Atmospheric Lead Emissions from Coal-Fired Power Plants with Different Boilers and APCDs in Guizhou, Southwest China

Lead (Pb) emissions into the atmosphere from anthropogenic sources have attracted considerable attention due to lead's high toxicity and associated human health and environmental impacts. Pb emission inventories need to be updated considering the development of modern industry as well as the transformation and upgrading of industrial equipment in recent years. Coal-fired power plants (CFPPs) have been an important source of atmospheric Pb emission in China since the late 1990s, while tremendous advantages have been achieved in the air-pollution control devices (APCDs) in the most recent two decades. In this study, Pb emissions from eight CFPPs, two of which have circulating fluidized bed boilers (CFB) and the others have pulverized coal fired boilers (PC), in Guizhou province, Southwest China were investigated. Solid samples including feed fuel (coal, gangue, and coal slime), limestone, bottom ash, fly ash, and gypsum, as well as stack flue gas samples were simultaneously collected for determining the internal partitioning behavior and the atmospheric emissions of Pb from these CFPPs. Pb concentrations of feed coal, limestone, bottom ash, fly ash, gypsum, and stack flue gas were in the range of 10.17-30.94, 0.36-3.08, 7.75-27.10, 33.56-73.16, 0.34-2.18 mg.kg(-1), and 0.33-1.58 mu g-Nm(-3), respectively. The mass balance (output/input) ratio of Pb was in the range of 83.73-124.95%, with input dominated by the feed coal (95.89-99.96%) and output by fly ash (73.17-97.54%), followed by bottom ash (2.16-26.76%) and atmospheric emissions (0.01-0.08%). More Pb ended up in PC fly ash (88.89-97.54%) than CFB fly ash (73.17-81.19%), but an opposite trend was found in the bottom ash for different boilers. Pb emission factors (EMFs) could not be differentiated significantly between PC and CFB boilers, which were in the range of 2.32-10.67 mg.t(-1) fuel, 1.28-6.51 mu g.(kW.h)(-1), or 0.12-0.51 g.TJ(-1). Atmospheric Pb emissions from Guizhou's CFPP were estimated to be 430 +/- 163 kg.y(-1) in 2017, much lower than previously reported values.