Number Size Distribution of Particles Emitted from Two Kinds of Typical Boilers in a Coal-Fired Power Plant in China

Ultrafine particles (Dp < 100 nm) are suspected to have considerably stronger impacts on human health in recent studies, and the coal-fired power plants are one of the major anthropogenic sources of the ultrafine particles. In order to characterize the ultraline particles emitted from power plants, comprehensive field research on the number size distribution for boilers with and without low NOx burners (LNBs) was conducted online in a pulverized coal-fired power plant in China. With the use of an engine exhaust particle sizer (EEPS) and an aerodynamic particle sizer (APS), the lower limit of particles measured is extended to 5.6 nm. The particle number concentrations decrease with increasing size, and the nucleation mode particles are dominant in the number concentration. Additionally, the size distributions for boilers with or without LNBs are compared. Results show that the concentrations of ultrafine particles are notably higher for the boiler with LNBs than those for the boiler without LNBs. In addition, the shapes of particle size distributions (PSDs) for the two boilers are quite different in the PSDs measured with the EEPS but uniform in the PSDs measured by the APS. This suggests that LNBs favor the formation of fine particles, which should be considered in the emission control measures of coal-fired power plants.