添加秸秆类生物质对长平煤灰熔融特性的影响

Influence of agro-biomass addition on Changping coal ash melting characteristics

借助高温热台显微镜、扫描电子显微镜-能谱仪、灰熔点仪和X射线衍射仪考察了添加稻草和棉秆两种秸秆对长平煤灰熔融特性的影响。研究结果表明添加两种秸秆都能有效地降低长平煤灰的熔融温度。在高温弱还原性气氛下,长平煤灰主要矿物组成为耐熔性石英和莫来石,而添加秸秆后产生了白榴石、尖晶橄榄石、钙长石等低温共熔化合物,使长平煤灰熔点降低。不同灰的高温熔融图像表明,煤灰在熔融过程中由于受热而使固相持续软化,形成了不利于难熔物分解的高黏度熔体。而煤和稻草的混合灰在熔融时形成了易发生流动的低黏度熔体,能够促进矿物质发生反应而更易熔融。

The effects of rice straw （DC） and cotton stalk （MG） addition on Changping （CP） coal ash melting characteristics were studied with high-temperature optical microscopy, scanning electron microscopy coupled with energy dispersive spectrometer （SEM-EDS）, standard ash fusion temperature （AFT） tests and X-ray diffraction （XRD） analyses. The AFT of CP coal could be reduced effectively by adding both agricultural residues. In weak reducing atmosphere at high temperature, refractory mullite and quartz were main minerals of CP coal ash. The presence of agricultural residues could form low melting eutectic minerals, such as leucite, ringwoodite and anorthite, decreasing the AFT of CP coal. High temperature images of ash particles showed that CP coal ash fusion behavior was prolonged softening and subsequent melting of solid phases that resulted in sluggish flow and depressed dissolution of the refractory constituents. However, during the melting process of DC blended CP coal ash, active melts with low viscosity that could promote the reaction between the minerals and quickly dissolve the residual refractory were formed.