W火焰锅炉低氮燃烧控制机理研究

摘要

To solve high nitrogen oxide (NOx )emission problem occurred in Foster Wheeler down-fired boilers,the combustion characteristics and NOx formation properties in the furnace were analyzed.The low NOx combustion control mechanism applying the “inj ection-reflux and multipoint-multistage”mechanism was developed.On the basis of this mechanism,the low NOx combustion retrofitting was carried out on a 660 MW unit boiler applying the Foster Wheeler technique.The experimental results after retrofitting indi-cate that the NOx emissions can not be reduced significantly by simply adding OFA system in down-fired boilers.The secondary air should be shifted from the rear and front wall to the right place of arches to real-ize the"inj ection-reflux and multipoint-multistage"mechanism in the whole furnace.Thus the ideal NOx e-missions level (≤800 mg/m3 )can be reached.%针对F W技术 W火焰锅炉存在的 N Ox 排放量高的问题，分析了其炉内燃烧及 N Ox 生成特性，提出了引射回流、多点分级的低氮燃烧控制机理，并基于该控制机理对某台660 MW机组FW技术W火焰锅炉进行了低氮燃烧改造。改造后测试结果表明，对于W火焰锅炉，仅通过增设OFA系统，并不能使NOx 排放量大幅降低，应同时将拱下二次风移至拱上合适位置送入炉膛，在全炉膛实现引射回流、多点分级的低氮燃烧方式，可将N Ox 排放量降至理想水平。