Operating principle of short path distillation unit (SPDU) is similar to thin film evaporator except internal condenser. Here internal condenser is installed inside rotor cage assembly. The feed enters the unit at top and get distributed into a thin film on the inside surface of shell. Heating medium passing through the jacket evaporates volatile component in feed. The vapor generated flow across the rotor and condense on internal condenser. This short path of vapor eliminate pressure drop. Hence evaporation can be done at high vacuum as 0.001 mbar(a). The distilled product and balance bottoms are taken out through separate outlets.