Experiment and computational fluid dynamics investigation of biochar elutriation in fluidized bed

In fluidized bed biomass fast pyrolysis, the biomass is converted to biochar and elutriated. The elutriation rate is a key parameter in reactor designs and operations. This research presents a video-based continuous measurement of biochar elutriation rate in a fluidized bed with sands and biomass as bed materials. The fluidized bed is simulated with the computational fluid dynamics-coarse-grained discrete element method (CFD-CGDEM) in MFiX. The fluidization behavior of nonspherical sands can be more accurately captured when a rolling friction model is used. The predicted elutriation rate is close to the experimental measurement when the particle size distributions are considered and the filtered drag with a shape correction is used. These results validated the accuracy of the MFiX-based CFD framework for the prediction of biochar elutriations in the fluidized bed biomass fast pyrolysis reactor.

Automated summary

This research utilized a video-based continuous measurement method to investigate the elutriation rate of biochar in a fluidized bed, simulated using computational fluid dynamics-coarse-grained discrete element method (CFD-CGDEM) in MFiX. The study found that the fluidization behavior of nonspherical sands can be accurately captured with the use of a rolling friction model, and the predicted elutriation rate closely matched experimental results when considering particle size distributions and using a shape-corrected filtered drag. These findings validate the accuracy of the MFiX-based CFD framework for predicting biochar elutriations in fluidized bed biomass fast pyrolysis reactors.