某1000 MW超超临界燃煤机组尾部烟道硫酸铵盐沉积分析
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摘要
超低排放技术可有效降低燃煤机组污染物排放,改善空气质量。为探究超低排放机组尾部烟道积灰、结垢问题的产生机理,以某1 000 MW超低排放机组引风机与二级低温省煤器的结垢灰样为研究对象,采用元素分析仪、X射线荧光光谱仪、X射线衍射仪和扫描电镜对灰样进行检测,详细分析并讨论了积灰样品中结晶矿物相的形成以及不同位置发生积灰的主要原因。结果表明:引风机与二级低温省煤器颗粒沉积位置的灰样主要由(NH_4)Al(SO_4)_2·12H_2O、(NH_4)_3H(SO_4)_2、CaSO_4、SiO_2等结晶矿物质构成;其中,(NH_4)Al(SO_4)_2覆盖于灰颗粒表面是造成引风机及二级低温省煤器严重结垢积灰的直接原因,而SCR脱硝系统较高浓度氨持续逃逸则是其根本原因。建议应根据煤种硫分、氨逃逸量、灰浓度等合理分配一、二级低温省煤器处的烟气温降,避免静电除尘器脱离低低温状态运行,防止二级低温省煤器处烟温降低幅度过大导致硫酸酸雾快速冷凝。
The ultra-low emission technology can effectively reduce pollutant emissions from coal-fired units and improve the air quality. In order to explore the mechanism of fouling in the tail flue of ultra-low emission units, this paper takes the fouling ash on the induced draft fan and the second stage low temperature economizer(LTE) of a 1000-MW unit with ultra-low emission as the research object. The ash samples are examined by using the elemental analyzer, the X-ray fluorescence spectrometer, the X-ray diffraction and the scanning electron microscopy. Then, the major factors contributing to the formation of the crystalline mineral phase of the ash and the ash deposition occurrence at different locations are analyzed and discussed in details. The results show that the ashes on the blades of the induced draft fan and the second stage LTE are mainly comprised of(NH_4)Al(SO_4)_2·12H_2O,(NH_4)_3H(SO_4)_2,CaSO_4 and SiO_2. Among them(NH_4)_3 H(SO_4)_2 covering on the surface of the ash particles is the immediate cause of the severe ash deposition on the induced draft fan and LTE, while, the root cause is determined as the ammonia escape from the SCR.At last, this paper suggests that the temperature drop of the flue gas at the first and second stage economizers should be properly distributed considering the sulfur contents of the coal, the ammonia emissions and the ash concentrations, so as to prevent the ESP being operated out of low-low temperature conditions and avoid drastic flue gas temperature drop at the second stage LTE which may cause the rapid condensing of sulfuric acid mist.
The ultra-low emission technology can effectively reduce pollutant emissions from coal-fired units and improve the air quality. In order to explore the mechanism of fouling in the tail flue of ultra-low emission units, this paper takes the fouling ash on the induced draft fan and the second stage low temperature economizer(LTE) of a 1000-MW unit with ultra-low emission as the research object. The ash samples are examined by using the elemental analyzer, the X-ray fluorescence spectrometer, the X-ray diffraction and the scanning electron microscopy. Then, the major factors contributing to the formation of the crystalline mineral phase of the ash and the ash deposition occurrence at different locations are analyzed and discussed in details. The results show that the ashes on the blades of the induced draft fan and the second stage LTE are mainly comprised of(NH_4)Al(SO_4)_2·12H_2O,(NH_4)_3H(SO_4)_2,CaSO_4 and SiO_2. Among them(NH_4)_3 H(SO_4)_2 covering on the surface of the ash particles is the immediate cause of the severe ash deposition on the induced draft fan and LTE, while, the root cause is determined as the ammonia escape from the SCR.At last, this paper suggests that the temperature drop of the flue gas at the first and second stage economizers should be properly distributed considering the sulfur contents of the coal, the ammonia emissions and the ash concentrations, so as to prevent the ESP being operated out of low-low temperature conditions and avoid drastic flue gas temperature drop at the second stage LTE which may cause the rapid condensing of sulfuric acid mist.
引文
[1]谭厚章,熊英莹,王毅斌,等.湿式相变凝聚器协同多污染物脱除研究[J].中国电力,2017,50(2):128-134.TAN Houzhang,XIONG Yingying,WANG Yibin,et al.Study on synergistic removal of multi-pollutants by WPTA[J].Electric Power,2017,50(2):128-134.
[2]王娴娜,朱林,姜艳靓,等.燃煤电厂烟尘超低排放技术措施研究[J].电力科技与环保,2015(4):47-49.WANG Xianna,ZHU Lin,JIANG Yanliang,et al.Measures of ultralow emission technology of coal-fired power plant smoke[J].Electric Power Environmental Protection,2015(4):47-49.
[3]朱法华,李辉,王强.高频电源在我国电除尘器上的应用及节能减排潜力分析[J].环境工程技术学报,2011,1(1):26-32.ZHU Fahua,LI Hui,WANG Qiang.Application of high frequency power supply for ESP in the power industry of China and its potential for energy saving and emissions reducing[J].Journal of Environmental Engineering Technology,2011,1(1):26-32.
[4]闫克平,李树然,冯卫强,等.高电压环境工程应用研究关键技术问题分析及展望[J].高电压技术,2015,41(8):2528-2544.YAN Keping,LI Shuran,FENG Weiqiang,et al.Analysis and prospect on key technology of high-voltage discharge for environmental engineering study and application[J].High Voltage Engineering,2015,41(8):2528-2544.
[5]王建峰,李艳,张杨,等.300 MW燃煤机组低低温除尘与电袋复合除尘技术经济性分析[J].中国电力,2015,48(8):17-19.WANG Jianfeng,LI Yan,ZHANG Yang,et al.A case of economic comparison between low-low temperature dust removal technique and electric-baghouse combined dust removal technique in the 300-MW unit improvement[J].Electric Power,2015,48(8):17-19.
[6]张东辉,庄烨,朱润儒,等.燃煤烟气污染物超低排放技术及经济分析[J].电力建设,2015,36(5):125-130.ZHANG Donghui,ZHUANG Ye,ZHU Runru,et al.Ultra-low air pollutant control technologies for coal-fired flue gas and its economic analysis[J].Electric Power Construction,2015,36(5):125-130.
[7]朱法华.燃煤电厂烟气污染物超低排放技术路线的选择[J].中国电力,2017,50(3):11-16.ZHU Fahua.Methodologies on choosing appropriate technical route for ultra low emission of flue gas pollutants from coal-fired power plants[J].Electric Power,2017,50(3):11-16.
[8]夏力伟,张学锁,梁会有,等.脱硫协同除尘技术在大型火电机组中的应用研究[J].中国高新技术企业,2016,23(12):83-85.XIA Liwei,ZHANG Xuesuo,LIANG Huiyou,et al.Research on the application of desulfurization co-precipitation technology in the large thermal power plant[J].China High Technology Enterprises,2016,23(12):83-85.
[9]李元,杨志忠.湿法烟气脱硫关键影响因素及新型单塔双循环技术[J].环境工程,2016,35(1):69-73.LI Yuan,YANG Zhizhong.Influence of key factors on lime-gypsum wet flue gas desulfurization and two circulations per tower technology[J].Environmental Engineering,2016,35(1):69-73.
[10]王文选,肖志均,夏怀祥.火电厂脱硝技术综述[J].电力设备,2006,7(8):1-5.WANG Wenxuan,XIAO Zhijun,XIA Huaixiang.A summary of denitration technology of thermal power plants[J].Electrical Equipment,2006,7(8):1-5.
[11]马双忱,郭蒙,宋卉卉,等.选择性催化还原工艺中硫酸氢铵形成机理及影响因素[J].热力发电,2014,43(2):75-78.MA Shuangchen,GUO Meng,SONG Huihui,et al.Formation mechanism and influencing factors of ammonium bisulfate during the selective catalytic reduction process[J].Thermal Power Generation,2014,43(2):75-78.
[12]崔占忠,龙辉,龙正伟,等.低低温高效烟气处理技术特点及其在中国的应用前景[J].动力工程学报,2012,32(2):152-158.CUI Zhanzhong,LONG Hui,LONG Zhengwei,et al.Technical features of lower temperature high efficiency flue gas treatment system and its application prospects in China[J].Power Engineering,2012,32(2):152-158.
[13]胡斌,刘勇,任飞,等.低低温电除尘协同脱除细颗粒与SO3实验研究[J].中国电机工程学报,2016,36(16):4319-4325.HU Bin,LIU Yong,REN Fei,et al.Experimental study on simultaneous control of fine particle and SO3 by low-low temperature electrostatic precipitator[J].Proceedings of the CSEE,2016,36(16):4319-4325.
[14]王乐乐,孔凡海,何金亮,等.超低排放形势下SCR脱硝系统运行存在问题与对策[J].热力发电,2016,45(12):19-24.WANG Lele,KONG Fanhai,HE Jinliang,et al.Difficulties and countermeasures of SCR denitration system operation in ultra low emission situation[J].Thermal Power Generation,2016,45(12):19-24.
[15]王毅斌,谭厚章,萧嘉繁,等.超低排放燃煤电厂引风机叶片硫酸盐沉积分析[J].热力发电,2016,45(12):9-13.WANG Yibin,TAN Houzhang,XIAO Jiafan,et al.Analysis of sulfates deposition on induced draft fan blade in a coal-fired power plant with ultra-low emission[J].Thermal Power Generation,2016,45(12):9-13.
[16]丁虹,何雁飞,陈增宏.省煤器积灰原因分析及改进措施[J].工业锅炉,2012(1):30-34.DING Hong,HE Yanfei,CHEN Zenghong.Analysis of economizer ash deposite and its countermeasures[J].Industrial Boiler,2012(1):30-34.
[17]冯俊凯.锅炉机组热力计算标准方法[M].北京:机械工业出版社,1976.
[18]王崇臣,王鹏.十二水硫酸铝铵的制备与表征[J].实验室科学,2013,16(6):4-6.WANG Chongchen,WANG Peng.Preparation and characterization of aluminum ammonium sulfate dodecahydrate[J].Laboratory Science,2013,16(6):4-6.
[19]刘萍,苏志宏,余钱伟.高纯硫酸铝铵生产工艺的改进[J].河南化工,2002(7):24-25.LIU Ping,SU Zhihong,YU Qianwei.Improvement of production process of high-purity aluminum ammonium sulfate[J].Henan Chemical Industry,2002(7):24-25.
[20]吴限博,沈俊,游贤贵,等.氯化铵与硫酸反应制备硫酸铵盐和氯化氢[J].无机盐工业,2008,40(1):14-16.WU Xianbo,SHEN Jun,YOU Xiangui,et al.Study on reaction between ammonium chloride and sulfuric acid to produce ammonium sulfates and hydrogen chloride[J].Inorganic Chemicals Industry,2008,40(1):14-16.
[21]马双忱,金鑫,孙云雪,等.SCR烟气脱硝过程硫酸氢铵的生成机理与控制[J].热力发电,2010,39(8):12-17.MA Shuangchen,JIN Xin,SUN Yunxue,et al.The formation mechanism of ammonium bisulfate in SCR flue gas denitrification process and control thereof[J].Thermal Power Generation,2010,39(8):12-17.
[2]王娴娜,朱林,姜艳靓,等.燃煤电厂烟尘超低排放技术措施研究[J].电力科技与环保,2015(4):47-49.WANG Xianna,ZHU Lin,JIANG Yanliang,et al.Measures of ultralow emission technology of coal-fired power plant smoke[J].Electric Power Environmental Protection,2015(4):47-49.
[3]朱法华,李辉,王强.高频电源在我国电除尘器上的应用及节能减排潜力分析[J].环境工程技术学报,2011,1(1):26-32.ZHU Fahua,LI Hui,WANG Qiang.Application of high frequency power supply for ESP in the power industry of China and its potential for energy saving and emissions reducing[J].Journal of Environmental Engineering Technology,2011,1(1):26-32.
[4]闫克平,李树然,冯卫强,等.高电压环境工程应用研究关键技术问题分析及展望[J].高电压技术,2015,41(8):2528-2544.YAN Keping,LI Shuran,FENG Weiqiang,et al.Analysis and prospect on key technology of high-voltage discharge for environmental engineering study and application[J].High Voltage Engineering,2015,41(8):2528-2544.
[5]王建峰,李艳,张杨,等.300 MW燃煤机组低低温除尘与电袋复合除尘技术经济性分析[J].中国电力,2015,48(8):17-19.WANG Jianfeng,LI Yan,ZHANG Yang,et al.A case of economic comparison between low-low temperature dust removal technique and electric-baghouse combined dust removal technique in the 300-MW unit improvement[J].Electric Power,2015,48(8):17-19.
[6]张东辉,庄烨,朱润儒,等.燃煤烟气污染物超低排放技术及经济分析[J].电力建设,2015,36(5):125-130.ZHANG Donghui,ZHUANG Ye,ZHU Runru,et al.Ultra-low air pollutant control technologies for coal-fired flue gas and its economic analysis[J].Electric Power Construction,2015,36(5):125-130.
[7]朱法华.燃煤电厂烟气污染物超低排放技术路线的选择[J].中国电力,2017,50(3):11-16.ZHU Fahua.Methodologies on choosing appropriate technical route for ultra low emission of flue gas pollutants from coal-fired power plants[J].Electric Power,2017,50(3):11-16.
[8]夏力伟,张学锁,梁会有,等.脱硫协同除尘技术在大型火电机组中的应用研究[J].中国高新技术企业,2016,23(12):83-85.XIA Liwei,ZHANG Xuesuo,LIANG Huiyou,et al.Research on the application of desulfurization co-precipitation technology in the large thermal power plant[J].China High Technology Enterprises,2016,23(12):83-85.
[9]李元,杨志忠.湿法烟气脱硫关键影响因素及新型单塔双循环技术[J].环境工程,2016,35(1):69-73.LI Yuan,YANG Zhizhong.Influence of key factors on lime-gypsum wet flue gas desulfurization and two circulations per tower technology[J].Environmental Engineering,2016,35(1):69-73.
[10]王文选,肖志均,夏怀祥.火电厂脱硝技术综述[J].电力设备,2006,7(8):1-5.WANG Wenxuan,XIAO Zhijun,XIA Huaixiang.A summary of denitration technology of thermal power plants[J].Electrical Equipment,2006,7(8):1-5.
[11]马双忱,郭蒙,宋卉卉,等.选择性催化还原工艺中硫酸氢铵形成机理及影响因素[J].热力发电,2014,43(2):75-78.MA Shuangchen,GUO Meng,SONG Huihui,et al.Formation mechanism and influencing factors of ammonium bisulfate during the selective catalytic reduction process[J].Thermal Power Generation,2014,43(2):75-78.
[12]崔占忠,龙辉,龙正伟,等.低低温高效烟气处理技术特点及其在中国的应用前景[J].动力工程学报,2012,32(2):152-158.CUI Zhanzhong,LONG Hui,LONG Zhengwei,et al.Technical features of lower temperature high efficiency flue gas treatment system and its application prospects in China[J].Power Engineering,2012,32(2):152-158.
[13]胡斌,刘勇,任飞,等.低低温电除尘协同脱除细颗粒与SO3实验研究[J].中国电机工程学报,2016,36(16):4319-4325.HU Bin,LIU Yong,REN Fei,et al.Experimental study on simultaneous control of fine particle and SO3 by low-low temperature electrostatic precipitator[J].Proceedings of the CSEE,2016,36(16):4319-4325.
[14]王乐乐,孔凡海,何金亮,等.超低排放形势下SCR脱硝系统运行存在问题与对策[J].热力发电,2016,45(12):19-24.WANG Lele,KONG Fanhai,HE Jinliang,et al.Difficulties and countermeasures of SCR denitration system operation in ultra low emission situation[J].Thermal Power Generation,2016,45(12):19-24.
[15]王毅斌,谭厚章,萧嘉繁,等.超低排放燃煤电厂引风机叶片硫酸盐沉积分析[J].热力发电,2016,45(12):9-13.WANG Yibin,TAN Houzhang,XIAO Jiafan,et al.Analysis of sulfates deposition on induced draft fan blade in a coal-fired power plant with ultra-low emission[J].Thermal Power Generation,2016,45(12):9-13.
[16]丁虹,何雁飞,陈增宏.省煤器积灰原因分析及改进措施[J].工业锅炉,2012(1):30-34.DING Hong,HE Yanfei,CHEN Zenghong.Analysis of economizer ash deposite and its countermeasures[J].Industrial Boiler,2012(1):30-34.
[17]冯俊凯.锅炉机组热力计算标准方法[M].北京:机械工业出版社,1976.
[18]王崇臣,王鹏.十二水硫酸铝铵的制备与表征[J].实验室科学,2013,16(6):4-6.WANG Chongchen,WANG Peng.Preparation and characterization of aluminum ammonium sulfate dodecahydrate[J].Laboratory Science,2013,16(6):4-6.
[19]刘萍,苏志宏,余钱伟.高纯硫酸铝铵生产工艺的改进[J].河南化工,2002(7):24-25.LIU Ping,SU Zhihong,YU Qianwei.Improvement of production process of high-purity aluminum ammonium sulfate[J].Henan Chemical Industry,2002(7):24-25.
[20]吴限博,沈俊,游贤贵,等.氯化铵与硫酸反应制备硫酸铵盐和氯化氢[J].无机盐工业,2008,40(1):14-16.WU Xianbo,SHEN Jun,YOU Xiangui,et al.Study on reaction between ammonium chloride and sulfuric acid to produce ammonium sulfates and hydrogen chloride[J].Inorganic Chemicals Industry,2008,40(1):14-16.
[21]马双忱,金鑫,孙云雪,等.SCR烟气脱硝过程硫酸氢铵的生成机理与控制[J].热力发电,2010,39(8):12-17.MA Shuangchen,JIN Xin,SUN Yunxue,et al.The formation mechanism of ammonium bisulfate in SCR flue gas denitrification process and control thereof[J].Thermal Power Generation,2010,39(8):12-17.