A comparative study of thermal and combustion kinetics for raw and bio-chars of eucalyptus wood and bark

Abstract

ABSTRACT This study investigates thermal and combustion kinetics of raw and bio-char samples of eucalyptus wood and bark. Raw samples of eucalyptus wood and bark were subjected to pyrolysis at temperatures of 300, 350, 400, and 450°C. The maximum mass yield was obtained at 350°C for both bio-char samples of wood and bark. Gross calorific value, proximate, ultimate, and chemical analyses of the raw and their derived bio-chars showed high energy yield of bio-chars as compared to raw samples. Thermal analysis of raw and their respective bio-chars was also studied using thermogravimetric analysis in air at heating rates of 25, 35, and 45°C min−1. Raw wood and bark in comparison to their bio-chars showed delayed ignition that resulted in increase of ignition, peak, and burn-out temperatures. Mean reactivity of raw and bio-char samples was obtained using Ghetti model that showed higher reactivity of raw samples than bio-chars. Kinetic parameters including activation energy and order of reaction were found using Arrhenius model. For different heating rates, activation energies lied in the range of 61–108 kJ mol−1 (wood) and 42–79 kJ mol−1 (bark). Higher carbon contents in the bio-char samples resulted in higher activation energies than raw samples. This increasing carbon contents trend also furnished increase activation energies of bio-chars.