Near-Zero Air Pollutant Emission Technologies and Applications for Clean Coal-Fired Power

Abstract

Abstract Coal is the dominant energy source in China, and coal-fired power accounts for about half of coal consumption. However, air pollutant emissions from coal-fired power plants cause severe ecological and environmental problems. This paper focuses on near-zero emission technologies and applications for clean coal-fired power. The long-term operation states of near-zero emission units were evaluated, and synergistic and special mercury (Hg) control technologies were researched. The results show that the principle technical route of near-zero emission, which was applied to 101 of China’s coal-fired units, has good adaptability to coal properties. The emission concentrations of particulate matter (PM), SO2, and NOx were below the emission limits of gas-fired power plants and the compliance rates of the hourly average emission concentrations reaching near-zero emission in long-term operation exceeded 99%. With the application of near-zero emission technologies, the generating costs increased by about 0.01 CNY∙(kW∙h)–1. However, the total emissions of air pollutants decreased by about 90%, resulting in effective improvement of the ambient air quality. Furthermore, while the Hg emission concentrations of the near-zero emission units ranged from 0.51 to 2.89 μg∙m−3, after the modified fly ash (MFA) special Hg removal system was applied, Hg emission concentration reached as low as 0.29 μg∙m−3. The operating cost of this system was only 10%–15% of the cost of mainstream Hg removal technology using activated carbon injection. Based on experimental studies carried out in a 50 000 m3∙h−1 coal-fired flue gas pollutant control pilot platform, the interaction relationships of multi-pollutant removal were obtained and solutions were developed for emissions reaching different limits. A combined demonstration application for clean coal-fired power, with the new “1123” eco-friendly emission limits of 1, 10, 20 mg∙m−3, and 3 μg∙m−3, respectively, for PM, SO2, NOx, and Hg from near-zero emission coal-fired power were put forward and realized, providing engineering and technical support for the national enhanced pollution emission standards.