In order to reduce CO2 emission from coal-fired boiler, it is expected that ammonia is used as a fuel which has no carbon content. In that case, it is concerned that NOx concentration in flue gas increases because ammonia has more nitrogen content than coal. In this study, with 10 MWth test furnace, ammonia and pulverized coal co-firing test was conducted with ammonia velocity as a parameter at 20 % co-firing rate. The result shows that NOx concentration in flue gas of co-firing is as same as that of single coal combustion. In addition, co-firing test for evaluating effect of two-stage combustion ratio, heat input and fuel ratio on NOx was conducted. The results show that condition for reducing NOx concentration in ammonia co-firing is clarified.
