基于CFD的饮用水臭氧消毒装置的设计及优化

发布时间：2019-06-14 15:36

【摘要】：目前,我国无论是城镇还是农村,水资源都存在着较大的安全隐患。农村的用水中只有13.8%是符合国家饮用水标准。在城镇,年久失修的供水管网以及难以保证卫生安全的二次供水系统,也导致自来水在到达用户家中时不能达到标准,同时也导致了我国的直饮水计划难以推行。论文中设计的臭氧水消毒装置能解决上述的自来水的二次污染的问题。装置以臭氧为消毒载体,包括四大部分,分别是：臭氧的制备、臭氧向水中的传质、臭氧水与自来水的反应、尾气的处理。在用臭氧处理水时,随着水质的变化及水处理量的变化,臭氧的投加量及处理时间也会发生变化,整套装置的设计也会发生变更。初将水处理量定为40L/min,查找行业相关参数,结合水质的情况,可将水中臭氧的反应浓度定为2mg/L,反应时间定为10min。根据以上参数,计算选择臭氧发生器的类型及产量,臭氧水混合泵的型号,反应器的有效容积,以及各管路的公称直径及材料。确定装置采用间接供气的反应方式及连续的工作模式。间接供气的反应方式通过臭氧水混合泵吸收臭氧,然后利用产出的臭氧水与待反应水反应。由于本装置尾气量并不像直接供气反应器那么大,所以采用分子筛或硅胶吸附的方法去除多余尾气中的臭氧。臭氧的消毒效率是利用CT值来评价的。C表示臭氧在水中的浓度,T表示臭氧在水中的停留时间,CT值越大则消毒效果越好,而过大的C值可能产生超标的DBPs。而在实际应用中也使用CT1o来代替CT计算臭氧的消毒效率。臭氧水与待反应水是在反应器中接触并反应的,论文中希望能通过合理的设计优化反应内的结构,改善臭氧在水中的停留时间分布,使得能在较低的臭氧浓度的情况下取得较高臭氧的消毒效率。文中将臭氧水反应器分为两个功能区,即推流区和混合区。推流区中以推流为主要流态,推流是通过减小跨距的设计来实现的,臭氧水是在推流区中注入反应器。推流的流态能使流经该区域的水的停留时间相差不多,从而与臭氧接触的时间也较为均衡,不至于形成部分水流过度臭氧化而浪费臭氧。所设计的混合区中以涡流的流态为主,涡流是通过增加区域的跨距以及布置导流板来实现的,涡流能降低臭氧的浓度梯度,使臭氧浓度分布更均匀,利于提高臭氧的利用率。设计的臭氧水反应器共有9个区域。C1-C4区属于功能区1,其中流态以推流为主；C5-C9区属于功能区2,其中的流态以涡流为主。在分析内部的流体状态时,使用了计算流体力学(CFD)以及Gambit和Fluent软件。建立了反应器的物理模型,并进行了数值计算。根据数值计算的结果得出了如下结论： (1)C1-C4区以推流流态为主,但是有较严重的短流现象,导致了水流在该区域内的停留时间分布不均。 (2)C5-C9区中的涡流流态不明显,也存在较为严重的短流现象。根据数值计算的结果,分别提出了两种优化方案,方案一和方案二。对方案一和方案二建立物理模型和数值计算,得出如下结论： (1)方案一中C5-C9区中导流板的布置相比方案二要合理,能较好的促进涡流的产生及合理分布。 (2)方案二中C1-C4区导流板的布置以及隔板的尺寸设计较方案一得到了较优的结果。 (3)在以上方案分析的基础上提出了更为合理的优化方案：反应器的C1-C4区,采用方案二的优化方式；反应器的C5-C9区采用方案一的优化方式。结合两种方案的优点,使得反应器内的水流状态更加符合设计要求。
[Abstract]:At present, there are great potential safety hazards in both urban and rural areas. Only 13.8 per cent of the rural water is in line with the national drinking water standards. The secondary water supply system, which is difficult to guarantee the sanitation and safety, can not reach the standard when it reaches the user's home, and the direct drinking water plan of our country is hard to implement. The ozone water disinfection device designed in the paper can solve the problem of secondary pollution of the running water. The device uses ozone as a disinfection carrier, which comprises four parts, namely, the preparation of ozone, the mass transfer of the ozone into the water, the reaction of the ozone water and the tap water, and the tail gas In the process of treating water with ozone, with the change of water quality and water treatment capacity, the dosage of ozone and the treatment time will also change, and the design of the whole set of devices will change. At the beginning, the water treatment capacity is set to 40 L/ min, the relevant parameters of the industry are found, the reaction concentration of the ozone in the water can be set to 2 mg/ L, and the reaction time is set to 10 mi in combination with the water quality. N. According to the above parameters, calculate the type and yield of the selected ozone generator, the model of the ozone water mixing pump, the effective volume of the reactor, and the nominal diameter and the material of each pipeline. Material. Determination device adopts indirect gas supply reaction mode and continuous working mode and the ozone is absorbed by the ozone water mixing pump in a reaction mode of indirect air supply, and then the generated ozone water and the water to be reacted due to the fact that the tail gas quantity of the device is not as large as the direct gas supply reactor, the odor of the excess tail gas is removed by adopting a molecular sieve or a silica gel adsorption method, The efficiency of the disinfection of ozone is to use the CT value . C indicates the concentration of ozone in water, T represents the residence time of the ozone in water, the higher the CT value, the better the disinfection effect, and the too large C value may result in a superscalar D. BPs. CT1o is also used in practical applications instead of CT to calculate ozone The ozone water and the water to be reacted are contacted and reacted in a reactor, and in the paper, it is desirable to optimize the structure in the reaction through a reasonable design, to improve the residence time distribution of the ozone in the water, so that the elimination of the higher ozone can be achieved in the case of lower ozone concentration. In this paper, the ozone water reactor is divided into two functional areas, namely, the flow-pushing area and the flow-off area. In that flow area, the push-flow is the main flow state, the push-flow is realized by reducing the design of the span, and the ozone wat is injected in the flow-out area. the flow pattern of the push-flow can make the residence time of the water flowing through the area to be similar, so that the time of contact with the ozone is also balanced, so that the part of the water flow is not over-ozonated and the wave is not formed, the vortex flow is mainly realized by increasing the span of the region and arranging the guide plate, so that the concentration gradient of the ozone can be reduced, the distribution of the ozone concentration is more uniform, the utilization ratio of the designed ozone water reactor There are 9 areas. The C1-C4 area belongs to the functional area 1, where the flow state is the main flow, and the C5-C9 area belongs to the functional area 2, where the flow pattern The computational fluid dynamics (CFD) and Gamit and Flu are used in the analysis of the fluid state in the interior. The physical model of the reactor is established, and the physical model of the reactor is established. The numerical calculation is based on the results of the numerical calculation. The following conclusions are as follows: (1) The C1-C4 region is dominated by the push-flow state, but there is a serious short-flow phenomenon, which leads to the stop of the water flow in the region. The residual time distribution is not uniform. (2) The vortex flow pattern in the C5-C9 region is not obvious, and it also exists. In this paper, two kinds of excellent short-flow phenomena are put forward according to the result of the numerical calculation. (b) The establishment of a physical model for programme I and II, as well as in programme I and II. The numerical calculation results in the following conclusion: (1) The arrangement of the guide plate in the C5-C9 area of the scheme is reasonable and can be better than that of the scheme 2. to promote the generation and reasonable distribution of the vortex, (2) the arrangement of the guide plate in the C1-C4 region of the scheme II and the ruler of the partition plate, (3) A more reasonable optimization scheme is put forward on the basis of the above scheme analysis: the C1-C4 area of the reactor and the optimization method of the scheme II are adopted; and the reactor The C5-C9 region of the invention adopts the optimization mode of the scheme I. The advantages of the two schemes are combined,
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R123.1

【参考文献】