| BF/BOF Interface that connects iron-making and steel-making is an important region in the manufacturing process of steel, which functions as a transition and has large bearing on the integration of the process of steel-making. The temperature of hot metal, on the other hand, is an important index throughout this critical region. Hot metal is the primary input material for steel-making, and its temperature decrease directly influences such important regions as pre-treatment, steel-making process, energy-saving, production management and ladle service life. The control of the temperature of hot metal is therefore, not only a necessity for the steel-making process, but also closely related to the reduction of energy of consumption and even the management of production. Hence, the problem of temperature drop during the transportation of hot metal has aroused immense concern. In the present thesis, previous studies on the this issue is summarized, based on which a theoretical model of the temperature decrease on BF/BOF Interface is established, from the study of heat-transfer and based on the principle of energy balance, and further applied to the production processes in An Steel and Shouqin to find the problems and present improvement measures.Based on the study of the heat transfer, the present thesis categorizes BF/BOF Interface into four different modes:the mode of hot metal with mixer ladle, the mode of hot metal charging ladle, the mode of hot metal in TPC and the mode of one open ladle. The mode of hot metal with mixer ladle generally results in considerable drop of temperature and, is thus outdated because it has two hot metal dumping processes, which makes the mode inconsistent, to compensate which extra heating is required. The mode of hot metal charging ladle is getting less and less used because of its lack of shock adjustability, although it has only one hot metal dumping process. In workshops with huge BF/BOF, the mode of hot metal in TPC is used most often because production with big BF requires transfer of large quantity of hot metal. The mode of one open ladle is the most promising mode of interface because it greatly reduces the temperature drop of hot metal as it uses hot metal tanks that match the capacity of the BOF to achieve a good interface continuity, which considerably decreases the time needed to manage the transportation of hot metal. Moreover, the models of temperature decrease are established for each mode and factors that influence the temperature decrease are analyzed and categorized as production layout, mode of interface, scheduling of hot metal transfer and specific operations.Research is.performed on the BF/BOF Interface at An Steel and Shouqin, two of the major steel manufacturers in China, and some major drawbacks are found and suggestions of improvement made. The analysis shows that, for factories like An Steel with innate production layout problems, improvements should be made on the layout and on the BF/BOF relationship, to the optimize the BF/BOF interface and to increase the temperature of hot metal transferred to BOF with improved specific operations. And for factories like Shouqin with advanced processes and simple BF/BOF relationship, the focus should be on the mode of BF/BOF interface, i.e., to use the mode of one open ladle. With the BF/BOF interface being optimized with the above-mentioned measures, the period of transfer of hot metal through the BF/BOF interface can be reduced by 85 min on average, and the temperature of hot metal transferred to BOF can be increased from 1260℃to 1348.6℃, which means a reduction of 32.74kgce in comprehensive energy intensity and a cost reduction of 6.8 Yuan, for each ton of steal. At Shouqin, the optimized BF/BOF interface is estimated to the reduce period of transfer of hot metal through the interface by 22 min, and the temperature of hot metal transferred to BOF can be increased from 1300℃to 1362.8℃, which means, for each ton of steal, comprehensive energy intensity can be reduced by 32.74kgce and the cost by 6.8 Yuan. |
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