磨煤机入口一次风混流及均流装置的设计

Design of primary air flow mixing and equalizing device for coal mill inlet

为了提高燃煤电厂磨煤机入口一次风量测量的准确性,采用CFD数值模拟方法设计了一套适用于紧凑型磨煤机入口一次风道的冷热风混流及均流装置,并通过数值模拟分析了中速磨煤机入口一次风道优化改造前后不同参考截面的速度和温度分布均匀性。结果表明:通过特殊设计的混合整流器、导流板和矩形栅格的组合布置,能够很好地满足风量测量元件对测量截面处流场和温度场均匀性的要求,从而使磨煤机入口一次风量测量的准确性和稳定性得到大幅度提高。

In order to improve the accuracy of the measurement of inlet primary air flow in a primary air duct,a cold-hot air flow mixing and equalizing device which is suitable for the primary air duct in front of the compact coal mill is designed by CFD numerical simulation,and the uniformity of velocity and temperature distribution in different cross-sections are analyzed by numerical simulation before and after the optimization and retrofit of the primary air duct at the medium speed coal mill inlet.Results indicate that the combined layout of the mixed rectifier,deflector and rectangle gridiron rectifier can well satisfy the requirements of the air flow measurement element in the uniformity of the flow field and temperature field at the measuring section.Therefore,the accuracy and stability of the primary air flow measurement of the coal mill inlet are greatly improved.