Forced air evaporators often employ a packed tower and air blown in the opposite direction to the flow of liquid to reduce energy requirements and improve evaporation efficiency. However, energy reduction is limited and there is still often the potential for release of hazardous emissions to atmosphere.

Vacuum evaporators boil off liquids in an enclosed vessel or “kettle” which is operated under low negative pressure (30-80 mbar). By operating under vacuum the vapour pressure of the liquid within the kettle is reduced, allowing the liquid to boil at lower temperature.

For example, in a typical vacuum evaporator water will boil at 40 deg. C rather than 100 deg. C when at atmospheric pressure. As a result, energy requirement is dramatically reduced.

At atmospheric pressure, approximately 0.62 kW of energy are required to transform 1 litre of water into steam (this does not account for any inefficiency in the boiling process). In our vacuum evaporators this energy requirement is reduced to around 0.15 kW per litre, a significant reduction.

By boiling off liquids in an enclosed vessel and operating a dedicated condenser the potential for hazardous emissions is also removed.