Operation method of wiped film molecular distillationThe scraping membrane

     Wiped film molecular distillation  method has high evaporation efficiency, but the structure is complicated, the vacuum sealing is difficult, and the manufacturing cost of the equipment is high. In order to improve separation/efficiency, multi-stage series use is often required to achieve multi-stage separation of different substances. A phase equilibrium state can be formed between the phase and the gas phase; in the molecular distillation process, molecules escaping from the evaporation surface directly fly to the condensation surface without colliding with other molecules in the middle, and theoretically there is no possibility of returning to the evaporation surface, so The molecular distillation process is irreversible. The monoglyceride molecules are evaporated from the surface of the distillate and immediately cooled to effect separation. Unreacted glycerin and monoglyceride can be separated by molecular distillation.
    A hard carbon or a rotating blade made of polytetrafluoroethylene is disposed in the wiped film type molecular still. The squeegee not only can fully agitate the downstream liquid layer, but also accelerate the renewal of the evaporation surface layer, thereby strengthening the heat transfer and mass transfer process of the material. The advantage is that the thickness of the liquid film is small and flows along the evaporation surface; the residence time of the distilled material at the operating temperature is short, the risk of thermal decomposition is small, the distillation process can be continuously performed, and the production capacity is large.
    The heating temperature is controlled, and the distillation speed is adjusted, usually 1 to 2 drops per second. During the entire distillation process, the thermometer mercury spheres should always have condensed droplets. The temperature at this time is the temperature at which the liquid and the vapor are in equilibrium, and the reading of the thermometer is the boiling point of the liquid (distillate). The flame heated by the wiped film molecular distillation should not be too large, otherwise it will cause overheating in the neck of the distillation bottle, so that a part of the liquid vapor is directly subjected to the heat of the flame, so that the boiling point read by the thermometer will be higher; On the one hand, the distillation cannot be carried out too slowly, otherwise the mercury ball of the thermometer cannot be sufficiently wetted by the distillate vapor to make the boiling point read on the thermometer low or irregular.