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直流炉作为炼钢电弧炉最初的型式,在上世纪80年代中后期才开始进入真正的工业应用并被大规模建造。随后在实践中逐渐发现和证实了直流炉所存在的问题,例如底电极问题,这使得人们对其优越性产生了怀疑。作为四种主要的底电极型式之一,水冷钢棒式底电极自发明以来已经历了超过20年的使用实践。然而,就作者看来,迄今为止仍未获得关于水冷钢棒式底电极熔损机制的科学认识。为解决这一复杂的问题,作者建立起一套完备的数学模型。在该模型中,首次耦合了传热与流动,特别地发现并引入了电磁效应的影响,还建立起钢棒与铜套间隙效应的估算方法,因而得以解释所观察到的实际现象。计算结果表明电磁力的轴向分量是驱动电极孔穴内流动的基本因素,而焦耳热并不占冷却水带走热量之主要部分。计算和分析得到了一个重要结论,即改变底电极直径会产生一种两面效应。因此提出了一种底电极的变直径结构,预计该结构在改善底电极热状态方面会带来明显的效果。
As the first type of steel-making electric arc furnace, DC furnace started to enter the real industrial application and was built on a large scale in the late 1980s. Then in practice gradually discovered and confirmed the problems existing in the DC furnace, such as the bottom electrode problem, which led to the suspicion of its superiority. As one of the four major bottom electrode types, water-cooled steel rod bottom electrodes have undergone more than 20 years of use since their invention. However, to the author’s opinion, no scientific understanding of the mechanism of meltblown rod-bottom melting has so far been obtained. To solve this complex problem, the author establishes a complete set of mathematical models. In this model, heat transfer and flow are coupled for the first time, in particular the effects of electromagnetic effects are discovered and introduced, and a method of estimating the gap effect between the steel rod and the copper sleeve is also established, thereby explaining the observed real phenomenon. The calculation results show that the axial component of the electromagnetic force is the basic factor of the flow in the driving electrode cavity, while the Joule heat does not account for the major part of the cooling water. An important conclusion has been obtained by calculation and analysis that changing the diameter of the bottom electrode produces a bimodal effect. Therefore, a variable-diameter structure of the bottom electrode is proposed, and the structure is expected to bring about significant effects in improving the thermal state of the bottom electrode.