PACKED BED COMBUSTION MODELING: A PROPOSED METHODOLOGY FOR INDUSTRIAL BIOMASS GRATE BURNERS

摘要

In this paper, a new approach for the combustion modelling of thick particles in a packed bed isrnpresented. This research work is mainly devoted to an industrial application, so it requires an adequate balancernbetween computational costs and accuracy. Consequently, the fuel bed is idealized as a porous medium with arnconstant volume and the different reactions that represent the particles combustion (drying, pyrolysis and charrnconversion) take place on its specific surface area. Over the bed, the gaseous species released during pyrolysis andrnchar reactions are oxidised thanks to the secondary air supply. Accordingly, a set of nine equations is applied for thernentire domain (fuel bed and freeboard) and each reaction rate is expressed under an Arrhenius form. Summing up, thernmethodology described in the present paper aims to investigate the modelling possibilities of packed bed combustionrnof solid biomass, which is not yet directly implemented in available CFD softwares. The results will be furtherrnvalidated for a medium-scale grate boiler, a promising firing technology for heat supply in both domestic andrnindustrial sectors, based on biomass combustion.