基于风洞实验的冷却塔空腔区范围影响因素研究
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摘要
目的基于火电厂采用"烟塔合一"排烟方式时可能由于污染物下洗造成"空腔区"内地面高浓度等问题,分析空腔区范围,以科学设置环境防护距离。方法采用相似理论,将10个"烟塔合一"火电厂及地形按几何比缩小至风洞实验室内,通过测量冷却塔后方湍流度,并对比背景湍流度的方法,分析不同冷却塔形状以及不同下垫面条件下冷却塔空腔区的尺寸。结果空腔区的高度、宽度与冷却塔高宽比存在正相关性,山地地形更有利于湍涡耗散,而使空腔区范围较平坦地形更小,厂区内大型建筑物位置会对冷却塔空腔区的范围产生影响。试验分析得出,冷却塔空腔区范围基本在冷却塔高度的2倍以内,高宽比越大,则空腔区范围越小,地形越复杂,空腔区范围越小。结论火电厂采用"烟塔合一"排烟方式时,建议优先选择高宽比大的塔型,以降低排烟冷却塔对周围环境影响的可能性。
Objective To analyze the range of the cavity area for setting the environmental protection distance scientifically in view that thermal power plant which use the "cooling tower with flue gas injection" may have the high concentration of the ground in the "cavity area" which caused by the downwash of the flue gas. Methods With the similar theory, 10 thermal power plants model with "cooling tower with flue gas injection" were shrank into the wind tunnel laboratory, and the method of measuring and comparing the turbulence and background turbulence was used to get the size of cavity area of the cooling tower with different shapes and underlying surface conditions. Results There was a positive correlation between the height and width of the cavity area and the aspect ratio of the cooling tower. In addition, the mountainous terrain was more favorable for the vortex dissipation, so that the cavity area was smaller than the flat terrain. The position of large buildings in the plant could affect the range of the cavity area of cooling tower. The cavity area of the cooling tower was basically within 2 times of the height of the cooling tower. The larger the aspect ratio was, the smaller the range of the cavity area was. Conclusion It is recommended to give priority to the use the "cooling tower with flue gas injection" of large aspect ratio for thermal power plants to reduce the possibility of the flue gas affecting the surrounding environment.
Objective To analyze the range of the cavity area for setting the environmental protection distance scientifically in view that thermal power plant which use the "cooling tower with flue gas injection" may have the high concentration of the ground in the "cavity area" which caused by the downwash of the flue gas. Methods With the similar theory, 10 thermal power plants model with "cooling tower with flue gas injection" were shrank into the wind tunnel laboratory, and the method of measuring and comparing the turbulence and background turbulence was used to get the size of cavity area of the cooling tower with different shapes and underlying surface conditions. Results There was a positive correlation between the height and width of the cavity area and the aspect ratio of the cooling tower. In addition, the mountainous terrain was more favorable for the vortex dissipation, so that the cavity area was smaller than the flat terrain. The position of large buildings in the plant could affect the range of the cavity area of cooling tower. The cavity area of the cooling tower was basically within 2 times of the height of the cooling tower. The larger the aspect ratio was, the smaller the range of the cavity area was. Conclusion It is recommended to give priority to the use the "cooling tower with flue gas injection" of large aspect ratio for thermal power plants to reduce the possibility of the flue gas affecting the surrounding environment.
引文
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[12]环境保护部环境工程评估中心.烟塔合一排烟方式火力发电项目大气环境影响研究报告[R].北京:环境保护部环境工程评估中心,2017.
[2]秦松波.烟塔合一技术[J].上海电力,2007(5):493-495.
[3]BUSCH D,HARTEB R,KRATZIG W,et al.New Natural Draft Cooling Tower of 200 m of Height[J].Eng Struct,2002,24(12):1509-1521.
[4]ROTH M,GERBER R,NIEPEL A.Commissioning and Operation of the World-wide Largest Natural Draught Wet Cooling Tower of a Lignite-fired Power Plant with Flue Gas Discharge[C]//Natural Draught Cooling Towers Pro-ceedings of the Fifth International Symposium on Natural Draught Cooling Towers.London:CRC Press,2004.
[5]林勇.烟塔合一技术特点和工程数据[J].环境科学研究,2005,18(1):35-39.
[6]SCHATZMANN M,LOHMEYER A,ORTNER G.Flue Gas Discharge from Cooling Towers.Wind Tunnel Inves-tigation of Building Downwash Effects on Ground-level Concentrations[J].Atmos Environ,1987,21(8):1713-1724.
[7]顾明.土木结构抗风研究进展及基础科学问题[C]//第七届全国风工程和空气动力学学术会议论文集.成都:西南交通大学,2006.
[8]崔克强,李浩.燃煤发电厂烟塔合一环境影响之一:烟气抬升高度的对比计算[J].环境科学研究,2005,18(1):27-30.
[9]崔克强,柴发合.燃煤发电厂烟塔合一环境影响之二:华能北京热电厂烟塔合一设计环境影响估算[J].环境科学研究,2005,18(1):31-34.
[10]莫华,刘思湄.燃煤电厂“烟塔合一”技术在环评技术评估中存在的问题与建议[J].电力环境保护,2009,25(3):48-50.
[11]CERMAK J E.Application of Fluid Mechanics to Wind Engineering,a Freeman Scholar Lecture[J].J Fluids En-gineering,1975,97:9-38
[12]环境保护部环境工程评估中心.烟塔合一排烟方式火力发电项目大气环境影响研究报告[R].北京:环境保护部环境工程评估中心,2017.
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