Multiphysics Model of the Hearth Lining State

Abstract

The blast furnace (BF) is a huge counter-flow reactor to produce pig iron. The molten pig iron and by-product slag are accumulated at the hearth of the furnace, from where they are regularly tapped. The campaign life of the BF is governed by the wear of the hearth refractory. Once the residual thickness of the hearth lining is critically low, it must be repaired during a long-term stoppage, which is quite costly. Therefore, it is essential to keep track of the residual lining thickness not only for the better planning of the relining but also for the operational safety (avoiding dangerous hearth breakthrough incidents). [1,2] Modern BFs are equipped with many thermocouples (TCs) in the hearth refractory because higher temperatures indicate a lower residual wall thickness. [3-7] However, the measured temperatures are also influenced by many other effects such as TC defects, brittle layers in the refractory hearth cooling conditions, production rate, temperature, and flow state of the hot metal within the hearth. The preparation of the measurement data is crucial and quite challenging. Existing models lack the comprehensive checks of the data plausibility or of possible effects unrelated to wear. [2] Therefore, the recorded TC data (usually denser than 15 min values) must be first filtered, e.g., by excluding the time intervals influenced by stoppages. Then, strange behaviors like sudden temperature drops or uncorrelation to other TCs must be identified, which can be used to assess TC plausibility. An inverse heat transfer model is developed and presented in this study to estimate the 3D hearth wear profile. The model uses the prepared and weighted online TC measurements. The numerical computations are performed using COMSOL Server. The LiveLink for MATLAB module is utilized for the 3D hearth wear geometry interpolation and optimization. Furthermore, a COMSOL application is programmed so that a standard web browser can be used to visualize the results interactively on any device connected to the internal network without local software installation. The new model provides a flexible platform to include other physical aspects that are important for operational hearth monitoring. For instance, the thermal stresses and the deformation of

Dead-Man Behavior in the Blast Furnace Hearth—A Brief Review

“…Still, it should be kept in mind that the accuracy of erosion models depends on the validity of the modeling assumptions. In particular, brittle lining layers of low conductivity may lead to inaccurate estimates of the progress of the erosion profile, and the occurrence of such should be detected by other means [56,57]. erosion experienced during the campaign.…”

Numerical Analysis of Blast Furnace Hearth Drainage Based on a Simulated Hele–Shaw Model

“…The model demonstrated that viscous fingering may occur as the liquid-gas interface was near the outlet during the simulation. Kaymak et al [23] developed a simplified 3D CFD model to simulate the tilting of both slaggas and slag-iron interfaces during the hearth tapping process. To reduce the computational load, instead of the common used multiphase flow model, a single slag phase flow in coke packed bed with two moving interfaces has been formulated and implemented in this model where the interface movements were modelled by the moving mesh physics.…”

Operational application of numerical modelling for evaluation of hearth condition over a blast furnace campaign: Whyalla No. 2 Blast Furnace 4th campaign

“…In practice, to help explain refractory temperature measurements and locate the 1150°C isotherm, numerical modelling has been applied and can be classified into two categories: (1) refractory conduction modelling, for one-, two-or three-dimensional (1D, 2D or 3D) conditions within the hearth refractory [3][4][5][6][7][8]; (2) modelling based on coupled fluid flow, heat and mass transfer in a domain including hearth refractory and the molten liquid bath [4,[9][10][11][12][13][14][15][16][17][18][19][20]. The former is mainly based on the inverse heat conduction technique considering heat transfer in the refractory and skull (solidification layer) while the latter provides more information about molten iron (and slag) flow and the heat transfer within the hearth.…”