Effective Method for Temperature Equalization of a Slab in Continuous Casting-Direct Rolling

本研究旨在阐明一种新提出的用于连铸-直接轧制（CC-DR）过程中板坯的带辐射转换器的温度均衡器的传热性能。本文的温度均衡是气体焓与热辐射之间的有效能量转换方法在多孔介质中的应用，由于考虑的传热系统是瞬态导热、对流和辐射传热的耦合，因此本文首先对对流传热的影响进行了基础性研究。根据数值计算得到的板坯周围层流流场，预测了板坯内部的瞬态导热。对于具有实际意义的湍流流场，进行了中温传热实验，积累了各种工况下的系统数据，并利用尺寸约为实际尺寸五分之一的模型均温器进行了高温实验。为了模拟CC-DR过程，在实验中，均匀预热的模型板坯首先通过热辐射冷却，然后被送入温度均衡器。通过对铸坯瞬态温度的测量，证明了辐射转换器由于铸坯边缘的局部加热而使铸坯温度迅速均衡。此外，对温度均衡器中的总能量平衡的估计表明，如果从温度均衡器流出的可用能量被回收，则有效的温度均衡是可行的。除了这些调查之外，还进行了现场试验，并由Kinto在大同钢铁公司讨论了本边缘加热器的可行性。在CC-DR边缘加热器的设计和将辐射转换器引入工作设施方面具有足够的经验。

This study aims at clarifying heat transfer performances of a newly suggested temperature equalizer with the radiative converter for a slab in the continuous casting-direct rolling (CC-DR) process. The present temperature equalization is an application of the effective energy conversion method between gas enthalpy and thermal radiation by using porous media.Since the heat transfer system considered here is very complex owing to the conjugation of transient conductive, convective and radiative heat transfer, a fundamental study was carried out first by focusing attention on the the effect of convective heat transfer. On the basis of the numerically calculated laminar flow field around the slab, the transient heat conduction wihtin the slab was predicted. For the turbulent flow field which is of practical importance, the heat transfer experiment was conducted at a moderate temperature, and the systematic data for various conditions were accumulated.The high-temperature experiment was made by using the model temperature equalizer which is about one fifth of the actual one in dimensions. To simulate the CC-DR process in the experiment, the uniformly preheated model slab was cooled first by thermal radiation, and was subsequently fed into the temperature equalizer. By measurements of transient slab temperatures, it has proved that the radiative converter equalizes the slab temperature quickly owing to the local heating of the slab edge. Furthermore, the estimation of the overall energy balance in the temperature equalizer has demonstrated that efficient temperature equalization is feasible if the available energy flowing out of it is recovered.In addition to these investigations, the field tests were made and the feasibility of the present edge heater was discussed by Kinto in Daido Steel Co., Ltd. who has enough experience in designing the edge heater of CC-DR and in introducing the radiative converter into the working facilities.