CHAPTER
Selected Definitions Evaporation: Evaporator:
It is the process by which liquid water goes directly to the vapor phase due to an increase in temperature. It is an equipment in which liquid is boiled.
Economy of an evaporator: Triple evaporator:
It is expressed as quantity of vapour produced when one unit steam is supplied.
It consist of three evaporators.
Jacket: It is defined as casing or envelope with outer pan.
5.1 INTRODUCTION Evaporation is the process by which liquid water goes directly to the vapor phase due to an increase in temperature. The main objective of evaporation is to get a concentrated product by vaporizing volatile liquid. Evaporators are generally used to carry out the evaporation process. Evaporation is conducted by non volatile solute and volatile solvent to produce thick liquor. Rate of evaporation is controlled by rate of heat transfer. When heat is applied in solution, the movement of the molecules increases and the molecules present in the surface overcome the surface tension of the liquid and evaporate because the surface molecules have less cohesive force than the others. Evaporation differs from distillation because in distillation vaporization take place at the boiling point while in evaporation vaporization take place below the boiling point.
5.2 OBJECTIVES OF EVAPORATION Evaporation is done 1.
To get concentrated product
2.
To remove water from aqueous solution
3.
To evaporate seawater for developing drinking water
4.
To get solid free water which is used in boilers for chemical processes.