Study on spontaneous combustion thermal characteristic and change of active functional group of secondary oxidized coal
Taking Hls long-flame coal as the research object,TG and FTIR were used to test the change of thermal characteristic parameters during the secondary oxidation of coal.Characteristic temperature points T0-T5 were used to describe the spontaneous combustion process of the secondary oxidation coal samples.The heat release and comprehensive combustion coefficient S of the coal were calculated,and the changes of surface active functional groups of the pre-oxidized coal under different temperature conditions were analyzed.The research showed that with the increase of pre-oxidation temperature,T1of the coal sample showed a decreasing trend,T2 showed an increasing trend,and T3 showed a decreasing trend,while T4 and T5 showed no obvious change trend.The temperature range of the pre-oxidized coal was reduced in the stage of dehydration and adsorption,but the ability of oxygen absorption and weight gain was improved,and the combustion temperature was reached first.With the increase of pre-oxidation temperature,the heat release and the S of coal showed the trend of slow increase before decrease.The pre-oxidized coal had a positive effect on hydrogen bond content,aromatic CH and aliphatic CH content,and a large amount of active-OH,methyl and methylene were produced on the coal surface.The content of oxygen-containing functional groups increased first,then decreased and increased again with the increase of pre-oxidation temperature.
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