沉降炉实验研究了煤粉O2/CO2燃烧时PM2.5的生成特性和主要成灰元素中危害较大的Fe、S元素生成特性.实验用DT烟煤、NMG褐煤和XLT褐煤,实验温度1300℃,在O2/CO2=1:9,1:4,3:7和O2/N2=1:4气氛下燃烧.低压撞击器(DLPI)按不同粒径大小从0.03～9.8μm共分为13级,分别收集燃烧后的PM10.实验结果表明,O2/CO2燃烧生成的颗粒物均成三模态分布,分别存在于0.15 μm附近、1.58 μm附近和3 μm以上;相比O2/N2,O2/CO2燃烧可有效减少PM2.5的生成,O2/CO2燃烧适当降低氧含量也可有效减少PM2.5的生成;O5/CO2燃烧方式有效地降低了PM2.5中Fe、S元素的生成浓度;Fe、S在PM2.5.中总浓度均较大,超细模态和中间模态颗粒物中S的浓度均较大,中间模态中S的总浓度甚至可能大于超细模态,Fe主要存在于中间模态颗粒物中;不同煤种生成的PM2.5中S的浓度随燃烧方式和氧含量的变化呈现不同的规律.%Laboratory scale experiments were conducted to study the formation and elemental concentration of PM2.5 burning three typical Chinese coals in a drop tube furnace (DTF). The reaction temperature was 1300℃ .The combustion atmosphere was O2/CO2 and O2/N2. The oxygen content in the O2/CO2 combustion was 10％, 20％ and 30％, respectively, the combustion in O2/N2 mixture of 1: 4 was also performed for a comparison. PM10 was collected with a 13 stage low-pressure impactor (LPI) having an aerodynamic cutoff diameter ranging from 0.03 μm to 9.8 μm. The experimental results indicate that the tri-modally distribution are observed in the O2/CO2 combustion around 0. 15 μm, 1.58 μm and larger than 3 μm. In comparison with the O2/N2 combustion, the O2/CO2 combustion can be effective in reducing PM2.5 formation. Besides, decreasing the oxygen content causes a reduction of PM2.5. Iron and sulfur have the quite adverse health effects comparing with other dominating elements in the particulate matter, so their concentration in PM2. 5 is non-ignorable. The sulfur concentration in the central mode of PM2. 5 is slightly less or even larger than the sulfur concentration in the ultrafine mode, and iron mostly exists in the central mode of PM2. 5. As the combustion condition changes, the sulfur concentration in PM2.5 from different coals presents a different characteristic.
展开▼
