无挡板搅拌槽的固液悬浮特性

采用PC-6D浓度测量仪研究了无挡板Rushton桨搅拌槽内石英砂-水两相体系的固液悬浮过程,测量了不同桨叶安装高度和桨径比时的临界悬浮转速,分析了桨叶安装高度、桨径比以及搅拌转速对固相浓度分布和功率消耗的影响。结果表明,无挡板时的临界悬浮转速和功率准数比有挡板时小,且随桨叶安装高度的增大而增大,随桨径比的增大而减小;对于无挡板固液悬浮,C=T/5、D=T/3时的悬浮性能最好,增大桨径比和搅拌转速均不能明显改善固液悬浮效果。

Solid-liquid Suspension in an Unbaffled Stirred Tank

The silica sand-water two-phase suspension in an unbaffled stirred tank agitated by a standard Rushton turbine was experimentally studied using the PC-6D particle concentration measuring instrument.The critical suspension speeds under different impeller off-bottom clearance and impeller-to-tank diameter ratios were measured and compared with those in the baffled stirred tank.The solids concentration and power profiles under different operating conditions were analyzed.Results showed that the critical suspension speed and power number for the unbaffled stirred tank are smaller than those in the baffled stirred tank.Both of them were found to increase with increase of the off-bottom clearance and decrease with increase of the impeller size at constant tank diameter.For the unbaffled suspension operation,the suspension is the best with impeller off-bottom clearance C=T/5 、and impeller-to-tank diameter ratio D=T/3.There is no help to improve the suspension uniformity by increasing the impeller-to-tank diameter ratio or the impeller rotational speed.