粉体搅拌扭矩的试验及关联式

在直径为480mm的平底搅拌槽内，采用平均直径为4.89μm的氢氧化铝粉体进行搅拌扭矩的试验。通过扭矩传感器测量3种不同型式（开启涡轮XCK、二叶直桨PJ和管形桨GXJ）的6个搅拌器（XCK348、XCK290、PJ348、PJ232、GXJ348和GXJ232）的扭矩。试验结果表明：针对不同的搅拌器型式，搅拌器的扭矩增加幅度从高到低的排序是XCK348＞GXJ348＞PJ348＞XCK290。随着粉体高度的增加，GXJ348搅动效果相对较好。相同工况下搅拌的扭矩随着转速增加而有所下降。搅拌的扭矩大小主要是和搅拌器离粉体表面的高度和搅拌的Froude数有关。对于搅拌器组合，当间距较大时各层搅拌器互相不影响；当层间距与搅拌器直径之比小于0.32时，各层搅拌器存在相互作用。通过扭矩的量纲分析和搅拌粉体的受力分析，分别获得了3种搅拌器型式的扭矩关联式。

Determination and correlation of torque for powder stirring

Aluminum hydroxide powder with average diameter of 4.89μm was used to carry out the experimental determination of torque in a flat-bottomed stirred tank with diameter of 480mm. Torque sensor was used to measure the torque of three different impellers (pitched-blade turbine XCK, two-blade paddle PJ and tube-shaped impeller GXJ) including six impellers (XCK348, XCK290, PJ348, PJ232, GXJ348 and GXJ232). The experimental results showed that the torque of the impeller increases with the height of the powder. The order of the increasing torque of the impeller from high to low is XCK348>GXJ348>PJ348>XCK290. With the increase of powder height, the GXJ348 impeller has better agitation performance compared to other impellers. As the agitation speed increases, the impeller torque decreases. The impeller torque is mainly related to the height of the impeller from the surface of the powder and the impeller Froude number. For impeller combinations, when the layer distance is large, the impellers do not affect each other. When the ratio of the layer distance to the impeller diameter is less than 0.32, the impellers affect each other. Through the dimensional analysis of torque and the force analysis of stirring powder, two torque correlations for the three types of impellers were obtained.