Study On The Combustion Mechanism And Kinetic Model Of Oil Shale

More and more countries have increasingly attached on the exploitation and utilization of oil shale with the increasingly rigorous situation of energy resources nowadays. The study on combustion characteristics of oil shale is the foundation and key factor for its development and comprehensive utilization.The devolatilization characteristics of Wangqing oil shale were studied in a laboratory scale fluidized bed. The characteristic of furnace temperature variation, preheating time of particle, ignition, and burnout were studied in detail during combustion process of oil shale. The effect of batch mass, bed temperature, fluidization velocity, and moisture content on volatile combustion was also investigated. The experimental results show that the volatile combustion time was in accordance with empirical model and the volatile combustion time was mostly influenced by the bed temperature and reaction mechanism. A new modified model for volatile combustion time related to temperature, particle size, and reaction mechanisms was proposed. The calculated results with this model are in agreement with the experimental data, and it can be used to predict the volatile combustion time for the high temperature region.The TGA curves for oil shale combustion were simulated by Weibull Distribution. The combustion kinetics was analyzed by sigmoidal model and it has shown that the Weibull Distribution could describe weight loss of combustion for oil shale well. The parameters of Weibull and kinetics that characterized oil shale combustion presented some certain rules for the large amounts of volatile matter contents.The distributed activation energy model that characterized kinetics characteristics was also analyzed and the Weibull Distribution was applied for the solution of nonisothermal kinetics. A method with grid-search algorithms for the solution of kinetic parameters of oil shale was proposed. Some kinetic parameters were obtained and the results showed that the algorithms proposed could describe the behavior of weight loss well during combustion process for oil shale in mathematical meanings.