CFD-DEM Investigation of Fuel Dispersion Behaviors in a 3D Fluidized Bed

In this paper, dispersion behaviors of continuous-feeding fuel particles in a 3D fluidized bed were studied in detail using CFD-DEM simulations with a substantial difference in particle properties between the fuel and bed material, as well as the dynamic fuel-feeding process being reasonably considered. By quantitively evaluating the dispersion characteristics of fuel particles, the effects of key factors including the fluidization velocity, initial bed height, and the particle properties of fuel and bed materials on the dispersion behaviors of fuel particles were comprehensively examined with the motion and distribution of fuel particles being discussed in detail. The results indicated that crucially dominated by the bubble behaviors, the axial dispersion coefficient of fuel particles is 1-2 orders-of-magnitude larger than that in the radial direction in the fluidized bed. Increasing the fluidization velocity obviously promotes the dispersion and thus the uniformity distribution of the fuel particles. More intense axial dispersion of fuel particles appears with the higher initial bed height, under which conditions the axial distribution uniformity of fuel particles is efficiently improved. On the other hand, using the finer bed material enhances the fuel dispersion at the same fluidization velocity but instead weakens the dispersion at a similar fluidization number. Furthermore, the low-density fuel particles have a larger dispersion coefficient, which can be mainly explained by their preferential distribution behavior in the dense bed surface region.

Automated summary

This paper investigates the dispersion behaviors of continuous-feeding fuel particles in a 3D fluidized bed and identifies key factors influencing the dispersion. The axial dispersion coefficient of fuel particles is found to be significantly larger than the radial dispersion coefficient, with increasing fluidization velocity and initial bed height promoting dispersion. However, using finer bed material enhances fuel dispersion at the same fluidization velocity but weakens dispersion at a similar fluidization number.