A comprehensive study of hydrodynamic behavior including the particle mass flow rate, solid volume fraction and particle velocity, as well as the mixing behavior, was conducted in the pre-lifting scheme with a central tube and the scheme without a central tube. Compared with the pre-lifting scheme without a central tube, higher mass flow rate, more uniform flow structure, and more vigorous gas-solid contact behaviors were obtained in the riser entrance region of the pre-lifting scheme with a central tube. The suggested installation height for the feed-stock nozzles was lower in the pre-lifting scheme with a central tube as determined by analyzing the radial non uniformity index of catalyst particles distributions. However, relatively complete and desirable mixing of cold and hot particles was presented in the pre-lifting scheme without a central tube by analysis of the distributions of heat exchange uniformity. Finally, the key hydrodynamic and mixing features were summarized, and some optimized structures over the pre-lifting scheme with a central tube were proposed to improve the mixing of cold and hot particles. (C) 2016 Elsevier B.V. All rights reserved.