Reactive distillation for methanol synthesis: Simulation-based design methodology

A simulation-based design methodology for configuring a reactive distillation (RD) column for methanol synthesis is presented in this work. Unlike other processes using RD, all the reactants involved in methanol synthesis are gaseous and, therefore, the conventional methods used for the design of RD columns cannot be used. The simulation-based design algorithm also gives better insights into the process. RD for methanol synthesis requires an inert solvent and the column configuration has side coolers on the stages to remove the heat of reaction. The developed algorithm aims to maximize the methanol production, while minimizing the solvent requirement and the number of side coolers. The methodology has been demonstrated for three different feed syngas compositions. It is observed that the performance of RD is either at par with, or superior to, the conventional process for the studied cases. A multi-parametric sensitivity analysis shows that the solution obtained using this design algorithm is within 0.3% of the local optimum. The effect of solvent flowrate on the column sizing and economics and the possibility of multiple steady-states is also illustrated.