Vacuum Dryer
The working process of the vacuum dryer is to place the material in a sealed cylinder, and heat the material continuously while the vacuum system is evacuating the vacuum, so that the moisture inside the material diffuses to the surface through the pressure difference or concentration difference. The water molecules obtain enough kinetic energy on the surface of the material, and after overcoming the mutual attraction between molecules, they escape to the low-pressure space of the vacuum chamber and are then pumped away by the vacuum pump.
Vacuum drying principle
●During the vacuum drying process, 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. Therefore, it can dry materials that are easily oxidized and deteriorated, flammable and explosive, etc. It can play a certain role in disinfecting and sterilizing medicines, foods and biological products, and can reduce the chance of material contamination or inhibit the growth of certain bacteria.
●Since the temperature of water is proportional to the steam pressure during the vaporization process, the moisture in the material can be vaporized at low temperature during vacuum drying, and low-temperature drying can be achieved. This is beneficial for the drying of heat-sensitive materials in some medicines, foods and other products. In addition, drying at low temperature has a reasonable utilization rate of thermal energy.
●Vacuum drying can eliminate the surface hardening phenomenon that is easy to occur in hot air drying under normal pressure. This is because the pressure difference between the inside and the surface of the material is large during vacuum drying. Under the action of the pressure gradient, the moisture quickly moves to the surface and no surface hardening occurs. At the same time, it can increase the drying rate, increase the drying time, and reduce the equipment operation cost;
●Because the temperature gradient between the inside and outside of the material is small during vacuum drying, the reverse osmosis effect allows the solvent to move and collect independently, effectively overcoming the solvent loss phenomenon caused by hot air drying. Only vacuum drying can achieve the true recovery of solvents and has an environmental protection effect.
How does vacuum drying work
The vacuum dryer reduces the boiling point of the material under vacuum, thereby improving the drying efficiency. Compared with conventional drying methods, vacuum drying can be carried out at a lower temperature, is suitable for heat-sensitive materials, and can effectively avoid thermal damage and oxidation.
The basic working principle of the vacuum dryer is to use a vacuum pump to extract the air in the drying chamber to form a vacuum state. In such an environment, the evaporation temperature of water is reduced, and the water in the material can be evaporated faster. In order to improve the drying efficiency, the equipment is usually combined with other heating methods, such as jacket heating, radiation heating, etc.
