Methane (CH4) plays a crucial role in various aspects of human life, particularly in industrial processes and environmental monitoring. This study presents a CH4 measurement system based on direct absorption spectroscopy (DAS) technology, utilizing diode lasers targeting absorption lines near 1653.7 nm. The system is designed to operate within a measurement range of 0-10% CH4 concentration. Laboratory evaluations demonstrate excellent linearity with the correlation coefficient of 0.99999 and the linear error of 0.20%FS. Long-term stability tests show a zero-point drift of 0.31%FS over 20 hours of continuous nitrogen (N2) input. Additionally, the system achieves a methane detection limit of 12.6 ppm with the integration time of 2 seconds. Field application tests confirm the system's reliability and suitability for high-precision CH4 detection in industries such as steel manufacturing, environmental protection, natural gas processing, and coal mining. The DAS-based system offers outstanding linearity, stability, and sensitivity, making it a valuable tool for methane detection across diverse industrial applications.
Liu et al. (Thu,) studied this question.