| The filter is the key equipment for processing the sediment in the micro-irrigation water source,which can ensure the normal operation of the micro-irrigation system.However,most of the filter operation methods are high-pressure filtration and flushing after the pump,which has problems of high energy consumption,large investment.and difficult to clean.Therefore,a new filtering measure for the micro-pressure filtration and flushing before the pump is the Pool of Filtering and Washing under Micro-pressure(PFWMP).In this paper,the head loss is used as the hydraulic performance assessment index,and the sediment removal rate.Filter screen to intercept the weight of sediment and filtration time are used as the filtration performance assessment index.A physical model test of the PFWMP is carried out.The test data is processed using Data Processing System(DPS)and Projection Pursuit Regression(PPR)statistical software.The filtering performance of the PFWMP under two filter materials was discussed.The calculation formula of the head loss of the PFWMP was established by using dimensional analysis.Based on this,a uniform orthogonal test of sediment concentration,flow rate and screen area was carried out.The main factors affecting the filtration performance of the PFWMP were determined.The filtration performance assessment indicators were established with the same sediment concentration,flow rate and filtration the response relationship of the mesh area,a combination of factors to achieve the optimal conditions of the PFWMP.The research results will provide technical support for the popularization and application of the PFWMP in the sediment treatment of the first micro-irrigation hub,and enrich the micro-pressure filtration theory.The main research results of this article are as follows:(1)When the sediment concentration is 0.36-1.17kg/m3 and the flow rate is 3-7m3/h,the sediment removal rate of the acrylic filter is 60-80%,and the sediment removal rate of the stainless steel filter is 40-60%,the former is 1.33-1.50 times the latter.The weight of sediment intercepted by the acrylic filter is 1.17-1.65 times that of the stainless steel filter.The filtration time of the stainless steel filter is slightly longer than the acrylic filter.Comprehensive consideration of the filtration performance assessment indicators,acrylic filter is more suitable for the PFWMP.(2)Under the sediment concentration of 0.36-1.17kg/m3,the flow rate of 3-7m3/h,and the confidence level of 95%,the determination coefficients R2 of the calculation formulas for the head loss of fresh water and muddy water in the PFWMP test device are 0.957 and 0.990.The formula is reliable.(3)The sediment removal rate of the PFWMP is not greatly affected by the flow,but it will increase with the increase of the sediment concentration.The sand interception weight of the filter screen increases with the increase of sediment concentration and flow rate.The smaller the sediment concentration and flow rate,the longer the filtering time.The PFWMP has three filtration stages:filter filtration.filter cake filtration and squeeze filtration.(4)The primary and secondary order of factors affecting the sediment removal rate of the PFWMP is filter area,flow rate,sediment concentration;the factors that affect the weight of sand interception are primary and secondary order:filter area,sediment concentration,flow rate;The primary and secondary order of the factors affecting the filtration time is flow rate,sediment concentration,screen area.(5)The established sand content,flow rate,screen area and the PFWMP filtration performance evaluation index prediction model,the modeling and the qualified rate of the reserved samples are 100%,and the model is reliable.And it is predicted that the combination of test factors that achieve the optimal working conditions of the PFWMP test device is a sand content of 0.36 kg/m3,a flow rate of 4m3/h.and a screen area of 2000 cm2. |
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