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Thesis Advisor杨超 ; 李向阳
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline化学工程
Keyword微气泡 文丘里 进气方式 工程放大

气液两相或气液固三相体系广泛存在于化工、生物、石化、冶金和环境工程等工业中,气液传质往往是过程控制步,气体往往大量过剩,曝气动力消耗是总能耗的一个重要环节,一般占总能耗的1/3~1/2。微气泡具有比表面积大、停留时间长、气泡上升过程中基本不聚并等优点,有广泛的工业应用前景。 众多微气泡的生产方法普遍存在的产量小、能耗高等缺点,阻碍了微气泡的工程应用。本研究分析了各种微气泡产生方法的特点和机理,认为流体剪切型的文丘里式微气泡生产装置具有应用潜力。设计了一种文丘里式微气泡发生装置,并建立了远心照相分析方法,实验研究了表观气速、表观液速和进气方式(并流、错流和逆流)等操作条件对生成的微气泡直径分布的影响,同时还考察了表面活性剂浓度的影响。实验结果表明:表面活性剂在很大程度上改善了微气泡的稳定性,因此相同条件下产生微气泡直径相对更小,如进气管口处气速36.11 m/s、液速为9.44 m/s时,50 ppm的表面活性剂产生的气泡平均直径157.2 μm,比清水中气泡平均直径308.7 μm减小了49%;微气泡直径随气速降低和液速的增加而减小;在实验采取的逆流、并流、错流三种进气方式中,并流进气产生的气泡直径最小,表面活性剂浓度为50 ppm、表观液速(vl)为9.44 m/s、表观气速(vg)为36.11~54.16 m/s时,并流进气产生的气泡直径平均比逆流进气产生的气泡直径小11%。 为了推动微气泡的工程应用,对实验中微气泡生成装置进行了初步放大研究。按照喉管截面积与进出口截面积比例不变,入口收缩角和出口扩散角不变的准则将实验装置放大2倍,气泡产量增加一倍,相同条件下产生的气泡直径仍较为理想,如在清水中,液速7.08 m/s、气速18.05 m/s时产生的气泡直径为280.2 μm,相同条件下放大前产生的气泡直径为225.8 μm。

Other Abstract

Gas-liquid or gas-liquid-solid systems, in which the operation is often controlled by interphase mass transfer, are widely used in biological, chemical engineering, petrochemical technology, metallurgy and environment engineering, etc. The energy consumed on generating bubbles usually accounts for 1/3~1/2 of total power consumption. Microbubbles have large specific area, reside in liquid for a long time and hardly coalesce with each other during their motion. These advantages in favour of gas-involved reactions allow microbubble a great prospect in industrial applications. Until now, scientists have invented many devices to generate microbubbles, but all of them have the disadvantages of low yield and high power consumption, which hinders the industrial application of microbubbles. In this work, the characteristics and mechanisms of different generation methods are analyzed, and the Venturi microbubble generator of liquid driving type is found to have a wide application prospect. A Venturi microbubble generator is designed and a photographic method with a telecentric lense is proposed. The effects of superficial gas and liquid velocities and surfactant concentration on microbubble diameters and probability distribution function (PDF) by a Venturi microbubble generator are investigated. The experimental results show that microbubble diameter decreases with increasing liquid velocity and decreasing gas velocity. 

Document Type学位论文
Recommended Citation
GB/T 7714
李平平. 高效微气泡发生器的工程基础研究[D]. 北京. 中国科学院研究生院,2016.
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