Characteristics of Sub-Micron to Micron Particulate Matter Released from the Combustion of Different-Rank Pulverized Coals

Coal-fired power generation is the main cause of air pollution, and the circulating fluidized bed (CFB) boiler is the mainstream coal-burning technology at present. Therefore, it is of great significance to investigate the characteristics of particulate matter released from the CFB boiler. In this paper, lignite, bituminous coal and anthracite with the particle sizes of < 75 μm and 180~830 μm were selected and burned completely at 600℃, 700℃ and 800℃ respectively for the purpose of simulating the process of pulverized coal combustion in a CFB boiler and exploring the effects of coal rank, particle size and burning temperature on the characteristics of the released particulate matter. The results show that, under the same mass, bituminous coal combustion releases the most PM1, PM2.5 and PM10, followed by lignite and anthracite. A smaller particle size of pulverized coal and a higher burning temperature correspond to the release of more sub-micron to micron particulate matter. The emission factors of lignite and bituminous coal show a bimodal distribution, with the two peak values in the range of 0.1~0.18 μm and 3.2~10 μm, respectively. As the burning temperature increases and the particle size of pulverized coal decreases, the first peak value falls, and the second peak value shifts to a small particle size range. This study can serve as reference for diminishing the emission of sub-micron to micron particulate matter by coal-fired power plants and preventing air pollution.