A CCSEM study on the transformation of included and excluded minerals during coal devolatilization and char combustion
A CCSEM study on the transformation of included and excluded minerals during coal devolatilization and char combustion
复制标题
煤脱挥和焦炭燃烧过程中包含和排除矿物转化的 CCSEM 研究
DOI：
10.1016/j.fuel.2016.01.005
复制
发表时间：
2016
期刊：
影响因子：
7.4
通讯作者：
Xu Minghou
中科院分区：
文献类型：
--
作者：
Wen Chang;Gao Xiangpeng;Xu Minghou
研究了煤的挥发分和焦炭燃烧过程中包裹体矿物和非包裹体矿物的转化途径。将YQ无烟煤、DT烟煤和CF褐煤三种不同煤级的煤种缩小到45−100gμm，在氮气中脱出，并在1300℃的空气中燃烧，利用实验室规模的落管炉制备焦炭和灰烬。用计算机控制的扫描电子显微镜(CCSEM)分析了煤及其衍生的焦炭和灰烬的矿物性质。结果表明，在煤的挥发分过程中，三种煤中的石英和高岭石基本稳定，但富铁矿物(黄铁矿、菱铁矿)和富钙矿物(方解石、铁白铁矿)在挥发分过程中分解，部分中间产物与铝硅酸盐结合。在焦炭燃烧过程中，石英参与燃烧反应，形成铝硅酸盐。而YQ和DT焦中的类莫来石相变化不大，而CF焦中的类莫来石相吸附了富Fe/Ca的细小颗粒，并结合到Fe-Ca-Al-硅酸盐中。大多数富Ca/Fe中间产物与铝硅酸盐反应生成Fe-、Ca-和Fe-Ca-铝硅酸盐。还观察到富Fe/Ca矿物与铝硅酸盐之间的相互作用。YQ无烟煤和CF褐煤富钙矿物中的钙和富铁矿物中的铁在煤的挥发分和半焦燃烧过程中都与铝硅酸盐相互作用。而对于DT烟煤，富钙矿物与铝硅酸盐之间的这种相互作用只在脱挥发过程中发生。此外，还观察到了煤的挥发分过程中，排出的富铁、钙矿物与包裹体的铝硅酸盐之间的相互作用。
This study reports the transformation pathways of both included and excluded minerals during coal devolatilization and char combustion. Three Chinese coals of various ranks, namely YQ anthracite, DT bituminous coal and CF lignite, were size narrowed to 45−100 μm, devolatilized in nitrogen and combusted in air at 1300 °C, using a laboratory-scale drop tube furnace, to prepare chars and ashes. The mineral properties of the coals as well as their derived chars and ashes were analyzed using a computer-controlled scanning electron microscopy (CCSEM). The results demonstrate that, during coal devolatilization, whereas quartz and kaolinite are generally stable for all the three coals, included and excluded Fe-rich minerals (i.e., pyrite and siderite) as well as excluded Ca-rich minerals (i.e., calcite and ankerite) are decomposed and some of the intermediate products are incorporated with aluminosilicates. During char combustion, quartz participates in combustion reactions and forms aluminosilicates. Whereas the mullite-like phase in the YQ and DT chars changes little, that in the CF char absorbs Fe/Ca-rich fine particles and is incorporated into Fe–Ca-aluminosilicate. Most of the Ca/Fe-rich intermediate products react with aluminosilicates to form Fe-, Ca-, and Fe–Ca-aluminosilicates. The interactions between Fe/Ca-rich minerals and aluminosilicates are also observed. Calcium in Ca-rich minerals and iron in Fe-rich minerals of the YQ anthracite and the CF lignite interact with aluminosilicates during both coal devolatilization and char combustion processes. However, for the DT bituminous coal, such interactions between Ca-rich minerals and aluminosilicates only take place during devolatilization. The interactions between excluded Fe/Ca-rich minerals and included aluminosilicates during coal devolatilization are also observed.