Kinetics of Pyrolysis of Mesquite Fuel: Comparison of Different Methods

Abstract

Recently Torrefaction processes are used to improve the quality of fuels. Upper limit on torrefaction temperature can be determined using the maximum volatile release method (MVR) in deducing the kinetics of pyrolysis. The single reaction model (SRM), parallel reaction model (PRM also known as distributed reaction model) and three component models (TCM for hemicellulose, cellulose and lignin) of pyrolysis are briefly reviewed. The MVR method uses the maximum volatile release rate conditions for extracting the kinetics of pyrolysis. Thermogravimetric (TGA) and Differential Thermal (DTA) analyses for mesquite biomass were performed in a thermo-gravimetric instrument and particularly the pyrolysis data of the mesquite samples from MVR are compared with those of SRM and PRM. The focus of current paper is on the extraction of kinetics data (activation energies and pre-exponential factors) from various methods: MVR for the SRM (called as SRM-MVR), PRM and SRM-CA and on the comparison of experimental data with model predictions from SRM-MVR, SRM-CA and PRM for mesquite fuel. It was found that the SRM-CA displays the largest error to predict the mass loss, and SRM-MVR generated less error than SRM-CA even though the kinetics data for SRM-MVR were extracted using a single point. The predicted pyrolysis behavior from the PRM exhibits the best agreement for the whole domain of pyrolysis but peak point which is of importance in torrefaction process is not predicted well. Particularly the kinetics data generated with SRM-MVR is useful in estimating the upper limit on temperature of torrefaction for biomass fuels.