Equilibrium theory for pressure swing adsorption. 5. Separation and purification in multicomponent adsorption

We analyze the periodic behavior of an adsorption bed that is alternatively fed with a dilute ternary mixture of adsorbable components in an inert car rier gas and purged countercurrently and incompletely with pure inert gas. We rely on local equilibrium theory to determine the asymptotic wave charac ter of the process. We consider one purification and two separation problem s and illustrate (i) how the duration of the feed step can be determined on the basis of the duration of the purge step and (ii) where intermediate sh ocks are located at the end of the feed step for the periodic state. We sho w how the approach used for a three-component system can be generalized to a system with n adsorbable components. Partial analytical contributions to the solution of one of the separation problems are provided to illustrate h ow the method of characteristics can, even for such complex systems, provid e insight into the types of wave interactions taking place in the bed.