440 t/h CFB锅炉低氮改造试验研究

Experimental Study on Low Nitrogen Transformation of a 440 t/h CFB Boiler

针对某440 t/h循环硫化床(Circulating Fluidized Bed,CFB)锅炉存在NOx易超标问题,进行低氮改造,改造方案包括二次风分级优化、烟气再循环和选择性非催化还原(Selective Non-Catalytic Reduction,SNCR)提效等。改造后,有效降低NO_(x)最终排放,锅炉在26%锅炉最大连续蒸发量(Boiler Maximum Continuous Rating,BMCR)负荷及以上实现NOx排放低于50 mg/m^(3)。通过改造表明,烟气再循环有效保证低负荷流化均匀性,能有效调节炉内燃烧温度,同时提高二次风安全性和调节性,进而提高锅炉负荷响应速率和协调控制性。

Aiming at the problem that the NOx of a 440 t/h circulating fluidized bed(CFB)boiler was easy to exceed the standard,a low nitrogen transformation was carried out.The transformation scheme includes secondary air classification optimization,flue gas recirculation and selective non-catalytic reduction(SNCR)efficiency improvement.After the transformation,the final NOx emission was effectively reduced,and the NO_(x)emission of the boiler was lower than 50 mg/m^(3)at 26%boiler maximum continuous rating(BMCR)load and above.The retrofit shows that flue gas recirculation can effectively ensure the low load fluidization uniformity,effectively regulate the combustion temperature in the furnace,improve the safety and regulation of secondary air,and improve the boiler load response rate and coordination control.