Stacked Side-Stream distillation sequences

Abstract

Distillation consumes a great deal of energy worldwide and research on methods to reduce this consumption is ongoing. One strategy is column stacking (CS), in which the operating pressures of the two columns are adjusted so that the condenser of one column can power the reboiler of the other column. In this work, forward and backward CS is applied to fifteen sidestream sequences. The results show that without stacking, the best side-stream sequence costs 80.3% of the conventional direct sequence, but when stacking is considered, the best stacked side-stream sequence costs only 69.3% of the conventional direct sequence, a further improvement of 11 percentage points or 56% additional savings. Furthermore, when side-stream sequences are ranked by cost, the order of sequences is substantially different when CS is considered. The results demonstrate that stacking should be considered in conjunction with side-streams for intensification of distillation sequences.