METHOD FOR NOX REDUCTION IN A CIRCULATING FLUIDIZED BED BOILER, A CIRCULATING FLUIDIZED BED BOILER AND USE THEREOF

摘要

The current invention relates to a method for reducing NOx emissions in a circulating fluidized bed boiler (CFB boiler), the CFB boiler comprising a fur- nace, the furnace comprising a bottomand fluidizable bed material. The method com- prises feeding primary air from below through the bottom and the bed material into the furnace for fluidizing the bed material and entrapping at least a part of the bed material for circulating it in the furnace; feeding secondary air into the furnace at a height above the primary air feeding, for sub-stoichiometric com- bustion of fuel; and feeding fuel into the furnace at a height above the primary air feeding for combusting the fuel. The method is characterized in comprising feeding over-fire air (OFA) into the fur- nace at a height above the secondary air feeding, for super-stoichiometric combus- tion of the fuel.