Synthesis And Design Of Dividing-Wall Distillation Column Processing An Intermediate-Component-Dominated And Wide-Boiling-Point Ternary Mixture

Vapor recompression heat pump assisted dividing-wall distillation column(VRHP-DWDC)is a distillation technology with broad application prospects.At present,the research on Vapor recompression heat pump(VRHP)is in the ascendant.Many researchers have revealed the significant economic benefits and substantial improvement of steady-state performance brought by the application of VRHP in different separation processes.However,The configuration of double columns and multiple separating sections for a dividing-wall distillation column makes the applications of vapor recompression heat pumps become a challenging task with great complexities and tediousness.In addition,VRHP-DWDC inevitably faces the problem of large temperature span when processing a wide-boiling-point ternary mixture.These unfavorable factors hinder the application and development of VRHP-DWDC.In the current work,through the thermodynamic analysis of the ideal ternary mixture separated by DWDC,we demonstrated the nonlinear relationship between the recovery rate of intermediate components at the top of the pre-fractionator and the excessive heat at the location of intermediate products,and analyzed the change trend of recovery rate during process intensification.Based on the steady-state characteristics,DWDC,two single-stage VRHP-DWDCs and the VRHP-DWDC optimum topological configuration facilitated by two heat pumps are given respectively.The two VRHPs of VRHP-DWDC optimum topological configuration release the heat of intermediate product location and overhead steam to common stripping section for process intensification respectively.After being preheated by the condensate of intermediate product steam,the overhead steam with lower temperature can overcome the obstacle of large temperature span between the overhead and common stripping section.Therefore,the heat of overhead steam can also be used to assist the separation process in DWDC,so as to further reduce the irreversibility of distillation operation.Two ternary mixtures are studied to compare the economic performance of the above three configurations.Taking total annual cost as the economic objective function,the detailed operation and structural variables are obtained through the optimization procedure.According to the simulation results,the total annual cost of the optimum configuration is reduced by 31.72% and8.01% respectively compared with the conventional configuration.This confirms the optimality of the proposed VRHP-DWDC.For the DWDC with upper and lower partitions,the optimum topological configuration can still be deduced in the above strategy.These results show the effectiveness and applicability of the VRHP-DWDC synthesis and design strategy proposed in this paper.