Characterization of PM Produced by Mesh-Quenching of Benzene Pool Flame

PM (particulate matter including soot) is formed in fuel rich combustion field. Fuel rich field inside a diffusion flame and fuel rich local mixture in turbulent diffusion flame are typical fields of PM formation. Further, flame quenching by low temperature wall sometimes results PM that including soot and many hydrocarbons. However characterization of PM formed in a flame quenching zone is not clarified yet even though many engineering problems are caused by flame quenching PM. In this study, to make clear the influence of flame quenching on PM, PM mass and characteristics such as size distribution and density of PM formed in metal mesh quenching process of laminar diffusion flame with benzene were measured by an electric micro-balance, a Scanning Mobility Particle Sizer (SMPS) and an electric hydrometer. When a metal mesh was inserted into a flame, it was quenched and no flame appeared in a downstream space on the mesh. Some of PM formed in the quenched flame deposited on the mesh and the other PM flowed out through the mesh. From the experimental results, it was confirmed that total formation rate of PM by mesh quenching was 3 times higher than that of normal diffusion flame (free flame). PM peak diameter in number distribution was half times smaller than that of PM exhausted from the tip of the free flame. Density of through PM that was flowing out through the mesh was lower than that of PM deposited on the mesh. It suggested that soot graphitization process was suppressed by mesh quenching. Further, both densities of through PM and deposit PM were far lower than that of PM exhausted from the free flame.