Combustion Mechanism Study Of CH₄in O₂/CO₂Atmosphere

With the rapid development of economy in China, the CO2emission has exceeded the USA and ranked the first in the world. How to effectively reduce the emission is a serious problem in China. Oxyfuel combustion as a new Carbon capture technology develops quickly and has a good application prospects. Due to the different physical and chemical characteristics between CO2and N2, the combustion mechanism has changed a lot since CO2takes the place of N2in combustion, so many questions about the combustion mechanism need to be resolved.This paper studies the CH4combustion mechanism in O2/CO2atmosphere by numerical simulation and verifys the model by experiment.Firstly, build the G3detailed mechanism model with the PREMIX moduel of the Chemkin Software to simulate the CH4combustion process in O2/CO2atmosphere and study the laminar flame propagation speed, reaction path, concentration distribution of the main components and flame thickness. Conclusions are as follows:(1) the laminar flame propagation speed in O2/CO2atmosphere is one fifth in O2/N2atmosphere.(2) high CO2has a inhibitory effect on H atoms.(3) R284and R153in O2/CO2atmosphere is more important than in O2/N2atmosphere, in which R284has a positive effect on combustion, however, R153has a negative effect on combustion.(4) the main reaction pathes are the same in both atmospheres, but the contribution rate of each elementary reaction is different. The branch reaction path of CH3→CH2O is obviously different in individual atmosphere, in which the reaction path of CH3→CO can’t be ignored in O2/CO2atmosphere, in addation CH2(S)→CO is the major reaction path in O2/CO2atmosphere, but CH2(S)→CH2is the major reaction path in O2/N2atmosphere.Secondly, a reduced mechanism containes17components and39elementary reactions is contruced by GSA and PCA. The reduced mechanism is tested and verified by using PREMIX and in good agreement with the results of the detailed mechanism.At last, measuring the laminar flame propagation speed through the Bunsen burner experiment, the result of experiment is in good agreement with the result of model. The G3detailed mechanism is evaluated by uncertainty analysis, the result shows the G3detailed mechanism meets the "accuracy".