Monday, April 30, 2007

Consecutive reaction model for the pyrolysis of corn cob

Fei Yu, Roger Ruan, and Paul Chen. Department of Bioproducts and Biosystems Engineering, University of Minnesota, 1390 Eckles Ave, Saint paul, MN 55108

The development of biomass pyrolysis technology is technically hindered by the type and quality of pyrolysis reactor. The quality of the pyrolytic liquid depends on the operation conditions and the types of pyrolysis. Improving the performance of the pyrolysis reactor requires a profound understanding of the various phenomena that take place during the pyrolysis process. This information is essential to the optimum design and operation of the pyrolysis. In general, kinetic modeling has become a valuable tool and was widely used for process design and control, especially for a multitude of different chemical processes. Fundamental information of rate constants of primary reactions is a key to the success of such modeling. This knowledge however is not available for the reactions involved in biomass decomposition. The objective of this research is to apply a consecutive reaction model in the kinetic evaluation of the thermogravimetric data. Detailed information on the pyrolysis characteristics and chemical kinetics of corn cob was obtained. A thermogravimetric analysis including determination of kinetic parameters was performed at a constant heating rate of 10 - 30 K/min. The effect of the heating rate and particle size on the pyrolysis behavior was discussed. One-step global model and two-step consecutive-reaction kinetics applied to corn cob are generally intended to predict the overall rate of mass loss. Although various chemicals are released during pyrolysis, global kinetics are looked to as offering a clue to the key mechanistic steps in the overall degradation process of corn cob.