Study On Mine Gas Concentration Monitoring System Based On TDLAS

Mine coal is important resource of our nationa l economy development, but recently gasaccidents have been the restrictive factor to our coal industria l safety production. So it is veryimportant to coal mine safety production and economic society construction while realizingconvenient, accurate and real-time monitoring to mine gas.Spectrum absorption sensing technology bases on the selective absorbability of gasmolecule, namely different gases have their own characteristic absorption peaks due to energydistribution in molecular structure, which decides the selectivity and identification ofspectrum absorption sensing technology. Comparing with widely adopted catalytic sensor andgas-sensitive detection, it has the better sensitivity, resolution and anti-interferenceperforma nce, and it also can realize real time monitoring. So it has become the developmenttrend of gas measure technology.While using the ma in component of mine gas methane as the target sample , this paperresearches and designs the gas concentration monitoring system based on TDLAS andharmonic detection. After analyzing the theory of near-infrared selective absorption of gas, itdescribes the academic base of the measurement of the gas by absorption theory and confirmsthe absorption spectra of methane. Different mathematica l models of gas concentrationharmonic measurement are built up. In the optica l part, according to detection requirements itselects the LD, LD drive and photodetector. In the signa l modulation part, the paper designsthe weak signa l measure circuits with the core of lock-in technology, and using the lightsource modulation harmonic modulation to realize the measure. In the data processing part, itdesigns the controlling and calculating module based on MSP430, as well as LCD displa ycircuit. In the data transmission part, it researches and confirms the wireless data transmissionstructure, and designs the wireless interface circuit by Bluetooth module ROC101007/1. The system is built up with the basic purpose of high performa nce and convenient operation, and itcan be integrated. After experimental demonstration in the same or similar conditions andtheoretica l calculation, the confirmed concentration mathematica l model is feasible, and bothsensitivity and resolution of system can meet the requirements of practica l monitoring in coalmine.