blast furnace performance and parameters.pptx

blast furnace

1. OUTLINE 2 / 13 Motivation Blast furnace overview Hearth Description Tapping Different cases of liquid flows Tilting of interfaces Drainage Performance parameters Summary

2. MOTIVATION 3 / 13 To have effective and undisturbed drainage of produced liquid iron and slag To enhance furnace stability, productivity, efficiency and life

3. Blast Furnace Overview 4/13 L. Shao -Doctor of Technology Thesis (2013).

4. Tapping and Different Drainage Cases   Tapping :Casting/Drainage a. Initial Iron-Slag Interface above Level of Taphole b. Initial Iron-Slag Interface at the Taphole c. Initial Iron-Slag Interface below Level of Taphole 5 / 13

5. Interface profile P A > P A j P B + ρ gH > P B j + ρ gh P B = P B j ∴ H > h Drop in pressure occur because of resistance of coke bed and viscous force . L. Shao and H. Saxen.In: Industrial & Engineering Chemistry Research (2013). 6 / 13

6. Downward Tilting of gas-slag interface P A > P A j P B + ρ gH > P B j + ρ gh P B = P B j ∴ H > h In the taphole vicinity interface tilts more because of high flow rate causing large drop in pressure L. Shao and H. Saxen.In : Industrial & Engineering Chemistry Research (2013) 7 / 13

7. Upward Tilting of iron-slag interface P A > P A j P B + ρ gH > P B j + ρ gh P B = P B j ∴ H > h L. Shao and H. Saxen.In: Industrial & Engineering Chemistry Research (2013). 8 / 13 Pressure drop induced by the flow of the more viscous phase (slag) compensates for that induced by the less viscous phase (iron) and its gravitational force .

8. Drainage Performance Slag residual ratio It is the ratio between the initial amount of slag and that remaining in the hearth at the tapping end Modified Slag Residual Ratio= V e/( Vo+ Vprod ) Flow-Out Coefficient Fukutake and Okabe (1976a) conducted extensive experiments and derived dimensionless flow-out coefficient, which correlates with slag residual ratio. l F = 180 2 ℇ 3 (1 − ℇ ) 1 µ V H sl sl φ 2 d p 2 ρ sl g D h ( ) 2 T. Fukutake and K. Okabe. (1976 a ). T. Fukutake and K. Okabe. (1976 b ). 9 / 13

9. Literature review Tanzil , 1984 and Tanzil and Pinczewski, 1987 revealed that iron phase could be drained to levels below the taphole Zulli (1991) to account the inclination of the slag-iron interface and a possible coke-free zone beneath the dead man. l F = 180 2 ℇ 3 (1 − ℇ ) sl g 1 µ V D h d p 2 ρ sl H sl ( ) 1 . 4 Bean (2008) to account for the variation of drainage rate and continuous production of liquid. l F = 180 2 ℇ 3 (1 − ℇ ) d p 2 ρ sl sl g 1 µ V D h H sl + H prod sl ( ) 1 . 4 W. B. U. Tanzil et al.In: Trans of the Iron and Steel Institute of Japan (1984). P. Zulli.In: Doctoral Thesis, University of New South Wales (1991). 10 / 1 3

10. Iron and Slag levels 2 s 3 (1 − s ) sl g 1 µ V D h d p 2 ρ sl H sl Σ Σ 1 . 4 W. B. U. Tanzil et al.In: Trans of the Iron and Steel Institute of Japan (1984). 11 / 1 3 z ir,e z th z sl,e ∆z ir,e ∆z sl,e p th Far - taphole Near - taphole p sl p ir,ft ∆p ir,fl Considering absolute asymptotic limit for the iron level below which no iron can be drained

11. Summary 12 / 13 The behaviour of the blast furnace hearth drainage process is determined by the movement of both the gas-slag and iron-slag interfaces. The characteristic tilting of interfaces are due to viscous pressure gradients in the vicinity of the taphole which are generated by the flow of the highly viscous slag phase. The tap-end levels of iron and slag were tuned using an asymptotic expression Possible to drain iron phase to levels below that of taphole