超低排放燃煤电厂低低温电除尘器协同脱汞研究
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摘要
通过调整某660 MW超低排放燃煤电厂低低温省煤器烟气温度,测试了煤中汞质量分数和电除尘器出入口烟气中各形态汞的质量浓度,分析了不同烟气温度下汞形态的变化特征。结果表明:低低温省煤器烟气温度会影响汞的形态分布,烟气温度降低时Hg~0向Hg~(2+)或Hg_p转变;低低温电除尘对Hg~0和Hg~(2+)具有协同脱除作用;低低温省煤器出口烟气温度为90℃时,低低温电除尘器入口Hg~(2+)和Hg_p的质量分数最高,低低温电除尘器总汞脱除率为84.4%,出口烟气中Hg~0和Hg~(2+)的质量浓度最低,此工况下低低温电除尘器对汞的协同脱除效果最佳;低低温省煤器停运时,低低温电除尘器出口烟气Hg~0和Hg~(2+)的质量浓度高于其他工况。
By adjusting the flue gas temperature of low-low temperature economizer in a 660 MW ultra-low emission coal-fired power plant, the mercury content in coal and the mercury concentration of different species in flue gas at inlet and outlet of the electrostatic precipitator(ESP) were measured, so as to study the variation characteristics of mercury speciation in the flue gas under different working conditions. Results show that the flue gas temperature in low-low temperature economizer would affect the distribution of mercury speciation, and when the flue gas temperature drops, the elemental mercury turns into oxidized mercury and particulate mercury. The low-low temperature ESP has a synergistic effect on the removal of both gaseous elemental mercury and oxidized mercury. When the outlet flue gas temperature of low-low temperature economizer is 90 ℃, the shares of elemental mercury and particulate mercury are the highest at the inlet of low-low temperature ESP, while the mass concentrations of elemental mercury and oxidized mercury are the lowest in the outlet flue gas, indicating an optimal effect of low-low temperature ESP on the removal of mercury, with a removal efficiency reaching 84.4%. The mass concentrations of gaseous elemental mercury and oxidized mercury in the outlet flue gas of low-low temperature ESP are higher than other working conditions when the low-low temperature economizer is out of service.
By adjusting the flue gas temperature of low-low temperature economizer in a 660 MW ultra-low emission coal-fired power plant, the mercury content in coal and the mercury concentration of different species in flue gas at inlet and outlet of the electrostatic precipitator(ESP) were measured, so as to study the variation characteristics of mercury speciation in the flue gas under different working conditions. Results show that the flue gas temperature in low-low temperature economizer would affect the distribution of mercury speciation, and when the flue gas temperature drops, the elemental mercury turns into oxidized mercury and particulate mercury. The low-low temperature ESP has a synergistic effect on the removal of both gaseous elemental mercury and oxidized mercury. When the outlet flue gas temperature of low-low temperature economizer is 90 ℃, the shares of elemental mercury and particulate mercury are the highest at the inlet of low-low temperature ESP, while the mass concentrations of elemental mercury and oxidized mercury are the lowest in the outlet flue gas, indicating an optimal effect of low-low temperature ESP on the removal of mercury, with a removal efficiency reaching 84.4%. The mass concentrations of gaseous elemental mercury and oxidized mercury in the outlet flue gas of low-low temperature ESP are higher than other working conditions when the low-low temperature economizer is out of service.
引文
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[18] 刘含笑,姚宇平,郦建国,等.低低温条件下飞灰工况比电阻特性[J].洁净煤技术,2017,23(5):125-128.LIU Hanxiao,YAO Yuping,LI Jianguo,et al.Resistivity characteristics of fly ash under low-low temperature[J].Clean Coal Technology,2017,23(5):125-128.
[2] WU Ye,WANG Shuxiao,STREETS D G,et al.Trends in anthropogenic mercury emissions in China from 1995 to 2003[J].Environmental Science & Technology,2006,40(17):5312-5318.
[3] 吴晓云,郑有飞,林克思.我国大气环境中汞污染现状[J].中国环境科学,2015,35(9):2623-2635.WU Xiaoyun,ZHENG Youfei,LIN Kesi.Chinese atmospheric mercury pollution status[J].China Environmental Science,2015,35(9):2623-2635.
[4] TANG Nian,PAN Siwei.Study on mercury emission and migration from large-scale pulverized coal fired boilers[J].Journal of Fuel Chemistry and Technology,2013,41(4):484-490.
[5] 英国石油集团公司.BP世界能源统计年鉴2017[EB/OL].(2017-07-05)[2018-12-26].http://www.bp.com/content/dam/bp-country/zh_cn/Publications/StatsReview2017/2017版《BP世界能源统计年鉴》中国专题.
[6] 熊桂龙,李水清,陈晟,等.增强PM2.5脱除的新型电除尘技术的发展[J].中国电机工程学报,2015,35(9):2217-2223.XIONG Guilong,LI Shuiqing,CHEN Sheng,et al.Development of advanced electrostatic precipitation technologies for reducing PM2.5 emissions from coal-fired power plants[J].Proceedings of the CSEE,2015,35(9):2217-2223.
[7] 容銮恩,袁镇福,刘志敏,等.电站锅炉原理[M].北京:中国电力出版社,2010:89-95.
[8] NAKAYAMA Y,NAKAMURA S,TAKEUCHI Y,et al.MHI high efficiency system-proven technology for multipollutant removal[R].Japan:[s.n.],2011.
[9] 靳星.静电除尘器内细颗粒物脱除特性的技术基础研究[D].北京:清华大学,2013.
[10] 赵海宝,郦建国,何毓忠,等.低低温电除尘关键技术研究与应用[J].中国电力,2014,47(10):117-121,147.ZHAO Haibao,LI Jianguo,HE Yuzhong,et al.Research and application on low-low temperature electrostatic precipitator technology[J].Electric Power,2014,47(10):117-121,147.
[11] KATO M,TANAKA T,NISHIMURA Y,et al.Method and system for handling exhaust gas in a boiler:USA5282429[P].1994-02-01.
[12] YOKOYAMA T,ASAKURA K,MATSUDA H,et al.Mercury emissions from a coal-fired power plant in Japan[J].The Science of the Total Environment,2000,259(1/2/3):97-103.
[13] 赵继尧,唐修义,黄文辉.中国煤中微量元素的丰度[J].中国煤田地质,2002,14(增刊1):5-13,17.ZHAO Jiyao,TANG Xiuyi,HUANG Wenhui.Abundance of trace elements in coal of China[J].Coal Geology of China,2002,14(Sup1):5-13,17.
[14] XU Minghou,QIAO Yu,ZHENG Chuguang,et al.Modeling of homogeneous mercury speciation using detailed chemical kinetics[J].Combustion and Flame,2003,132(1/2):208-218.
[15] BUITRAGO P A.Gas-phase mercury oxidation:effects of bromine,chlorine and SO2 under air firing and oxy-fuel conditions,experimental and modeling study[D].Salt Lake City,USA:the University of Utah,2011.
[16] NORTON G A,YANG Hongqun,BROWN R C,et al.Heterogeneous oxidation of mercury in simulated post combustion conditions[J].Fuel,2003,82(2):107-116.
[17] 江贻满,段钰锋,杨祥花,等.ESP飞灰对燃煤锅炉烟气汞的吸附特性[J].东南大学学报(自然科学版),2007,37(3):436-440.JIANG Yiman,DUAN Yufeng,YANG Xianghua,et al.Adsorption characterization of coal fired flue gas mercury by ESP fly ashes[J].Journal of Southeast University (Natural Science Edition),2007,37(3):436-440.
[18] 刘含笑,姚宇平,郦建国,等.低低温条件下飞灰工况比电阻特性[J].洁净煤技术,2017,23(5):125-128.LIU Hanxiao,YAO Yuping,LI Jianguo,et al.Resistivity characteristics of fly ash under low-low temperature[J].Clean Coal Technology,2017,23(5):125-128.