Comparative energy consumption in batch and continuous distillation

Abstract Distillation is the most important separation method in most chemical processes. For some fine chemical or pharmaceutical plants, both continuous or batch operation may be suitable. The decision as to whether a plant should be operated in continuous or in batch mode is in many cases the product of historic reasons rather than which mode is most economical for the given separation task. While it is generally noted that batch distillation columns have a higher energy consumption than equivalent continuous columns, no real comparison has been found in the literature. The purpose of this paper is therefore to compare the energy requirements of continuous and batch distillation for mixtures typical of the fine chemical industry. It is found that the energy consumption of batch operation is indeed higher than for continuous operation in all the cases investigated. However, when the total production costs are taken into account, batch operation is found to be favourable in some cases.