Energy-saving design of azeotropic distillation for the separation of methanol–methyl methacrylate azeotrope from industrial effluent

Abstract

For the purpose of separating the binary methanol–methyl methacrylate (MMA) azeotrope in light boiling residues and preventing MMA polymerization from acetone cyanohydrin process, low pressure heterogeneous azeotropic distillation (HAD) with process intensification was adopted. The binary interaction parameters of the azeotrope were obtained by correlating and regressing the experimental data of isobaric vapor–liquid equilibrium at low pressures (75, 50 and 26 kPa for methanol-MMA and 26 kPa for cyclohexane-MMA). The residue curve map at 26 kPa was plotted under the UNIQUAC model, and the optimal parameters of its conventional process were achieved through sequential iterative optimization procedure. The purity of MMA and methanol was 99.99 wt% and 99.90 wt%, respectively. Subsequently, in order to further reduce costs and energy consumption, dividing wall column (ADWC), heat pump distillation (HP-AD), and heat pump assisted azeotropic dividing wall column (HP-ADWC), three technical approaches were explored and compared. Total annual cost (TAC), total energy consumption (TEC), and CO2 emissions were used as evaluation indicators. Among them, ADWC reduced its annual capital investment by 14.48 % through special structural design. HP-AD effectively reduced TEC by 27.30 %. HP-ADWC combined the advantages of both, effectively reducing costs and saving energy (12.88 % in TAC). At present, the purity and energy saving of the product meet industrial expectations, providing valuable insights for enhanced methanol-MMA azeotrope recovery from industrial effluent.