Real-time inferencing of solid–liquid phase equilibria in solution polymerization of polyethylene

An algorithm for the real-time prediction of multi-component solid–liquid equilibrium (SLE) in a polyethylene (PE) process flowsheet has been attempted. While most of the available literature assumes the polymer to possess a single average molecular weight and lump the entire polymer as a single component, the present work proposes to consider a polydispersed multi-component fraction, characterized by the pseudo-component approach. The SLE model has been used to study the effects of monomer and polymer polydispersity in solution polymerization process. At first, it has been validated on the solubility data of n-alkanes in n-hexane, polyethylene in M-xylene and on wax precipitation from a mixture of n-paraffins. The SLE model is based on perturbed chain SAFT (PC–SAFT) equation of state (EOS). An algorithm for the real-time prediction of SLE phase boundaries in solution polymerization has been subsequently presented. A simulation experiment on the polyethylene flowsheet highlighted the potential of real-time inferencing for industrial applications.