NO_x Emissions From Combustion of High Sulfur Lignite in an ABFBC Test Rig

NO_x emissions from fluidized bed combustion of various coals have extensively been investigated and well documented. However, NO_x emissions from combustion of Turkish lignites with high ash, volatile matter and sulfur contents have not drawn much attention to date. Recent trend in utilization of indigenous lignites in fluidized bed boilers necessitated investigation of pollutant emissions and adaptation of fluidized bed combustion technology to these lignites. In this study, experimental results of various runs pertaining to the formation and emission of NO_x from METU 0.3 MW_t Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) test rig burning typical indigenous lignites; Aydin without limestone addition and Beypazari with and without limestone addition are presented. NO_x profiles along the combustor show that concentrations are higher in bed compared to those in freeboard and that conditions leading to higher unburned volatiles in freeboard enhances NO_x reduction in that region. Limestone addition results in higher concentrations of NO_x in bed but lower concentrations in freeboard, albeit insignificantly.