A Coupled CFD-DEM Approach to Model Reactive Granular Beds

Packed and moving bed reactors are widely used in process industry to process granular material. Shaft furnaces are one example of this. Due to their counterflow layout, a high thermal efficiency can be achieved. Shaft furnaces have a wide range of length and time scales that makes them challenging to model. Geometric details, like injection nozzles, are smaller than the particle size, which need a computationally highly expensive resolved Discrete Element Method (DEM) approach. To overcome this problem, a computing technique called Volume Fraction Smoother (VFS) was developed. Since the time scales in those systems reach from milliseconds for the particle collisions to hours of process time, the process time scale must be separated to model a quasi-steady state with reasonable computing time. For this, the Time Scale Splitting Method (TSSM) was introduced. This method was also adapted to model the self-heating behaviour of direct reduced iron (DRI).