某燃煤超低排放机组非常规污染物脱除

燃煤电厂非常规污染物的排放尚未引起足够的重视。为全面表征燃煤电厂非常规污染物脱除性能，针对某1 000 MW燃煤超低排放机组，分别采用FPM和CPM一体化采样系统、安大略法(OHM)、控制冷凝法、HJ 646-2013规定的有机物测试方法，系统研究了CPM、Hg、SO₃、PAHs等非常规污染物的梯级脱除特性。结果表明：100%、75%负荷时低-低温电除尘系统对CPM脱除率分别为87.15%、92.20%，湿法脱硫分别为49.65%、45.55%，不同负荷下FPM分别为3.6、4.4 mg·m⁻³，但CPM却分别达14.2、15.3 mg·m⁻³，CPM的浓度远超FPM；低-低温电除尘系统脱Hg效率为64.81%，整个系统的脱Hg效率为75.5%，Hg^p全部被脱除，剩余的是难以脱除的Hg⁰、Hg²⁺，脱除率分别为为63.01%、64.29%，Hg⁰排放浓度为5.4 μg·m⁻³，Hg²⁺排放浓度为0.5 μg·m⁻³；SCR脱硝催化剂将SO₂氧化成SO₃的转化率约为0.7%，低-低温电除尘系统可脱除88.7%的SO₃，湿法脱硫对SO₃的脱除率为29.63%，最终SO₃排放浓度为1.9 mg·m⁻³；全系统对16种PAHs脱除率达94.25%，其中，气相、固相脱除率分别为91.61%、99.27%，最终气相、固相PAHs排放浓度分别为2.39 μg·m⁻³和0.11 μg·m⁻³。现有超低排放设备对非常规污染物均有不同程度的协同脱除效果，满负荷条件下该机组CPM、Hg、SO₃、PAHs排放浓度分别为14.2 mg·m⁻³、5.9 μg·m⁻³、1.9 mg·m⁻³、2.5 μg·m⁻³，Hg的排放浓度满足火电厂大气污染物排放标准(GB 13223-2011)中30 μg·m⁻³的要求，CPM、SO₃、PAHs尚无国家强制排放标准。本研究结果可为燃煤电厂后续非常规污染物的控制提供参考。

Unconventional pollutant removal from a coal-fired ultra-low emission unit

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.