On‐Line Estimation of Liquid Levels in the Blast Furnace Hearth

Abstract

An on-line model of the liquid levels in the blast furnace hearth is developed based on mass balances, estimates of the production rates, and measurements of the outflow rates of iron and slag. To consider differences arising in the hearth when different tapholes are operated, the hearth is divided into m regions, characterized by individual iron and slag levels. The pools communicate with each other by cross-flow of iron and slag. To prevent drift in the liquid level estimates, a correction procedure is developed to make the levels stay within reasonable bounds. The model is applied to measurement data from a three-taphole blast furnace and is demonstrated to provide an on-line view of the in-furnace conditions. The liquid level estimates as well as the required corrections are illustrated and analyzed for cases with different model parameters, and an explanation of the required corrections is provided. The model is also evaluated with respect to its ability to predict the end of the taps. Finally, conclusions concerning the validity of the model are drawn and possible future developments of it are outlined.

Drainage Model of Multi-taphole Blast Furnaces

“…The former signal is considered fairly accurate, while the latter is known to be more uncertain. [23] Despite potential inaccuracies, the signals reported in the historical database of the steel plant were used as such in this study. In analyzing the results, one should keep in mind that time lags caused by the main trough and runner may occur.…”

“…However, the models' results have only been compared to single measured outflow patterns and little work has been reported on model-based analysis of the different drainage patterns that are observed in real blast furnaces. [22,23] The computational requirement of CFD models still seems prohibitive for using this technique to mimic the drainage patterns observed in the real operation, considering the fact that several tap cycles have to be simulated until a quasi-stationary state is reached. Furthermore, it is also of interest to study dynamic responses, e.g., at disturbances or when the internal hearth conditions gradually change.…”

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

“…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].…”

Principal Component Analysis of Blast Furnace Drainage Patterns

“…Earlier studies of alternating tapping practice presented differences in taphole length, amounts of liquids extracted, and hot metal temperature between the operating tapholes [1,3,4]. Even though some correlations among production variables and erosion of both lining and taphole were established, little is known about what induces such variations and how.…”

“…Thus, the model makes it possible to theoretically evaluate the role of different parameters. Furthermore, an online liquid-level model was also proposed based on similar simplifications and assumptions, but using estimates of the production and outflow rates [4]. The model considers a division of the hearth into pools with individual liquid levels.…”