Synthesis of Separation Systems for Azeotropic Mixtures: Preferred Distillation Region

摘要

An algorithm for automatic generation of sequences of distillation columns and decanters for separation of azeotropic mixtures has been developed where distillation boundaries can be crossed by moving them with pressure change, by exploring curvatures of distillation boundaries or by liquid-liquid splits in decanters. Based on a broad knowledge of distillation regions and distillation boundaries for the separated mixture, open-loop sequences are generated and primary recycles are automatically detected. Then preferred distillation regions are identified and suitable recycle streams are selected. In this paper, we are focused on internal secondary recycles where species present in the sequence feed are introduced as separating agents. This type of recycles can simplify tremendously the whole sequence and reduce significantly the total cost of separation. In this paper, an example based on an industrial case is presented where the internal secondary recycle was automatically calculated during synthesis of column sequences.