基于TDLAS的火力发电厂锅炉燃烧CO浓度检测系统设计与应用

Design and application of CO concentration detection system for boiler combustion in thermal power plant based on TDLAS

为提升火力发电厂锅炉燃烧效率,基于可调谐半导体激光吸收光谱技术和长调制光谱检测技术,设计锅炉炉膛燃烧CO在线检测系统,同时对系统误差进行了计算分析。结果表明:通过锁相放大器对探测到的激光信号进行调解,可以减小噪声对检测精度的影响;造成检测系统误差的主要因素包括初始激光强度、吸收光程、温度、二次谐波峰值、压强和调制电流幅度等6项,且误差分配结果依次为0.1 mW、4 mm、1 K、2 mV、0.05 atm和0.02 mA;通过蒙特卡洛方法对误差分配结果进行验证,结果显示系统极限误差仅为0.023%,满足检测精度要求;基于误差分析和分配结果,搭建实验平台,对10组浓度为2.5%的CO气体进行了检测,结果表明:CO浓度检测绝对误差为-0.01%~0.01%,均远小于0.025%的误差要求,表明本系统具备较高的检测精度。

In order to improve the combustion efficiency of boiler in thermal power plant, based on tunable semiconductor laser absorption spectrum technology and long modulation spectrum detection technology, an on-line detection system of boiler furnace combustion CO is designed, and the system error is calculated and analyzed. The results show that the influence of noise on the detection accuracy can be reduced by adjusting the detected laser signal through the phase-locked amplifier;The main factors causing the error of the detection system include initial laser intensity, absorption optical path, temperature, second harmonic peak value, pressure and modulation current amplitude, and the error distribution results are 0.1 MW, 4 mm, 1 K, 2 mV, 0.05 atm and 0.02 mA in turn;The error distribution results are verified by Monte Carlo method. The results show that the limit error of the system is only 0.023%, which meets the requirements of detection accuracy;Based on the error analysis and distribution results, an experimental platform was built to detect 10 groups of CO gas with concentration of 2.5%. The results show that the absolute error of CO concentration detection is-0.01% ~ 0.01%, which is far less than the error requirement of 0.025%, indicating that the system has high detection accuracy.