对烟道CO进行连续在线监测,是实现燃烧过程的控制和优化、减少污染气体排放的有效手段。可调谐半导体激光吸收光谱技术是一种具有高灵敏、高分辨、快速响应特点的气体检测技术。利用半导体激光器可调谐、窄线宽特性,通过检测气体的一条吸收线实现气体浓度的快速检测。实验研究了基于开放式近红外可调谐半导体激光光谱技术的烟道CO检测方法,采用光通信用分布反馈(DFB)半导体激光器作为光源,通过检测1.58 μm附近CO的一条振动转动吸收线实现对烟道气体中CO浓度的实时监测,光学系统采用开放式双光程设计,并通过背景信号拟合的方法消除烟道中消光系数变化对检测的影响。系统的检测限约为0.125 g/m2(光程积分浓度),具有实时在线连续检测的能力,能够满足工业环境下燃烧炉烟道CO连续监测的要求。

Continuous and in-situ monitoring of flue gas CO is an effective way to optimize combustion efficiency and reduce pollutant emission. Tunable diode laser absorption spectroscopy (TDLAS) a trace gas detection technique with a high sensitivity, high selectivity and fast time response, based on the tunability and narrow linewidth features of diode laser. It can implement fast gas concentration measurement through an single isolated absorption line. Flue gas CO detecting system based on open-path near infrared tunable diode laser spectroscopy has been experimentally studied. Using a telecom distributed-feedback (DFB) diode laser as optical source, a rotational-vibratinal line of CO near 1.58 μm has been used for real time CO concentration measurement. Open dual-path optical configuration has been adopted in this system. Influence of optical extinction coefficient fluctuation has been avoided by background fitting and subtracting. The system detection limit is about 0.125 g/m2 (path integrated concentration), and can meet the demands of in situ measurements of combustion flue gas CO in industrial environments.