∞/∞-Analysis of heterogeneous distillation processes

Abstract

A short-cut method for the conceptual design of processes consisting of distillation columns and decanters is presented. It extends the previous work on homogeneous distillation columns and processes (Ryll et al., 2012b) to heterogeneous distillation processes. The approach is based on the consideration of thermodynamic limiting cases, e.g., for distillation columns ∞/∞-analysis is used. The decanters are modeled using the respective liquid multi-phase equilibria. By applying an appropriate piece-wise linearization to the separatrices of the vapor–liquid(-liquid) equilibria as well as to the liquid multi-phase equilibria, the original nonlinear process model is replaced by a piece-wise linear model (Feng et al., 2003). The algorithm for the simulation of the decanters is based on a recent publication (Ryll et al., 2012a). The new short-cut method enables the analysis of flow sheets consisting of an arbitrary number of distillation columns and decanters and yields to the stream table of feasible processes. The application range of the method is further enhanced by including the units mixer, component split and split. Two examples are discussed in detail to demonstrate the application of the new method.