Off-line Model of Blast Furnace Liquid Levels

Abstract

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.

Principal Component Analysis of Blast Furnace Drainage Patterns

“…The large hearth diameter in multi-taphole blast furnaces may give rise to zones of different coke-bed permeability, which leads to differences in the local conditions and liquid levels [18,19]. A mathematical model was developed by the present authors [14] and applied to study the effect of different parameters and variables on the liquid levels and drainage process. The hearth was modelled as two interconnected pools of liquids, where communication factors can control the flow from one taphole zone to the other.…”

“…Several studies in the literature have presented models of hearth drainage [1,2,[10][11][12][13]. A recent study by the present authors proposed a simple offline model simulating the liquid level fluctuations in a hearth with intermittent tapping [14]. By applying different conditions to each taphole, it was demonstrated that some outflow patterns and slag delays observed in a blast furnace could be mimicked.…”

Experimental Model Study of Liquid–Liquid and Liquid–Gas Interfaces during Blast Furnace Hearth Drainage

“…The initial l-l interface level (above the taphole) is related to the amount of accumulated molten iron in the BF hearth at the commencement of drainage, the dead man porosity, the level of the taphole, and the taphole length. For multi-taphole furnaces, it is also strongly related to the operation of the alternate taphole used [10,12]. The outer level of the taphole is predetermined for every BF, but the angle and the length of the taphole may vary.…”

“…For drainage of a hearth with a heterogeneous dead man, socalled viscous fingering may occur in the l-g interface close to the taphole [8,9]. Furthermore, for large BFs, it is estimated that the vertical level of the interfaces may vary in different parts of the hearth as a result of an impermeable dead man [10][11][12]. Such special phenomena can make the motion of the interfaces far more complicated than the expected overall behavior outlined above.…”

“…Detailed investigations of the interface phenomena have been conducted based on the general findings by Tanzil et al [3][4][5] and by Zulli [6]. Researchers have established simplified mathematical models estimating the l-l and l-g interface levels in the BF hearth as offline tools [10][11][12]14] or online based on measurement data [15,16]. Efforts have also been made to study the sophisticated interface phenomena by Computational Fluid Dynamics (CFD) [17] or a combination of this technique with the Discrete Element Method (CFD-DEM) [18][19][20].…”