曝气条件下应用型氧化沟内混合液流态测试及分析

Test and analysis on flow pattern of application scale oxidation ditch

从氧化沟的水力特性入手,实测并分析了混合液在应用型氧化沟内的流态分布特点。结果表明,在曝气机不同的旋转条件下,混合液液流在氧化沟内的流态分布规律具有较高的相似性,上部液流经曝气机加速作用,流速在短时间内急剧增加,而下部液流速度变化不明显,液流随之在沟体内进行流速均布,在返回第一直道时不同水深和内外侧流速已基本达到一致;混合液液流除了受到曝气机的推动力作用外,还受到沟体沿程阻力及弯道局部阻力的作用,导流板对混合液流态也产生了影响;在1.56m水位、120r/min逆时针转动条件下,第一直道末端下部液层内侧与中侧的流速较低,成为沟底污泥淤积的危险区;当转速为100r/min时,能保证氧化沟底混合液流速不小于0.15m/s;在1.56m水位、80r/min顺时针转动条件下,能保证氧化沟底混合液流速不小于0.15m/s。在实际运行中,只有将曝气设备调节到适合的转速才能有效防止污泥在氧化沟沟底沉积。同时,在保证沟底混合液流速满足要求时,为节省动能损耗,还应选择较低的曝气机转速。

The performance of oxidation ditch was directly influenced by the mixture and circulation of inpoured wastewater. Therefore,it is significant to study the velocity distribution and flow characteristic of oxidation ditch theoretically as well as practically. The batch running of application scale oxidation ditch was investigated to determine the effect of operating conditions on flow pattern in oxidation ditch,the fluid velocity distribution rule in straight sections and curved sections of oxidation ditch was also obtained. The optimal rotational speed was 100 r/min for anticlockwise direction or 80 r/min for clockwise one. The results can provide basis conditions for preventing sludge accumulation,optimizing operation parameters and saving energy consumption. At the same time,the oxidation ditch is also an actual project exemplification.