O_2/CO_2气氛添加高岭石对燃煤PM_(2.5)排放的影响

采用管式炉研究了在O2/CO2气氛下添加高岭石对PM2.5(空气动力学直径小于2.5μm的颗粒物)排放特性的影响。实验采用荷电低压撞击器(ELPI)采集和分析燃烧后的PM2.5。结果表明,添加高岭石是燃烧过程中影响PM2.5生成的重要因素。添加高岭石后,生成PM1的数量和质量浓度均降低,而PM1-2.5的数量和质量浓度均略有增加,PM2.5粒径分布均呈双峰分布,峰值点分别出现在0.2μm和2.0μm左右。随着高岭石添加质量比的增加,PM2.5中的S、Pb、Cu、Na和K五种元素的浓度呈下降趋势。粒径小于0.317μm的亚微米颗粒通过气化-凝结机理形成,而超微米颗粒则是通过亚微米颗粒凝聚、聚结和矿物质熔融、破碎、聚结形成。

Effect of kaolinite additive on formation of PM2.5 under O2/CO2 atmosphere during coal combustion

The influence of kaolinite additive on the emission characteristics of PM_2.5 (particulates with aerodynamic diameter less than 2.5μm) was studied with a tube furnace. The combustion tests were carried out at 1123K under O₂/CO₂ atmosphere. The PM_2.5 generated from coal combustion was collected and analyzed with an Electrical Low Pressure Impactor (ELPI). The results indicate that kaolinite is an important factor for the formation of PM_2.5 during coal combustion under O₂/CO₂ atmosphere. The number and mass concentrations of PM₁ diminish, but those of PM_1~2.5 enhance slightly after kaolinite is added. The size distributions of PM_2.5are similar, which display two peaks around 0.2μm and 2.0μm, respectively. With increasing the weight ratio of kaolinite, the concentrations of S, Pb, Cu, Na and K decrease. The submicron-size ash particles smaller than 0.317μm are formed via nucleation of vaporized ash components. The supermicron-size ash particles are formed by coagulation and coalescence of the submicron-size ash, and fragmentation and coalescence of mineral matter.