循环流化床燃煤过程NO、N2O和SO2的排放行为研究

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.