耐熔剂对小龙潭褐煤灰熔融特性的影响

摘要

为探索提高小龙潭褐煤灰熔聚流化床气化过程中操作温度的途径,研究了氧化铝、二氧化硅、高岭土3种耐熔剂对小龙潭褐煤灰熔融特性的影响,在添加耐熔剂前后在氢气和二氧化碳的混合气氛下对小龙潭煤灰进行不同温度的热处理,对矿物组成进行了X-射线衍射(XRD)分析,从矿物质演变的角度分析了灰熔点变化的原因.结果表明:氧化铝、二氧化硅和高岭土3种耐熔剂均可使小龙潭煤的灰熔融温度明显上升.当氧化铝或二氧化硅的添加量(质量分数)为2.2％,或高岭土的添加量为3.0％时,均可使小龙潭煤的灰软化温度上升到1250℃以上.导致小龙潭煤的灰熔融温度高的主要原因是由于在高温下低熔点的钙长石和钙黄长石的生成.添加不同耐熔剂后灰熔点变化程度的差异由于生成的高熔点的莫来石含量的不同引起的.%In order to explore the method of improving the operating temperature of Xiaolongtan lignite ( XLT) during ash agglomerate fluidized-bed gasification, the effects of three kinds of refractory ( alumina, silicon dioxide and kaolinite) on the XLT ash fusion characteristics were investigated. The change of compositions of mineral under various temperatures with the atmosphere of CO2 and H2 mixture before and after adding refractory to XLT was analyzed by X-ray diffraction (XRD) ,and the reason that caused the increase of ash fusion temperature (AFT) was explained from the aspect of mineral transformation. The results show that three kinds of refractory can make AFTs of XLT rise apparently. When the adding mass fraction of alumina or silicon dioxide is 2. 2% ,or the adding mass fraction of kaolinite is 3. 0% , the soften temperature (ST) of XLT can be increased to above 1 250 ℃. The formations of low-melting of gehlenite and anorthite are the major reasons which lead to low AFT of XLT. The different rising degree of AFT of XLT by adding different refractory are mostly caused by the mullite content formed during ash heated.