大型电站烟风管道节能优化及工程应用

为探究大型火力发电厂烟风管道系统优化机理，利用数值模拟的方法，对所建方截面烟道和圆截面烟道模型的流场进行数值计算并分析。结果表明：方截面烟道的内撑杆后存在明显的尾迹涡流区，且流动稳定以后的直烟道有效流动面积仅为烟道截面总面积的79%左右；方截面直烟道和90°弯头的出口速度偏差分别为0.209、0.246，烟道压力损失严重；圆截面烟道内部流动分离相对减少，圆截面直烟道和90°弯头的出口速度偏差分别为0.052、0.146，与方截面烟道相比，压损减少60%以上。同时，通过对某300 MW电厂烟道改造项目的数值计算可知，经过将烟道截面优化为圆形和整体布置优化以后，烟道阻力下降了74.6%，内部流场均匀性得到改善，经济效益明显。

Optimization and Engineering Application toward Energy Saving for Flue Gas Ducts in Large Coal-Fired Power Plants

To explore the mechanism of flue gas duct optimization for large coal-fired power plants, by virtue of numerical simulation, the flow fields of a square and a circular cross-section flue gas duct model are calculated and analyzed respectively. The result indicates that, there exists an obvious tail flow eddy zone behind the inner supports in the square cross-section flue gas duct, and the effective flow area of the straight duct is merely 79% of the total cross-section area after the flow is stabilized. The outlet velocity deviation is 0.209 in the square straight duct and 0.246 in the square bend, which shows substantial pressure losses. However, the outlet velocity deviation of the circular flue gas duct is 0.052 in the straight duct and 0.146 in the bend, which means that the flow separation is alleviated in the circular cross-section flue gas duct. Moreover, compared with the square cross-section flue gas duct, the pressure losses are lowered down by more than 60 percent. The numerical calculation of the flue gas duct reconstruction project of a 300 MW power plant shows that after the replacement of original square flue gas ducts with the circular ones and the overall layout optimization, the flue resistance has been decreased by 74.6% and the evenness of the flow fields has been improved. Therefore, great economic benefits have been achieved through the reconstruction project.