Vacuum distillation is a vacuum process often used in various chemical, pharmaceutical and petrochemical enterprises. At present, more and more enterprises fall in love with screw vacuum pumps in the process of selecting vacuum pumps for vacuum distillation, from chemical enterprises to various pharmaceutical enterprises. Recently, a well-known domestic pharmaceutical enterprise added another 18.5kw dry screw vacuum pump for vacuum distillation. With the improvement of social quality requirements for various industries, product defects will be amplified and the tolerance will be lower and lower. This is especially true for pharmaceutical products. Therefore, in vacuum distillation, in order to improve the distillation efficiency and improve the quality of distillation products, more and more pharmaceutical enterprises no longer pay attention to the pumping speed and vacuum degree, but also pay attention to the improvement of product quality by clean vacuum in the process of vacuum pump selection. The working range of dry screw vacuum pump is from atmospheric pressure to about 1pA extreme vacuum. It has a wide range of large pumping speed. A single pump with low vacuum can achieve high pumping speed. It has simple and reliable structure and convenient maintenance and operation. On the other hand, due to the inherent cleaning characteristics of screw vacuum pump, there is no need for other media to participate in the extraction process, and there is no need to worry about backflow polluting media. Moreover, it can be combined with roots to form a dry vacuum unit product with clean, high vacuum degree and large pumping speed. In food, fine chemicals, pharmaceutical semiconductors and other fields with strong demand for clean vacuum and various recycling fields, these characteristics can effectively improve the production efficiency of enterprises, greatly simplify the operation process and various supporting links of vacuum system, and improve the product quality. Therefore, they are favored by enterprises.