Process Intensification: Revive Your Columns with Cyclic Distillation

Process intensification in distillation systems has received much attention, with the aim of increasing both energy efficiency and separation efficiency. Various techniques, such as internal heat-integrated distillation, membrane distillation, rotating packed bed, dividing-wall columns and reactive distillation have been studied and reported. However, those techniques employ the conventional continuous counter-current contact of vapor and liquid phases. This article gives an overview of an alternative operating mode — known as cyclic distillation — based on separate phase movement that leads to key advantages. It explains the working principle, design and control methods, the main benefits and limitations, and industrial applications. Cyclic distillation can be rather easily implemented in existing columns by simply changing the internals and the operating mode, thus bringing new life in old towers by significantly increasing the column throughput, reducing the energy requirements and offering a better separation performance.