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(2017) Chemical Engineering Research and Design, 117, pp. 575-583.

Effects of reducing the reactor diameter on the dense gas–solid fluidization of very heavy particles : 3D numerical simulations

Ansart, R., Vanni, F., Caussat, B., Ablitzer, C., Brothier, M.

ABSTRACT :

- In this study, 3D numerical simulations using an Eulerian n-fluid approach of a gas–solid fluidized bed composed of very dense particles of tungsten (19,300 kg m−3) were carried out to examine the behavior of this suspension, especially the effects of the reduction of the fluidization column diameter on the fluidization quality. Tungsten was selected as a surrogate material of U(Mo) (Uranium molybdene) which is of interest for new nuclear fuels with limited enrichment. Comparisons between experiments and computations for the axial pressure profile of a 5 cm diameter column demonstrate the capability of the mathematical models of the NEPTUNE_CFD code to simulate the fluidization of this powder located outside the classification of Geldart.
- The numerical results show that the mobility into the bed of these very dense particles is very low. The reduction of the fluidization column diameter from 5 cm to 2 cm does not have significant effect on the local solid circulation but strongly decreases the axial and radial mixing of the particles due to wall-particles friction effects. These results confirm and allow to better understand the wall effects experimentally evidenced. © 2016 Institution of Chemical Engineers