【作者】 张艳；

【导师】 李继；

【作者基本信息】 哈尔滨工业大学 ， 环境工程， 2010， 硕士

【摘要】 紫外消毒技术由于其高效性,广谱性,安全性等特点,在水处理消毒领域应用越来越广泛,相应对紫外消毒设备的研究也越来越多。目前,国外已利用计算流体力学(CFD),采用数值模拟进行紫外设备开发优化;国内生产商主要是模仿国外厂家进行生产,缺乏核心技术,紫外消毒效果无法得到保证。本课题利用CFD数值模拟技术,从光强分布,流态分布以及剂量拟合三个方面建立紫外消毒模型,并采用生物方法对模型进行验证;利用CFD模型对腔体式紫外消毒反应器、明渠式紫外消毒系统进行结构优化及消毒效率预测评估;最后对紫外剂量同步技术进行了初步探究。紫外消毒CFD模型的建立及验证,结果表明:紫外消毒反应器内光强分布不均匀,进出口处光强较弱,随着与灯管距离的增大而降低;反应器内前段,反应器内壁处光强小而流速大,是影响消毒效率的原因;有效剂量随处理流量的增加而降低,呈乘幂关系;有效剂量随透光率的降低而降低,在高流量下受透光率影响不大。模拟结果与实验结果趋势相符,柱源模型误差范围为2.9%~12.0%,线源模型误差范围为5.5~21.4%,柱源模型更精确,可以较准确的计算紫外反应器消毒效率。腔体式紫外反应器的数值模拟,结果表明:基本模型的消毒灭活率1.73个log,t10/HRT为21.0%;挡板的添加有利于流体内部交换,使不同粒子接受的剂量趋于均匀,提高了整体的消毒效率,优化后模型的t10/HRT为59.6%,灭活率为2.02个log。明渠式紫外消毒系统的数值模拟,结果表明:渠道内灯管呈矩阵对称分布,光强在近灯管处最大,近壁面处较小;明渠前段及内壁处光强小而流速大,降低了消毒效率;通过对明渠进行结构的改进,系统内最低光强由由1.3mw/cm2增加至7.2mw/cm2,低剂量(小于20mJ/cm2)的区域消除,高剂量范围内分布更均匀,有利于系统消毒效率的提高。剂量同步主要通过操作参数优化实现:对于结构已定的小型单灯管腔体式紫外消毒反应器,可优化的操作参数主要是停留时间(流量控制);对于复杂的多灯管紫外消毒系统,主要控制参数为灯管有效输出,灯管排布以及流量控制。CFD数值模拟可以精确模拟紫外消毒过程,为紫外消毒设备的设计运行,强化反应器的处理效果提供有利的支持,为系统优化设计和剂量同步提供依据。更多还原

【Abstract】 UV disinfection is used widely in the field of water disinfection because of its high efficiency, broad spectrum and safety features. Accordingly, the people are concerning of UV disinfection equipment much more than before. At present, the domestic producers imitate foreign manufacturers, the main production is lack of core technologies and the disinfection efficiency can not be guaranteed. Computational fluid dynamics (CFD) was used in this research. Based on intensity field, flow field and equivalent reduction dose, established numerical simulation model of UV disinfection. Using bioassay verified the CFD model on the condition of the UVT (80%~95%) and the flow rate (240~600L/h). In addition, optimized the structure of existing UV disinfection reactor and forecasted the disinfection efficiency of channel-type UV system. At last, UV dose of synchronization technology was inquiried preliminarily.The numerical simulation and bioassay showed that: light intensity was uneven in the UV reactor, light intensity was wake at the entrance and decreased with the distance increased from the lamp; the UV intensity was weak while the velocity was large adjacent to the wall near the inlet of the reactor, which affected disinfection efficiency adversely; RED increased with the increase of flow rate and decrease of the transmittance; transmittance had merely a slight impact on RED of high flow; the results showed that the model predicted the disinfection efficiency with good accuracy, RED of simulation and experimental under different conditions had a difference of 2.9~12.0%with cyclinder model while 5.5~21.4% with line model; the cyclinder model could accurately calculate the efficiency of UV disinfection reactor.Optimized the tube UV reactor’s structure, the results showed that: the basic model of disinfection inactivation rate was 1.73log while t10/HRT was 21.0%; baffle added was conducive to the internal fluid exchange, so that the different doses of particles received more uniform and improved the overall disinfection efficiency; the optimized model t10/HRT was 59.6% while inactivation rate was 2.02log.Open channel UV disinfection system’s numerical simulation results showed that: UV lights within the channel was symmetrical, the UV intensity near the lamp was the maximum, near wall was small; the UV intensity was small while velocity was large in front of the channel and the channel wall that reduced the disinfection efficiency; through the open channel structural improvements, the minimum UV intensity increased from 1.3mw/cm2 to 7.2mw/cm2 and low dose (less than 20mJ/cm2) region eliminated while high dose range was more evenly that improved the whole system efficiency.Dose synchronization achieved primarily through the optimization of operation parameters: for the small single lamp chamber reactor, disinfection efficiency depends mainly on water quality and residence time, operating parameters can be optimized primarily was residence time (flow control); For complex multi-lamp UV disinfection system, the main control parameters were effective output of the lamp, the lamp arrangement and flow.CFD numerical simulation can accurately simulate the UV disinfection process, provide support for UV disinfection equipment design and operation, strengthen the treatment effect of UV reactor , provide the basis for system optimization and dose synchronization.更多还原