Evaporators for Coarse Vacuum

This chapter describes some typical evaporator types. Working pressures between 80 and 800 mbar abs characterise the coarse vacuum. Water temperatures between 42 and 93 °C correspond to these pressures. Most of the watery solutions are evaporated in this range. The evaporator types which are used here are hardly different from those used in the pressure range. The chapter examines different substance-specific and economic criteria for the selection of an evaporator. Evaporators for the pharmaceutical and food industry have to be cleaned every day for bacteriological reasons. The cleaning time reduces the production time and should therefore be short. The natural circulation evaporator is the classic evaporator type. The climbing-film evaporator is the further development of the natural circulation evaporator. Plate evaporators can be chemically cleaned, but a mechanical cleaning with high-pressure ejector is very difficult.