Study Of Optical Fiber Sensor For SO₂ Concentration Based On LaBVIEW

Sulfur dioxide (SO₂) exhausted from electric power plants, boilers, industrial plants by the combustion of fossil fuel, are representative air pollutant gas species causing acid precipitants. Recently, the suppression of the SO₂ gas emission into the atmosphere is an urgent issue for the environmental conservation. In order to effectively reduce the SO₂ gas emission, it is essential to develop the SO₂ gas sensing tool which can detect SO₂ gas rapidly and exactly at every emitting site.This paper has analyzed many methods which are used in the detecting of sulfur dioxide concentration and analyzed the condition of sulfur dioxide concentration detector home and abroad, on the basis of studying and summarizing the latest achievements of gas detecting systematically and comprehensively, conclusion that using ultraviolet fluorescence method.Fluorescence concentration sensing mechanism has been studied, uv fluorescence gas concentration detecting method has been discussed, and mathematical model of relationship between fluorescence intensity and sulfur dioxide concentration has been established, thus, establishing a good basis for the reasonable design of system.The main design scheme of fluorescence fiber gas detecting system has been put forward, including lamp-house, optical filter, fluorescence fiber system, light detector and fluorescence signal detecting system, while the design principle and methods are described, and finished the design of every unit finally. Furthermore establishing theory basis for experimental study by analyzing the working principle of the whole system, characteristics of every component modules and selection basis. This paper proposed a new thought of double optical path fiber detecting system, which can detect the fluctuation of light source intensity and overcame the errors which existed in single optical path caused of the change of light source intensity at different time. In software part, a signal acquisition system based on virtual instrument is developed, by using LabVIEW, we can acquire the fluorescence signals which reflect the sulfur dioxide concentration, and obtained useful signals through de-noising and analyzing, at last, the measure results are displayed completely.In order to prove the feasibility of the designed system, we do experiment on the fluorescence fiber gas detecting system, which verified the linear relationship between fluorescence intensity and gas concentration. During data processing, we decreased the workload through using LabVIEW. At the end of the paper, system calibration experiment is done and performance of the system is analyzed.