Experimental Research On Fragmentation And Attrition Characteristic Of Oil Shale In Fluidized Bed

Oil shale is a kind of potential energy and its reserves is tremendous. The development and utilization of oil shale have a history of nearly 200 years. Because oil shale contains high organic contents, it usually can be used by refining shale oil. If unreasonable processing semi-coke and small particle oil shale of refines oil, the huge pollution to the environment will be caused.Thermal fragmentation characteristic of oil shale and semi-coke is preliminarily determined in a bench-scale CFB combustor. The test is compared by Huolinhe lignite. The influence of a variety of factors such as the particle diameter,the temperature,the combustion time and the fluidizing velocity on fragmentation index of oil shale and semi-coke are studied. The fragmentation index increases with increasing particle size, bed temperature,residence time and fluidizing velocity. The fragmentation indexes of semi-cokes are higher than oil shale's under the same condition. Different restoring temperatures of oil shale have various degree of fragmentation that is increasing with higher restoring temperature. By contract,the fragmentation index of Houlinhe lignite is the highest in all samples. The extent of influence of operational parameters on fragmentation was studied by gray relational analysis method. It is indicated that oil shale,400℃and 500℃semi-coke had the same sequence of influence as follows: bed temperature had the greatest influence,the particle diameter took second place,the combustion time was least. But the 600℃semi-coke had slightly difference: The degree of influence of fluidizing velocity was higher than the particle diameter's.The influence of various factors was investigated, such as the bed temperature, fluidizing velocity and fluidizing time on weight remaining and changing radio of particle diameter. The experimental attrition rate constants obtained from the second-order attrition model are used to fit a modified Arrhenius equation, with an activation energy for the shale ash of 1.072KJ/mol and the frequency of 5.5074×10-7m/s2·g. Correlation of bed material weighting including time, bed temperature and fluidizing velocity was obtained. The predicted points are in good agreement with the experimental data.