Evaluation of wide-range coal combustion performance of a novel down-fired combustion technology based on gas–solid two-phase flow characteristics

Abstract

In order to achieve peaking carbon dioxide emissions and carbon neutrality, a variety of down-fired combustion technologies has been proposed. The existing central air supplied combustion technology (CASCT) used for burning blended bituminous coal faces some serious problems. In order to solve the problem of the wide-range coal combustion in down-fired boiler, this study proposes a novel primary air biased combustion technology (PABCT). The coal gas–solid two-phase flow characteristics and numerical simulation of combustion characteristics under the PABCT and CASCT were compared. The results indicated that compared with the CASCT, under the PABCT, the velocity attenuation in the vertical direction is slower and the airflow diffusion range is smaller below the arch. The attenuation rate of particle volume flux with the downward flow of pulverized coal is slow, and the space utilization rate of the lower furnace is high under the PABCT. The thermal numerical simulation confirms the conclusion obtained from the cold gas–solid two-phase experiment. The PABCT exhibits the characteristics of large undershoot depth of coal/air flow, low temperature in the burner nozzle area, high burnout, low NOx emissions, and slag prevention, thus making it more suitable for wide-range coal combustion from the perspective of furnace flow and combustion.