Combined CFD and Monte Carlo Simulation for Modeling the Impact of Mixing on the High‐Pressure Polymerization of Ethylene

ABSTRACT The free‐radical polymerization of ethylene under high‐pressure conditions involves highly reactive radicals and short reaction times. Especially in the vicinity of the initiator feed location, mixing can influence the radical distribution and, consequently, the polymer properties. This work aims to link mixing, modeled using computational fluid dynamics (CFD), with polymer property information such as molecular weight distribution (MWD) and branching density through a Monte Carlo approach. The presented modeling framework uses the concept of compartmentalization to transfer mixing information from the CFD model to the Monte Carlo model. Comparison with polymer samples from a mini‐plant reactor shows good agreement between the simulated and measured MWDs. In contrast to most existing models based on ideal reactor concepts, the approach presented here does not require parameter adjustment, for example, for initiator efficiency. Furthermore, the developed compartmentalization model can be used as a deterministic model in place of a CFD simulation, significantly reducing simulation time.