METHOD OF EVAPORATING AND CONCENTRATING FOAMABLE LIQUID

PROBLEM TO BE SOLVED: To suppress foaming surely at a low cost by a simple and easy operation. SOLUTION: In an evaporating and concentrating method, a foamable original liquid is circulated while it is supplied to a retained liquid retained in a liquid reserving part formed in the lower part of a main body part of an evaporating and concentrating apparatus and heated and evaporated to concentrate the original liquid, where in fresh water is used as the retained liquid in the liquid reserving part. This method has a process including the main steps of a fresh water supply step S1 , a vacuum forming step S2 , a retained liquid circulating step S3 , a steam supply step S4 , a steam condensing step S5 , an original liquid supply step S6 , a concentrating step S7 and the like. Because the original liquid is supplied to the fresh water little by little and evaporated, the original liquid in the liquid reserving part reaches the boiling point as a whole at the same time and is evaporated, so that a large quantity of foam is not developed. Only an operation to supply the fresh water is added to a normal concentration operation to simplify the apparatus and the method and to suppress the additional heating energy.