The Simulation Of The Fully Thermally Coupled Distillation Columns For Naphtha Extraction System

The naphtha product in a refinery aromatics extraction workshop is distribution of C3-C11,and the aromatics are mainly distributed in C6-C9.The naphtha should be subjected to preliminary separation to improve the separation efficiency of aromatics extraction,the fraction containing aromatic hydrocarbon was separate out and then the extraction was carryied out.This topic uses the Aspen plus process simulation software,select the DWC to simulate and calculate the naphtha system in the aromatics extraction plant to effectively obtain the aromatics-rich components of naphtha.This article focus on the following points for analysis and research:Analyzed the components and properties of naphtha in aromatics extraction workshop.According to the content distribution of aromatics in naphtha feedstock,the light naphtha,medium distillate,and heavy naphtha were determined;The shortcut design of the four-column model of the DWC is studied and the three representative components of n-pentane,cycloheptane and 2,2,4-TriMethylhexane are selected for the shortcut design calculation of DWC.The result of the shortcut design calculation for providing the basic data for the rigorous design of the DWC;The method of Aspen plus software was used to simulate the four-tower model of the partition wall.The preliminary study was carried out on the naphtha system of the aromatics extraction workshop;The DWC preliminary rigorous simulation is optimized,including the procedure variable of theoretical plate number and distribution ratio,and then the optimum parameters and operating conditions are obtained.The distribution of the composition of the partition wall column,the vapor and liquid flow rate,the temperature and the number of theoretical plates,the hydrodynamic data was investigated.The reason of the DWC energy saving is compared with the traditional distillation column.And the traditional distillation column separation technology of aromatics extraction naphtha was compared with the DWC.The energy consumption,CO2 emission calculation and thermodynamic efficiency of DWC distillation process was compared with the traditional distillation column.The heat-exchange equipment design and calculation of the DWC condenser and reboiler heat exchanger was carried out by Aspen EDR,and then the design parameters and structure dimensions of reboiler and condenser in two separate processes are obtained,while the investment cost and operation cost of two separation process was estimated.Compared with the distillation process of the traditional distillation column,the investment cost of the reboiler and condenser of the DWC is basically flat,but the operating cost has obvious advantages.