摘要:
A method of preventing scale from being deposited in case of producing fresh water from sea water by heating the sea water in a vapour pressure type evaporator and multiple stage flush evaporator and by condensing water vapour evolved to obtain the fresh water comprising adding to the sea water small amount of seed crystal selected from the group consisting of calcium carbonate and magnesium hydroxide together with a surface active agent selected from the group consisting of a nonionic active agent and cation surface active agent.