CFD–DEM modeling of O2/CO2 char combustion in a fluidized bed

Abstract

This paper describes a CFD–DEM modeling of char combustion in a bubbling fluidized bed (BFB) under both O2/CO2 and O2/N2 atmosphere. The char combustion model under O2/CO2 atmosphere is based on our previous work of oxy-fuel combustion of a single char particle. Different mole concentrations of O2 in the inlet gas mixture are studied. The result indicates that the small bed materials restrict the mass transfer from bed to the surface of char particles when they are deep into dense phase. The distribution of reactive gases (O2,CO2, CO) in the bed does not show much difference when the O2 mol concentration is 21 % in the inlet gas between O2/N2 and O2/CO2 atmosphere, but gasification of char should not be ignored when the inlet O2 mol concentration is up to 30 % in O2/CO2 atmosphere.