煤烟气再循环富氧燃烧污染物排放特性研究

Study on Pollutant Emission Characteristics From Oxy-fuel Combustion of Coal With Recycled Flue Gas

基于15kW一维下行燃烧炉，对烟气再循环富氧燃烧和常规空气燃烧2种工况下的污染物排放特性进行对比研究，发现烟气再循环富氧条件下煤粉燃尽率下降4．6％，烟气中CO浓度略有增加，而NOx和SO2的浓度大幅增加，但NOx转化率显著下降；静电低压撞击器（electrical low pressure impactor，ELPI）的测量结果表明，两工况排放颗粒物在1-10m区间都存在2个峰值，但烟气再循环富氧燃烧工况下颗粒双峰向大粒径方向移动。扫描电镜（scanning electron microscope，SEM）结合x-射线能谱（energy dispersive X-ray，EDX）的观测分析发现，颗粒物烟气再循环富氧燃烧工况和空气燃烧工况下PM．o的微观形貌和主要成分基本相同。颗粒物的电感耦合等离子体（inductively coupled plasma，ICP）分析表明，2种工况下PM10中的次量元素和大部分痕量元素分布基本一致，但烟气再循环富氧燃烧工况下PM10中Se的含量要明显高于空气工况，这可能是由于该工况下烟气中水蒸气含量较高，促进了CaO与灰中Se02的反应。

Based on 15 kW one-dimensional download furnace, comparative experimental research on pollutant emissions from flue gas recycled combustion and air combustion were developed. It is found that for flue gas recirculation（FGR） combustion, the burnout rate of coal decreases 4.6%; In the flue gas, CO concentration increases a little, NOx and SO2 concentration in flue gas increased significantly, while the emission rate of NOx decreases. Electrical low pressure impactor（ELPI） measurement shows that there are two peaks in size distributions of PM10 mass concentration of both combustion conditions, but peaks in FGR combustion move to larger particle size. Observations of scanning electron microscope（SEM） and energy dispersive X-ray（EDX） show that PMI0 in both experiments have the similar morphology and components. Analysis of inductively coupled plasma（ICP） show that most minor elements and trace elements distribution in PMI0 from both combustion conditions are similar except Se. Se content in PMt0 from FGR condition is significantly higher than that in air combustion, which might due to the promoted reaction between CaO and SeO2 by high H2O vapor concentration in FGR combustion.