热-电-机械性能数值模拟计算石墨化过程电极应力

Numerical calculations of the stress in electrodes during the graphitization using measured data of thermo-electrical-mechanical material properties

电极在石墨化过程中,当切应力超过了炭材料的抗拉强度时可能产生径向裂纹。新炉投产之初通常采用保守的功率曲线,这样会导致石墨化周期长,能耗高的后果。热处理过程中应力不仅受电极的机械和热性能变化的影响,还受到因不可逆性收缩和气胀造成的尺寸变化的影响。在内串中试石墨化炉测试了一批UHP电极焙烧品径向和轴向膨胀过程应力变化。利用获得的中试内串石墨化炉的膨胀数据,完成了应力分布的数值模拟计算。利用该分析工具,可以选择更合理的功率曲线,为降低能耗、提高产率,降低石墨电极废品率提供指导。

During the graphitization of electrodes,radial cracking might occur in case the tangential stress exceeds the tensile strength of the carbon material.During a new furnace start-up a conservative power curve is applied,this resulting in a long graphitization cycle and high energy consumption.A numerical calculation of the stress development in the entire electrode is useful for squeezing safely the graphitization cycle.The stress depends on the evolution of mechanical and thermal properties during the heattreatment but also on the dimensional changes of the electrode related to irreversible shrinkage and puffing expansion.A baked stock of UHP electrode was characterized for both aspects using a LWG pilot furnace measuring the dilatation on longitudinal and transversal cores.A numerical calculation of the stress distribution was performed using the pilot LWG expansion data.This tool will serve for guiding the selection of more aggressive power curves resulting in a scrap less production of graphite electrodes with minimum energy and maximum productivity.