民用蜂窝煤燃烧排放颗粒物的化学组成和稳定碳同位素特征

摘要

本文选用了镜质组反射率在0.77%~1.88%之间5种不同成熟度的煤,将其制成民用蜂窝煤球,研究民用蜂窝煤燃烧排放颗粒物(PM)的化学组成,包括元素(C、N、O、S)、有机碳(OC)、元素碳(EC)和水溶性无机离子(WSII),稳定碳同位素组成特征和质量吸收效率值(MAE),并讨论了它们与煤成熟度之间的关系。结果表明,5种原煤C、N、O、S元素组成差别不大,但是燃烧后排放的PM化学组成差别比较大。无烟煤燃烧排放的PM粒径分布呈双峰结构,峰值分别在0.09µm 和0.25µm；而烟煤PM的峰值为0.58µm。无烟煤排放PM的颗粒数远小于烟煤。PM、OC和EC的排放受煤成熟度的影响非常大,无烟煤排放的量最小,分别为2.21 g/kg、0.22 g/kg和0.004 g/kg；成熟度最低的烟煤排放量最大,分别为70.3 g/kg 、46.1 g/kg和2.42 g/kg。PM、OC和EC的排放因子与煤的成熟度成幂指数关系。EC的MAE在0.17~21.9 m2/g之间,与煤成熟度呈指数相关关系。燃煤 WSII 的平均排放因子为801 mg/kg, WSII 当中含量最高的是4NH和24SO ,平均分别占 WSII总量的23.5%和44.4%。燃煤排放PM的δ13C变化范围为–24.5‰~–22.8‰,平均值为–23.6‰。以上研究有助于人们从原煤性质的角度去考察民用燃煤对人类健康和气候变化的影响,并为大气污染源解析提供一些科学依据。%In this study, 5 coals with different vitrinite reflectance (Ro = 0.77%~1.88%) were selected, powdered and made into honeycomb coal briquettes. The emission factors of particulate matter (PM) including elements (C, N, O, S), organic carbon (OC), elemental carbon (EC) and water soluble inorganic ion (WSII) and the mass absorption efficiency (MAE) of EC were determined. The relationship between chemical composition and geological maturity were discussed. The results show that the raw coals with similar elementary composition may yield emissions with different chemical composition. There were two peaks of size distribution of PM from anthracite which was at 0.09 µm and 0.25 µm, respectively, while the peak of size distribution of PM from bituminous coal was at 0.58 µm. The number of PM from the anthracite was much lower than that from bituminous coal. The emission of PM, OC and EC has a power exponent dependence on the geological maturity. The emission of PM, OC and EC was 2.21 g/kg, 0.22 g/kg and 0.004 g/kg for anthracite with the highest geological maturity, and 70.3 g/kg, 46.1 g/kg and 2.42 g/kg for bituminous coal with the lowest geological maturity. MAE of EC from coal combustion was in the range of 0.17~21.9 m2/g. The average emission factor of WSII was 801 mg/kg, and 4NH and 24SO  were the most abundant, accounting for 23.5%and 44.4%of total WSII. Stable carbon isotope (δ13C) of PM emitted from the coal combustion was in the range of–24.5‰~–22.8‰and their average value was–23.6‰. The results in this study would be helpful to understanding the impacts of coal combustion on human health and the climate, and could be used in the source apportion of PM in the atmosphere.