Predicition of Stable and Unstable Flows in Blast Furnace Raceway Using Numerical Simulation Methods for Gas and Particles
Predicition of Stable and Unstable Flows in Blast Furnace Raceway Using Numerical Simulation Methods for Gas and Particles
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DOI：
10.2355/isijinternational.45.1406
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发表时间：
2005
影响因子：
1.8
通讯作者：
S. Yuu;T. Umekage;Takafusa Miyahara
中科院分区：
文献类型：
--
作者：
S. Yuu;T. Umekage;Takafusa Miyahara
用离散单元法计算焦炭颗粒间的多体相互作用，用基于蒙特卡罗直接模拟的硬球模型计算粉末颗粒两体相互作用，用有限差分方法数值分析N-S方程，并引入气体与颗粒间的相互作用项，对实际高炉回旋区的颗粒和气体流动进行了数值模拟。在模拟中，我们考虑了软化熔化区的存在。计算结果表明了回旋区的形态及其随不同周期的波动。模拟结果还给出了焦炭、粉尘和气体的速度分布以及这些颗粒的堆积比分布。系统的动力学特性具有波动性和不稳定性。由于空气和颗粒的流动，在下部炉芯和风口下方的下壁区域形成了高填充的焦炭和粉末颗粒层，软化熔化区的存在和消失在软化区和回旋区附近形成了高风速区，软化熔化区的存在和消失在软化熔融区和高填充炉心区之间的层中出现了高风速区，在炉壁附近和回旋区产生了不稳定的高风速区。焦炭和粉末颗粒以及软化熔化区会在炉内产生不稳定状态，粉末颗粒在炉内循环扩散，由于颗粒的碰撞和团簇的断裂，形成环形的多层粉末颗粒团簇。计算结果表明，在高炉内出现了一个异常的现象，即由于软化熔融区的作用和小焦炭颗粒在炉心区域的堆积，形成了与炉壁接触的异常高风速宽区。
We have numerically simulated the particle and gas flows in the raceway region in an actual blast furnace of which dimension is the same as that of the commercial blast furnace using Distinct Element Method for the computation of the multi-body interaction among coke particles, Hard Sphere Model for two body interaction of powder particles based on Direct Simulation of Monte-Carlo Method and Finite Difference Method for the numerical analysis of Navier-Stokes equations with the interaction terms between gas and particles for the gas flows. In the simulations we have taken the existence of softening melting zones into account. The present calculation results indicate the raceway pattern, its fluctuations with various periods. The results also indicate the velocity distributions of coke, powder and gas, and packing ratio distributions of these particles. The dynamical characteristics fluctuate and are unstable. The highly packed coke and powder particle layers are formed in the lower core and in the lower wall regions under the tuyere due to the air and these particle flows.The high air velocity region appears in the layer between the softening melting zones and the highly packed furnace lower core region, and the unstable high air velocity region is produced near the furnace wall and on the raceway by the existence and the disappearance of softening melting zones. The coke and powder particles and the softening melting zones would yield the unstable state in the furnace.The powder particles circularly spread and make the circularly multi-layered powder particle clusters caused by the particle collisions and the breakage of clusters. Some of the powder particles flow upward and others are packed in the furnace lower core region by the particle and the air flows.Our calculated results present an unusual phenomenon example in the blast furnace, that is, the unusual high air velocity wide region touched to the furnace wall is formed due to the effect of the softening melting zones and the accumulation of small coke particles in the furnace center region.