Effect of External Mineral Addition on PM Generated from Zhundong Coal Combustion

Abstract

The effect of intrinsic metal mineral elements in the combustion process of pulverized coal on the formation and transformation mechanism of PM was investigated in a drop-tube furnace in air atmospheres at 1200 °C, which laid a solid foundation for the control of particulate pollutants. The results show that reducing the evaporation of mineral elements or the generated PM1 aggregating to form PM1–10 or particles bigger than 10µm can reduce the emission of PM1 in the coal combustion process. The amount of PM0.2, PM0.2–1, PM1–2.5 and PM2.5 produced by the raw coal-carrying Mg are reduced by 36.7%, 17.4%, 24.6% and 21.6%, respectively. The amount of PM10 is almost unchanged. The addition of Mg increases the viscosity of submicron particles effectively, making it easier to aggregate and bond together to form ultra-micron particles. The amount of PM0.2, PM0.2–1, PM1–2.5, PM2.5 and PM10 produced by the raw coal-carrying Ca are reduced by 36.3%, 33.0%, 42.8%, 38% and 17.7%, respectively. The effect of adding Ca compounds on the particles is better than that of Mg. The amount of PM0.2, PM0.2–1, PM1–2.5, PM2.5 and PM10 produced by the raw coal-carrying Fe are reduced by 15.6%, 16.2%, 31.1%, 22.4% and 5%, respectively. While the production of PM2.5–10 increased from 0.17 mg/g to 0.34 mg/g, it is clear that a significant fraction of the submicron particles produced during the combustion of the raw coal-carrying Fe are transformed into ultra-micron particles. After comparing the particulate matter produced by raw coal-carrying Mg, Ca and Fe, it shows that the addition of these three elements can effectively reduce the ash melting point, so that during the process of coal combustion, part of the sub-micron are transformed into ultra-micron particles, which are easy to remove.