This type of apparatus is composed of a fairly long bundle of tubes topped with a separator. The film of liquid is drawn through the tubes from the bottom to the top by the evaporation vapour that is produced. The tubes are heated from the shell side by steam, hot water or thermal fluids.
The original Kestner apparatus, as it was patented in 1899, had tubes of seven meters long and of various diameters, depending on the working conditions and the characteristics of the processed liquids. This apparatus can be adapted in many practical ways: lateral separator, one or more recirculation passes of liquids, various diameters and lengths of tubes.
A: Product
B: Vapor
C: Concentration
D: Heating steam
E: Condensate