Essential oils are highly heat sensitive, as such distillation and fractionation is to be carried out at low temperatures and sub-atmospheric pressures. In case of fractionation, vacuum pumps are used for this purpose, while as in case of steam distillation, pressure lowering effect is achieved by lower partial pressure of the feed components, enabling vapourization at sub-atmospheric conditions
Lemon grass (chopped or unchopped) is filled in the distillation still and its lid is fitted tightly by swivel bolts, so that oil and vapour do not leak out. The steam is injected in the still by the help of steam spargers provided at the bottom of the vessel.
The upcoming steam carries away the oil from the plant material i.e. lemon grass and both oil as well as steam pass to the condenser through vapour line, where these vapours get condensed and oil and water are separated in the separators. Oil being lighter is separated out from the top and water being heavier is taken out from the bottom of separators.
Crude essential oils are obtained by steam distillation of variety of natural products like plants, grasses, wood stumps, sawdust, flowers, kernels and seeds. These oils have played an important role in the personal and social hygiene of mankind in terms of their use in cosmetics, toiletries, medicinal formulations, aroma therapy, surface coatings, etc