Study on heat transfer characteristics of air-cooled dry bottom ash removal system

Abstract

This paper develops a numerical model to describe the bottom ash cooling process based on an actual power plant. By means of computational fluid dynamics, the influence of adjusting the operating parameters of the dry bottom ash removal system was investigated. The heat exchange enhancement effect and the resulting consequences were comprehensively considered. After comparing its results with the measured values, the model is considered valid. The numerical results indicate that: increasing air volume is an effective method to reduce ash discharge temperature but not desirable; the ash discharge temperature decreased from 452.47 K to 446.27 K, but the air outlet temperature also decreased by 6.05 K. Increasing the running speed of the conveyor belt is an ideal measure; the heat recovery coefficient improves by 7.53% as the speed increases from 0.046 m/s to 0.0766 m/s. In addition, a dry bottom ash removal system with a specific structure has rated ash handling capacity; its design should fully consider the amount of bottom ash discharge. Adjusting the operating mode may not significantly reduce the ash discharge temperature without other losses. The results provide a reference for designing and adjusting subsequent bottom ash sensible heat utilization equipment.