Discrete particle simulation of spouted bed with heat transfer

Abstract

The aerodynamics of particles and gas flow in a two-dimensional spouted bed (2DSB) with draft is investigated with the aid of the Discrete Element Method (DEM). The geometry of the 2DSB with draft plates is set as close as possible to the experimental apparata of Kudra (1992) and Kalwar (1991). The physical properties of the coarse pareticles are similar to those of shelled corn. The calculated minimum spouting velocity and pressure drop agrees well with the correlations of Kudra (1992) and Kalwar (1991). In the spout region, the particle vertical velocities are found to decrease as the height increases. The fluid velocity in the downcomer region decreases as the superficial gas velocity increases. The particle circulation rate increases when the friction coefficient decreases or the separation height increases. At the minimum spouting velocity, the bed height does not affect the particle circulation rate in the 2DSB with draft plates. The draft plates not only reduce the minimum spouting velocity and pressure drop but also a increases the maximum spoutable bed height. The effect of taking out the draft plates on the spouting phenomenon is investigated and the effect of putting in a deflector on the possible breakage of the particles are also estimated. The gas-to-particle heat transfer in 2DSB with draft plates is also investigated with aid of the DEM and the developed thermal model. It is found that the gas-to-particle heat transfer occurs mainly in the central or spout region of the bed as the reported by Freitas and Freire (1998).