Effects of the number of wall mounted burners on performance of a 660 MW tangentially fired lignite boiler with annularly combined multiple airflows

Abstract

In previous work, a novel burner arrangement scheme with annularly combined multiple airflows (ACMA) was proposed to improve tangentially fired boilers’ performance. Its superiority over conventional wall-tangentially fired boilers was previously confirmed. Based on this, this work futher explores the influences of the number of burners and air nozzles (NBAN) in each wall-mounted ACMA burner on the boiler performance through three cases with different NBANs. Parameters related to in-furnace aerodynamics, combustion and heat transfer processes, and NOx transformation are analyzed. Results reveal that NBAN significantly affects the in-furnace aerodynamics, combustion behavior and heat transfer characteristics. With NBAN increasing from 4 to 6, the more scattered airflows effectively reduce flue gas peak velocity, thus reducing flue gas swirling intensity and the actual tangent circle diameter. Meanwhile, combustion performance and heat transfer uniformity with six burners and air nozzles are improved. However, when NBAN increases to 8, the coal combustion deteriorates slightly and the heat transfer uniformity decreases. Thus, six burners and six air nozzles in each ACMA burner are ideal to obtain the most desirable overall boiler performance. These findings deepen the understanding of ACMA burner, which can guide its future application in utility boilers.