Patent ID: 8568137
Filing Date: 2013-10-29
Classification: C21D

Abstract:
1. A method for operating a continuous annealing or galvanizing line for a metal strip, the method comprising the following steps: indirectly heating the metal strip by a flame in a direct flame heating section having an upstream zone and a downstream zone; carrying out the heating of the metal strip in the upstream zone by combustion of an atmospheric air and fuel mixture to reach a combustion gas temperature at an end of the upstream zone of between 1250° C. and 1500° C.; carrying out the heating of the metal strip in the downstream zone by combustion of an understoichiometric mixture of air and oxygen-enriched fuel to maintain the combustion gas temperature reached at the end of the upstream zone to an end of the downstream zone; and carrying out an oxygen enrichment of the air and fuel mixture at a rate of between 1% and 15% by volume in comparison with an average rate of oxygen contained in the atmospheric air.