8th International Congress on Science and Technology of Ironmaking - ICSTI 2018

Steelmaking following the blast furnace process route has a share of approximately 75 % of the worldwide steel production and thus is the primary source of steel. Due to the large size of blast furnaces and the extreme process conditions therein, the accessibility for measurements inside the furnace is very limited. Nevertheless, since the campaign life is closely related to the multiphase processes in the lower part of the blast furnace, the hearth, it is important to understand the observed phenomena. Mainly the transient movement of the packed coke bed (“floating” or “sitting” dead man), the shape of the resulting coke free region and their dependence on different operating conditions are of particular interest. In the past, various (experimental, analytical and numerical) models have been developed to understand and describe the interacting multiphase flow and the thermo-chemical processes inside the blast furnace. These models can be generally subdivided in continuum approaches at the macroscopic and discrete models at the microscopic scale. With increasing computational capabilities the discrete approaches, especially the Discrete Element Method (DEM), have been applied in many fields of research; for instance in geomechanics, physics, pharmacy and (chemical-)engineering. The great advantage of these approaches is the temporal and spatial resolution of the mechanical interaction among individual particles of different size and shape and with their surrounding in granular systems. Furthermore, it is possible to extend these approaches with CFD models to describe the interaction between solid, gaseous and liquid phases in technical, multi-phase systems. The publication presents a numerical DEM-CFD study of an isothermal blast furnace model of a plant located at the “AG der Dillinger Hüttenwerke” in Dillingen, Germany. The model is calibrated with specifically chosen boundary conditions derived from online measurements and process model calculations. With this calibrated model the impact of different liquid levels on the processes in the hearth is investigated. The results presented focus on particle movement, porosity distribution and the formation of coke free zones in the lower part of the furnace.