Multi-effect evaporator

A thermal desalination system adapted to produce distilled water from feed water, comprising a forward feed evaporator comprising a main water feed line, a main vapor feed line, a distilled water main line and a plurality of effect groups, wherein each effect group comprises:

• a) a common concentrate drainage line,
• b) a parallel water inlet, and
• c) a plurality of effects, each of said effects comprising:
• i) at least one vapor inlet;
• ii) at least one water inflow line fed by said parallel water inlet;
• iii) at least one concentrate outflow line draining into said common concentrate drainage line;
• iv) at least one first vapor and distilled water outlet in fluid communication with said distilled water main line;
• and
• v) heat transfer apparatus for receiving thereon feed water from said at least one water inflow line, and therein inlet vapor from said at least one vapor inlet and to condense a part of said inlet vapor to produce distilled water to drain out of said at least one first vapor and distilled water outlet into said distilled water main line, leaving the remainder of the inlet vapor as a first outlet vapor, and to produce from said feed water a second outlet vapor, leaving the remainder of said feed water as a concentrate to drain out of said at least one concentrate outflow line;
• wherein said main water feed line provides feed water to the parallel water inlet of a most upstream effect group of said plurality of effect groups;
• wherein the common concentrate drainage line of any upstream effect group feeds the parallel water inlet of its adjacent downstream effect group such that said effect groups are serially connected through their respective common concentrate drainage lines;
• wherein the concentrate temperature decreases from said most upstream effect group to a most downstream effect group of said plurality of groups, while the concentrate becomes increasingly concentrated from said most upstream effect group to said most downstream effect group where the combination of said decreasing temperature and said increasing concentration minimizes corrosion and scaling in the effects.