The drying of apparatus is usually the chemical drying method.
Chemical drying method is the appropriate desiccant added directly to the liquid to be dried, so that the liquid and the role of water to achieve the purpose of drying. According to the principle of its role in different desiccant can be divided into two categories: one is the formation of crystalline water inorganic salts, such as anhydrous calcium chloride, anhydrous magnesium sulfate, anhydrous sodium carbonate, etc.; the other is the water can be chemically reactive substances, such as sodium metal, phosphorus pentoxide, calcium oxide, and so on.
The former class of water absorption is reversible, temperature that is released water of crystallization, so in the distillation before the desiccant should be filtered out, the latter class of role is irreversible, in the distillation can not be filtered out. For a specific drying process, the factors to be considered are the type of desiccant, dosage, drying temperature and time and drying effect of judgment. These factors are interconnected and mutually restrictive, and therefore need to be considered comprehensively.
Other drying methods
1, atmospheric pressure drying
that is, in an atmospheric pressure condition of drying is called atmospheric pressure drying, atmospheric pressure drying method is the most widely used, the operation as well as the equipment are simple, and has a fairly high accuracy.
2, decompression drying
Decompression drying is in a closed container after vacuum drying method, the advantages of this method is lower temperature, the product is loose and easy to crush. Temperature rise, can speed up the evaporation rate, increase the evaporation, is conducive to drying. However, depending on the nature of the drying material should be appropriate to choose the drying temperature, in order to prevent the destruction of certain components.