Experimental and Numerical Simulation Research on Flow, Combustion and NO x Formation of a New Swirling Arch-Fired Boiler

Abstract

ABSTRACT Taking a 300-MWe arch-fired boiler as the research object, compared with original Babcock & Wilcox (B&W) combustion technology, the flow, combustion and NO x emission characteristics are comprehensively revealed under the novel biased-swirl-secondary-air combustion (BSSAC) technology with the help of cold-modeling experiments and numerical simulations. The results show that, for BSSA combustion technology, the dimensionless downward depth of the air flow from furnace arches is increased by 0.13, and the air flow fullness of whole the lower furnace is improved under the effect of burner secondary air near the water-cooled wall, vent air and staged air being injected step by step. The high-temperature reflux zone and gas reflux velocity under the furnace arch increase significantly, the ignition of primary pulverized coal air flow is advanced, and the combustion path of pulverized coal particles increases. The combustible content of fly ash decreases by 32.4%. At the same time, the ignition process of pulverized coal air flow near the center of the furnace is in a strong reducing and low oxygen atmosphere, and the multi-stage effective air supply is obtained in the downward process of pulverized coal combustion. The NO x emission concentration at the furnace outlet is reduced from 824 to 694 mg/m3 (O2 = 6%).