Effect of Oxygen-Rich Combustion on Flame Propagation of Syngas in a Half-Open Pipe at Elevated Temperatures

The investigation of syngas flame propagation has great benefits for the effective use of gas turbines. This essay sets out to study the flame propagation of premixed oxygen-rich combustion (oxygen enrichment coefficient in volume Ω: 0.21, 0.27, 0.32, 0.37) of syngas (H₂:CO=2:8) in half-closed rectangular ducts at elevated temperatures (T: 300 K, 400 K, 500 K) and evaluate the effects of initial temperature and oxygen enrichment coefficient on the LBV from sensitivity analysis and kinetic analysis. This paper presents the effect of the expansion effect on laminar burning velocity for the first time, and separates the effect of the expansion effect on laminar burning velocity by a new method. Research shows that as the initial temperature goes up, the faster the exponential growth phase of the flame front velocity, the slower the slow growth phase. The smaller and earlier the maximum flame front velocity arrives, the slower the average flame speed is. As the oxygen enrichment coefficient goes up, the peak value of the flame front velocity gradually decreases. Oxygen-rich combustion and increasing initial temperature inhibit flame propagation in a half-open tube, but promote laminar burning velocity, which increases the key chemical bond and adiabatic flame temperature. The net reaction rate shows that oxygen-rich combustion mainly promotes the combustion reaction of H₂(R2). However, increasing the initial temperature mainly promoted the oxidation of CO(R29). Analysis of the reaction path showed that oxygen-rich combustion and increased initial temperature promoted the reaction of H₂ and CO with key chemical bonds, increased OH concentration, and inhibited OH cracking reaction.