Numerical study on staged combustion technology in burner of gas-fired boiler

A new staged combustion technology was proposed for reducing NOx emission of gas-fired boiler. A secondary air sleeve was installed outside the combustion head of the burner, and spiral blades were arranged in the sleeve to improve the flame combustion state of the burner. The accuracy of the numerical study was verified by comparing with the existing experimental results. The orthogonal test method, single factor analysis method and response surface method were used to study the influence of secondary air parameters (screw pitch, number of spiral blades, and primary air coefficient) on NOx emission. Results of single factor analysis shows that NOx emissions decrease with the decrease of screw pitch and primary air coefficient. Results of multivariate analysis shows that screw pitch and primary air coefficient had significant influence on NOx emission. The influence order of three factors on NOx emission is: screw pitch > primary air coefficient > number of spiral blades. The optimization results show that NOx emission is 18.95 ppm under the optimum conditions of screw pitch of 300 mm, number of spiral blades of 8, and primary air coefficient of 0.7. The numerical results show that the new air staged combustion technology can effectively reduce NOx emission of gas-fired boiler.