错位Rushton桨气液分散特性和传质性能实验研究

Experimental study on gas-liquid dispersion and mass transfer of dislocated-blade Rushton impeller

为了强化标准Rushton桨的气液搅拌性能,设计错位Rushton桨.通过气液搅拌实验,分析不同搅拌转速和通气流量条件下,两种搅拌桨的气液分散特性、传质性能和通气搅拌功率.采用流场可视化技术,观察搅拌槽内气泡分布状态.利用图像处理技术获取气泡尺寸,使用亚硫酸盐氧化法测试气液间氧体积传质系数.研究结果表明,与标准桨相比,错位桨轴向搅拌范围大,搅拌槽内的气泡分布均匀,气泡尺寸较小.在一定操作范围内,使用错位桨可以有效地提高气液传质速率,加快气体溶解速度.在相同的操作条件下,错位桨搅拌功率略低,通气后的功率下降幅度稍小,载气性能强,更适用于气液搅拌操作.

The dislocated-blade Rushton impeller was designed in order to strengthen the performance of gas-liquid mixing of the standard Rushton paddle.The gas-liquid dispersion characteristics,mass transfer properties and gassed power consumption of those two impellers were investigated by gas-liquid stirring experiment under the condition of different stirring speed and air-flow rates.Bubble dispersion state in the stirring tank was observed by using visualization technology.The bubble diameter was obtained by the image processing method.The sodium sulfite test method was used to calculate the oxygen volumetric mass transfer coefficient.Results indicate that compared with the standard Rushton impeller,the areas in the axial direction influenced by the dislocated-blade Rushton impeller are broader,the bubble distribution in the stirring tank is more uniform and the bubble diameter is apparently smaller.In the certain range of control condition,the rates of mass transfer and gas dissolving are effectively improved by using the dislocated-blade impeller.At the same conditions,the power consumption and the aerated power drop after gassing of the dislocated-blade impeller are small.The performance of the carrier gas ability of the dislocatedblade impeller is strong,so it is more suitable to be applied to the gas-liquid stirring operation.