Multicomponent Batch Distillations Campaign: Control Variables and Optimal Recycling Policy

To optimize a process, one first must determine the variables acting on the process. This publication will inventory the control variables in various campaigns of multicomponent batch distillations with and without the recycling of offcuts. The problems that are involved in optimizing these multicomponent batch distillations campaigns then will be stated. The chosen optimization variables are the feed time at the reboiler, the recovery time of a main cut, the proportion of a recycled cut at a batch, and the reflux ratio. The results show that, overall, the optimum values of a batch distillations campaign of a given product are not transferable to another different campaign for the same product and the same composition. The optimal strategy corresponds to the recycling of the second offcut obtained at a batch to the following batch distillation when the added cut and the contents at the reboiler have similar compositions, with the first offcuts being put together for a separate batch distillation.