Simulation Analysis on Fluid Mechanics around Skimmer and Separation Efficiency of Iron Dam in the Blast Furnace Main Trough

• Main Authors: Guan-Jia Lai, 賴冠佳
• Other Authors: 鄭文桐
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/50935934848817855682

碩士 === 國立中興大學 === 化學工程學系所 === 104 === Iron and steel industry is the fundamentals of economic development. Aside from pursuing higher productivity, it is also important know how to produce higher quality steel at the competitive price. However, the blast furnace main trough is worn by molten iron and slag, which has expensive repairs. It’s essential to investigate fluid mechanics and separation in blast furnace main trough. Therefore, in the present work a computational fluid dynamics model has been developed to study the transient flow behavior of air, liquid iron and slag in the blast furnace main trough. We investigate the effects of bottom shape of the blast furnace runner, the height of the opening under the skimmer, the total mass flow rate and the ratio of iron to slag on the flow patterns and separation efficiency at iron dam. In addition, the mathematical model is isothermal and turbulent flow to simulate velocity distribution by utilizing the finite volume method and multiple-phase fluid model (VOF method), respectively, followed by calculating shear stress on the wall of trough and mass flow rate to estimate the separation efficiency of iron and slag at the iron dam. The significant results of this study were summary as follows: (1)Two phase system(iron and air) In the buffer zone of blast furnace trough, the maximum shear stress is occurred in the front of iron dam, which the maximum shear stress of obtuse runner is over that of arc-shaped runner for 25.58% because the recirculation in obtuse runner is more than arc-shaped runner. (2)Three phase system(iron, air and slag) a.The shear stress around skimmer of blast furnace trough will raise due to slag loss (slags fall into the iron dam through the bottom of skimmer). The more slag loss in iron dam will cause the higher velocity and the greater shear stress. As slag loss percentage was increased from 0% to 3.06%, the shear stress behind skimmer would be raised by 1.79%. b.When the ratio of iron to slag was set by 1:9, the total mass flow rate was fixed as 15 ton/min from taphole, and the height of the opening under the skimmer was increased from 0.3m to 0.4m, the maximum shear stress in the front of iron dam was raised by 65.89%. c.As the total mass flow rate was changed from 5.5 ton/min to 15 ton/min, the maximum shear stress in the front of iron dam was increased by 45.74%, resulting from that higher velocity owing to reducing the residence time. d.When the height of the opening under the skimmer was changed from 0.4m to 0.3m, the slag loss percentage was decreased from 3.06% to 0% due to the fact that the interface between iron and slag is lower than the bottom of skimmer. e.The slag loss percentage would be raised by 1.63% when the total mass flow rate was changed from 5.5 ton/min to 15 ton/min for reducing the residence time. f.With adding the amount of slag in trough, the interface between iron and slag is lower than the bottom of skimmer. As the ratio of iron to slag at taphole was enhanced, the slag loss percentage will be increased from 0% to 1.58%.