【摘要】 为降低低负荷下煤粉锅炉二次风系统风机耗电率、减少随二次风进入炉膛的飞灰对喷嘴附近水冷壁的磨损，以350 MW超临界四角切圆燃烧煤粉锅炉二次风系统为研究对象，采用数值模拟方法计算并分析了气体和飞灰流动特性，在此基础上对二次风系统结构进行优化。计算结果表明，原始结构时，同一角沿高度各燃烧器喷嘴的二次风量分配与配风方式有关，同一层4个角的风量分配基本相同；飞灰进入大风箱后，易在底部沉积，AA层辅助风速度最高、携带的飞灰浓度最大。结构优化后，可有效消除总风管内二次风的旋转趋势，减弱大风箱底部的气流旋涡，使进入各燃烧器喷嘴的飞灰浓度更均匀，降低喷嘴附近水冷壁的磨损风险。结构优化前后，二次风系统进出口压差最大可降低89.5 Pa。更多还原

【Abstract】 It is necessary to reduce the power consumption of the fan in the secondary air system of pulverized coal boiler under low load and reduce the wear of the water-cooled wall near the nozzles caused by the fly ash entering the furnace with the secondary air. The flow characteristics of gas and fly ash in the secondary air system of 350 MW supercritical tangential combustion pulverized coal boiler were calculated and analyzed by numerical simulation, and the structure of the secondary air system was optimized. The results show that the secondary air distribution of each burner nozzle along the same corner height is related to the air distribution mode, and the air distribution at the four corners of the same layer is basically the same. After the fly ash enters the big bellow, it is easy to deposit at the bottom. The AA layer has the highest auxiliary wind speed and the highest fly ash concentration. After the optimization of the structure of the secondary air system, the rotation trend of the secondary air in the main air duct can be effectively eliminated, the airflow vortex at the bottom of the big bellow can be reduced, the concentration of fly ash entering the nozzle of each burner is more uniform, and the wear risk of the water-cooled wall near the nozzle can be reduced. Before and after structural optimization, the maximum pressure difference between the inlet and outlet of the secondary air system can be reduced by 89.5 Pa.更多还原