Effects of post combustion temperature on the wear of the supersonic nozzles in BOF lance tip

Abstract This paper studies the influence of post-combustion on supersonic lance tip nozzles wear for an 80t converter, using CFD (Computational Fluid Dynamics) simulations. These analyses were based on flow profile determination of supersonic jet at minimum and maximum operation flow rates, where it could be verified post-combustion inside the nozzles at lowest flow rates. Additionally, thermal input generated by post-combustion was exported as heat flow in order to serve as a boundary condition in CFD thermal exchange simulations, also considering nozzle internal cooling. With these simulations, it was shown that copper actually reaches its melting point, at which the lowest operating flow allows post-combustion inside the nozzle. The temperature distribution profiles and the high temperatures found were also relevant for a considerable grain growth found in the wear region, according to metallographic analyses. It was thus concluded that wear occurs due to the progressive melting of copper after continuous heats with low oxygen flow rates; post-combustion inside the nozzles is the root cause for this failure.