市政污泥焚烧过程中温室气体N_(2)O排放特性研究

Study on GHG N_(2)O emission characteristics during municipal sewage sludge combustion process

采用水平管式炉对上海城镇污水处理厂污泥进行燃烧试验。主要开展了燃烧温度、污泥中N含量以及污泥粒径对污泥燃烧过程中N_(2)O的排放特性研究。试验结果表明,温度是影响N_(2)O和NO排放的最重要的因素,随着焚烧温度的升高(750~950℃),燃烧反应更加剧烈,烟气中N_(2)O的排放下降,而NO的排放量上升,高温会促进N_(2)O的自分解和NO的形成;但当温度继续上升到1000℃,N_(2)O的排放量有所升高,NO的排放量有所下降。X射线电子能谱(XPS)分析表明,城镇污水处理厂污泥中蛋白质N和季铵盐N的比例基本维持在70%和30%,基本不随污泥中N含量的变化而变化,不同N含量污泥中燃料N向N_(2)O转化的比例相似。在粒径为1.25 mm时N_(2)O和NO排放较高,而粒径在2.5~4 mm之间N_(2)O和NO排放较低。污泥中燃料N向N_(2)O和NO的转化率之和维持在10%以下。

A horizontal tube furnace was used to conduct combustion experiments on Shanghai sewage sludge.This study mainly investigated the effects of combustion temperature,N content in sludge and sludge particle size on the emission characteristics of N_(2)O and NO during the sludge combustion process.Experimental results show that temperature was the most important factor affecting N_(2)O and NO emissions.As the incineration temperature increases(750~950℃),the combustion reaction became more intense,the N_(2)O emissions in the flue gas decreased,and the NO emissions increased,high temperature would promote the self-decomposition of N_(2)O and the formation of NO.When the temperature rose to 1000℃,the emission of N_(2)O increased and the emission of NO decreased.X-ray electron spectroscopy(XPS)analysis shows that the proportions of protein-N and quaternary-N in municipal sludge were basically maintained at 70%and 30%,and basically did not change with the change of the N content in the sludge.The conversion ratio of fuel N to N_(2)O in sludge with different N contents is similar.N_(2)O and NO emissions were higher when the particle size was 1.25 mm,while N_(2)O and NO emissions were lower when the particle size was between 2.5 mm and 4 mm.The sum of the conversion rates of fuel N to N_(2)O and NO in the sludge was maintained below 10%.