Batch time (energy) requirements are provided for the separation of a zeotropic mixture in three batch column configurations. The separation tasks were performed in two different multivessel column arrangements (with and without vapor bypass) and a rectifier column. All columns are operated as closed systems. The elimination of the vapor bypass in the multivessel column improves the composition dynamics in the middle vessel significantly. The modified multivessel column (without the vapor bypass) requires 30% less time than the conventional one (with the vapor bypass). The effect of the feed composition and product specification on the time requirements is also studied. The multivessel arrangements perform always better than the rectifier column, which requires from 35 to 100% more time to perform a given separation. All results are based on dynamic simulations of the processes. (C) 2004 Elsevier Ltd. All rights reserved.