(85b) An Energy-Efficient Double Annular Column for Azeotropic Separation

This study presents a novel approach to design an internally heat-integrated pressure swing distillation (HIPSD) as a double annular column with a pinch-based method. The proposed configuration involves the annular stripping section of a low-pressure (LP) column partially wrapping around the rectifying section of an inner high-pressure (HP) column in order to minimize exergy loss. To achieve adequate heat transfer and azeotropic separation, the pinch pressure is determined by considering the minimum temperature approach and circumvention of the azeotropic boundary. The heat integration between the two columns accounts for the overall differences in heat transfer coefficients for each stage, which are affected by the composition of the fluid and its hydrodynamic characteristics of each stage. Additionally, each column is sized to meet hydraulic conditions for optimal separation efficiency. The HIPSD design for several azeotropic mixtures was designed with maximum energy savings of up to 23.80%.