自清洗网式过滤器水力性能试验

Experiment on hydraulic performance of self-cleaning screen filter

通过清水试验和浑水试验对自清洗网式过滤器的水力性能进行了试验研究.清水试验主要研究过滤器的局部水头损失随不同进口流量(0～230 m3/h)的变化情况.浑水试验分别对过滤器的过滤状态和排污状态进行研究:过滤状态主要研究在最大进水流量(230 m3/h)下改变不同进水含沙量时的局部水头损失变化,以及在保持相同进水含沙量(0.19 g/L)下改变不同进水流量时的局部水头损失变化;排污状态重点研究在不同预设压差值下最佳排污时间的变化规律.试验结果表明:对于清水过滤,进水口流量值在0～140 m3/h变化时,对应的过滤器初始局部水头损失变化缓慢;当流量在140～230 m3/h时,局部水头损失增加较快,并拟合出水头损失经验公式.对于浑水过滤,改变不同进水含沙量值,局部水头损失均在6～7 m出现拐点,之后迅速增大,确定其预设排污压差值为0.07 MPa;排污过程中,当排污时间达到20 s时,排污管出水含沙量趋于稳定,排污效果较好,确定其最佳排污时间段为20～30 s.

The hydraulic performances were experimented by using clean and muddy water, respectively. The filter minor head loss coefficient was measured at various flow rates （0 -230 m^3/h） for clean water. The filter sand filtration and drainage behaviors were studied in muddy water. Firstly, the minor head loss coefficients were measured at various sand concentrations in the muddy water at the highest flow rate 230 m^3/h. Secondly, the coefficients were tested once again at various flow rates for a constant sand concentration of 0.19 g/L. The optimal periods of time for discharge of sands were measured at a series of given pressure differentials across the filter, however, for the drainage behavior. The resuits show that for the clean water the coefficient is increased slowly in increasing flow rate in 0 - 140 m^3/h, however, it rises rapidly when the flow rate is 140 -230 m^3/h. The empirical formulas have been proposed based on those head loss experimental data. For the muddy water, once the head loss is beyond 6 -7 m, the loss will be increased rapidly with sediment concentration. During the experiments on drainage behavior, when the period of time for drainage sand reaches 20 s, the sediment concentration downstream tends to keep stable and a good result is achieved sand drainage, suggesting the optimal drainage time is in 20 - 30 s under the given pressure difference of 0.07 MPa across the filter.