Research On Online Monitoring Of Industrial Gas Leakage Based On Open Path Spectroscopy Technology

With the deterioration of the air quality in recent years,severe air quality pollution in the north of China in winter has frequently occurred,and its impact on human beings should not be underestimated.This thesis describes the current status of industrial leakage,which has irregularities,and the scope of the impact is greater,and the impact on atmospheric pollution is more far-reaching.Among the gases that are prone to leakage in many industries,such as chlorine,sulfur dioxide,ammonia,benzene,hydrogen sulfide,carbon monoxide,and natural gas,ammonia gas is the “catalyst” that causes air pollution.Since industrial ammonia is stored as liquid ammonia,it is mainly stored in a specific area.Based on this storage feature and compared with the traditional point-type and open path measurement,the final choice is open path measurement.This thesis first introduces the optical methods that can be used for open path gas on line monitoring.The monitoring method used in this thesis is the colorimetric optical fiber ammonia sensor method.Based on the theoretical basis of the method,the ammonia storage method and actual leakage conditions are introduced.Considering that,an open path on line monitoring method for ammonia is proposed.According to the principle of differential optical absorption spectroscopy(DOAS),the monitoring technology and theoretical methods for the leakage of ammonia in industrial gases are analyzed.Secondly,a gas absorption tank designed for this thesis was designed.Using the effect of the Naland A perchlorate dye,the change of the transmittance of the ammonia gas at a wavelength of about 632.8 nm was researched experimentally.Considering the problem of the use of Nileland A perchlorate dyes in the process of use: the mixed gas must be fully mixed with the Naland A perchlorate dye after thorough mixing in the absorption tank,and the specific placement of the dye,etc.The experimental gas absorption tank was designed.Then,an experimental system was built.The optical equipment used in the optical system was introduced and the gas concentration and gas flow values in the experiment were listed.Finally,the experiment is completed by experimental system.The thesis analyzes the least-squares fitting,wavelet transform,and Gaussian fitting.According to the characteristics of the collected data: The data is a single peak spectrum,which can be seen as approximately normal distribution.Finally,a Gaussian fitting method was used.In addition,the leakage site was simulated and the flow rate of ammonia gas and nitrogen flow was randomly set.The data was collected and Gaussian fitting was used to calculate the experimental results.Comparing the experimental results with the manually calculated data,it was concluded that the data collected by Nileland A perchlorate was reliable when used in the ammonia leak test.Local leakage concentration monitoring can also be achieved when liquid ammonia leaks.Therefore,the experimental device and monitoring method can be used for on line monitoring of industrial gas leakage based on open path spectroscopy technology.