Solvent vapor recovery by pressure swing adsorption. II. Experimental periodic performance of the butane-activated carbon system

An experimental investigation was carried out for the separation and recovery of butane vapor (10 to 40 vol%) from nitrogen using Westvaco BAX activated carbon and a unique pressure swing adsorption (PSA)-solvent vapor recovery (SVR) system. The effects of six important process and operating parameters on the periodic process performance were obtained, i.e., the purge-to-feed ratio, purge pressure, volumetric feed flow rate, feed concentration, cycle time, and pressurization/blowdown step time, Overall, the experimental results were consistent with theoretical results in the literature for the effects of most of these parameters; however, some opposite and unique trends were observed. The experimental results verified that the concentration wave front may be contained within the bed even when the purge-to-feed ratio is less than unity, and that the process performance may be very sensitive to minor changes in the purge pressure. Moderate temperature swings (18 to 54 degrees C) were exhibited in all cases, and they decreased with increasing bed coverage, especially when breakthrough occurred. Also, when the bed coverage increased, the mass transfer zone also increased. Finally, these experimental results provided significant insight into designing more efficient PSA-SVR processes and developing new PSA-SVR cycle configurations for improved solvent vapor enrichment.