The purification of dilute CO2/air solutions with an annular bed adsorber:numerical and experimental investigations

The annular packed bed adsorber is a promising development, because it offe rs a greatly reduced resistance to flow. Experimental and modelling work on the bed dynamics are described herein. A one-dimensional model of adsorption has been formulated. Thereafter, test s with different numbers of collocation points agree to the fourth signific ant figure. Similarly, our predictions can agree very well with Rosen's pre dictions for planar systems. (For these comparisons, gas residence times we re identical, and axial dispersions were ignored). The characteristics of zeolite 4A - pore diffusivities and Volmer isotherms - have been measured gravimetrically. They have been fed to a one-dimensio nal, dynamic, numerical model of the bed. Predictions were compared against recorded histories of concentration versus time at three sample points wit hin the bed. For outward flow, the agreement between prediction and measure ment is respectable at the bed outlet. For inward flow, experimental result s provide evidence of flow maldistribution. (This is supported by previousl y reported work). Thus, any comparison with a one-dimensional model is inap propriate. The influences of co-adsorption, heat of adsorption and maldistribution are worthy of future investigation. (C) 1999 Published by Elsevier Science B.V . All rights reserved.