Optimal Dynamic Operation of a High-Purity Air Separation Plant under Varying Market Conditions

In the air separation industry, distillation-based cryogenic separation is the dominant technology for large-scale production of high-purity nitrogen, oxygen, and argon products. The use of rigorous dynamic models in the design and operation of air separation units can provide insights into the plant operation to inform the development of economically beneficial designs and operating practices. In this study, we provide a comprehensive analysis on a liquid storage and vaporization strategy for air separation units following a two-tiered multiperiod formulation with a collocation-based dynamic model. Economic incentives for collecting liquid, either directly as liquid product or by liquefaction of overproduced gas product, and then redistribution for meeting gas product demand or for use as additional reflux are explored in a transient market environment. This includes different electricity price and/or demand profiles, operation costs, as well as product specifications. Operation bottlenecks due to process dynamics constrain the operation practice and hence influence the potential profitability.