MP-PIC (multi-phase particle in cell) method combined with the EMMS (energy minimization multiscale) drag force model was implemented with the open source program MFIX to simulate the gas-solid flows in CFB (circulating fluidized bed) risers. Calculated solid flux by the EMMS drag agrees well with the experimental value; while the traditional homogeneous drag over-predicts this value. EMMS drag force model can also predict the macro- and meso-scale structures. Quantitative comparison of the results by the EMMS drag force model and the experimental measurements show high accuracy of the model. The effects of the number of particles per parcel and wall conditions on the simulation results have also been investigated in the paper. This work proved that MP-PIC combined with the EMMS drag model can successfully simulate the fluidized flows in CFB risers and it serves as a candidate to realize real-time simulation of industrial processes in the future. (C) 2012 Elsevier Ltd. All rights reserved.