Working Principle of Short Path Distillation
Short path distillation is a continuous distillation process that performs separation operations under high vacuum. The distance between the heating surface and the condensation surface of the short-path distiller is less than or equal to the average free path of the molecules of the separated material. Therefore, when the molecules are evaporated on the surface of the liquid film formed by the heating surface of the short-path distiller, there will be no collision among molecules. Molecules will move toward the condensation surface without being blocked and will be condensed on the condensation surface. Therefore, short-path distillation is also called molecular distillation.
Properties of Short Path Distillation
Short path distillation can be separated at any temperature as long as there is a sufficient temperature difference between the cold and hot sides. The separation ability of short path distillation is related to the vapor pressure and molecular weight of the separated mixture, which is 0.5 times that of ordinary distillation (M2 / M1).
Advantages of Short Path Distillation
1. The degree of separation is higher than that of traditional distillation. Short path distillation can separate conventional substances that are not easy to separate.
2. There is no boiling bubbling phenomenon in short path distillation. Short path distillation is free evaporation on the surface of the liquid layer, which works under low pressure. Because there is no dissolved air in the liquid, the entire liquid cannot be boiled during the distillation process, and there is no bubbling phenomenon.
3. It is non-toxic, harmless, pollution-free and residue-free, which can obtain pure and safe products. The operation process is simple and the number of equipment used is small.
Features of Short Path Distillation
- Since short path distillation works at a temperature where the high vacuum is much lower than the boiling point, the distillation time is very short. Therefore, short path distillation has become the most gentle distillation method for separating the target product, especially suitable for concentration, purification or separation of high molecular weight, high boiling point substances and organic mixtures with very poor thermal stability.
- At present, short path distillation has been successfully spread in many industries such as food, medicine, fine chemicals and cosmetics.
- In the short path distillation process, molecules escaping from the heating surface fly directly onto the condensation surface, theoretically there is no possibility of returning to the heating surface, so short-path distillation is an irreversible process.