A CFD model that simulates the combustion of biomass in existing pf coal fired furnaces has been developed and model results for the combustion of a typical wood in a I MW industrial test facility have been presented. The model is primarily based on coal combustion submodels using an Eulerian-Lagrangian frame of reference. Biomass specific constants that define the submodels have been investigated and employed in the simulation. In particular, potassium release during biomass combustion and the formation of NO, have been simulated. Numerical predictions have been compared with some experimental measurements that have been taken and reasonably good agreement has been achieved. (c) 2006 Elsevier Ltd. All rights reserved.