电弧炉炼钢熔池内氧气-石灰粉混合喷吹动力学特性研究

Because of the raw material composition and furnace structure of the electric arc furnace, the velocity of molten bath is slow, temperature distribution is uneven, the fluctuation of impurity element content is large, and thermodynamic condition of dephosphorization is bad, which is inimical for steelmaking in a highly efficient and low-cost method. The oxygen and lime-powder compound jet under the molten bath of the EAF technology has been developed for electric arc furnace steelmaking process in recent years. The key to this technology is that the oxygen is used as a carrier gas to inject the lime-powder into the molten bath, which improves the mixing effect and dephosphorization rate of the molten bath by the reaction system of multiphase flow. The theoretical arithmetic, numerical simulations and water experiments would be adopted, and a three-dimensional multiphase flow model of “gas-solid-slag-steel” will be established in this research topic. With the help of the trajectory of particle capturing method, phase-interface tracking and 3D real-time velocity measurement, the experimental data could be collected. To provide theoretical basis and data support for the system design and unit operation of the oxygen and lime-powder compound jet under the molten bath of the EAF technology，this research would analyze the powder diffusion pattern in various phases at molten state, present the effect of injection parameter of the oxygen and lime-powder compound jet on the molten bath flow field, and correct the conventional theoretical formula.

受电弧炉炼钢原料成分与炉型结构限制，熔池流动速度慢、温度分布不均、杂质元素含量波动较大，脱磷反应动力学条件差，不利于实现电弧炉快速低成本冶炼高品质特殊钢。电弧炉炼钢熔池内氧气-石灰粉混合喷吹工艺是近年开发的满足电弧炉高效炼钢的喷射技术，即采用氧气将石灰粉直接喷入炼钢熔池内，依靠熔池内部“气-粉-渣-金”多相反应体系，实现熔池的高效混匀与快速脱磷。本课题采用理论计算、数值模拟和水力学模拟研究方法，结合粒子轨迹捕捉、界面实时跟踪及三维动态测速等手段，建立电弧炉三维等尺寸“气-粉-渣-金”多相流耦合模拟架构，探明熔融介质环境中石灰粉在各相内部及相界面的扩散模式与迁移规律，确定熔池内部氧气-石灰粉混合流股喷吹参数对熔池流场分布特性的作用规律，修正传统理论计算公式，为电弧炉炼钢熔池内氧气-石灰粉混合喷吹工艺系统设计与单元操作提供理论依据和数据支撑。

电弧炉熔池内氧气-石灰粉喷吹技术具有加快炼钢冶炼节奏，提高终点钢水品质，减少过程原辅料消耗与降低渣层泡沫化严重等性能指标优势。但氧气-石灰粉混合喷吹参数设计缺乏理论依据，冶炼过程粉剂传质扩散效果不理想，导致氧气-石灰粉混合喷吹工艺未能充分发挥其冶炼效果。因此，开展了电弧炉炼钢熔池内氧气-石灰粉混合喷吹动力学特性研究。. 项目采用了数值模拟和水力学模拟的方法，明确了粉粒可有效强化气体射流的初始冲击动能，提高熔池内气体射流水平与竖直冲击深度。发现了射流垂直冲击深度随气-固喷吹元件角度增大而增大，但射流水平冲击深度随气-固喷吹元件角度增加呈先升高后下降的趋势，射流水平冲击深度对应气-固喷吹元件角度拐点为20°。基于流体力学理论计算，建立了熔池内气-固喷吹射流轴线轨迹方程，并与水力学模拟结果进行了交互印证。.开展了电弧炉熔池内氧气-石灰粉喷吹效能优化研究，发现了熔池内喷吹可显著强化熔池中下部区域的钢液运动速度，增强能量和物质传输效率。基于电弧炉“熔池内喷吹+炉壁侧吹”吹炼模式，围绕典型电弧炉炉型几何结构，提出了熔池内气-固喷吹元件与炉壁集束氧枪的最佳组合布置方式。研究结果表明，本项目研究范围内熔池混匀效果影响因素排布顺序为：喷吹流量>埋入深度>水平布置倾角>垂直布置倾角。. 利用50吨电弧炉开展了电弧炉熔池内氧气-石灰粉喷吹预工业试验，在熔池内仅喷吹氧氮混合气的条件下，工业结果表明炉渣FeO和TFe含量分别降低5.28%、4.63%；钢铁料和氧气消耗分别降低9.2kg/t、5.3Nm3/t；终点钢液磷含量降低3.8%；终点钢液碳氧积由0.00318降低至0.00252;冶炼周期缩短了2.9min，钢液终点质量和经济指标得到了明显改善. 本基金项目研究结果为电弧炉熔池内氧气-石灰粉混合喷吹工艺的高效稳定运行提供了基础实验数据和改进优化方法，为电弧炉熔池内喷粉技术的工业化推广与应用提供了理论依据与实践经验。