Inferential Control of Fuel Additive Purity via Reactive Distillation Process

Abstract

In this work, the control of the mole fraction of a fuel additive being produced in a reactive distillation column has been carried out using proportional-integral-derivative (PID) control. The fuel additive considered in this case was isopropyl alcohol, which was produced from the reaction between propylene and water. To accomplish the work, a ChemCAD model of the process was first developed and simulated to convergence before it was converted to dynamic type from which the dynamic responses of the system were generated and used, with the aid of MATLAB, to develop a transfer function model having the reboiler duty, the reflux ratio and the temperature of the bottom product as the input, the disturbance and the output variables of the process, respectively. The obtained transfer function model was used to develop the open-loop and the closed-loop Simulink models of the process that were also simulated. The closed-loop simulation was carried out with the objective of achieving a fuel additive product with a mole fraction of 0.97, and this was done using a PID controller that was applied inferentially via the product temperature. The results obtained showed that the control of the fuel additive mole fraction could be achieved inferentially, with PID controller tuned with Cohen-Coon and Simulink approaches, using product temperature.