Study On Operation Mode Of Constant Total Reflux Batch Distillation

A novel operation mode of constant total reflux batch distillation withmulti-vessel was proposed in this article, according to the advantages (such as highseparation efficiency and simple control method) of total reflux batch distillation. Themain characters of the new operation mode are:(1) The batch distillation column isalways operated under total reflux and without non-reflux or partial reflux period, sothe column makes full use of its separation capability;(2) The middle vessels aredistributed evenly along the column. Once the top concentration reaches the specifiedvalue, the vessels are moved upwards;(3) After each vessels exchange operation, thelast vessel is separated from the distillation system. There is no vessel connected tothe distillation column when the operation is terminated. The study on the newoperation mode was performed theoretically and experimentally in this article.The relative mathematic model was setup for the constant total reflux batchdistillation with multi-vessel, and the process simulation was carried out by Matlabprogramming.The influence factors of the new operation mode were discussed bysimulation, including tank parameters and feeding conditions. What’s more, thecomparison between the novel operation mode and the conventional constant refluxratio mode was conducted by simulation. The results show that the new operationmode has great advantages in separation efficiency and time saving, which is58.29%at most. And the advantages are more obvious when the separation of mixtures ismore difficult or the purity of product must be higher.The experiments of the constant total reflux batch distillation were carried outwith binary systems of methanol-ethanol, isopropanol-n-propanol and ethanol-n-propanol，in which the effect of feed concentration and the relative volatility wereinvestigated. Compared with the constant reflux ratio mode, the new operation modecan save time18.35%to32.70%. Also, the advantages of the new operation mode aremore obvious when the feed concentration is lower or the relative volatility is smaller.The experimental results are consistent with the simulation results, which verified theformer mathematical model is reliable.