Laboratory studies of submicron particles from coal combustion

Abstract

A laboratory investigation of the particles in the flue gases of a pulverized coal combustor has been conducted. The emphasis was on physical and chemical characterization of those particles smaller than 2 μm diameter. The number concentrations are large, on the order of 10¹⁴ particles/m³, and the mean size is small, 0.02 to 0.08 μm diameter. The particle size distribution is extremely narrow, supporting the hypothesis that the particles were formed by nucleation and then grew by coagulation. Predicted particle size distributions are in close agreement with the data. Chemical analyses of the submicron particles by particle induced x-ray emission show two distinct modes in the 0.03 to 3 μm size range. The larger particles consist of the major ash species, Al, Ca, Fe, and Si. The, smallest particles were composed of the more volatile species, Si and S, with a large amount of material not detected by PIXE. Optical absorption measurements suggest that this material was primarily carbon in the form of soot.

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