Minimum energy demand for nonideal multicomponent distillations in complex columns

The minimum energy demand of a specified separation is a key parameter in process design. However, a simple and fast short-cut method applicable to all types of splits and mixtures in both simple and complex columns is not yet available. In this paper a new general method for calculating the minimum energy demand for distillation columns is presented. It stems from a geometric analysis of the plate-to-plate profiles and uses all pinch points of both column sections. No a-priori choice of relevant solution branches of the pinch equations is required. The computational effort is low since no rigorous plate-to-plate calculations are necessary. The method can be applied to nonideal multicomponent mixtures of an arbitrary number of species and is not restricted to any type of split. Its extension to complex columns with sidecolumns or sidestreams is outlined.