Methane Monitoring System Based On TDLAS

With the continuous deterioration of the environment, humans havegradually realized the importance and necessity of protecting theenvironment. Although methane in the air is much lower than the amount ofCO2, it has a significant impact on global warming as well as CO2, the26%of greenhouse effect is caused due to methane, the same amount of methanecauses greenhouse22times that of CO2. Therefore, real-time onlinemeasurement of the methane gas concentration has important significancefor the protection of the environment.Tunable diode laser absorption spectroscopy (TDLAS) has highresolution, high sensitivity and good selectivity; It has been one of the mosteffective methods of trace gases online analysis, especially the wavelengthmodulation technique has been widely used in the field of chemical researchand gas pollution monitoring. The main contents of the paper are as follows:(1) Analyze the advantages of the TDLAS technology and its applicationin the methane gas monitoring system.(2) Discuss the basic principles of molecular absorption spectroscopy,wavelength modulation and second harmonic detection technology.(3) Describe the composition of the methane gas monitoring system,including device selection and circuit design, such as scanning circuit,modulation circuit, photoelectric detection circuit, the lock-in amplifiercircuit, signal acquisition circuit.(4) Describe the system’s overall software design, analyze the systemnoise sources and discuss the concentration inversion method and filteringalgorithm.