Application of a novel detection approach based on non-dispersive infrared theory to the in-situ analysis on indicator gases from underground coal fire

非分散红外光谱分析技术在煤矿火灾气体在线检测中的应用

Coal mine fires,which can cause heavy casualties,environmental damages and a waste of coal resources,have become a worldwide problem.Aiming at overcoming the drawbacks,such as a low analysis efficiency,poor stability and large monitoring error,of the existing underground coal fire monitoring technology,a novel monitoring system based on non-dispersive infrared(NDIR)spectroscopy is developed.In this study,first,the measurement principle of NDIR sensor,the gas concentration calculation and its temperature compensation algorithms were expounded.Next,taking CO and CH_(4) as examples,the liner correlation coefficients of absorbance and the temperature correction factors of the two indicator gases were calculated,and then the errors of concentration measurement for CO,CO_(2),CH_(4) and C_(2)H_(4) were further analyzed.The results disclose that the designed NDIR sensors can satisfy the requirements of industrial standards for monitoring the indicator gases for coal fire hazards.For the established NDIR-based monitoring system,the NDIRbased spectrum analyzer and its auxiliary equipment boast intrinsically safe and explosion-proof performances and can achieve real-time and in-situ detection of indicator gases when installed close to the coal fire risk area underground.Furthermore,a field application of the NDIR-based monitoring system in a coal mine shows that the NDIR-based spectrum analyzer has a permissible difference from the chromatography in measuring the concentrations of various indicator gases.Besides,the advantages of high accuracy,quick analysis and excellent security of the NDIR-based monitoring system have promoted its application in many coal mines.

煤矿井下火灾气体的实时监测对于实现采空区自燃危险性辨识,防范重特大热动力灾害发生,保障煤矿安全生产至关重要。为解决现有非防爆型异地检测技术气体分析速度慢、系统误差大、无法实现原位在线监测的缺陷,在此提出基于非分光红外光谱(NDIR)技术的气体传感器浓度计算方法,推导了温度补偿后的NDIR传感器气体浓度计算公式;随后,以CO和CH_(4)为例计算了吸光度线性系数和温度修正系数,并进一步对比测试了CO、CO_(2)、CH_(4)和C_(2)H_(4)的计算精度和稳定性,结果表明基本误差和定量重复性均优于煤炭行业标准要求。基于NDIR技术设计了具有本质安全和防爆性能的监测主机、配套子系统及软件平台,以实现煤矿井下气体的就地采集、有源预处理、原位在线分析。现场应用表明:大南湖一矿NDIR气体在线监测与地面色谱分析的4种气体浓度偏差均在标准允许范围内。基于NDIR的气体监测系统具有精度高、分析速度快、安全性好等优点,已经在全国40余对矿井推广应用,为评价煤矿井下热动力灾害的发生发展状态、提升防灾减灾救灾能力提供了科学依据。