Dynamic behaviour of reactive distillation tray columns described with a nonequilibrium cell model

Abstract

In this paper we develop a generic, dynamic, nonequilibrium (NEQ) cell model for reactive distillation (RD) tray columns. The features of our model are (1) the use of Maxwell–Stefan equations for describing mass transfer between fluid phases, (2) the reaction is assumed to take place in the liquid phase, both within the diffusion layer and in the bulk, (3) the coupling between mass transfer and chemical reactions within the diffusion layer is accounted for, and (4) the use of multiple well-mixed cells in the liquid and vapour flow directions in order to account for staging in either fluid phase. The utility of the developed model is demonstrated by carrying out simulations of a RD column for production of ethylene glycol (EG) by hydration of ethylene oxide. The introduction of staging in the vapour and liquid phases improves the conversion to EG and also reduces the formation of the unwanted di-ethylene glycol. Furthermore, there are marked differences between the dynamic column response to feed perturbations between the developed NEQ model and the more commonly used equilibrium (EQ) stage model.