Mathematical modelling of gasification and combustion of solid fuels and wastes

Gasification of solid fuels is nowadays a promising alternative to direct combustion. This work presents a general mathematical model of gasification and combustion units where both the transport resistances and the chemical kinetics are important at the particle scale. Pyrolysis and devolatilization of the solid fuel is only the first step of the entire process. Successive gas phase reactions of the released species require both a proper description of the gas-solid transport equations as well as the characterization of gas-solid combustion and gasification reactions. At the reactor scale the numerical complexity of the resulting problem derives first of all from the large number of involved species and reactions and also from the stiff nature of the overall system. A Couple of examples relating to coal combustion and biomass gasification allows the evaluate the possibility and limitations of the proposed approach.