颗粒轨道模型用于烟气脱硫喷淋塔两相流数值模拟

Particle Trajectory Model Used in Numerical Simulation of Flue Gas Desulfurization Spray Tower

以FLUENT软件为计算工具,采用Euler-Lagrange方法模拟喷淋塔内部气液两相流动.气相用标准k-ε湍流模型描述,喷淋液滴用颗粒轨道模型描述.综合考虑颗粒受力分析、颗粒湍流扩散以及气液两相耦合3方面影响因素对颗粒轨道模型进行设置,从液滴粒径分布、液滴出口速度、喷淋夹角3个方面对喷嘴射流源进行精确定义.模拟结果表明:喷淋塔内轴向气速分布均匀;中空锥形的喷嘴设计使喷淋液形成伞状雨帘,有效防止烟气短流;塔内液滴浓度分布存在中间高、边缘低的问题,可通过改进喷嘴布置方案加以改进;颗粒轨道模型能够较好地预测喷淋塔内两相流动.

The commercial computational fluid dynamics （CFD） software FLUENT is used to predict the two-phase flow in a flue gas desulfurization （FGD） spray tower. The Euler-Lagrange method is used, in which the gas flow is described with standard k-ε turbulence model, and the motion of the liquid droplets is described with the particle trajectory model. The procedure of model definition, including force analysis of liquid particle, gas turbulent dispersion and the gas-liquid coupling method, is presented. The results show that the uniformity of axial gas velocity in the spray tower is satisfactory, and the hollow spray nozzle used in the tower can efficiently prevent short-circuiting of the flue gas. The concentration of liquid droplets in the central region is higher than near the wall, and this problem can be solved by optimizing the arrangement of the spray nozzles near the wall. Model predictions for particle trajectory are shown to be in good agreement with experimental results, and the particle trajectory model can predict the two-phase flow in the spray tower successfully.