コールドモデルによる底吹きガスの吹き抜け臨界条件の検討

抄録

Cold model experiments have been made to clarify critical conditions for the occurrence of channelling in bottom blowing. Also, factors controlling the quantity of spitting have been examined by using water and ethyl alcohol as cold bath. Critical bath depth (H_c) at which channelling took place was determined by a weight measuring technique as H^Mes_c and visual observation as H^Obs_c.
Statistical analysis of these data indicates that the critical bath depth[normalized by inner dia. of nozzle (D)] and the quantity of spitting ( W_g) are expressed, respectively, by ;
H^Mes_c / D =5.07(F'_rD)^1/3,
W_g = 10^15.07(F'_rD)^3.83(L₀/ D) ^-6.95(ΔH/D) ^-6.43We^-0.308,
where F'_rD=(ρ_g^v2)/(ρ₁·D·g), v: avarage velocity of gas injected into bath (cm/s), g : acceleration of gravity (cm/s²), ρ_g: density of gas, ρ₁: density of bath (g/cm³), L₀: bath depth (cm), ΔH: distance between the static surface of bath and sponge (cm), We= ρgD·v²>/ σ, and σ is the surface tension of bath (dyn/cm). On the basis of these results, bottom blowing condition suited for an LD converter with bottom blowing is discussed.