旋流烟气下喷雾干燥脱硫塔中气液分布及混合特性的数值研究

Numerical Study on Gas-Liquid Distribution and Mixing Characteristics of Spray Drying Desulfurization Tower Under Swirling Flue Gas

针对喷雾干燥脱硫塔中的混合问题,采用离散颗粒相模型(DPM)对塔内液滴群径向位移、液滴群散布及气液混合进行数值分析,重点考察烟气入口旋流强度S和液滴群平均粒径d的影响。结果表明:烟气入口旋流强度从0增加到0.5时,液滴群径向位移先缓慢减小后迅速增大;液滴群平均粒径从65μm增加至150μm时,液滴群径向位移近似线性增大;随着烟气入口旋流强度和液滴群平均粒径增加,液滴群散布程度呈先增加后减小的趋势;合适的烟气入口旋流强度和液滴群平均粒径能有效减小气液混合度,显著改善气液混合效果;烟气入口旋流强度为0.3时,液滴群径向位移和气液混合度最小,与无旋流相比,分别平均减小了约20%和34.45%;液滴群平均粒径为150μm时,液滴群散布程度最大,气液混合度最小,与液滴群平均粒径65μm相比,气液混合度平均减小了约51.85%。

Focusing on the mixing problem in the spray drying desulfurization tower,the discrete phase model(DPM)was used to numerically analyze the radial displacement of the droplet group,the droplet group dispersion,and the gas-liquid mixing,and the effects of the flue gas swirl intensity(S)and the average droplet size(■)were particularly studied.Results show that with the flue gas swirl intensity increasing from 0 to 0.5,the radial displacement of the droplet group decreases slowly at first then increases rapidly.The radial displacement of the droplet group presents a linear augment with an increase of average droplet size from 65μm to 150μm.The droplet group dispersion increases at the beginning and then decreases with the increase of flue gas swirl intensity and average droplet size.The appropriate flue gas swirl intensity and average droplet size can effectively reduce the gas-liquid mixing variance and thus significantly improve gas-liquid mixing.When the swirl intensity is 0.3,the radial displacement of the droplet group and the gas-liquid mixing variance are the smallest.Compared with the absence of a swirl scenario,the radial displacement of the droplet group is reduced by about 20%on average,and the gas-liquid mixing variance is reduced by about 34.45%on average.When the average droplet size is 150μm,the droplet group dispersion degree reaches the maximum,while the gas-liquid mixing variance is the smallest.Compared with the average droplet size of 65μm,the gas-liquid mixing variance decreases by about 51.85%on average.