Energy Reduction through Heat Integrated In Multi-effect Distillation Columns

Heat integration of distillation columns with focus on multi-effect distillation, where the column pressures are adjusted such that the cooling (energy removal) in one column can be used as heating (energy input) in another column, is studied in this paper. The emphasis of the work is on the energy savings of such arrangements, looked at mainly in terms of capital and operating costs. Two cases have been simulated using rigorous simulation program (Hysys) to verity the results, a non-integrated base case and a multi-effect arrangements. Then two distillation columns in sequence have been studied to see if it was suitable for integration using a multi-effect arrangement in order to reduce costs and also the effect of changing pressure, reflux ratio, number of trays and other parameters are considered on design and costs. Based on theoretical considerations and economically evaluated rigorous case studies for ternary mixtures it is demonstrated that multi-effect distillation has a much lower overall energy requirement and total cost than a conventional distillation arrangement.