二恶英发生源的建立及其性能分析

Establishment of a dioxin generating system and its performance analysis

针对如何在臭氧紫外光-滑动弧系统中建立稳定的二恶英发生源用于降解二恶英的实验系统.该发生源以医疗垃圾飞灰为对象,通过加热飞灰本身和飞灰索提液的方式使其中的二恶英在一段时间内连续挥发.结果表明,290℃时在飞灰发生源系统中,二恶英初始阶段挥发速率极快,后续的挥发速率急剧减小并趋于稳定,总挥发量仅为总量的10%,且难以再提高.相比而言索提液发生源系统挥发出的二恶英更多更稳定,但其挥发量受温度和注射速度的影响较大:当注射速度为1μL.min-1时,在300℃、400℃、500℃三个不同温度段分别为2.78%、7.88%和9.56%;当温度为500℃,注射速度为0.2 mL.min-1时,其挥发率提高到48.7%.研究还发现,注射针头与管壁的残余量是影响挥发效率的两个重要因素,当温度为500℃,载气为1000 mL.min-1,注射速度为0.2 mL.min-1时,连续进样1 h后,两者的残余量分别占注射总量的40.0%和16.7%.

A stable dioxin generating system has been constructed for the O3/UV/Gliding Arc system,and this system could be used to degrade PCDD/Fs.The medical waste fly ash was investigated as a material of the dioxin generating system.By heating fly ash or PCDD/Fs stock solution,dioxins evaporated.The results indicate that fly ash（1.0 g） is heated in oil at 290 ℃,at first 15 min PCDD/Fs generated very fast,after 15 min the speed of generating slow down and become stable,but only 10% PCDD/Fs is generated,but it is hard to enhance.Compared with fly ash heating by oil,PCDD/Fs stock solution evaporating is better.It can generate more PCDD/Fs and is more stable.Temperature and feeding flow rate influence PCDD/Fs evaporation.When feeding flow rate is 1 μL·min-1,at 300 ℃,400 ℃,500 ℃,PCDD/Fs can evaporate 2.78%,7.88% and 9.56%.At 500 ℃,when feeding flow rate is 0.2 mL·min-1,PCDD/Fs can evaporate 48.7%.The results also indicate that,remains contained in inject and in tube also influence the generating of PCDD/Fs.When tube is heated at 500 ℃,N2 gas flow rate is 1 000 mL·min-1,feeding flow rate is 0.2 mL/min,solution evaporate 1 h,40% and 16.7% PCDD/Fs is in inject and tube.