喷射雾滴烟气流动蒸发特性
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摘要
电站锅炉烟气脱硫废水喷入烟道蒸发是电厂废水零排放最经济可行的技术途径之一。针对该技术实际应用中存在的在烟道壁面上结垢腐蚀问题,以单台300 MW机组为对象,将针对连续相烟气的湍流流动传热欧拉方法,以及离散相雾化液滴群流动蒸发的拉格朗日方法相结合,建立物理数学模型。通过数值模拟方法,研究脱硫废水喷射雾滴在烟气中的流动蒸发特性及其影响因素,获得不同运行条件下喷雾的扩散范围和液滴在烟气内的运动轨迹。结果表明:烟气温度越高、雾化液滴群的直径越小,其完全蒸发所需的时间和距离越短;采用多喷嘴小流量的布置方式可以提高雾化液滴群的蒸发质量;喷嘴喷射方向的选择应该保证雾化液滴群与烟气相对运动增强的同时,保证液滴能在规定距离和时间内完全扩散并与烟气进行充分接触和换热,实现雾化液滴群蒸发质量的最大化;而液滴初速度、喷嘴的喷射全锥角、烟气速度对蒸发率的影响不大。研究结果可为火电厂脱硫废水烟气蒸发的工艺设计及性能调控提供依据。
Spraying flue gas desulfurization(FGD) wastewater into flue duct is an economical and feasible technology to achieve zero discharge in power plant. To deal with the scale and corrosion on flue walls that exist in the practical application of this technology, the physical and mathematical models are established based on a 300 MW power plant. The Eulerian-Lagrangian approach is used to describe the thermo-fluid behavior of FGD wastewater in flue gas, by which the turbulent flow heat transfer of flue gas is described by the Eulerian framework and theevaporation of water droplets is described using the Lagrangian framework. By numerical simulation the flow evaporation characteristics and influencing factors of FGD wastewater droplets sprayed in flue gas were studied. The diffusion range and trajectories of atomized droplets under different operating conditions were obtained. The following results were gained:higher flue gas temperature and smaller diameter of the atomized droplets contribute to shorter time and distance for complete evaporation. Besides, the arrangement of small-flow-multi nozzles can improve the evaporation of atomized droplets. The spray direction must ensure that the relative movement between atomized droplets and flue gas is enhanced, while the droplets can fully diffuse and contact with the flue gas within a specified distance and time, achieving maximum evaporation of the atomized droplets. However, the initial velocity of atomized droplets, the spray full cone angle of nozzles, and the velocity of flue gas have little influence on atomized droplets evaporation. These research results can provide process design and performance regulation of the FGD wastewater evaporation in flue duct of thermal power plants.
Spraying flue gas desulfurization(FGD) wastewater into flue duct is an economical and feasible technology to achieve zero discharge in power plant. To deal with the scale and corrosion on flue walls that exist in the practical application of this technology, the physical and mathematical models are established based on a 300 MW power plant. The Eulerian-Lagrangian approach is used to describe the thermo-fluid behavior of FGD wastewater in flue gas, by which the turbulent flow heat transfer of flue gas is described by the Eulerian framework and theevaporation of water droplets is described using the Lagrangian framework. By numerical simulation the flow evaporation characteristics and influencing factors of FGD wastewater droplets sprayed in flue gas were studied. The diffusion range and trajectories of atomized droplets under different operating conditions were obtained. The following results were gained:higher flue gas temperature and smaller diameter of the atomized droplets contribute to shorter time and distance for complete evaporation. Besides, the arrangement of small-flow-multi nozzles can improve the evaporation of atomized droplets. The spray direction must ensure that the relative movement between atomized droplets and flue gas is enhanced, while the droplets can fully diffuse and contact with the flue gas within a specified distance and time, achieving maximum evaporation of the atomized droplets. However, the initial velocity of atomized droplets, the spray full cone angle of nozzles, and the velocity of flue gas have little influence on atomized droplets evaporation. These research results can provide process design and performance regulation of the FGD wastewater evaporation in flue duct of thermal power plants.
引文
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[15]周正,吴畏,郑昕,等.喷嘴雾化特性及脱硫废水蒸发数值模拟[J].化工进展,2018,37(1):32-38.
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[20]Kim H,Sung N.The effect of ambient pressure on the evaporation of a single droplet and a spray[J].Combustion&Flame,2003,135(3):261-270.
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[22]张子敬,汪建文,高艺,等.燃煤电厂脱硫废水烟气蒸发特性流场模拟[J].煤炭学报,2015,40(3):678-683.
[23]马双忱,柴峰,吴文龙,等.脱硫废水烟道喷雾蒸发的数值模拟[J].计算机与应用化学,2016,33(1):47-53.
[24]Padoin N,Dal’ToéA T O,Rangel L P,et al.Heat and mass transfer modeling for multicomponent multiphase flow with CFD[J].International Journal of Heat&Mass Transfer,2014,73(4):239-249.
[25]Alkhedhair A,Jahn I,Gurgenci H,et al.Numerical simulation of water spray in natural draft dry cooling towers with a new nozzle representation approach[J].Applied Thermal Engineering,2016,98:924-935.
[26]Alkhedhair A,Gurgenci H,Jahn I,et al.Numerical simulation of water spray for pre-cooling of inlet air in natural draft dry cooling towers[J].Applied Thermal Engineering,2013,61(2):416-424.
[27]张志荣.火电厂湿法烟气脱硫废水喷雾蒸发处理方法关键问题研究[D].重庆:重庆大学,2011.
[28]吴帅帅,李红智,陈鸿伟,等.脱硫废水烟道喷雾蒸发过程的数值模拟[J].热力发电,2015,44(12):31-36.
[2]施云芬,王旭晖.湿法烟气脱硫废水处理研究进展[J].工业水处理,2015(12):14-17.
[3]虞钢,马浩栋.石灰石-石膏湿法烟气脱硫废水处理技术探讨[J].山东工业技术,2017(9):14.
[4]庄常灿.燃煤电厂锅炉烟气湿法脱硫废水深度处理工艺选择[J].低碳世界,2017(23):96-97.
[5]王可辉,蒋芬,徐志清,等.燃煤电厂脱硫废水零排放工艺路线研究[J].工业用水与废水,2016,47(1):9-12.
[6]凌珊珊,马杰.关于烟气脱硫废水“零排放”技术应用分析[J].化工管理,2017(14):164-165.
[7]佘晓利,潘卫国,郭士义,等.燃煤电厂湿法烟气脱硫废水零排放技术进展[J].应用化工,2018(1):160-164.
[8]任丹丹,冯罗澍,陈颖.大型燃煤电厂脱硫废水烟气利用技术研究[J].浙江电力,2018,37(3):82-85.
[9]李东.火力发电厂烟气脱硫废水处理分析[J].中国新技术新产品,2018(8):129-130.
[10]谈宾宾,李超.火力发电厂烟气脱硫废水处理工艺研究[J].化工管理,2016,(36):146.
[11]禾志强,祁利明.火力发电厂烟气脱硫废水处理工艺[J].水处理技术,2010,36(3):133-135.
[12]Deng J J,Pan L M,Chen D Q,et al.Numerical simulation and field test study of desulfurization wastewater evaporation treatment through flue gas[J].Water Science&Technology A Journal of the International Association on Water Pollution Research,2014,70(7):1285-1291.
[13]渠慧英.火电厂废水综合利用技术经济分析[J].环境与发展,2018,30(2):31-34.
[14]韦飞,刘景龙,王特,等.燃煤电厂脱硫废水零排放技术探究[J].水处理技术,2017,43(6):34-36.
[15]周正,吴畏,郑昕,等.喷嘴雾化特性及脱硫废水蒸发数值模拟[J].化工进展,2018,37(1):32-38.
[16]Hou Y,Tao Y,Huai X,et al.Numerical characterization of multi-nozzle spray cooling[J].Applied Thermal Engineering,2012(39):163-170.
[17]刘秋生.烟气脱硫废水“零排放”技术应用[J].热力发电,2014(12):114-117.
[18]胡石,丁绍峰,樊兆世.燃煤电厂脱硫废水零排放工艺研究[J].洁净煤技术,2015(2):129-133.
[19]Ma S,Chai J,Chen G,et al.Research on desulfurization wastewater evaporation:Present and future perspectives[J].Renewable&Sustainable Energy Reviews,2016(58):1143-1151.
[20]Kim H,Sung N.The effect of ambient pressure on the evaporation of a single droplet and a spray[J].Combustion&Flame,2003,135(3):261-270.
[21]Nasser Ashgriz.Handbook of atomization and sprays[M].New York:Springer-Verlag New York inc.,2011:869-879.
[22]张子敬,汪建文,高艺,等.燃煤电厂脱硫废水烟气蒸发特性流场模拟[J].煤炭学报,2015,40(3):678-683.
[23]马双忱,柴峰,吴文龙,等.脱硫废水烟道喷雾蒸发的数值模拟[J].计算机与应用化学,2016,33(1):47-53.
[24]Padoin N,Dal’ToéA T O,Rangel L P,et al.Heat and mass transfer modeling for multicomponent multiphase flow with CFD[J].International Journal of Heat&Mass Transfer,2014,73(4):239-249.
[25]Alkhedhair A,Jahn I,Gurgenci H,et al.Numerical simulation of water spray in natural draft dry cooling towers with a new nozzle representation approach[J].Applied Thermal Engineering,2016,98:924-935.
[26]Alkhedhair A,Gurgenci H,Jahn I,et al.Numerical simulation of water spray for pre-cooling of inlet air in natural draft dry cooling towers[J].Applied Thermal Engineering,2013,61(2):416-424.
[27]张志荣.火电厂湿法烟气脱硫废水喷雾蒸发处理方法关键问题研究[D].重庆:重庆大学,2011.
[28]吴帅帅,李红智,陈鸿伟,等.脱硫废水烟道喷雾蒸发过程的数值模拟[J].热力发电,2015,44(12):31-36.