Modular arrangement of falling film multiple effect evaporator

Claim 1

A falling film, forward flow, multi-effect evaporator comprising a plurality of relatively thin, prismatic, modular, compartmented shell sections disposed in a plurality of parallel rows along their longer dimensions, each modular shell section having thru openings on its opposite, large faces and having walls therein dividing said modular shell section into (1) an upper, liquid conveying compartment with a perforate floor to distribute liquid streams as a film on heat transfer surfaces, (2) a vertically partitioned central compartment one subchamber of which receives the liquid streams and the other subchamber of which receives released vapor from the streams thru the partition perforations, and (3) a lower compartment also subdivided into separate chambers to receive concentrated liquid and condensed vapor respectively thru perforate floors of said subchambers, a plurality of separator sheets of heat transfer material interposed between said rows of said modular shell sections, said walls of said sections and said sheets providing the principle heat transfer surfaces, said sheets being disposed to effectively provide said heat transfer surfaces between said rows, necessary to transmit heat from a set of sections in which vapor is being condensed, to the immediately downstream set of sections in which liquid film is being evaporated, said sections being arranged in sets which comprise a plurality of parallel disposed, modular sections, said sets extending in a direction perpendicular to the rows, at least one set interdigitating with two adjacent sets to provide sufficient temperature and pressure differentials between adjacent sets of sections to provide a vapor lift to raise liquid from said lower liquid compartments of one set of sections to said upper liquid conveying compartments of that adjacent set of sections which is immediately downstream of said one set, with respect to liquid and vapor flow.