湿法脱硫喷淋除尘过程的数值模拟
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摘要
脱硫塔的协同除尘作用可进一步降低燃煤颗粒物的排放。建立了描述塔内气液固三相运动的数学模型与计算方法,对脱硫塔喷淋浆液的协同除尘过程进行数值模拟。结果表明:颗粒的脱除效率随颗粒粒径增加而升高;亚微米级颗粒主要靠热泳捕集,气液温差大的区域是其主要捕集区域;微米级颗粒主要靠惯性捕集,喷淋层附近单液滴捕集效率最高;入口附近液滴浓度高、气液温差大且原烟气的颗粒物浓度高,是各粒径颗粒被捕集的最主要区域。提高气液两相温差、气液相对速度、塔内液气比可优化脱硫塔的协同除尘性能。
The synergetic effect of wet flue gas desulfurization(WFGD) system can further reduce the emission of particulate matter from the coal-fired plants.Mathematical model and numerical method were established to describe the gas-liquid-solid three-phase movement in the tower, and the process of particle removal by spraying in WFGD system was simulated. The results show that the efficiency of particle removal increases with the increase of particle size. The major mechanism for capturing submicron particles is thermophoresis, and the region with large gas-liquid temperature difference is the main capturing area. Micron particles are captured mainly by inertial capture mechanism,and the capture efficiency of single droplet near the spray layers is the highest. Besides, the area near the flue gas inlet is with high concentration of droplets, large temperature difference and high particle concentration in the original flue gas, so it is the most important area to remove particles of each size. The dedusting performance of WFGD can be optimized by increasing the temperature difference between gas and liquid, the relative velocity of gas and liquid, and the ratio of liquid to gas.
The synergetic effect of wet flue gas desulfurization(WFGD) system can further reduce the emission of particulate matter from the coal-fired plants.Mathematical model and numerical method were established to describe the gas-liquid-solid three-phase movement in the tower, and the process of particle removal by spraying in WFGD system was simulated. The results show that the efficiency of particle removal increases with the increase of particle size. The major mechanism for capturing submicron particles is thermophoresis, and the region with large gas-liquid temperature difference is the main capturing area. Micron particles are captured mainly by inertial capture mechanism,and the capture efficiency of single droplet near the spray layers is the highest. Besides, the area near the flue gas inlet is with high concentration of droplets, large temperature difference and high particle concentration in the original flue gas, so it is the most important area to remove particles of each size. The dedusting performance of WFGD can be optimized by increasing the temperature difference between gas and liquid, the relative velocity of gas and liquid, and the ratio of liquid to gas.
引文
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[21]李孔清.室内超细悬浮颗粒模型及算法研究[D].长沙:湖南大学,2007.Li Kongqing.Research on indoor fine suspension particle model and numerical simulation algorithm[D].Changsha:Hunan University,2007(in Chinese).
[22]Davenport H M,Peters L K.Field studies of atmospheric particulate concentration changes during precipitation[J].Atmospheric Environment(1967),1978,12(5):997-1008.
[23]Raj Mohan B,Jain R K,Meikap B C.Comprehensive analysis for prediction of dust removal efficiency using twin-fluid atomization in a spray scrubber[J].Separation and Purification Technology,2008,63(2):269-277.
[24]Chate D M,Murugavel P,Ali K,et al.Below-cloud rain scavenging of atmospheric aerosols for aerosol deposition models[J].Atmospheric Research,2011,99(3-4):528-536.
[2]王翱.单液滴捕集细颗粒物的行为与机制研究[D].北京:清华大学,2016.Wang Ao.Research on the capture behavior and mechanism of fine particles by a single droplet[D].Beijing:Tsinghua University,2016(in Chinese).
[3]万益.湿式静电除尘水膜均布及细颗粒物强化脱除研究[D].杭州:浙江大学,2014.Wan Yi.Uniformity of water film and enhancement of fine particles removal in wet electrostatic precipitator[D].Hangzhou:Zhejiang University,2014(in Chinese).
[4]Wang Ao,Song Qiang,Tu Gongming,et al.Influence of flue gas cleaning system on characteristics of PM2.5emission from coal-fired power plants[J].International Journal of Coal Science&Technology,2014,1(1):4-12.
[5]Yao Qiang,Li S Q,Xu H W,et al.Studies on formation and control of combustion particulate matter in China:a review[J].Energy,2009,34(9):1296-1309.
[6]赵磊,周洪光.超低排放燃煤火电机组湿式电除尘器细颗粒物脱除分析[J].中国电机工程学报,2016,36(2):468-473.Zhao Lei,Zhou Hongguang.Particle removal efficiency analysis of WESP in an ultra low emission coal-fired power plant[J].Proceedings of the CSEE,2016,36(2):468-473(in Chinese).
[7]史文峥,杨萌萌,张绪辉,等.燃煤电厂超低排放技术路线与协同脱除[J].中国电机工程学报,2016,36(16):4308-4318.Shi Wenzheng,Yang Mengmeng,Zhang Xuhui,et al.Ultra-low emission technical route of coal-fired power plants and the cooperative removal[J].Proceedings of the CSEE,2016,36(16):4308-4318(in Chinese).
[8]潘丹萍,吴昊,鲍静静,等.电厂湿法脱硫系统对烟气中细颗粒物及SO3酸雾脱除作用研究[J].中国电机工程学报,2016,36(16):4356-4362.Pan Danping,Wu Hao,Bao Jingjing,et al.Removal effect of Wet Flue Gas Desulfurization System on fine particles and SO3 acid mist from coal-fired power plants[J].Proceedings of the CSEE,2016,36(16):4356-4362(in Chinese).
[9]王珲,宋蔷,姚强,等.电厂湿法脱硫系统对烟气中细颗粒物脱除作用的实验研究[J].中国电机工程学报,2008,28(5):1-7.Wang Hui,Song Qiang,Yao Qiang,et al.Experimental study on removal effect of Wet Flue Gas Desulfurization System on fine particles from a coal-fired power plant[J].Proceedings of the CSEE,2008,28(5):1-7(in Chinese).
[10]Wu Hao,Yang Linjun,Yan Jinpei,et al.Improving the removal of fine particles by heterogeneous condensation during WFGD processes[J].Fuel Processing Technology,2016,145:116-122.
[11]Bao Jingjing,Yang Linjun,Yan Jinpei,et al.Experimental study of fine particles removal in the desulfurated scrubbed flue gas[J].Fuel,2013,108:73-79.
[12]Yang Linjun,Bao Jingjing,Yan Jinpei,et al.Removal of fine particles in wet flue gas desulfurization system by heterogeneous condensation[J].Chemical Engineering Journal,2010,156(1):25-32.
[13]Fan Fengxian,Yang Linjun,Yan Jinpei,et al.Experimental investigation on removal of coal-fired fine particles by a condensation scrubber[J].Chemical Engineering and Processing:Process Intensification,2009,48(8):1353-1360.
[14]朱杰,许月阳,姜岸,等.超低排放下不同湿法脱硫协同控制颗粒物性能测试与研究[J].中国电力,2017,50(1):168-172.Zhu Jie,Xu Yueyang,Jiang An,et al.Test and study on performance of wet FGD coordinated particulate matter control for ultra-low pollutants emission[J].Electric Power,2017,50(1):168-172(in Chinese).
[15]Wang Ao,Song Qiang,Yao Qiang.Thermophoretic capture of submicron particles by a droplet[J].Atmospheric Environment,2016,147:157-165.
[16]Pranesha T S,Kamra A K.Scavenging of aerosol particles by large water drops:1.Neutral case[J].Journal of Geophysical Research:Atmospheres,1996,101(D18):23373-23380.
[17]Carotenuto C,Di Natale F,Lancia A.Wet electrostatic scrubbers for the abatement of submicronic particulate[J].Chemical Engineering Journal,2010,165(1):35-45.
[18]Marocco L,Inzoli F.Multiphase euler-lagrange CFDsimulation applied to wet flue gas Desulphurisation technology[J].International Journal of Multiphase Flow,2009,35(2):185-194.
[19]Pilat M J,Prem A.Calculated particle collection efficiencies of single droplets including inertial impaction,brownian diffusion,diffusiophoresis and thermophoresis[J].Atmospheric Environment(1967),1976,10(1):13-19.
[20]韩小梅.燃煤电站湿法烟气脱硫的颗粒物脱除效果[J].环境工程学报,2017,11(3):1653-1659.Han Xiaomei.Particulate removal efficiency of wet flue gas desulfurization in a coal-fired power plant[J].Chinese Journal of Environmental Engineering,2017,11(3):1653-1659(in Chinese).
[21]李孔清.室内超细悬浮颗粒模型及算法研究[D].长沙:湖南大学,2007.Li Kongqing.Research on indoor fine suspension particle model and numerical simulation algorithm[D].Changsha:Hunan University,2007(in Chinese).
[22]Davenport H M,Peters L K.Field studies of atmospheric particulate concentration changes during precipitation[J].Atmospheric Environment(1967),1978,12(5):997-1008.
[23]Raj Mohan B,Jain R K,Meikap B C.Comprehensive analysis for prediction of dust removal efficiency using twin-fluid atomization in a spray scrubber[J].Separation and Purification Technology,2008,63(2):269-277.
[24]Chate D M,Murugavel P,Ali K,et al.Below-cloud rain scavenging of atmospheric aerosols for aerosol deposition models[J].Atmospheric Research,2011,99(3-4):528-536.