Abstract: At present，tube evaporation system was universally adopted in China′s akali sulphide industry，but most akali sulphide manufacturers complained there was liquid leakage phenomenon while using it.Based on the existing problem，the evaporator′s structures，such as dimensions of evaporator chamber，form of demister，location of incoming port and outlet position of circulation tube，were analyzed.In addition，the evaporation system′s control conditions，such as vacuum degree，feed rate，evaporation bottom liquid，and evaporation concentration，were discussed and the reasons of liquid leakage were found.Finally，concrete measures from the aspects of equipment structure design and process conditions were put forward.

Key words: sodium sulfide, evaporator, liquid leakage