Dynamic Simulation Of Radial Flow Adsorber For Oxygen Production By Vacuum Pressure Swing Adsorption

With the increasing demand for oxygen and the expanding scale of industrial oxygen production,radial flow adsorber has been widely used for its lower energy consumption,less area occupation and easy expansion of production scale.In this paper,the numerical simulation of radial flow adsorber used in vacuum pressure swing adsorption(VPSA)for oxygen generation was carried out.The dynamic flow characteristics of radial flow adsorber were analyzed.The effects of process parameters and structure parameters on the flow field distribution and the performance of radial flow adsorber were discussed.VPSA is a complicated dynamic process,where mass transfer,heat transfer and momentum transfer all exist at the same time in the adsorber.It is difficult to measure parameters in adsorber through experiments.Therefore porous media model of FLUENT was coupled with adsorption process by User-Defined Functions.The mathematical model of radial flow adsorber for oxygen production by VPSA was established.The process of oxygen production by VPSA was simulated using the mathematical model.The results of dynamic simulation show that excessive volume of central channel will cause bad results of purge process,which has detrimental influence on the next oxygen production cycle.Excessive volume of the outer channel will retain more desorbed nitrogen,resulting in the decrease of adsorbent utilization rate as well as oxygen production efficiency.The study of operation parameters and structure parameters shows that the concentration and recovery of oxygen increases when smaller particles are used,which also improve the flow distribution.The increase of the cross-sectional area ratio of central channel and outer channel is beneficial to flow distribution.The radial non-uniformity of velocity reduces with the decrease of the opening ratio of distributor,and the influence of central distributor's opening ratio is more significant than that of the annular distributor on that phenomenon.With the increase of adsorption time,the oxygen concentration first increases and then decreases.Prolonging the purge time will further reduce the adsorption capacity of nitrogen,but has no obvious effect on the top of adsorber.Increasing purge ratio improves the results of the purge process and the oxygen concentration in next cycle,but reduces the recovery of oxygen.