Fate of cadmium in coal-fired power plants in Guizhou, Southwest China:With emphasis on updated atmospheric emissions

Özet

Coal-fired power plants (CFPPs) are important source of anthropogenic atmospheric releases of various pollu-tants, including cadmium (Cd). In this research, the distribution of Cd in seven CFPPs in Guizhou province,southwest China and the atmospheric Cd emissions from this source category in this province was studied.Among the boilers, one was a circulatingfluidized bed boiler (CFB) and the others were pulverized coal-firedboilers (PC). All CFPPs are equipped with De-NOx, De-dust, and De-SO2devices. Solid samples including feedfuel (coal, gangue, and coal slime), limestone, bottom ash,fly ash, gypsum, as well as stackflue gas samples weresimultaneously collected and analyzed. Cd in feed coal, bottom ash,fly ash, limestone, gypsum, and stackfluegas were in the range of 0.15–0.68, 0.08–0.42, 0.43–2.03, 0.01–0.67, 0.02–0.41 mg kg−1, and0.005–0.03μg·Nm−3, respectively. Cd release ratio during the coal combustion in the boiler was in the range of95.91–98.77% for PC, but only 76.94% for CFB. Cd atmospheric emission factors were in the range of0.03–0.2 mg Cd·t−1coal, 0.02–0.1μg·(kW·h)−1or 0.002–0.01 g Cd·TJ−1for the seven CFPPs, lower values werefound for CFB boiler than that of PC boilers. In 2017, the amount of Cd emitted from CFPPs in Guizhou provincewas estimated to be 51.4 kg y−1(CFB: 2.4 kg y−1and PC: 49 ± 32 kg y−1), significantly lower than previousreports.