Properties, combustion behavior, and kinetic triplets of coke produced by low-temperature oxidation and pyrolysis: Implications for heavy oil in-situ combustion

This work aimed at investigating the crucial factor in building and maintaining the combustion front during in-situ combustion (ISC), oxidized coke and pyrolyzed coke. The surface morphologies, elemental contents, and non-isothermal mass losses of the oxidized and pyrolyzed cokes were thoroughly exam-ined. The results indicated that the oxidized coke could be combusted at a lower temperature compared to the pyrolyzed coke due primarily to their differences in the molecular polarity and microstructure. Kinetic triplets of coke combustion were determined using iso-conversional models and one advanced integral master plots method. The activation energy values of the oxidized and pyrolyzed cokes varied in the range of 130-153 kJ/mol and 95-120 kJ/mol, respectively. The most appropriate reaction model of combustion of the oxidized and pyrolyzed cokes followed three-dimensional diffusion model (D-3) and random nucleation and subsequent growth model (F-1), respectively. These observations assisted in building the numerical model of these two types of cokes to simulate the ISC process. (C) 2021 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.