Numerical simulation and experimental analysis of a novel small scale biomass grate firing system

The presented grate firing system is a patented small scale screw burner, which is designed for high fuel flexibility. This work focuses on the numerical modelling of the boiler via CFD simulations. The in-house developed CFD models use an Euler – Lagrange approach to predict the thermal degradation of the fuel particles and the subsequent gas-phase reactions. The CFD models are validated with experimental data from a representative measurement campaign where the boiler is operated with softwood pellets and the composition of the flue gas is measured in the primary and secondary combustion zone as well as the boiler outlet. The simulation results agree well with the data acquired in the measurement campaigns.