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Structural characteristics of molecular distillation equipment

1. Install a condenser inside on the basis of the scraper evaporator. When the feed mixture is heated, the molecules of a light substance move to a certain distance when they encounter the condenser, they are condensed into liquid and separated, and the heavy substance flows down the wall. Because the vapor phase of the light material is condensed inside, the vacuum pressure drop is small and the high vacuum in the equipment can be maintained.

2. Extremely high vacuum: The special structure design of short-path distillation allows the operating pressure to reach a very low operating vacuum. The vacuum of the experimental scale equipment can reach 0.1Pa, even the industrial scale equipment can reach 1-5Pa.

3. The operating temperature is much lower than the boiling point of the material: Because the short-path distillation uses central condensation, the cross-sectional area of the material flow is equal to the evaporation surface, so that there is only a slight pressure drop between the evaporator and the condenser, that is to say, the vacuum at the end of the vacuum system Almost close to the vacuum of the evaporator. The extremely low working pressure ensures extremely low distillation temperature, so short-path distillation is currently the mild distillation method.

4. Features of molecular distillation equipment: The separation of the mixture is achieved due to the different nature of the mean free path of different types of molecules escaping from the liquid surface, and does not need to be completely boiling, so the actual evaporation temperature of the material in the evaporator is slightly lower than the empty The theoretical boiling point of the material under the following conditions. This is fundamentally different from distillation.

5. Short heating time for short-path distillation: By adopting the design of vertical scraper to form the film, the residence time of the material on the heating wall is short. For other distillations, the heating time is generally longer (more than 30 minutes or even dozens of hours). The short-path distillation is only ten seconds. Due to the strict distance requirements between the heating wall of short-path distillation and the condenser, light molecules escaping from the liquid surface reach the condensation surface almost instantaneously, and the heating time of the vapor phase light molecules can be ignored in this process. The possibility of thermal decomposition is minimized.

6. Superior mass and heat transfer efficiency: The short-path distillation adopts a mechanical scraping film system, which is different from the uneven film formation defects of other falling film evaporators. The film thickness of the material in the short-path evaporator is uniform and the flow characteristics are excellent. The area of the liquid surface and the heating surface are almost equal, and the mass and heat transfer efficiency is superior.