An Investigation of SO_3 Control Routes in Ultra-low Emission Coal-fired Power Plants
Yang Zhang；Chenghang Zheng；Shaojun Liu；Ruiyang Qu；Yonglong Yang；Haitao Zhao；Zhengda Yang；Yue Zhu；Xiang Gao
Coal-fired power plants ； Ultra-low emission ； SO_3 emission ； Control route ； Synergistic removal
Aerosol and Air Quality Research
|Volume or Term/Year and Month of Publication||
19卷12期（2019 / 12 / 01）
2908 - 2916
With the implementation of ultra-low emission systems in coal-fired power plants in China, the emission of sulfur trioxide (SO_3) has become an important issue in pollution control. However, systematic research and evaluation of SO_3 control routes based on the existing ultra-low emission systems are still lacking. We assigned 148 coal-fired power plants to four categories based on their ultra-low emission control routes and selected a representative power plant from each category for comprehensive field testing. The results indicated great variability in the synergistic SO_3 removal capability of different air pollution control devices and routes, resulting in removal efficiencies that ranged from 27% to 94%. Control Route 1, which lacked both a low-low temperature electrostatic precipitator (LLTESP) and a wet electrostatic precipitator (WESP), exhibited the lowest removal efficiency. The two routes equipped with either an LLTESP or a WESP (Control Routes 2 and 3) reduced the SO_3 concentration in the flue gas produced by medium-sulfur-coal combustion to below 10 mg m^(-3), whereas Control Route 4, which utilized both an LLTESP and a WESP, reduced the SO_3 concentration to below 5 mg m^(-3). Furthermore, sampling the emissions of the 148 power plants revealed that only 14% of the power plants complied with the 5 mg m^(-3) standard for SO_3, although 44% and 64% of them complied with the 10 mg m^(-3) and the 20 mg m^(-3) standard, respectively. Our study evaluated the control routes within the context of the whole process, which can guide subsequent research and engineering practices.