鉴于常规的标识性气体监测方法在响应速度、测量精度、使用寿命、实时性、监测目标种类、测量范围和应用场合等方面相比激光吸收光谱技术存在不足, 本文以可调谐半导体激光吸收光谱技术为依托, 选取合适的无干扰激光吸收谱线, 阐述了工业管道抽取式、管道原位在线对射式、扩散探头式(全量程激光监测一体机形式与多点无源传感器探头形式)、无组织排放开放光路式等多种形式的监测方法。上述系统的测量结果显示: 抽取式可实现CO、CO2、O2等不同多组分气体的同时测量; 管道对射式实现了O2及10 μL/L以下CO的高精度在线测量; 探头式则以CH4测量为例实现了响应时间T90=15 s, 监测极限小于150 μL/L, 泄漏报警准确率达100%; 开放光路形式以天然气集气站场测量CH4、C2H2、C2H4三种气体为例实现了0误报的监测能力。上述分析结果表明, TDLAS技术应用于工矿安全生产及安全预警方面的标识性气体监测是完全实用、有效、准确、可靠的。

On-line monitoring for identification gases is one of the most important goals in industrial production processes and safety warning areas. Compared with laser absorption spectroscopy, conventional monitoring methods are insufficient in terms of response speed, measurement accuracy, service life, real-time monitoring of a variety of monitoring targets, measuring range, and application scope. In this study, Tunable Diode Laser Absorption Spectroscopy (TDLAS) with an appropriate absorption wavelength was introduced and used for different applications: extraction method of industrial pipeline gases, in situ on-line opposite-type installation, diffusion probe method (integrated machine, multi-point passive transducer), and unstructured open-path monitoring. The detailed measurement results are as follows: The extraction system can be used to measure the concentrations of various gases, such as CO, CO2, and O2; Conventional O2 concentration and CO with a concentration less than 10 μL/L are measured based on the opposite-type system; The integrated machine and multi-point system uses CH4 measurement as an example to realize a response time T90=15 s, a monitoring limit less than 150 μL/L and a leakage alarm accuracy rate approaching 100%. Lastly, CH4/C2H2/C2H4 was selected to test the ability of the open-path system, which realizes an early warning ability of zero misstatements. According to long-time operation results, it is apparent that the TDLAS instrument is reliable, practical, and effective when applied to monitoring marking gases of industrial and mining safety production, and early safety warning.