The Temperature Compensation Research Of Methane Gas Detection System Based On TDLAS

As the main component of natural gas, methane caused a great threat to industrial and life because of its flammable and explosive characteristics. The in-situ measurement of methane gas with high accuracy are of great significance to industrial, life safety and environmental protection. At present. TDLAS has became one of the most important technologies of methane gas in-situ measurement, however, the influences of detection caused by gas temperature changes has became one of the primary reasons that are restraining its growth. Therefore, temperature compensation algorithm with high accuracy and stability became the key problem. The paper offered a quadratic harmonic temperature compensation algorithm that without measuring gas temperature.The paper discussed the basic theory of TDLAS, confirmed the central wavelength of methane gas detection is1.65um, improved the detection accuracy by combine wavelength modulation with harmonic detection technology, and proved the feasibility of TDLAS. The paper discussed the influences of TDLAS caused by gas temperature, built model with temperature influence factors, analyze the main waveform changes of harmonic and deviation of detection result caused by temperature change, and also analyze the main parameters of TDLAS system, determined the temperature compensation method which is using the zero point as feature point to achieve temperature compensation, reduced the dependence of system to gas temperature, improved the detection accuracy.The paper established the theory model of temperature compensation, and theoretically, achieved a results that harmonic central peak variation reach a grade of10-3within a temperature range of-10-60℃, and the dependency of quadratic harmonic center peak to temperature reduced by17.5times. The test based on test sample proved that the model has a effect on temperature compensation, and the algorithm is simple and stable.