Discussion
• In Part a, the temperature of the thin liquor fed to the evaporator is less than the boiling temperature so part of the steam energy is used to heat the feed to the boiling temperature. This amount of heat is the heating load. In Part b, the temperature of the feed is greater than the boiling temperature. The steam requirement is reduced since some heat is brought in by the feed above its boiling point in the evaporator. This quantity of heat is the flash evaporation.