| 摘要 |
<p>Bottom electrodes (6) of direct current arc furnaces, especially during the overheating phase of the melting process, are subjected to very high thermal stresses. As a result of a melting bath flow brought about by electromagnetic forces, the heat supply from the overheated melting bath (13) to the bottom of the electrode(s) (6) is increased still further. This is manifested in a melting back of the metallic component (6') of the bottom electrode in the direction of the furnace crucible base (4). When both the metallic component (6') and the non-metallic refractory component (7') of the bottom electrode (6) are arranged in the direction of the electromagnetic field, that is, in the peripheral direction of the bottom electrode (6), the length (l) of the electrode component is greater than its width (b). Moreover, two zones form in the operating condition of the furnace; namely, an upper, non-metallic zone (7'), which is formed by the apex (7') of dams (7) projecting into the melting bath (13), and a lower zone, which is formed by the slightly melted-back, metallic component (6'). In this way, the metallic component (6') of the bottom electrode (6) is directly protected from the bath flow, and the intensive heat exchange between the melting bath (13) and the bottom electrode (6) is reduced. By inserting non-metallic, refractory components (7) into the bottom electrode, the periphery or diameter of the latter is increased. This measure reduces the electromagnetic field strength in the transition area from the bottom electrode (6) into the melting bath (13), and consequently an additional reduction in the melting bath flow is achieved at the same time.</p> |
