Semi-batch distillation (SBD) differs from the batch distillation (BD) in that one part of the feed is continuously fed. The liquid volume in the reboiler has usually a minimum value because of different reasons. The application of semi-batch distillation might be advantageous in cases where the prescribed purity of the less (B) or the loss permitted of the more volatile (A) component cannot be reached because of the above constraint. In the first case study morpholine (B) must be produced from a dilute aqueous solution in high purity. In the second case study acetone (A) is produced from a mixture with low-water content. Different BD and SBD operational policies are studied by dynamic simulation with a professional flow-sheet simulator, and compared on the basis of the specific energy demand of production of the valuable component. The SBD policies differ from each other in the feeding location. The possibility of varying feed location is also studied.
