14.7.6. Thin-layer or wiped-film evaporators
This type of unit, known also as a thin-film evaporator is shown in Figure 14.24. It consists
of a vertical tube, the lower portion of which is surrounded by a jacket which contains the
heating medium. The upper part of the tube is not jacketed and this acts as a separator. A
rotor, driven by an external motor, has blades which extend nearly to the bottom of the
tube, mounted so that there is a clearance of only about 1.3 mm between their tips and
the inner surface of the tube. The liquor to be concentrated is picked up as it enters by the