煤粉热解过程对PM_(0.1)内元素成分的影响

Influence of Pyrolysis Process on Elemental Distribution of PM_(0.1) from Coal Combustion

选取典型烟煤(PDS)及其分离出的含有机结合态金属较多的中密度(MD)煤样,在沉降炉中进行煤粉热解和燃烧收取颗粒物的试验,研究了热解过程中释放的有机结合态金属对典型烟煤燃烧生成的PM0.1中元素成分的影响.结果表明:1.5μm以下热解颗粒中无机元素成分分布与燃烧生成的PM0.1中元素较接近,显示出有机结合态金属分解对PM0.1的贡献;SEM-EDS分析表明,热解颗粒主要由碳质和挥发性金属组成,粒径略大时,挥发性金属含量降低;PDS原煤与其MD煤样相比,Ca、Fe在其内在矿和外在矿的分布形式和含量的不同导致了其在热解颗粒和PM0.1中含量不同;对于含有机结合态金属较多的MD煤样,在温度较低时,PM0.1多由有机结合态金属分解、气化生成,在温度较高时,难熔元素的气化对PM0.1的贡献有所增加.

Experimental tests were carried out with particles taken from pyrolysis and combustion of typical bituminous（PDS） coal and its separated medium density（MD） coal containing abundant organically bound metals in a drop tube furnace,so as to study how the organically bound metals released from pyrolysis process effect the elemental distribution of PM0.1 from combustion of PDS coal.Results show that the inorganic elemental composition of particles smaller than 1.5 μm generated from coal pyrolysis is almost same as that of PM0.1 from coal combustion,which presents the contribution of decomposition and vaporization of organically bound metals to the formation of PM0.1.SEM-EDS analysis indicates that the pyrolysis particles mainly consist of carbonaceous and volatile metals,as the particle size increases,the content of volatile metals decreases.The content and distribution difference of Ca Fe in included and excluded minerals between MD and PDS coal causes the content distinction of Ca Fe in pyrolysis particles and PM0.1.For the MD coal containing rich organically bound metals,if the temperature of coal combustion is relatively low,the subsequently generated PM0.1 will mainly come from the decomposition and vaporization of volatile organically bound metals,and if the temperature of coal combustion is relatively high,the vaporization of refractory organically bound metals will play a role in PM0.1 formation.