As a carbon-free fuel

ammonia is one of the high-quality alternatives to coal. However

its high ignition temperature and low laminar flame velocity pose significant challenges for ignition systems. To enhance the combustion characteristics of ammonia-coal cofiring

this study proposes an ammonia-coal hybrid burner with preheating capability and investigates its preheating combustion performance under different ammonia blending ratios and injection configurations through numerical simulations. The results show that the burner can form a stable preheating zone in the middle and rear parts under the condition of 0~50% ammonia blending

with a core temperature above 1 200 K. The preheating performance of the burner under different ammonia blending ratios is significantly higher than that under pure coal conditions. In 10%~50% ammonia-blended conditions

the burner outlet temperature increases by 1.3%~41.4% (10~315℃) and the enthalpy increase grows by 4.7%~15.1% (130~420 kJ/s) relative to pure coal conditions. Through fuel pyrolysis and combustion within the burner

partial fuel nitrogen is released and completely converted into nitrogen gas. The fuel nitrogen fixation rate in 10%~50% ammonia-blended conditions shows 1%~28% improvement over pure coal combustion

which is expected to reduce NOx emissions at the furnace outlet.