Development Of Gaseous Methyl Mercaptan Analyzer Based On Tunable Laser Absorption Spectroscopy

Methyl mercaptan?CH₃SH?is a common toxic gas with an extremely repulsive smell.Methyl mercaptan is a production of both industrial and agricultural activities,and it is also a metabolic byproduct.The awful smell of methyl mercaptan not only affect our life quality,but also harm our health.In order to control environmental pollution problem and guarantee safety production,it is urgent to develop a methyl mercaptan monitoring instrument with a high precision and high sensitivity to monitor methyl mercaptan online,in situ and in real time.Firstly,the analysis of methyl mercaptan absorption spectrum.In order to monitor methyl mercaptan specifically,it was necessary to determine the optimal absorption line which can avoid the disturbance of the other gases.Therefore,the paper analyzed the absorption peaks according to the basic vibration,as well as disturbance from atmospheric components and other hydrocarbons in the actual monitoring environment.Secondly,the design of the laser based gaseous methyl mercaptan analyzer.According to the analyzer`s technical parameters,a overall scheme of the analyzer is designed.Besides,the function and structure of the analyzer`s main modules are introduced,the communication interfaces are designed as well.Finally,data processing and wavelength calibration are also discussed in this paper.Thirdly,calibration,performance test and evaluation of the analyzer.The paper analyzed the calibration process and result,as well as the performance test process and result.The result of methyl mercaptan concentration gradient experiment was used to evaluate the analyzer`s linearity.Allan variance was used to evaluate the analyzer`s detection limit and optimal integral time.The sources of the analyzer`s measurement uncertainty were also discussed.The gaseous methyl mercaptan analyzer developed in the paper benefit high sensitivity and specific detecting ability,and overcome the shortcomings of some traditional detection methods,which were easy to aging,complex operation,cross detecting and so on.The analyzer can meet the requirement of real time and online methyl mercaptan monitoring in industrial exhaust emissions.