S/P模式计算的冷却塔烟气抬升高度敏感性试验

德国VDI3784的S/P模式为三维流体动力学积分模式,其方程主要描述了无穷小体积元素的质量、动量、静态污染物质量浓度及能量的守恒。利用德国模式进行了冷却塔烟气排放不同参数、不同大气条件下烟气抬升高度的敏感性试验。结果表明：在影响烟气抬升高度的3个气象要素（风速、气温和湿度）中,风速和气温的变化对结果影响较大,而湿度影响较小。在D类稳定度,当环境风速从0.1 m/s增加到15.0 m/s时,抬升高度从711.7 m变为38.5 m。随着环境温度的升高,抬升高度明显单调变小;当稳定度为A类,环境温度从10升到40时,烟气抬升最大高度从688.9 m降低到45.1 m,降低了14倍多。而环境湿度的变化,对抬升高度的影响不是很明显。对于E类稳定度和F类稳定度,当环境湿度从20%增加到70%,最大抬升高度分别从115.3 m和84.6 m降到112.9 m和81.7 m,分别降低了3.43%和2.08%。在影响烟气抬升高度的其他3个因素（凉水塔直径、烟气出口速度和混合气体温度）中,混合气体温度的变化对结果影响较大,而凉水塔直径和烟气出口速度的影响较小。在各类稳定度条件下,当出口温度从20变到90时,烟气抬升高度增加1.2—13.3倍;在各类稳定度条件下,当凉水塔直径从30 m变到90 m,烟气抬升高度仅增加0.63—1.40倍;在各类稳定度条件下,当出口速度从2.5 m/s变到8.0 m/s,烟气抬升高度增加了0.24—0.74倍。

Sensitivity test of uplifted height of flue gas from cooling tower based on S/P model

The S/P model from German VDI3784 is a three-dimensional liquid dynamic integral model.Mass and momentum of infinitesimal element,mass concentration of static pollutant and energy balance were described.The sensitivity of uplifted height of flue gas from cooling tower was tested by the S/P model under different parameters and atmospheric conditions.The results indicate that wind speed,air temperature and humidity could influence the uplifted height of flue gas,especially wind speed and air temperature.Under the stabilization of ＂D＂ type,the uplifted height changes from 711.7 m to 38.5 m when wind speed increases from 0.1 m/s to 15.0 m/s.In addition,the uplifted height diminishes distinctly with rising of environmental temperature.Under the stabilization of ＂A＂ type,the uplifted height reduces from 688.9 m to 45.1 m when environmental temperature increases from 10 ℃ to 40 ℃,and it decreases more than 14 times.However,the effect of environmental humidity on the uplifted height is not significant.Under the stabilization of ＂E＂ and ＂F＂ types,the uplifted heights decrease from 115.3 m and 84.6 m to 112.9 m and 81.7 m respectively when environmental humidity increases from 20% to 70%,and both decrease 3.43% and 2.08%.On the other hand,the diameter of cooling tower,gas speed and mix gas temperature at the exit could also influence the uplifted height of flue gas,especially mix gas temperature.Under the various stabilization conditions,the uplifted height of flue gas increases 1.2-13.3 times,0.63-1.40 times and 0.24-0.74 times when mix gas temperature at the exit changes from 20 ℃ to 90 ℃,the diameter of cooling tower from 30 m to 90 m and gas speed at the exit from 2.5 m/s to 8 m/s,respectively.