水汽相变促进湿法脱硫净烟气中细颗粒物脱除的研究?
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摘要
结合脱硫净烟气特点,提出分别通过脱硫净烟气中加装氟塑料换热器降温、添加蒸汽、添加冷空气3种措施建立细颗粒物凝结长大所需的过饱和水汽环境,进而增强后续高效除雾器的拦截脱除效果。数值分析了3种措施的可行性,并利用燃煤热态试验平台,对比考察了不同方式促进细颗粒物脱除的效果。结果表明:典型工况下,加装氟塑料换热器、添加蒸汽、添加冷空气三种措施均可使脱硫净烟气中细颗粒物排放浓度降低35%以上;其中,加装氟塑料换热器降温措施对脱硫净烟气原始温度变化的适应性较强,细颗粒物脱除效率基本不随脱硫净烟气原始温度的变化而改变;添加蒸汽方式不适于脱硫净烟气温度较高的场合,且耗能较大;添加冷空气方式在脱硫净烟气温度较高(≥55℃)时效果显著,但所需冷空气的温度较低,存在来源困难等问题。
Supersaturated vapor conditions for fine particle enlargement were established based on desulfurized flue gas characteristics after wet desulfurization in a condensational growth chamber(CGC) via three different methods(with heat exchanger, steam addition or cold air addition). Fine particles could be activated in supersaturated vapor and became condensation nucleus. The methods were evaluated numerically and particle removal performance was discussed using simulated coal-fired thermal system. The results indicate that the emission of fine particles can be reduced by 35% when using one of the methods. The heat exchanger method is suitable for desulfurized flue gas with different temperatures, and its removal efficiency keeps constant when the temperature of desulfurized flue gas changes. The steam addition method is not suitable for desulfurized flue gas of higher temperatures with high energy consumption, while the cold air addition method is efficient for desulfurized flue gas of higher temperatures(≥ 55 ℃), while it needs much lower cold air temperature which is difficult to obtain.
Supersaturated vapor conditions for fine particle enlargement were established based on desulfurized flue gas characteristics after wet desulfurization in a condensational growth chamber(CGC) via three different methods(with heat exchanger, steam addition or cold air addition). Fine particles could be activated in supersaturated vapor and became condensation nucleus. The methods were evaluated numerically and particle removal performance was discussed using simulated coal-fired thermal system. The results indicate that the emission of fine particles can be reduced by 35% when using one of the methods. The heat exchanger method is suitable for desulfurized flue gas with different temperatures, and its removal efficiency keeps constant when the temperature of desulfurized flue gas changes. The steam addition method is not suitable for desulfurized flue gas of higher temperatures with high energy consumption, while the cold air addition method is efficient for desulfurized flue gas of higher temperatures(≥ 55 ℃), while it needs much lower cold air temperature which is difficult to obtain.
引文
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[18]LEHTINEN K E J,HOKKINEN J,JOKINIEMI A A J K,et al.Studies on steam condensation and particle diffusiophoresis in a heat exchanger tube[J].Nuclear Engineering&Design,2002,213(1):67-77.
[19]陈冬林,杨陈好,吴康,等.烟气参数对细颗粒湍流聚并的影响[J].环境工程学报,2017,11(9):5084-5090.CHEN D L,YANG C H,WU K,et al.Influences of turbulent agglomeration of fine particles under flue gas parameters[J].Chinese Journal of Environmental Engineering,2017,11(9):5084-5090.
[2]PAN D,WU H,YANG L.Investigation of the relationship between droplets and fine particle emission during the limestone-gypsum WFGD process[J].Energy&Fuels,2017,31(6):6472-6477.
[3]李壮,王海涛,董鹤鸣,等.湿法脱硫对660 MW煤粉炉PM2.5排放影响的实验研究[J].节能技术,2015,33(5):398-402.LI Z,WANG H T,DONG H M,et al.Experimental study on the influence of wet desulfurization on PM2.5 emissions from a 660 MWpulverized coal boiler[J].Energy Conservation Technology,2015,33(5):398-402.
[4]LIU X,XU Y,ZENG X,et al.Field measurements on the emission and removal of PM2.5 from coal-fired power stations:1.Case study for a 1 000 MW ultrasupercritical utility boiler[J].Energy&Fuels,2016,30(8):6547-6654.
[5]BANDYOPADHYAY A,MANDAL P K.Investigation on multiple benefits of wet ESP for emission control in an Indian coal fired thermal power plant[J].Clean Technologies&Environmental Policy,2015,17(2):421-431.
[6]XU Y,LIU X,CUI J,et al.Field measurements on the emission and removal of PM2.5 from coal-fired power stations:4.PM removal performance of wet electrostatic precipitators[J].Energy&Fuels,2016,30(9):7465-7473.
[7]颜金培.蒸汽相变促进燃煤细颗粒物脱除的研究[D].南京:东南大学,2009.YAN J P.Study on fine particles removal from coal combustion improved by vapor condensational growth[D].Nanjing:Southeast University,2009.
[8]WU H,YANG L J,YAN J P,et al.Improving the removal of fine particles by heterogeneous condensation during WFGD processes[J].Fuel Processing Technology,2016,145:116-122.
[9]熊桂龙,辛成运,杨林军,等.蒸汽相变协同湿法烟气脱硫系统中烟气温湿度变化特性[J].中国电机工程学报,2011,31(8):18-24.XIONG G L,XIN C Y,YANG L J,et al.Temperature and humidity characteristics of flue gas from combined wet flue gas desulfurization system and heterogenous condensation[J].Proceedings of the CSEE,2011,31(8):18-24.
[10]FLETCHER N H.The physics of rainclouds[M].London:Cambridge University Press,1962.
[11]SMORODI V Y,HOPKE P K.Condensation activation and nucleation on heterogeneous aerosol nanoparticles[J].Journal of Physical Chemistry B,2004,108(26):9147-9157.
[12]COZZOLINO G.Water condensation for submicronic particles abatement[D].2013.
[13]WU H,PAN D,JIANG Y,et al.Improving the removal of fine particles from desulfurized flue gas by adding humid air[J].Fuel,2016,184:153-161.
[14]王圣,朱法华,王慧敏,等.基于实测的燃煤电厂细颗粒物排放特性分析与研究[J].环境科学学报,2011,31(3):630-635.WANG S,ZHU F H,WANG H M,et al.Fine particles emission characteristics from coal-fired power plants based on field tests[J].Acta Scientiae Circumstantiae,2011,31(3):630-635.
[15]陈浩,骆仲泱,江建平,等.电厂湿法烟气脱硫颗粒物排放特性的实验研究[J].动力工程学报,2017,37(11):925-930.CHEN H,LUO Z Y,JIANG J P,et al.Experimental study on emission characteristics of particulate matters from wet flue gas desulfurization system of a coal-fired power plants[J].Journal of Chinese Society of Power Engineering,2017,37(11):925-930.
[16]GRIGONYTE J,NUUTINEN I,KOPONEN T,et al.Evaluation of a heat exchanger designed for efficient fine particle precipitation in small-scale wood combustion[J].Energy&Fuels,2014,28(2014):6058-6065.
[17]GROHN A,SUONMAA V,AUVINEN A,et al.Reduction of fine particle emissions from wood combustion with optimized condensing heat exchangers[J].Environmental Science&Technology,2009,43(16):6269-6274.
[18]LEHTINEN K E J,HOKKINEN J,JOKINIEMI A A J K,et al.Studies on steam condensation and particle diffusiophoresis in a heat exchanger tube[J].Nuclear Engineering&Design,2002,213(1):67-77.
[19]陈冬林,杨陈好,吴康,等.烟气参数对细颗粒湍流聚并的影响[J].环境工程学报,2017,11(9):5084-5090.CHEN D L,YANG C H,WU K,et al.Influences of turbulent agglomeration of fine particles under flue gas parameters[J].Chinese Journal of Environmental Engineering,2017,11(9):5084-5090.