In this work, the hydrodynamic characteristics in slugging fluidized beds were simulated by using computational fluid dynamics (CFD) code. Considering the existence of cohesive inter-particle forces which could result in larger effective particle sizes and hence reduced fluid?particle drag forces in Geldart A particles, based on the theory of gas-cluster model and the experimental data, an effective mean particle cluster diameter was used to modify the Gidaspow drag force model. Based on the Eulerian?Eulerian two-fluid model which was integrated with the kinetic theory for solid particle, the numerical simulation of the gas?solid fluidized bed after modifying the drag model showed that the modified drag model can accurately and reasonably simulate the slugging characteristics of fluidized bed through the comparison of experimental results and empirical formulas. In the range of superficial gas velocity Ug=0.09~0.39 m/s, the standard deviation of the differential pressure fluctuation inside the bed increased with the increase of Ug, which corresponded to the change of flow pattern from bubbling to slugging until to the maximum stage of slugging. The gas?solid flow in the bed was mainly affected by the motion characteristics of the axial slug. The pressure drop, the expansion ratio of the bed, the average rising speed of the slug, and the maximum length of axial slug increased with the increase of Ug, and the position of the maximum axial slug decreased as Ug increased. When Ug exceeded 0.39 m/s, the standard deviation of the differential pressure fluctuation inside the bed decreased with the increase of Ug, which corresponded to the change of flow pattern from the weakening of slugging until to the turbulent. The gas?solid flow in the bed was mainly affected by the motion characteristics of the wall slug. The pressure drop, the expansion ratio of the bed, the average rising speed of the slug, and the maximum length of axial slug decreased with the increase of Ug, and the position of the maximum axial slug increased slightly as the Ug increased.
Shuhui MA Ruojin WANG Dewu WANG Yan LIU Shaofeng ZHANG
. Experiment and simulation of gas-solid flow characteristics of Geldart A particles[J]. The Chinese Journal of Process Engineering, 2019
, 19(5)
: 967
-974
.
DOI: 10.12034/j.issn.1009-606X.219123
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