Assessing different alternatives by simulation to optimize a homogeneous transesterification process to improve the produced/consumed energy

A conceptual biodiesel production homogeneous process was developed, considering the typical reaction conditions, appropriate thermodynamic models as well as the kinetics of a representative reaction for vegetable oils, under assumption to be mass-produced and provide a continuous way the raw material for the production of the biofuel. Reasonable assumptions and the use of a rigorous simulator of processes were employed; the process was simulated for the treatment of 1000 mol/h of oil operating continuously, at 45 and 55 degrees C, 1.0 wt% catalyst and 6 mol methanol by mol of oil. The processes of catalyst preparation, raw material pumping, heating, isothermal reaction, separation of byproducts by density and distillation were considered, and also auxiliary services of heating and cooling during the process. The convergence of each device was achieved by properly choosing the specifications of the unit operation models. Material and energy balances were obtained at each point in the process and in a global manner. For space-time of 30 min in single and series reactors global efficiencies from ~80 to 85% biodiesel was calculated for all explored alternatives. The ratio of energy production of biodiesel to the energy consumed by the process, within the battery limits used in this study, was found to be more than 6 times, thus ensuring the sustainability of the process from energetic point of view. It was found that, for the highest purity and better ratio of energy produced/consumed, the global efficiency process was the lowest.