The Study Of Separation Of Acetone-Heptane Azeotrope By Extractive Distillation

In the process of chemical production,a variety of azeotropic compounds are produced,which may be not appropriate to separate them using general distillation methods,such as acetone-heptane and methanol-carbon tetrachloride.Extractive distillation is one common method in distillation process,and it is suitable for the separation of azeotrope and almost boiling point mixture.This method is to add a third component to separated mixture,which could increase volatility of the mixing components,and then achieving the aim of separating the mixture.In this paper,a mixture of acetone and heptane was separated by extractive distillation using benzene as extracting agent.Firstly,direct and indirect separation sequences were carried out to simulate and optimize steady state.In the separation process of direct sequence,the relative parameters after optimization:0.83atm of pressure of extractive distillation,70 of stages,the 63th and 37th of feed-stage position of mixture and solvent respectively,500C of solvent,30kmol/h of feed flow of solvent.0.40atm of pressure of solvent regeneration distillation,65 of stages,the 55th of feed location.The optimal value of Total Annual Cost(TAC)is 1.34×106$/year.In the separation process of indirect sequence,the relative parameters after optimization:0.55atm of pressure of extractive distillation,50 of stages,the 42th and 7th of feed location of mixture and solvent respectively,50? of solvent,9kmol/h of feed flow of solvent.0.80atm of pressure of solvent regeneration distillation,55 of stages,the 49th of feed-stage position.The optimal value of Total Annual Cost(TA C)is 1.195×106$/year.Considering economic aspect,it can be seen that indirect separation sequence could be more suitable for steady state.Furthermore,Aspen Dynamic was carried out to simulate these two sequences,respectively.According to the simulation results,when flow rate and composition(acetone)disturb the control structure,indirect separation sequence has a good anti-interference performance from response curves of products purity and temperature of sensitive stage.In the indirect separation sequence,the second control structure of QR1/F is better.Through steady state and dynamic simulation results,it can be seen that indirect separation sequence,which was carried out to separate the mixture of acetone and heptane,is more economical.The relative optimization in the process also provides a useful reference for further study of the separation of acetone and heptane mixtures.