Shortcut method for multiple task batch distillations

A methodology is presented for the preliminary design of separation network s of batch distillation. Analytical partition functions are derived based o n the assumption that the distribution of components in an actual batch dis tillation can be approximated by the distribution of a batch column at tota l reflux. This permits computation of mass balances of multiple separation networks (allowing recycle of intermediate cuts) by solving a linear system of equations. Once the composition of the feeds to each separation task is known, the reflux ratios; required to perform the tasks can be computed by using a previously developed method that relates the minimum to the actual reflux ratios and number of stages. The validity of the assumption is test ed against simulation and the methodology compared with previously reported short-cut approaches. Since no new simplifications are introduced to the m odel, the reduction in computation effort is achieved with the same overall accuracy.