新型双层平流沉淀池构造与流场特性研究

发布时间：2018-04-11 01:40

本文选题：双层平流沉淀池 + 固体悬浮物　；参考：《石河子大学》2017年硕士论文

【摘要】：沉淀池是利用重力作用去除水中悬浮物的一种构筑物。随着双层平流沉淀池在国内一些水厂投入使用,对双层平流沉淀池结构进行优化,提高沉淀池净水效果对于提高我国水资源和土地利用率具有现实意义。本研究中对现有的双层平流沉淀池进行改进,设计了两个新型斜板构造双层平流沉淀池:下向流斜板构造双层平流沉淀池(模型A)和上向流斜板构造双层平流沉淀池(模型B),以及一个串联式双层平流沉淀池(模型C),并制作了三个沉淀池模型。通过结合石河子地区河流来水状况展开模型试验,并对模型内流场进行数值模拟,综合分析模型试验与数值模拟结论,主要取得的研究成果有:(1)本文详细介绍了新型斜板构造双层平流沉淀池的设计原理与沉淀池模型的设计参数,可以为后续双层平流沉淀池的设计与研究提供一个参考。相同水力条件下,未添加絮凝剂与添加絮凝剂后的试验结果均表明模型A的沉降效果优于模型B和模型C。(2)未添加絮凝剂试验中,沉淀池初次运行过程中,从刚刚出流到出流水质趋于稳定是一个渐变的过程,三个双层平流沉淀池从开始出流到出流稳定的时间间隔为120 min左右。设计的两类新型斜板构造双层平流沉淀池,在水厂预处理车间持续运行48 h后,运行工况良好,出水水质稳定,可以满足实际工程中沉淀池持续运行的要求,均能够达到较为理想的去除效果。对于高浊度来水,为了保证较高的出流固体悬浮物去除率,该新型双层平流式沉淀池中模型A的水力停留时间宜设置为70 min,模型B的水力停留时间宜设置为80min。(3)添加絮凝剂后,当出流趋于稳定以后,模型A的平均出水浊度均较模型B和模型C的平均出水浊度低,模型A在降低出水浊度方面,优于模型B和模型C。在出流趋于稳定的过程中模型A的固体悬浮物去除率与模型B的固体悬浮物去除率较接近,加入絮凝剂后各组试验均表明三个沉淀池模型出流固体悬浮物去除率较接近,说明双层平流沉淀池的固体悬浮物去除率与其底板倾角大小无明显相关性,流量参数对双层沉淀池固体悬浮物去除率影响较小。(4)对双层沉淀池在不同流量下的流场分布进行了二维模拟,通过对沉淀池的流场分布图进行分析,可以得出模型A的流场分布较模型B和模型C均匀,模型A回流区和死水区面积均小于模型B和模型C,模型A流场特性优于模型B和模型C,该结论与模型试验得到的结论模型A的沉降效果优于模型B和模型C相吻合。设计的三个双层平流沉淀池在入流区存在较大面积的紊流区,可以通过合理布设调流板开孔孔洞等措施解决。
[Abstract]:Sedimentation tank is a structure used to remove suspended matter in water by gravity.With the application of the double-layer advection sedimentation tank in some domestic water plants, it is of practical significance to optimize the structure of the double-layer advection sedimentation tank and improve the water purification effect of the sedimentation tank for improving the water resources and land use efficiency in China.In this study, the existing double-layer advection sedimentation tank was improved.Two new inclined plate double layer advection sedimentation tanks are designed: downflow inclined plate double layer advection sedimentation tank (model A), upward flow inclined plate double layer advection sedimentation tank (model BN), and a series double layer advection sedimentation tank.Model C, and three sedimentation tank models were made.Based on the model test and numerical simulation of the flow field in Shihezi area, the conclusion of model test and numerical simulation is analyzed.This paper introduces in detail the design principle of the new inclined plate structure double-layer advection sedimentation tank and the design parameters of the sedimentation tank model, which can provide a reference for the subsequent design and research of the double-layer advection sedimentation tank.Under the same hydraulic conditions, the results of the experiments without flocculant and with flocculant show that the settling effect of model A is better than that of model B and model C.2) during the initial operation of the sedimentation tank without adding flocculant, the settling effect of model A is better than that of model B and model C.The process of water quality stabilization from fresh discharge to outflow is a gradual process. The interval between the initial outflow and the outflow stability of the three double-layer advection sedimentation tanks is about 120 min.Two new types of inclined plates are designed to construct double-layer advection sedimentation tank. After 48 hours of continuous operation in the pretreatment workshop of water plant, the operation condition is good and the effluent quality is stable, which can meet the requirements of the continuous operation of the sedimentation tank in practical engineering.All of them can achieve more ideal removal effect.For high turbidity water, in order to ensure a higher removal rate of solid suspensions, the HRT of model A and model B should be set to 70 min and 80 min respectively in the two-layer advection sedimentation tank.The average turbidity of model A is lower than that of model B and model C, and model A is superior to model B and model C in reducing effluent turbidity.The removal rate of solid suspensions in model A is close to that in model B in the process of steady outflow. After adding flocculant, the removal rate of solid suspensions in three sedimentation tank models is close to that of model B, and the removal rate of solid suspensions in model A is similar to that in model B.The results show that there is no significant correlation between the removal rate of solid suspended solids and the dip angle of the bottom plate of the double-layer advection sedimentation tank.The flow field distribution of double-layer sedimentation tank under different flow rates was simulated by two-dimensional flow field simulation. The flow field distribution diagram of double-layer sedimentation tank was analyzed through the analysis of flow field distribution diagram.It can be concluded that the flow field distribution of model A is more uniform than that of model B and model C.The reflux area and dead water area of model A are smaller than that of model B and model C, and the flow field characteristics of model A are better than that of model B and model C. this conclusion is in agreement with the conclusion of model A, which is better than that of model B and model C.The three double-layer advection sedimentation tanks have a large area of turbulent flow in the inflow zone, which can be solved by reasonably arranging the orifice holes of the flow regulating plate and so on.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU991.23

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