The process of the freeze dryer is mainly divided into two stages, one is the freezing stage, and the other is the vacuum stage (also called the drying or sublimation stage). Many people think that the lower the freezing temperature and the vacuum in the drying stage, the better when using a freeze dryer, but this is not the case.
The characteristics of each material are different, so their crystallization points are different. The freezing temperature and water capture temperature in the freezing stage of the freeze dryer are mainly determined according to the characteristics of the material itself, not the lower the better, and the temperature is too low. Waste energy, and secondly prolong the time of materials in the freeze dryer.
The drying stage can be further divided into pre-drying, primary drying, and secondary drying. The application of each stage and the degree of drying that can be achieved depend primarily on the drying process.
The pre-drying of the freeze dryer refers to the first stage of drying that mainly removes free moisture; the primary drying of the freeze dryer refers to the drying stage that mainly removes free moisture, and the first drying can only be carried out in a vacuum; the second drying of the freeze dryer Refers to the drying stage from freeze-drying to complete removal of moisture contained in the solid polymeric state.
