Method and device for remotely measuring methane concentration by methane gas mass interface recognition and laser with adjustable measuring range

Abstract

The invention provides a method and a device for remotely measuring methane concentration by methane gas mass interface recognition and laser with an adjustable measuring range and relates to the field of gas detection and analysis. The device is composed of an STM32 controller, a laser device driving circuit, a laser device temperature control circuit, a photoelectric detection circuit, a lock phase demodulating circuit, a three-dimensional space laser measuring tracking device and an internally-arranged air velocity transducer, wherein the STM32 controller is in circuit connection with the laser device driving circuit, the laser device temperature control circuit, the lock phase demodulating circuit and the three-dimensional space laser measuring tracking device respectively; and the photoelectric detection circuit is connected with the lock phase demodulating circuit. The method is high in measurement speed which reaches ms-grade responding time, and has high measurement sensitivity which reaches ppm magnitude order; the maximum detection distance is 100 meters and the detection can be finished in one step in a range of 30 meters long, so that the detection efficiency is improved; the requirements on the environment are not high and influences on a measurement result are not caused in a detected gas atmosphere containing high dust and having strong corrosiveness; and by adopting a remote detection function, the detection of places which cannot be reached or are difficult to reach can be realized.

Description

technical field [0001] The invention relates to the field of gas detection and analysis, in particular to a method and device for methane air mass interface identification and adjustable range laser remote measurement of methane concentration. Background technique [0002] According to the principle of gas detection, methane gas detection methods can be divided into the following categories: gas-sensing detection method, gas chromatography detection method, optical interference detection method, differential detection method, tunable semiconductor laser absorption spectroscopy detection method, etc. Explanation: the problem of gas sensing detection method is that the detection performance is closely related to the production and process of sensitive components, and the detection results are also affected by environmental factors such as the temperature of the detection site. The detection response speed is slow, the components are easy to be poisoned and the service life is ...

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Problems solved by technology

[0002] According to the principle of gas detection, methane gas detection methods can be divided into the following categories: gas-sensing detection method, gas chromatography detection method, optical interference detection method, differential detection method, tunable semiconductor laser absorption spectroscopy detection method, etc. Explanation: the problem of gas sensing detection method is that the detection performance is closely related to the production and process of sensitive components, and the detection results are also affected by environmental factors such as the temperature of the detection site

The detection response speed is slow, the components are easy to be poisoned and the service life is short; the gas chromatography requires the qualitative data of the pure chromatogram of the analyte, and it is difficult to make a qualitative analysis of the mixture with unknown components. Additional reactions may occur during the adoption process, and the response time Long, unable to perform real-time measurement, complex measurement system, unable to achieve online measurement, only single-point monitoring, unable to reflect the overall situation of the measured environment; optical interferometry is difficult to achieve remote measurement, narrow linear range, poor long-term stability, and requires post-processing Processing; the tunable diode laser gas spectrum absorption detection method puts forward high requirements on the laser, which requires a wide tunable range of the light source, high frequency stability, high precision in temperature tuning and current tuning control, and a complex light source drive circuit. At the same time, lasers are more expensive

[0003] Most of the gas detectors used for methane produced by Hans in the United States and the 32A methane gas detector produced by Tokyo Gas Company in Japan now have large errors in the measurement of column density and concentration values ​​by users, and the false alarm rate At the same time, the handheld device is connected to the chassis through a rigid connection tube, which is easy to break during use; the latter has a relatively short measurement distance, and the working environment temperature must be above zero degrees Celsius to work normally, which limits its use. Dynamic response Slow, battery life can not exceed 1 hour

[0004] The most important thing is that domestic and foreign methane gas laser detection instruments and equipment mostly use the methane air mass column density value measured by TDLAS technology, and its unit is ppm.m. This result cannot display the current concentration of methane air mass in real time, and there is a big Bias, which is a major flaw in current measuring instruments

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