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采用可调谐激光吸收光谱(TDLAS)技术和光分路技术,实现了多通道光纤可燃气体监测系统的研制。系统中,监测仪部分采用分离式设计,无源传感探头和有源仪表之间通过光纤连接,含有浓度信息的光信号通过光纤传输到仪表进行处理。传感探头仅由气室和光纤组成,不带有任何电路,可以保证探头的本质安全性和抗电磁干扰能力。设计了乘法解调电路,以解决光纤传输产生的相位延时,而导致测量结果偏差的问题。测试结果表明,本文系统能够实现现场非电、远程、长期在线和分布式气体浓度监测预警预报,且检测结果不受光纤长度变化的影响,在工业标准的100最低爆炸极限(LEL)测量范围内能够正确检测CH4气体浓度值,检测灵敏度为0.1LEL。
Using tunable laser absorption spectroscopy (TDLAS) technology and optical branching technology, a multi-channel optical fiber combustible gas monitoring system was developed. In the system, the monitor part adopts the separated design, the passive sensing probe and the active instrument are connected through the optical fiber, and the optical signal containing the concentration information is transmitted to the meter through the optical fiber for processing. Sensing probe only consists of gas chamber and optical fiber, without any circuit, to ensure the intrinsic safety of the probe and anti-electromagnetic interference ability. The multiplication and demodulation circuit is designed to solve the problem of phase delay caused by optical fiber transmission and lead to the deviation of measurement results. The test results show that the system can realize on-site non-electrical, remote, long-term on-line and distributed gas concentration monitoring and forecasting, and the test results are not affected by the change of optical fiber length. Under the industry standard 100 minimum explosion limit (LEL) CH4 gas concentration can correctly detect the value of detection sensitivity of 0.1LEL.