Vacuum pump is widely used in the process of vacuum drying. The so-called vacuum drying is a kind of drying method that puts the material under negative pressure and reaches the boiling point under negative pressure through heating properly or makes the material solidify through melting point after cooling. Under the condition of negative pressure, the boiling point of the water in the material decreases with the increase of vacuum degree. At the same time, the water vapor content is reduced by the vacuum pump clearance, which makes the water and other solutions in the material obtain enough kinetic energy to separate from the material surface. Vacuum drying due to negative pressure
Lower isolation of air makes some materials easy to oxidize and other chemical changes in the drying process better maintain the original characteristics, and can also be better protected by injecting inert gas and vacuuming. Common vacuum drying equipment include: vacuum drying oven, continuous vacuum drying equipment, etc.
The process of vacuum drying is to place the dried materials in a closed drying chamber, vacuum the dried materials with a vacuum system and heat them continuously, so that the water inside the materials diffuses to the surface through the pressure difference or concentration difference, and the water molecules obtain enough kinetic energy on the surface of the materials. After overcoming the mutual attraction between the molecules, they escape to the low-pressure space of the vacuum chamber, so as to be true The process of pumping.
In the process of vacuum drying, the pressure in the drying chamber is always lower than the atmospheric pressure, the number of gas molecules is small, the density is low, and the oxygen content is low, so it can dry materials that are easy to oxidize and deteriorate, inflammable and explosive dangerous goods, etc. It can play a certain role in disinfection and sterilization of drugs, food and biological products, and can reduce the chance of material contamination or inhibit the growth of some bacteria.
Because the temperature of water is directly proportional to the vapor pressure in the process of vaporization, the water in the material can vaporize at low temperature during vacuum drying, which can realize low-temperature drying. This is beneficial to the drying of heat sensitive materials in some drugs, foods and agricultural by-products.
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