内循环生物流化床曝气过程氧传质特性研究

Oxygen Mass Transfer Behaviors of the Aerating Process in Inner-loop Aerobic Biological Fluidized Bed Reactor

针对水-空气-高分子颗粒三相体系,测试了内循环好氧生物流化床曝气过程中气-液相间氧传递的体积传质系数KLa,分析了操作参数(进气量QG、固含率εs和升降流区截面积比Ar/Ad)对氧传质系数KLa的影响。结果表明,KLa随着进气量的提高呈线性增加趋势;固含率对KLa有正反两方面的作用,存在一个较适宜的固含率使氧传质效率达到最高;随升降流区截面积比Ar/Ad的增大,KLa随之提高。基于KLa影响因素的分析对实验数据进行拟合,建立了关于体积传质系数KLa的关联式:Kd=2.23×10-6Reb0.582Ab0.976εs0.016。该关联式预测结果与实验数据吻合良好,对类似流化床反应器的设计有一定参考价值。

To investigate the transfer behaviors of oxygen from the gas phase to the liquid in the aerating process of inner - loop aerobic biological fluidized bed reactors, experiments were performed under the system consisting of air, tap water and porous polymer particles, and the volumetric mass transfer coefficient （KLa） were measured. Then, the effects of operating parameters, including air flow rate, solid holdup and the cross - section area ratio of riser to down - comer, on the mass transfer coefficient （KLa） were analyzed. It follows that the coefficient KLa increases hnearly as the air flow rate rises; the solid holdup has both positive and negative effect on the value of KLa, and there exists an optimal solid holdup that allows the oxygen transfer to attain the maximum efficiency; when the cross - section area ratio is increased, the KLa becomes increased too. Finally, based the analysis, an empirical correlation of the KLa versus Reynolds number, the cross -section area ratio and solid holdup was developed. Comparison shows that the predicted results by the correlation are in good agreement with the experimental data.