气升式多通道膜反应器气促湍动过程的研究

A study on gas promoted turbulent process of airlift multi-channel membrane reactor

构建了气升式多通道膜反应器(ALMR)的气升过程模型,分析了气升通道和曝气量QG等参数对流体气含率ε、气升液速v_L的影响。结果表明在实验条件下,ε随QG和气泡尺寸的增大而增大;扩大气升通道直径可有效提高气泡上升速率,降低流体的ε,随着导流筒长度h的增大ε减小,气速较液速增长更快,且该现象随QG的增大更为显著;气升过程存在剧烈的搅混作用,随着QG的增大,液流量QL和vL逐渐增大并趋于稳定液体气升方向动能较曝气输入功低了2个数量级,过程的耗散功△E则呈近线性增长;△E/h保持稳定不随h的变化而变化。

A mathematic model is built for the airlift process of an airlift multi-channel membrane reactor(ALMR).The influences of the airlift channel,aeration rate(QG)and other parameters on the gas holdup and airlift velocity in ALMR are investigated.The experimental results show that the gas holdup increases with the increases of aeration rate and bubble size.Increasing the diameter of the airlift channel can effectively accelerate the lifting velocity of bubble and reduce the fluid’s gas holdup.With the increasing length of the draft tube,the gas holdup decreases and the gas velocity increases faster than the liquid velocity.Furthermore,this phenomenon is dramatic with the increasing aeration rate.Violent mixing occurs during the process of airlift.As QG increases,both the liquid flow QL and the liquid velocity increase sharply at the beginning and tend to be stable quickly.The kinetic energy in the direction of liquid air lift is two orders of magnitude lower than that in the direction of aeration inlet.In the experimental process,is linear relationship between dissipation energy(△E)and aeration rate.The ratio of△E to the height of the outlet of the draft tube h can keep stable,△E/h will not change with the change of h.