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A process flowsheet for dehydration of the ethanol-propan-1-ol-butan-1-ol-water mixture has been developed using a thermodynamic and topological analysis of the phase diagram of the system. The operating parameters of the distillation columns involved in the process have been determined, and an energy-efficient flowsheet has been chosen. [ABSTRACT FROM AUTHOR]

Shortcut methods are valuable tools in the early stages of chemical process design, where numerous flowsheet alternatives need to be evaluated to determine the most energy-efficient, feasible flowsheet. Various shortcut methods based on tray-to-tray or pinch point analysis for the inspection of feasibility and the determination of the minimum energy demand (MED) for homogeneous azeotropic distillation have been published. For multicomponent heteroazeotropic distillation, however, no generally applicable shortcut methods are available yet. In this work, various shortcut methods for heteroazeotropic multicomponent distillation are assessed. Two novel thermodynamically sound shortcut methods, the feed pinch method (FPM) and the feed angle method (FAM), are proposed to resolve the limitations of existing methods. In particular, the fully algorithmic FAM is applicable to direct, indirect, and intermediate splits for heterogeneous azeotropic mixtures of any number of components. The novel methods are illustrated by four sample separations involving ternary, quaternary and quinternary heterogeneous mixtures. The performance of the FAM is highlighted by an industrial case study, where the effectiveness of an optimization-based conceptual design of a heteroazeotropic column sequence is demonstrated. The computational efficiency of the FAM allows a numerical optimization of the operating points of flowsheet alternatives in order to determine the most energy-efficient variant. [ABSTRACT FROM AUTHOR]

• Process feasibility studies should consider a wide range of operating conditions if disturbances are likely to occur. • Combining residue curves and LLE diagrams allows a better understanding of the heteroazeotropic distillation unit. • The top vapor overcooling in the condenser and downstream decantation enhance the separation thermodynamic flexibility. When chemical processes involve the treatment of raw materials characterized by unstable properties over the year' s seasons, upstream perturbations could affect the downstream operation feasibility. This research work discusses how non-idealities can be exploited to enhance the flexibility of the operation for an ABE/W purification section. In particular, the effects of condenser overcooling on the allowed feed composition perturbations are analyzed in case of distillation process. For this purpose, an innovative methodology based on residue curve maps coupled with liquid-liquid equilibrium is presented. Calculations have been performed by means of an interface between the Simulis Thermodynamics®software for components characterization and Matlab. A graphical tool for mixtures up to four components is provided as well. This procedure extends the available methodology for the conventional distillation feasibility study by including specifications in terms of recovery ratio and by its generalization to distillation trains and Dividing Wall Columns as well. [ABSTRACT FROM AUTHOR]