Analysis of steady state Cryogenic Air Separation unit of Rourkela Steel Plant and simulation of Fixed Bed Adsorption
Separation of Air

Abstract

Atmospheric dry air contains approximately 78% nitrogen, 21% oxygen, and 1% argon plus low concentrations of noble gases like carbon dioxide, hydrocarbons and other impurities. An air separation unit divides atmospheric air into the three pure gaseous components (nitrogen, oxygen and argon). Further separation may be performed on some plants to produce other gases such as krypton, neon and xenon. Other gas components of atmospheric air, such as carbon dioxide, water vapour and hydrocarbons must be removed to ensure safety, product quality and efficient plant operation. Nitrogen, oxygen and argon are used by industry in large quantities and hence termed industrial gases. The current work aim is to simulate the cryogenic air separation unit including adsorber and cryogenic distillation. Simulation of absorber is carried out using ADSIM of Aspen Tech to remove carbon dioxide (CO2) and water vapour (H2O). The breakthrough curves of carbon dioxide (CO2) and water vapour on 5A molecular sieve and activated alumina respectively are found at different Reynolds number. The study helps to find out schedule time adsorber/desorber unit. ASPEN Plus simulator is used to simulate cryogenic air separation into nitrogen, oxygen and argon. The steady-state simulation results (purity) are compared to Rourkela steel plant real data.