Optimization of an Integrated First- and Second-Generation Ethanol Production Plant with Focus on Hydrolysis Parameters

Despite there are many studies regarding optimization of biorefineries in the literature, most of them modelled the hydrolysis reactor as a stoichiometric reactor with a predetermined conversion. This simplification implies loss of accuracy and lack of prediction capability, because it does not account for the dependency of hydrolysis yield with important parameters such as enzyme load, solids fraction and reaction time. In this work a kinetic model of the hydrolysis reactor is combined within the whole integrated biorefinery simulation to address this gap. The process modelling and simulation was made in EMSO. Two configurations of the second-generation ethanol (E2G) production process were simulated: the first one considering the xylose biodigestion and the second one implementing the xylose fermentation. The optimization problems involved the maximization of the Net Present Value, taking four key parameters of E2G process as decision variables. The ethanol production increase was incorporated as a constraint of the optimization problem, which was varied in a range of values to obtain optimal configurations for different scenarios. No configuration was economically feasible for the realistic economic scenario considered in the studies. However, the xylose fermentation configuration presented better economic performance than the xylose biodigestion as overall.