Research on high performance combustible gas concentration detector based on pyramidal spectroscopy

WANG Boqiang; ZHANG Yiyong; ZHAO Xuezeng; WANG Zhuogang; QI Yue; JIANG Jian

doi:10.13225/j.cnki.jccs.2022.1552

Abstract：Non-dispersive infrared(NDIR)combustible gas concentration detectors can effectively detect gas leaks in mines to prevent gas leakage during the mining process and ensure the safe production of coal mines.In order to im-prove the detection accuracy,sensitivity,and robustness of the NDIR type combustible gas concentration detector,based on the pyramid beam splitter matrix,the internal optical structure of the sensitive element is newly designed.The multi-frequency signal superposition technology is used to modulate the infrared light source.The 4-channel com-bustible gas concentration redundancy algorithm based on the linear frequency modulation Z-transform(CZT)is de-signed.Also,the spectral refinement analysis is contacted through the characteristic frequency band of the signal to give the combustible gas concentration detection results and the confidence level of the detection results.The experiments show that the effective detection concentration of the detector is 10%-90%of the lower explosive concen-tration limit(5%of the lower explosive concentration limit of methane),and the confidence level of the detection re-sults is 0.014×10-6.The limit measurement concentration of the detector for combustible gases can reach 0.5×10-6,and the confidence level of the detection results is 0.01×10-6.Under the unfavorable condition that the detector opti-cal window is blocked by 2/3,the detector can still detect normally,and the confidence level of the detection re-sults can still reach 0.01×10-6.Under the extreme environment of 85%humidity and 100 mg/m3 dust concentration,the detector can still detect effectively and the confidence level of the detection result can still be at 0.01×10-6 level.The developed combustible gas concentration detector increases the detection sensitivity to the 0.01×10-6 level and can give the confidence level of the detection results.The designed optical circuit structure enables the detector to achieve a high-precision detection of combustible gases even in extreme environments with high humidity and dust.It effectively improves the detection accuracy,sensitivity,and robustness of the detector,making it adaptable to the harsh environment of coal mines.It can achieve very early detection of coal mine gas leaks,and can also reduce its maintenance cost.