EXPERIMENTAL-STUDY ON A 4-BED PSA AIR SEPARATION PROCESS

A 200-s PSA cycle involving both pressure equalization and product bac kfill steps has been experimentally studied on a four-bed system, wher e LINDE 5A zeolites were used as the adsorbent to separate oxygen from air. This cycle is operated under a pressure ratio of 4.3. During the experiment, the pressure history and flow rates, as well as the conce ntration of the product stream have been continuously monitored. This is the first time detailed experimental data on a four-bed system are presented. Under favorable conditions, this system produces better tha n 90% oxygen at a recovery of 17%. For the low-pressure ratio, such a recovery could not have been achieved without the pressure equalizatio n step and the reduced purge operation. Recovery and throughput, howev er, are not as high as one would expect from a linear local equilibriu m model. The self-broadening effect of the purge wave has been identif ied as the major cause of underperformance.