Numerical simulation of the influence of gear-type combustion stabilizer on the flow field distribution and combustion products of swirl burner

The gear-type combustion stabilizer (GCS) installed in the burner can effectively disturb the flow field. However, there is a lack of research on the impact of GCS's position on NOx production. This study aims to design the optimal GCS position to enable stable combustion of pulverized coal (PC) and reduce NOx emissions. In comparison to the prototype burner, the extension of the central air pipe (CAP) resulted in delayed mixing of the central air with the primary air, delayed ignition of the PC, and a 2.93% reduction in the burnout rate (BR). Furthermore, the installation of a GCS in the primary air pipe (PAP) reduced the cross-sectional area of the flow path, increased the flow velocity, and delayed the ignition. The GCS disturbed the axial velocity at radial positions less than 0.5 m and formed a backflow, which led to an increase in the BR. At the burner outlet of the burner equipped with an internal-external gear-type combustion stabilizer (IEGCS), the PC gas stream formed a significant rich/lean separation. The CO content generated by the external gear-type combustion stabilizer (EGCS) burner is the highest, which is beneficial to inhibiting the formation of NOx. As a result, the NOx production was reduced by 17.02% compared to the prototype burner.