Simulation and study of the flow field in a kettle-type reactor for ethylene polymerization

Abstract Addressing the complexities inherent in the polymerization process for solution method polyethylene production, particularly the challenges in describing the turbulent three-dimensional flow field within the reactor and the precise design of reactor structural parameters, this research leverages computational fluid dynamics (CFD) methods integrated with polymerization reaction kinetics equations. We have formulated User-Defined Functions (UDFs) for a quantitative representation of the polymerization process. Employing the Realizable k-epsilon turbulence model and Sliding Grid (SG) technique, we analyzed the flow dynamics and field distribution within the reactor, elucidating the distribution patterns of temperature, pressure, and concentration fields. A comparative assessment of simulation outcomes against experimental data revealed that the average deviation of the simulated temperature field from actual operating conditions falls within the permissible error range, thereby affirming the simulation model’s validity. Utilizing local sensitivity analysis, we investigated the impact of impeller structural parameters on mixing time and stirring power. Our analysis of the most sensitive structural parameters indicated that impeller diameter and the number of impellers are pivotal in reducing mixing time and stirring power, respectively. Notably, the stirring power escalates with an increase in the number of impellers, while the mixing time exhibits a trend of initial decrease followed by an increase with varying impeller diameters. The methodologies and patterns discerned in this study provide insightful design references for the design and optimization of reactors across different tonnages.