烟气横掠螺旋槽管束灰粒沉积特性的数值模拟

Numerical simulation on particle deposition in flue gas flowing across spirally corrugated tubes in aligned arrangement

为研究烟气中飞灰颗粒在螺旋槽管束壁面上的沉积特性,颗粒相采用离散相模型,气相采用k-ε湍流模型构建烟气横掠螺旋槽管束的气固两相流动模型,结合用户自定义函数(灰粒沉积模型)开展数值模拟研究.比较和分析飞灰颗粒在螺旋槽管束和光管管束壁面上的沉积特性和差异,并讨论两相流动参数、管束结构参数对灰粒沉积速率的影响.结果表明:烟气流速为7~10 m·s-1时,螺旋槽管束壁面上的灰粒沉积速率比光管减小5%左右;流速大于10 m·s-1时灰粒在螺旋槽管壁上的灰粒沉积速率与光管无明显差异;较大粒径的灰粒易沉积,灰粒质量浓度越高,灰粒沉积速率越大;灰粒沉积速率与管束的纵向节距成正比,与横向节距、螺距以及槽深成反比,横向节距和螺距对沉积速率的影响相对明显.

To investigate the particle deposition in flue gas on the surface of spirally corrugated tubes,the numerical simulation was carried out by discrete phase model and user-defined function of particles deposition model to predict gas-solid two phase flow across spirally corrugated tubes. The particle deposition rate and the difference between bare tubes and spirally corrugated tubes were analyzed and discussed. The effects of gas-solid two phase flow parameters and tube bundles configuration on the particle deposition rate were also investigated. The results show that compared to the bare tubes,the deposition rate for spirally corrugated tubes is decreased by about 5% when the gas flow velocity is in the range from 7 to 10 m·s-1. However,when the flue gas flow velocity is beyond 10 m·s-1,there is no obvious difference between spirally corrugated tubes and bare tubes. The deposition rate is increased with the increasing of particle diameter and particle concentration in flue gas. The deposition rate is proportional to longitudinal space and inversely proportional to transverse space,pitch and groove depth.The effects of transverse space and pitch on the particles deposition rate are more obvious than that of groove depth.