Multistage flash distn. plant - using flash evapn. process and direct contact heat exchange for condensers; used for prodn. of sweet water from salt or brackish water

摘要

Multistage flash distn. plant comprises a feed preheater, a vertical tower including a stack of intercommunicating evapn. chambers and an opening in the top of the tower supplied with preheated feed from a feed preheater. Around the vertical stack is an annular row of ducts and a series of interconnected superimposed direct contact annular condenser chambers, each disposed around the annular row of ducts. Each evapn. chamber has a vapour outlet which communicates via one of the ducts with a condenser chamber. The uppermost condenser chamber is connected to a supply of condensing medium. The bottom evapn. chamber has an outlet for concentrate and the bottom condenser chamber has an outlet for condensate. Used for distn. of salt or brackish water to produce sweet water. The plant is constructed in reinforced concrete, the several chambers and conduits being built into a concentric area of a vertical cylindrical shell. Heat exchange surfaces, which are liable to corrode, are avoided by adopting flash evapn. for the evapn. process and direct contact heat exchange for the condensers.