(555a) Modeling of a Continuous Two-Phase Bubble Column Reactor for the Production of Biodiesel From Free Fatty Acids

Cairncross, R. A., Drexel University
Mohammed, M., Drexel University
Melick, C., Drexel University

A continuous reactor model has been developed to optimize the performance of a two-phase bubble column reactor for biodiesel production from oils with high free fatty acid content using acid catalyst. The model accounts for the esterification reaction kinetics, thermodynamics and mass transfer limitations associated with the dynamics of methanol and water between vapor and oil phases. The reactor model is a set of differential mass balances for each species in each phase and contains characteristic parameters which can be manipulated under steady state to investigate operating regime of the reactor. The model parameters are estimated based on transient model results from a set of parametric studies consisting of feed temperature; alcohol feed quality, feed flow rates, agitation intensity and baffle design. The model enables optimization of the reactor design and operating conditions with fewer experiments. A finite difference method has been employed to solve the model and predict both transient and steady-state species concentration profiles inside the reactor. The model will be extended to capture the effects of simultaneous esterification and transesterification reactions inside the same reactor so the model can be applied to a variety of feedstock. The model predicts conversion profiles observed in experiments with varying flowrates of oil and alcohol feeds. Also, the model predicts the effect of feed quality (e.g. presence of water in the feed alcohol) on overall reactor conversion.