Intra-pellet transport limitations in the pyrolysis of raintree leaves litter

Pyrolysis of biomass pellets is a complex process that is generally influenced by internal transport limitations. For the better understanding of these effects, a rigorous fully transient 1-D mathematical model for a single pellet was developed that includes unsteady state mass and energy conservation equations for gaseous and solid species. The heat transfer within the pellet is mainly due to conduction whereas, convection and radiation play a significant role in the heat exchange between the pellet surface and the reactor wall. The model involves set of partial differential equations which can be solved for two different cases viz. a reactor with constant wall temperature and a non-isothermal reactor wall with constant heating rate. The formulated equations are solved using MATLAB by converting them into a set of algebraic equations using discretization technique. The resistances due to transport limitations within the pellet are quantified in terms of effectiveness factor. The effectiveness factor was found to be dependent on pyrolysis heating policy, pellet thickness, and thermal conductivity. [Display omitted] •Intrinsic kinetics data is generated for pyrolysis of Raintree leaves.•A transient 1-D mathematical model is developed for pyrolysis of a biomass pellet.•The model predictions at pellet level agree well with the experimental results.•Heat transfer resistances are quantified in terms of effectiveness factor.•Effectiveness factor depends on heating rate, pellet radius, and thermal conductivity.