Synthesis and Integrated Design of a Compact Azeotropic Process for EtAc–MeOH–Water Separation

This study presents the synthesis and design of a two-column compact distillation (CD) process for separating a dilute ethyl acetate (EtAc)–methanol (MeOH)–water mixture, which has two minimum boiling azeotropes, into its constituent (nearly) pure components. The synthesized flowsheet leverages the pressure sensitivity of the azeotropes as well as the liquid–liquid phase split for efficient separation. To improve the energy efficiency, the basic flowsheet, consisting of a decanter, a high-pressure simple column, and a low-pressure divided-wall column, is heat-integrated (HI) using external heat exchangers to obtain the HI-CD process. The most energy-efficient hybrid-CD process is obtained by incorporating vapor recompression-driven reboil in the two columns along with external process-to-process heat exchange. A quantitative comparison with the recently reported best design, namely, the hybrid heterogeneous triple-column distillation (HTCD) process, reveals substantial economic and sustainability advantages of the proposed hybrid-CD process design. Specifically, the total annualized cost of the hybrid-CD process is lower by 15.4% compared with the hybrid-HTCD process. Energy consumption and CO₂ emission are also significantly lower by 34.3 and 31.4%, respectively.