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针对多组分痕量气体检测中精确度差、灵敏度低等问题,设计了基于光源波长扫描技术的光声光谱式多组分痕量气体检测系统。系统采用单一超窄线宽半导体激光器作光源,设计了一阶纵向共振式多光程吸收光声池,通过正弦信号对光源波长进行调制,并结合二次谐波信号检测技术和超窄线宽激光特性,有效地消除了吸收池内的背景噪声和光源抖动的影响,实现了C2H2、CO和CO2多组分低浓度气体同时检测。实验结果表明,C2H2、CO和CO2多组分气体浓度测量线性相关度为0.99,最大相对误差小于2%,极限检测灵敏度分别为5×10-6、12×10-6和15×10-6;长时间稳定性实验,多组分气体浓度最大相对波动小于1.5%。系统精确度好、灵敏度高并具有较好的稳定性,可用于电力变压器故障气体实时在线监测。
Aiming at the problems of poor accuracy and low sensitivity in the detection of multi-component trace gas, a photoacoustic multi-component trace gas detection system based on wavelength scanning of light source was designed. The system uses a single ultra-narrow linewidth semiconductor laser as the light source, a first-order longitudinal resonant multi-path absorption photoacoustic cell is designed, the wavelength of the light source is modulated by the sinusoidal signal, combined with the second harmonic signal detection technology and ultra-narrow linewidth The laser characteristics can effectively eliminate the influence of background noise and light source jitter in the absorption cell and achieve the simultaneous detection of C2H2, CO and CO2 multi-component low-concentration gases. The experimental results show that the linear correlation of the concentration of C2H2, CO and CO2 gas is 0.99, the maximum relative error is less than 2% and the limit detection sensitivity is 5 × 10-6, 12 × 10-6 and 15 × 10-6 respectively For long term stability experiments, the maximum relative volatility of multi-component gas is less than 1.5%. System accuracy, high sensitivity and has good stability, can be used for real-time on-line gas fault monitoring of power transformers.