Research On Fluidization And Separation Characteristics Of A Gas-solids Agitated Fluidizedbed

Gas-solids agitated fluidized bed is a new type of fluidized bed which make the bed fluidization under the agitating force.This innovation has employed agitation to the fluidized bed which can significantly reduce channeling, shortcircuits and bubble size inside the separation bed to increase the bed stability, therefore, materials that difficult to fluidize under regular circumstance can be fluidized.Compared with coarse grained coal dry separation technology, fine coal dry separation technology hasn’tmature solution. All in all, it is of vital importance to study the application of pulsed fluidized bed for fine coal beneficiation.The thesis conducted related research for application focused on agitation speed’s influence on fluid and separation characteristic during the dynamic separation adopting a combination of experiment and numerical calculation method. It built up the regression model of relation between critical fluidization velocity and agitation speed. The analysis of bed density distribution in different agitation speed condition demonstrated that the variance of bed density fluctuation in axial reduces to 0.06 under the agitation speed of 50 r/min to 75 r/min, shows that agitation field has a certain positive effect on the stability of fluid bed. However, the back mixing of medium solids will become more intensive under agitation speed condition that beyond this scope, especially when it reaches 100 r/min, with which separation will be affected significantly by the poor fluidization situation.Bed wall bubble behavior at different agitation speedwas investigated with high-speed dynamic video camera and the growth curvewas plotted. The comparison of growth curve at different agitation speed indicated that agitation speed affect obviously on particle’s growth process.bed wall bubble’s growth velocity decreases and the average bubble size reduces significantly with the rising of agitation speed. This trend of change manifested that rising agitation speed improves the ability of particle to retain aeration in fluidized bed and plays a role of aid flow to some extent.-6+3 mm fine coal separation experiment was carried out in order to study agitation speed and Fluidization velocity’s effect on separation.The result showed that agitation speed obviously affects the practical separation.in thebest conditions,tailing ash is 12.26%(raw coal is 25.09%), yield is 70.13%, the biggest drop ash is 12.83%,the best value of the E is 0.135 g/cm3,obviously better than normal fluidized bed 0.215 g/cm3.