Patent ID: 6514310
Filing Date: 2003-02-04
Classification: C21C,Y02P

Abstract:
Process for injection of a gas, with the aid of a nozzle into a liquid metal bath contained in a metallurgical vessel, the nozzle being installed in the side wall of the vessel and orientated at an angle &agr; with respect to the perpendicular, the downstream end of the nozzle through which the gas escapes in the direction of the liquid metal bath being situated at a distance L from the surface of the liquid metal, the nozzle being fed by the gas through its upstream end at a pressure P1, and being ejected from the nozzle through its downstream end at a pressure P2, the process comprising ejecting the gas from the nozzle into the metallurgical vessel such that the downstream pressure P2 and the pressure P3 in the metallurgical vessel are connected to one another by the relationship:0.9P3&lE;P2&lE;1.1P3, the distance L between the downstream end of the nozzle and the surface of the liquid metal is equal toL(m)=C*{square root over (qe)}Â±0.15(m) where C=4Ï€*P2*M&af;[Î³RTo&it;(1+Î³-12&it;M2)]-1/4*â€ƒ&it;[4.2+1.1*(M2+1-TjTa]&it;Ï jÏ aIn which expression:P2: pressure of the jet at the exit, M: Mach number calculated according to the following formula: M2=2(Î³-1)*[(P1P2)(Î³-1Î³)-1]To: temperature of the gas (K), &ggr;: ratio of Cp/Cv, Cp and Cv being, respectively, the molar thermal capacities at constant pressure or volume, R: ideal gas constant (8.314/molar mass of the gas), qe: mass flow rate (kg/s)=volume flow rate (Sm3/h)*molar mass of the gas/3600/0.0224 (l/mol), Tj: temperature at the exit of the nozzle (K), &rgr;j: density of the jet at the exit of the nozzle (kg/m3), calculated from: P2R*TjTa: temperature of the ambient medium (K), &rgr;a: density of the ambient medium (kg/m3), calculated from: P3R*Tathe injection of the gas being carried out when the temperature of the gases in the metallurgical vessel is greater than 800Â° C.