进水流量和曝气强度对管式曝气池液相流态及氧传质特性的影响

Effects of inlet flow rate and aeration intensity on liquid flow state and oxygen mass transfer characteristics of tubular aeration tank

利用粒子图像测速技术(PIV)和溶解氧在线测试仪对管式曝气池在不同进水流量和不同曝气强度工况下的液相流态和氧传质特性进行了测定。结果表明,管式曝气池在相同曝气强度下,氧转移系数和氧转移效率均随着进水流量的增加而逐渐增加;而在相同进水流量时,氧转移系数和氧转移效率均随曝气强度的增大呈先下降后逐渐上升的趋势。综合考虑理论和实际情况,PIV测量时曝气强度选择0.750m3/h。当进水流量为0.234m^3/h时,管式曝气池上中下3个区域的涡量面积分布最均匀,液相死区最少,说明此时气液两相混合程度最好。因此,管式曝气池的最佳进水流量确定为0.234m^3/h。

Liquid flow state and oxygen mass transfer characteristics of tubular aeration tank were measured under different inlet flow rate and different aeration intensity using particle image velocimetry （PIV） and dissolved oxygen online tester. Results showed that oxygen transfer coefficient and oxygen transfer efficiency in tubular aeration tank increased with the increase of inlet flow rate when aeration intensity was the same,while those decreased firstly and then increased with the increase of aeration intensity when inlet flow rate was the same. Considering both theoretical and practical conditions,0.750 m3/h was selected as aeration intensity for PIV measurement. When inlet flow rate was 0.234 m3/h,vorticity distribution tended to be the most homogeneous,and liquid dead area tended to be the least for the 3 areas of top,centre and bottom of the tank. That is to say,0.234 m3/h should he selected as the best inlet flow rate since this condition made liquid phase and gas phase mixed adequately.