脱硫塔流场结构优化及速度不均匀度分析

Optimization of flow field structure and analysis on velocity nonuniformity of the desulfurization tower

脱硫塔内浆液喷淋均匀程度,对烟气分布及脱硫反应有重要影响,研究脱硫塔内的流场速度不均匀性及结构优化对提高脱硫效率具有重要意义。为此,提出不均匀度的量化指标,建立机组负荷与脱硫效率的关系,优化塔内结构,采用数值模拟方法分析不均匀度随脱硫效率的变化趋势。研究了入口速度为3.0、3.4、3.7和4.0 m/s的脱硫塔内部流场,增加入口导叶,并利用倾斜式格栅均流板进行流场优化,分析塔内不同高度的水平截面和垂直截面的速度分布,对比优化前后流场动压沿垂直方向的变化。结果表明,波动中负荷与脱硫效率呈明显负相关,脱硫效率与不均匀度的变化趋势基本相同,各工况下,优化后中间区域烟气不均匀度降低10%,中部主要脱硫反应区的动压差异减少70%左右,出口速度提高0.1~0.2 m/s,出口湍动能降低最高50%。优化方案能有效改善塔内烟气速度分布,提高不同入口速度下的流场均匀性和烟气脱硫效率,降低浆液被裹挟出塔的可能性,减少烟气流动阻力和运行成本。

The uniformity of slurry spray in the desulfurization tower has an important influence on the distribution of flue gas and the desulfurization reaction.It is of great significance to study the velocity inhomogeneity of flow field and structure optimization in the desulfurization tower to improve the desulfurization efficiency.Therefore,the quantitative analysis index unevenness was put forward.The relationship between unit load and desulfurization efficiency was established.The inner structure of the tower was optimized.Numerical analysis was used to analyze the variation trend of heterogeneity with desulfurization efficiency.The internal flow field of desulfurization tower with inlet velocity of 3.0,3.4,3.7 and 4.0 m/s was studied.Inlet guide vanes were added and flow field optimization was carried out by using inclined grid flow homogenizing plate.The velocity distributions of horizontal and vertical sections at different heights in the tower were analyzed,and the dynamic pressure changes along the vertical direction were compared.The results show that the load and desulfurization efficiency shows a significant negative correlation in the fluctuation,and the variation tends of desulfurization efficiency and velocity unevenness are basically the same,under all working conditions.The velocity unevenness ω in the middle area decreases by 10%,the dynamic pressure difference of the main desulfurization reaction area decreases by about 70%,and the outlet velocity increases by 0.1-0.2 m/s.The optimization structure could improve the velocity distributions inside the FGD tower,increasing desulfurization efficiency and flow uniformity.Also,it could reduce the possibility of slurry being wrapped out of the tower and help reduce the flow resistance and running cost.