预氧化浸水煤体表面结构变化及复燃特性*

为研究预氧化长期浸水煤体孔隙结构变化及贫氧复燃特性，以长焰煤原煤（RC）、浸水煤(S200)、预氧化200浸水煤(O200I200)、预氧化300浸水(O300I200)煤为研究对象，采用N2吸附、电镜扫描、热重实验手段，在21%,15%,10%,5%氧浓度下进行实验分析。结果表明:浸水后煤样比表面积增大，低温氧化最大质量变化率（DTG）较高，促进低温氧化过程煤氧复合反应；预氧化浸水煤样平均孔径增加，初始放热温度较小，总放热量增加，其中O200I200煤样热参数相对较大。随氧浓度增加，各煤样着火点温度减小，活化能增加，O200I200煤样的这2个参数较小；随氧浓度降低，煤样初始放热温度增加，最大放热量与总放热量减小。O200I200煤体孔隙较发达，锁水能力较强，持续升温后氧化能力较强，更易复燃。

Surface structure changes and re-ignition characteristics of pre-oxidized and water-immersed coal

To study the change of pore structure of the pre-oxidized and long-term water-immersed coal and its oxygen-lean re-ignition characteristics,taking the raw long flame coal (RC),water-immersed coal (S200),pre-oxidized 200 and water-immersed coal (O200I200),pre-oxidized 300 and water-immersed coal (O300I200) as the research objects,the experimental analysis were conducted under the oxygen concentration of 21 %,15 %,10 % and 5 % respectively by means of the nitrogen adsorption,scanning electron microscopy and thermogravimetric experiments.The results showed that the specific surface area of coal samples increased after immersion in water,and the maximum mass change rate (DTG) of low-temperature oxidation was higher,which promoted the coal-oxygen composite reaction in the low-temperature oxidation process.The average pore diameter of pre-oxidized and water-immersed coal samples increased,the initial heat release temperature was smaller,and the total heat release increased.The thermal parameters of the O200I200 coal sample were larger than those of the other coal samples.As the oxygen concentration increased,the ignition temperature of each coal sample decreased,and the activation energy increased,while these two parameters of the O200I200 coal sample were smaller.With the decrease of oxygen concentration,the initial heat release temperature of coal samples increased,the maximum heat release and total heat release decreased.The O200I200 coal body had more developed pores,stronger water-locking ability,and stronger oxidation ability after the continuous heating,which was easier to occur the re-ignition.