Non-catalytic heterogeneous combustion and gasification reactions modeling for a single char pellet

The objective of the present study was to analyze the gasification process for the simultaneous exposure to a multi-component gasifying mixture. In a real scenario of the gasification process, char pellets from the pyrolysis zone undergo multiple non-catalytic gas-solid reactions in combustion and gasification zones. A single-char pellet gasification and combustion is studied in this study. This was done by developing a mathematical formulation, based on a grain model, for multiple reactions that also incorporated transient and non-isothermal behaviors, structural changes, and porosity changes. The developed model was validated against experimental data from the literature and was in good agreement. The variation of conversion, gasification reactivity, species' effectiveness factor, and reactions' effectiveness factor for various parameters were analyzed. Out of these parameters, bulk temperature, initial condition for temperature, pellet radius, and diffusivity of the gases were found to have a profound impact on the effectiveness factor of the species.