Steady State Simulation of an Azeotropic Distillation System Using Aspen Plus

Abstract

Ethanol-water forms homogeneous minimum boiling azeotrope and it has most common occurrence in many industrial processes. There are various techniques exist to separate azeotropic compositions. In this work we studied the basic features of azeotropic distillation using Aspen plus simulation. Since entrainers are indispensable in separating constant boiling mixtures, in this work, performances of three different entrainers were studied viz. benzene, n-pentane and cyclohexane. The effect of various process variables viz. reflux-ratio and distillate rate on the purity of the final products was studied in detail. RadFrac simulator was used to study the distillation process and NRTL method was used as the base thermodynamic method. It has been found out after simulation that cyclohexane performed best where maximum purity of ethanol (99.91%) was obtained closely followed by n-pentane (99.84%) and benzene (99.77%) as entrainers. The optimum number of stages were 25 (for n-pentane), 45 each for benzene and cyclohexane respectively.