These two materials are widely used in air separation equipment. Stainless steel is usually used in the environment with constant temperature or corrosive substances in the tower, while aluminum is used in the environment with constant temperature, such as the lower packing of air cooling tower, stainless steel is used, and the tray of main tower is made of aluminum.

Aluminum has good strength and toughness and good thermal conductivity at low temperature; aluminum fins are used in the main heat exchanger, which is easy to weld with aluminum; aluminum is also easy to cut and install, and most importantly, it is cheap. However, stainless steel is generally used in liquid air, which has better strength, life and safety than aluminum. Bimetallic joints of aluminum and stainless steel will be more used. I think if it is the internal compression process with high working pressure, it is better to use stainless steel.