Patent ID: 8591705

Claim:
A multi-effect evaporator adapted for distillation of water, comprising a plurality of effects serially connected and arranged into groups including a most upstream group and subsequent downstream groups; each group having a most upstream effect and a most downstream effect and having a common parallel water feed inlet for supplying all effects in said group with feed water; the evaporator further including a main feed water line in fluid communication with the common parallel water feed inlet of the most upstream group; an array of heaters disposed along said main feed water line for heating said feed water before its entry into the common parallel water feed inlet of the most upstream group; each effect comprising heat transfer means for receiving thereon feed water from said parallel water feed inlet, and therein an inlet vapor and to produce from the feed water a first outlet vapor, leaving the remainder of the feed water as a concentrate, and to condense a part of the inlet vapor to produce distilled water, leaving the remainder of the inlet vapor as a second outlet vapor; each effect further comprising means for forwarding the first outlet vapor into an adjacent downstream effect, where it will constitute said inlet vapor, and means for forwarding said second outlet vapor into one of said heaters for heating thereby the feed water in said main water feed line; each group further comprising a pump for extracting the concentrate from the effects of said group and pump it into the common parallel water feed of an adjacent downstream group; and means for collecting the distilled water, wherein a vapor temperature decreases from the most upstream effect to the most downstream effect, and wherein the feeding of the heated feed water to the most upstream group and the pumping of the concentrate, being the remainder of the feed water, to the adjacent downstream group, are selected to yield introduction of the most dilute feed water to the hottest effect, to minimize corrosion and scaling in the effects, wherein the heat transfer means in each effect comprises a plurality of tubes with inter-tube spaces therebetween, the tubes being horizontal or tilted at an angle, receiving said inlet vapor, and contacting the feed water to cause heat transfer there resulting in the vaporization of a part of the feed water in the inter-tube spaces, to produce said first outlet vapor, leaving the remainder of the feed water as a concentrate, and resulting in the condensation of a part of the inlet vapor in the tubes, to produce said distilled water, leaving the remainder of the inlet vapor as said second outlet vapor, wherein the tubes in the hotter, more upstream effects contact a less concentrated feed water in respect to the tubes in colder, more downstream effects, the multi effect evaporator further comprising a plurality of dispersers, each arranged to introduce the inlet feed water to a corresponding effect as a vertical falling film.