水流速度对微孔曝气充氧能力的影响机制研究

Research on the Influence Mechanism of Water Flow Velocity on the oxygenation Capacity of Microporous aeration

以标准氧总转移系数(KLa20)为评价指标,研究了不同通气量下水流流速对刚玉微孔曝气器清水充氧性能的影响,从气泡Sauter平均直径、液相气含率及流体力学角度分析了断面流速对刚玉微孔曝气器充氧能力的影响机制结果表明,通气量一定时,刚玉微孔曝气器的KLa20随断面流速的增加而增大;随着通气量的增加,刚玉微孔曝气器的KLa20随断面流速增加而提高的幅度逐渐减小;随断面流速提高,气泡Sauter平均直径逐渐减小,液相气含率逐渐增加;构建的清水推流条件下刚玉微孔曝气器KLa预测模型的预测结果与实测结果具有较高的吻合度,其中弗劳德数是对刚玉微孔曝气器KLa影响较大的参数。研究结果对实际污水处理曝气系统的工程设计具有一定的指导与借鉴意义。

The standard oxygen mass transfer coefficient(KLa20) was used as the evaluation index to investigate the influence of water flow velocity on the oxygenation performance of corundum microporous aerator under different gas flow rate capacity. The influence mechanism of water flow velocity on the oxygenation capacity of corundum microporous aerator was analyzed from the perspective of bubble Sauter mean diameter, liquid gas hold up and the hydromechanics. The results showed that, when gas flow rate was constant, the KLa20 of the corundum microporous aerator increased with the increase of the water flow velocity;with the increase of gas flow rate, the improvement of the KLa20 of corundum microporous aerator reduced with the increase of the water flow velocity;with the increase of the water flow velocity, the bubble Sauter mean diameter decreased, and the liquid gas holdup increased;the constructed clean water KLa prediction model for the oxygenation capacity of the corundum microporous aerator under the plug-flow conditions was in good agreement with the actual test results. The Froude number had a greater impact on the KLa of the corundum microporous aerator. The research results have certain guidance and reference significance for the engineering design of the actual aeration system of wastewater treatment plant.