Principle of freeze drying
Freeze drying is a method of freezing a water-containing substance into a solid state and then sublimating the water in it from the solid state into a gaseous state to remove the water and preserve the substance. In the process of compressed air drying, freeze drying is to reduce the temperature of the compressed air so that the water in the compressed air is precipitated. The working principle of the freeze dryer (cold dryer) is the same as that of a refrigerator. After the compressed air passes through the frozen compressed air pipeline, the temperature of the compressed air drops to the required temperature to meet the drying requirements. The substances treated by this method have the advantages of not easy to deteriorate, long-term storage, complete dehydration, easy rehydration, and conducive to maintaining the activity of heat-sensitive components and reducing the loss of volatile components. Drying at low temperature does not change the substances that need to be freeze-dried during the drying process, and maintains the original biological activity. Drying is carried out under low pressure, so that the easily oxidized substances are protected. At the same time, the low temperature and lack of oxygen can sterilize or inhibit the activity of certain bacteria, thereby keeping the properties of the product unchanged. Drying at low temperature can reduce the denaturation of heat-sensitive products, increase the surface area of freeze-dried products, and have good solubility and rapid rehydration.
Multipurpose vacuum freeze dryer
Freeze drying technology has a wide range of applications in modern bioengineering, pharmaceutical industry, food industry, materials science, deep processing of agricultural and sideline products, chemical engineering and other fields.
Processing vacuum freeze drying technology in special food applications has been widely used in field operation foods such as aerospace, navigation, mountaineering, and exploration.
In the field of special biotechnology products, freeze drying technology is mainly used for the production of serum, plasma, vaccines, enzymes, antibiotics, hormones and other drugs; biochemical test drugs, immunology and bacteriology test drugs; long-term preservation of blood, bacteria, arteries, bones, skin, cornea, nerve tissue and various organs.
In recent years, in the chemical industry, various materials used as catalysts have been well used in freeze drying.
Large freeze dryer and freeze-dried batch production
The current status and development of equipment The application of freeze-drying technology is inseparable from the equipment. So far, the forms of freeze-drying equipment are mainly divided into two categories: intermittent and continuous. The scale of equipment ranges from less than one square meter to more than 200 square meters. Intermittent freeze-drying equipment Intermittent freeze-drying equipment is suitable for small-batch production of multiple varieties, especially in the food field for seasonal food production. Single-machine operation is adopted. If one equipment fails, it will not affect the normal operation of other equipment. Intermittent freeze-drying equipment is convenient for controlling the heating temperature and vacuum requirements at different stages of material drying. The processing, manufacturing and maintenance of the equipment are easy to carry out. However, since operations such as loading, unloading, and starting take up a lot of time, the equipment utilization rate is low and the production efficiency is not high. The characteristics of continuous equipment are that it is suitable for the production of products with a single variety and large output, a large market share, and sufficient raw materials. In addition to being suitable for the production of freeze-dried strawberries, freeze-dried lemons and other vegetables, fruits, etc., it is also particularly suitable for the production of various chemical raw material slurry and granular additive products. Continuous equipment is easy to realize automatic control, which simplifies manual operation and management. In the future, how to improve freeze-drying efficiency, shorten drying time and save energy while ensuring product quality will be the goal of most freeze-drying industry workers.
