Study on the NOx formation of propane/ammonia co-combustion with a swirl burner

•NOx formation characteristics of NH3/C3H8 co-combustion were experimental studied.•The influence of primary air ratio for a swirl burner on NOx formation was explored.•Effects of ammonia doping ratio on NOx formation was discussed. Replacing traditional fuels with carbon free fuel ammonia is one of the important ways to achieve low carbon emissions. However, the problem of high concentration NOx formation in the process of ammonia combustion is still a topic of great concern. In this paper, the combustion experimental system was built to study the NOx generation characteristics of ammonia propane combustion for a swirl burner. The experimental results show that the addition of ammonia into propane flame greatly increases the amount of NOx, and reasonable organization of ammonia doping ratio and primary air ratio can effectively control the generation of NOx. When the ammonia doping ratio is less than 15%, the highest NOx appeared with the primary air ratio of 20%. When the ammonia ratio was greater than 15%, the increase of the primary air ratio had no obvious effect on the formation of NOx near the swirl burner. The flame temperature changes with the ammonia doping ratio, and when the ammonia doping ratio is 15%, the furnace gas temperature is the highest at each point along the furnace height.