弱黏煤氧化过程中的燃点及微观结构变化特征研究

Study on Change Characteristics of Ignition Point and Microstructure in Oxidation Process of Weakly Caking Coal

利用煤燃点测定仪、比表面积及孔径测试仪和红外光谱仪,研究弱黏煤在不同温度预氧化的煤样燃点、比表面积和官能团变化规律,以揭示弱黏煤在氧化过程中燃点、比表面积、孔径和官能团变化特性。研究结果表明:随着预氧化温度逐渐升高,燃点出现波动但整体呈降低趋势。初次氧化后,煤样的比表面积增大约4倍;二次氧化后,煤样的比表面积比新鲜煤样的比表面积增大约32倍。新鲜煤样以大孔为主,中孔和微孔所占比例很小;初次氧化后,大孔比例急剧下降,中孔比例急剧升高且占主导地位;二次氧化后,煤样空隙体积减小,其中中孔体积急剧减小,微孔体积的比例迅速升高且占主导地位。随着预氧化温度升高,含氧官能团数量增加,饱和烃官能团数量减小,芳香环官能团数量基本不变。

Using a coal flash point tester, specific surface area and aperture tester, and an infrared spectrometer, the changes in the ignition point, specific surface area, and functional groups of coal samples pre-oxidized at different temperature were studied to reveal the ignition point and specific surface area, pore size and functional group change characteristics of weakly caking coal during oxidation. The results of the study show that as the pre-oxidation temperature gradually increases, the ignition point fluctuates but overall it decreases. After the initial oxidation, the specific surface area of the coal sample increased approximately4 times. After the secondary oxidation, the specific surface area of the coal sample increased by approximately 32 times than that of the fresh coal sample. The large coal samples mainly consist of macropores, and the proportions of mesopores and micropores are very small. After the initial oxidation, the proportion of macropores decreases sharply, the proportion of mesopores sharply rises and dominates; after the secondary oxidation, the void volume of coal samples decreased, in which the volume of the mesopore sharply decreases, the proportion of the micropore volume increased rapidly and dominated. As the pre-oxidation temperature increases, the number of oxygen-containing functional groups increases, the number of saturated hydrocarbon functional groups decreases, and the number of aromatic ring functional groups does not change substantially.