Effects of Wet Flue Gas Desulfurization and Wet Electrostatic Precipitators on Emission Characteristics of Particulate Matter and Its Ionic Compositions from Four 300 MW Level Ultralow Coal-Fired Power Plants

Abstract

To achieve ultralow-emission (ULE) standards, wet electrostatic precipitators (WESP) installed downstream from wet flue gas desulfurization (WFGD) have been widely used in Chinese coal-fired power plants (CFPPs). We conducted a comprehensive field test study at four 300 MW level ULE CFPPs, to explore the impact of wet clean processing (WFGD and WESP) on emission characteristics of three size fractions of particulate matter (PM: PM 2.5 , PM 10−2.5 , and PM >10 ) and their ionic compositions. All these CFPPs are installed with limestone-based/magnesium-based WFGD and followed by WESP as the end control device. Our results indicate that particle size distribution, mass concentration of PM, and ionic compositions in flue gas change significantly after passing WFGD and WESP. PM mass concentrations through WFGD are significantly affected by the relative strength between desulfur slurry scouring and flue gas carrying effects. Concentrations of ions in PM increase greatly after passing WFGD; especially, SO 4 2− in PM 2.5 , PM 10−2.5 , and PM >10 increase on average by about 1.4, 3.9, and 8.3 times, respectively. However, WESP before the stack can effectively reduce final PM emissions and their major ionic compositions. Furthermore, emission factors (kg/(t of coal)) of PM for different combinations of air pollution control devices are presented and discussed.

Direct Observation of Sulfate Explosive Growth in Wet Plumes Emitted From Typical Coal‐Fired Stationary Sources

“…An underestimated amount of ∼31.4% is attributed to direct SO 4 2− formation and the emissions from WFGD applications. In the CFPP sector, contribution underestimations of 67.6% ± 5.5% were found, owing to the widely used limestone‐WFGD systems (≥90%) in China (B. Wu et al., 2018). The CFPP sector is the largest contributor to the fine particulate SO 4 2− emissions, with a relative proportion of ∼35.1%.…”

Characteristics of Chemical Composition and Particle Size Distribution from Real Coal-fired Circulating Fluidised Bed (CFB) Boiler

“…Water-soluble ions, especially, SO4 2-, Ca 2+ , and NH4 + are significant in PM (Saarnio et al, 2014); however, water-soluble ion emissions are affected by the chemicals used in the desulphurisation and denitrification processes (Saarnio et al, 2014;Wu et al, 2018). Carbonaceous aerosols, including organic carbon (OC), and elemental carbon (EC), are ubiquitous species in the atmosphere.…”

“…Emissions from boilers have aroused great concern, as they not only produce gaseous pollutants, for instance, CO, CO2, NOx, and SO2 (Dios et al, 2013;Hussain and Luo, 2019), but also emit PM. Moreover, the characteristics of PM are different because of combustion processes transformation, such as different types of boilers, different coal burning conditions, and pollution control devices (Yi et al, 2008;Ma et al, 2017;Wu et al, 2018;Wang et al, 2019). As is understood, coal is the major energy for boiler combustion, used in different industrial applications such as electricity, industrial heat, and residential heating with characteristics of coal-fired emission sources .…”

Emission Characteristics of Hazardous Atmospheric Pollutants from Ultra-low Emission Coal-fired Industrial Boilers in China

“…The mass balance method is calculated by normalizing the concentration of each trace element for the entire process. It is widely used to investigate the EFs and removal efficiency for trace elements (Zhang et al, 2016;Zheng et al, 2017;Wu et al, 2018). In this study, based on the inlet and outlet concentration of trace elements for APCDs, the EFs and removal efficiency of trace elements were calculated by Eqs.…”

“…Several studies have conducted on emission level and removal efficiency of hazardous air pollutants from ULE and non-ULE coal-fired power plants (Zhang et al, 2008;Zheng et al, 2017). Wu et al (2018Wu et al ( , 2020 established an integrated emission factors (EFs) database of size-fractioned particulate matter (PM) for typical ULE technical routes installed in coal-fired power plant. investigated partitioning of hazardous trace elements from ULE coal-fired power plants.…”