Modelling the Degradation of Particles in Fluidised Beds: Drying, Pyrolysis and Fragmentation

This work focuses on modelling the degradation of particles in gas-solid fluidised beds. Modelling is performed by using a coupled approach where the gas phase is treated as a continuum and the solid phase is represented by individual discrete particles, using the discrete element method (DEM). This approach makes it possible to access individual particle properties. By implementing new modelling techniques into the DEM framework, the individual particle degradation behaviour can be numerically described with high accuracy. The main interest is to understand more complex gas-solid systems as encountered e.g. in fluidised beds which might contain numerous degrading particles. This work focuses on verifying and validating these sub-models to be able to obtain accurate information for further suggestions in operation and optimisation of dense particulate systems. Particle degradation is studied by means of thermophysical (drying), thermochemical (pyrolysis) and mechanical (fragmentation) aspects.