The ultralow CO 2 steelmaking blast furnace process (ULCOS-BF) aims at minimising the CO 2 emissions of the BF by at least 50%. This process is based on the replacement of hot blast by oxygen, the recycling of hot decarbonated top gas into the lower shaft and normal hearth tuyeres, and the capture of CO 2 and its storage in a geological trap (full CO 2 capture and storage process). The paper highlights the main technologies of this process and the expected benefits for CO 2 mitigation. The ULCOS-BF has been demonstrated during three campaigns of 7 weeks each by coupling the LKAB experimental BF in Luleå to a pilot vacuum pressure swing absorption unit for CO 2 removal. The concept, preparation and results of the campaigns are described. 1 Technological improvements in BF process and development of reducing agent rate in Europe 1 ß 2013 Tata Steel Nederland Technology BV Published by Maney on behalf of the Institute
An off-line simulation model of the blast furnace hearth is developed based on mass balances for iron and slag, expression of the liquids outflow rates and logical conditions for the start and the end of the outflow of liquids. The dynamic model divides the furnace hearth into two regions of sizes that may change during the tapping process. It provides a description of the time evolution of the liquid levels and predicts the duration and the periods of iron-or slag-only flow in the beginning of the taps. The values of some model parameters are estimated on the basis of measurements in a reference blast furnace, while others are fixed. A sensitivity analysis of the model is provided, revealing the role of some key parameters. The model is demonstrated to describe the overall drainage behavior of the reference furnace reasonably well, and the presence of pools with different liquid levels can also be deduced from the real data. Finally, some recommendations for future work are suggested.
In blast furnace ironmaking hearth performance has a critical effect on the efficiency of the operations and the campaign duration. In this paper the relationship between hearth lining design and lining wear is analysed, based on plant data and research activities of Tata Steel Europe that is supported by information published elsewhere. Tools to model, monitor and visualise the hearth processes are discussed. Current hearth management practices are illustrated. It is noted that the varying process conditions make current campaigns less predictable than previous ones. The hearth lining design rules developed decades ago seem to be in need of revision.
A drainage model of a multi-taphole hearth of a (large) blast furnace operated by alternate tappings has been developed. The model, which is based on a simplified treatment of the pressure losses in the dead man, taphole entrance and taphole, can estimate the liquid levels and outflow rates of the two liquid phases in quasi-stationary and dynamic states. The sensitivity of the results to changes in the conditions, such as taphole length and diameter, dead-man porosity, as well as in the model parameters is illustrated. The effect of asymmetric conditions at the two tapholes, and dynamic responses of particular interest are also illustrated and discussed. The results of the model are finally compared with findings from a reference blast furnace where the outflows rates of iron and slag are routinely estimated, demonstrating that several of the typical outflow patterns observed in the furnace can be at least quantitatively reproduced. This demonstrates the feasibility of the model as a tool for gaining deeper insight into the complex drainage with alternating tappings and the evolution of the liquid levels in the hearth of large blast furnaces.
An on-line model of the liquid levels in the blast furnace hearth is developed based on mass balances, estimates of the production rates, and measurements of the outflow rates of iron and slag. To consider differences arising in the hearth when different tapholes are operated, the hearth is divided into m regions, characterized by individual iron and slag levels. The pools communicate with each other by cross-flow of iron and slag. To prevent drift in the liquid level estimates, a correction procedure is developed to make the levels stay within reasonable bounds. The model is applied to measurement data from a three-taphole blast furnace and is demonstrated to provide an on-line view of the in-furnace conditions. The liquid level estimates as well as the required corrections are illustrated and analyzed for cases with different model parameters, and an explanation of the required corrections is provided. The model is also evaluated with respect to its ability to predict the end of the taps. Finally, conclusions concerning the validity of the model are drawn and possible future developments of it are outlined.
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