循环流化床燃煤过程NO、N2O和SO2的排放行为研究

在30kW循环流化床装置上进行了中国西部三种煤的燃烧实验，考查了燃烧温度、空气分级、空气过剩系数、固体颗粒循环料率和煤种等因素对NO、N2O、SO2污染物排放的影响。结果表明，强化空气分级可显著降低高挥发分煤种NO的生成量，但对N2O影响不大；增加空气过剩系数同时增加了NO与N2O的排放；增加固体循环料率显著降低NO生成量，但N2O排放略有增加；高阶煤燃烧生成较多N2O，低阶煤生成较多NO。燃烧温度1120K、过剩空气系数1.25下约85%燃料中N转化为N。实验范围内改变操作参数不影响SO2与CO排放量。

Behavior of NO, N2O and SO2 emissions during coal combustion in a circulating fluidized bed combustor

Emissions of NO, N2O and SO2 during coal combustion in a 30kW scale circulating fluidized bed (CFB) combustor were experimentally investigated. Three kinds of coals from western China were tested. The CFB combustor consists of a riser and a downer. The riser was designed as the coal combustor and the downer was used for the solid material circulation. The influence of combustion temperature, excess air number, air staging and coal rank on the emissions of NO, N2O and SO2 were studied and discussed. The experimental results show that increasing the combustion temperature can result in an increase of NO and a decrease of N2O in the flue gas. Air staging can decrease the NO emission significantly, but no obvious changing of N2O emission is found during the combustion of coal with high volatile content. Increasing the excess air number can lead to an increase of NO and N2O emission. A large decrease of NO emission and a slight increase of N2O emission can be observed when increasing the char concentration in the riser. About 85% percent of fuel N is converted to N2 for the combustion tests performed at 1120K and with the excess air number of 1.25. However, no obvious variation is observed for SO2 and CO emission with changing the CFB operation parameters, such as excess air and air staging.