Simulation and optimization of reactive packed distillation column for biodiesel production using heterogeneous catalyst

Abstract

It is important to simulate a process to see how its production would be in real time. However, there is a few simulation study in literature on continuous flow-biodiesel production in reactive distillation (RD) column. In this study, simulation and optimization of continuous flow-biodiesel (FAME) production in RD column packed with cheaper heterogeneous basic CaO catalyst by using Aspen HYSYS 3.2 software was investigated to contribute to the literature. In study, low-priced waste cooking oil (WCO) and methanol were fed separately into first stage at top of RD column. In the literature, transesterification was considered as pseudo-first order forward reaction, and activation energy (Ea) and frequency factor (A0) for WCO of 79 kj/mol and 2.98 x 1010 min-1 were determined, respectively. After discovering composition of WCO by GC, a set pseudo-first order forward reaction based on triglyceride (as tripalmitin, tristearin, triolein and trilinolein) were written to the simulator. The developed model using General NRTL fluid package was simulated to converge by Sparse Continuation Solver. After simulation, optimum conditions were determined by Optimizer tool and Box algorithm. In the optimization, objective function was selected so as to maximize the sum of conversion and mole fraction of m-oleate in bottom product. As a result, optimum values were determined as reflux ratio of 0.1, reboiler duty of 17.9 W, total feed flow rate of 11.2x10-4 kgmol/hour and methanol/WCO molar ratio of 6.42 for maximum conversion of 99.97% and mole fraction of 70.69%. Consequently, good results were very compatible with literature, thus showing suitability of suggested model, economically feasible biodiesel production and Aspen HYSYS 3.2 capability of handling this process successfully.