Influence of Fuel on the Emission of Nitrogen Oxides (NO and N2O) from and 8-MW Fluidized bed Boiler

Artikel i vetenskaplig tidskrift, 1991

Emissions of nitric oxide (NO) and nitrous oxide (N20) from an 8-MW circulating fluidized bed boiler have been measured. The influence of the volatile content of the fuel was investigated by using three different fuels and operating the boiler at different bed temperatures, primary air stoichiometries, and excess air ratios. The measurements show that the emissions of NO are extremely low and dependent upon the char loading of the boiler as well as on the existence of unburned combustible matter such as CO and H2 in the gas phase. The char content and CO levels are influenced by the fuel, the bed temperature, and the air-to-fuel ratio in the combustion chamber. The levels of N20 emission are high and caused by the low temperatures used in fluidized beds. The N20 emission is influenced by bed temperature and oxygen concentration as well, but the influence of bed temperature is opposite compared to the dependence of bed temperature on the NO emission.