Vacuum Swing Adsorption Process for the Separation of Ethylene/Ethane with AgNO3/Clay Adsorbent

The performance of the 4-bed and 3-bed VSA process using AgNO3/clay adsorbent for the ethyleneseparation from C2 fractionator feed (83.56% C2H4, 16.4% C 2H6) was investigated experimentally and theoretically.With the 4-bed VSA proces, extremely high recovery of ethylene, over 99%, was obtained at ethylene purity of 9.8%.The recovery of the 3-bed proces was lower about by 1% than that of the 4-bed VSA process. But, the productivityof the 3-bed VSA was higher about by 33% than that of the 4-bed VSA process. The productivity of the 3-bed VSAproces was 3.7 mol/kg/hr at the ethylene purity of 99.8%. Efects of the rinse flow rate in the 3-bed VSA proces wereinvestigated by both experiment and simulation. The purity of ethylene was not significantly improved by the increaseof the rinse flow rate after it reached 99.8%. At the rinse flow rate where the purity was 99.9%, the recovery became70%. It might be attributed to the slow difusion of ethane. Acording to the simulation, ethylene purity of over 99.9%could be obtained with recovery of over 90% only when the mass transfer rate of ethane is lower than 1.010-4 s-1 orhigher than 0.2 s-1. The productivity of the process could be improved by increasing the feed flow rate at the expenseof the recovery. Acording to the simulation, at the feed flow rate of 5,0 ml/min, the productivity of 5.2 mol/kg/hrwas obtained at the ethylene purity of 99.5%. KCI Citation Count: 15