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连铸机结晶器内钢液的流动状态严重影响连铸坯的质量,尤其在弯月面处,钢液与结晶器保护渣直接接触,结晶器内弯月面不稳定引起的卷渣,是导致产品产生缺陷的主要原因之一,如冷轧薄板的线状缺陷和厚板的表面缺陷。在结晶器润滑不均匀时,还会增加漏钢危险。弯月面液面波动主要是由于浸入式水口吐出孔钢液剧烈的湍流和瞬态行为引起的。最近,在一台连铸机上浇注不同钢种已成为全世界钢铁生产商努力的一个主要方向。为了满足所有钢种的质量要求,对每个钢种都要求一定的浇注速度。对常规的浸入式水口而言,确保结晶器内有利的流动条件是一个难题。因此,比以往更需要一种新型浸入式水口,通过保持最佳的结晶器内钢液流动状态,以各种浇注速度浇注出多规格铸坯。介绍了测试新型浸入式水口流动性能的数值模型和物理模型的试验。采用URANS方法瞬态CFD模拟表明,新型浸入式水口流出的钢液瞬态行为稳定,因而弯月面以下钢液流速较慢,其效果还通过水模拟得到了验证。现场试验是在中国台湾的中钢公司进行的,试验结果表明,通过优化结晶器内钢液的流动行为,结晶器液面波动明显减小,从而提高了产品质量。
The fluidity of molten steel in the mold of continuous casting machine seriously affects the quality of continuous casting billet, especially at the meniscus, the direct contact between molten steel and the mold powder and the entrapment caused by instability of the meniscus in the mold are One of the major causes of product defects, such as linear defects in cold-rolled sheets and surface defects in slabs. In the mold uneven lubrication, but also increase the danger of breaking the steel. Fluctuations in the meniscus are mainly caused by the violent turbulence and transient behavior of the molten steel in the immersion nozzle. Recently, casting different steels on a caster has become a major direction for steelmakers around the world. In order to meet the quality requirements of all steel grades, a certain casting speed is required for each steel grade. For conventional submerged entry nozzles, ensuring a favorable flow condition within the crystallizer is a challenge. Thus, there is a need for a new immersion nozzle than ever before to cast a multi-gauge slab at various casting speeds by maintaining the optimum flow of molten steel in the mold. The numerical model and the physical model test for testing the flow behavior of the new submerged entry nozzle are introduced. The transient CFD simulation using URANS method shows that the transient behavior of the molten steel flowing out from the new immersed nozzle is steady and the flow velocity of molten steel below the meniscus is slow. The effect of this method is verified by water simulation. The field test was carried out by China Steel Corporation in Taiwan, China. The test results show that the liquid level fluctuation in the mold decreases obviously by optimizing the flow behavior of molten steel in the mold, thus improving the product quality.