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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]

Flow pattern of the fluidized bed is a key factor for heat transfer and the design of a new reactor. It is important to comprehend the fluidization conditions because the complex correlation between particle−particle and particle−environment in the reactor. In this study, we applied acoustic emission (AE) measurement in monitoring the particle fluidization pattern in a gas−solid bed fluidized with different sorts of particles classified by Geldart. With AE axial time average energy analysis, the flow structure of polyethylene particles was investigated both in the laboratory and plant apparatus. The results showed that the fluidization pattern in the bed is multicirculation, including the main-circulation zone, subcirculation zone, and the stagnant zone. Moreover, the influence of operating variables, such as particle size, superficial gas velocity, static bed height, and particle sorts had also been considered. It was found that the particle size, gas velocity, and particle sorts have significant impacts to the fluidization pattern. In contrast, the height of the stagnant zone did not show direct relation to the static bed height. AE measurement was proved to be reliable for understanding the dynamical features that affect the behavior of the fluidized bed. This can be useful guidance for an industrial process and help improve the process operation and the design of the new reactor. [ABSTRACT FROM AUTHOR]