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steam is obtained by heat addition (boiling) and pressure reduction (flashing). The
evaporation-condensation process is carried out in closed chambers (stages).
seawater enters the low-pressure area. these areas are known as Flush Vessels. The
function of a flush vessel is to create a sudden low-pressure area, this case to sudden
evaporation for hot seawater because of the sudden pressure drop.
The vacuum in the flash vessel is achieved by a steam ejector driven by high-
pressure steam or by a mechanical vacuum pump or by orifice plat.
After that, steam is packed in pipes, then the hot steam condensed by heat exchange
with cold income seawater and collected in freshwater tanks. To improve the
capacity of MSF, multi-stages of flush vessels are used.
Figure 2.7 single-stage MSF.
A demister is used in MSF to separate water droplets from steam by coalescing
smaller liquid droplets by obstructing their path by a demister pad.
Figure 2.8 demister work principle
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