CFD Simulation On Combustion And Emission Characteristics Of Pyrolysis Gas Turbulent Diffusion Flame

As combustion and utilization of pyrolysis gas can replace part of fossil energy for power generation or heating,then it can make a complementary and integrated development with fossil energy.To some extent,it will be able to avoid energy waste,reduce environmental pollution,and improve energy efficiency.Therefore,aiming at three components known pyrolysis gases,the combustion and emission characteristics of pyrolysis gases under different burner structures and operating conditions was studied by applying computational fluid dynamics(CFD)method.The non-linear second moment(SSG)turbulence model in the Reynolds stress models,the discrete transfer method(DT)radiation model,the eddy dissipation model(EDM)in the general finite rate models,and the simplified mechanism of hydrocarbon combustion were used to simulate combustion and emission characteristics of pyrolysis gas..In view of the uneven distribution of high temperature areas in the combustion chamber,the study found that the uniformity of gas flow and temperature distribution can be improved by changing the swirling degree of the primary air passage blades,the swirling degree between 0.40 and 0.89 was appropriated for the reduced NO concentration and the increased combustion efficiency..Furthermore,by altering the load,excess air coefficient and primary air coefficient,the combustion and NO emission characteristics of pyrolysis gas were investigated.The results indicated that the combustion efficiency can be guaranteed to more than 99%,and the emission concentration of pollutant NO is low,when the load is maintained in the range of 20-30 kW,the excess air coefficient is in the range of 1.2 to 1.4,and the primary wind coefficient is around 0.8 to 0.9.By changing the proportion of hydrogen in the pyrolysis gas,the results show that an increase of H2 proportion will lead to elevated temperature and NO concentration,and this effect is more obvious when the ratio of combustible gas is low,compare to that the ratio of combustible gas is high.In addition,at different air-fuel equivalence ratios may generate special combustion features.In this study,when the ratio of H2/CO2 and CH4/CO2 is around 1,there is a critical point,which can ensure a low concentration of NO emission while maintaining stable flame combustion.