Design And Optimization Of Divided Wall Distillation Column For The Separation Process Of Cyclopentane

At present,the process of domestic refining and chemical integration industry is accelerating,ethylene production capacity is rising year after year,and the number of C5by-product separation units and products are also increasing.It is predicted that the cracking C5 production capacity will increase by 14.3%in 2021.Therefore,improving the utilization rate of C5 resources and developing new energy-saving processes will become the key to enhance the competitiveness of refineries.The general distillation technology is widely used in the current pentane separation projects to obtain the corresponding products.The process is complicated and the energy consumption of separation device is high.How to reasonably transform the existing device and optimize the production route is very important.In this paper,combined with the original separation project of cyclopentane,the design idea of divided wall distillation column process is proposed.The separation process of cyclopentane is divided into pretreatment unit and cyclopentane purification unit.The conventional four-column distillation process and divided wall distillation column process are simulated by ASPEN PLUS software.The sensitivity analysis is used to optimize several design variables of the divided wall distillation column.On this basis,Response Surface Methodology is used to optimize each variable.According to the fitted response function,the optimal process parameters of the divided wall distillation column are obtained.DMF（N,N-dimethylformamide）is selected as the extractant of cyclopentane/2,2-dimethylbutane system based on the influence of different solvents on the relative volatility of azeotrope system and the price factors.Cyclopentane purification unit mainly obtains cyclopentane products through extractive distillation process.The extractive distillation technology is combined with the divided wall distillation column to establish the model of extractive distillation divided wall column,and the process parameters are optimized by Response Surface Methodology.Compared with the two processes,the divided wall distillation column process has significant advantages:firstly,the separation process is simplified,and the original four-column process is improved to a double-column process;secondly,the overall investment cost and CO₂emissions are reduced by 15.2 and 22.2 percentage points respectively,which improves the economic and environmental benefits.According to the results of temperature,composition and flow rate distribution of the two processes,on the one hand,the divided wall distillation column process overcomes the disadvantage of large temperature difference between column walls of the traditional separation process,and improves the energy utilization;on the other hand,it reduces the backmixing effect and improves the distillation efficiency.According to the results of exergy analysis,the thermodynamic efficiency of the divided wall distillation column process is 5%higher than that of the original separation process.The divided wall distillation column process designed in this paper is based on the cyclopentane separation project of refinery,which has the practical transformation conditions.