摘要：
The mineral inter-reaction of blending coals during O2/CO2combustion was studied.Two coals, Meng coal and Pingqi coal, were blended by certain ratios.The blending coals were burned in a tube furnace with O2/CO2or O2/N2.Ash fusion temperature test, XRD, TG/DSC and thermodynamic calculation were employed to examine the melting behavior and mineral reactions of blending coal ashes during O2/CO2and O2/N2combustion in detail.The results show that: there is no a pronounced difference in the blending coal ash fusion temperature between O2/CO2and O2/N2combustion.More CaCO3produced during O2/CO2combustion suggests that O2/CO2atmosphere significantly prevents the decomposition of CaCO3.The changing of atmosphere has an impact on the transformation of Ca-containing minerals, and the reaction between Ca and mullite occurs significantly, which is easier in O2/CO2combustion to produce more low-melting phase that will aggravate the boiler slagging.When the blending ratio of Meng coal in blends with Pingqi coal is 75% or more, less mullite is present in blending coals, and thus the impact of atmosphere on Ca-mullite reaction is weaker.However, the atmosphere has a more impact on Fe-containing minerals and more Fe-glass phase will be formed during O2/CO2combustion, which will aggravate the boiler slagging.%对蒙煤与平七煤两种单煤及其按照不同比例组成的混煤,分别在O2/CO2和O2/N2气氛下,采用管式炉燃烧制取灰样;对灰样进行灰熔点、XRD及同步热分析(TG/DSC)测试,并进行相关热力学计算,分析了O2/CO2燃烧方式对混煤灰中矿物质间反应的影响.结果表明,常规灰熔点测试方法测得的两种气氛下的混煤灰熔点没有明显差别.O2/CO2气氛促进了煤灰/混煤灰中钙的碳酸化,且明显抑制了高温下CaCO3的分解.气氛的改变影响了含钙矿物的转化,进而影响了混煤中钙与莫来石反应生成低温共熔物;O2/CO2气氛下钙更易于与莫来石发生反应生成低温共熔物,从而会增加结渣倾向.当混煤中蒙煤比例达到或大于75%时,随着蒙煤比例的逐渐增加,莫来石含量减少,O2/CO2气氛对钙与莫来石之间的反应影响减弱,但对含铁矿物的影响更加明显,使其更易于生成含铁玻璃体,从而也会增加结渣倾向.
