Experiments and mathematical modeling of maize pyrolysis in a rotary kiln

Pyrolysis of maize is experimentally investigated in a bench-scale rotary kiln in semi-continuous operation. The operational parameters varied are the temperature (450-800 degrees C), the solids residence time (7-20 min) and the solids space time (117-417 min). Mathematical modeling includes (a) the determination of suitable functions describing the material properties, (b) the selection of a reaction scheme and a formal kinetics approach in order to calculate the source terms of the balance equations, and (c) the solution of the so defined system of differential equations. Stoichiometric coefficients and formal kinetic parameters are estimated from thermoanalytic and rotary kiln experiments by regression. The results show the expected strong influence of pyrolysis temperature and a noticeable influence of space velocity. The solids residence time shows no significant influence on product yields. The model results describe well the experimental data; however, the influence of space velocity is slightly overpredicted. (C) 1998 Elsevier Science Ltd. All rights reserved.