Model for Fast Computation of Blast Furnace Hearth Erosion and Buildup Profiles

Brännbacka, Johnny; Saxén, Henrik

doi:10.1021/ie800384q

Cited by 20 publications

(44 citation statements)

References 12 publications

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“…8,13,16,17) Similar transients with falling and rising hearth plug and sidewall temperatures have been reported by other investigators. [18][19][20][21] The exact reasons for these cycles are not known, but a plausible theory in the furnace studied is that triggering factors are changes in the radial distribution of the liquids entering the hearth caused by permeability changes in the coke bed (dead man).…”

Section: Lining Temperatures and Heath Volumesupporting

confidence: 86%

“…Several two-dimensional hearth erosion models have been described in the literature. [11][12][13][14][15] The model used in the work reported in this paper 8) applies a two-dimensional problem formulation, interpolating a three-dimensional profile of the hearth from several two-dimensional profiles. The results of the estimation can be illustrated in many ways, e.g., in terms of cross sectional views (cf.…”

Section: Lining Temperatures and Heath Volumementioning

confidence: 99%

“…8) The analysis is partly motivated by cyclic changes observed in the hearth lining temperatures of the furnace studied, which seem to indicate that the radial distribution of the liquids in the dead man is disturbed, possibly as a result of permeability changes in the coke bed. On the basis of drilling core information, the quantification is realized by developing a blackbox model for the hearth state index, expressing the state in which the dead man is.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of the State of the Blast Furnace High Temperature Region by Tuyere Core Drilling

2009

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Tuyere core drillings give a unique opportunity to probe the blast furnace and detect changes in both physical and chemical conditions of its high-temperature region. In this paper the findings from drill cores taken from a blast furnace are used to characterize the internal state of the furnace hearth, quantified by an erosion model estimating the available hearth volume. The complex relation is studied by entertaining neural network models using different combinations of inputs consisting of the extent of the distinct tuyerelevel zones (raceway, bird's nest, dead man, etc.) of the core samples. The resulting model can be used to gain knowledge of the relation between tuyere level conditions and hearth states, and to classify the findings from future core drillings. The results also throw light on possible reasons for thermal cycles observed in the hearth of the furnace studied.KEY WORDS: tuyere core drillings; blast furnace; hearth state; neural network pruning. 203© 2009 ISIJ ternative, tuyere core drillings have been used at many plants since the 1990's 5-7) : A steel pipe is drilled into the furnace through an opened tuyere at a stoppage, and the pipe with its core filled with the bed is withdrawn, quenched and opened for analysis. Typically, the length of the distinct regions, the particle size of the coke, the metallurgical and mineralogical state of the materials and the presence of iron and slag in the sample are analyzed.Tuyere drillings are performed regularly at Rautaruukki's two blast furnaces during shorter stoppages.9) The sample tubes are 5.5 m long and the withdrawn core has a diameter of 205 mm; typically, the core length is shorter than the maximum drill penetration, l max , into the bed due to compression of the core. The drill penetration, in turn, depends on the physical state of the dead man. After drilling, the core samples are analyzed physically and chemically. In the present work, the modeling effort is focused on the lengths of the different sections identified in the drill core (cf. Fig. 1). Based on the characteristics of the sampled coke and iron, the core is divided in to six regions (with the corresponding number given in parentheses): (1) bosh, (2) flame, (3) raceway, (4) bird's nest, (5) iron agglomerate, and (6) dead man, and their lengths l i (iϭ1...6) are recorded. The difference between the maximum penetration of the drill and the total core length, l c ϭ∑ 6 iϭ1 l i represents the total compression of the sample, Dlϭl max Ϫl c . These lengths from twenty two drill core samples from one of the Rautaruukki furnaces were used for modeling (cf. Table 1). Figure 2 shows a photograph of a core with the different regions indicated. Lining Temperatures and Heath VolumeThe internal state of the furnace hearth can be assessed on the basis of refractory temperatures measured by thermocouples in the hearth bottom and sidewall lining. These temperature measurements can be used to estimate the remaining thickness of the lining and also formation of buildup material (skull) on the hot fa...

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Section: Lining Temperatures and Heath Volumesupporting

confidence: 86%

Section: Lining Temperatures and Heath Volumementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of the State of the Blast Furnace High Temperature Region by Tuyere Core Drilling

2009

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“…If the hearth relining is scheduled too late, there is a risk of an outbreak with potentially catastrophic consequences. On the other hand, a too early relining of the hearth causes unnecessary loss of production and capital [4]. This paper thus presents a model to better estimate the wear line of a blast furnace hearth.…”

Section: Introductionmentioning

confidence: 99%

“…Zhao et al [24] compared different characteristics of the allcarbon brick, such as the wear line, and the ceramic cup synthetic hearth bottoms. Brannbacka and Saxén [4] focused on the mathematical formulation of the problem, yielding a general model optimized for fast computation. Zagaria et al [23] present a model they call MUSA that combines online readings of temperatures and historical data to predict hearth erosion and the skull profile.…”

Section: Introductionmentioning

confidence: 99%

Comparison of Methods for Solving Inverse Problems to Estimate the Wear Line in a Blast Furnace Hearth

Magnago¹,

Catabriga²

2014

Proceedings of 10th World Congress on Computational Mechanics

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Interpretation of Tap Induced Cyclic Temperatures in the Blast Furnace Lining

Swartling

Tilliander

Saxén

et al. 2012

steel research int.

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The thermal behavior of the blast furnace hearth was studied using modeling. The focus was the effect of the size and shape of the taphole clay layer around the taphole. Four different cases have been calculated: one reference case and three cases with different taphole clay layer geometries. It was found that the calculated peak‐to‐peak amplitudes of the lining temperatures during the tap cycles at the location of a thermocouple can be approximated as a linear function of the taphole clay layer thicknesses for all calculated cases. Modeling was also done where both the 90th and the 10th percentile of the observed peak‐to‐peak values of the studied tap cycles were included to describe the behavior of the operating furnace. The taphole region can be divided into three categories based on how well the model can describe the measured process data: below, at, and above taphole level. Below the taphole level, the measured lining temperature variations are smaller than for the calculated results. At the taphole level, the model can describe the behavior well. Above the taphole level the measured lining temperature variations are larger than for the calculated results. It was concluded that in order to make a more accurate heat transfer model of the taphole region, the presence of a skull build‐up below the taphole, erosion above the taphole, and the bath level variations need to be taken into account.

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Model for Fast Computation of Blast Furnace Hearth Erosion and Buildup Profiles

Cited by 20 publications

References 12 publications

Assessment of the State of the Blast Furnace High Temperature Region by Tuyere Core Drilling

Assessment of the State of the Blast Furnace High Temperature Region by Tuyere Core Drilling

Comparison of Methods for Solving Inverse Problems to Estimate the Wear Line in a Blast Furnace Hearth

Interpretation of Tap Induced Cyclic Temperatures in the Blast Furnace Lining

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