Evaporators

EVAPORATORS

An evaporator is a shell and tube heat exchanger where the steam is normally in the shell and the product is in the tube and in motion. Depending upon the type of product and the desire results, more than one stage or effect of evaporation may be required. The triple effect is the most common, although as many as five to six are also used in some applications.

Evaporators are based on steam economy i.e. kg of solvent evaporated per kg of steam used. Reusing evaporated solvent as heating medium, higher steam economies are achieved.

FORCED CIRCULATION EVAPORATORS

These types of evaporators are recommended for the concentration of high viscosities solutions/slurries which have a tendency to crystallize or

produce scales.

The circulating product is heated when it flows through the heat exchanger and then partially evaporated when the pressure is reduced in separator. The liquid product is typically heated only a few degrees for each pass through the heat exchanger.

This type of evaporator is also used in crystallization applications because no evaporation and therefore no concentration increase, takes place in the heat transfer surface. Evaporation occurs as the liquid is flashed evaporated in flash vessel/separator.

Advantage:

· Ideal for high crystallizing and high viscosity solutions & Slurries.

· Single or multiple effect evaporation

· High operational flexibilities, heat transfer co-efficient, vapours liquid separation.

· Low temperature rise operation.

· Minimized fouling due to high velocities & static head.

· High turn down ration.

Comments

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