Three-dimensional numerical simulation of gas-solid flow behavior in spout-fluid bed

Numerical simulation of gas-solid flow behaviors in a spout-fluid bed coal gasifier was carried out three dimensionally by discrete element method (DEM). Eulerian method and Lagrangian method were employed to deal with the gas phase and solid phase respectively. Shear lift force, Magnus lift force as well as drag force, contract force and gravitational force acting on individual particle were considered when establishing the mathematic models. The collision of particles was modeled by soft-sphere model. The flow patterns, forces acting on particles, particle mean velocities, gas turbulent intensities and particle turbulent intensities under the typical operating conditions were obtained. The results show that the ratio of collision between particles increases with the increase of spouting gas velocity but decreases with the increase of particle size, while the ratio of collision between particles and wall is found no variation with spouting gas velocity and particle size. Gravitational force, drag force and contact force dominate the particle motion, while shear lift force and Magnus lift acting on the particles are negligible when the particles are not in the boundary of the spout region. The gas turbulent intensity is always two or three times stronger than the particle turbulent intensity, while they are both smaller near the wall.