湿法脱硫塔内脱硫浆液运动特性

Motion characteristics of gypsum slurry in wet-type desulphurization tower

为了分析湿法脱硫塔运行中所存在的问题,以600 MW机组湿法烟气脱硫喷淋塔为研究对象,使用数值模拟方法对塔内两相流场进行研究,获得湿法脱硫塔内流场分布以及不同粒径液滴的运动轨迹、逃逸率及停留时间。研究结果表明:2 mm以上粒径液滴在塔内分布较均匀,1 mm以下粒径液滴运动受流场影响明显,使其数量分布集中于塔内低速区;当液滴粒径小于0.2 mm时,逃逸率几乎为100%;当液滴粒径大于0.2 mm时,液滴逃逸率曲线随着粒径增大迅速减小,直至当逃逸率为20%时,逃逸率曲线开始缓慢下降;随着粒径的增大,液滴停留时间曲线具有峰值,且该峰值粒径也是在逃逸率曲线中开始缓慢下降处的粒径;流场不均匀性导致0.8 mm以下粒径液滴逃逸率降低,0.8 mm以上粒径液滴逃逸率增大,同时导致下落液滴停留时间减少。

The 600 MW unit desulphurization spray tower was investigated to analyze the problems existing in the wet desulfurization tower. The trajectories, escape rate and residence time of droplets of different diameters in the spray tower were obtained by numerical simulation methods for the gas-solid two-phase flow in the spray tower. The results show that the droplets greater than 2 mm are distributed uniformly in the tower, while the motion of droplets less than 1 mm in diameter is significantly influenced by the flow field and these droplets mainly concentrate on the low velocity zone. The escape rate reaches about 100% for the droplets less than 0.2 mm in diameter, while it sharply decreases with diameter with respect to those greater than 0.2 mm. Nevertheless, the decline speed slows down when the escape rate is less than 20%. With the increase of diameter, there is a peak on the curve of residence time, and the droplet diameter corresponding to the peak value is exactly the point when the decline speed begins to slow down on the curve of escape rate. The inhomogeneity of the flow field leads to the decrease of escape rate for droplets less than 0.8 mm and the increase of escape rate for droplets greater than 0.8 mm. Meanwhile, the residence time is also reduced.