A CFD-PBM-PMLM Integrated Model for the Gas-Solid Flow Fields in Fluidized Bed Polymerization Reactors

摘要

Although the use of computational fluid dynamics (CFD) model coupled with population balance (CFD-PBM) is becoming a common approach for simulating gas-solid flows in polydisperse fluidized bed polymerization reactors, a number of issues still remain. One major issue is the absence of modeling the growth of a single polymeric particle. In this work a polymeric multilayer model (PMLM) was applied to describe the growth of a single particle under the intraparticle transfer limitations. The PMLM was solved together with a PBM (i.e. PBM-PMLM) to predict the dynamic evolution of particle size distribution (PSD). In addition, a CFD model based on the Eulerian-Eulerian two-fluid model, coupled with PBM-PMLM (CFD-PBM-PMLM), has been implemented to describe the gas-solid flow field in fluidized bed polymerization reactors. The CFD-PBM-PMLM model has been validated by comparing simulation results with some classical experimental data. Five cases including fluid dynamics coupled purely continuous PSD, pure particle growth, pure particle aggregation, pure particle breakage, and flow dynamics coupled with all the above factors were carried out to examine the model. The results showed that the CFD-PBM-PMLM model describes well the behavior of the gas-solid flow fields in polydisperse fluidized bed polymerization reactors. The results also showed that the intraparticle mass transfer limitation is an important factor in affecting the reactor flow fields.