The pressure swing adsorption (PSA) process for anhydrous alcohol (99.5wt%) production from a flow of ethanol feed vapor (92wt%) was studied by simulation. This work developed three kinds of PSA process, i.e., a two-bed four-step process (Skarstrom Vacuum), a two-bed six-step process (including purge step), and a two-bed eight-step process (including purge step and backfill step). The simulation showed that two-bed eight-step process achieved the best purity with 99.5wt% ethanol and a 96.2% recovery. Therefore, the study discussed performance difference of two-bed eight-step PSA process between general non-isotherm system and adiabatic system. The results showed that general non-isotherm system didn’t perform better than adiabatic system, but consumed more energy than adiabatic system.
The optimal operating condition was obtained by varying the operating variables, such as feed pressure, adsorber length, vacuum pressure and step time. An increase in the feed pressure, vacuum pressure, and production step time caused a decrease in the purity of ethanol. On the other hand, an increase in the adsorber length and purge time caused an increase in the purity of ethanol. An increase in the adsorber length, vacuum pressure, and purge time caused a decrease in the recovery of ethanol. However, an increase in the feed pressure and production step time caused an increase in the recovery of the ethanol. The suggested operating conditions are: feed pressure of 3.4014 atm (50 psia), feed temperature of 423.14 K, product pressure of 1 atm, vacuum of 0.1 atm in the desorption and a cycle time of 600 s.