Graphical optimization method for coupled heat exchanger network and reactor

In chemical process industry, the reactor's operating parameters (conversion and selectivity) affect their temperatures, as well as the integration of the Heat Exchanger Network (HEN). It is necessary to consider the integration of the HEN and the optimization of the reactor parameters simultaneously. A Pinch-based method is developed to integrate HEN and optimize the inlet and outlet temperature and energy consumption of reactors with multiple reactions. Based on the reaction kinetics, mass balance and energy balance, equations are deduced to show relations among temperatures, selectivity and conversion of reactor, energy consumption and the energy consumption of unit production. According to the Composite Curves, the effect of temperature variation on HEN is analyzed for exothermic and endothermic reactions, respectively, and relations among temperatures, selectivity, utilities, energy consumption of unit product and conversion are deduced and plotted in the same diagram. The optimal utilities, inlet/outlet temperature, selectivity and conversion of the reactor can be identified from this diagram. A benzene to cyclohexene process is studied to illustrate the application of the proposed method, and the result shows that the energy consumption of unit product can be reduced by 16.3% when the conversion of benzene is increased from 0.4 to 0.58.