Arsenic emission and distribution characteristics in the ultra-low emission coal-fired power plant

The characteristics of arsenic emission and distribution of a typical Chinese coal-fired power plant renovated with ultra-low emission technique have been studied. The results showed that arsenic concentration in coal was 5.72 mg/kg, and the arsenic emissions in fly ash, bottom ash, gypsum, flue gas, and wastewater were 489.12 g/h, 5.15 g/h, 1.14 g/h, 0.46 g/h, and 0.03 g/h, respectively, corresponding to the proportion of arsenic in fly ash, bottom ash, gypsum, flue gas, and wastewater of 98.63%, 1.04%, 0.23%, 0.09%, and 0.01%, respectively. About 87.61% of the gaseous arsenic was absorbed by catalysts used for selective catalytic reduction (SCR). Low-low temperature electrostatic precipitator (LLT-ESP) plays a key role in decreasing particulate arsenic. Wet flue gas desulfurization (WFGD) has positive effects on absorbing both gaseous and particulate arsenic. The removal efficiencies across the air pollution control devices follow the order of LLT-ESP > WFGD > SCR. The LLT-ESP can achieve a significant arsenic removal efficiency of 99.94%, resulting in quite low arsenic emission to the atmosphere. According to the calculated arsenic emission factor, the total emission amount of arsenic to the atmosphere from all Chinese coal-fired stations with ultra-low emission control technique in 2020 is estimated to be about 9.67-11.59 tons/year.

Automated summary

This study investigates the characteristics of arsenic emissions and distribution in a typical Chinese coal-fired power plant renovated with ultra-low emission techniques. The results show that arsenic is mainly emitted in fly ash and can be efficiently absorbed and removed by air pollution control devices. Low-low temperature electrostatic precipitator, wet flue gas desulfurization, and selective catalytic reduction play important roles in reducing arsenic emissions. Overall, the ultra-low emission control technique has a significant effect on reducing arsenic emissions.