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An induction heating fluidized bed with liquid injection was designed to mimic the exothermic process of particles in industrial olefin polymerization fluidized beds. The effects of liquid injection flow rate on agglomeration behaviors were investigated through the characterization of agglomerate size and mass. Agglomeration mechanisms were proposed based on the experimental data of bed pressure drop, axial temperature distribution, and microscale visualization. Results have revealed that, with the increase of liquid injection flow rate, the agglomeration mechanism was controlled by the solid bridge force, the liquid bridge force, and the cooperative action of them, respectively. Wet agglomerates caused by the liquid bridge force induced local dead zones and provided a good environment for the occurrence of a hot spot and growth of solid bridge, and thus the formation of solid agglomerates. Besides, elevating the liquid injection position and increasing the induction heating power can widen the operation range of the liquid injection flow rate for fluidized bed reactors. [ABSTRACT FROM AUTHOR]

A novel induction heating apparatus is designed to mimic the exothermic process in an olefin polymerization gas-solid fluidized bed. Wax/graphite composites with core-shell structure are used as tracer particles to capture the agglomerates formed in the cold mode experiments. Pressure fluctuation sensors and image analysis methodology are used to characterize the detailed information on agglomerates such as mass, size, and compositions. Experimental results reveal that when the mass fraction of tracer particles is above 10%, agglomerates are formed in the fluidized bed. Compared with coarse particles, small particles lead to agglomeration much easier, and coalescence of small-small particles or small-coarse particles is the main mechanism by which agglomeration occurs. Analyzing the collision process of small particles and coarse particles, we conclude that collisions among small particles or collisions between small and coarse particles are more frequent and efficient than that of coarse particles. [ABSTRACT FROM AUTHOR]