| dc.description.abstract | In this study, a mercury sampling method based on US EPA Method 30B, including the sampling process, the operation of sampling equipment and the QA/QC of sampling and analysis is developed. A survey of mercury emissions and distribution in the flue gas of stacks a coal-fired power plant in Taiwan is conducted in three seasons. In addition, the results obtained by US EPA Method 30B were compared with that obtained with the Continuous Emissions Monitoring Systems (CEMS). The results show that the sampling and analysis method of US EPA Method 30B and its QA/QC have been fully established and the difference between US EPA Method 30B and mercury CEMS data does not exceed 1.0 µg/scm. Mercury concentrations emitted from a large-scale coal fired power plant ranged from 0.04 to 0.346 µg/Nm3, which are lower than the emission standards enacted by Taiwan EPA (2 µg/Nm3). To verify that US EPA Method 30B is feasible as a reference method for Relative Accuracy Test Audits (RATA) of mercury CEMS, this research also analyzes the solid and liquid samples discharged by air pollution control devices. For solid samples, the mercury concentrations of coals in three seasons range from 0.031 to 0.057 mg/kg; the bottom ashes are below the method detection limit (MDL) except for the boiler No. 2 in season Ⅲ (0.01 mg/kg). The mercury concentrations of fly ashes are between 0.075 ~ 0.712 mg/kg. The relative enrichment factor of fly ash is much higher than that of bottom ash. For liquid samples, the mercury concentrations of desulfurized seawater in each season range from 0.057 to 1.190 µg/L, and the mercury concentration of influent seawater in season Ⅲ is 0.029 µg/L. The emission factors of the stacks in each season range from 0.37 to 3.37 mg Hg/t coal, which meets the mercury emission standards for coal-fired power plants in the US MATS. Moreover, the influence of hydrogen chloride (HCl) in the flue gas on the oxidation of mercury is also an important key. Thus, this research also conducts experiments and discusses the mercury oxidation efficiency of commercial SCR catalysts and the influence of HCl. The results show that at low concentrations (5.5 to 6.0 µg/Nm3), mercury is strongly adsorbed on commercial SCR catalyst even at 370oC. The addition of HCl, especially at 20 ppm and 30 ppm, can effectively increase mercury oxidation efficiency (80% to 90%). | en_US |