Effect of the Vane Angle for Outer Secondary Air on the Flow and Combustion Characteristics and NO_x Emissions of the Low-NO_x Axial-Swirl Coal Burner

Abstract

We conducted a cold air experiment and numerical simulation to investigate flow and combustion characteristics and NO _x emission of a low-NO_x axial-swirl burner in a 600 MWe bituminous coal-burning boiler. Comparison of single-phase numerical simulation results and measurements made by a probe with hot-film sensors shows that the numerical model is a reasonable description. By changing the vane angle for outer secondary air, we obtain different results for the recirculation zone, the divergence angle, the distance that the recirculation zone extends into the burner, the mass of the flue gas that returns to the burner, the temperature of the furnace, and the concentration of NO _x emission. The best vane angle for the outer secondary air is determined to be 15°.

This work was supported by the Hi-Tech Research and Development Program of China (contract no. 2007AA05Z301), and the Postdoctoral Foundation of Heilongjiang Province (LRB07–216).