Flow characteristics of air separation in VPSA process with radial flow adsorber

Radial flow adsorbers are widely applied to large-scale air separation. The low pressure drops and flow uniformity in radial flow adsorbers (RFAs) are of great importance for high quality O2 enrichment. However, the insufficient consideration of annular channel structure and simplification of perforated plate distributor in existing methods limit a further optimization of uneven flow in the RFAs. In this study, the detailed perforated plate distributor configuration (hole arrangement and porosity) is adopted to investigate the flow field in the RFAs more deeply. In addition, the effects of three types of annular channels on pressure drop profiles rarely studied intensively in previous publications are also discussed. The simulated results agree well with static and dynamic experiments in terms of N2 adsorbed amount and breakthrough time, indicating the feasibility of proposed model for RFAs simulation. Thereafter, it can be found that for the adsorber with a convergent annular channel, the utilization ratio of the adsorbent and desorption efficiency can reach up to 27.58% and 91.64% respectively, accompanied by average 96.61% pressure drop uniformity. Moreover, the impact of hole arrangement is insignificant in the case of a regular arranged cylindrical holes on the distributor. However, the nonuniform porosity makes the adsorption area shift from the bottom to upper of the adsorber by changing the flow resistance. For the adsorber with convergent annular channel and optimized arrangement of distributor, the whole flow uniformity can be improved by 24.69%.