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Research On Numerical Simulation Of The Multi-field During Gas Preheating And Baking Process In The Drained Aluminum Reduction Cells

Posted on:2006-04-11Degree:MasterType:Thesis
Country:ChinaCandidate:Z Q WangFull Text:PDF
GTID:2121360182968110Subject:Thermal Engineering
Abstract/Summary:PDF Full Text Request
The preheating process in the aluminum cells is very important to the cells life, but the structure of drained cells makes it difficult. So the research on the preheating process is very significant to the research and design of drained cells. As a sub-project, the basic design and research of drained aluminum reduction cells (G1999064903 ) , the multi-field during gas preheating and baking process in the drained cells was researched by means of numerical simulation.According to the literatures, the numerical simulation method was widely applied to the research on the conventional aluminum reduction cells and obtained notable results. Relative to the static state, few researches on the preheating and baking process in the aluminum reduction cells were carried out and related report of the research on the gas preheating and baking process in the drained cells was not discovered.The mathematical model of flow field, temperature field and thermal-stress field during gas preheating and baking process in the aluminum reduction cells was established in the paper. The multi-field in half of the conventional 160kA cells was numerically calculated with commercial software FLUENT and ANSYS. The calculated results were compared with the testing data and related literatures and the mathematical model and calculation methods were validated.The flow field and temperature field during gas preheating and baking process in the 156kA drained cells were calculated with the validated model. The results show that:(1)Using the same disposition method of the burners in the drained cells, the average temperature on the cathode carbon surface reaches 910 ℃, 846℃ in the drains and 64.1℃ on the bottom shell after 72 hours gas preheating and baking. So gas preheating and baking can basically meet the technical requirements of the start-up process.(2) Compared with the coke preheating and baking, the average temperature in the ramming paste adhering to the cathode reaches 720℃ and the paste is fully baked, which shows the advantages of gaspreheating and baking.(3) In order to improve the uniformity of temperature on the cathode carbon surface, the angle of the end burner was adjusted and the temperature field under different angle (such as 10°, 15°, 20°and 30° ) was calculated. The results show that the optimal angle is 15-20°.Based on this, the thermal-stress field in the drained cells is simulated. The results are as follows:(1) After gas preheating and baking for 72 hours, the maximum displacement of the drained cells reaches 6.17mm.The maximum thermal-stress is in the contact part of the end steel shell and the cradle and the largest thermal-stress in the cathode carbon is located in the slot corners. .( 2 ) When using the semi-graphitizing cathode carbon, the temperature of the drained cells increases. The maximum displacement increases by 0.84mm and the maximum thermal-stress of the shell increases by 57MPa. While the maximum thermal-stress of the cathode carbon keeps the same and the average thermal-stress of the drains reduces 2.3MPa. Considering the deformation of the cathode carbon is the key factor to the cells life, the semi-graphitizing cathode carbon is suggested to be used in the drained cell instead of ordinary cathode carbon.
Keywords/Search Tags:drained aluminum reduction cells, gas preheating and baking, flow field, temperature field, thermal-stress field, numerical simulation
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