插杆式塞棒去除水口处夹杂物的机理与方法研究

Due to the inclusion in the process of continuous casting, nozzle in tundish often appear phenomenon of clogging which lead to molten steel drift and mold level fluctuation anomaly. When it is serious, the nozzle will be blocked and the cast should be stopped and the inclusion was bad directly for steel quality. The mechanism of adsorption inclusion by stopper with adsorption rod was researched. The thermodynamic model of inclusion reaction adsorption was established, and the impurity removal rate was calculated with different materials such as calcium base, magnesium base and so on for adsorption rod. Fluent software was used to carry out numerical simulation, liquid steel and inclusion flow in the nozzle were affected by the factors such as liquid steel flow rate, nozzle size, time of putting rod and insert amount, and the dynamics conditions of adsorption reaction in the nozzle process was determined. The water model experiments were carried out to draw reaction adsorption kinetics curve. The structures of stopper and adsorption rod were optimized and the effects of adsorption inclusion were analyzed on different structures such as pipe, concave holes, grooves, salient point and rib. The high temperature tundish simulation platform was constructed and the hot experiments of removing inclusion in nozzle by stopper with adsorption rod were done to determine appropriate parameters and increase impurity removal rate above 80%. The project reserched the foundational thermodynamics and knetics of adsorping inclusion, and exploit the technology of removing inclusion in nozzle by stopper with adsorption rod. It can improve steel cleanliness and ameliorate clogging problem. It set down a foundation of theory and practice for producing high quality clean steel with high efficiency and low cost.

连铸过程中由于夹杂物的原因，中间包水口常出现结瘤现象，导致钢水偏流，结晶器液面波动异常，严重时可能出现水口堵塞、断浇；进入结晶器的夹杂物直接影响钢的品质。课题通过研究插杆式塞棒吸附夹杂物的作用机理，建立夹杂物反应吸附热力学模型，计算钙基、镁基等不同材质吸附杆的除杂率；利用Fluent软件开展数值模拟，研究钢液流速、水口尺寸、插杆时间、插入量等因素对水口内钢液和夹杂物流动的影响，确定水口内反应吸附过程的动力学条件，并开展水模实验，绘制反应动力学吸附曲线；优化塞棒和吸附杆结构，重点分析通管、凹孔、凹槽、凸点、凸棱等杆体结构吸附效果；建设高温中间包模拟平台，开展吸附杆去除水口夹杂的热态实验，确定合适的插杆参数，提高水口除杂率。通过对夹杂物反应吸附的热力学和动力学基础研究，开发插杆式塞棒去除水口处夹杂物的新技术，提高钢水洁净度，解决水口结瘤问题，为低成本高效率生产洁净钢奠定理论和实践基础。

铸坯质量受钢水中夹杂物影响较大，现有连铸工艺中浸入式水口做为保护浇注的连接通道，其内钢液流速高，夹杂物激烈碰撞水口壁，存在去除夹杂物的优势。针对钢液中夹杂物的吸附行为，围绕夹杂物、钢液、吸附杆之间的作用机理，开展了理论与实验研究。.建立了单个夹杂物与吸附杆的吸附数学模型，研究表明Al2O3的临界停留速度大于1 cm•s-1，临界剪力大于1N•m-2，TiO2的临界停留速度大于4 cm•s-1，临界剪力大于10 N•m-2，TiO2比Al2O3更容易吸附，反应生成的MgAl2O4使半径小于42μm的夹杂物吸附在壁面上；钢液湍流漩涡中0~23μm夹杂物跃迁轨迹呈螺旋锥形；湍流碰撞引起的夹杂物之间聚合能力和碰撞长大速率高于布朗碰撞、斯托克斯碰撞；“钢液-凝聚态夹杂-耐材”间的粘附力数量级为10-4，与钢液表面张力成正比。.采用Fluent数理模拟研究，不同杆体半径下凹槽部位容易产生涡漩，矩形凹槽上部是夹杂物聚集吸附的高概率区，比圆形凹槽和钩型凹槽的影响强烈，矩型凹槽4×4×10mm有明显较大的漩涡，凹槽数目越多且凹槽交错分布方式吸附率最高。.水模拟实验平台上研究表明，夹杂物在矩型凹槽上部聚集，在钩型凹槽下部聚集，矩型和钩型形凹槽内部存在明显漩涡，矩型凹槽内部流场对主流区的影响能力为35%，钩型形凹槽16×4mm，α=45°对主流区影响为48%，传质能力强；矩型凹槽4×4×20mm内夹杂物碰撞的最小次数在左壁面为7.5次/s•mm2，后壁面为4次/s•mm2。.建立了实验室高温热态实验平台，研究表明凹槽深度、方向和吸附面对于钢液中夹杂物的吸附影响较大，最佳凹槽深度为2~3mm，凹槽垂直旋转方向时吸附层最大厚度为362.9μm，平行旋转方向时为404.3μm，随着凹槽吸附面变大， >1μm的夹杂物最大减少倍数在0.75倍以上。多因素影响下，<5μm和10~20μm的夹杂物，在凹槽个数为3，深度为2mm，平行于旋转方向且位于试样中部时去除效果最佳，而5~10μm和>20μm的夹杂物，在凹槽个数为3，深度为2mm，平行于旋转方向且位于试样边部时去除效果最佳。.通过插入水口的吸附杆吸附夹杂物，开发了插杆式塞棒去除水口处夹杂物的新技术，进一步提高钢水进结晶器之前的洁净度，同时减少水口结瘤，为低成本高效率生产洁净钢奠定了理论和实践基础。