Char Reactive Processes: Diffusive, Kinetic and Reactoristic Aspects

Once the devolatilisation process is over, the biomass char particle is ready for the thermoconversion stages. Before going into the details of combustion and gasification (and related aspects), this chapter conceptually presents the diffusive, kinetic and reactoristic aspects related to heterogeneous processes involving char and a gaseous oxidising agent. The shrinking core model and the shrinking particle model will be presented, with analysis of the possible controlling regimes. The characterising equations will be obtained with reference to the main chemical-physical parameters involved. We will then move from the scale of the particle to that of the chemical reactor, showing the general design equations and addressing some case studies of interest in industrial practice.