Study On The Density Control Mechanism Of The Binary Medium Solid Fluidized Bed

The air dense medium fluidized bed could deal with grade size of-50+6 mm coal efficient.However,the traditional air dense medium fluidized bed(CFB)can only form a single and high separation density by using a single addition of heavy elements(except for the self forming medium).In order to reduce the density of the bed separation,effective separation of the materials,low density and high density quartz sand as magnetite powder mixed with heavy give into the air dense medium fluidized bed,the bed layer of lower density,lower density,particle size separation of solid fluidized bed expanding gas,provide a theoretical basis for the effective separation of low density coal the.The particle size of quartz sand was 0.25-0.35 mm,and the particle size of magnetite powder was 0.15-0.2 mm.Choose two kinds of medium particle size distribution is narrow particle size,not only considering the density differences of quartz sand particles with magnetite particles,also considering the whole bed layer to form a relatively stable low density separation medium layer,which is not only a separation for low density coal particles,more conducive to prevent the high density of coal particles mismatch,layered accelerate each density of coal particles,improved gas solid fluidized bed separation effect.The evaluation of fluidized bed mass is considered from two aspects.Firstly,the distribution of bed density,including the spatial distribution of bed density along the bed height and the radial direction of the bed surface.Secondly,the density of the bed density is uniform,the density of the bed is calculated as the sample density,and the uniformity of the bed density is represented by the sample standard deviation.The experimental results show that the density distribution of the two component mixing and heavy bed is different from that of the quartz sand,the fluidization number and the static bed height.When the content of quartz sand is 5%-20%,when the flow number N=1.0-1.3,the bed density overall uneven distribution,large fluctuations.When the content of quartz sand is greater than 25%,the bed density decreases gradually along the vertical direction.The variation rule of the standard deviation of the density distribution of different composition and heavy bed density is not the same.When the content of quartz sand and heavy low(?=5%-15%),the standard deviation of bed density decreases with the increase of fluidization number;when the content of quartz sand with heavy increasing(?=20%-30%),bed axial or radial density standard deviation is large,the bed gas velocity,bed density fluctuation big bed,poor stability,in order to make the bed density distribution,scope control test flow number N=1.4-1.6.According to the calculation of bed density formula of theoretical derivation,determination of related parameters,the mathematical relation of two mixed heavy medium fluidized bed density and quartz sand content,fluidization of fluidized bed,the density model,and compared with the measured values,to test its applicability.In the experiment,the selected-13+6 mm medium grade ash grade coking coal was selected as the research object.The results show that the separation of the raw coal is 0.085 g/cm~3.When using a single heavy medium separation,separation of coal ash high income two yuan;when using mixed with heavy separation,with the increase of quartz sand content,the bed separated from coal ash products showed a trend of gradual decrease,coal ash can be as low as 8.76%.