Model-based analysis of the impact of the distributor on the hydrodynamic performance of industrial polydisperse gas phase fluidized bed polymerization reactors

• Effect of perforated distributor on fluidization structure was studied in industrial FBR.
• Perforated distributor was predicted dead zone formation near the corners of distributor.
• Decreasing the cluster formation, bigger bubble size and more heterogeneous fluidization structure was predicted in perforated distributor case.

A two dimensionally Eulerian–Eulerian multiphase flow model coupled with a population balance modeling (CFD–PBM) simulation was implemented to investigate the fluidization structure in an industrial scale gas phase polymerization reactor (FBR). Direct quadrature method of moments (DQMOM) was employed in this model to solve the PBM. Two cases including perforated distributor and complete sparger have been applied to examine the flow structure through the bed. A simulation of the reactor with perforated distributor was performed first to validate and evaluate the impact of distributor's characteristics on the fluidization behaviors. The predicted results were in good agreement with the industrial data in terms of pressure drop and bed height. The results showed that different heterogeneous flow patterns were created in a perforated distributor, due to more kinetic energy and jet formation above the distributor. A dead zone is expected to be formed near the corners of the perforated distributor. In addition, the cluster formation is expected to be decreased in comparison with the complete sparger plate distributor. Furthermore, the results predicted bigger bubble diameter in the case of the perforated distributor by using an image processing technique. The information obtained from this study could be important to assure efficient industrial operations of FBRs.

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