Study Of Carbon Emission Detection Of Flue Gas Based On TDLAS

With the increasingly serious greenhouse effect in the world,greenhouse gas emissions have gradually become attention from countries.At present,CO₂ emissions from thermal power plants account for a large proportion of China's greenhouse gas emissions.Therefore,real-time monitoring of carbon dioxide emissions from coal-fired power plants is of great importance.Meanwhile,the national carbon emission trading market was fully launched in2017.In this context,carbon emission detection technology has attracted unprecedented attention.At present,methods of carbon emission monitoring in coal-fired power plants include Emission-Factor approach,Carbon Balance method and online monitoring.Online monitoring is an important approach of assessment and verification which provides direct access to intuitive carbon emissions data.Compared with the traditional technology,Tunable diode laser absorption spectroscopy?TDLAS?with high precision,fast response,noninvasive and real-time detecting multiple parameters etc,have very good application in various fields of CO₂ monitoring and a rapid development momentum.First,this paper introduces the basic principle of TDLAS technology,including the measurement mechanism of direct absorption method and wavelength modulation technology,sets up a tunable diode laser absorption spectrum measurement experimental platform,describes the experimental equipment and procedures.In this paper,CO₂ concentration was measured under a simulating condition of the flue at the tail of coal-fired power plants,and the main factors affecting the detection were explored.Secondly,based on the principle of avoiding the interference from other gas,CO₂absorptions near 1.58?m are selected,and the relationship between the scanning points and the spectral wavenumbers is established by using the HITRAN?High-resolution Transmission Molecular Absorption Database?database to perform Lorentz function fitting on the absorptions.The ratio of light intensity is calculated and the direct absorption is used to measure the concentration.The effects of the two methods,pure N₂ line method and peak removal method,are compared by direct absorption method,and the absorption spectrum baseline fitting method suitable for industrial field is discussed.Furthermore,under the condition of simulated temperature and CO₂ concentration from the tail flue in coal-fired power plant,direct absorption signals and second harmonic peak signals of different concentrations CO₂ and N₂ mixed gases?10%to 20%interval of 2%?are obtained.By analyzing the influence of temperature on the linewidth and line strength,the corrections of temperature change are given based on the concentration measurement formula and least square method.The model improves the reliability and stability of carbon emission measurement by absorption spectroscopy in coal-fired power plants.