A novel pressure swing adsorption (PSA) steady-state process modeling methodology was proposed previously which greatly simplifies simulation of PSA units by using a concept of adsorption efficiency, referred to as bed-state efficiency, similar to tray efficiency in distillation. In theory, the proposed model provides a simple method for the practicing engineer to use for evaluation of PSA processes. The nature of the bed-state efficiency, however, must be elucidated before the model can see widespread acceptance. Using a combination of experimental data and dynamic simulation, an air separation unit (ASU) was investigated to gain intuition into the behavior of the bed-state efficiencies. Insights and guidance from the ASU case were then applied to the modeling of a nitrogen rejection unit (NRU) removing nitrogen from natural gas. The relationship between the bed-state efficiencies, operating conditions, and design parameters will be discussed as well as the potential for a priori prediction of the bed-state efficiency values.
