Ammonia is attracting attention as an energy carrier that emit no CO2 during combustion. However, ammonia emits a large amount of NOx. Previous studies have shown that thermal and fuel NOx are reduced by two-stage combustion, but the mechanism is far from clear. In this study, three dimensional numerical study were performed for a 10 kW class test furnace with methane and ammonia/methane as fuel for which gas sampling were performed. The result showed that the behavior that NO decreased by specific GER was observed when two-stage combustion was performed. It was also found that specific GER area was expanded by two-stage combustion.
