Through this study, we have completed the simulation of ethanol dehydration process using an azeotropic distillation process with benzene to obtain a nearly pure anhydrous ethanol product from aqueous ethanol mixture. NRTL liquid activity coefficient model and PRO/II with PROVISION 7.01, a commercial process simulator were used to simulate an azeotropic distillation process. We determined the total reboiler heat duties as an objective function and a concentration of ethanol at concentrator top as a manipulated variable. As a result, 76 mole percent of ethanol at concentrator top gave an optimum value which minimized the total reboiler heat duties of three distillation columns.