空气重介质流化床中细粒煤的流化与分选特性

3~1 mm粒级细粒煤介于煤粉与传统空气重介质流化床分选所适用的粒度之间，其在空气重介质流化床中被分选的同时对自身分选与流化特性产生重要影响。利用高速动态摄影等手段详细研究了空气重介质流化床分选3~1 mm细粒煤过程中不同流化数下床层的流化特性、压降波动、煤粒分离混合规律以及流化床中不同高度处的密度分布，阐释了气泡在分选过程中的作用机理。结果表明,加入一定量细粒煤后床层密度降低，流化效果发生了一定程度的改变。随着气速的增加，煤粒在流化床中先后经历了分离与混合两种状态，流化床各高度的密度也随之改变。当流化数在1.8~2.0时煤粒达到较好的分离效果。随着气速增大煤粒受气流影响增大，不再严格按照流化床密度分离。

Bed fluidization characteristics and separating effect of fine coal in an air dense medium fluidized bed

Fine coal (3-1 mm) is between pulverized coal and particles that is suitable for traditional air dense medium fluidized bed.The addition of fine coal can thus affect bed fluidization and separation characteristics.To elucidate the bubble-driven mechanism,the fluidization characteristics,pressure fluctuation,separation/mixing efficiency of fine coal and fluidized bed density at different heights were investigated by varying number in an air dense medium fluidized bed using high-speed dynamic camera.Results show that bed density decreases while fluidization quality changed slightly with the addition of fine coal.With the increase of gas velocity,coal particles separate initially,then change into mixed state.Meanwhile,bed density changes at different heights.When fluidization number is in the range of 1.8 to 2.0,coal particles achieve a maximum separation efficiency.However,with the gas velocity further increases,the influence of air flow increases,and coal particles could not be separated according to fluidized bed density strictly.