(320e) Studies in Continuous Countercurrent Pressure-Difference-Driven Gas Adsorption Separations

Some years ago, we reported the use of of Simulated Moving Bed (SMB) and Rotary Valve technologies in gas adsorption separations. This was done in the context of Continuous Countercurrent Pressure Difference-Driven Adsorption Process (CCPDDAP), what appeared to us an obvious way of running a gas separation cycle. A non obvious result was that the CCPDDAP was not able to easily match or improve on the separation efficiency of a conventional PSA or VSA cycle.   A possible explanation was that adsorption equilibrium tends to be highly nonlinear and that it was not possible to obtain an efficient cycle with a single gas/solid flow ratio to match the adsorption curve. In this paper we report on the results of breaking the unit in several stages, each of which has a different gas/solid flow ratio, to improve the separation performance. Comparison of units with up to three countercurrent contacting stages will be presented, as well as the result of the separation with a conventional PSA plant.