Combustion characteristics of a swirl low-nitrogen burner with multiple gas injection pipes

A three-dimensional model for a burner is established, and effects of gas nozzle structural parameters on the combustion performance of the burner are studied. With a change in parameters, the reverse flow zone in the furnace changes obviously. The interaction and symmetry of the four reverse zones directly affect the flame stability. The change in the maximum and average temperatures in the furnace is not the main reason for the increase in NO$_x$ emissions at the furnace outlet ($M_{\mathrm{NO}}$). Most probably, the increase in $M_{\mathrm{NO}}$ is caused by the characteristics of the high-temperature area. In ten cases studied, the NO$_x$ emissions are all lower than 30 mg/m$^3$ and even lower than 10 mg/m$^3$ in some cases (under normal conditions), which indicates that the ultra-low nitrogen emission of the boiler can be achieved by reasonably modifying the nozzle structure.