Short‐term Lining Temperature Changes during Tapping in a Blast Furnace

Abstract

The following paper presents a three‐dimensional heat transfer model of the blast furnace hearth. The model has been developed with the objective of studying the short term changes in lining temperature during regular tappings. It is based on the actual conditions of Blast Furnace No. 2 at SSAB Oxelösund in Sweden. The model was evaluated and analysed using thermocouple data from the operating furnace. The study showed that a layer of tap clay around the tap hole had a significant effect on the heat transfer by reducing the heat variations in the lining. More specifically, a layer of 10–15 cm gave the best correlation between calculated and thermocouple data. A simulation was performed where the melt temperature and the tap cycle duration was based on process data from the operating furnace. Moreover, the size of the area subjected to changes due to the regular tappings was defined. It was found to be the region within an angle of 13° from the tap hole, 0.9 m above and 0.8 m below the tap hole.

Interpretation of Tap Induced Cyclic Temperatures in the Blast Furnace Lining

“…The mathematical model used in this study was developed by Swartling et al17 and was originally described in detail: only a brief summary is given below, where also minor modifications of the model are stated.…”

“…The geometry was created and meshed in Gambit version 2.3.16 22. The dynamic temperature distribution in the hearth lining was estimated in an earlier study 17. Based on the calculation results, cells with large temperature gradients were identified and split into smaller cells.…”

“…The duration of each phase in the tap cycle is determined based on process data from the operating furnace. The size of a time step in the simulation is 10 s. In the original model17 the time step size was 1 s, but calculations with time steps between 1 and 10 s were found to yield identical results. The calculation scheme is presented in Table 1.…”

“…As for the wall and bottom boundary conditions, a brief description follows. For a more detailed description, the reader is referred to 17. The upper wall, the symmetry plane through the taphole and the intersection plane that delimits the domain are treated as adiabatic walls, meaning that no heat is transported across these boundaries.…”

“…The authors have previously developed a three‐dimensional transient heat transfer model of the taphole region in a blast furnace 17. The model was based on the actual conditions of Blast Furnace No.…”