Natural Circulation Evaporators

Natural circulation evaporators utilize vertical tubes which operate by the thermo siphon principle. 

Process
The density difference between the boiling liquor and the circulating liquor produces the driving force for liquid circulation.  In operation, feed enters the lower liquor chamber. As it travels up the tubes and reaches boiling point, vapour forms and carries liquor to the separator. 

Most installations require liquor recirculation. When feed quantities are sufficient, however, single pass operation is utilized.

Applications
Typical applications include anhydrous caustic, beet sugar, foamy liquors, low or moderately viscous liquors and precipitating liquids.