Understanding of the flow field and heat transfer in a boiler is important to meet with the often-conflicting objectives of efficient steam generation, safe operation and minimization of pollutant emissions. Steam generation requires high gas temperatures, which often lead to high NOx emissions. High gas temperatures inside the boiler may also lead to slagging and fouling problems, which adversely affect the heat transfer to the steam side. One of the principal ways of finding a compromise in tangentially fired pulverized coal (PC) boilers, which constitute the majority of the utility boilers, is through tilting the burners. The current work seeks to obtain a detailed understanding of the effect of burner tilt on the flow and heat transfer inside the boiler by utilizing numerical simulations. Computational fluid dynamics (CFD) simulations were performed on a 210 MWe tangentially fired pulverized coal boiler to understand the impact of two vertical burner tilt angles, − 15° and + 15°. The effect of burner tilt was investigated by analyzing the effect on gas flow, temperature distribution, coal particle trajectories and NOx emissions. The results suggest that a downward tilt of the burner (− 15°) has a significant effect on the particle trajectories and the residence time of the particle in the high temperature burner zone. The temperature of the exit gas was reduced by 33 K due to the downward tilt. NOx emissions were reduced by about 5.5% when the burners were tilted downward by 15° which be attributed to two factors, namely the relatively insignificant contribution of thermal NOx mechanism in utility boilers and the role of NOx reburning in reducing conditions.

了解锅炉中的流场和传热对于实现高效蒸汽产生，安全运行和污染物排放量最小化这一经常相互冲突的目标非常重要。产生蒸汽需要较高的气体温度，这通常会导致较高的NOx排放量。锅炉内部较高的气体温度也可能导致结渣和结垢问题，这会对传至蒸汽侧的热量产生不利影响。在切向燃烧煤粉（PC）锅炉中寻求折衷的一种主要方法是倾斜燃烧器，而这些燃烧器构成了公用事业锅炉的绝大部分。当前的工作旨在通过数值模拟获得对燃烧器倾斜对锅炉内部流动和传热的影响的详细理解。在210 MWe切向燃烧的粉煤锅炉上进行了计算流体动力学（CFD）模拟，以了解两个垂直燃烧器倾斜角-15°和+ 15°的影响。通过分析对燃气流量，温度分布，煤颗粒轨迹和NOx排放的影响，研究了燃烧器倾斜的影响。结果表明，燃烧器的向下倾斜（− 15°）对颗粒轨迹和颗粒在高温燃烧器区域中的停留时间有重大影响。由于向下倾斜，出口气体的温度降低了33K。当燃烧器向下倾斜15°时，NOx排放减少了约5.5％，这归因于以下两个因素：