Purification of caustic soda soln. from brine electrolysis - by cooling the soln. by releasing it into high vacuum, to ppte. salt crystals

摘要

Method comprises releasing it into a high vacuum region, the vapour thus sepd. being condensed by the same soln. which has undergone a complementary cooling and a sepn. of pptd. crystals. A large part of the cooling is thus effected without heat exchange surfaces and hence without risk of encrustation. The caustic soda mother liquor then reheats. complementary cooling may be effected by injection of liquedified gas.