Condensate Flash Vessel

The Multiple Effects Evaporators operate with reducing pressure from first to last effect. The condensate temperatures also vary in similar fashion. When higher temperature condensate is introduced in the lower pressure effect, it loses its heat content and some steam is produced which is called as flashing. This flash steam can be used for heating in the evaporator for heating. This additional amount of heat recovered from the condensate reduces the amount of exhaust in first effect.
The exhaust condensate is approximately at same temperature of exhaust steam. Normally exhaust condensate is sent to the feed tank at boiler station for regeneration of steam. The excess heat associated with this condensate is flashed to atmosphere since the feed tank is normally vented. This waste heat is recovered by suitable heat exchanger, which reduces the equivalent quantity of exhausthigh pressure steam.