Research on a novel universal low–load stable combustion technology

Abstract

Current swirl combustion technology with faulty coal lacks flexibility for peak shaving without aids, necessitating a novel low–load stable combustion technology. This paper presented such a technology, developed from gas–particle experiments, that did not require major modifications to the burner secondary air structure. The new technology was applied to a low NOx axial swirl burner (LNASB) in a 350 MW boiler and a vortex swirl burner (VSB) in a 700 MW boiler. Comparative analysis at 20 % boiler load showed both prototypes lacked recirculation zones, characterized by high primary air axial velocities and low turbulence intensity. After modification, LNASB became stable combustion LNASB (SLNSB), and VSB became stable combustion VSB (SVSB). SLNASB had a central recirculation zone, while SVSB had a large annular recirculation zone. The relative length and diameter of SLNASB's recirculation zone were 0.7 and 0.472, while for SVSB, they were 1.5 and 0.477. LNASB had a diffusion angle of 4.7° and a swirl number of 0.511; SLNASB had 29.7° and 0.695; VSB had 11.4° and 0.445; SVSB had 33.3° and 0.784. The turbulence intensity of SLNASB and SVSB were notably higher than their prototypes. High–concentration particles accumulated at the center of SLNASB and SVSB, then entered the recirculation zone.