Results of experimental measurement of solids mass flux profiles in a high density circulating fluidized bed riser over a wide operating condition are described.The existence of three solids flux radial profile regimes:core-annular

parabolic and U-shaped is found.A model for all the three regimes is proposed and correlations of model parameters are obtained.Comparison of predicted solids flux profiles with experimental data is very promising.The correlations for the boundaries of the three regimes and the radius of core for core-annular regime are obtained.