Instrument and method for real time monitoring optical fibre distributed multi-point mash gas

Abstract

The invention discloses an optical fiber distributed multi-point methane real-time monitor based on the light wave modulation spectrometry and the monitoring method, a semiconductor DFB laser, an optical fiber splitter, a gas calibration pond, a laser control circuit board, a signal generative circuit board, a lock-in amplified board, a data acquisition card, a control module, a multi-channel analog signal selection switch and a driving circuit are arranged in the main case of the monitor, the main case is connected with miniature optical sensors in various underground detection optical path through dingle mode fibers. The wavelength modulation of a gas laser absorption spectrum is realized by a low frequency scanning signal and a high frequency modulation signal generated by a signal generative circuit. The laser wavelength shift is carried out adaptive adjustment by the built-in gas calibration pond so as to realize the locking of a methane absorption line. The distributed multi-point methane concentration monitoring in the underground coal mine is realized by the switching of the multi-channel analog signal selection switch.

Description

technical field [0001] The invention belongs to a gas laser spectrum measuring instrument and method, in particular to an optical fiber distributed multi-point gas concentration monitor and a monitoring method based on laser wavelength modulation technology and near-infrared tunable semiconductor laser absorption spectrum technology. Background technique [0002] The coal industry is the industry with the most serious casualties in industrial production in my country. According to statistics, the total number of deaths in coal mine accidents nationwide in 2007 was 3,770, of which the number of coal mine gas accidents and the number of deaths decreased compared with the previous year. The death rate per million tons is 1.516, but it is still much higher than other major coal-producing countries in the world. From the perspective of accident types, the main causes of serious accidents are gas explosions and gas outbursts. Gas is a general term for harmful gases attached to coa...

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Problems solved by technology

[0003] At present, the conventional monitoring of gas at home and abroad mainly uses mine gas catalytic sensors, but the catalytic elements have the disadvantages of unstable operation, frequent adjustments and short service life, which seriously restrict the reliability of mine gas detection.

Some domestic mines have established gas concentration monitoring systems, which are basically branched tree network structures. The main station of the control center is set up on the well, and multiple measurement and control substations are set up underground. The information of each substation is transmitted by a dedicated cable, but there are sensors. Disadvantages such as inflexible access and inconvenient follow-up

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