Großtechnische Validierung eines CFD-Modells in Verbindung mit einem Brennbettmodell für die thermische Abfallbehandlung in Rostfeuerungsanlagen

Numeric modelling and simulation by means of Computational Fluid Dynamics (CFD) to describe the flow processes in waste combustion are regarded as state-of-the-art and are in successful, widespread use. A basic pre-condition for CFD simulation of the gas phase of a boiler is the provision of exact initial values by means of a suitable fuel-bed model. Of primary interest in simulation are the practical implementation and therefore the validity of the model calculations. In the project described here covering overall validation on an industrial-scale waste-to-energy plant, the development of a fuel-bed model yielded improvements in the basic boundary conditions for CFD simulation. Comprehensive measurements of temperatures, flue-gas concentrations and speeds were performed and compared with simulated values. Using the model approaches selected it was established that the model for CO burn-out and for a number of other simplified partial models, such as heat dissipation in the convective area of the heat exchangers, did not permit accurate analysis or forecasting for these sub-areas. However, good matches were achieved, in particular with regard to temperature and flue-gas concentration values for CO 2 and O 2. There were some mismatches in the speed components due, above all, to the turbulence prevailing in the first pass of waste-to-energy plants. Nevertheless, it was possible to identify tendencies.