Synchronous and asynchronous SMB processes for gas separation

Abstract

AbstractThe simulated‐moving bed (SMB) is now a well established adsorption process for obtaining high‐purity products at a similarly high‐recovery. In principle the SMB process can be applied to gases, and has been, but application has been limited. Here, we re‐examine the SMB process for separation of gaseous components in the light of recent developments in novel cyclic operating schemes and advanced optimization tools. A novel single‐column experimental setup is employed to demonstrate the feasibility of the process, explore the effect of its major operating parameters, and illustrate the performance enhancements that are obtained by using an advanced cyclic operation scheme, such as the asynchronous shifting of the inlet/outlet ports. The experimental feasibility and effectiveness of gas‐phase SMB are assessed by running and comparing optimized configurations for the separation of CH4/CO2 over activated carbon using nitrogen as carrier gas. For this separation, the asynchronous configuration always outperforms the classical SMB scheme, both in productivity and eluent consumption, except at very low‐feed throughput where both schemes are coincident. At higher‐feed flow rates, the asynchronous scheme quickly diverges from a four‐zone, closed‐loop configuration towards a three‐zone, open‐loop process with a 50.6% increase in feed throughput, and 10% reduction on eluent gas consumption. © 2007 American Institute of Chemical Engineers AIChE J, 2007