Masoud Mofarahi

The separation of oxygen and nitrogen from air, as two essential gases with widespread applications in industries such as medicine, petrochemicals, and chemical processes, has always been of high importance. This study employed the Dual-Reflux Pressure Swing Adsorption (DR-PSA) process for the simultaneous separation of these two gases. The primary objective of this research was to optimize operational conditions to achieve the highest purity and recovery of oxygen and nitrogen using Aspen Adsorption simulation software. In this context, the effects of key parameters, including feed or light reflux time (tFE/LR), heavy reflux flow rate (QHR), vacuum pressure (PL), and feed flow rate (QF), on system performance were investigated. After conducting the simulations, the optimal conditions for these parameters were determined to be 60 seconds, 0.3 m³/h, 4 bar, and 0.3 m³/h, respectively. Additionally, under these optimal conditions, the performance of two zeolitic adsorbents, LiLSX and 13X, was compared. The results indicated that the LiLSX adsorbent achieved purities of 99.4% for oxygen and 99.2% for nitrogen. The recovery rates for oxygen and nitrogen were 98.5% and 95.5%, respectively. Furthermore, the oxygen productivity with LiLSX was 0.556 mol/kg.h, and the energy consumption was 1.21 kWh/Nm³ O₂. In contrast, the 13X adsorbent exhibited lower performance with purities of 92.8% for oxygen and 92.4% for nitrogen, and recovery rates of 91% for oxygen and 93.4% for nitrogen. The oxygen productivity with this adsorbent was 0.381 mol/kg.h, and the energy consumption was 1.78 kWh/Nm³ O₂.