In this paper, a 600 MWe Babcock & Wilcox boiler is selected as the research object. Numerical simulation and field experiments have been applied to this study under original and new combustion systems. The new approach mainly involves changing the operation mode of swirl burner, rearranging secondary air, and employing separated over-fire air. Numerical results showed that NO_x emissions and the unburned combustible in flue dust decrease with the arrangement of the swirl burner changing from co-rotating mode to counter-rotating one. Consequently, counter-rotating mode of adjacent burners was chosen as the optimized arrangement. The introduction of separated over-fire air resulted in a remarkably reduction of the NO_x emissions, which reduced from 1085 mg/m³ to 547 mg/m³. With increase of the distance between separated over-fire air and arch from 0.5 m to 3.0 m, NO_x emissions changed slightly and the unburned combustible in flue dust were not greatly affected. When the distance continued increase to 6.0 m, NOx generation was suppressed and boiler efficiency declined. Considering the economic efficiency and NOx emissions reduction, the optimal sofa position is 3.0 m above the arch. In situ measurement results are consistent with the modeling predictions This work provides a feasible and economic approach for Babcock & Wilcox down-fired boilers to achieve high efficiency and low pollutant emissions.

本文以600 MWe Babcock＆Wilcox锅炉为研究对象。数值模拟和现场实验已在原始和新的燃烧系统下应用到这项研究中。新方法主要涉及改变旋流燃烧器的运行模式，重新布置二次空气以及采用分离的过火空气。数值结果表明，随着旋流燃烧器的布置从同向旋转改为反向旋转，NO _x排放量和烟尘中未燃烧可燃物减少。因此，选择相邻燃烧器的反向旋转模式作为优化布置。引入分离过火灾空气导致显着减少的NO的_X排放量，这从1085减少毫克/米³至547mg / m ³。随着分开的过火空气与拱之间的距离从0.5 m增加到3.0 m，NO _x排放量发生了微小变化，烟尘中未燃烧的可燃物没有受到很大的影响。当距离继续增加到6.0 m时，NOx生成受到抑制，锅炉效率下降。考虑到经济效率和减少NOx排放，最佳沙发位置为拱形上方3.0 m。原位测量结果与建模预测一致。这项工作为Babcock＆Wilcox向下燃烧锅炉提供了一种可行且经济的方法，以实现高效率和低污染物排放。