Optimal synthesis of para-xylene separation processes based on crystallization technology

This paper addresses the synthesis and optimization of crystallization processes for p-xylene recovery, A novel superstructure for the overall crystallization process and a mixed-integer nonlinear programming (MINLP) model are proposed. The distinct feature of this superstructure is the capability of generate optimum flowsheets for a wide range of specifications of p-xylene composition in the feed stream of the process. To cope with the complexity of the MINLP model a two-level decomposition approach consisting of the solution of an aggregated model and a detailed model is proposed. The results obtained show a good performance of the decomposition strategy and a modest improvement in the total annual profit.