Vacuum drying is a process of indirectly heating a material under a condition of lower than normal pressure, and vaporizing the moisture in the material at a corresponding temperature to reduce the moisture content in the material. The vacuum drying process involves three processes. The heat is transferred from the heat source to the material, causing it to heat up and vaporize the moisture, a so-called heat transfer process. The vaporized moisture vapor migrates to the drying chamber space, so that the moisture vapor is separated from the surface of the material and discharged into the drying chamber, that is, the so-called moisture vapor mass transfer process on the surface of the material. The moisture inside the material migrates to the surface of the material in a liquid state to facilitate vaporization on the surface, the so-called wet internal liquid mass transfer process. It can be seen that vacuum drying is the three processes involved and coordinated, and the coordination of good and bad directly affects the vacuum drying speed and the quality of its products. To complete the above heat and mass transfer process, the following three conditions must be met. The heat transfer is carried out by the temperature difference between the heat source and the material, and the latent heat of vaporization of the heat and moisture is provided for the material, that is, the so-called temperature condition. The gas mass transfer of the moisture content of the material is carried out by the moisture vapor pressure difference between the surface of the material and the drying chamber space, that is, the so-called pressure (or vacuum) condition, so it is necessary to ensure that the steam pressure of the moisture component on the surface of the material is higher than that of the drying chamber space. Partial pressure. Relying on the difference in the concentration of moisture inside the material, the moisture is transferred to the inside of the material for liquid mass transfer, the so-called concentration condition. Optimizing the above three conditions and combinations thereof can increase the vacuum drying speed and the quality of the products. In the vacuum pump drying equipment, the heat energy required for drying the material is transmitted by heat conduction and heat radiation between the heat source and the material. The heat transfer in the vacuum drying equipment is different from the temperature coefficient of its structure, material and surface tension, and the material is changed. The method of drying the temperature to increase the capillary driving force. The general vacuum drying techniques and equipment described here do not include vacuum freeze drying, vacuum vapor drying, and vacuum high-intensity drying using microwave, laser, and electron beam heating sources. Due to the different materials to be dried, the requirements for dry products are different. Different vacuum drying equipment should be selected, and different drying processes and their parameters should be adopted. When selecting a vacuum drying equipment, the following factors should be considered when determining the vacuum drying process and its parameters. The viscosity of the material of the material to be dried and its variation with the moisture content; the adhesion of the material during drying; the moisture content of the wet material; the particle size of the material and its requirements for the pulverization ability. The allowable temperature of the material to be dried and its rate of temperature rise. Requirements for bulk density and filling rate of materials to be dried. The form of motion of the dried material in a vacuum drying device and its parameters. Dehumidification rate, ie the requirement of drying speed. The particle size and quality of the dried product, whether the moisture content to be removed requires recycling or the like. For example, the dry product has a small particle size and a light weight, and the trap should be equipped with a trap to collect the dried product in the drying equipment; if the removed moisture is classified into an organic solvent, the condenser must be configured to recover the moisture. During the drying process, the degree of vacuum is related to various factors such as drying temperature, drying speed, equipment structure and performance, composition of the pumping system, and pumping performance. Therefore, the degree of vacuum is not only an important basis and consideration for selecting equipment and determining the process, but also one of the core process parameters that must be strictly monitored and adjusted at any time during the drying process.