Unconventional pollutant removal from a coal-fired ultra-low emission unit
CHAI Xiaokang1,, HUANG Guohe1,,, XIE Yulei2, LI Wei1 1.College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China 2.School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
Abstract:The emission of unconventional pollutants from coal-fired power plants has not received enough attention. In order to fully characterize the removal characteristics of unconventional pollutants from coal-fired power plants, the step removal characteristics of CPM, Hg, SO3, PAHs and other abnormal pollutant from a 1 000 MW coal-fired ultra-low emission unit were systematically studied by using FPM and CPM integration sampling system, Ontario method (OHM), controlling condensate method, HJ 646-2013 unit test method. The results showed that at 100% and 75% loadings, the removal efficiencies of CPM were 87.15% and 92.20% by the low-low-temperature electric dust removal system, respectively, and wet desulfurization efficiencies were 49.65% and 45.55%, respectively. At different loadings, FPM emission concentrations were 3.6 and 4.4 mg·m?3, respectively, but CPM emission concentrations were 14.2 and 15.3 mg·m?3, the latter ones were much higher than the former ones. The Hg removal efficiency of low-low-temperature electric dust removal system was 64.81%, and the Hg removal efficiency of the whole system was 75.5%. Hgp was totally removed, and the remaining ones were Hg0 and Hg2+ being hard to remove, their removal efficiencies were 63.01% and 64.29%, respectively. The emission concentrations of Hg0 and Hg2+ were 5.4 μg·m?3 and 0.5 μg·m?3, respectively. The conversion rate of SO2 oxidized to SO3 by SCR denitration catalyst was about 0.7%. The low-low-temperature electric dust removal system could remove 88.7% SO3 in the gaseous state, the wet desulfurization could remove 29.63% SO3, the final SO3 emission concentration was 1.9 mg·m?3. The removal efficiency of 16 kinds of PAHs from the whole system reached 94.25%, of which the removal efficiencies of gas and solid phase PAHs were 91.61% and 99.27%, respectively, their corresponding emission concentrations were 2.39 and 0.11 μg·m?3, respectively. The existing ultra-low emission equipment had different levels of collaborative removal effect of unconventional pollutants, the emission concentrations of CPM, Hg, SO3 and PAHs of the unit at full loading were 14.2 mg·m?3, 5.9 μg·m?3, 1.9 mg·m?3 and 2.5 μg·m?3, respectively. The Hg emission concentration meets the standard of 30 μg·m?3 in Emission Standard for air pollutants from thermal power plants, and the national compulsory emission standard for the emission concentrations of CPM, Hg, SO3 and PAH have not yet settled. This study can provide a reference for the control of unconventional pollutants in coal-fired power plants. Key words:unconventional pollutants/ coal-fired power plant/ condensable particulate matter/ Hg/ SO3/ polycyclic aromatic hydrocarbon/ removal efficiency.
图1燃煤电厂烟气治理技术路线及测点布置图 Figure1.Technical roadmap of flue gas treatment and measuring points disposition in coal-fired power plants
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1.College of Environmental Science and Engineering, North China Electric Power University, Beijing 102206, China 2.School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China Received Date: 2020-02-07 Accepted Date: 2020-05-06 Available Online: 2020-12-08 Keywords:unconventional pollutants/ coal-fired power plant/ condensable particulate matter/ Hg/ SO3/ polycyclic aromatic hydrocarbon/ removal efficiency Abstract:The emission of unconventional pollutants from coal-fired power plants has not received enough attention. In order to fully characterize the removal characteristics of unconventional pollutants from coal-fired power plants, the step removal characteristics of CPM, Hg, SO3, PAHs and other abnormal pollutant from a 1 000 MW coal-fired ultra-low emission unit were systematically studied by using FPM and CPM integration sampling system, Ontario method (OHM), controlling condensate method, HJ 646-2013 unit test method. The results showed that at 100% and 75% loadings, the removal efficiencies of CPM were 87.15% and 92.20% by the low-low-temperature electric dust removal system, respectively, and wet desulfurization efficiencies were 49.65% and 45.55%, respectively. At different loadings, FPM emission concentrations were 3.6 and 4.4 mg·m?3, respectively, but CPM emission concentrations were 14.2 and 15.3 mg·m?3, the latter ones were much higher than the former ones. The Hg removal efficiency of low-low-temperature electric dust removal system was 64.81%, and the Hg removal efficiency of the whole system was 75.5%. Hgp was totally removed, and the remaining ones were Hg0 and Hg2+ being hard to remove, their removal efficiencies were 63.01% and 64.29%, respectively. The emission concentrations of Hg0 and Hg2+ were 5.4 μg·m?3 and 0.5 μg·m?3, respectively. The conversion rate of SO2 oxidized to SO3 by SCR denitration catalyst was about 0.7%. The low-low-temperature electric dust removal system could remove 88.7% SO3 in the gaseous state, the wet desulfurization could remove 29.63% SO3, the final SO3 emission concentration was 1.9 mg·m?3. The removal efficiency of 16 kinds of PAHs from the whole system reached 94.25%, of which the removal efficiencies of gas and solid phase PAHs were 91.61% and 99.27%, respectively, their corresponding emission concentrations were 2.39 and 0.11 μg·m?3, respectively. The existing ultra-low emission equipment had different levels of collaborative removal effect of unconventional pollutants, the emission concentrations of CPM, Hg, SO3 and PAHs of the unit at full loading were 14.2 mg·m?3, 5.9 μg·m?3, 1.9 mg·m?3 and 2.5 μg·m?3, respectively. The Hg emission concentration meets the standard of 30 μg·m?3 in Emission Standard for air pollutants from thermal power plants, and the national compulsory emission standard for the emission concentrations of CPM, Hg, SO3 and PAH have not yet settled. This study can provide a reference for the control of unconventional pollutants in coal-fired power plants.