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煤热解中痕量乙烯在线激光吸收光谱检测

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为了实现煤热解过程中痕量乙烯(C2H4)标识气体的在线识别与检测,结合波长调制与长光程技术,搭建了煤热解乙烯在线激光吸收光谱检测装置.采用中心波长为1 620 nm通信波段DFB激光器作为激光光源,有效光程为15 m的多光程吸收池为样品吸收池,利用SR830进行波长解调,通过二次谐波信号反演得到乙烯浓度.使用高精度流量控制器,利用高纯氮气稀释乙烯配比,制备得到10×10-6到90×10-6的标准乙烯样气,其线性拟合的相关系数R2为0.998 9;对浓度为20×10-6 的乙烯进行连续4 000 s的Allan方差分析,实验结果表明,检测极限为121×10-9.为了研究不同气体氛围下煤热解过程中乙烯浓度的演化规律,控制气体流速为150 mL/min,分别在氮气、空气以及合成空气中对乙烯标识气体的释放过程进行热重分析实验.研究发现,当温度小于500℃时,3种气体环境下乙烯释放量较少且基本一致,当温度在500～700℃时,氮气环境中乙烯释放量要远高于其他两种气体,但空气中乙烯释放的增速最快,最大释放量约为40×10-6,温度高于700℃时乙烯释放量均开始减少.这一结果为进一步探索煤热解中乙烯的生成机理提供了理论和实验基础.
Online laser absorption spectroscopy detection of trace ethylene in coal pyrolysis
To achieve the online identification and detection of trace ethylene gas during coal pyrolysis,we constructed a vinyl gas concentration detection system using tunable diode laser absorption spectroscopy(TDLAS).This system combines wavelength modulation with long optical path technology.We employed a distributed feedback(DFB)laser with a central wavelength of 1 620 nm,situated in the communication band,and a 15-meter long optical path cell for sample absorption.The SR830 was used for wavelength de-modulation,enabling us to determine ethylene concentrations through second harmonic signal inversion.We used high-precision flow controllers to dilute ethylene with high-purity nitrogen gas,creating standard ethylene gas samples with concentrations ranging from 10×10-6 to 90×10-6,achieving a linear fitting cor-relation coefficient R2 of 0.998 9.An Allan variance analysis experiment on a 20ppm ethylene sample over 4 000 s determined the minimum detection limit to be 121×10-9.To examine the evolution of ethylene concentration in various gas environments during coal pyrolysis,we maintained a gas flow rate at 150 mL/min.We analyzed the online release process of identified ethylene gas in nitrogen,air,and synthetic air(22%oxygen,78%nitrogen)environments.Our findings revealed that below 500℃,ethylene release in all three environments was low and consistent.Between 500 to 700℃,ethylene release in a nitrogen envi-ronment was notably higher than in the other two gases,with the release rate in air being the fastest,peak-ing at about 40ppm.Above 700℃,ethylene release in all environments began to decline.These results provide a critical scientific basis for further exploration into the mechanism of ethylene generation during coal pyrolysis,the refinement of coal pyrolysis techniques,the enhancement of coal utilization efficiency,and the advancement of environmental preservation.

tunable diode laser absorption spectroscopyethyleneallan variancewavelength modulation

段政、孟星星、李凯亮、孙小聪、田亚莉、宫廷、李传亮、邱选兵、蔡廷栋

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太原科技大学 应用科学学院,山西省精密测量与在线检测装备工程研究中心,山西省光场调控与融合应用技术创新中心,山西 太原 030024

江苏师范大学 物理与电子工程学院,江苏 徐州 221116

可调谐半导体激光吸收光谱技术 乙烯 Allan方差 波长调制 煤热解

国家自然科学基金国家自然科学基金国家自然科学基金山西省留学人员科技活动项目山西省省筹资金资助回国留学人员科研项目山西省基础研究计划太原科技大学科研启动资助基金太原科技大学科研启动资助基金

U18101295207614512304403202300312023-1512022030212222042022212420232035

2024

10.37188/OPE.20243205.0670

光学精密工程
中国科学院长春光学精密机械与物理研究所 中国仪器仪表学会

光学精密工程

CSTPCD北大核心
影响因子：2.059
ISSN：1004-924X
年,卷(期)：2024.32(5)
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