氧弹燃烧过程煤中氟的释放和捕集影响因素

Factors affecting release and capture of fluorine in coal during oxygen bomb combustion

为探究煤中氟元素在氧弹燃烧过程中的释放和捕集规律,揭示造成高灰高氟样品测定结果偏低的关键因素,选取不同灰分和氟含量的煤样为研究对象,采用热力学状态函数法,考察了煤质特性对氧弹内最高火焰温度和该温度下汽/氟质量比的影响,研究了煤质变化对氟释放和捕集率的影响规律。结果表明:样品的热值直接影响最高火焰燃烧温度和燃烧环境的汽/氟质量比,氟分解过程获得的有效热量是影响氟释放和捕集的关键因素,采用掺配苯甲酸提高样品的热值和降低样品的氟含量手段,可提高高灰高氟样品氟的释放和捕集率,提高最高火焰温度至2 800 K可将高灰高氟样品氟的释放和捕集率由52%~70%提升至85%~100%,可实现氟的全部释放与捕集。为拓展氧弹燃烧法测定氟含量的适用范围提供依据,也可为高氟煤应用中的固氟技术开发提供依据。

In order to explore the release and capture laws of fluorine in coal during oxygen bomb combustion,the key factors that lead to the low determination results of high-ash and high-fluorine samples were revealed.Selecting coal samples with different ash and fluorine contents as the research object,the the influence of coal quality characteristics on the maximum flame temperature and the vapor/fluorine ratio at this temperature in the oxygen bomb was analyzed by using the thermodynamic state function method.The effect on the release and capture rate of fluorine was also analyzed.The results show that the maximum flame temperature and the vapor/fluorine ratio of the combustion environment is directly affected by the calorific value of the sample,and the effective heat obtained in the fluorine decomposition process is the key factor affecting the release and capture of fluorine.The release and capture rate of fluorine in high-ash and high-fluorine samples can be improved by adding benzoic acid to increase the calorific value and reduce the fluorine content of the sample.The fluorine release and capture rate of high-ash and high-fluorine samples can be increased from 52%-70% to 85%-100% by raising the theoretical maximum temperature to 2 800 K,achieving the full release and capture of fluorine.This study can provide a basis for expanding the scope of application of oxygen bomb combustion method to determine fluorine content,and also provide a basis for fluorine fixation in the application of high fluorine coal.