at least one dissolved material in a plurality of effects, each of the effects comprising a vessel, a heat exchanger and devices for transporting fluids, each of the effects receiving a feed water, a heated feed water or a combination thereof, the method comprising: a) passing a portion of the feed water at a first temperature to at least one effect and through a heat exchanger wherein the at least one effect to produce a distillate vapor and brine from the at least one effect; b) separating the distillate vapor from the brine; c) heating at least a portion of the heat exchangers by passing a stream comprising at least one of steam and distillate vapor from a downstream effect to the heat exchanger in the first effect at a second temperature; and, d) further heating a second quantity of the feed water by heat exchange with at least one external heat source to a third temperature greater than the first temperature to produce a heated feed water and passing a portion of the heated feed water to at least two effects.