Research progress on ammonia-coal co-combustion technology

The ammonia-coal co-combustion technology aligns with China’s national energy conditions, where the main status of coal will not fundamentally change in the short term. This technology is crucial for China to achieve carbon emission reduction in the power system and meet the “carbon peaking and carbon neutrality objectives”. However, due to the distinct combustion characteristics of ammonia compared to traditional fossil fuels, blending ammonia fuel into coal-fired boilers may result in issues such as reduced combustion stability and elevated NO_x emissions. Based on relevant domestic and international research on ammonia-coal co-combustion, the existing problems of ammonia fuel are presented. The impacts of variables such as the ratio and injection location of ammonia, air distribution mode, and combustion temperature on the combustion and emission characteristics of ammonia-coal co-combustion are analyzed. Furthermore, changes in the reaction mechanism during ammonia-coal co-combustion are elucidated. The economic analysis of ammonia-coal co-combustion technology is also presented, along with future research and application prospects. The results indicate that under a 20%−40% ammonia blending ratio, the combustion and emission characteristics can meet energy conservation and emission reduction engineering requirements through proper fuel staging, air staging, and oxy-fuel combustion. Ammonia-coal co-firing results in a decrease in overall furnace temperature, negatively impacting on fuel burnout and the reduction of NO_x by ammonia and coal coke. Additionally, the H₂O-rich atmosphere created by ammonia doping could enhance the generation of NO_x. At a 20% ammonia co-firing ratio, boiler thermal efficiency remains essentially unchanged, while carbon emissions can be reduced by approximately 20%. Furthermore, advancements in green ammonia production technology could make the cost of co-combustion competitive with, or even more advantageous than pure coal combustion, further promoting the construction of China’s new energy-based new power system.