| 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:â‘ Aiming 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.â‘¡Using 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 > |
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