The Study Of Technique For Natural Gas Leak Detection Based On TDLAS

environment and security. Traditional detection methods can't achieve continuous in-sit monitoring. In addition, slow rapidity of response and low-precision are the shortcomings of traditional methods. Thus, this thesis applied Tunable Diode Laser Absorption Spectroscopy (TDLAS) to natural gas leak detection. TDLAS is a new method with the characteristics of high resolution, high sensitivity and rapidity of response. The TDLAS system was combined with Wavelength Modulation Spectroscopy (WMS), weak signal detecting and processing technologies, open long absorption path technique to meet the need of high sensitivity and continuous in-sit monitoring of natural gas leak. The system is used to monitory the concentration of CH4 and H2S in gas station, gas pipeline and tunnel.In this thesis, Micro Controller Unit technology, PLL and DDS technology are applied into the design of Signal Generator, to achieve a sine, sawtooth signal generating, and filtering and frequency multiplication, to meet the needs of WMS in TDLAS system. After the research of DFB laser technology, adjust the laser output wavelength, to meet the need of CH4 and H2S absorption lines. And, the noise which influenced the sensitivity of TDLAS was analyzed, and then the linear least-squares fitting will be introduced and applied to Data Processing.Finally, the system's performance was tested and proved to meet the requirements of environmental monitoring by measuring standard gases with different concentration of methane and carbon dioxide; and it's long-term reliability was tested by continue monitoring in Shengli-Oilfield, a good correlation was obtained and provided a good method of monitoring of natural gas leak in the process of develop High-sulfur gas field. The method has good prospects for the popularization and application in the development of sour gas. It has better economic, social and environmental benefits.