Development Of UV Disinfection Model And Equipment Optimization

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.