Study on energy saving of heat integrated distillation process for methyl acetate–methanol–tetrahydrofuran–water

Based on the characteristics of binary azeotropic composition in the mixture of methyl acetate–methanol–tetrahydrofuran–water sensitive to pressure, pressure swing distillation (PSD) and double-solvent extraction distillation (DSED) were proposed to study the separation of the quaternary system. Numerical simulations were performed by ASPEN PLUS software (version 10.0) environment under the WILSON thermodynamic model. The economy of PSD and DSED process was performed, and the heat integration of two distillation processes was compared based on total annual cost (TAC). Research results of PSD indicated that compared with conventional PSD (CPSD), heat-integrated PSD (HIPSD) can save energy consumption and TAC by 33.87% and 30.70%, respectively, and moreover increase thermodynamic efficiency by 1.77%, so it had obvious energy-saving effect and economic advantage. Simulation results of DSED showed that water (H2O) and ethylene glycol (EG) were most suitable extractants for the system, and the suitable solvent ratios for H2O and EG were 0.28 and 0.38, respectively. Compared with conventional double-solvent ED (CDSED), heat-integrated double-solvent ED (HIDSED) can save energy consumption and TAC by 43.29% and 28.12%, respectively, and moreover increase thermodynamic efficiency by 3.25%, so it was superior to CDSED. The results indicated that the energy consumption and TAC of HIDSED are respectively 63.56% and 44.01% less than the HIPSD process, and the thermodynamic efficiency of the former is 3.9% larger than the latter, so the HIDSED process shows better economic and energy-saving effect.