加压溶气气浮气含率分布与气泡聚并规律研究

Gas Holdup Distribution and Bubble Aggregation in Pressurized Dissolved Air Floatation

加压溶气气浮技术是污水除油中常用的高效工艺,气泡的大小和分布对除油效率的影响至关重要。基于相群平衡模型,对溶气气浮器内两相流动及气泡聚并进行数值模拟,并进行实验研究加以验证,建立了气浮器接触区模型,研究了气泡聚并及气含率分布规律,分析了释放头不同气液比和接触区高度对气含率分布和气泡聚并情况的影响。结果表明:接触区气含率随气液比增大而升高,随接触区高度的增加而降低,气泡在上浮过程中会发生聚并使得气泡变大,稳定性变差,同时加快上浮速度,会影响接触区的气含率分布。通过微观模拟发现大粒径微气泡在上浮过程中更容易发生聚并,小粒径微气泡则由于表面张力作用稳定性更强,不易发生变形和聚并。研究结果为溶气气浮气液比的选择和浮选过程气含率和气泡分布的研究提供参考。

Pressurized dissolved air flotation is an efficient process commonly used in wastewater oil removal,and the effect of bubble size and distribution on oil removal efficiency is crucial.Based on the phase group equilibrium model,the two-phase flow and bubble aggregation in the dissolved air flotation device were simulated numerically and verified by experimental research,the contact zone model of the air floater was established,the bubble coalescence and gas holdup distribution were studied,and the effects of different gas-liquid ratio and contact zone height of the release head on the gas holdup distribution and bubble coalescence were analyzed.The results show that the gas content in the contact zone increases with the increase of gas-liquid ratio and decreases with the increase of contact zone height,and the bubbles will agglomerate during the floating process,making the bubbles larger and less stable,and accelerating the floating speed,which will affect the gas content distribution in the contact zone.The microscopic simulation shows that large-sized microbubbles are more likely to be aggregated during the floating process,while small-sized microbubbles are more stable and less likely to be deformed and aggregated due to surface tension.The research results provide a reference for the selection of dissolved air flotation gas-liquid ratio and the study of gas content and bubble distribution in flotation process.