Dynamic simulation of the multicomponent reactive distillation

A dynamic mathematical model of reactive distillation in case of kinetically controlled chemical reaction is formulated using four basic assumptions: negligible vapour holdup compared to the molar liquid holdup, perfect mixing of phases, corrections of equilibrium values by plate efficiency, corrections of conversion for mixing effects by 'conversion efficiency'. The accuracy of the dynamic simulation results of reactive distillation obtained under different assumptions is verified by comparing with results of actual experiments on a pilot-scale distillation column. Both the unsteady-state period during start-up and the disturbances of continuous operation are considered. Esterification of ethanol with acetic acid with sulphuric acid as homogeneous catalyst is chosen for experiments. Accuracy of simulation is very good in case of model containing hydraulic description of plates with regard to temperatures inside column and in the reboiler. Responses of component concentrations are less accurate, but imposed disturbances were very large. Observed differences result from simplifications of mathematical model, inaccuracy of the kinetic and vapour-liquid equilibrium description for highly nonideal, multicomponent system and from precision of experimental measurements in case of transient state. Differences between experimental and simulation results in case of different models are the most significant for large holdup on plates in comparison with reboiler. As a general rule, in case of reactive distillation simulation for dynamics, description models taking into consideration plate hydraulics should be used. Copyright (C) 1996 Elsevier Science