Optimization of methanol synthesis and cyclohexane dehydrogenation in a thermally coupled reactor using differential evolution (DE) method

This paper presents a study on optimization of a methanol synthesis and cyclohexane dehydrogenation in a thermally coupled reactor. A theoretical investigation has been performed in order to evaluate the optimal operating conditions and enhancement of methanol and benzene production in a thermally coupled reactor. Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes and reduces the size of the reactors. In this work, the catalytic methanol synthesis is coupled with the catalytic dehydrogenation of cyclohexane to benzene in a heat exchanger reactor formed of two fixed beds separated by a wall, where heat is transfer-red across the surface of tube. A steady-state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The co-current mode is investigated and the optimization results are compared with corresponding predictions for a conventional (industrial) methanol fixed bed reactor operated at the same feed conditions. The differential evolution (DE), an exceptionally simple evolution strategy, is applied to optimize methanol and benzene synthesis coupled reactor considering methanol and benzene mole fractions as the main objectives. The simulation results have been shown that there are optimum values of initial molar flow rate of endothermic stream and inlet temperature of exothermic and endothermic sides to maximize the objective function. The optimization method has enhanced the methanol mole fraction by 3.67%. The results suggest that optimal coupling of these reactions could be feasible and beneficial. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.