高炉回旋区运动现象的数值模拟

风口回旋区是高炉内产生还原气体及热量的主要区域,颗粒相和气相在风口回旋区内的相互作用非常剧烈。回旋区的形状和大小决定了炉内煤气流的一次分布,是炉况顺行的基础。本文为了从颗粒尺度来描述回旋区内部气体和颗粒的运动行为,建立和发展了离散单元法和流体计算力学耦合模型。耦合模型考虑了多个相间力的作用(包括曳力、虚假质量力、升力和压力梯度力),得到了不同时刻风口前焦炭颗粒的分布图、体积分数云图、速度矢量图等。这些图表明在鼓风速度130 m/s时,风口前有颗粒被吹开,形成了明显的空腔,风口前及其附近区域的颗粒在做回旋运动,可以断定回旋区已经形成,且在6 s时风口回旋区达到稳定。

NUMERICAL SIMULATION OF RACEWAY PHENOMENA IN A BLAST FURNACE

The gas phase and particle phase interact very violently in blast furnace (BF)raceway which plays a very important role in ironmaking processes and is also the basis of smooth operation of the furnaces.For better describing the particle and gas behaviors in a raceway,a coupled simulation approach of discrete element method (DEM) and computational fluid dynamics (CFD) has been successfully developed to study the gas-solid flow in fluidization at a particle scale in this paper.In this work,the multiple particle-gas interaction forces (including drag force,virtual mass force,lift force and pressure gradient force) are considered.Then,the particles motion,particle phase volume fraction,velocity vector fields of particles,velocity vector fields of gas phase and scalar velocity contours of particles in front of tuyere are described by the coupled DEM-CFD model when the blowing velocicy is 130 m/s.The result shows a stable cavity is formed in front of the tuyere,and some particles make circular cyclotron motion in this cavity which can be defined as raceway.The particles motion of raceway achieves stability when the blowing time is 6 s.