| Pressure swing adsorption (PSA) is a process where one or more fixed beds are used to separate a gas mixture based on the differing affinities of individual components for a selected adsorbent. The process is widely used in industry for drying, landfill gas separation, and air separation. Recently, PSA has been used in smaller, portable units that generate enriched oxygen streams from air feeds aboard aircraft and for medical use. This work has focused on the design and operation of small-scale PSA air separation systems through laboratory experimentation and mathematical modeling.;Feed rates and product gas compositions were measured as functions of time for experiments using different sized dual-bed PSA units on two adsorbents. Feed pressure, product flow rate, feed composition, and cycle time were varied in these experiments.;The data were compared to predictions from an isothermal, first principles mathematical model for the PSA system. A constant coefficient linear mass transfer driving force approximation was used to model nonequilibrium mass transfer. The mathematical model calculated flows into and out of the beds as functions of bed, supply, and exhaust pressures. The model differs from most of those previously published because it calculates bed pressures instead of requiring bed pressures to be specified in the model beforehand; the model predicts dual-bed PSA system performance rather than simply correlating the data. This feature allows for the a priori design of dual-bed PSA systems, including connecting piping and valves. |
