The pressure difference between the boiling film and condensing surface is the driving force of the stem flow, and the minimum pressure will cause the flowing of steam. Under the 1mbar, the operation requires that there is the shortest distance between the boiling surface and condensing surface. The evaporator manufactured based on the principle is called the short-path distillation.

The short-path distillation (molecular distillation) is equipped with a inside condenser which is opposite to the heating surface, and make the operation pressure reduce to under 0.001mbar. Its relative low boiling temperature is very suitable for the material with heat sensitive and high boiling point.

Basic constitution: the column cylinder is equipped with an external heating mantle, a rotor and an internal condenser. The fixing frame of rotor is precisely equipped with the scratch film and anti-splash device. The internal condenser is placed in the center of the evaporator, and the rotor is between the column cylinder and the condenser.

Distillation process: The material should be added from the top of the evaporator and continuously spread to the heating surface through the material covered on the rotor. Then, the scratch film is capable of scratching the material into a thin and flowing liquid film. During this process, the light molecular exceeded the heating surface form the condense liquid on inside condenser without any collision. Then, the molecular flows along the condenser tube, and discharges through the discharge tube on the bottom of the evaporator. The residue liquid (heavy molecule) is collected on the circular channel under the heating zone, and flows through the discharge tube on one side.