Large cryogenic air separation unit

1. Before connecting the pipe orifice of each container, clean white cloth shall be used to tie the orifice to prevent grease and dirt from entering. 2. When welding in the cold box and in the condensing evaporator, it is strictly forbidden for flame or arc to touch the surface of vessels and pipes. 3. The containers, valves, pipes and corresponding supports in the cold box, the surface of the cold box and the foundation surface shall not be stained with grease after installation, otherwise, degreasing treatment shall be carried out.

When the amount of processing air is reduced, the rising steam and reflux liquid in the upper column will be reduced, but the reflux ratio will not change. Therefore, the reduction of processing air in a small range will not affect the purity of oxygen and nitrogen, and the reduction of processing air volume will help to reduce the pressure of the upper and lower columns. However, according to the material balance, the production of oxygen and nitrogen will naturally decrease when the amount of processing air is reduced. If the amount of processing air is too small, there will be leakage on the tray. If the heat and mass exchange of the leaked liquid is not sufficient, the purity of oxygen and nitrogen will be greatly affected, and even the normal production can not be realized. Therefore, the minimum allowable load of distillation column is generally specified.