Hot Model Dividing Wall Distillation Column:Simulation And Implementation In A Pilot Plant

Distillation has the characteristics of high capacity and continuous operation,which was extensively used in separating multi-component mixture.However,high energy consumption and capital cost make the practitioners strive to find effective solution to further promote its energy efficiency.Hot model dividing wall column has shown to be energy efficient compared to conventional column sequence for multi components separation.Simulation of hot model dividing wall column was executed by Aspen Plus software,experiment of dividing wall column was implemented by the self-designed and guide-constructed pilot plant.A separation of alcohol ternary mixture of ethanol,1-propanol and n-butanol was researched,a set of comprehensive methods was proposed for the design and optimization of hot model dividing wall column.A complete short-cut design method of three column based on Fenske-Underwood-Gilliland-Kirkbride equations for DWC was used to get initial values of design parameters,besides,the simulation model of the rigorous calculation of the separation was established.This paper used Aspen Plus software to simulate the separate process of the sequences of conventional distillation and dividing wall distillation column,and column parameters and operation conditions were ascertained by simulation and optimization.Box-Behnken design(BBD)under response surface methodology(RSM)was used for the DWC optimizations,and to get better column parameters and operation conditions of dividing wall column.It provides a basis for the subsequent construction and control analysis of the pilot plant,by examining the influence of the heat transfer through a partition on the distillation process.Compared with the sequences of conventional distillation,thermodynamic and economic analysis was performed for the hot mold dividing wall column.Hot mold dividing wall column can generate capital cost increasing of 5.33%because more complexity of the DWC equipment was required.Besides,with their greater thermodynamic efficiency,hot mold dividing wall column can also reduce operating costs by around 33.35%,the total annual comprehensive was reduced by 25.85%.The separation of alcohol ternary mixture of ethanol,1-propanol and n-butanol was researched by the self-designed and guide-constructed pilot plant,including process flow,main equipment,instrument selection and operation rules.The results indicated that the composition of products,composition and temperature profile along the column were identical with the data of simulation results and the average relative deviation within the permissible values.On the basis of steady-state operation,constant disturbance of ±10%of feed flowrate and composition fluctuations in discharge was added,and the dynamic response performances of the hot mold dividing wall column sequence were investigated and three kinds of control structures were proposed.The results show that,after introducing the feed disturbances,the basic control structure(CS1)showed slower fluctuates and larger product deviation.The proposed Q_R/F and temperature cascade control structure(CS2)can effectively reduce product purity fluctuations and reduce the cycle of restoring balance;the improved control structure(CS3)can hold the products at high purities with small deviations and short settle time.