Kinetics of Cracking and Devolatilization during Coking of Athabasca Residues

Abstract

The kinetics of cracking, coking, and devolatilization of Athabasca bitumen were investigated by reacting thin films of feed material. Samples of vacuum residue (524 °C+), scrubber bottoms, and residue from a batch fluid coker were reacted in films of thickness 20 μm on strips of Curie-point alloy. The strips were heated to temperatures of 457, 503, and 530 °C in a nitrogen atmosphere using an induction furnace. After reaction, the remaining unconverted liquid was extracted from the films, the toluene-insoluble residue was weighed, and the condensed vapor and extract liquids were analyzed for microcarbon residue content (MCR) and boiling distribution by simulated distillation. The kinetics of reaction and devolatilization were consistent with a lumped kinetic model that included cracking, coke formation, and vaporization limited by equilibrium ratios and mass transfer. The kinetic model was able to reproduce the experimental data for total extractable and coke yield as a function of time, as well as the y...