Investigating the Effects of Operating Parameters of a Reaction Integrated Distillation Process for SAME Production Using Aspen PLUS

The effects of some operating parameters of a reaction integrated distillation process used for the production of a biodiesel type have been studied in this research work. The operating parameters considered were reflux ratio and reboiler duty while the biodiesel type produced was stearic acid methyl ester (SAME) that was obtained from the esterification reaction between stearic acid and methanol. The production of the biodiesel was accomplished theoretically with the aid of a process simulator known as Aspen PLUS using RadFrac column that had 32 stages including the condenser and the reboiler and that was divided into three (rectifying, reaction and stripping) sections, excluding the condenser and the reboiler. The reaction was taken to occur in the middle, which was the reaction section of the column as well as in the reboiler. In order to study the effects of the operating parameters, both simulation and sensitivity analysis of the process were carried out using the process simulator. Based on the observations of the simulation and the sensitivity analysis, optimization was carried out also using Aspen PLUS. The results obtained revealed that separate variations of reflux ratio, from 1 to 10, and reboiler duty, from 0.1 to 1 kW, while keeping other simulation parameters constant yielded a bottom product with very high purity SAME at a reflux ratio of 1 and a reboiler duty of 0.1 kW. However, the combination of these values of the operating parameters could not converge when used to run the developed model of the process. Furthermore, using the optimum values of the reflux ratio and the reboiler duty that were estimated to be 2.23 and 0.90 kW, respectively to run the developed process model, SAME mole fraction of 0.9993 was obtained from the bottom product of the column. Therefore, it has been discovered that each of reflux ratio and reboiler duty separately affects the operation of the reaction integrated distillation process, but considering their combined effects simultaneously and optimizing are very necessary in order to achieve very high purity of the desired product.