Co-process Intensification Philosophy And Synthesis And Design Of Reactive Double Dividing-wall Distillation Column

Reactive dividing-wall distillation column(R-DWDC)is a distillation technology with broad application prospects.For multi-component distillation,the reactive single dividing-wall distillation column(R-SDWDC)allows significant energy savings by avoiding the remixing effects.However,in the seperation of reacting mixtures with unfavorable reaction kinetics and unfavorable thermodynamics properties,the R-SDWDC cannot represent the most energy efficient process alternative.In the current work,through analyzing the structural defect of R-SDWDC and conventional reactive distillation system(CRDS),it is found that the great irreversibility in the separation operations involved in the CRDS and R-SDWDC represents the major reason that degrades the whole system performance,and according to the principle of process intensification,a novel co-process intensification philosophy is proposed for the synthesis and design of reactive dividing-wall distillation columns.It is readily noted that the pursuit of co-process intensification philosophy has been performed simultaneously in the two subsystems of the R-DWDC.While one kind of process intensification is achieved between the reaction operation and some associated separation operations involved and works mainly to suppress the unfavorable reaction kinetics,the other kind of process intensification is pursued between the remained separation operations involved and serves mainly to lower their operation irreversibility.On the basis,the philosophy leads to the establishment of plenty of reactive double dividing-wall distillation columns(R-DDWDC).In terms of two example systems involving,respectively,the separation of the ideal quaternary reversible reaction with a somewhat unfavorable ranking of relative volatilities(A+B(?)C+D withα_A>α_C>α_B>α_D)and the separation of transesterification of methyl acetate with n-propanol,it is appropriate to choose the minimization of total heat duties of reboilers as the objective function for process synthesis and design.The commonly used grid search method is adopted to tackle the optimization problem.According to the simulation results,the total heat duties of reboilers in the R-DDWDC is reduced by 26.15%,21.21%and 27.97%,17.19%,compared to the CRDS and R-SDWDC respectively.Therefore,the R-DDWDC is always found to yield much better performance than the CRDS and R-SDWDC,and such outcomes definitely corroborate the effectiveness and advantages of the proposed methodology for process development.Although the proposed philosophy is developed solely based on the separations of the reacting mixtures with somewhat unfavorable ranking of relative volatilities,it is of great implication to the separations of the other reacting mixtures with unfavorable reaction kinetics and unfavorable thermodynamics properties.