气淬作用下熔渣粒化机理及破碎效果分析

Analysis of Slag Granulation Mechanism and Crushing Efficiency Under Gas Quenching

针对熔渣气淬粒化工艺,在实验的基础上开展了气淬作用下的熔渣粒化过程数值模拟.利用VOF模型追踪自由界面、Realizableκ-ε模型处理湍流流动.模拟得到了气淬熔渣粒化过程,并分析了熔渣破碎机理.进一步建立了无量纲数局部动量比,对熔渣的黏度及气渣局部动量比进行了影响因素分析.结果表明:熔渣存在两种破碎形式,一种为R-T不稳定性所产生的柱状破碎,主要由渣流迎风面和背风面存在的局部高压区所导致;另一种为K-H不稳定性主导的表面液膜破碎,其主要由气渣界面间的速度梯度所引起.熔渣黏度的增加会使熔渣的颗粒粒径增大,破碎效果降低;气渣局部动量比的增大增强了熔渣的表面液膜波动,使剥离的颗粒数量增多,破碎长度减小,熔渣破碎效果加强.

Aiming at the granulation of slag under gas quenching,the numerical simulations of the slag granulation process under gas quenching is carried out on the basis of experiments.The VOF model is used to track the free interface and the Realizableκ-εmodel is used to deal with the turbulent flow.The granulation process of gas-quenched slag is simulated and the mechanism of slag fragmentation is analyzed.The dimensionless local momentum ratio is then further established and the influence factors of slag viscosity and gas-slag local momentum ratio are analyzed.The results showed that there are two forms of slag fragmentation under gas quenching.One is the columnar fragmentation caused by R-T instability,mainly caused by local high pressure zones on the windward and leeward sides of the slag flow.The other is surface liquid film breakage dominated by K-H instability,which is mainly caused by the velocity gradient at the gas-slag interface.The increase of slag viscosity will increase the particle size of the slag and decrease the crushing efficiency.The increase of the local momentum ratio enhances the liquid film fluctuations on the surface of the molten slag,and thereby increase the number of stripped particles,reduce the fragmentation length,and enhance the fragmentation efficiency of the molten slag.