Energy and Economic Evaluation of Wall Placement for\nDivided Wall Distillation Columns

Divided\nwall columns (DWC) implemented as a form of process intensification\nfor conventional distillation configurations for azeotropic systems\nnormally use an entrainer for breaking the azeotrope. By contrast,\nthis study uses water/isopropanol/acetone as a model chemical system\nwith the goal of having a water/isopropanol azeotropic composition\nas one of the products. The direct conventional and indirect conventional\nsequences and middle wall DWC, top wall DWC, and bottom wall DWC were\ninvestigated by Aspen Plus simulations, which allowed for product\ncomposition, economic, and energy usage comparison between the distillation\nconfigurations. The effect of wall placement on economics and energy\nusage was evaluated for the model chemical system. All of the distillation\nconfigurations produced the same product compositions with the middle\nwall DWC having the lowest associated economic and energy cost. The\nmiddle wall DWC had at least 8% fixed capital investment and 14% energy\nsavings compared to the conventional sequences. The location of the\ndividing wall affected the economic and energy costs, with the middle\nwall DWC still having the lowest associated costs.