污水厂气提式内回流影响因子试验

污水厂硝化液内回流通常采用浆叶泵，因安装台数有限间接地限制了回流比的调节幅度，当水质波动较大时难以实现精确回流。气提式回流通过改变气升管组数即可实现回流比的多工况精确调节，对污水厂节能降耗意义显著。本试验模拟研究污水厂内回流工况下，通气量q、管长L和管径d对气提泵提升性能斜率的影响规律。研究结果表明:气提泵扬水能力Q与通气量q的拟合曲线呈近似抛物线，越过峰值后气提泵效率显著下降; 增大淹没比有利于增大扬水量，淹没比-扬水量曲线DN100的比DN80大; 在工程应用实践中，根据实际情况，选用小长径比($\frac{L}{D} \le 50$)的管长和管径的配比; 淹没比在0.7、0.75、0.8、0.85和0.9时，升力效率曲线随着空气流量的增加而持续下降，效率随着淹没率的增加而下降。最后，通过建立fluent模型进行验证，得出模拟结果与实验结果一致，证明实验结果是准确的。

Experimental Study on the Influence Factors of Air-lift Circulation Reflux in Sewage Plant

The circulation reflux in nitrification liquid of sewage plant usually adopts slurry pump, which indirectly limits the adjustment range of circulation reflux ratio due to the limited number of installed tables. It is difficult to achieve accurate circulation reflux when the water quality fluctuates greatly.By changing the number of air risers, air lift reflux can be adjusted accurately under multiple working conditions.Experiments were carrried out to simulate the circulation reflux conditions in the sewage plant. Then the influence of ventilation q, pipe length L and pipe diameter d on the lift performance of the air lift pump under the conditions were studied.The results show that the fitting curve of the delivery Q and the ventilation q presents a parabola, and the efficiency of the pump decreases significantly after the peak value. Increasing the submerged ratio is helpful to increase the delivery, and the slope of DN100 curve is larger than that of DN80. It is better to choose the proportion of pipe length and pipe diameter with small length-diameter ratio ($\frac{L}{D} \le 50$). When the submergence ratio is 0.7, 0.75, 0.8, 0.85 and 0.9, the lift efficiency curve continues to decline with the increase of air flow rate, and the efficiency decreases with the increase of submergence rate. Fluent model was established, and the simulation results were consistent with the experimental results. This indicates that the experimental results were accurate.