Generalised optimisation framework for the synthesis of thermally coupled distillation columns in the equation-oriented environment

In this paper, a novel superstructure optimisation method – The Generalised Optimisation Framework, is presented for the synthesis of a thermally coupled distillation system in the equation-oriented environment. The superstructure derived from a previous work considers all the sequencing alternatives from conventional sequences to fully thermally coupled distillation sequences. In our optimisation framework, a novel mathematical model is formulated to address the common failure of simulations when zero flowrate of streams enters units by using the “IF structure” syntax in Aspen Custom Modeller (ACM). The side rectifier configuration with the lowest total annualised cost (TAC) of 478,667 $ y(1 from a ternary complex distillation column superstructure is determined in conjunction with our previously proposed feasible path-based branch and bound method as the solution algorithm.