Hydrogen Sulfide Gas Sensor And Signal Processing Technology

In recent years, H2S gas leak frequently in the production and living security issues lelated to H2S gas gradually become the focus of attention. Developing online real-time, efficient, rapid H2S gas detection system become urgent demands. Compared with the conventional sensors, optical fiber gas sensor have advantages that include the immunity to electromagnetic interference, suitable for long-distance online testing, and sensing probe could be placed in harsh environment. The absorption type optical fiber gas sensor is close to the practical and the most promising gas sensors. In this paper, the H2S gas sensor based on near-infrared spectroscopy absorption principle is studied, and the TMS320F2812based on DSP chip an embedded optical fiber gas sensor signal processing system is designed, the hardware circuit and software development processes are detailed.Based on the gas near infrared selective absorption theory and Lambert-Beer law, the broadband light source for detection of H2S gas is proposed. H2S gas center in selected absorption lines is the1578nm, it is the absorption strength spectral line approximately1.3×10-22cm-1(molecule· cm-2)-1;Using GRIN lens as collimating and focusing lens for transmission gas cell, and a method that using cascaded GRIN Lens to increase the optical path length is presented. Which the300mm gas absorption cell consists of3serial100mm short absorption cells and each short absorption cell is formed by two micro-GRIN lens. The influence of the high source intensity fluctuations can be eliminated by using the difference systems of the signal light path and the reference optical path.Weak signal processing is an important part of optical fiber sensor system. Theories about correlation detection and lock-in amplifier are studied. The TMS320F2812chip and CCS which is the development tool of the TMS320F2812are introduced. An analog signal detection system and a digital signal processing system based on DSP for optical fiber hydrogen sensors are designed. Some techniques involved in development process are discussed...