一种污水中砂粒高效采集装置的设计与试验
摘要:污水处理系统中的砂粒含量过高会造成设备磨损等很多负面影响,而如何对污水中砂粒含量进行快速并有效的检测是当前的盲区。本研究设计了一种自制连续流采样桶,其避免了单一取样时步骤繁琐等缺点,采用连续采样方法来进行对样品液的大量收集。对设计完成的采样桶模型进行CFD数值模拟试验,以此来探究其内部的流态和运行效率。试验结果表明,在进水流速为0.1m/s、进水砂粒的平均粒径为0.2mm的情况下,自制连续流采样桶对砂粒的截留效率为94.1%。对设计的采样桶制造后进行现场试验,发现其对砂粒的平均截留效率为96.8%。从数值模拟和现场试验的两方面结果来看,该连续流采样桶设计合理可靠,运行效率高,可用于实际生产。
关键词:CFD ; 采样装置;砂粒采集;数值模拟;连续采样
中图分类号:TU991 文献标识码:A 文章编号:1000-4602(XXXX)XX
Design and testing of an efficient collection device for sand in sewage
Abstract:In wastewater treatment systems,high grit levels can lead to negative effects such as equipment wear and tear, and there is a current blind spot in how to quickly and effectively detect grit levels in wastewater. In this study, a home-made continuous flow sampling bucket was designed, which avoids the disadvantages of tedious steps in single sampling and uses a continuous flow sampling method for the bulk collection of sample liquids. CFD numerical simulations were carried out on the designed sampling bucket model to investigate its internal flow regime and operational efficiency. The test results show that at an inlet flow rate of 0.1m/s and an average particle size of 0.2mm, the home-made continuous flow sampling bucket has a retention efficiency of 94.1%. The designed sampling bucket was manufactured and tested in the field and found to have an average retention efficiency of 96.8% for sand particles. The results from both the numerical simulation and the field test show that the continuous flow sampling bucket has a reasonable and reliable design and operates with high efficiency for practical production.
Key words: CFD;sampling devices;grit collection; numerical simulation; continuous sampling
在污水处理系统中,砂粒会造成污水停留时间减小、泵等设备的磨损[1]、污泥活性降低、剩余污泥的厌氧消化困难[2]等危害。除砂系统是砂粒去除的必要单元[3],评估污水厂除砂系统运行效率的关键方案就是对样品中砂粒含量的有效检测,而这前提是实现对样品液的有效收集。
为了保证所得数据结果的准确性和代表性,需要实行对样品液的大量收集,收集的体积通常在0.5m3以上。可以把污水样品液的收集方案分成两大类方法,即一次性取样方法和连续采样方法。一次性取样方法通常借助水桶等容器直接从水体采集出,相对方便,但每次采集的体积较少,如果多次采集则费时费力,相关方法在林杰[4]、董志杰[5]等人的论文中有所体现。而连续采样方法以连续流采样桶为代表,该装置的运行原理是让污水同时流进和流出,在这个过程中利用装置的结构特性实现对污水中砂粒的有效截留。这种方法的好处是受到样品液总量的限制很小,只要截留下的砂粒不充满装置底部,理论上可以实现对污水长时间的连续采集。
本研究则是以旋流分离设备为设计基础,利用旋流分离的原理,设计出了一种自制连续流采样装置。