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带辐射转化器的板坯连铸直轧（CC-DR）过程温度均衡器的传热性能。目前的温度均衡是利用多孔介质实现气体焓与热辐射的有效能量转换方法的一种应用。由于这里考虑的传热系统是瞬态导热、对流和辐射传热耦合的，非常复杂，因此首先对对流传热的影响进行了基础研究。在数值计算板坯周围层流场的基础上，对板坯内部的瞬态热传导进行了预测。对于具有实际意义的湍流流场，在中等温度下进行了换热实验，积累了各种条件下的系统数据。采用尺寸约为实际温度均衡器五分之一的模型温度均衡器进行了高温实验。为了模拟实验中的CC-DR过程，将均匀预热的模型板先通过热辐射冷却，然后送入温度均衡器。通过对板坯瞬态温度的测量，证明了辐射转炉由于板坯边缘的局部加热，使板坯温度迅速均衡。此外，对温度均衡器中总能量平衡的估计表明，如果流出的可用能量被回收，则有效的温度均衡是可行的。在此基础上进行了现场试验，并对该炉边加热器的可行性进行了探讨，该炉边加热器在大同钢铁有限公司的设计和辐射转炉的应用方面具有丰富的经验。

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.