Abstract
Present tendency in rectification: energy economizing. Rectification columns are the greatest consumers of energy in many chemical plants. Decreasing their energy consumption has been a long term aim in process engineering. These considerations have culminated, for example, in the splitting of a separation between two columns operating at different pressures to make an energy match feasible, the application of heat pumps, of intermediate evaporators and condensers, and also the joint execution of different separations in one column with several feeds and side streams. These ideas were formerly often thwarted by high investment costs and (supposed) reduced flexibility; in recent years, however, the design of complex plants with extensive energy matching has become commonplace. A prerequisite is the feasibility of calculating sufficiently exactly the necessary separation units; moreover, there is also a need for efficient column intervals and heat exchangers which can operate with small pressure drops and modest temperature gradients. A general energy‐saving strategy also leads to process modifications in other separation techniques such as liquid‐liquid extraction.