Optimization of mixing time in a ladle with dual plugs

Abstract

Based on the two-phase fluid (Eulerian-Eulerian) model, a mathematical model about the gas-liquid flow and mixing behavior was developed to investigate the effect of the offset of dual plugs, the included angle of dual plugs with a center point, and gas flow rate on the mixing time in a ladle with dual plugs. Numerical results indicate that two types of recirculation zones exist in the ladle. One is the middle recirculation between gas and liquid plumes, and the other is the sidewall recirculation between plumes and the ladle sidewall. The correction shows that the mixing time is in proportion to −0.2676 power of gas flow rate. There is a unique optimum offset of dual plugs with a particular included angle, in turn, a unique optimum included angle of dual plugs exits with a particular offset.

Effect of Gas Blown Modes on Mixing Phenomena in a Bottom Stirring Ladle with Dual Plugs

“…In previous studies, 6,15,18,22,30) only one electrode was put into certain position of a ladle. However, the electrical conductivity value might vary when the electrode was put at different positions.…”

“…In the previous studies, there were two different views about the effect of plug positions on mixing time. Some investigators 6) reported the mixing time varied drastically when the plug moved from 0.5R to the wall, but the tendency was different at various angles. However, the results of Terrazas et al 30) showed that mixing time did not experience major changes when the plug position moved close to the wall.…”

“…Moreover, for high-capacity ladles used in many steel factories of China, two porous plugs are usually utilized, and their positions and relative angle have effect on the homogenization of molten steel. 1,6) For the function of argon gas in ladle refining, many studies were performed in the earlier years through water model 1,2,4,6) and mathematical simulation 5,[7][8][9] from different aspects such as (a) gas injection and transport, [10][11][12][13] (b) the effect of top slag layer, [14][15][16][17][18][19] (c) stirring and mixing. [20][21][22][23][24][25][26][27][28] In 1975, Nakanishi et al 10) investigated the correlation between gas mixing efficiency and mass transfer in a model ladle and explained this correlation with turbulence theory.…”

Optimization of the Mixing Time Using Asymmetrical Arrays in Both Gas Flow and Injection Positions in a Dual-plug Ladle

“…José de Jesús VILLELA-AGUILAR, 1) José Ángel RAMOS-BANDERAS, 1) * Constantin Alberto HERNÁNDEZ-BOCANEGRA, 1,2) Antonio URIÓSTEGUI-HERNÁNDEZ, 1) and Gildardo SOLORIO-DÍAZ 3) March 13, 2020) In this work, the multiphase mathematical simulation (steel-argon-slag-air) was used to improve the mixing time in a secondary refining ladle, which is validated with a physical scale model using dye tracer dispertion and measurement of mixing time. An experimental 3 k-p design was performed to optimize the number of cases and analyze the effect of injection gas flow arrangement.…”

“…Mixing time (τ mix ) is defined as the time at which there is a chemical homogeneity of 95% in steel. 1) There are several physical and chemical mechanisms involved in mixing, such as molecular diffusion of alloys, turbulent diffusion caused by recirculations and convective flows promoted by steel movement. 2) Argon injection is commonly performed through porous plugs located at the bottom of the ladle, promoting the exchange of momentum from the argon bubbles of the plume.…”