Feed distribution in distillation: Assessing benefits and limits with column profile maps and rigorous process simulation

Abstract

This contribution describes the column profile map (CPM) methodology for designing distributed feed distillation columns. For non-sharp product distributions, a case study shows that energy savings of approximately 35% can be obtained if the feed stage(s) are designed optimally. Feed distribution allows capital cost savings, expands operating leaves, and can obtain greater separation feasibility. However, this column only has benefits in ternary and higer-order systems and when product distributions are non-sharp. To validate these counter-intuitive claims, a real Benzene, p-Xylene, Toluene system is modeled using CPMs, and the resulting design parameters are transported to Aspen Plus®. Using a sum of squared errors objective function to quantify savings, a cost saving trend very similar to the one predicted by the CPM method is obtained. This article therefore describes a complete design methodology for distributed feed systems and provides convincing evidence of benefits of such a system. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1668–1683, 2013