O2/CO2燃烧气氛对混煤灰中矿物质间反应影响研究

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。

Effect of O2/CO2 combustion atmosphere on the mineral inter-reaction of blended coal ashes

The mineral inter-reaction of blending coals during O₂/CO₂ combustion 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/CO₂ or 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/CO₂ and O₂/N₂ combustion in detail. The results show that:there is no a pronounced difference in the blending coal ash fusion temperature between O₂/CO₂ and O₂/N₂ combustion. More CaCO₃ produced during O₂/CO₂ combustion suggests that O₂/CO₂ atmosphere 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/CO₂ combustion 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/CO₂ combustion, which will aggravate the boiler slagging.