Study On Energy Saving Distillation Process For Synthesis Of N-butyl Acetate And Isopropyl Acetate

In this paper,focusing primarily on the issues of low purity and high energy consumption in n-Butyl acetate production and isopropyl acetate production,pressure swing reactive distillation（RD-PS）,reactive distillation and pressure swing thermal coupling（RD-PSTC）,heat pump reactive distillation（RD-HP）and dividing-wall column reactive distillation（RD-DWC）were proposed on the basis of conventional reactive distillation（CRD）.Chemical simulation software ASPEN PLUS（version 10）was used to study steady-state simulation.In this study,these special energy saving processes were compared with conventional reactive distillation（CRD）in terms of energy saving,economy and environmental performance.Furthermore,taking TAC（Total Annual Cost）as objective function,a sequential iterative design method was proposed for these processes,and the optimal parameters of column operation were obtained.Finally,an ideal process design can be obtained.The thermodynamic data of acetic acid/n-butanol/n-butyl acetate/water system were calculated by using UNIQUAC physical property equation.When NT1（the total stages of the C1）was 15,NT2（the total stages of the C2）was 6,NFC2（The feed stages of the acetic acid）was2,NFC4（The feed stages of the n-Butanol）was 3,and NFB（The feed stages of the B1）was 2,the TAC of conventional reactive distillation process was the lowest.When the molar ratio of n-butanol to acetic acid was 1.05:1,the purity of n-butyl acetate reached 99.9 mol%.When the compression ratio of the compressor was set as 5 and the pressure of the low-pressure distillation column was set as 20 k Pa,the heat transfer temperature difference between the top and bottom of the distillation column can be satisfied.The simulation results of synthesis of n-butyl acetate by catalytic distillation results showd that compared with the RD-PS process,the RD-PSTC process can save 19.86%TAC,73.97%CO₂emission and 28.84%total energy consumption.Therefore,the RD-PSTC process was an economical and feasible process for the synthesis of n-butyl acetate.The thermodynamic data of acetic acid/isopropyl alcohol/isopropyl acetate/water system were calculated by using the NRTL-HOC physical property equation.When NC1（the total stages of the C1）was 24,NC2（the total stages of the C2）was 22,and Nrec（the number of reactive stages）was 8,the reboiler heat duty was lower,and the TAC of conventional reactive distillation process was the lowest.When the compression ratio was set to 3.95,the latent heat required to heat the bottom stream of C1was satisfied,ensuring the necessary temperature difference in heat transfer.The simulation results of synthesis of isopropyl acetate by catalytic distillation showed that compared with conventional reactive distillation（CRD）process,heat pump reactive distillation（RD-HP）process can save 13.46%TAC,13.25%CO₂ emission and 13.25%total energy consumption.The RD-DWC process can save 21.31%TAC,20.17%CO₂ emission and 20.17%total energy consumption.In general,the RD-DWC process had the optimal environmental,TEC（Total Energy Consumption）and TAC performance.