Evaporation method and its device null of the aqueous solution which includes the water soluble solute where the saturation solubility for the water is proportionate to temperature

摘要

PURPOSE:To reduce crystallization of a solute as scale on the surface of each horizontal heating tube of a heater when evaporating a water solution containing a water soluble solute having saturated solubility in water inversely proportional to temperature to the state of crystallization of the solute by a horizontal tube falling film evaporator. CONSTITUTION:A water solution after heated and evaporated on the outside surface of horizontal heating tubes 11c in an evaporator 10 at reduced pressure (under barometric pressure) is introduced into a flash evaporator 16 maintained at reduced pressure lower than that in the evaporator 10 where it is flashed. Then, after the water soluble solute is crystallized and the crystals are separated and removed, the water solution is sprayed over the outside surface of the horizontal heating tubes 11c in the evaporator 10.