Efficiency of systems for cooling the tips of oxygen-converter lances

Abstract

Effective cooling is essential to extend the live of oxygen-lance tips [1, 2]. There is an extensive literature on this subject. However, it is very difficult—and sometimes impossible—to compare the efficiency of cooling systems on the basis of the life of oxygen-lance tips, because such systems differ significantly in both external operating conditions (the parameters of the converter, the batch, the blast, and the slag) and internal operating conditions (the parameters of the oxidizing agent, the structure, and the tip material). In the present work, we consider typical tip designs for oxygen lances in (250‐400)-tn converters. The structural parameters and operating conditions of the cooling systems are taken from production data: diameter of oxygen lance’s external tube 426 mm; coolingwater flow rate 450 m 3 /h; 5‐6 injection nozzles. The configuration of the tip components corresponds to the manufacturing documentation. Flow Vision software (OOO Tesis, Russia) is used for hydrodynamic simulation of various tip designs. The mathematical model is based on numerical solution of the Navier‐Stokes equations, the energy equations, and the flow-continuity equations, with the corresponding initial and boundary conditions. The standard k ‐ e model of turbulence is employed. The basic parameters characterizing the hydrodynamic efficiency of the cooling system are as follows: the water speed in the immediate vicinity of the internal surface at the end of the tip, at characteristic points (points 1 ‐ 8 in Fig. 1a); the proportion ϕ c of coolant (relative to the total flow rate) circulating through the central internozzle space of the tip; the loss of water pressure ∆ P t in the tip; and the overall spatial flow pattern of the coolant (the presence and structure of stagnant zones, the flow circulation, etc.).