Study On The Release Characteristics Of Alkali Metals In The Combustion Process Of Single Particle Solid Fuel Based On Spontaneous Emission Spectroscopy

Coal and biomass are important energy sources,which are mainly used by combustion.However,the release of compounds such as alkali metals?Na,K?contained in coal and biomass into the gas phase during combustion is likely to cause problems such as high-temperature corrosion,heating surface scaling,and slagging in the furnace.In addition,the physical properties of biomass and coal fuel and the content and occurrence form of alkali metals are different.Therefore,it is necessary to deeply study the real-time dynamic law of the release of alkali metal during the combustion of solid fuel,so as to provide a basis for revealing the release mechanism of alkali metal during the combustion process.In this study,the CO₂laser was used as the ignition heat source,and the whole process of single particle solid fuel combustion was taken as the research object.An experimental platform for the research on the release characteristics of alkali metals based on spontaneous radiation was constructed.Firstly,the ICCD spectrometer was used to directly collect the spontaneous emission spectrum of the flame of different solid fuels?eucalyptus,bagasse,and coal?during the combustion process,and the real-time information of the alkali metal release process of different fuel combustion processes was obtained.And the spatial and temporal distribution characteristics of alkali metals K and Na were analyzed in different atmospheres..The results show that,the peak of alkali metal?K?release spectrum from biomass fuel is larger,and the peak of alkali metal release spectrum from coal is the smallest.At the beginning of the combustion,the height of the flame and the maximum position of K spectrum intensity are:coal<eucalyptus<bagasse,and the height of the maximum position of K spectrum intensity coincides with the height of the center of the flame in spatiotemporal distribution.In O₂/CO₂atmosphere,the spatiotemporal distribution of K atom spectrum intensity during the burning process of eucalyptus and bagasse is more uniform than that in the O₂/N₂atmosphere,and the difference in the spatiotemporal distribution of the two biomasses becomes smaller.The release time of K atoms during coal combustion is longer,and the flame height decreases more slowly.Compared with biomass,the time for the alkali metal release of coal increases more.Furthermore,as the concentration of CO₂increases,the total intensity of alkali metal spectrum decreases,and the total intensity of alkali metal spectrum of biomass decreases more than coal.Moreover,in order to analyze the law of alkali metal release during the combustion of different forms of alkali metals,on the one hand,the effects of different contents and different forms of potassium?KCl and K₂CO₃?on the fuel ignition were analyzed by flame images.On the other hand,the effect on the alkali metal release during the combustion process was analyzed in combination with a fiber optic spectrometer.The results showed that,when different forms of potassium are added to coal,the ignition time of the gas phase is delayed,and the ignition delay of K₂CO₃is later than that of KCl.At the same potassium content,the atomic spectral intensity of K and Na added with KCl is stronger than that with K₂CO₃.However,when the content of K added is high?3.5%K?,the difference between the additives is small.And in the initial stage of volatile combustion,CO₂instead of N₂has a stronger inhibitory effect on K atom release in KCl adding samples than K₂CO₃,and as the combustion progresses,the inhibitory effects of CO₂on different forms of alkali metals show opposite effects.Finally,the thesis is summarized and the next step is prospected.