Vacuum freezing dryer lyophilization principle of freeze-drying process is also the sublimation of liquid water, water has three kinds of state of aggregation, namely, liquid, solid and vapor.
Based on the theory of water balance of three phase, the three-phase point of water (
Steam, liquid and solid phase coexistence)
The temperature of 0.
0098 ℃, the triple point pressure for 609.
3Pa。
Vacuum freeze drying was conducted under the triple point, lyophilization is used when the pressure is lower than the triple point, ice crystals absorb heat directly into the principle of steam steaming, the fresh material in vacuum freezing dryer in low temperature freezing, under high vacuum condition, use the sublimation of water features, make the moisture in the material, not after the melting of the ice, directly in an ice sublimation, for water vapor is removed, so that the material to achieve the purpose of freeze-drying.
vacuum freeze drying, the heating plate temperature, material temperature, condenser temperature and vacuum drying storehouse in all change with time, any link or several links can be drying process & other
Bottleneck & throughout;
。
In order to ensure the feasibility of the freeze-drying process, processing of qualified freeze-dried products, in the process of freeze-drying, the products and board layer temperature, condenser temperature and vacuum control time drawn into curve, called freeze-drying curve.
The same product use different freeze-drying curve, the quality of the product is not the same;
Different products, different vacuum freezing dryer and frozen material characteristics and operating conditions of the different applications of different freeze-drying curve.
Even with the qualified products, but also to analyze the data, provide the basis for further optimization.
Select the appropriate freeze-drying curve is the key of the freeze drying process.
