Study On Sooting Tendency Of Laminar Diffusion Flame With Oxygenated-aromatic Alternative Fuels

To deal with the energy crisis and environmental pollution,the development and utilization of new energy and the discharge of pollutants after treatment are the focuses of current research.Lignin is an important source of the second generation of biomass fuel.Anisole and benzyl alcohol,two kinds of oxygenated aromatic compounds,can be obtained from the lignin pyrolysis process.These two substances are used in the combustion systems.In addition to curbing the generation of pollutants from the root,Exhaust Gas Recirculation（EGR）and other measures can also be used to reduce the emission of pollutants.The main components of EGR are N₂ and CO₂.Studying the sooting tendency of biomass fuel in a diluted environment is helpful to the further research and application of biomass fuel,and to establish the basis for solving the energy crisis and environmental pollution.In order to explore the soot characteristics of anisole and benzyl alcohol,n-heptane with a similar cetane number to diesel oil was used as base fuel in this study.Anisole and benzyl alcohol were mixed with n-heptane respectively to quantitatively analyze the sooting tendency of blended fuels by LII and LOSA.The experimental results of n-heptane showed that the soot formation of n-heptane increased with the increase of fuel flow rate,and the flame height and soot area were linearly related to the fuel flow rate.However,the soot formation,flame height and soot area decreased with the increase of air flow rate.The soot generation decreased with the increase of carrier gas flow rate,the flame would be lift-off when the carrier gas flow rate was too high.When anisole and benzyl alcohol were mixed into n-heptane respectively,the mixing of two kinds of biomass fuels promoted the sooting tendency.The flame height and soot area increased with the increase of the proportion of anisole.On the contrary,the flame height and soot area decreased with the increase of the mixture ratio of benzyl alcohol.Moreover,it was found that the flame performance of benzyl alcohol mixed fuel is extremely unstable under high pressure,while the flames of n-heptane and n-heptane/anisole showed different pressure dependence.Dilution experiments of three fuels were carried out and the results showed that the inhibition of CO₂ on soot was stronger than that of N₂.The results also showed that the inhibitive effect of the two dilution gases on soot formation in blended fuels was stronger than that in n-heptane fuel.In addition,it was found that the increase of pressure weakened the inhibitive effect of dilution gas on soot formation.