Experimental And Numerical Simulation Research On The Dilution And Diffusion Combustion Of H₂/CO Syngas

Syngas is the intermediate product of coal or/and biomass gasification with environmental friendliness,which contains H2,CO,N2,CO2,H2O,CH4 and other hydrocarbons.The composition of syngas is variable due to the different raw materials used for gasification.The combustion and emission characteristics of a syngas flame vary widely with the composition of syngas.The main combustible components of syngas are H2 and CO.Syngas is a clean gaseous fuel without particulates or corrosive components such as chlorides and sulfides because these contaminants have been removed in the process of gasification.But few domestic researches involves in this field.Based on this background,NO formation and flame characteristics in laminar coflow H2/CO syngas diffusion flames were experimentally and numerically investigated in this study.The paper consists of the following parts:The system of the axisymmetric syngas coflow diffusion flame is set up and the effect of H2/CO ratio and dilution addition in different concentration on NO formation in an axisymmetric syngas coflow diffusion flame is investigated by experiment.The numerical model of the axisymmetric syngas coflow diffusion flame was completed for computing the temperatures,the concentrations of radicals and NO emission index,and the effect of pressure was also investigated.Under the same conditions,good agreement between the simulation results and the experimental data is reached.The results indicate that NO formation increases with the H2/CO ratio in syngas coflow flame,and the peak flame temperature and NO formation increases obviously with the increase of pressure.For diluted flame,CO2/N2/CH4 dilution can reduce the peak temperature of syngas flame and the ability to reduce peak flame temperature is decreased in the following order:CO2>N2>CH4.CO2/N2 dilution can reduce the NO formation in syngas flame while CH4 dilution promotes the NO formation.