导流及布气方式对膜生物反应器内部流场影响的数值模拟分析

Effect of the diversion and aeration mode on the flow field of membrane bioreactor by numerical simulation

运用数值模拟,研究膜生物反应器中曝气管路布气位置及导流板对反应器内流场分布的影响,并对3种气水比(10∶1、15∶1、20∶1)进行了优化研究.将模拟结果进行比较发现:"对齐"布气优于"间隔"布气;导流板对反应器内流场特性有较明显的影响,导流作用能有效地改善反应器内气含率的分布状况,提高氧传质效率,增大膜面剪切速度.在相同条件下,其平均膜面剪切速度分别是不加导板的"对齐"和"间隔"布气方式的1.5和1.9倍.当气水比为15∶1时,各种布气方式反应器内气含率分布均较大,流场内的涡流均非常明显,整个场内形成了循环流动,膜面剪切速度也达到最大.

A two-dimensional CFD （computational fluid dinamics） simulation, using two-fluid model, was performed to research the effect of aeration pipeline location and the baffle on the flow field in the membrane bioractor. An optimization reseach was carried out for the reactor under three kinds of the gas- water ratio （10 ： 1, 15 ： 1, 20 ： 1）. The results show that the ＇alignment＇ gas distribution is better than ＇interval＇. The baffle has an obvious effect on the flow field in the reactor. It can not only effectively improve the reactor＇s gas hold-up distribution and the oxygen mass transfer efficiency, but also increase membrane surface flow rate. The average shear rate is 1.5 ~ 1.9 times higher than that without baffle under the same conditions. And when the gas-water ratio is 15 ： 1, the gas hold-up distribution of all kinds of ways is large, the vortex in the flow field is very obvious, a circular flow could form in the whole field, the membrane surface flow rate is the highest.