立磨选粉机导流圈的数值模拟与分析

Numerical simulation and analysis on diversion circle of vertical mill classifier

为解决立磨改造中进入选粉机分级室气流速度过低的现象,设计了一种用于提升气流速度的导流圈.采用RNGk-ε湍流模型和DPM模型分别对立磨选粉机的气相流场和气固两相流场进行了数值模拟研究,对比分析了不同导流圈α角下的速度、压力分布云图和颗粒运行轨迹.模拟发现,导流圈α角过大,会限制进入选粉机分级室的气流速度;α角过小,则将增大立磨选粉机的压阻.结果表明:α角为60°时,大部分颗粒能够被迅速提升至分级室,同时选粉机自身的压阻也相对较小,细粉在选粉机内的停留时间较短,选粉机具有最高的分级效率.试验结果和工程应用表明,导流圈的设计有效提升了立磨选粉机的性能和产量.

In order to improve the velocity of airflow into grading room,a diversion circle is designed in vertical mill modification.The RNG k—ε turbulent model and DPM model are applied to carry out air-solid two-phase numerical simulation in the vertical mill classifier.The contour of gas-phase velocity,pressure and the particle trajectory are compared and analyzed as the angle α of diversion circle varies.Simulation results show that the velocity of airflow is limited under large value of α,while the pressure drop of classifier increases under small value of α.It is also shown that the classifier has the highest efficiency when α equals 60° because then the pressure drop of classifier is small and the residence time of fine powder is the shortest.The experiment and application indicate that the design of diversion circle improves the efficiency and productivity of the vertical mill classifier.