Abstract
In this paper, three quality or performance indices (Luyben's capacity factor, total annual costs, and annual profit) were applied for the design of a batch distillation column working at variable reflux. This work used the Fenske-Underwood-Gilliland short-cut method to solve a problem of four components (benzene, toluene, ethyl-benzene, and ortho-xylene) that needed to be separated and purified to a mole fraction of 0.97 or better. The performance of the system was evaluated using distillation columns with 10, 20, 30, 40 and 50 theoretical stages with a boil-up vapor flow set at 100 kmol/h. It was found that the annual profit was the best quality index, while the best case for variable reflux was the column with 50 stages. It was confirmed that the best case always required a reflux ratio close to the minimum.
Keywords
Batch distillation; Short-cut method; Variable reflux; Performance indices; Luyben´s capacity factor; Total annual cost; Annual profit
