袁寄望, 朱德兰, 高洒洒, 孙少博, 赵航, 张锐. 叠片过滤器水头损失变化规律及杂质拦截特征[J]. 农业工程学报, 2022, 38(13): 114-122. DOI: 10.11975/j.issn.1002-6819.2022.13.013
    引用本文: 袁寄望, 朱德兰, 高洒洒, 孙少博, 赵航, 张锐. 叠片过滤器水头损失变化规律及杂质拦截特征[J]. 农业工程学报, 2022, 38(13): 114-122. DOI: 10.11975/j.issn.1002-6819.2022.13.013
    Yuan Jiwang, Zhu Delan, Gao Sasa, Sun Shaobo, Zhao Hang, Zhang Rui. Head loss variation and impurity interception characteristics in a disc filter[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2022, 38(13): 114-122. DOI: 10.11975/j.issn.1002-6819.2022.13.013
    Citation: Yuan Jiwang, Zhu Delan, Gao Sasa, Sun Shaobo, Zhao Hang, Zhang Rui. Head loss variation and impurity interception characteristics in a disc filter[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2022, 38(13): 114-122. DOI: 10.11975/j.issn.1002-6819.2022.13.013

    叠片过滤器水头损失变化规律及杂质拦截特征

    Head loss variation and impurity interception characteristics in a disc filter

    • 摘要: 为避免叠片过滤器在工程应用中出现水头损失激增导致过滤器频繁冲洗造成水量和能量损耗现象,该研究对5种流速(0.37、0.40、0.43、0.46和0.49 m/s)、5种沙粒浓度(0.10、0.15、0.20、0.25和0.30 g/L)与5种沙粒级配的中值粒径(49、66、82、100和127 μm)条件下叠片过滤器的水力性能和过滤性能开展全试验。根据不同工况下过滤器的水头损失、拦沙量、拦截沙粒粒径以及拦截沙粒位置分布情况,利用回归分析法确定了清水和含沙水条件下水头损失的计算方法,探究不同沙粒粒径范围引起水头损失显著增加的敏感流速和水头损失变化原因,并分析叠片流道拦截沙粒粒径及拦截沙粒位置分布。结果表明:1)清水条件下过滤器局部水头损失系数为一定值,水头损失仅与有效过水面积有关,含沙水条件下水头损失与流速和沙粒浓度相关,并得出三者之间的关系,决定系数达到0.90以上;2)0~50、>50~75、>75~100、>100~125和>125~150 μm的沙粒粒径引起水头损失显著增加的敏感流速分别为0.37、0.40、0.43、0.46和0.49 m/s;3)水头损失和拦沙量的相关性较强,二者在沙粒粒径越大的含沙水下受流速的影响程度越小;4)0~65 μm的沙粒可穿出流道,>65~100 μm的沙粒能够被流道截留,叠片拦截最小沙粒粒径与流道最小截面内切圆直径关系为1∶1.8,>100~125 μm的沙粒易堆积流道进口处,>125~150 μm的沙粒无法进入叠片。研究可为不同灌溉参数设置下合理配置和使用叠片过滤器提供参考。

       

      Abstract: A disc filter has been rapidly and widely applied in the irrigation field in recent years owing to its composite three-dimensional filtering and the filtering characteristics of both screen filter and sand filter. Therefore, it has presented a promising application prospect in the very broad filtration system worldwide. However, the head loss of the disc filter can increase sharply within the critical range in a short time, due to the complex channel structure and uneven channel clogging during operation. Therefore, frequent backwashing can increase the water volume and energy consumption, and leading to the low operating efficiency of the whole micro-irrigation system. Thus, it is a high demand to elucidate reasons for the head loss increasing sharply of the disc filter. This study aims to avoid the steep increase in head loss for the higher operation efficiency of the filtering system, the hydraulic and filtration performance of the disc filter was tested on five flow velocities (0.37, 0.40, 0.43, 0.46, and 0.49 m/s), five sand concentrations (0.10, 0.15, 0.20, 0.25, and 0.30 g/L), and five compositions of median particle sizes in sand (49, 66, 82, 100, and 127 μm). Some indexes were determined, including the head loss, the sand interception, the particle size of intercepted sand, and the position distribution of intercepted sand in the laminated channel of the filter under different working conditions. The methods for calculating the head loss were established under the clean and sand water conditions using regression analysis, respectively. A Malvern particle size analyzer was utilized to determine the sensitive particle size, which was caused by the fluctuation of the head loss under the different flow velocities and the particle size of laminated intercepted sand. In addition, the position distribution of intercepted sand was also characterized by an optical microscope. The results showed that the average local head loss coefficient was achieved at 290.60 under the clean water condition. It illustrated that the head loss was only related to the effective water-crossing area. The correlation between the head loss and flow velocity, and sand concentration was high (R2>0.90) under the sand water with different gradations. Moreover, the sensitive flow velocity of head loss outstandingly increased by 0.37, 0.40, 0.43, 0.46, and 0.49 m/s, respectively, when the sand size in sand water was in the range of 0-50, 50-75, 75-100, 100-125, and 125-150 μm. There was a strong correlation between the head loss and sand interception, and sand size was greater in the sand water, where both were less affected by the flow velocity. Furthermore, the fine sand with 0-65 μm easily passed through the channel without any interception, whereas, the sand with 65-100 μm was intercepted by the laminated channel. There was a ratio of 1:1.8 between the actual filtration accuracy of the lamination and the diameter of the inscribed circle in the minimum section of the channel. Specifically, the sand with the size range of 100-125 μm was possible to enter the laminated channel. Correspondingly, the sand was easily accumulated at the inlet of the channel, indicating the relatively low sand intercepted capacity of the filter. By contrast, the sand with 125-150 μm cannot enter the laminations. In conclusion, the finding can provide a strong reference for the rational configuration and use of disc filters under different irrigation parameters and water quality conditions, such as the flow velocity, sand concentration, and size composition.

       

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