Effects of structural parameters of a novel burner scheme with annularly combined multiple airflows on performance of a 660 MW tangentially fired boiler

Based on a previously validated 660 MW tangentially-fired boiler model, effects of equivalent ring diameter (ERD) and ring centroid offset distance (RCOD) of the proposed burner with annularly combined multiple airflows (ACMA) on boiler performance are investigated. Results show that both ERD and RCOD have great influences on ACMA boiler performance. Small ERD enhances the mutual entrainments of combined airflows, but the interweave of combined airflows hinders flue gas to get into their interior. Although large ERD weakens airflows’ mutual entrainments, flue gas can enter the interior of combined airflows to avoid the large pressure difference from the fireside to the backfire sides, so airflow deflection is alleviated. For coal combustion process, small ERD only promotes the intense combustion inside each ACMA burner, while increased ERD makes the intense coal combustion process more continuous at the burner gaps. The increased RCOD adversely affects both the aerodynamics and coal combustion performance, resulting in large airflow deflections and deteriorated coal combustion process. For the investigated boiler, ERD of 3.6 m and RCOD of 5.0 m are recommended. These findings deepen the understanding of ACMA burners and, together with future experimental research results, can provide guidance for its application in practical boilers.