This process is specially for recovering of specific solvents using the technique of lowering boiling point which occur in vapor and liquid form, It is a major pharmaceutical process, a number of new solvents and intermediates used for medicinal use are developed by this method.

Apart from it the same process can be used for oil industries and solvent recovery in the chemicals for costlier solvents, and this allows reuse of recovered materials. Extraction in the form of fractional distillation offers a number of solvents at different temperature and vacuum range.

There are various stages of distillation processes which works in the vacuum range of 680 mm Hg to 750 mm Hg and above for molecular distillation.

Usually high vacuum needs are sufficed by mechanical vacuum booster systems backed with Two stage liquid ring vacuum pumps or dry screw vacuum pumps. Here the number of solvents to be recovered are known so the amount of vacuum needed at different point is anticipated based on the type of solvent.

For achieving a highly pure product the need is a crisp , continuously high vacuum which is achievable with the Dry Booster system but with a disadvantage of high carry over of non-condensable vapors as well as product due to the virtue of high suction range. It can be prevented by putting receiver and catch pots or condensers.

There are certain basic questions to put forward before vacuum selection for Distillation,

What is to be distilled ?

How much distillation to be carried out in quantity ?

Material properties of Mother Liquor and final distillate ?

Is the material property suitable under vacuum distillation ?

How vapour effects vacuum equipment.?