Effect of CO2/H2O on the Incipient Ultrafine Particulate Matter Formation in Oxy-fuel Combustion of High-Sodium Lignite

Abstract

In this work, the formation of incipient ultrafine particulate matter (PM) from high-sodium lignite combustion, under both dry and wet oxy-fuel conditions, is intensively investigated using an optically accessible flat-flame burner. The ambient temperature was set at 1500 K, and measurements were performed along the zones with the coal residence time of 0–40 ms. We simultaneously introduced thermophoresis sampling, dilution sampling, and phase-selective laser-induced breakdown spectroscopy (PS-LIBS) to characterize the morphologies, components, and particle size distributions (PSDs) of ultrafine PM as well as the behaviors of Na. The results indicate that incipient particles formed in CO2–O2 ambience are more abundant in Na and Si. The substitution of CO2 may accelerate the mass loss rate of coal in the early devolatilization stage, whereas the Na-based incipient particles form around a time of ∼10 ms that is similar to conventional N2–O2 ambience. In combination with the computational fluid dynamics (CFD...