With focus on investigating the effect of combustor scale on the conversion of fuel-N to NO

x

and N

2

O

experiments are carried out in three combustors

including single coal particle combustion test rig

laboratory scale circulating fluidized-bed boiler (CFB) and full scale CFB in this work. For single coal particle combustion

the majority of fuel-N (65%-82%) is released as NO

x

while only a little (less than 8%) fuel-N yields N

2

O. But in laboratory scale CFB

the conversion of fuel-N to N

2

O is increases

but the conversion of fuel-N to NO

x

is quite less than that of single coal particle combustion. This is because much char in CFB can promote the NO

x

reduction by increasing N

2

O formation. In full scale CFB

both of the conversion of fuel-N to NO

x

and the conversion of fuel-N to N

2

O are smaller than laboratory scale CFB.