SOLVENT VAPOR RECOVERY BY PRESSURE SWING ADSORPTION - I - EXPERIMENTAL TRANSIENT AND PERIODIC DYNAMICS OF THE BUTANE-ACTIVATED CARBON SYSTEM

An experimental investigation was carried out for the separation and r ecovery of butane vapor (10 to 40 vol%) from nitrogen using Westvaco B AX activated carbon in a twin-bed pressure swing adsorption (PSA) syst em utilizing a 4-step Skarstrom-type cycle. Twenty-four runs, covering a broad range of process and initial column conditions, were performe d to investigate the transient and periodic process dynamics. In all c ases the approach to the periodic state was very slow, taking up to 16 0 cycles depending on the initial condition of the beds; and peak bed temperatures of up to 105 degrees C were observed depending on both th e initial condition of the beds and the process conditions. Also, the periodic state of each run was unique when approaching a new periodic state from less contaminated beds. The uniqueness of the periodic stat es, together with the exceedingly high peak temperatures, inferred muc h about the practice of preconditioning beds to avoid high temperature excursions. The periodic enriched butane vapor concentration historie s also gave considerable insight into new cycle designs for improved s olvent vapor enrichment.