Influence of mineral transformation on emission of particulate matters during coal combustion

Abstract

Combustion of pulverized coal was studied in a drop tube furnace to understand coal mineral properties with the emission of particulate matters (PM). Experimental conditions were selected as follows: coal particle size was smaller than 63 μm; reaction temperature was 1 100vH, 1 250vH and 1 400vH respectively; oxygen content was 20% and 50% respectively. PM was collected with a 13-stagelow pressure impactor (LPI) having an aerodynamic cut-off diameter ranging from 10.0 μm to 0.03 μm for a size-segregated collection. Such properties as concentration, particle size distribution and elemental composition of PM were investigated. The experimental results indicate that the emitted PM has a bimodal distribution having two peaks around 4.0 μm and 0.1 μm. Increasing temperature leads to the formation of more PM; varied oxygen content leads to much change of emitted PM. PM was also subjected to XRF analysis to quantify the elemental composition. The results show that PM of 0.1 μm is rich in sulfates. Meanwhile, SiO₂ and Al₂O₃ are prevalent in PM of 4.0 μm, which means that the last peak around 4.0 μm is mainly aluminosilicate salts.

Keywords

coal combustion, particulate matters, particle size distribution, mineral, chemical species