NUMERICAL SIMULATION AND EXPERIMENTAL INVESTIGATION OF SLAGGING IN BIOMASS COMBUSTION

The Chair of Energy Process Engineering at Friedrich-Alexander-University Erlangen-Nuremberg (FAU-EVT) developed a prediction tool for slagging and fouling in biomass boilers, based on CFD simulation and verified through lab-scale experiments. Main focus lies on collision induced deposition of molten ash particles carried away from fuel bed, thus burning in the flue gas canal. Key parameters for the occurrence of slagging are the ash melting temperature, particle residence time and fuel's fine particle fraction. In combination with combustion chamber characteristics regarding flue gas velocities and wall properties, the CFD model offers an exceptional possibility for plant operators to decide on alternative biofuels. Simulation results of slagging phenomena could be verified during power plant inspection works. Furthermore an extended survey as part of a plant operators' workshop confirm our observations. In addition to CFD simulations, we performed experiments for particle combustion kinetics in lab-scale entrained flow combustion facility in order to validate boundary conditions for the combustion and slagging model.