Thermodynamic Analysis of Coupled Reaction-distillation Processes: Conceptual Design, Modelling, Simulation and Experimental Validation

Conceptual process design requires screening many alternatives, but rigorous simulation of complex flowsheets with recycles is often too slow and may miss multiple steady states. This work presents a shortcut method based solely on fundamental thermodynamics to analyze arbitrary flowsheets of reactors, distillation columns, and decanters using minimal inputs (property models, flowsheet structure, feed streams, and product specifications). Distillation feasibility is treated via c°/c° analysis, reactors are modeled either at chemical equilibrium or with specified conversion, and decanters are described through liquid–liquid and multiphase equilibria. Nonlinear equilibrium manifolds (VLE, chemical equilibrium, LLE, multiphase liquid equilibrium) are replaced by piecewise-linear representations, enabling the overall process to be formulated as underdetermined linear equation systems with linear inequalities solvable robustly by linear optimization. A software tool implementing these methods is developed and can be coupled to external property packages (e.g., Aspen Properties), with the current implementation restricted to systems of up to four components to allow composition-space visualization. The work details algorithms for generating piecewise-linear equilibrium diagrams, including an evolutionary approach for VLE and a general procedure for chemical equilibrium; for LLE and multiphase equilibria, a new Gibbs-energy-based Convex Envelope Method is introduced, validated against experiments and rigorous decanter simulations. The tool is demonstrated on industrially relevant cases such as ETBE and n-butyl acetate production, and its results can provide reliable initial guesses for rigorous simulation; a prototype supported development of a new distillation-based trioxane process. The approach can also aid reactive distillation analysis by studying equivalent conventional schemes and, in principle, can be extended to reactive VLE within c°/c° analysis. In addition, the work reports thermophysical data, modeling, simulation, and experimental validation for reactive dividing wall columns within the EU project INSERT, using heterogeneously catalyzed methyl acetate hydrolysis (Amberlyst 48) as a test system. High-quality VLE (NRTL parametrization) and activity-based kinetics are established from 31 plug-flow experiments (50–70 °C), and industrial-scale trials in a 220 mm reactive dividing wall column at Sulzer Chemtech confirm stable operation. Equilibrium-stage simulations including kinetics reproduce the industrial data, with liquid/vapor split around the dividing wall identified as the key design parameter, indicating that established design concepts for heterogeneously catalyzed reactive distillation can be transferred to reactive dividing wall columns.