This work presents an alternative structure for multivessel batch distillation and focuses on the determination of an optimal programming for it. The system is composed by a set of heated or cooled vessels connected by total reflux distillation cascades. This structure is able for separating multicomponent mixtures achieving simultaneously desirable specifications for all components, without loss of material and avoiding complex control strategies. An optimization problem is formulated in order to maximize a profit function assigned to a separation task. Transformed decision variables together with a smooth price function, are used to pose the problem according to an unconstrained form. The decision variables are the vapor molar flow rate and the operating time of each column. Batch separations of ideal quaternary mixtures are optimally programmed regarding purity specifications under fixed number of stages in each cascade and with an upper bound on the total rate of heat consumption.

In this work, several simulated annealing algorithms presented in the literature as solutions to different problems were compared in the scheduling of multiproduct serial batch plants. A systematic performance study of the original algorithm, based on the Boltzmann statistics, and a recently proposed algorithm, based on the Tsallis statistics, were analyzed for three different annealing schemes. It was observed that performance (defined in terms of the number of configurations) is more sensitive to the annealing scheme than to the statistics used. We also observed that the overall performance of the simulated annealing procedure is very dependent on the parameters of the algorithm and on the kind and size of the problems. For large problems, algorithms based on the Tsallis statistics converged to the global minimum more frequently than those based on the Boltzmann statistics, although they needed a larger number of configurations to obtain the results.