Experimental Study on Lower Flammability Limits of CO2/N2 Diluted Syngas

The lower flammability limits of syngas/air mixtures with CO2 and N2 inert dilution were experimentally studied under atmospheric conditions via a self-developed closed cylindrical stainless steel vessel. The experimental data were used to validate the performance of the Le Chatelier's Rule. The experimental results showed that, the lower flammability limit of fuels mixtures decreases with the increase of H2 fraction. A small amount of H2 in the fuels presents the significant effect on the lower flammability limit of mixtures due to the variation of the controlled mechanism of the reaction. The lower flammability limits of mixtures almost linearly increases with an increase in inert dilution ratio. CO2 has a stronger inert effect than N2 due to CO2's stronger thermal and chemical kinetic effect in reducing the flame temperature and radical concentrations. The prediction by Le Chatelier's Rule has great discrepancy against the experimental results when H2 fraction is small or with the high presence of inert species in the mixture. Moreover, the different inter effect between CO2 and N2 on the lower flammability limit cannot be calculated using Le Chatelier's Rule. © 2019, Editorial Department of Journal of Northeastern University. All right reserved.