环形流道叠片过滤器水头损失和过滤性能试验研究

    Enhanced experimental study on the head loss and filtration performance of annular flow disc filter

    • 摘要: 为探究直线形流道和环形流道叠片过滤器对水中泥沙的过滤能力,首先通过室内试验,测试两种过滤器在4种沙粒级配中值粒径(106、121、126和165 μm)、3种含沙量(0.10、0.15和0.20 g/L)和5种进口流量(1.5、2.0、2.5、3.0和3.5 m3/h)下的水头损失和过滤性能,然后以过滤器水头损失、堵塞均匀度、拦沙量、拦截泥沙粒径分布等作为评价指标,使用熵权法优选叠片结构参数。结果表明:清水条件下,环形流道叠片过滤器水头损失小于直线形流道叠片过滤器。含沙水条件下,直线形流道的叠片过滤器水头损失达到8 m时间较环形流道叠片过滤器延长10倍,且水头损失降幅最大达到52.5%,总拦沙量最大提高6.3%,中值粒径大于110 μm的配沙,平均拦沙量提高0.22%。该研究提出的环形流道可替代传统的直线形流道,在不降低过滤能力的前提下减小过滤器水头损失,延长反冲洗周期。

       

      Abstract: As a three-dimensional flow channel, the laminated filter has a complex structure, and it is easy to appear phenomena such as too short blocking time and increasing head loss caused by sand interception in the operation process. According to the relationship between head loss and cross-sectional area, an annular flow channel laminated filter was proposed. The circumferential flow channel was added on the lamination surface, which increased the flow direction of the flow channel and played the role of dividing the radial flow channel, achieving the purpose of hierarchical multi-layer filtration in the lamination and improving the number of available flow channels. In order to explore the advantages and disadvantages of the linear flow channel and annular flow channel laminated filter for irrigation water filtration capacity. Through indoor comparative experiments, 120 mesh laminated filter, namely the filter particle size of 125 μm was used to test the head loss and filtration performance of the two filters under four kinds of sand grading median particle size (106, 121, 126 and 165 μm), three kinds of sediment content (0.10, 0.15 and 0.2 g/L) and five kinds of inlet flow (1.5, 2.0, 2.5, 3.0 and 3.5 m3/h), a total of 60 groups of tests. The dependent variables were the head loss, the sediment retention capacity and the median particle size of the interception, and the independent variables were the inlet flow, the sediment concentration and the median particle size of the inlet. The evaluation indexes were the head loss, the plugging uniformity, the sediment retention capacity and the particle size distribution of the interception sediment. The multiple regression equation was established to verify the correlation between the head loss and the filtration capacity. The entropy weight method was used to determine the optimal lamination of the head loss and the filtration capacity. The results show that: under the condition of clear water, the maximum flow head loss of the annular flow laminated filter is 9.1% lower than that of the trapezoidal linear filter. Under the condition of sandy water, the time for the head loss to reach 8m is 1.5-10 times longer than that of the trapezoidal linear filter, and the maximum head loss is reduced by 52.5%. The total sediment retention capacity is increased by 0.5%-6.3%, and the average sand removal rate is increased by 0.22% for the sand with the median particle size greater than 110 μm. The siltation channels of the trapezoidal linear filter account for 25%-86% of the total number of channels of the trapezoidal lamination, while no siltation phenomenon is observed in the operation cycle of the annular lamination. The head loss of the two kinds of laminated filters was positively correlated with the sediment concentration, inlet flow and inlet median particle size, the sediment retention was positively correlated with the sediment concentration, inlet flow and inlet median particle size, and the interception median particle size was positively correlated with the sediment concentration and inlet median particle size. The annular flow channel laminated filter was more suitable for irrigation water with high sediment concentration and high median particle size distribution than the trapezoidal linear laminated filter. Therefore, the optimal laminated filter can be designed by considering the change of the geometric distribution of the flow channel of the laminated filter, which can reduce the filter head loss and extend its backwashing cycle without reducing the filtration capacity.

       

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