Thermal Fouling: Heat-Induced Deposition and Coking

Abstract

Heat induced deposition and pyrolytic coke formation phenomena are described using the dispersed particle solution model of petroleum residua. Below pyrolysis temperatures, heat induced deposition appears to be reversiblewith solvation shell energies ranging from about 0.5-1.8 kcal/mol. At pyrolysis temperatures, the protective shell surrounding asphaltene cores is irreversibly destroyed. Coking Indexes were developed to monitor proximity to coke formation during the pyrolysis induction period. Once coke formation begins, the initial amount formed is related to the original residuum free solvent volume. Coke formation was modeled using zero order kinetics as a two stage process. Activation energies for the first stage ranged from 22-38 kcal/mol, and activation energies for the second stage ranged from 54-83 kcal/mol.