富氢富氧调控的甲烷预混火焰结构和排放特性

Based on a single-head bluff-body and swirl model combustor, the flame structure, flame stability, and emission characteristics of premixed methane flames(CH₄/air) were studied, which were regulated by additives of H₂, O₂, and CO₂. Fraction control of the additives was conducted and flame conditions were designed for various premixed mixtures. The flame structure was measured by using the digital camera and the technology of Planar Laser-Induced Fluorescence of OH radical. The flue gas temperature and emissions of pollutants CO and NO_x were measured using the Testo340 gas analyzer. The results show that the addition of H₂ and O₂ leads to a more compact flame and enhances the combustion intensity, while the addition of CO₂ is potential to mitigate such effects, causing a more distributed flame shape and a lower combustion intensity. When the oxygen-rich combustion occurs with O₂ addition, both CO and NO_x increase significantly, which is not favorable to reduce the emission. In contrast, the H₂ addition can reduce the CO emission, while almost not affecting the NO_x emission. Simultaneously, although replacing N₂ with CO₂ can increase the CO emission, it significantly reduces the NO_x. The additives of H₂ and CO₂ exhibit complementary regulating effects, and their combination is an effective method to achieve stable and low emission combustion of methane.