Numerical Investigation on Phase Transformation Thermal Characteristics of High Temperature Slag Particle

After the molten slag was granulated by centrifugal granulation, it would fly in the granulation bin for a period of time. The slag particles exchanged heat with the cold air and water wall by convection and radiation was a typical multi-component unsteady phase-change thermal process. The study of heat characteristics of the air-cooled phase transition of slag particles has important guiding significance for the enhancement of the cooling rate and design of the granulation chamber. In the paper, the solidification-melting model coupled with the radiation heat transfer model method was used to investigate the effects of the temperature of air and water wall, the velocity of air, and diameter of slag particles on the cooling characteristics. The variable thermal conductivity, variable viscosity, variable density at different temperature range and the physical properties of the phase transition temperature zone were fully considered in the model. The results indicated that the solidification time of the particles decreased with the decrease of the temperature and of cooling air, the increase of the velocity of air, the reduction of the temperature of the water wall and the reduction of the diameter of slag particles. Moreover, the diameter of slag particles has the most significant influence, and the temperature of the water wall had the least impact. By adjusting the above influencing factors, the cooling rate of the slag particles can be accelerated to prevent them from sticking to the water wall.