Effect of oxygen concentration on PM2.5 formation during coal combustion under O2/CO2 atmosphere
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摘要: 采用管式炉和荷电低压撞击器(electrical low pressure-impactor,ELPI)研究了徐州烟煤在O2/CO2条件下燃烧后生成的PM2.5排放特性。结果表明,在O2/CO2气氛下,煤粉在不同O2浓度燃烧所产生的PM2.5质量浓度均呈双峰分布,峰值分别在0.1和2.0 mm左右;随着氧含量的增加,PM2.5的质量浓度增加;S、K和Na在亚微米颗粒上明显富集,而Si和Ca未在亚微米颗粒上富集;通过对颗粒物的粒径分布、元素分析和形貌观察,认为亚微米颗粒主要是矿物质蒸发鄄凝结机制形成的,而超微米颗粒主要是煤焦与外部矿物质的破碎以及内在矿物质聚合形成的。Abstract: Pulverized coals were burned in a tube furnace under O2/CO2 atmosphere, and an electrical low pressure-impactor (ELPI) was used to collect the PM2.5. The results show that a bimodal distribution of PM2.5 appears, which is located at 0.1 μm and 2.0 μm, respectively. The mass concentrations of PM2.5 increase with5 enhancing the O2 concentraion. The enrichment of S, Na and K on the sub-micron particles is observed, but that of Si and Ca is not observed. It is proposed that sub-micron particles are formed via the mechanism of vaporization and condensation, and the super-micron particles are formed by the fragmentation of coal char and the coalescence of inherent mineral matter based on the analyses of particle size distribution, elements distribution and morphology of PM2.5.
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Key words:
- O2/CO2 /
- coal combustion /
- PM2.5 /
- formation mechanism /
- O2 concentration
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