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过程工程学报 ›› 2019, Vol. 19 ›› Issue (4): 676-684.DOI: 10.12034/j.issn.1009-606X.218305

• 流动与传递 • 上一篇    下一篇

微曝氧化沟气液两相传质模型构建及传质影响因素分析

刘凤霞, 李永强, 许晓飞, 董 鑫, 刘志军*   

  1. 大连理工大学
  • 收稿日期:2018-11-01 修回日期:2018-12-12 出版日期:2019-08-22 发布日期:2019-08-15
  • 通讯作者: 李永强
  • 基金资助:
    国家自然科学基金项目;教育部留学回国人员科研启动基金项目;辽宁省博士科研启动基金项目

Model construction and influence factor analysis of gas-liquid mass transfer in a fine-bubble oxidation ditch

Fengxia LIU, Yongqiang LI, Xiaofei XU, Xin DONG, Zhijun LIU*   

  1. Research & Design Institute of Fluid and Powder Engineering, Dalian University of Technology, Dalian, Liaoning 116024, China
  • Received:2018-11-01 Revised:2018-12-12 Online:2019-08-22 Published:2019-08-15

摘要: 基于ANSYS Fluent软件建立了微曝氧化沟气–液两相流动和溶解氧输运模型,对比不同工况下氧体积传质系数的实验测量值和模拟结果,误差在7%以内。采用验证可靠性的模型模拟研究了气泡直径、曝气量和横向流动速度对微曝氧化沟内氧传质的影响。结果表明,气泡直径由1.5 mm增至3 mm时,氧体积传质系数由15.80 h?1降低至5.83 h?1;曝气量由0.5 m3/h增大至2 m3/h时,氧体积传质系数由4.21 h?1增至14.15 h?1,减小气泡直径和增大曝气量能明显提高氧体积传质系数。微曝氧化沟内气–液相间传质及溶解氧的分布受横向流动影响,开启单台和两台推流泵时,氧体积传质系数分别比无横向推流工况增大27.7%和42.4%,横向流动能有效提高气泡羽流内的气含率,增强氧传质效果。

关键词: 气液两相流, 传质, 数值模拟, 气含率, 微孔曝气, 横向流动

Abstract: The gas–liquid flow model and dissolved oxygen transport model in a fine-bubble oxidation ditch were established based on ANSYS Fluent software. Reliability of the model was verified under different operating conditions. The deviation between volumetric mass transfer coefficient obtained by simulation and experiment was less than 7%. Then, the effect of bubble diameter, aeration flow rate and transverse flow intensity on oxygen mass transfer were investigated by the verified model. The results indicated that as the bubble diameter increased from 1.5 mm to 3 mm, the volumetric mass transfer coefficient decreased from 15.80 h?1 to 5.83 h?1 and as the aeration flow rate increased from 0.5 m3/h to 2 m3/h, the volumetric mass transfer coefficient increased from 4.21 h?1 to 14.15 h?1. The volumetric mass transfer coefficient could be considerably improved by decreasing the bubble size and increasing the aeration flow rate. The distribution of dissolved oxygen and effect of oxygen mass transfer in the oxidation ditch would be affected by transverse flow intensity. Compared with operational condition with aerating only, the volumetric mass transfer coefficient increased by 27.7% and 42.4% respectively when single and double impellers were introduced in combination with aerating. The transverse flow could enhance the gas holdup in bubble plume and thus improve the effect of oxygen mass transfer.

Key words: gas-liquid flow, mass transfer, numerical simulation, gas holdup, micro-aeration, transverse flow