H.-P. Rüther’s research while affiliated with ThyssenKrupp AG and other places

Thyssen Krupp Steel (TKS), Duisburg, Germany has developed and implemented a new electromotive forces (EMF) measurement-based method for continuous assessment of liquid iron filling levels and dead man position inside its Schwelgern blast furnace (BF) No. 2. The EMF measurements are performed by measuring the potential differences between multiple measuring positions at the blast furnace cell and a reference point. Four EMF sensors are installed at the circumference close to the blast furnace tapholes (TH) and four such sensors are installed above the TH, at the tuyere level (TU), while one sensor is installed as reference point (RP) at ground level, to perform EMF measurements. Each of these EMF sensors consists of a mounting link, welded to the blast furnace shell, an isolated cable, and a Pt100 thermocouple, for monitoring the sensor temperature, while all individual EMF signals are balanced to each other, to avoid irregular partially strong disturbances and and unknown signal drift.

Blast furnace hearth life is of major importance for economic efficiency and safety of the blast furnace process. Strong wear leads to a shortening of blast furnace campaign life and increases the risk of a possible blast furnace breakout. Hence, the blast furnace operator has to define a capable tapping strategy to reduce the wear of the hearth lining. This requires the knowledge of the actual blast furnace hearth conditions as well as the actual amount of tapped hot metal. Recently applied methods for determination of hot metal mass flow rates are located further downstream the process line which, in turn, do not enable an on-line measurement. Two new approaches for continuous determination of hot metal mass flow rates were tested by Betriebsforschungsinstitut VDEh-Institut for angewandte Forschung GmbH in laboratory trials at a physical model of the iron runner system as well as in operational trials at blast furnace 2 of ThyssenKrupp Stahl AG in Schwelgern. Thereby, the approach of hot metal mass flow rate determination by measuring the filling level within the iron runner has been proved suitable for operational practice. Herein, the wear of the iron runner is taken into account by a statistical wear model. Based on these investigations, a suitable method for continuous on-line measurement of hot metal mass flow rates has been made available for the first time at one iron runner of a multiple taphole blast furnace.

Owing to the concentration of hot-metal production on a few large-capacity blast furnaces only, it is imperative to fully use all technical opportunities for extending the blast furnace campaigns. The design and the layout of blast furnaces together with the blast furnace operation are the most important criteria for the campaign life. The admittedly high level of the state of the art, at the same time be regarded as a challenge for the future to expand the available know-how to ensure minimization of the abrasive, thermal and chemical wear and as such to massively extend the service life of all units of an integrated furnace plant.