The so-called vacuum distillation is to vacuum the system, thus reducing the evaporation temperature, but for thermosensitive substances, in the distillation 釡 vacuum distillation has a lot of defects. For example, it takes a long time for distillation; the vacuum pump is difficult to overcome the hydrostatic pressure of the liquid surface in the distillation kettle, so the distillation kettle is replaced with a thin film evaporator.
If vacuum distillation is carried out in a thin film evaporator, it can evaporate from a thin film to eliminate the effect of high hydrostatic surface, and the material flows down the heated cylindrical cylinder to form a film, and the material in the flow process is evaporated.
What would be the effect of adding a condenser to the outside of the film evaporator? The liquid film is continuously mixed with a film scraping system, condensing in an external condenser, and the condenser is connected with a vacuum system, which is vacuum distilled in such a way that there is almost no liquid surface pressure difference, which reduces the loss of vacuum.
But the film evaporator with outer condenser also has limitation, because the pressure drop caused by the connection between the evaporator and the condenser is limited, so the vacuum degree obtained in the evaporator is restricted to the level of the MB. It may be possible to change the external condenser into a built-in condenser, so that it can completely eliminate the disadvantage of insufficient vacuum, there is no pressure drop problem.