Separation of acetonitrile/methanol/benzene ternary azeotrope via triple column pressure-swing distillation

• TCPSD for separating acetonitrile/methanol/benzene was investigated.
• Feasibility of TCPSD to separate ternary system was analyzed by triangular diagrams.
• Process parameters were optimized using Aspen Plus and Visual Basic.
• The best sequence of TCPSD was obtained based on economics.

Acetonitrile/methanol/benzene mixture forms more than one different azeotropes and its triangular diagram presents several distillation boundaries at atmospheric pressure. A process named as triple column pressure-swing distillation (TCPSD) was proposed to separate this complex ternary system. The feasibility of the process was confirmed using residue curve maps and rigorous steady-state simulations were implemented on Aspen Plus. On basis of minimum total annual cost, several operating parameters were optimized by pressure-swing optimization software using the sequential iterative optimization procedure and the economics of TCPSD were compared with four different separation configurations. The results demonstrated that the A-M-B separation configuration was the most optimal column sequence in global optimization to separate acetonitrile/methanol/benzene azeotropic mixture using TCPSD. TCPSD may arouse the interest of researchers in various fields and can assist engineers to select the optimal separating process.