Influences of operating parameters on the hydrodynamics of a 3-D spout-fluid bed based on DEM modeling approach

The influences of operating parameters on the gas-solid hydrodynamics of a 3-D spout-fluid bed operated in the flow regime of Jet-In-Fluidization are numerically investigated at the particle-scale level. The gas motion and solid motion are solved under the frameworks of computational fluid dynamics and discrete element method, respectively. The dynamical property of solid phase obtained numerically is compared with the experimental data in literature. Then, the influences of the spouting velocity, the background velocity and the particle diameter on the bed hydrodynamics are discussed. The results show that vigorously lateral motion of solid phase exists in the spout-annulus interface and the vertical transportation intensity is larger than the lateral one. Increasing the spouting velocity enlarges the solid velocity but decreases its concentration in the spout and enhances the solid circulating flux of the system. Meanwhile, the enlargement of background velocity gives rise to an obvious change of voidage in the annulus. However, enlarging the particle diameter lowers the solid motion in three regions of the bed. Spout and annulus interact with each other through the spout-annulus interface. The spout boundary diverges initially, and then keeps nearly constant, finally diverges again until the bed surface. Moreover, the shape of the spouting boundary is strongly influenced by the inlet geometry. Along the bed height, this influence diminishes initially but is enhanced in the vicinity of bed surface. The enlargement of spouting velocity or background velocity leads to the expansion of the spout boundary along the bed height. In contrast, the increase of particle diameter reduces the spout boundary. (C) 2014 Elsevier B.V. All rights reserved.