The special absorber unit is a packed column. The air aspirated with the feedstock into the plant has to be evacuated. This air is a carrier of hexane at its saturation vapour pressure. So the exhaust air is cooled first in chilled water vent condenser to a temperature around 20 degree Celsius for maximum recovery by condensation.
After maximum recovery by condensation further hexane content in the exhaust air can be further reduced only by a absorption by intimate contact with chilled mineral oil in specially designed packed column. Thereafter the air is exhausted to the atmosphere with the maximum hexane content and the absorber oil is stripped with direct stream to remove the traces of hexane and send for re-circulation to cold absorber.