The continuous monitoring of H<sub>2</sub>S gas concentration is a common problem in natural gas desulfurization process technology. Tunable diode laser absorption spectroscopy (TDLAS) is a preferred technology for continuous monitoring of gas in industrial sites, because of its high selectivity, high sensitivity, and fast response. We discuss the technical solutions of on-line monitoring of H<sub>2</sub>S in natural gas desulfurization process technology based on TDLAS, and study the security design of monitoring system in inflammable and explosive areas. We also design a weak photocurrent signal converting circuit and perform experiments on transmission characteristics of different distances. The signal-to-noise ratio (SNR) of laser absorption spectrum does not decrease after the 1 500-m transmission. The detection limit is 300 ppb. The system can be operated stably and reliably, and satisfies the need for continuous monitoring of the H<sub>2</sub>S in natural gas desulfurization process.
© 2012 Chinese Optics Letters
Remote Sensing and Sensors
Liming Wang, Yujun Zhang, Hongbin Li, Yi Zhou, Kun You, Ying He, and Wenqing Liu, "Study on long distance transmission technique of weak photocurrent signal in laser gas sensor," Chin. Opt. Lett. 10, 042802- (2012)