It’s been a few days now, requirement of Nitrogen, Oxygen and Argon increases day by day. Especially for a steel industry this three components are very essential for their steel production like decarburization, desulphurization, hydrogen removal, nitrogenation, argon, oxygen removal, metal cutting, welding, and cooling etc. Cryogenic air separation has the best impact to separate the air. Study and analyses of practical plant performance through computer aided programs has better and cost effective. Aspen Hysys by Aspen Technology is one of the major process simulators that are widely used in cryogenic, chemical and thermodynamic process industries today. In this work, the simulation study of cryogenic air separation unit (Rourkela steel plant, Odisha) is performed by using Aspen Hysys. The simulation study is based on both steady state and dynamic (high pressure column and low pressure column). The dynamic air separation unit has been designed based on PI controller. The plant efficiency, specific power consumption, product purity and behaviour of process parameter with respect to time and feed disturbance have been discussed
