TWO STAGE FLASH EVAPORATOR

The sea water pumjD_tsupplies water which divides into two flows, one to the air ejector (maintains vacuum, extracting air and other non-condensibles) and the other to the main circuit.

In the main evaporator sea water circuit, the water is the coolant in the condenser and it then flows to the main heater.

The heated sea water is admitted to the first flash chamber, wh#s& a quantity of it is flashed off into vapour, this vapour is drawn to the condenser and is condensed. The dilute brine from first stage chamber is drawn into second stag^ flash chamber where a further quantity flashes off.

The vapour condensed in both condensors is extracted by the distillate pump.

In cold sea water condition some of the brine can be recirculated (if a brine pump is used) to heat the sea water feed to the main heater.

The vacuum differential between stages is maintained by orifice plates in the air, distillate and brine interstages.

The main advantage of the evaporator is that the heating process is a sensible heat non-boiling process and is applied only ta sea water not brine.

Multi stages of flash can be used, cruise ships have used up to five stages.

2 STAGE FLASH EVAPORATOR                                                                              

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