수모델을 활용한 정련 공정 효율 향상에 미치는 하부 노즐 패턴의 영향

Abstract

In the basic oxygen furnace, the removal of impurities in molten steel can be improved by using blowing system such as a top blowing and bottom stirring. There were many efforts to improve the refining abilities of blowing process by various water model. Water model is one of useful method for the visualization and investigation of dynamic flow due to the opacity of the steel making process. However, in case of double-nozzle, the effects of nozzle pattern and gas flow rate on the mixing time were not sufficiently investigated. In this study, the water model was designed based on the dynamic similarity of the industry condition. The effect of water height, nozzle radial position, nozzle radial angle and gas flow rate on mixing time was investigated in case of double-nozzle. The water model was designed by reducing the 350 tons of industrial scale to 1/20 scale, and the froude number was calculated for dynamic similarity. Firstly, 0.012 or 0.018 m3 of water was filled out the vessel and the same height of water was kept in vessel. To measure the mixing time using electrical conductivity, 3 ml of saturated KCl solution was injected in each experiment. Two electrical conductivity sensors were installed in the dead zone. The dead zone was assumed within 10 mm of height and width from the bottom and wall of vessel, respectively. 95 pct of the electrical conductivity was assumed to be the perfect mixing time. The measurement for each condition was repeated 10 to 20 times for the accuracy of experiment. In this study, the effects of water height, gas flow rate, nozzle radial position and nozzle radial angle on perfect mixing time were investigated by using water model. The perfect mixing time decreased as the gas flow rate increased.