摘要
H2S,CH4多组分气体浓度测量技术的研究对石油石化行业的安全生产有重要意义.基于中红外TDLAS技术,选用中心波长为8.309 μm的量子级联激光器(Quantum Cascade Laser,QCL)为检测光源,搭建30 m长距离的遥测实验系统,使用WMS波长调制法对H2S,CH4气体的吸收谱线进行连续调谐与扫描,并对高频正弦载波进行了最优深化调制,实现了H2S,CH4多组分气体的同时测量.实验将H2S与5%体积分数的高浓度水汽进行混合测量,分析并验证了该波段的水汽吸收难以对测量造成交叉干扰的优良特性,并利用Savitzky-Golay平滑滤波器提高了检测信号的信噪比.通过遥测实验,分析了 15 m,30 m不同遥测距离对检测信号的影响,并利用增加积分时间与计算信噪比的方法,得到了128.75×10-9 m的遥测最低限.最后,Allan方差的计算结果表明,当积分时间为183 s,142 s时,系统对H2S,CH4气体的最低检测下限分别为0.593×10-9和1.160×10-9.本文的研究结果为中红外波段H2S,CH4多组分气体的高灵敏度、同时测量提供了一种有效途径,为多组分气体的遥测应用提供了参考.
Abstract
The research of hydrogen sulfide(H2S)and methane(CH4)concentration measurement tech-nology is of great significance to petroleum and petrochemical industry.In this paper,a Quantum Cascade Laser(QCL)with a center wavelength of 8.309 μm was selected as the detection light source based on Tunable Diode Laser Absorption Spectroscopy(TDLAS)technology.A 30 m long distance sensing sys-tem was established by using Wavelength Modulated Spectroscopy(WMS)technology to measure the mixture of H2S and CH4 gases.The experiment mixed H2S with 5%volume fraction of water vapor for measurement,and it showed excellent absorption characteristics in this band,with less cross-interference.Through sensing experiments,the impact of different sensing distances of 15 m and 30 m on the detection signal was analyzed.By increasing integration time and calculating the signal-to-noise ratio,a minimum sensing limit of 128.75×10-9 m was achieved.Finally,Allan variance calculations revealed that when in-tegration time was 183 s and 142 s,the lowest detection limits for H2S and CH4 were 0.593×10-9 and 1.160×10-9,respectively.The results provide an effective method for remote measurement of highly sen-sitive H2S and CH4 multi-component gases and ensure safe operation in a variety of industrial environ-ments.
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