Application Research Of TDLAS Technology In NO_x Concentration Measurement Of Diesel Engine Emission

Due to the advantages of quick start,good economy and high reliability,diesel engine has occupied a dominant position in the marine power plant since its inception.With the continuous development of ship industry,the proportion of pollutants discharged from ships in air pollution is increasing year by year.NO_X,as the most harmful component of pollutants discharged from ships,has been widely concerned.In order to reduce the air pollution caused by ships,the requirements of various laws and regulations for NO_Xemission of marine diesel engines are increasingly stringent.At the same time,high requirements are put forward for the accuracy,dynamic response characteristics and system mobility of NO_Xcomponent detection technology of marine diesel engines.The traditional testing instruments are bulky,the testing process is tedious and the mobility is poor,which can not meet the requirements of real-time emission monitoring in the process of ship operation.In view of the above problems,this paper studies the application of TDLAS technology in the measurement of NO_Xconcentration of diesel engine,aiming to realize the real-time online monitoring of NO_Xconcentration.Firstly,the existing problems of marine diesel engine emission testing technology are analyzed,and the feasibility of TDLAS technology used in marine diesel engine emission online monitoring is demonstrated.In this paper,the mechanism of spectral absorption technology is studied,and the influence of environment on the test results is considered in combination with the actual characteristics of marine diesel engine emissions.According to the characteristics of environmental parameters fluctuation,the corresponding correction methods are proposed.Then,a concentration measurement model of direct measurement and harmonic measurement based on TDLAS technology is built in Simulink.NO is selected as the target gas for simulation analysis.The effects of temperature,pressure,modulation signal and other parameters on concentration measurement are simulated.The simulation results have certain reference value for the development of TDLAS measurement system.Finally,a measurement system of marine diesel engine emission components based on TDLAS technology is designed.The direct measurement method and the harmonic measurement method were used to carry out the experimental research on YC6K420LN-C31dual fuel marine engine,and compared with the emission analyzer of AVL company,the better experimental results were obtained.Through the work carried out in this paper,it is confirmed that the marine emission pollutant testing technology based on TDLAS technology can meet the requirements of high precision,good real-time performance,fast response speed,multi-component measurement,etc.,which can provide strong support for fault diagnosis and intelligent control of marine diesel engine.