煤灰成分催化指数对焦炭反应性及反应后强度的影响

Effect of Catalytic Index of Coal Ash Composition on Coke Reactivity and Strength after Reaction

文章以神华烟煤为研究对象,采用热重分析仪、X射线荧光光谱仪、X射线衍射仪和激光粒度分布仪等分析手段考察了不同温度下CaO-MgO复合物对煤灰熔融特性以及煤灰中矿物质组成变化规律的影响。在此基础上,利用固定床反应器模拟气化炉内高温环境,通过改变煤灰中各组分含量来制备具有不同催化指数的煤灰样品,并将其与高钙灰混合制成半焦进行工业试验;同时结合扫描电子显微(SEM)、能谱(EDS)和压汞法分别从微观结构、化学元素组成和孔隙特征三个方面深入探讨了煤灰中各组分对焦炭反应性及反应后强度的作用机理。结果表明:随着CaO/Al_(2)O_(3)摩尔比由0增加到1.5时,煤灰中莫来石相逐渐减少,而石英相则相应增多;当CaO/Al_(2)O_(3)摩尔比继续升至2.0时,煤灰中出现大量方镁石晶体。这说明适量添加CaO可以促进煤灰中硅酸盐矿物向铝酸盐矿物转变,进而提高煤灰的反应活性。

Taking Shenhua bituminous coal as the research object,the influence of CaO-MgO composite on the melting characteristics of coal ash and the change of mineral composition in coal ash at different temperatures was investigated by means of thermogravimetric analysis,X-ray fluorescence spectrometer,X-ray diffraction and laser particle size distribution instrument.On this basis,the f ixed-bed reactor is used to simulate the high-temperature environment in the gasif ier,and the coal ash samples with different catalytic indexes are prepared by changing the content of each component in the coal ash,and the coal ash is mixed with high calcium ash to make semi-coke for industrial test.At the same time,combined with scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and mercury intrusion method,the effect mechanism of each component in coal ash on coke reactivity and strength after reaction was discussed in detail from three aspects of microstructure,chemical element composition and pore characteristics.The results show that when the molar ratio of CaO/Al_(2)O_(3) increases from 0 to 1.5,the mullite phase in coal ash decreases gradually,while the quartz phase increases correspondingly.When the molar ratio of CaO/Al_(2)O_(3) continues to rise to 2.0,a large number of periclase crystals appear in the coal ash.This shows that proper addition of CaO can promote the transformation of silicate minerals into aluminate minerals in coal ash,and thus improve the reactivity of coal ash.