Research On The Mechanism Of Two-Phase Distribution And Density Regulation Of Separating Gas-solid Fluidized Bed

Coal is the major energy resource in the world,which plays the driving role in global economic development and social improvement.The beneficiation process is the basic indemnificiation of the efficient utilization and sustainable development of coal resourcs.The dry fluidized separation technology is the indispensable and important part of coal beneficiation field,which provides an effective way for the coal separation and utilization in drought and frozen area.At present,the research on the fundamental theory of dry fluidized separation is still inadequate.Especially,the mechanism of interaction between fluidization characteristics and coal separation performance is unclear,and also lack of efficient and reliable dry fluidized separation regulation method.These problems restrict the industrial application of dry coal fluidized separation.In consideration of these above problems,the fundamental study of fluidization characterists and dry coal beneficiation of gas-solid fluidized bed was conducted in this study.Through the analysis of incipient fluidization behavior of gas-solid fluidized bed,with the considering the bed pressure effects,the incipient fluidization state equation is proposed for gas-solid fluidized bed,and the corresponding minimum fluidization velocity equation is also established.The gas-solid fluidization behavior of Geldart group B powders is explored,and the correlation parameter of two-phase theory of fluidization for Geldart group B powders is derived.Furthermore,the two-phase theory of fluidization has been modified,and the gas distribution pattern in the gas-solid fluidized bed is revealed,which provides the basis for the theoretical calculation of dry fluidized separation processing.Based on the gas-solid fluidization behavior,with the considering of modified two-phase theory of fluidization,the spatial density model of gas-solid fluidized bed is established,which reveal the mechanism of influencing factors of gas-solid fluidized bed density.The spatial density model is used to explain the relatively low density in the gas-solid fluidized bed,and binary mixtures can be utilized to improve the bed density distribution and enhance the uniformity and stability of fluidized bed density,to acheave a high efficiency dry coal fluidized beneficiation.According to the force analysis of feed material in the gas-solid fluidized bed,the separation density predicting model of fluidized bed is established,which expound the influencing factors and the disturbance mechanism of dry fluidized beneficiation method.This model reveals the correlation mechanism between the fluidization characteristics and coal separation behavior,and ensures the boundary conditions of the lower limition of dry fluidized separation,as well as the determining method,which provides the theoretical foundation of high-efficiency dry fluidized separation processing.The semi-industrial dry fluidized separation system is used to upgrade the raw coal from Shanxi Lu'an mine,Inner Mongolia Lijiahao mine,Shanxi Hecaogou mine and Jiangsu Jiahe mine.Based on the abovementioned control mechanism of dry fluidized beneficiation method,the separation conditions are optimized for different types of raw coals.The experimental results show that the separation efficiency of-50+25 mm?-25+13 mm and-13+6 mm coarse coal is near 0.03 g/cm~3?0.07 g/cm~3and 0.10 g/cm~3,respectively.The corresponding separation density increases with the decreasing of feed coal size,and the separation density prediction is very close to the experimental measurement,with the Pearson correlation coefficient of 0.95.In addition,the literature experimental data of dry fluidized separation process are summarized to verify the separation density predicting model,and the results show that the model prediction is in agreement to the experiments,with Pearson correlation coefficient is0.98.In conclusion,the separation adjustment mechanism which proposed in this study has high accuracy and reliability properties,as well as the wide applicability.