自清洗网式过滤器水头损失和排污时间研究

Experiment on Head Loss and Discharge Time of Self-cleaning Screen Filter

通过室内模型试验,对80目和120目自清洗网式过滤器在清水过滤时的水头损失和排污状态下的最佳排污时间进行了试验研究。清水过滤状态时,通过对试验用过滤器的进水口和出水口建立伯努利方程,推导出过滤器清水水头损失的通用表达式,在不同的进水流量下(0～220 m3/h),结合试验数据得出了2种目数滤网水头损失的经验表达式;排污状态时,在对2种滤网各自设置5个不同排污压差及3个相应不同进水含沙量条件下,得出了排污口含沙量随排污时间的变化曲线规律为先变大后减小,15 s时出现拐点,20 s以后趋于稳定,为保证过滤器的排污效果及节约水资源,确定过滤器的最佳理论排污时间段为20～30 s,结合试验数据和误差分析,理论推导出120目滤网的最佳排污时间计算表达式,计算结果表明:理论值与试验值吻合较好。

Based on the indoor model test, the head loss in the clear water filtration and optimal drainage time in the pollution state of the 80 mesh and 120 mesh self-cleaning screen filter was studied. The results showed that in the filtering state, general expression of clean water head loss was deduced through establishing Bernoulli equation from inlet to outlet of the filter. Two mesh head loss experience expression was obtained under different water flows （0 -220 m3/h）. In the drainage conditions of two filters with five different discharge pressure differentials and three corresponding different sediment concentration, the rule of the curve showed that water sediment concentration of the drain changes with drainage time increasing at first and then decreasing. An inflection point appeared at 15 s, and the outfall＇s sediment tended to stabilization when the discharge time reached to 20 s. To ensure the effect of discharge of the filter and saving water, the optimal discharge time of the filter was set to 20 - 30 s in theory. Based on the experiments and error analysis, the optimal discharge time expression of 120 mesh filter＇s was deduced. The results showed that the values of theory and test agreed well.