Infrared Detection System Design Of SO_ 2 Concentration Based On Filter Correlation Technology

With the rapid development of industrialization,the environmental pollution has become an urgent problem in recent years. Our country is a coal-fired power,the environment is deeply affected by the sulfur dioxide emissions,sulfur dioxide has become one of the main pollutants in the atmospheric environment. In order to control the sulfur dioxide pollution,It is important to find out a effective method to measure the concentration of sulfur dioxide in the air. Based on the consultation of domestic and foreign literature,the infrared detection methods of measuring sulfur dioxide concentration are analyzed,a detection system of measuring the sulfur dioxide concentration is designed.Firstly,several common infrared detection methods are summarized,domestic and foreign research status and development trends of the filter correlation technology are reviewed,and the gas molecular spectroscopy theory,the principle of self-correlation and mutual correlation are analyzed,the Lambert-Beer law is described briefly and filter correlation theory is elaborated in detail,which are the theoretical foundation of the filter correlation technology system design.Secondly,the selection and characteristics of IR source,photoelectric detector,reflective optocoupler,IR window and brushless DC motor are introduced in the filter correlation system design,which influence the parameters of SO2 concentration measurement system. According to filter correlation technology theory,a wheel structure is designed. Combining the correlation technology,the extraction,amplification and filter for the measuring signals are realized. Switch circuit,phase shifting circuit and differential circuit are designed and analyzed reasonably.Finally,the measurement experiment of system for sulfur dioxide concentration has been studied and analyzed under the existing experimental condition. we have made measurement experiment for different SO2 concentration and the same SO2 concentration repeatability and measurement system stability. It demonstrated that detection system design for SO2 concentration based on the filter correlation technology and infrared theory is feasible through the experimental results.