【作者】 杨春娣；

【导师】 程文；

【作者基本信息】 西安理工大学 ， 环境工程， 2008， 硕士

【摘要】 曝气生物滤池(BAF)工艺是一种新型的污水处理工艺,国内外学者对曝气生物滤池的研究在曝气生物滤池的影响因素如水温、水质、pH值等方面取得了一定的进展和共识,但有关曝气生物滤池中气液两相流的运动机理等方面的问题还有待进一步研究现阶段由于技术条件的限制都未能全面阐述与气液两相流运动有关的溶解氧的分布规律,在曝气生物滤池的实际应用中需要这方面的理论指导,因此实验研究和测量气液两相流场非常重要。本文从两相流的主要参数测量入手,采用数值模拟及实际的污水处理实验相结合的方法研究曝气生物滤池中不同曝气方式对生活污水处理效率的影响。数值模拟的结果得到了不同曝气方式下气液两相流的流场及两相流中气液两相的分布情况。本文设计了一套曝气生物滤池的实验模型装置,采用粒子图像测速技术对装置中不同状态的流场进行了测量,获得了不同流动状态下装置中的气泡平均速度。再利用所得的气泡速度及已知的参数作为边界条件,模拟得到不同曝气条件下的气液两相流速分布。将模拟的各种曝气状态应用到实际的污水处理中,在固定的时间点测定处理中的污水的COD指标,验证数值模拟的结论。实验最终得出几种曝气方式中的最优形式,为曝气生物滤池实际应用中曝气方式的确定提供理论依据。本文得到结论主要有:(1)研究两相流运动特征可以从实验研究两相流主要参数入手,采用粒子图像测速技术可得到具体的参数值,为数值模拟提供边界条件。(2)FLUENT软件模拟出不同状态下的气液两相流场,分析模拟结果得出的结论与实际的实验一致。(3)对于曝气孔径、气流速度、水深纵横比三种因素,改变其中任一种因素都会引起流场中的气泡体积、气相分布等的变化。(4)在本实验条件下,当水深纵横比h/w=1,曝气孔径最小d=0.6mm,气流速度最大v=0.3m/s,模拟的气液两相流场中气相分布最均匀,两相流紊动强度较大,气液混合最充分,曝气方式为最优。更多还原

【Abstract】 Biological aerated filter is a new technology of wastewater treatment. Scholars national and abroad have researched the factors like temperature, water quality and pH value. They have made agree with each other on all of these points, however, researches on the movement law for gas-liquid two-phase flow in biological aerated filter is lack, the oxygen transfer efficiency, momentum and energy between phase as well as the interaction among turbulent components are all unclarified, applications of biological aerated filter also need theory, so it is especially essential to measure the velocity field. This research begins with parameters of two-phase flow and establishes the influence of aeration type in treating wastewater by means of the combination of experimental research and numerical simulation on the gas-liquid two-phase flow.This paper designed a set of biological aerated filter. Particle Image Velocimetry technique was used to study gas-liquid two-phase flows. Take the bubble velocity as a boundary condition, gas-liquid two-phase flow velocity field of different conditions obtained. Measured chemical oxygen demand at specific moment, results of numerical simulation was verified. Finally this paper proposed the most effective aeration pattern.The main results in this paper are listed as follow:(1) Researches about two-phase flow can begin with parameters, particle image velocimetry technique method can be used to complete the numerical simulation.(2) FLUENT software simulated two-phase flow velocity field accurately. The resultsconsistent with experiment.(3) With the change of diameters of capillary tubes, bubble velocity, ratio of aeration tank et al, bubble volume and distribution of gas phase changed simultaneously.(4) When the ratio of aeration tank h/w=1, diameter of capillary tubes is smallest, the bigger the bubble velocity, the two-phase gas-liquid mixing more strong, turbulent intensity getting bigger, more fully makes gas-liquid mass transfer, the higher the efficiency of sewage disposal we can get.更多还原