双层桨自吸式气液搅拌釜内的功率准数

Power number in a self-inspirating gas-liquid stirred tank with dual impellers

对双层桨自吸式搅拌釜的功率准数进行了研究,考察了不同搅拌条件对功率准数的影响。实验结果表明,随搅拌转速的增加,功率准数先减小后增大然后又减小。功率准数随介质黏度和密度的增大而增大。适宜的桨叶组合为抛物线型桨+六叶上斜叶桨,该组合的搅拌混合效果最好,功率准数较小。随桨叶间距的增大,功率准数增大;当下层桨叶角度为30°,桨叶系数为0.125时,泵送效率最高,气含率最大,功率准数最小。当气体实现自吸分散后,功率准数与雷诺数(Re)的关系为N_p∝Re^(-0.84),随着雷诺数的增加,功率准数大幅降低。

Power number(Np)in a self-inspirating stirred tank with dual impellers was studied.The effect of stirring conditions on Np was investigated.The results showed that with the increase of the stirred speed,Np increases after decreasing,and then decreases again when reaching the critical speed.Np increases with the increases of the medium viscosity and density.The mixing effect of parabola turbine+six pitched blades upflow turbine combination is the best,and Np is minimal.When the impeller spacing increases,the pumping effectiveness of the lower impeller decreases,and Np increases.When the angle of the lower impeller is 30°and lower impeller coefficient is 0.125,the rate of gas induction is maximum,and Np is minimal.When the gas gets self-inspirating dispersion,the relationship between Np and Reynolds number(Re)is Np∝Re-0.84,at this time,the Np decreases greatly with the increase of Re.