【摘要】 通过计算流体力学方法对大型脱硫塔内不同喷淋层的运行方式进行数值仿真,并和工程现场数据作对比.模拟采用欧拉-拉格朗日方法,并考虑了气液两相间的各种耦合作用,以及气相湍流速度脉动的随机特征对颗粒相的影响.主要结论如下:①各喷淋工况下,在烟气入口高度范围内,截面平均气流总速度和水平向(水平烟气方向)分速度均达到峰值后快速衰减,其中后者至底层喷淋处趋于零;截面平均垂直速度分量沿塔高方向的变化曲线几乎完全重合,且在整个烟气入口高度范围内单调线性增加;②各喷淋方案中,仅底层喷淋时塔内的气相温度场和水蒸气浓度场最不均匀,烟气出口截面的平均温度明显高于其他工况,出口截面的平均湿度也未达到饱和;而仅顶层喷淋时,上述不均匀性明显减小;③各喷淋方案(除仅底层喷淋外),截面平均气相温、湿度沿塔高方向变化曲线的极值都出现在烟气入口高度的下部1/4处;随着喷淋层数增多,温度曲线的最大值降低,湿度曲线的最低值则升高;④仅底层喷淋时的蒸发水量为4层喷淋全部开启时的4/5;而仅顶层喷淋时的蒸发水量和开启更多喷淋层时已没有明显差别.各喷淋方案中,仅顶层喷淋时的蒸发比率最高.更多还原

【Abstract】 The operation modes of spraying layers in the large scale desulphurization tower with four spraying layers were investigated by computational fluid dynamics numerical simulation. The Euler-Lagrange approach was adopted and the inter-exchanges of momentum,mass and energy between the gas and liquid phase were fully studied; the effect of instantaneous turbulent velocity fluctuations on the particle trajectories was also taken into account through the use of stochastic methods. The simulation results were also validated via actual on-site data. The main results are as follow:(1) for all spraying modes,the area-weighted mean total velocity and its horizontal component of the gas phase on the horizontal cross-sections reach to their peak values inside the height of the flue gas inlet and then decline quickly,the horizontal component almost decreases to 0 when the flue gas comes to the bottom spraying layer. Meanwhile,the curves of area-weighted mean vertical velocity components of all spraying modes almost overlap completely along the absorption tower,and inside the height of the flue gas inlet,they show perfect mono-tonous linear increase.(2) Among all spraying modes,the most non-uniformity in the temperature field and water vapor field of the flue gas occurs when only bottom spraying layer operating. In addition,in such spraying mode,the area-weighted mean temperature on the flue gas outlet is much higher than the other spraying modes,and the area-weighted mean humidity on the flue gas outlet is not saturated. Whereas,the above-mentioned non-uniformity is alleviated obviously when only top spraying layer operating.(3) For all spraying modes except only bottom spray-ing layer operating,the curve extremums of area-weighted mean temperature and humidity of the gas phase on the horizontal cross-sections along the absorption tower are all located within the lower quarter height of the flue gas inlet. With the increase of spraying layers,the maximum values of the above-mentioned temperature curves decrease,while the minimum values of the humidity curves increase.(4) When only bottom spraying layer operates,the evaporation water quantity accounts for four fifths the value when all the four spraying layers operating. There is no significant difference in evaporation water quantity between only top spraying layer mode and other multiple layers modes. Among all the spraying modes,the highest evaporation ratio is found when only top spraying layer adopted.更多还原