搅拌反应器内多层桨作用下的气泡大小分布的放大规律研究

SCALEUP CRITERIA OF BUBBLE SIZE DISTRIBUTION IN AERATED STIRRED VESSELS WITH MULTIPLE IMPELLERS

在三个体积不同的搅拌槽中,用光电毛细管探头法测定了二层桨作用条件下的气泡大小分布,结果表明:搅拌槽底层和顶层桨所对应的作用区域内的气泡大小分布之间无显著差异;搅拌槽内的气泡平均直径在几何相似,单位体积功率和表观气速均保持不变的放大过程中有增大的趋势。

A photoelectric capillary probe technique has been developed to measure the bubblesize distribution in three stirred vessels with two-stage impellers.The working fluids were air and tap water. As far as the Sauter mean diameter of bubbles and its standard variance within the impeller discharge region are concerned,experimental findings showed that no obvious difference between upper and lower impellers can be found. Regarding to the scaleup with constant power input per unit volume and same gas superficial velocity,the Sauter mean diameter of bubbles in the impeller dis- charge region seems to be unchanged,but that in the circulating region it incr- eases explieitly, d_(32R)=1.20×10^(-2)T^(0.11) (Pg/V_L)^(-0.06)W_s^(0.11) Over the operating conditions,the probability density of bubble diameter cor- responds approximately to the normal distribution and the ratio of the standard variance to Sauter mean diameter is as follows. σ_d/d_(32)=0.269T^(-0.09)