MODELLING AND SIMULATION OF REACTIVE DISTILLATION TECHNOLOGY: A CASE STUDY OF ESTERIFICATION PROCESS
Reactive distillation is a chemical engineering process capable of accomplishing combination and execution of chemical reaction and separation simultaneously in a single piece of equipment. The process is very advantageous especially when exothermic reactions are involved because the heat generated from the reaction can be used to carry out the separation of the components automatically. In that case, there will be need for little or no supply of heat from an external source for the separation when operating a reactive distillation system. Also, the system presents an exciting alternative to traditional liquid phase chemical reaction processing. In this reactive distillation system, separation of products from unconverted reactants allows high conversion because product removal adjusts equilibrium and forces the reaction towards completion. In other words, the combination of reaction and distillation helps in achieving products with higher purity and higher conversion of reactants as compared to conventional processes. Consequently, there are many benefits associated with this process. However, the combination of chemical reaction and separation in the same piece of equipment has resulted into some complexities in respect of the process, and getting an appropriate model to represent the process is a challenge that chemical engineers are still working on. Therefore, this work was carried out to develop and simulate steady-state and dynamic models for a reactive distillation technology. The modelling and simulation of the technology were demonstrated using an esterification process, which is the production of ethyl acetate and water as a by-product from the reaction between acetic acid and ethanol, as a case study. The system was developed using RADFRAC distillation column model of Aspen Plus Version 11 with Non-Random Two-Liquid (NRTL) as the base method. The input parameters of the developed model were varied to generate sets of data that were used in conjunction with the System Identification Toolbox of MATrix LABoratory (MATLAB) to develop a set of dynamic models for the system. The dynamic models were used to study how the system outputs were varying with time. The good comparison observed between the results obtained and those available in the literature revealed that the developed model of the reactive distillation technology was a valid one. Also, owing to the stable steady-state outputs and dynamic responses obtained, it was discovered that the combined use of Aspen Plus and MATLAB was able to give stable models that could be simulated for this complex process successfully.