Abstract Scope |
At the most basic level, direct current (DC) busbars in a potline enable the electrochemical reduction of alumina by delivering current from the rectifiers to the cells and, therefore, can be seen as the circulatory system of a smelter. The busbars are carefully designed to obtain adequate current distributions in the pot collector bars, the pot-to-pot circuits, the pot risers, and the liaison busbars (passageways, input and output) circuits, and must be designed to allow short-circuiting of the pots for relining. With the trend of amperage creep in many smelters, the busbar systems are experiencing increased temperatures due to the increased current densities, leading in some cases in failure of electrical insulators and in excessive thermal expansion causing mechanical damage to different components, for example plate joints, laminated sheets expansion joints, or concrete supports. To address these issues, a suite of physics-based numerical models based was developed over the past 15 years to assess both the thermoelectrical (TE) and thermomechanical (TM) behavior of high-amperage DC conductors. These tools were used successfully in the amperage creep of several potlines operating different reduction technologies, both in the planning phase to prevent issues, and after the fact for diagnostics and debottlenecking solution development. The versatility of the modeling methodology also enables the detailed design of new busbars, such as booster section input and output circuits, of magnetic compensation loops and of emergency, repair and construction bypass bridges. |