Detailed Multiphase Chemical Kinetic Model for Polymer Fouling in a Distillation Column

Polymer fouling is a ubiquitous but unsolved problem in the separation train downstream of a steam cracker. A mechanistic understanding of polymer fouling would guide mitigation. We present a multiphase chemical kinetic model to predict the polymer film growth rate in an industrial “debutanizer” distillation column. Modeling innovations are introduced, which allow us to construct models including thousands of chemical reactions occurring in the liquid and film phases, vapor–liquid equilibria of hundreds of species, transport between the phases, and flows between the trays. All of these significantly affect the fouling rate. Most of the critical model parameters are derived from quantum chemistry calculations. The modeling method is validated using experimental film growth measurements made with a quartz-crystal microbalance. The debutanizer fouling model clarifies the mechanistic details of the fouling process. Challenges in more accurately predicting polymer fouling in industrial units are discussed.