【作者】 邓星球；

【导师】 李劼； 刘凤琴；

【作者基本信息】 中南大学 ， 有色金属冶金， 2004， 硕士

【摘要】 铝电解槽从通电焙烧、启动到转入正常生产的过程中,电热产生的高温和熔体的电化学作用会导致阴极内衬变形、隆起或开裂,最终因阴极破损（槽破损）而停槽。认识阴极内衬中的电—热—应力的形成与演变规律,进而采取各种有利于实现最佳的温度场与应力场分布的技术措施,对于减少槽破损,提高槽寿命具有重要意义。本文以160kA预焙铝电解槽为研究对象,在充分获取内衬材料物性参数的基础上,以ANSYS作为主要开发工具建立了完整的电-热-应力模型,着重研究了在不同电解工艺技术条件下阴极内衬中电、热分布规律和在不同阴极材质下电、热、应力分布规律。主要的研究内容及成果如下: ①针对稳态条件下的电—热—应力解析问题,运用有限元软件ANSYS建立起三维1/4整槽电—热—应力模型,并且在模型中既考虑了内衬材质的不均所形成的热应力,又考虑了温度梯度热应力和化学应力。与国外研究者所采用的切片模型及假设（即以一个阴极炭块组切片为研究对象,并假定温度场均匀且无化学应力）相比,本文建立的这种1/4整槽模型无论是计算结果的准确性还是研究的全面性均明显提高。 ②运用所建立的三维电热模型,研究了电解工艺条件由高温电解转变为低温电解后阴极内衬的热分布变化。研究表明,采用低温电解工艺,必须加强槽底保温方能保持阴极内衬中理想的温度分布状态。此外,通过研究阴极炭块种类对内衬中电热场的影响,发现随着炭块石墨含量的增加（或石墨化程度的提高）,炭块的温度梯度、炭块中的电压降以及电解槽槽底电压降显著降低,电解质凝固等温线往槽大面和小面方向偏移,但在耐火砖内位置变化不大。 ③在研究了阴极炭块种类对内衬中电热场的影响的基础上,研究了阴极炭块种类对阴极炭块内结构响应值以及应力表征值的影响,并用相应的强度理论判断其安全状况。结果表明,阴极炭块各断面中剪应力分布规律是τ_xy>τ_yz>τ_xz,τ_xy的最大值出现在端部炭块;阴极炭块中各方向正应力的分布规律是,除端部炭块外,使用石墨含量大于20%的无烟煤-石墨复合炭块（HC₅）时,σ_x>σ_z>σ_y,而使用石墨含量小于20%的无烟煤基炭块（CF₂）、石墨质炭块(HC₁₀)、纯石墨化炭块（K）时,σ_y>σ_x>σ_z;随着炭块石墨含量的增加,炭块总位移量、总应变量、X与Z方向最大位移量和最大正应力、XY和XZ面最大剪应力、第一和第四强度理论应力显著减小;而Y方向位移、YZ面的剪应力总体上随着石墨含量的更多还原

【Abstract】 From preheating and start-up procedure to the normal process of production, the cathode lining of aluminum reduction cell will always suffer deformation or crack due to high thermal shock caused by the thermo-electric factors and the electrochemical reactions occurring in the high temperature molten fluoride electrolyte, which will finally lead to cathode failure (pot failure) and production stopping. In order to decrease cathode failure and increase cell life, it is significant to study the forming and evolutive laws of stresses in the lining and then take various technical measures to realize optimal distribution of the stress field. In this thesis, with a sort of 160kA prebaked aluminum reduction cell as the research object, based on sufficient measured parameters of the lining materials properties and with commercial finite element software ANSYS as main tool, a thermo-electric-structural coupled model was developed. The emphases was laid on the study of the laws of the electric and thermal distributions in the lining under different technological conditions and on the study of the laws of the electric, thermal and stress distributions in the carbon cathodes made of different materials. The main research contents and achievements are as follows:①Aiming at the thermo-electric-structural analysis of the aluminum reduction cell under the static conditions, a 3D 1/4 Ml cell model based on ANSYS was developed, in which, all the stresses caused by chemistry, by temperature distribution as well as by the inhomogeneity of the lining materials were taken into account. The results were more precise and comprehensive compared with those of carbon cathode slice model used by some foreign researchers; the later only took the stress caused by the inhomogeneity of the material into account, ignoring those caused by chemistry and assuming that the temperature in the material was uniform.②Using the thermo-electric model, the changes of thermal distribution in the lining with the electrolytic technological conditions transforming from high temperature to low one were analyzed. The results showed that the heat preservation on the cell bottom should be strengthened when the low temperature technological conditions were applied. Besides, the influences of different kinds of cathode blocks on the thermo-electric distribution in the lining were studied. The results showed that, with the increase of the content of graphite or the graphitized degree in the cathode blocks, the thermal gradient and voltage drop in the cathode decreased greatly; the liquidus isotherms moved toward the end wall and side wall in the vertical direction, but moved little in the firebricks.on the study of the impacts of different types of cathode blocks on the thermo-electric distribution, impacts of cathode types on structural response and the stress token were studied, followed by the safety evaluation using relative intensity theories. The results showed that, in the blocks ,the shear stress Txy>Tyz>Txz, and maximal Txy appeared in the end block. Except for the end block, when anthracite-graphite block HC5 (of which the content of graphite is more than 20%) used, the main stress ax>az>ay, and when anthracite block(of which the content of graphite is less than 20%), graphite or graphitized block used, ay > ax ><jz . With the increase of the content of graphite in the blocks, the total displacement and strain, the displacement in X and Z direction, the maximal main stresses, the maximal shear stresses in XY and YZ surface, the first and third principle stresses and SEQV decrease greatly, which mean a safer cell.? Some exploring work was done on the transient model aiming at the coke-prebaked process. A 3-D 1/4 full cell transient model was build and 25 hours analysis was performed. The results showed the model was correct on the whole but needed further optimization. This study laid a foundation for the further study of the transient process.更多还原