The Alfa ring bulk packing air separation unit made of PP/RPP plastic material is mainly composed of air filtration and compression system, nitrogen compression system, air precooling system, air purification system, air pressurized expansion, fractionation system with Coarse Argon column and liquid storage system. In the air separation unit, the internal compression of liquid oxygen and the expansion of air are adopted, I. E. The booster air compressor + the liquid oxygen pump + the air turbo expander and the reasonable organization of the heat exchanger system are adopted to replace the external pressure process oxygen compressor. The main reasons are: High Reliability, easy operation and maintenance, low investment cost, more reasonable configuration, small footprint, so the air separation unit needs to use some packing and column internals products, Alpha packing is the choice, has the very big superiority and the mass transfer function in the air separation unit.