用落球法研究气固浓相流化床表观粘度

Research on Apparent Viscosity Characteristics of Gas-Solid Dense Phase Fluidized Bed with Falling Spheres Method

用落球法对不同参数条件下的气固浓相流化床床层表观粘度进行测量和线性拟合,得到了流化床的床层屈服应力和塑性粘度与各因素的关系;研究了粘度对分选时间的影响,建立了振动流化床分选时间与表观粘度和物料密度之间的数学模型.结果表明,在同一气速下,随石英砂颗粒粒级及床层高度增大,床层表观粘度整体增大.在一定的流化气速范围内,石英砂介质粒级为0.25～0.125 mm、床高190 mm时,床层粘度稳定在0.39～0.51 Pa?s.加入振动后,床层粘度明显下降,频率15 Hz、振幅1 mm时流化效果较好,床层粘度稳定在0.69～0.95 Pa?s.

Based on falling spheres method the apparent viscosity in gas-solid dense phase fluidized bed was measured under different parameters.The relationships of yield stress and plastic viscosity of fluidized bed layer with influential factors were correlated.The effect of viscosity on separation time was studied,and the mathematical model on the relationship of separation time with the apparent viscosity and the density of fluidized material in the vibration fluidized bed developed.The results showed that under the same gas velocity,with the increase of quartz sand grain size and bed height,the apparent viscosity increased totally.Within a certain range of the fluidizing gas velocity,the apparent viscosity was 0.39～0.51 Pa·s when the quartz sand size was 0.25～0.125 mm and the bed height 190 mm.After the exertion of vibration,the bed layer viscosity decreased obviously,and good effect of fluidization occurred under 15 Hz frequency and 1 mm amplitude.The apparent viscosity was stable at 0.39～0.51 Pa·s.