褐煤热解与燃烧时矿物转化和细灰形成的CCSEM研究

在沉降炉中进行了一种典型中国褐煤的热解与燃烧实验,热解气氛为N2,燃烧气氛为O₂/N₂=21:79,采用CCSEM分析原煤、煤焦与煤灰。CCSEM分析结果表明,铁氧化物、石英、黄铁矿、伊利石和高岭土是煤中主要的矿物成分,同时也是主要的外在矿成分,褐煤中57.26%的矿物粒径小于10μm。在热解与燃烧过程中,煤中主要矿物发生了明显转化。富Si矿物和硅铝酸盐在热解和燃烧过程中可能发生了破碎;而富Fe矿物部分明显破碎生成细小矿物,部分外在矿直接转化,未发生明显破碎。细灰少量来自于细小富硅矿、石英和铁氧化物等矿物的直接转化,70%以上的细灰由Ca、Fe含量很高的混合硅铝酸盐组成。

CCSEM Investigation on the Mineral Transformation and Fine Ash Formation During Lignite Pyrolysis and Combustion

The pyrolysis and combustion of a Chinese lignite was conducted in a laboratory-scale drop tube furnace（DTF）.The coal char was prepared in N₂ and the combustion atmosphere of coal was O₂/N₂=21:79.Coal,char and ash were analyzed by CCSEM for studying the mineral transformation and fine ash formation during pyrolysis and combustion process.The CCSEM results indicate that:iron oxide,quartz,pyrite,illite and kaolinite form the bulk of the minerals as well as most excluded minerals,the fine minerals<10μm account for 57.26%.The minerals in coal undergo significant changes during pyrolysis and combustion.Aluminasilicates and the minerals rich in Si fragment possibly,meanwhile part of minerals rich in Fe fragment into fine ash and part of excluded minerals evolve directly into ash particles during pyrolysis and combustion.A small portion of the fine ash particles come from the direct transformation of fine Si-Rich,quartz and iron oxide,70%of that is composed of mixed aluminasilicates having high Ca and Fe content.