Design And Simulation Of Dual Reflux Pressure Swing Adsorption For Air Separation

Oxygen and nitrogen are two very important industrial gases,and their uses involve many fields such as chemical industry,national defense,and machinery.The demand is also in the forefront of global gas production.In this paper,pressure swing adsorption technology is used to separate the air and Li LSX molecular sieve is used as the adsorbent.Based on numerical simulation method,a two-bed dual reflux PSA air separation process is established in Aspen Adsorption software and then simulation and improvement are performed respectively.The effects of some operating parameters on purity and recovery rate of nitrogen and oxygen were investigated,including feed position,adsorption time,light component reflux flow rate and heavy component product flow rate.Based on the evaluation indicators of purity,recovery rate,processing capacity,adsorbent productivity and energy consumption,we compared the separation performance of dual reflux process and two improved processes.The results show that both dual reflux process and two improved processes can obtain about 95%oxygen in purity and the recovery rate are above 95%,the purity and recovery rate of nitrogen are about 98%and 99%respectively.The processing capacity of dual reflux process,improved processⅠand improved processⅡare 87.769,162.588 and 175.539L/（kg h）,the adsorbent productivity are 17.436,34.007 and 36.741 L_O2/（kg h）and the energy consumption are 1.897,0.682 and 0.763 k Wh/m³O₂.It can be seen that the processing capacity and adsorbent productivity of two improved processes are about twice that of dual reflux process,while the energy consumption are only about one third of dual reflux process.When comparing the two improved processes,it can be found that the energy consumption of processⅠis lower and the processing capacity and adsorbent productivity of processⅡare larger.In conclusion,the dual reflux PSA process can simultaneously obtain high-purity and high-recovery light and heavy component products.The two improved processes can effectively increase the processing capacity and adsorbent productivity and reduce energy consumption.This integration method provides ideas for the improvement of dual reflux process and industrialization research.