APPARENT KINETIC MODELLING OF TORREFACTION BEHAVIOUR AND AXIAL VARIATION IN PINUS CARIBAEA AND LEUCAENA LEUCOCEPHALA UNDER REACTOR-SCALE CONDITIONS
Torrefaction improves the fuel properties of woody biomass. This study investigated kinetics of torrefaction-induced weight loss in Pinus caribaea and Leucaena leucocephala grown in Nigeria, between 225–300°C and axial stem position (top, middle, base). Oven-dried samples (300 g) were torrefied in a fixed-bed reactor under oxygen-limited conditions. Apparent rate constants were derived using a pseudo-first-order Arrhenius model. A total of 72 experimental runs were conducted. The sample weight loss increased with temperature. Pinus caribaea exhibited higher rate constants (0.0136–0.0761 min⁻¹) and lower activation energies (48.6–56.8 kJ.mol⁻¹) compared to Leucaena leucocephala. Axial variation significantly influenced activation energy, with base sections exhibiting 15–22% higher values than top sections. These findings demonstrate that biomass heterogeneity strongly affects reactor-scale torrefaction kinetics and should be considered in feedstock selection, process optimisation, and industrial-scale thermochemical conversion systems.