Studies on Characteristics and Formation of Soot Nanoparticles in an Ethylene/Air Inverse Diffusion Flame

Abstract

An ethylene/air inverse diffusion flame burner was assumed to generate a stable flame, and soot samples were captured at different locations around the outer edge along the height of the flame. The soot samples were then analyzed with transmission electron microscopy (TEM), gas chromatography-mass spectrometry (GC-MS), and other detection means, and a photoacoustic analyzer was introduced to detect the mass concentration of soot nanoparticles after inception based on their optical features. The results showed that the plot of soot concentration had the same tendency as the gas temperature’s, which increased first and then declined with the increase in flame height, but these two curves had two different turning points. As to the measurements of TEM, the morphology of soot particles exhibited diverse shapes and structures at different flame heights. Alkanes, cycloalkanes, olefins, benzene, anthracene, pyrene, and aromatic compounds were determined as the main components of soot by the detection of GC-MS. The soot formation process in the ethylene flame can be speculated to be ethylene pyrolysis, soot growth, and oxidation, as well as particulate coagulation.