Simulation and Control of Reactive Distillation of Biodiesel Production

Abstract

The control of the transesterification process was conducted using MATLAB® codes as well as its Simulink environment. To realize the aim of the study, the dynamics data of methyl-oleate (BIODIESEL), decanter duty (manipulated variable) and reflux ratio (selected disturbance variable) were elicited from the Aspen Plus®. dynamic simulation of the formulated process model and this was used to get the first-order-plus-dead-time transfer function relation between methyl-oleate, decanter duty and reflux ratio with the help of MATLAB®. Open loop simulation was achieved by introducing steps to the input variables (reboiler duty and reflux ratio). The feed oil (Trolein) (98.3%) was converted into methyl-oleate and the final composition of the exit streams was 72.9% methyl-oleate, 1.7% triolein, 24.5% glycerol, 1.3% purge methanol. It was observed that a net duty of 5kW is required to achieve this production after 6000 mins at 100 °C. The controller was successfully tuned by Zeigler-Nichols (ZN) and Cohen-Coon (CC) techniques to conduct the disturbance rejection of the process. The performance of the CC tuning and ZN adjusting techniques in the disturbance rejection control simulation had Integral Square Error (ISE) and Integral Absolute Error (IAE) values of 1.269/ 4.09 and 1.126/3.909, respectively. It was noticed that the performance of the CC tuning technique was better than that of the ZN tuning technique in the disturbance rejection control simulation due to its lower ISE and IAE values. This study suggested that the reactive distillation process could be effectively operated to act as required using PID control to produce clean methyl-oleate.