不同变质程度煤导热系数试验分析

Experimental analysis of thermal conductivity of different ranks of coal

煤自燃不仅严重威胁着矿井的安全生产,甚至会引发火灾事故造成资源浪费和人员伤亡。煤岩体之间的热传导是引起煤自燃的关键因素之一,因此对煤岩体的传热能力开展研究是很有必要的。煤的导热系数是判定煤岩热传导能力的重要参数。在本研究中,为了分析不同变质程度煤的导热系数,探究温度和含水量对煤样导热系数的影响,在不同环境温度和含水量情况下分别测试了焦煤、长焰煤、褐煤、无烟煤和不黏煤这5种不同变质程度的煤样。采用LFA457型激光导热仪对这几种不同变质程度煤样的导热系数进行了测定。此外,应用Pearson相关系数法分析了不同煤质指标对煤样导热系数的影响规律。试验结果表明:煤样的导热系数与其变质程度呈负相关,即随变质程度的增加而逐渐减小;当温度为-50~10℃时,煤样的导热系数随着温度升高而显著升高;在10~50℃时,煤样的导热系数呈现出先缓慢增大最后趋于平稳的趋势;煤样的变质程度越低,其含水量对导热系数的影响越大;Pearson相关系数法的分析结果表明煤质指标对煤样导热系数影响的重要程度依次为灰分、固定碳、挥发分和水分。该试验研究有助于了解不同变质程度煤导热系数的影响因素及变化规律,并可进一步为煤火灾害的防治工作提供一定的理论基础。

Coal spontaneous combustion is a serious threat in safe production of coal,which could result in a coal fire,causing waste of resources and serious injuries and fatalities.Heat transfer between coal and rock is one of the key factors causing coal spontaneous combustion.Thus,research on heat transfer between coal and rock is essential to reduce coal spontaneous combustion.The thermal conductivity of coal is a major parameter for determining the thermal ability of coal.In this study,we analyze the thermal conductivity of different ranks of coal and investigate the effect of temperature and moisture content on thermal conductivity.Five coal samples of different ranks,namely coking coal,long flame coal,lignite,anthracite,and non-stick coal,were tested respectively under different ambient temperatures and moisture contents.Meanwhile,the thermal conductivity of these five coal samples was measured by the LFA457 laser thermal conductivity meter.In addition,the Pearson correlation coefficient methodwas applied to explore the effect of different coal compositions on thermal conductivity.The results indicate that the thermal conductivity of coal samples is negatively correlated with thecoal rank.In another word,lower thermal conductivity is associated with higher coal rank.When temperature is -50~10 ℃,the thermal conductivity of coal increases swiftly with the increase of temperature.When temperature is 10~50 ℃,the thermal conductivity of coal increases slowly and then tends to be stable.A lower degree of coal maturity indicates a greater effect of moisture content on thermal conductivity.It is also found that ash has the most significant influence on thermal conductivity of coal,then followed by fixed carbon,volatile matter,and moisture.This experimental study provides an understanding of influence factors and variation laws of thermal conductivity of different ranks of coal,and further provides a theoretical basis for the prevention and control of coal fire disasters.