【摘要】 为了解低挥发分煤飞灰热处理时方石英的形成机理,使用X射线衍射(XRD)分析方法对一台燃烧低挥发分煤的W型火焰锅炉的现场煤粉、飞灰及飞灰热处理样品的物相组成进行了研究。锅炉空预器飞灰和炉膛飞灰均没有方石英存在,在飞灰950℃热处理时仍未有明显的方石英生成,经1050℃热处理飞灰中开始有方石英生成,并随加热时间的延长而增加。飞灰中可转化为方石英的非晶质SiO2是由煤中的高岭石等粘土矿物分解得到的,即煤中高岭石在煤粉锅炉内短暂加热的过程中只分解生成莫来石和非晶质SiO2,不生成方石英。更多还原

【Abstract】 The phase compositions of pulverized fuel and fly ash from a W-flame boiler that burns low volatile coals and the phase compositions of thermally treated fly ash samples were analyzed using X-ray diffraction to determine the cristobalite formation mechanism in the thermal treatment of low volatile coal fly ash.The results show that the fly ash collected in the air preheater and on the water-cooled walls does not contain cristobalite,with no cristobalite formed in the thermally treated fly ash at 950℃.Cristobalite appears at 1 050℃ with its content increasing with increasing heating time.The results also show that cristobalite is formed through the transformation of amorphous silica in the fly ash which originates from the decomposition of kaolinite and other clay minerals in low volatile coals during the very short heating process in the boiler furnace,with mullite being the other decomposition product.更多还原