【作者】 张应彪；

【导师】 孙奉仲；

【作者基本信息】 山东大学 ， 热能工程， 2008， 硕士

【摘要】 随着人们生活水平的提高,人们对于生活环境的要求越来越高,噪音污染也逐渐受到人们的重视。在电厂中,噪音也成为重要的污染源之一,冷却塔淋水噪音成为重要的噪音源,由于有些电厂的位置比较特殊,冷却塔距离居民区较近,冷却塔噪音已经严重的影响了居民的日常生活,因此冷却塔降噪有很强的现实意义。在目前冷却塔降噪研究的基础上,本文以自然通风逆流湿式冷却塔为研究对象,建立了以淋水量和进风口高度等为主要参变量的雨区噪音产生和传播的数学模型,亦建立了工程实际中冷却塔外部区域噪音的衰减模型。并且采用了新的降噪方法——导风板降噪,并利用数值模拟的方法模拟了各种情况下冷却塔雨区及外部区域的噪音分布情况。本文以某300MW火电机组的冷却塔为例,首先对无导风板情况下无侧风和进风速度分别为中、高风速时的冷却塔噪音传播进行了数值计算;又对冷却塔加导风板后,不同的导风板数量和安装角度在风速为零、中、高风速工况下进行了数值计算,得到了不同工况下的噪音分布值。此外,作者还现场实地测量了冷却塔的噪音分布情况。计算表明,无导风板情况下,当无侧风时,冷却塔噪音传播形成了以冷却塔的中心为圆心,冷却塔径向距离为半径的圆状分布,冷却塔的噪音沿径向分布比较均匀;沿高度方向,随着高度增加,冷却塔的噪音值有所增加,这些与实际测量的情况基本一致。当有侧风时,冷却塔的噪音传播分布不规律,在风比较集中的地方噪音也较集中,而且随着风速的增加,沿高度方向的冷却塔噪音值先增大后减小。冷却塔的周向加导风板后,无侧风时几乎对噪音分布没有影响;有侧风时,由于导风板对于进风的引导作用和出风的阻挡作用,在冷却塔的雨区形成了漩涡流,噪音沿进风的传播方向分布。冷却塔整个雨区噪音分布不均匀,在出风口处噪音集中,噪音值较高。36块导风板时,对导风板角度分别为30、45、60、90度进风速度分别为中风速和高风速的情况下噪音值的分布进行模拟,90度角时噪音值和无导风板时几乎一致,其余安装角度下噪音值出现了降低。此外导风板的安装改变了倍频程噪音在各频率段的分布情况,也实现了降噪的目的。在导风板角度同为30度时,对导风板的数量为12、36、90时的噪音分布进行比较,90块板时降噪效果最好,12块板时最差,36块板时居中,说明随着导风板数量增加,降噪效果明显。本文为了反映冷却塔在加导风板后是否对冷却塔运行的经济性产生影响,作者取进风量作为衡量标准,对不同情况下的进风量进行简单计算。通过对计算结果的比较,加导风板后所有情况的进风量大于未加导风板时的通风量;随着导风板安装角度的增加进风量增加;随着进风速度的增加,进风量增加。不同的导风板数量时,数量依次为12、36、90时,进风量先增大后减小。说明降噪最佳和运行经济性的最佳二者不可兼得。针对以上分析,本文初步提出了一些改进措施。本课题的研究成果对冷却塔降噪的研究提供了理论依据,并对工程实际中的冷却塔的降噪提供了新思路。更多还原

【Abstract】 With the improvement of people’s living standard,more and more people pay attention to the habitation and noise pollution.The noise of cooling tower is one of important noise fountainhead in power plant.The noise of some cooling towers nearby the residential place has affected residents’ daily life,so reducing of noise of cooling tower has very strong realistic meaning.Wet-style natural-ventilation cooling tower is regarded as the research object in the paper,and we set up the mathematical model of the noise’s producing and diffusing in rain area of cooling tower,and the main parametric variables include draining water content,height of air inlet and so on.We also set up the mathematical model of noise attenuation exterior of cooling tower in engineering.Leading broads are used for reducing the cooling tower noise in the paper as a new way.We get the distribution of noise interior and exterior of cooling tower by numerical simulation studied with Fluent.The cooling tower of 300MW thermal power is regarded as an example in this paper. At first,we get the noise distribution without leading broad and air inlet by simulation studied.Secondly,when we use the leading broads,we get the noise distribution when the amount and fixing angle of leading broad is different.Furthermore,the author measured the noise distribution in power plant.As we know from the calculation,the noise distribution of cooling tower is a circle when there is no air inlet and no leading broad.The centre of the circle is the centre of cooling tower,and the radius is radial distance.With the increasing of the height,the noise increase,and it matches practical case.Considering air inlet,the noise distribution of cooling tower is out of regularity.The noise is high where the wind is concentrated, and the noise increases first then decreases at height direction as the speed of air inlet increases.When install the leading broads,the noise is almost unchanged when there is no air inlet;when we consider air inlet,the air in rain area forms vortex flow because of the using of leading broads.The noise distribution of cooling tower accords to the wind distribution,and the noise is high at outlet of cooling tower.When the amount of leading broads is 36 and the speed of air inlet is 3m/s or 6m/s,we compare the noise level when the angle of fixing broad is 30、45、60and90.There is almost no noise lower when angle is 90 and the noise decreases when the angle is 30,45 and 60.The installation of leading board changed the octave noise in the frequency of the distribution, but also to achieve the purpose of the noise decreasing.When the fixing angle of leading broads is 30,we get the noise distribution in different amount.The amount of the broad is 12、36、90 respectively.Compared the noise distribution,that the amount of the broad is 90 has best effect,36 next,and 12 has west effect.So the effect can be greater as the amount of broad increases.We also calculate the amount of wind in order to reflect whether the broad affects the economy of cooling tower.Compared the calculation results,we find that the amount of wind which broad is used gets more.The amount of inlet wind increases with the increase of fixing angle of broad and the amount of inlet wind increases with the increase of wind speed.When the amount of broad is 12、36、90 respectively,the amount of inlet wind increases first and then decreases.So the best way of decreasing noise and the best economical of operation do not happen at the same time.We get some improving ways according to above analysis.The results of the paper afford theory basis for engineering,and we find a new way in decreasing noise of cooling tower.更多还原