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Chemical Kinetics Study Of Oil Shale Pyrolysis And Combustion

Posted on:2008-01-07Degree:MasterType:Thesis
Country:ChinaCandidate:F XuFull Text:PDF
GTID:2132360212483627Subject:Thermal Engineering
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Oil shale, as one of the important fossil fuels, has a great deal of resources. It is the important replacement of oil and natural gas. The reasonable exploitation and utilization of it has the special strategic significance to make up the deficiency of energy resource and alleviate the energy crisis. It is the foundation of oil shale optimize conversion that the pyrolysis and combustion kinetics characteristics was studied.In the paper, the pyrolysis and combustion kinetics characteristics of oil shale samples are investigated by theoretical and experimental analysis. Proximate analysis and ultimate analysis were conducted. The pyrolysis behavior of Huadian and Maoming oil shale samples was studied on the thermogravimetric analysis (TG,DTG) at different heating rates under the nitrogen environment. The apparent activation energy in pyrolysis reactions of oil shale samples has been analyzed by three kinds of iso-conversional methods. The Sestak's complex mechanism was used to fit liner for pyrolysis reaction mechanism of oil shale, and the decomposition mechanism and frequency factior were obtained. The results showed that the activation energy was not a constant throughout the reaction process, and oil shale pyrolytic mechanism was complex and mainly attributed to the nuclear mechanism. Furthermore, non-isothermal thermogravimetric combustion experiments on oil shale samples have been carried out. Two thermoanalytical methods (the Coats-Redfern method and isoconversional method) are adopted to calculate the apparent activation energy in combustion reaction of oil shale samples. The activation energy calculated by two methods showed that oil shale combustion included two phases, and the activation energy at low temperatures was lower than at high temperatures. The results analyzed by the isoconversional method showed oil shale combustion was a complex multi-step reaction process, the Coats-Redfern method assumed the reactionmechanism and it was not reasonable. In the meantime the results were discussed. Moreover, the combustion performance of oil shale and its semi-coke are studied by DSC and the effect of different heating rate has been investigated. The isoconversional method was applied to analyze oil shale kinetics characteristics. In all, the results may provide theoretical foundation for further effective exploitation and economical application of oil shale.
Keywords/Search Tags:oil shale, pyrolysis, combustion, isoconversional methods, kinetics
PDF Full Text Request
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