Vacuum Distillation Using Wiped Film Evaporators and Short Path Evaporators

Molecular and wiped film distillation employ the basic principles of thin film distillation. Thin film distillation involves the heating of a raw material on a heated tube’s internal surface until the boiling component begins to evaporate. The vapors are then condensed on the low-temperature tubes of a condenser. A basic wiped film distillation evaporator adds an agitated thin film to create a bow wave that increase heat transfer and evaporation efficiency.

Conventional wiped film evaporators place the condenser outside of the heated evaporator surface while short path evaporators place the condenser inside of the evaporator body. This variation in design detail creates distinct differences in short path distillation applications.

Short path evaporators can operate as low as 0.001 mbar, as opposed to conventional wiped film evaporators, which can only be used down to 1 mbar. This reduces the operating temperature in a short path evaporator, thus limiting the heat history and preventing thermal decomposition of products.

Short path distillation is therefore an excellent option for processing thermally sensitive products. Reduced residence time and very low evaporation temperatures subject the product being distilled to minimal thermal stress. For this reason short path distillation (a.k.a. molecular distillation) is widely used in the distillation of high molecular organic compounds, especially in the pharmaceutical, nutraceutical, essential oils, chemical and food industries.

To learn more about how InChem can meet your short-path distillation needs, use our online contact form or call 1-800-331-7721.

Advantages of Advanced Molecular Distillation

thin film distillationMolecular distillation is a distillation process done under high vacuum. The very short distance the vapor travels before condensing ensures minimal to no loss due to surface hold-up of the vapor and is an immediate release from vapor to condenser surface.  This distillation process is classified as short path distillation and is also referred to as molecular distillation due to the minimal vapor/liquid interface. The technique and equipment are typically used to purify substances with low volatility and/or temperature sensitivity.

Molecular distillation is a time-tested method. First developed before the start of the Second World War, it was used to distill natural products which were highly sensitive to heat, such as vitamins. The process was invented in the United States by Dr. Kenneth Hickman.

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