Computational Fluid Dynamics Modeling of Pulverized Biomass Combustion
Niko Niemelä*, Teemu Saarinen, Henrik Tolvanen, Aino Leppänen, Antti Oksanen
Tampere University of Technology
Department of Chemistry and Bioengineering
*niko.p.niemela@tut.fi
Abstract: The aim of this research work is to evaluate the functioning of the standard Computational
Fluid Dynamics (CFD) pulverized coal combustion models for biomass combustion. The mass-loss of
two biomass fuels is determined experimentally with a Drop-Tube Reactor (DTR) and the
devolatilization and char combustion reactivity parameters are fitted to the experimental data using
the same models as in the commercial CFD software ANSYS Fluent. In the experiments, it is found
that the oxygen concentration has an effect on the particle conversion. This indicates that the
assumption of consecutive combustion stages in CFD models does not hold for biomass particles and
the devolatilization and char combustion stages may overlap. A CFD model of the DTR is constructed
and the particle combustion process is modeled using the determined reactivity parameters. It is
found that the standard CFD models give satisfactory results, but the predictions could be improved
by using a variable particle volatile yield and allowing simultaneous combustion stages.