PRINCIPLE / THEORY:
Evaporation is a unit operation where in the solution is concentrated by removal of solvent, namely water. It differs from drying in that the end product is a solid rather than a liquid. It differs from distillation in that the end product is concentrated solution rather than a vapor. When a liquid surface is open to atmosphere, concentration gradient is set in between the liquid surface and atmospheric air. At the liquid surface, the partial pressure of vapor will be equal to vapor pressure of liquid at the surface temperature; the partial pressure of the vapor away from the liquid surface is determined by water vapor present in the atmosphere. The performance of any evaporator is governed by two factors,
Capacity and Economy
1. Capacity is defined as the amount of water evaporated /hr.
2. Economy is the amount of water evaporated /kg of steam.
Steam consumption is defined as: Capacity / Economy.
Vaporization efficiency is defined as:
Heat supplied per evaporating a fixed amount of water /Theoretical amount of heat required.
EQUIPMENT USED:
Steam heated boiler, Water Cylinder, pan, and temperature indicators.
MATERIALS USED: Water / Milk can any liquid for study
EXPERIMENTAL PROCEDURE:
OPEN PAN EVAPORATOR
1. The diameter of the vessel is measured.
2. Steam boiler is started and pressure is developed.
3. 0. 5 liters of milk is measured and poured into the pan.
4. Steam is allowed by opening the valve and steam pressure is adjusted to (0.5 to 1. kg/cm2) and stop clock is started.
5. The evaporation is continued till 80% of the liquid is evaporated and milk gets concentrated.
6. The boiling temperature of milk is noted down.
7. Steam supply is started and boiler is switched off.
8. The concentrated milk is collected and weighed.