Pyrolysis characteristics of oil-field sludge and the comparison of kinetic analysis with two representative methods

• Published in: Journal of petroleum science & engineering 2019-11, Vol.182, p.106309, Article 106309
• Main Authors: Miao, Wenjuan, Li, Xiangguo, Wang, Yingbin, Lv, Yang
• Format: Article
• Language: English
• Subjects: Coast-Redfern method; Flynn–Wall–Ozawa method; Oil-field sludge; Pyrolysis kinetics
• ISSN: 0920-4105; 1873-4715
• DOI: 10.1016/j.petrol.2019.106309

The pyrolysis of oil-field sludge (OS) has the appeal of resource recovery for this kind of waste disposal. In this paper, we investigate the pyrolysis kinetics of OS with Coast-Redfern (CR) and Flynn-Wall-Ozawa (FWO) methods in a wide temperature range (305–1223 K). The pyrolysis process of OS mainly includes light organics vaporization (Stage-2), middle and heavy organics and carbonates decomposition (Stage-3), coke reduction and other inorganics decomposition (Stage-4). The kinetic analysis manifests that Stage-2 meets well with the reaction order mechanism, and the reaction order (n) is 2 and in the range of 1.3–1.9 obtained by CR and FWO, respectively. The divergence of the two methods mainly appears in Stage-3, where Ea calculated by FWO method is much higher than that by CR method. CR method gives D1 model for this stage, while FWO method picks D3 model to describe this stage. The simulation plots indicate that the results of CR method are more credible. As for Stage-4, both methods select G(α) = α as the mechanism, but CR method performs better agreement and a smaller discrepancy than FWO method does. Thus, FWO method is considered less accurate for OS analysis. •Ea by CR is 84.83 kJ mol−1, 95.52 kJ mol−1 and 306.38 kJ mol−1 for Stage-2 to 4.•Ea by FWO is 72.09 kJ mol−1, 245.74 kJ mol−1 and 454.03 kJ mol−1 for Stage-2 to 4.•Reaction order (n) is 2 and 1.3–1.9 obtained by CR and FWO.•CR and FWO respectively select D1 and D3 model to simulate Stage-3.•Both methods describe Stage-4 with the mechanism of G(α) = α.