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采用管式炉和荷电低压撞击器(electrical low pressure-impactor,ELPI)研究了4种煤粉在O2/CO2条件下燃烧后生成的PM2.5排放特性,并对空气和O2/CO2气氛下PM2.5的排放特性进行了比较。结果表明:不同煤粉在O2/CO2气氛下燃烧后,所产生的PM2.5质量浓度均呈双峰分布,峰值分别在0.1和2μm左右;S在亚微米颗粒上明显富集,而在超微米颗粒上含量相对较少;K和Na在亚微米颗粒上含量比在超微米颗粒上高一些;Si和Ca在亚微米颗粒上含量相对较少,而在超微米颗粒上含量相对较多;Fe在亚微米和超微米颗粒上含量相当。分析认为,不同煤粉中组分形式和含量的不同,影响了煤粉燃烧后PM2.5形成的过程,造成PM2.5排放特性的不同。从PM2.5的粒径分布、元素分布和形貌分析可知,和空气气氛相比,O2/CO2气氛不影响PM2.5的生成机制,但影响其粒径分布。
PM2.5 emission characteristics of four kinds of pulverized coal after combustion under O2 / CO2 conditions were studied by using tubular furnace and electrical low pressure-impactor (ELPI), and the effects of air and O2 / CO2 atmosphere PM2.5 emission characteristics were compared. The results showed that the mass concentration of PM2.5 produced by different pulverized coal combustion in O2 / CO2 atmosphere showed a bimodal distribution with peak values of about 0.1 and 2 μm, respectively; S was obviously enriched in submicron particles, The contents of K and Na on the submicron particles are higher than those on the ultrafine particles. The content of Si and Ca on the submicron particles is relatively less, while that on the ultrafine particles is relatively higher. Fe is equivalent in submicron and supermicron particles. The analysis shows that the composition and content of different pulverized coal affect the formation process of PM2.5 after pulverized coal combustion, resulting in different PM2.5 emission characteristics. According to the particle size distribution, elemental distribution and morphology analysis of PM2.5, the O2 / CO2 atmosphere does not affect the formation mechanism of PM2.5, but affects the particle size distribution.