气淬高温熔渣颗粒运动和换热特性的数值分析

Numerical analysis on dynamics and heat transfer progress of a granulated molten slag particle by gas

建立了高炉渣颗粒运动与换热过程的数学模型,利用FORTRAN语言编写程序,通过四阶Runge-Kutta方法求解其动力学和传热方程,计算时充分考虑熔渣与冷却空气主要热物性参数随温度的变化,采用温度回升法计算熔渣凝固过程释放的潜热,提出在气淬空气中添加喷雾强化熔渣冷却,考察了渣粒尺寸对换热过程的影响。结果表明,飞行过程中渣粒速度受气淬空气影响先增大后减小;温度降低趋势随运动距离增加而减小,主要受对流换热系数影响,凝固过程持续时间较短;喷雾使渣粒在飞行过程中整体冷却速率明显升高,最终温度明显降低,而对熔渣的运动影响较小;相同初始工况下,熔渣粒径越小,运动越易受流场影响,渣粒整体冷却速率较高,换热效果越好。

In order to investigate the dynamics and heat transfer progress and characteristics of granulated molten blast furnace slag by blast air, a mathematical model was established and solved through the fourth order Runge-Kutta algorithm, the calculation program was compiled by FORTRAN. Considering that the efficiency of air cooling was low, a method of spray cooling was presented to improve the cooling rate. And the effects of varied particle size on movement and cooling were also researched. The variations of main thermal physical properties of slag and air with temperature were taken into account during the calculation progress that in order to enhance reliability of the study. And the temperature recovery method was usedto deal with the solidification of molten slag. The results indicated that the motion trail of the slag particle wasparabolic curve after granulation, and velocity of the slag particle was firstly increased and then decreased by theinfluence of quenching gas during the flight, the cooling rate of slag particle was mainly influenced by the convectiveheat transfer coefficient which varied with the relative velocity of blast air and slag particle. Meanwhile, the coolingrate of slag particle was significantly improved due to the addition of spray because of the evaporation of droplet andenhancement of convective heat transfer. The final temperature of the slag particle reduced with the decreasingparticle size, which meaned that the smaller particle size can make better cooling effect. And the motion parametersof the particle which had smaller size was more susceptible to the blast air. Generally, the smaller size of slag particle,the better of blast air cooling, and the smaller the space needed for granulation.