气煤分选组分的结构差异及其对高硫煤热解硫变迁的影响

Structural difference of gas coal separation components and its effect on sulfur transformation during pyrolysis of high sulfur coal

利用ZnCl2溶液将两种气煤分别分选为不同镜质组含量的四种组分,通过核磁共振波谱(^(13)C NMR)、煤岩分析仪、X射线荧光光谱(XRF)和基氏流动仪等表征分析了分选组分的炭结构、显微岩相组成、灰成分和胶质体行为,结合X射线光电子能谱仪(XPS)探讨了不同气煤分选组分对高硫煤硫分热变迁行为及焦炭中形态硫分布的影响。结果表明,随着气煤中镜质组含量的增加,脂肪碳比例增大,热解过程中挥发分释放量增多,其中的氢自由基促进了形态硫的分解且及时稳定生成的硫自由基,形成含硫气体释放,使焦中硫含量降低;气煤中低密度组分的最大流动度最大、塑性区间最宽,与高硫煤共热解过程中胶质体稳定性最好;气煤中碱性矿物质主要富集在高密度组分中,导致共热解焦中硫化物硫和硫酸盐硫增加;共热解过程中,富集气煤中镜质组和选用碱性矿物质易脱除的煤种有利于焦中硫分的降低。

Two gas coals were respectively separated into four components with different vitrinite content using ZnCl2 solution.The carbon structure,composition of coal macerals and minerals,and plastic layer behavior of separating components were characterized by nuclear magnetic resonance spectrometer(^(13)C NMR),coal rock analyzer,X-ray fluorescence spectrometry(XRF)and Gieseler fluidity.Combining with X-ray photoelectron spectroscopy(XPS),effect of different gas coal separation components on sulfur transformation behavior during pyrolysis of high-sulfur coal and distribution of sulfur forms in coke was investigated.The results show that with increase of vitrinite content in gas coal,the relative ratio of aliphatic carbon in coal increases,and the release amount of volatiles increases during pyrolysis;hydrogen free radicals in volatiles promote decomposition of sulfur,stabilize sulfur free radicals in time and release as sulfur-containing gases,and thus sulfur content in coke is reduced.Low density components in gas coal have the largest maximum fluidity and widest plastic range,and stability of plastic layer is the best during co-pyrolysis with high sulfur coal.The basic minerals in gas coal are mainly enriched in high density components,which leads to increase of sulfide sulfur and sulfate sulfur in the coke.For utilization of gas coal in coal-blending pyrolysis,enrichment of vitrinite and selection of coals with easier removal of alkaline minerals are beneficial for reducing sulfur in coke.