Evaporator and Evaporation. Purpose and applications of evaporation.

 

Evaporators

A device that is used to convert liquid into gaseous form (vapors) by heat transfer.

Evaporation

Evaporation is a process in which the removal of water takes place by boiling the liquor.

Purpose of evaporation?

•   To increase the concentration of liquid.

•   Evaporation is not only used for the concentration of liquor it is also used to generate vapors and to recover solvent.

How to recover solvent?

In evaporation, the solvent is converted into vapors. Vapors of solvent are comparatively pure because impurities did not evaporate. By condensing these vapors we can get pure solvent. This recovery solution can be used for further different methods.

Applicationof evaporation:

•   For the preparation of liquor for the next unit operation.

For example; Drying and crystallization.

For example; In the sugar industry, where crystallization takes place. Before crystallization evaporation takes place.

•   To reduce storage cost.

•   To reduce transport costs.

When liquid is in dilute form, its volume is greater. So the transfer of this liquid from one place to another place is costly. But when liquid is concentrated its volume decrease, and the transportation cost also decreases.

Example of transferring liquid:

Many industries did not install their effluent treatment plants (ETP) to treat their waste liquid before its drainage into the seas. They transfer their waste liquid after evaporation to the centralized effluent treatment plant.

•   To concentrate liquid.

For example; the Preparation of condensed milk.

For concentration of juices and jams.

For pharmaceutical products.

For concentration of NaOH and NaCl to produce salt from an aqueous solution.

•   For solvent recovery.

For example; Desalination. Desalination is the process to convert seawater into useful water by evaporation. In this case, the main product is vapors, not concentrated liquor.

Ether recovery from fat extraction.