Energy-Efficient Design of a Novel Double Annular Separation Column Using Pinch Pressure

This study introduces a pinch-based method to design an internally heat-integrated pressure swing distillation (HIPSD) with a double annular column. In the configuration, the annular stripping section of a low-pressure (LP) column partially wraps around the rectifying section of an inner high-pressure (HP) column to minimize exergy loss. In order to enable adequate heat transfer and azeotropic separation, the key factor is setting the pressure of the columns by considering the so-called pinch pressure, which is determined by the minimum temperature approach and circumvention of the azeotropic boundary. This heat integration between two individual columns reflects different overall heat transfer coefficients for each stage, because they are affected by the composition of the fluid and its hydrodynamic characteristics. Each column is also sized to meet hydraulic conditions to ensure separation efficiency. The HIPSD of several azeotropic mixtures was described and the maximum energy savings reached 23.80%.