Research On Trace Gas Detection And Temperature Measurement For Combustion Field Based On TDLAS Technique

Trace gas technology can detect flammable and toxic gases to prevent the generation of danger,so it has been widely used in the industrial field.It can also determine the combustion state by measuring the concentration of combustion products and the temperature of combustion field.Since non-contact measurement,high sensitivity,high spectral resolution,fast response speed and low price,TDLAS is widely used in trace gas detection and combustion diagnosis.First of all,this paper studied the related theories of TDLAS technology,mainly introduced the basic theory of gas absorption,and studied the linear function of gas absorption spectrum line.On this basis,it studied the measurement method of trace gas concentration and combustion field temperature measurement method.Secondly,the concentration detection research based on TDLAS technology took C₂H₂ and CO as the target to detect gas,used the gas absorption pool to increase the length of the absorption light path,and used semiconductor laser and quantum cascade laser as the light source,respectively,to compare the absorption effect of gas in near-infrared band and mid-infrared band.On the basis of concentration detection,H₂O was taken as the target to detect gas,and temperature inversion was carried out by using dual-line temperature measurement method.Firstly,a CH₄/Air premix plane flame combustion system was built,and the temperature at different positions of the plane flame was measured respectively.It was found that the temperature was in the range of 2000?2200K when the flame was fully burned.Then a C₂H₅OH/Air combustion system was built.The temperature at the bottom of the flame was measured and calibrated by thermocouple,and the temperature was found to be about 1000 K.Then,as a result of the experiment system was affected by environment and instruments,there were some noise in the measurement signal interference,so noise sources were analyzed,at the same time for the noise suppression,this paper taked the wavelet threshold denoising,the time-frequency peak filtering de-noising,four kinds of singular value decomposition and moving average filtering algorithm for measuring signal in noise suppression processing,The filtering effects of the four algorithms were compared.Finally,the paper is summarized,the advantages and disadvantages were analyzed,and future research directions are pointed out.