O (sub) 3 Oxidation Column Reactor

Ozone oxidation process is widely used in water treatment engineering. But it is dissolved gas, the waste water treatment effect is restricted by the mass transfer efficiency, so enhance the mass transfer efficiency is the key to strengthen the effect of ozone oxidation.In thesis, the ozonation bubble column reactor acts as the research object. Based on the impact of behavioral factors such as superficial gas velocity, initial bubble diameter, bubble level, through numerical simulation of air bubble within the reactor under different conditions formation and change characteristics, the method was been put forward to strengthen mass transfer. The results show that:(1) Column reactor, ozone gas superficial velocity increased from μobs=8cm/min to72cm/min, removal of drilling and phenol wastewater CODCr reduced by26.7%and13.8%. Under μobs=24cm/min, the CODCr removement of drilling and phenol wastewater are3.9%and10%. Column reactor liquid level rise from75cm to2m, drilling and phenol wastewater CODCr removal rate increased by7.14%and34.19%.Under microporous aeration conditions, ozone gas HRT was related to colunm height:t=0.0844H+7.3986. The decomposition rate of ozone is0.859mg/(L·min).(2) Behavior of ozone gas in the reactor was been simulated by using the Fluent software:①Initial bubble diameter is1.9mm, superficial gas velocity are μobs=8cm/min and24cm/min,the bubble diameter in the reactor is less than4mm; when μobs=40cm/min, the bubble reached coalescence/broken balance at column height of1m, and the size of bubble is around7mm; when superficial gas velocity μobs≥56cm/min, the bubble reached balance when h=0.5m, and the bubble diameter maintained11mm.②When superficial gas velocity μobs=8～40cm/min, the bubble velocity distribution between0.3-0.4m/s; superficial gas velocity μobs=56～72cm/min, the bubble velocity distribution in the0.3-0.7m/s.③When the initial bubble diameter of1.2mm,3.0mm,7.5mm, the superficial gas velocity μobs=24cm/min and56cm/min,when reached coalescence/broken balance, the diameter of bubble are2.3mm,3.5mm,7.8mm and8.6mm,7.6mm,9.7mm.④When the initial bubble diameter are1.2mm,3.0mm and7.5mm, the superficia gas velocity μobs=24cm/min, the speed of escape from the aeration head was0.15m/s,0.30m/s,0.47m/s.⑤In the ozone oxidation column reactors, bubble diameter and speed performance as a center peak type distribution. The reactor diameter are4cm,7cm,13cm, under superficial velocity μobs=24cm/min, initial bubble diameter is1.9mm, the center of the bubble diameter are3.8mm,3.0mm,2.5mm. Bubble velocity of0.4m/s,0.34m/s,0.29m/s.(3) Based on numerical simulation study, Stirring broken method was been put forward to strengthening the gas, liquid mass transfer efficiency.Phenol wastewater was treatment by ozonation superficial gas velocity μobs=8cm/min,40cm/min,72cm/min,without stirring, CODCr removal rate was57.9%,51%,48.5%.When the stirring speed n=200r/min, the phenol wastewater CODCr removal rate reached58.6%,58.1%,57%; when the stirring speed n=500r/min, the phenol wastewater CODCr removal rate dropped to42%.The fluid state in the reactor was observed under superficial gas velocity μobs=40cm/min:When the stirring speed n=100r/min, the bubble diameter is small and distribution of uniform inside reactor; when n=200r/min, bubbles are fully broken and cavitation was generated near stirring rod and blade; when n=500r/min, the gas-liquid cyclone appeared the center of the reactor.(4) The optimum process conditions was put forward based on the numerical simulation:the superficial gas velocity μobs=40cm/min, stirring speed n=200r/min. the bubble coalescence/broken balance reached under the condition of the liquid column height1m, the CODCr removal rate of phenol wastewater up to58.6%.