多级复合网式过滤器水力性能试验研究

多级复合网式过滤器是将不同目数的滤网(50、80、120目)集成在同一壳体以增加其过滤效果的微灌用过滤器。【目的】研究该过滤器性能。【方法】开展清水试验,考察过滤器清洁压降变化;开展浑水试验,以流量和含沙量为因素,其中,流量设置18、22、26m³/h,含沙量设置0.07、0.10、0.13g/L,考察水头损失、流量、浊度等指标变化规律。【结果】清水试验时,过滤器清洁压降曲线符合幂函数关系,拟合系数0.9999;浑水试验时,流量起初较稳定,约18~30min后出现拐点而急剧下降;相对应的,过滤器水头损失则起初稳定,出现拐点后急剧增大,流量和含沙量越大,流量和水头损失变化的拐点出现越早,过滤周期越短,过滤器发生堵塞的时间越短,但发生堵塞后,浊度出现降低趋势,预示过滤效果更好。【结论】新研发的多级复合网式过滤器(壳体内径370 mm,高720mm)水力性能变化规律与单一网式过滤器类似,而且过滤周期较长,过滤精度较高,适用于微灌系统。

Experimental Study on the Hydraulic Performance of a Multi-stage Composite Mesh Filter

【Objective】The multi-stage composite mesh filter is a new micro-irrigation filter we developed recently by integrating the meshes of 50,80 and 120 in the same casting aimed to increase the filtering efficacy.The purpose of this paper is to present the results of an experimental study on its hydraulic performance.【Method】The experiment consisted of two parts.The first one used clean water in which we measured the water pressure drop across the filter.The second one was used muddy water to elucidate the combined impact of water flow rate and sediment content on hydraulic performance of the filter.We compared three flow rates:18,22 and 26 m³/h,combined with three sediment contents:0.07,0.10 and 0.13 g/L.In each treatment,we measured water pressure loss,change in flow rate,as well as turbidity of the water at the exit of the filter.【Result】Pressure drop of the clean water across the filter increased with water flow rate in a power-law with a R2 of 0.9999.In the muddy water test,the flow rate was initially stable with the inflection point appearing about 18min-30min after inception of the experiment,after which it dropped sharply.Associated with such a flow rate change,the pressure loss across the filter was also stable at beginning,followed by a steady increase after the inflection point.It was found that the higher the flow rate and/or the sediment content was,the earlier the inflection point appeared for both flow rate and pressure loss,and that the clogging time was positively correlated to the duration of the filtration cycle.However,after the clogging,the turbidity of the effluent decreased,indicating an improved filtration effect.【Conclusion】The new multi-stage composite mesh filter we developed has a similar hydraulic performance as the single mesh filter,and it prolonged the filtration cycle thereby improving the filtration efficacy.It thus suits micro-irrigation systems.