Energy saving from furnace slag: An analysis of free-surface film flow characteristics of liquid slag on the rotary cup

Blast furnace (BF) slag is regarded as a high-grade waste heat resource. Dry centrifugal granulation technology became an important method for its low-energy consumption, recovering waste heat, etc. In this paper, the analytic formulas of liquid film thickness and the average radial velocity were obtained by micro-element force analysis. The influence of various factors on liquid film was analyzed by computational fluid dynamics (CFD)simulation. It was revealed that liquid film produced a slip when the cup diameter was 50 mm and the rotary speed was 1500 rpm. The critical rotary speed of the slip increased with an increase in the cup diameter. The liquid film thickness changed almost linearly with the inlet mass flow rate. With the amount of slag constant, the influence of the slag inlet conditions on the liquid film at the edge of the cup was negligible. The surface tension mainly affected the initial spreading process of the liquid film. With the increase of the cup edge inclination angle, liquid film thickness increased.