NUMERICAL STUDY ON THE CO-INJECTION CHARACTERISTICS OF COAL AND AMMONIA IN A SWIRL BURNER

Abstract

Co-firing NH₃ with coal is a promising solution for reducing CO₂ emissions, although it remains relatively new technology in Vietnam. This study employs CFD simulation using STAR-CCM+ software to perform the spray characteristics and NH₃ concentration distribution in a swirl burner, with a co-firing ratio of 10% NH₃, based on thermal input. The ammonia injection tube length was adjusted at five positions of 0 m, 0.4 m, 0.8 m, 1.0 m, and 1.2 m. Results show that the injector position significantly affects flow behaviors and NH₃ concentration. At 0.8 m, a central recirculation zone (CRZ) begins to form with a swirl number of 0.277. At 1.0 m, the CRZ becomes stable, and the lowest NH₃ concentration (0.3165 m³) is observed, indicating favorable conditions for stable combustion. Increasing the injector length reduces the volume of high NH₃ concentration regions, thereby improving combustion efficiency and limiting NH₃ presence in high-oxygen zones. These findings provide valuable technical insights for the design and operation of burners in coal–ammonia co-firing systems.