机械絮凝斜管沉淀池沉淀区数值模拟与试验研究

发布时间：2018-01-09 01:28

本文关键词：机械絮凝斜管沉淀池沉淀区数值模拟与试验研究　出处：《扬州大学》2014年硕士论文　论文类型：学位论文

【摘要】：高密度沉淀净水工艺是集絮凝、沉淀、污泥浓缩于一体的新型水处理技术,具有占地面积小,处理效率高的优点,已得到广泛应用。目前,国内采用高效沉淀池工艺的水厂有50多座,总供水量超过1500万m3/d,已建项目大多是借鉴了国外高密度沉淀池的形式,并在参考机械搅拌絮凝和斜管沉淀工艺经验基础上开展设计的,国家没有相应的设计规范。沉淀池的结构设计更多是满足工艺流程需要,在絮凝和沉淀水力条件上考虑较少。本文以扬州市第一水厂改扩建工程中采用的机械絮凝斜管沉淀池为对象,采用数值模拟和中试研究相结合的方法,对沉淀池的颗粒浓度和流场进行模拟,提出了优化设计的改进措施,中试研究明确了各项运行参数。主要得出以下结论： (1)通过对沉淀区污泥颗粒浓度场的数值模拟,结果表明最佳颗粒密度为1050kg/m3,过高的颗粒密度会加剧异重流现象,过小则影响沉淀效率。 (2)对不同进水口高度以及在沉淀区前增设配水槽效果进行模拟。在保持沉淀区进水口宽度不变,当进水口高度为1.2m,即进水速度为0.024m/s时,流场分布更加均匀；在沉淀区前增设配水槽,可使进水沿池宽方向分布均匀,提高了水流稳定性,更有利于颗粒沉降和污泥浓缩。 (3)研发了水量为2000m3/d的中试装置,通过烧杯实验和中试试验,对混凝剂投加量、助凝剂投加量、污泥回流比等控制参数进行了优化试验,探索针对第一水厂原水条件下的最佳运行参数。结果表明,当PAC投加30mg/L、PAM投加0.1mg/L、污泥回流比为4%时,沉淀池出水水质最好,出水浊度基本都低于1NTU；在机械絮凝斜管沉淀池连续稳定运行一段时间后,可以适当降低混凝剂投加量至20-25mg/L,出水仍可达到预期效果。
[Abstract]:High density sedimentation water purification process is flocculation, sedimentation, sludge concentration in one of the new water treatment technology, has the advantages of small occupied area, with the advantages of high efficiency, has been widely used. At present, the domestic process of efficient sedimentation tank water has more than 50, the total amount of water is more than 15 million m3/d, the project has been built mostly draw lessons from the foreign high density sedimentation tank, and carry out design reference in mechanical mixing flocculation and sedimentation process of inclined pipe on the basis of the experience, countries do not have the corresponding design specification. The structure design of the sedimentation tank is more to meet the needs of process flow, less consideration. In the hydraulic conditions on flocculation and sedimentation
In this paper, the first water plant in Yangzhou city changed the mechanical flocculation inclined tube sedimentation tank in the expansion project as the object, using the research method of combining numerical simulation and, on particle concentration and flow sedimentation tank is simulated, the improvement measures are put forward to optimize the design of the pilot study, clear the main draw operation parameters. The following conclusions:
(1) based on the numerical concentration of granular sludge precipitation field simulation, the results show that the optimal particle density is 1050kg/m3, the high density of particles will exacerbate the current phenomenon, is a small influence on the precipitation efficiency.
(2) of different inlet height and the settling zone is added before the sink with simulating the effect. In the settling zone inlet width is constant, when the inlet height is 1.2m, the inlet velocity is 0.024m/s, the flow field distribution is more uniform; additional distributing water trough in the precipitation area, can make the uniform water distribution along the width direction, improve the flow stability, more conducive to the particle settling and sludge concentration.
(3) the research content is 2000m3/d in pilot plant by beaker experiment and pilot test of coagulant dosage, coagulant dosage, the sludge reflux optimized control parameters such as ratio of exploring the best operating parameters for the first raw water conditions. The results show that when the dosage of PAC 30mg/L PAM, the dosage of 0.1mg/L, sludge return ratio is 4%, the sedimentation tank effluent, the effluent turbidity was lower than that of 1NTU; the sedimentation tank is continuous and stable operation for a period of time in mechanical flocculation inclined tube, can reduce the dosage of the coagulant to 20-25mg/L, effluent can reach the expected effect.

【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU991.2

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