Characteristics of NOx emission from Chinese coal-fired power plants equipped with new technologies

Abstract Coal combustion in coal-fired power plants is one of the important anthropogenic NO x sources, especially in China. Many policies and methods aiming at reducing pollutants, such as increasing installed capacity and installing air pollution control devices (APCDs), especially selective catalytic reduction (SCR) units, could alter NO x emission characteristics (NO x concentration, NO 2 /NO x ratio, and NO x emission factor). This study reported the NO x characteristics of eight new coal-fired power-generating units with different boiler patterns, installed capacities, operating loads, and coal types. The results showed that larger units produced less NO x , and anthracite combustion generated more NO x than bitumite and lignite combustion. During formation, the NO x emission factors varied from 1.81 to 6.14 g/kg, much lower than those of older units at similar scales. This implies that NO x emissions of current and future units could be overestimated if they are based on outdated emission factors. In addition, APCDs, especially SCR, greatly decreased NO x emissions, but increased NO 2 /NO x ratios. Regardless, the NO 2 /NO x ratios were lower than 5%, in accordance with the guidelines and supporting the current method for calculating NO x emissions from coal-fired power plants that ignore NO 2 .