Hydrodynamic simulation of gas-solid flow in a riser using kinetic theory of granular flow

The dynamic behavior of gas-solids flow in a 6-m high riser was predicted using a transient two-dimensional (2D)hydrodynamic model based on the kinetic theory of granular flows. Instantaneous and local gas-particle velocity, void fraction and turbulent parameters were obtained. Predicted time-averaged particle concentrations and velocities reflect the classical core-annular flow structure in agreement with experimental measurements, in particular, with those reported by Miller and Gidaspow [AIChE J. 38 (1992) 1801]. Predicted instantaneous solids concentration frequencies compared well with the experimental data for various regions of the riser. Computed total granular temperature distributions in the riser qualitatively agree with experimental data. High thermal conductivities of fluidized powders (about 50 times that of the fluidizing gas) were estimated from the kinetic theory without adjusted parameters. Effects of initial conditions, inlet geometry. riser diameter and riser vertical inclination were assessed. Unexpected strong distortions of solids concentrations and vertical fluxes were predicted for small inclination angles of the order of 2degrees. Analysis of experimental data should, therefore, be carefully conducted to ensure that riser inclination is not too important over the length of the riser in order to eliminate potential artifacts due to this geometric parameter. (C) 2003 Elsevier Science B.V. All rights reserved.