An optimized combustion chamber in gas wall-hung boilers for methane and hydrogen blending combustion

Aiming at carbon neutrality and reducing combustion production of pollutants in gas wall-hung boilers as well as improving combustion performance, a physical model of combustion chamber was established and numerical simulation of the combustion process was conducted. The results for the conventional-used Plane Orifice Plate show that the methane concentration at the bottom of the combustion chamber is high, leading to excessive flame aggregation and a large high-temperature zone. Considering the generation of both NO and CO, an optimization strategy for the burner was proposed and the numerical results show that compared with the conventional Plane Orifice Plate, the proposed Inclined High-Low Staggered Orifice Plate reduces both NO and CO emissions by 15.3 % and 75.7 %, respectively. The performance of the optimized structure was then validated through combustion experiments. Moreover, the present optimization strategy in hydrogen blending combustion was further examined. Though adding hydrogen causes higher temperature and NO generation, compared with the conventional one, the present optimal structure can reduce the NO mole fraction by around 60 % based on numerical simulation. The proposed novel burner structure demonstrates great potential in reducing pollutant and carbon emissions of civil gas appliances.