Research On Detailed Chemical Kinetic Simulation Of PAHs Formation During Hydrocarbon Fuel Combustion Process

In recent years, with the increasing efficiency of fossil fuel and the increasing environmental protection requirement, more and more attentions have been paid on the emission of organic pollutants during combustion process, therefore, in the development of cleaning equipment it becomes particularly important to control the emission of pollutants according to a more profound understanding on the chemical reaction machanisms during the combustion process. Research on the formation, growth and oxidation of polycyclic aromatic hydrocarbons (PAHs) during the combustion of hydrocarbon fuel has always being a hot topic.In this paper, detailed simulations of chemical kinetics have been carried out for a series of C2-C4 laminar premixed flames with the latest and detailed reaction mechanisms, furthermore, computational results have been compared with experimental results. The key controlling factors duing to formation of PAHs are investigated, meanwhile, general patterns and pathways of the formation of PAHs have been obtained with sensitivity analysis and other methods, in order to develope the basis of controlling PAHs.Toward the laminar premixed methane flames with an equivalence ratio from 2.0 to 2.6, the dependencies of flame species are different with the same combustion temperature and pressure. The PAHs species are more sensitive to the flame equivalence ratio than aliphatic and aromatic species and C2H2 is least sensitive toФ. When 0 is less than 2.4, soot and PAHs levels increase with increasing equivalence ratio. For laminar premixed ethane flames with a pressure from 0.8 bar to 1 bar but the same C/O ratio and combustion temperature, although PAHs species levels increase with increasing pressure, the total amount are not strongly influenced. In addition, a reduced machenism N(30 chemical species and 42 reactions) about C3H8 flame has been obtained and the comparison of reduced one with Konnov's detailed one indicates that machenism N could be used in practical process because of it's accurate predicted results and contribution on saving time. The predicted and measured species concentrations in butane premixed flame with detailed reaction machenism indicate that H2CCCH self-combination reaction plays an important role during the formation of PAHs and the " H-abstraction-C2H2-addition(HACA)" mechanism is proved correct.For the laminar premixed ethanol to ethylene flames, compound reaction machenism M predicts the trend of PAHs mole fraction as a faction of coefficient a. Ethanol has a significant impact on the formation of PAHs and emissions. The formation of various PAHs has been reduced, but the trend do not been affected with the increase of coefficient a.For the laminar premixed acetylene flame, the ROP(rate of production) of the main reactions on A1, A2 and A3 have been calculated and it changes severely concentrated above the burner exit within 0.5-1.0 cm. The propargyl self-combination reaction is the primary route to benzene formation, while phenanthrene is formed primarily by the P2-1+C2H2=A3+H reaction.