SNCR/烟气再循环协同脱硝技术研究
|
摘要
短期内煤炭作为我国主要能源的现状不会改变。由于煤燃烧会释放大量NO_x,造成严重的环境污染,因此煤炭燃烧过程中的NO_x控制至关重要。链条锅炉作为我国工业应用最为广泛的燃煤锅炉之一,是降低NO_x排放的重点对象,尤其在新实施的GB 13271—2014《锅炉大气污染物排放标准》中规定重点地区锅炉NO_x排放值不得高于200 mg/m~3后,链条炉低氮燃烧和NO_x脱除技术受到广泛关注。为降低链条锅炉NO_x排放,满足国家环保要求的同时,降低企业运行维护成本,提高企业经济效益,以西安高新区某供热站4×75 t/h链条锅炉为研究对象,进行烟气再循环与SNCR耦合低氮燃烧NO_x脱除技术改造研究。研究了SNCR与烟气再循环耦合低氮燃烧系统参数,如烟气再循环率,再循环烟气一、二次风室送入比例,氨氮摩尔比,锅炉负荷变化等脱硝系统参数对NO_x脱除效率及链条炉燃烧特性的影响,确定了烟气再循环与SNCR技术耦合脱硝的最佳运行参数,结果表明:SNCR耦合烟气再循环低氮燃烧技术能有效降低链条锅炉NO_x排放。烟气再循环率为16%～18%,再循环烟气一次风室送入比例为82%,氨氮摩尔比为0.78时,SNCR耦合烟气在循环脱硝系统可达最佳脱硝效率。此时SNCR耦合烟气再循环联合脱硝效率可达到56%,SNCR单独运行脱硝效率可达40%,NO_x实际排放可从250 mg/m~3降至110 mg/m~3,远高于国家NO_x排放标准。
In the short term,the status quo of coal as the main energy in China will not change.Because coal combustion will release a lot of NO_xand cause serious environmental pollution,so the control of NO_xin coal combustion process is very important.Chain grate furnace as one of the most widely used coal-fired boilers in China must be paid more attention to the reduction of NO_xemission.Especially with the implementation of Boiler Air Pollutant Emission Standard(GB 13271—2014),the NO_xemission value of grate furnace in key areas should not be higher than 200 mg/m~3,the technology of low-nitrogen combustion and NO_xremoval in chain grate furnace has attracted wide attention.In order to reduce the NO_xemission of chain grate furnace,meet the requirements of national environmental protection,reduce the cost of operation and maintenance of enterprises and improve the economic benefits of enterprises,the technical improvement study of flue gas recirculation and SNCR denitrification system was performed in a 4×75 t/h chain grate furnace of a heating station at Gaoxin District in Xi'an to reduce the NO_xemission.The influence of the parameters of SNCR and flue gas recirculation coupled low nitrogen combustion system,such as flue gas recirculation ratio,the feed ratio of recirculation flue gas in primary and second air chamber,the ammonia nitrogen molar ratio and the change of boiler load on NO_xremoval efficiency and combustion characteristics were researched.The optimum operating parameters of flue gas recirculation coupled with SNCR technology were determined.The results show that the SNCR coupled flue gas recirculation low nitrogen combustion technology can effectively reduce the NO_xemission of chain grate furnace.When the flue gas recirculation rate is 16%-18%,the feed ratio of recirculation flue gas in primary air chamber is 82%,and the molar ratio of ammonia nitrogen is 0.78,the SNCR coupled flue gas can achieve the best denitrification efficiency in the circulating system.At this point,the denitration efficiency of SNCR coupling flue gas recycling is up to 56%and the denitrification efficiency of SNCR single operation is 40%and the actual NO_xemission is reduced from 250 mg/m~3to 110 mg/m~3,which is much higher than the national emission standard of NO_x.
In the short term,the status quo of coal as the main energy in China will not change.Because coal combustion will release a lot of NO_xand cause serious environmental pollution,so the control of NO_xin coal combustion process is very important.Chain grate furnace as one of the most widely used coal-fired boilers in China must be paid more attention to the reduction of NO_xemission.Especially with the implementation of Boiler Air Pollutant Emission Standard(GB 13271—2014),the NO_xemission value of grate furnace in key areas should not be higher than 200 mg/m~3,the technology of low-nitrogen combustion and NO_xremoval in chain grate furnace has attracted wide attention.In order to reduce the NO_xemission of chain grate furnace,meet the requirements of national environmental protection,reduce the cost of operation and maintenance of enterprises and improve the economic benefits of enterprises,the technical improvement study of flue gas recirculation and SNCR denitrification system was performed in a 4×75 t/h chain grate furnace of a heating station at Gaoxin District in Xi'an to reduce the NO_xemission.The influence of the parameters of SNCR and flue gas recirculation coupled low nitrogen combustion system,such as flue gas recirculation ratio,the feed ratio of recirculation flue gas in primary and second air chamber,the ammonia nitrogen molar ratio and the change of boiler load on NO_xremoval efficiency and combustion characteristics were researched.The optimum operating parameters of flue gas recirculation coupled with SNCR technology were determined.The results show that the SNCR coupled flue gas recirculation low nitrogen combustion technology can effectively reduce the NO_xemission of chain grate furnace.When the flue gas recirculation rate is 16%-18%,the feed ratio of recirculation flue gas in primary air chamber is 82%,and the molar ratio of ammonia nitrogen is 0.78,the SNCR coupled flue gas can achieve the best denitrification efficiency in the circulating system.At this point,the denitration efficiency of SNCR coupling flue gas recycling is up to 56%and the denitrification efficiency of SNCR single operation is 40%and the actual NO_xemission is reduced from 250 mg/m~3to 110 mg/m~3,which is much higher than the national emission standard of NO_x.
引文
[1]王少波.660 MW火电机组降低NOx排放试验研究[D].北京:华北电力大学,2013.
[2]于林平,贾建军.城市光化学烟雾的形成机理及防治[J].山东科技大学学报(自然科学版),2001,20(4):111-114.YU Linping,JIA Jianjun. The mechanism of photochemical smog formation in the city and its prevention and control[J]. Journal of Shandong University of Science and Technology(Natural Science),2001,20(4):111-114.
[3]聂虎,余春江,柏继松,等.生物质燃烧中硫氧化物和氮氧化物生成机理研究[J].热力发电,2010,39(9):21-26,34.NIE Hu,YU Chunjiang,BAI Jisong,et al.Study on formation mechanism of sulphide and nitrogen oxides in combustion of biomass[J].Thermal Power Generation,2010,39(9):21-26,34.
[4]马强.烟气中多种污染物超低排放的活性分子氧化及一体化脱除机理研究[D].杭州:浙江大学,2016.
[5]徐天平,王永忠.燃煤工业锅炉污染物协同治理与超低排放技术研究[J].环境工程,2017,35(9):71-73.XU Tianping,WANG Yongzhong.Study on synergy treatment&ultra-low emission technology for pollutants from coal fired industrial boilers[J].Environmental Engineering,2017,35(9):71-73.
[6] HOUSHFAR E,KHALIL R A T.Enhanced NOxreduction by combined staged air and flue gas recirculation in biomass grate combustion[J].Energy&Fuels,2012,26:3003-3011.
[7]胡满银,韩静,刘忠.烟气再循环及分段送风对链条炉NOx生成的数值模拟[J].洁净煤技术,2009,16(3):70-73.HU Manyin,HAN Jing,LIU Zhong.Numerical simulation for influence of flue gas recycle and zoned air on NOxformation in chain boiler[J].Clean Coal Technology,2009,16(3):70-73.
[8]胥波,张彦文,蔡宁生.链条炉SNCR脱除NOx数值模拟研究[J].热力发电,2009,38(3):18-25.XU Bo,ZHANG Yanwen,CAI Ningsheng. Simulation study on SNCR for NOxremoval from chain-grate furnace[J] Thermal Power Generation,2009,38(3):18-25.
[9]李维成,李振山,蔡宁生.35 t/h链条炉氨水SNCR数值模拟[C]//中国工程热物理年会(燃烧学).广州:[s.n.],2010.
[10]孙献斌,时正海,金森旺.循环流化床锅炉超低排放技术研究[J].中国电力,2014,47(1):142-145.SUN Xianbin,SHI Zhenghai,JIN Senwang.Research on ultra-low emission technology for CFB boilers[J].Electric Power,2014,47(1):142-145.
[11]贾力,殷龙.烟气再循环实现低NOx排放的实验研究[J].工业加热,2003,19(6):47-49.JIA Li,YIN Long.The experimental research on realizing low NOx emission with recycle of flue gas[J].Industrial Heating,2003,19(6):47-49.
[12]陈杏.低氮燃烧+选择性非催化还原烟气脱硝技术(SNCR)在循环流化床锅炉脱硝工程上的应用[J].能源环境保护,2013,27(4):33-35.CHEN Xing. Engineering application of low NOx combustion+SNCR technology for flue gas De NOxof CFB boilers[J].Energy and Environmental Protection,2013,27(4):33-35.
[13]凌忠钱,况敏,谭立武.具有两级烟气再循环的低氮燃烧链条炉:CN104791772B[P].2017-02-01.
[14]王方群,杜云贵,刘艺,等.国内燃煤电厂烟气脱硝发展现状及建议[J].中国环保产业,2007(1):18-22.WANG Fangqun,DU Yungui,LIU Yi,et al. Development status and recommendations on flue gas denitration in coal-fired power plant in China[J].China Environmental Protection Industry,2007(1):18-22.
[15]顾卫荣,周明吉,马薇.燃煤烟气脱硝技术的研究进展[J].化工进展,2012,31(9):2084-2092.GU Weirong,ZHOU Mingji,MA Wei.Technology status and analysis on coal-fired flue gas denitrification[J]. Chemical Industry and Engineering Progress,2012,31(9):2084-2092.
[16]胡浩毅.以尿素为还原剂的SNCR脱硝技术在电厂的应用[J].热力发电,2009,38(3):22-24,28.
[17]巩志强,周托,刘志成,等.循环流化床燃用半焦SNCR脱硝特性试验研究[J].煤炭学报,2015,40(S2):517-523.GONG Zhiqiang,ZHOU Tuo,LIU Zhicheng,et al. Experimental study on NOxremoval characteristics of SNCR in a char-fired circulating fluidized bed[J].Journal of China Coal Society,2015,40(S2):517-523.
[18]宋少鹏,卓建坤,李娜,等.燃料分级与烟气再循环对天然气低氮燃烧特性影响机理[J].中国电机工程学报,2016,36(24):6849-6858.SONG Shaopeng,ZHUO Jiankun,LI Na,et al. Low NOxcombustion mechanism of anatural gas burner with fuel-staged and flue gas recirculation[J]. Proceedings of the CSEE,2016,36(24):6849-6858.
[19]郭欣维,张健,张忠孝,等.新型烟气再循环技术对链条锅炉NOx脱除的试验研究[J].能源工程,2017(4):48-52.GUO Xinwei,ZHANG Jian,ZHANG Zhongxiao,et al. Test study of new flue gas re-circulation techniques working on NOxremoval in chain-stoked boiler[J].Energy Engineering,2017(4):48-52.
[20]陈国伟,张棋霞,万睿.反应温度和氨氮摩尔比对SNCR脱硝效果的影响[J].化学工程与装备,2016(6):265-266.
[2]于林平,贾建军.城市光化学烟雾的形成机理及防治[J].山东科技大学学报(自然科学版),2001,20(4):111-114.YU Linping,JIA Jianjun. The mechanism of photochemical smog formation in the city and its prevention and control[J]. Journal of Shandong University of Science and Technology(Natural Science),2001,20(4):111-114.
[3]聂虎,余春江,柏继松,等.生物质燃烧中硫氧化物和氮氧化物生成机理研究[J].热力发电,2010,39(9):21-26,34.NIE Hu,YU Chunjiang,BAI Jisong,et al.Study on formation mechanism of sulphide and nitrogen oxides in combustion of biomass[J].Thermal Power Generation,2010,39(9):21-26,34.
[4]马强.烟气中多种污染物超低排放的活性分子氧化及一体化脱除机理研究[D].杭州:浙江大学,2016.
[5]徐天平,王永忠.燃煤工业锅炉污染物协同治理与超低排放技术研究[J].环境工程,2017,35(9):71-73.XU Tianping,WANG Yongzhong.Study on synergy treatment&ultra-low emission technology for pollutants from coal fired industrial boilers[J].Environmental Engineering,2017,35(9):71-73.
[6] HOUSHFAR E,KHALIL R A T.Enhanced NOxreduction by combined staged air and flue gas recirculation in biomass grate combustion[J].Energy&Fuels,2012,26:3003-3011.
[7]胡满银,韩静,刘忠.烟气再循环及分段送风对链条炉NOx生成的数值模拟[J].洁净煤技术,2009,16(3):70-73.HU Manyin,HAN Jing,LIU Zhong.Numerical simulation for influence of flue gas recycle and zoned air on NOxformation in chain boiler[J].Clean Coal Technology,2009,16(3):70-73.
[8]胥波,张彦文,蔡宁生.链条炉SNCR脱除NOx数值模拟研究[J].热力发电,2009,38(3):18-25.XU Bo,ZHANG Yanwen,CAI Ningsheng. Simulation study on SNCR for NOxremoval from chain-grate furnace[J] Thermal Power Generation,2009,38(3):18-25.
[9]李维成,李振山,蔡宁生.35 t/h链条炉氨水SNCR数值模拟[C]//中国工程热物理年会(燃烧学).广州:[s.n.],2010.
[10]孙献斌,时正海,金森旺.循环流化床锅炉超低排放技术研究[J].中国电力,2014,47(1):142-145.SUN Xianbin,SHI Zhenghai,JIN Senwang.Research on ultra-low emission technology for CFB boilers[J].Electric Power,2014,47(1):142-145.
[11]贾力,殷龙.烟气再循环实现低NOx排放的实验研究[J].工业加热,2003,19(6):47-49.JIA Li,YIN Long.The experimental research on realizing low NOx emission with recycle of flue gas[J].Industrial Heating,2003,19(6):47-49.
[12]陈杏.低氮燃烧+选择性非催化还原烟气脱硝技术(SNCR)在循环流化床锅炉脱硝工程上的应用[J].能源环境保护,2013,27(4):33-35.CHEN Xing. Engineering application of low NOx combustion+SNCR technology for flue gas De NOxof CFB boilers[J].Energy and Environmental Protection,2013,27(4):33-35.
[13]凌忠钱,况敏,谭立武.具有两级烟气再循环的低氮燃烧链条炉:CN104791772B[P].2017-02-01.
[14]王方群,杜云贵,刘艺,等.国内燃煤电厂烟气脱硝发展现状及建议[J].中国环保产业,2007(1):18-22.WANG Fangqun,DU Yungui,LIU Yi,et al. Development status and recommendations on flue gas denitration in coal-fired power plant in China[J].China Environmental Protection Industry,2007(1):18-22.
[15]顾卫荣,周明吉,马薇.燃煤烟气脱硝技术的研究进展[J].化工进展,2012,31(9):2084-2092.GU Weirong,ZHOU Mingji,MA Wei.Technology status and analysis on coal-fired flue gas denitrification[J]. Chemical Industry and Engineering Progress,2012,31(9):2084-2092.
[16]胡浩毅.以尿素为还原剂的SNCR脱硝技术在电厂的应用[J].热力发电,2009,38(3):22-24,28.
[17]巩志强,周托,刘志成,等.循环流化床燃用半焦SNCR脱硝特性试验研究[J].煤炭学报,2015,40(S2):517-523.GONG Zhiqiang,ZHOU Tuo,LIU Zhicheng,et al. Experimental study on NOxremoval characteristics of SNCR in a char-fired circulating fluidized bed[J].Journal of China Coal Society,2015,40(S2):517-523.
[18]宋少鹏,卓建坤,李娜,等.燃料分级与烟气再循环对天然气低氮燃烧特性影响机理[J].中国电机工程学报,2016,36(24):6849-6858.SONG Shaopeng,ZHUO Jiankun,LI Na,et al. Low NOxcombustion mechanism of anatural gas burner with fuel-staged and flue gas recirculation[J]. Proceedings of the CSEE,2016,36(24):6849-6858.
[19]郭欣维,张健,张忠孝,等.新型烟气再循环技术对链条锅炉NOx脱除的试验研究[J].能源工程,2017(4):48-52.GUO Xinwei,ZHANG Jian,ZHANG Zhongxiao,et al. Test study of new flue gas re-circulation techniques working on NOxremoval in chain-stoked boiler[J].Energy Engineering,2017(4):48-52.
[20]陈国伟,张棋霞,万睿.反应温度和氨氮摩尔比对SNCR脱硝效果的影响[J].化学工程与装备,2016(6):265-266.