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

Abstract

The smooth drainage of produced iron and slag is a prerequisite for stable and efficient blast furnace operation. For this it is essential to understand the drainage behavior and the evolution of the liquid levels in the hearth. A two-dimensional Hele-Shaw model was used to study the liquid-liquid and liquid-gas interfaces experimentally and to clarify the effect of the initial amount of iron and slag, slag viscosity, and blast pressure on the drainage behavior. In accordance with the findings of other investigators, the gas breakthrough time increased and residual ratios for both liquids decreased with an increase of the initial levels of iron and slag, a decrease in blast pressure, and an increase in slag viscosity. The conditions under which the slag-iron interface in the end state was at the taphole and not below it were finally studied and reported.

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

“…To verify the model, some cases with different initial oil‐layer thicknesses ( h oil,0 ) were studied. The simulated results and associated experimental data [ 12 ] were collected and are presented in Figure 3 , which shows an excellent agreement between the experimental and simulated tapping times for the different values of h oil,0 . Thus, the accuracy of the CFD model is demonstrated.…”

“…Table 2 of ref. [ 12 ] ), three grid resolution scales were examined: a coarse scale with 96 000 cells, an intermediate scale with 226 901 cells, and dense scale with 364 987 cells. The tapping time for the three cases was found to be 3.55, 3.69, and 3.65 s, respectively.…”

“…on the liquid interfaces, outflow patterns, gas breakthrough time have been investigated by several authors. [ 7,10–12 ] For gaining a deeper understanding of hearth drainage, some computational models have also been established. Nouchi et al [ 13 ] developed a simplified mathematical model to quantify the effects of some operational factors (such as production rate, initial taphole opening level, and low permeability zone) on the liquid levels and liquid outflow ratio.…”

“…A common problem of experimental and numerical studies of BF hearth drainage in the literature is that they report results under strongly limited conditions and usually only for a few runs. By contrast to 3D models, a 2D Hele–Shaw model combined with a method for automatic image processing [ 12,25,26 ] is an ingenious experimental device by which hearth drainage can be quantified and visualized, but it is still quite toilsome to undertake the experiments because the slot model has to be carefully cleaned between the experiments (to remove oil that sticks to the glasses). Furthermore, it is not easy to examine the effect of certain factors, like coke‐free zone and permeability of the packed bed.…”

“…Furthermore, it is not easy to examine the effect of certain factors, like coke‐free zone and permeability of the packed bed. Considering these challenges and the advantages, including low labor cost, ease to change the geometry and conditions, a VOF‐based CFD model was established to simulate the tapping of a Hele‐Shaw model that was used in the earlier work by the authors [ 12,25,26 ] to theoretically verify the experimental findings and to complement them. For the VOF method, appropriate computational grid size and arrangement are essential to describe the interface shape accurately.…”