基于标定直接吸收光谱方法的近红外乙烯检测  

Near-infrared C_(2)H_(4) Detection Based on Calibrated Direct Absorption Spectroscopy

作　　者：王前进 孙鹏帅 张志荣 蔡永军 黄文彪 庞涛 夏滑 吴边[2] Wang Qianjin;Sun Pengshuai;Zhang Zhirong;Cai Yongjun;Huang Wenbiao;Pang Tao;Xia Hua;Wu Bian(School of Environment Science and Optoelectronic Technology,University of Science and Technology of China,Hefei 230026,Anhui,China;Anhui Provincial Key Laboratory of Photonic Devices and Materials,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,Anhui,China;Key Lab of Environmental Optics&Technology,Anhui Institute of Optics and Fine Mechanics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,Anhui,China;Advanced Laser Technology Laboratory of Anhui Province,National University of Defense Technology,Hefei 230037,Anhui,China;PipeChina General Academy of Science&Technology,Langfang 065000,Hebei,China)

机构地区：[1]中国科学技术大学环境科学与光电技术学院,安徽合肥230026 [2]中国科学院合肥物质科学研究院安徽光学精密机械研究所光子器件与材料安徽省重点实验室,安徽合肥230031 [3]中国科学院合肥物质科学研究院安徽光学精密机械研究所中国科学院环境光学与技术重点实验室,安徽合肥230031 [4]国防科技大学先进激光技术安徽省实验室,安徽合肥230037 [5]国家管网集团科学技术研究总院分公司,河北廊坊065000

出　　处：《中国激光》2024年第8期267-274,共8页Chinese Journal of Lasers

基　　金：国家重点研发计划(2022YFB3207601,2021YFB3201904);国家自然科学基金(42005107,11874364,41877311);中国科学院合肥研究院“火花”基金(YZJJ2022QN02)。

摘　　要：实现乙烯气体(C_(2)H_(4))实时在线精确检测对石油化工、煤矿等行业安全具有重要意义,但是C_(2)H_(4)在近红外波段的谱线强度信息不明确,具有谱带吸收特征,且与CH4有明显的混叠干扰,因此对其浓度进行精确检测是目前激光吸收光谱测量面临的共性技术难题。将波长调制光谱中的标定方法与直接吸收光谱相结合,提出了一种适用于C_(2)H_(4)气体检测的标定直接吸收光谱法(CDAS)。该方法不需要激光吸收光谱反演过程中的确切谱线强度信息,并克服了波长调制光谱在测量过程中出现的非线性效应。为了避免特定工况(如煤矿)中CH_(4)的干扰,实验装置采用了高精度压强控制系统,并且在100 mbar(1 bar=105 Pa)稳定压强下实现了CH_(4)和C_(2)H_(4)混叠光谱的分离。实验过程中对1626 nm附近的CH_(4)和C_(2)H_(4)仿真和实测吸收光谱进行了分析,确定了C2H4的标定光谱范围,进而验证了该方法在体积分数低于100×10^(-6)的范围内,对C2H4气体的检测误差不超过-1.47×10^(-6),并且测量体积分数与标准体积分数之间的线性拟合优度达到了0.999。对体积分数为10×10^(-6)的C2H4直接吸收光谱进行分析,以1倍信噪比对应的浓度作为检测下限进行等效计算,得到检测下限为1.38×10^(-6)。在Allan方差分析中,积分时间为77 s时检测精度达到了0.04×10^(-6)。以上实验结果充分说明了标定直接吸收光谱法能够在近红外波段实现C2H4的精确检测,并为此类气体的检测提供了一种新思路。Objective The real-time detection of ethylene(C2H4)is significant for the safety of coal mines,the petrochemical industry,and other industries.Currently,the mainstream methods for C_(2)H_(4) gas concentration detection include gas chromatography and electrochemical sensors.Gas chromatography can separate multicomponent gases and avoid mutual interference.However,this method requires long-term preheating and frequent calibration,making it difficult to complete real-time measurements in industrial scenarios.Although electrochemical sensors have the advantages of small size and low cost,their selectivity is poor,and it is difficult to avoid cross-interference.In contrast,tunable diode laser absorption spectroscopy(TDLAS)has the advantages of real-time measurements,high sensitivity,and strong selectivity.They are widely used in industrial gas detection and environmental monitoring.Unfortunately,there are still some difficulties in real-time high-precision detection of C_(2)H_(4).First,information regarding the absorption line of C_(2)H_(4) in the near-infrared band cannot be obtained.Second,the absorption spectrum of C2H4 is described as complex band absorption.Third,the absorption spectra of C_(2)H_(4) and CH_(4) in the near-infrared band interfere with each other.Therefore,realtime high-precision detection of C_(2)H_(4) is a common problem that urgently needs to be addressed.Methods First,the gas concentration can be calculated using traditional direct absorption spectroscopy if the accurate parameters of the absorption line are known.However,for C_(2)H_(4),it does not contain an absorption line intensity within the near-infrared band in the HITRAN database.This results in an inability to use a calibration-free method to directly calculate the C_(2)H_(4) concentration.Notably,the concentration calculation method in wavelength modulation spectroscopy does not require accurate spectral line intensity.Therefore,the calibration concept of wavelength modulation spectroscopy is applied to the direct absorption spectrosco

关 键 词：光谱学 乙烯气体(C_(2)H_(4)) 近红外光谱 谱带吸收 标定直接吸收光谱 高精度压强控制 

分 类 号：O433.4[机械工程—光学工程]