Study of combustion characteristics of hydrogen-doped natural gas in industrial boilers

In this paper, the characteristics of hydrogen-doped natural gas combustion in industrial boilers were investigated by means of numerical simulations. Initially, a jet flame test bench was constructed to conduct singlevariable experiments at various hydrogen doping ratios and excess air coefficients, thus analyzing the impact on flame combustion patterns. Computational Fluid Dynamics (CFD) numerical simulations were performed using the Fluent software, focusing on the combustion zones within the burner and boiler chamber. Simulations were based on actual operating conditions to set parameters, employing the k-epsilon turbulence model. The SIMPLE algorithm facilitated examination of the effect of hydrogen doping ratios on the combustion temperature and concentration of pollutants, with a particular focus on the concentration of the flow field, temperature field, NOx generation rate, and the concentrations of O2 and CO. The results show that: As the hydrogen doping percentage increases, the fuel flame propagation speed also increases, leading to a faster combustion process that yields a shorter, wider flame. Conversely, as the excess air coefficient rises, the flame becomes narrower, transitioning from a clearly-layered structure to a uniform one. Furthermore, an increase in the hydrogen doping ratio results in higher combustion temperatures and accelerated combustion reaction rates, accompanied by a decrease in CO concentration and an increase in NOx emission concentration. These results indicate that hydrogen doping enhances the combustion reaction and reduces pollutant emissions from gas combustion. This study provides a theoretical foundation for the practical application of hydrogen-doped natural gas in industrial boilers.