Design and Control of Reactive Distillation System for Esterification of Levulinic Acid and n-Butanol

This work presents the conceptual process design and the associated control strategies for the manufacture of n-butyl levulinate, which can be a suitable fuel additive, because of its high octane number, high oxygen content, and low water solubility. A reactive distillation column is used to avoid problems of separation and equilibrium reaction in the conventional esterification process. Both the thermodynamic properties and the kinetic data are compiled from open literatures. Sensitivities of several key design variables, including the feed ratio of raw materials and operating pressure of the reactive distillation column, to the economic manufacturing of n-butyl levulinate are investigated. The optimal steady-state design is found through total annual cost analysis, using iterative optimization procedure. Two feasible control structures are presented for this reactive distillation process. A series of simulations shows that both of the control strategies can reject throughput disturbances quite well, but can only achieve ordinary control performance for handling the feed composition disturbances.