生物质与烟煤混合灰熔融特性影响因素的研究

为探究气氛、混合比及残炭含量对生物质与煤混合灰熔融特性的影响,将松木屑灰与乌海烟煤灰按不同质量比混合,采用智能灰熔点仪测定各混合灰样在不同气氛下的灰熔融温度,X射线衍射仪从矿物质演变角度分析混合灰熔融温度变化的原因。结果表明,由于铁尖晶石和铁橄榄石的生成,使混合灰的熔融温度在弱还原性气氛下比氧化性气氛下低,且差值的大小与混合灰中Fe含量有关;随松木屑灰含量的增加,钙铝黄长石、镁黄长石、白榴石等低温共熔物的生成量增加,使混合灰的熔融温度降低;此外,由于Fe-C共熔体(Fe_xC_y)的生成、灰锥局部还原性气氛及残炭的"骨架"作用,使混合灰的熔融温度随煤灰中残炭含量的增加呈现先升高后降低再升高的趋势。

Influence factors for fusion characteristics of mixed ash between biomass and bituminous coal

Effects of atmosphere, mixing ratio and residue carbon on ash fusion characteristics of biomass and bituminous coal were investigated. The pine sawdust ash was mixed with Wuhai bituminous coal ash at different mass ratios. The ash fusion temperatures (AFTS) of the mixed ash in different atmospheres were determined by ash-melting point measuring device. X-ray diffraction ray was used to investigate the reason for AFTs variation from the perspective of minerals evolution. The result shows that AFTs of mixed ash in weak reducing atmosphere is lower than that in oxidizing one due to formation of fayalite and hercynite. In addition, the difference in AFTs under reducing and oxidizing atmosphere is related to the content of Fe in the mixed ash. The increment of pine sawdust ash favors generation of gehlenite, akermanite and leucite ect., which can be classified as low temperature eutectics and help to reduce the AFTs of mixed ash. Moreover, the AFTs of the mixed ash increase initially and decrease afterwards and then increase again with the increment of residue carbon content in coal ash, due to formation of Fe-C eutectic (Fe_xC_y), local reducing atmosphere and skeleton action of residue carbon.