Synthesis of heat-integrated distillation sequence systems

Energy-efficient distillation systems can be achieved through the mathematical optimisation of distillation sequencing in which heat integration is simultaneously considered. Genetic algorithms have been employed to optimise the most appropriate sequences based on both simple and complex columns for a given separation requirement, with rigorous economic trade-offs between energy and capital costs used in the determination of distillation sequence. Thermodynamic and economic performance of distillation columns has been simulated and measured with short-cut models, while a conceptual decomposition method has been applied for evaluating complex columns. An incidence matrix has been proposed to identify the optimal heat recovery between available heat sources and sinks existing in the distillation sequence. Two case studies have been presented to demonstrate the importance of considering heat integration simultaneously in the optimisation of distillation sequencing, and 8-17% of overall cost savings have been achieved, compared to the conventional synthesis method. © 2012 Taiwan Institute of Chemical Engineers.