9-38: Modeling temperature variations in a pilot plant thermophilic anaerobic digester

A model that predicts the changes of temperature in a pilot plant anaerobic digester was developed. The pilot plant, working under thermophilic conditions, was previously described by our research team (Espinosa-Solares et al., App. Biochem. Biotechnol. (129-132):959-968, 2006). Mass and energy balances under steady and unsteady conditions were applied to develop the model, which was parameterized based on data obtained from bioreactor actual operation routines conducted under different heating strategies. To validate the model new experimental routines were applied for different feed-loading frequencies and also process was simulated by solving equations numerically. The comparable simulated and experimental data allowed accepting the validity of the model. A sensitivity analysis established that the most important causes of the cooling of the mass inside the tank were the heating of the feed and the exit of the effluent.

Keywords: Modeling, Temperature prediction, Mass and energy balances, Overall heat transfer coefficient.