Film fragmentation mode: The most suitable way for centrifugal granulation of large flow rate molten blast slag towards high-efficiency waste heat recovery for industrialization

Abstract

In molten slag centrifugal granulation heat recovery technology, the centrifugal granulation process is crucially important to realize efficient heat recovery as well as high-quality resource utilization. Facing the actual large-scale industrial application, the film fragmentation mode is likely to be the suitable operational mode for centrifugal granulation due to its ability to handle large discharged slag flow. However, the fragmentation phenomena and mechanism in film fragmentation mode are unclear since most of the existing experiments scale is too small to reach this mode. Here, the authentic molten slag is employed as the working fluid to investigate the centrifugal granulation characteristics in film fragmentation mode. A unique perforated disintegration of extended free slag sheet in film fragmentation mode is observed, and the good granulation performance is proved through the comparison with that in ligament fragmentation mode. The effects of operating conditions and structural parameters including granulator rotating speed, molten slag mass flow rate, initial slag temperature, rotary cup diameter, and granulation chamber radius are discussed on the particle size distribution and average particle diameter. Finally, the predictive correlation of granulation performance is put forward. For the industrial applications, the rotary cup diameter is recommended between 86 mm and 126 mm, and the granulation chamber radius should be set at least larger than 1.36 m if the granulator rotating speed is designed lower than 1800 rpm.