Modelling non-isothermal kinetics of biomass prepyrolysis at low pressure

The object of this work was the investigation of the kinetics of wood sawdust prepyrolysis. The thermochemical decomposition of the sawdust took place between 250 and 450°C in a laboratory reactor of which the basic thermal characteristics were also studied. The experimental results were processed by non-linear regression. Both degradation and charification were found to follow first order reactions. The activation energies of the degradation and charification reactions were estimated at 111 and 68•7 kJ/mole, respectively. Furthermore, proximate analysis of the partially charified solid product has shown that the volatile matter content of the solid biofuel produced was reduced by 35% after the process, whereas its gross calorific value was increased by 17%.