Study of combustion characteristics in the self-stabilized stage of a novel self-stabilized pulverized coal burner

This study proposes a novel, self-stabilized pulverized coal burner (SSCB) for deep peak shaving, enabling stable combustion without an external ignition source. The new burner structure incorporates a hot-air recirculation channel to enhance pulverized coal combustion and achieve self-stabilized combustion within the burner. As combustion originates from the burner self-stabilized zone (BSZ), its combustion characteristics across a wide load range were investigated numerically and verified by experiments. The pulverized coal-air stream velocity ( u 0 ) varied from 14-22 m/s, the pulverized coal concentration ( a ) ranged from 0.2-0.6 kg/kg, and the return hot air flow rate ( q ) spanned 60-150 Nm 3 /h. Results indicate that recirculation zone 1 (RZ1) near the return hot air nozzle is crucial for stable combustion, and q exerts the greatest influence on RZ1. The influence of u 0 , a , and q on the recirculation zone and combustion characteristics in the BSZ were discussed. A lower u 0 increases the combustion gas temperature and reduces the ignition distance ( l ). Optimal values of a and q balance stable combustion and anti-disturbance. Additionally, reducing u 0 and q supports the hypoxic preheating denitrification (HPD) of pulverized coal, reducing NO x emission concentration, with an optimal a for nitrogen reduction. The high and uniform combustion gas temperature at the BSZ outlet provides the necessary ignition heat for the downstream fuel, thereby enabling staged ignition and sustaining stable combustion. These findings provide valuable insights for advancing combustion stability during deep peak regulation and reducing NO x emissions from the source. Fig. 1 Schematic diagram of the stable combustion principle of BSZ.Fig. 2 Temperature distributions under Cases 1-3.