Biomass furnace study via 3D numerical modeling

In the recent years the interest toward the use of biomass as a fuel for energy conversion, along with the continuous tightening of regulations, has driven the improvement of accurate design techniques which are required to optimize the combustion process and simultaneously control pollutant emissions. In this paper the use of a 3D Computational Fluid Dynamics approach is analyzed to that aim by means of an application to an existing 50 MW biomass fixed-bed combustion furnace fueled by grape marc. The paper aims to discuss these issues.

The studied furnace is an interesting example of biomass utilization as it may integrate biomass with organic residual by an industrial process. The numerical model has been implemented into an OpenFOAM solver, with an Eulerian-Lagrangian approach. In particular, the fully 3D approach here presented, directly solves for the gas and solid evolution in both the combustion bed and the freeboard. Special care has also been devoted to the treatment of radiating fluxes, having a remarkable influence, again, on the bed evolution.

Results have been compared to experimental data in terms of temperature showing a good agreement. Further comparisons have been done with literature available data for a similar power size biomass furnace showing reasonable similarities.

Emission formation processes in a biomass furnace are dealt with in this paper. The innovation lies in the use of a fully 3D numerical approach, that is validated with regard to temperature measurements gathered in a multi-MW experimental furnace.