基于量子级联激光的大区域SF6泄露实时检测

Real-time Detection of SF6 Leakage in Large Area Based on Quantum Cascade Laser

采用量子级联激光器的可调谐半导体激光吸收光谱技术及可移动开放式光路系统在线检测泄露区域的SF6气体.光路系统位于高压组合电器间隔周围,与传感系统通过非接触组合.中红外激光器的工作温度在10℃且注入电流为680 mA时发射频率范围可覆盖SF6气体的选择波长.通过对大区域实验舱的内环境进行多次抽取分离,得到二次谐波吸收的精确背景吸收,利用10.55μm的可调谐激光传感系统对泄露扩散平衡后的SF6气体进行测量,扣减背景吸收后得到泄露SF6气体的二次谐波吸收光谱.研究结果表明:14.3m的开放式光路下,气相色谱-热导率检测器溯源校准数据与可调谐半导体激光吸收光谱技术检测一致性良好,最大偏差为2.26%,二次谐波最大信号幅值与测量浓度具有较高拟合度,拟合系数为0.998,SF6体积浓度的检测下限为1.8×10^-6.该研究可为SF6气体泄露提供一种全新的检测方法,从而实现高压组合电器大区域环境下SF6气体实时在线监测.

A tunable diode laser absorption spectroscopy technique using quantum cascade lasers and a movable open optical path system are proposed to realize on-line detection of SF6 gas in the leakage region.The optical path system is located around the interval of high-voltage combined appliances,and through the non-contact combination with the sensing system.The emission frequency range of the mid-infrared laser with injection current of 680 mA can cover the selected wavelength of SF6 gas at work temperature of 10℃.The precise background absorption of the second harmonic absorption is obtained by extracting and separating the internal environment of the large area laboratory module for several times.The leaked SF6 gas after diffusion equilibrium is measured by using the tunable laser sensor system with 10.55μm.After subtracting the background absorption,the second harmonic absorption spectrum of the leaked SF6 gas was obtained.Research results show that under the open light path of 14.3 m,gas chromatography-thermal conductivity detector traceability of calibration data with tunable diode laser absorption spectroscopy technology testing consistency is well,the maximum deviation is 2.26%.The second harmonic signal amplitude and largest measuring concentration have a high fitting degree with fitting coefficient of 0.998,and SF 6 volume concentration of the detection limit is 1.8×10^-6.The study can provide a new detection method for SF6 gas leakage,so as to realize real-time online monitoring of SF6 gas under large area environment of high voltage combined appliances.