Dynamic Model of Basic Oxygen Steelmaking Process Based on Multi-zone Reaction Kinetics: Model Derivation and Validation

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THE basic oxygen furnace (BOF) has been a leading route of steel production for more than six decades and become mature in terms of safety, stable operation, and maximization in productivity. However, nowadays it faces different challenges, e.g., strict quality control, minimizing energy cost, maximizing yield, and reducing environmental pollution. Focusing on improving the process by developing fundamental understanding and enabling dynamic correction is the crucial step to optimize

BAPIN KUMAR ROUT, GEOFF BROOKS, and M. AKBAR RHAMDHANI are with the Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122. Contact e-mail: [email protected] ZUSHU LI is with the WMG, University of Warwick, Coventry, CV4 7AL, UK. FRANK N.H. SCHRAMA and JIANJUN SUN are with Tata Steel, Building 4H16, PO Box 10000, 1970 CA, IJmuiden, Netherlands. Manuscript submitted June 23, 2017.

METALLURGICAL AND MATERIALS TRANSACTIONS B

the BOF process. A dynamic model that can explain the changes in the critical process parameters based on the events taking place in the furnace operation is a must-have tool for the operators. It can be a base to develop an automatic control system of the process. Therefore, in the recent years, there has been an increasing amount of literature focusing on developing computer-based dynamic models for the BOF process.[1–13] Kattenbelt and Roffel[9] developed a dynamic model for BOF based on the measured step response of control variables such as oxygen flow rate, lance height, and flux addition. Although the authors discussed the mechanism of decarburization reaction based on the work of droplet generation, the size of droplets, and residence time in the emulsion, no fundamental relationship to include these parameters was employed in this work. Li et al.[12] applied the three-stage decarburization theory and applied three separate equations to simulate the decarburization rate. The rate equations were modified with the bath mixing degree, which was described as a function of dynamic lance height. The rate constants of

the equations were derived by fitting the data from 67 heats. Similar to Kattenbelt and Roffel,[9] the dynamic model developed by Li et al., cannot provide a physical insight into the BOF process due to the empiricism involved in deriving the rate parameters. Understanding that the BOF process rarely attains thermodynamic equilibrium,[14] the principle of chemical kinetics has appealed to many researchers in quantitative prediction of the refining rates. Several researchers[6,7,10] have applied the ‘‘coupled reaction mechanism’’ developed by Robertson and colleagues[15] to simulate the slag–metal reactions. Pahlevani et al.[6] employed the coupled reaction mechanism in a single-zone kinetic model with the flux dissolution model to simulate the BOF refining reaction. Ogasawara et al.[7] constructed a dynamic model for dephosphorization by combining coupled reaction model with a dynamic FetO generation model. An oxygen balance method combined with the off-gas data w