Chapter 6 - Multi-Stage Flash Desalination

Abstract

This chapter analyzes and evaluates the performance of the multistage flash desalination (MSF) system. This is made through a discussion of the process developments of MSF; standard features of the brine circulation MSF process; modeling and analysis of the single stage flashing system, the once through multistage system, and the brine circulation multistage system; and features and performance of novel configurations, which include MSF with brine mixing and MSF with thermal vapor compression. The MSF process is an innovative concept, where vapor formation takes place within the liquid bulk instead of the surface of hot tubes. The chapter also presents a novel system for the multi-stage flash desalination. The system is based on the conventional MSF configuration. It includes two of its basic elements; the brine heater and the heat recovery section. The cooling water stream, typical of the MSF system, is also eliminated. The new system adopts a direct brine recycle stream from the brine stream leaving the last flashing stage. This stream is mixed with the intake seawater stream in an insulated and vented tank. Accordingly, the temperature of the feed stream is adjusted to meet summer and winter operating conditions.