Effect of Operating Conditions on NO x and CO Emissions in a Pilot‐Scale Vortexing Fluidized‐Bed Combustor with Flue Gas Recirculation

In order to study the effect of flue gas recirculation (FGR) by primary air mixed with FGR or nitrogen on NO x emissions in a fixed total primary air flow rate, the bed temperature, stoichiometric oxygen ratio in the combustion chamber, and excess oxygen ratio were investigated in a pilot‐scale vortexing fluidized‐bed combustor (VFBC). As a result, the NO x emissions could effectively be decreased with FGR in the VFBC. The lower NO x emissions were attributed to the fact that the FGR allows NO x to enter the reactor again with the chance of being reduced and that the FGR contains more CO 2 to suppress NO x formation or promote NO x reduction through its conversion to CO by reaction with char.