Abstract
With the implementation of ultra-low emission systems in coal-fired power plants in China, the emission of sulfur trioxide (SO3) has become an important issue in pollution control. However, systematic research and evaluation of SO3 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 SO3 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 SO3 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 SO3 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 SO3, 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.
Highlights
The intensive implementation of ultra-low emission (ULE) at coal-fired power plants (CFPPs) in China has expedited comprehensive improvements in the air pollution control, especially the reduction of particulate matter (PM), sulfur dioxide (SO2) and nitrogen oxides (NOx) (Ni et al, 2018)
We examined 148 power plants to determine whether their ULE systems enabled them to comply with various SO3 emission standards
2) CFPPs employing Route 1 complied with the 20 mg m–3 SO3 emission standard only when the coal’s sulfur content was ≤ 1.30%
Summary
The intensive implementation of ultra-low emission (ULE) at coal-fired power plants (CFPPs) in China has expedited comprehensive improvements in the air pollution control, especially the reduction of particulate matter (PM), sulfur dioxide (SO2) and nitrogen oxides (NOx) (Ni et al, 2018). Kwon et al (2016) reported that adding molybdenum to an SCR catalyst inhibited the adsorption of SO2, and adding tungsten improved the low-temperature activity of the catalyst. These two approaches, combining with controlling the catalyst wall thickness, effectively reduced the SO2/SO3 conversion rate of the SCR catalyst. The SO3 removal efficiencies of 148 sampled CFPPs adopting different ULE control routes were analyzed to evaluate whether they will meet the varied SO3 emission limits. This study proposed effective strategies and routes for SO3 control to comply with different SO3 emission limits
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have