Direct flame preheating section for a continuous metal strip processing line

A direct flame preheating section for a continuous metal strip processing line comprising a connecting zone provided for circulating combustion fumes coming from an active zone equipped with burners to a recuperative zone for preheating the strip by exchange with the combustion fumes, wherein the burners are capable of operating in a no flame mode and wherein the connecting zone comprises an outlet chamber capable of orienting a flow of the combustion fumes so that they flow head-on relative to the strip at an outlet of the active zone and an inlet chamber capable of orienting the flow of the combustion fumes so that they flow head-on relative to the strip at an inlet of the recuperative zone, depending on a direction of flow of the combustion fumes,

• wherein the outlet chamber is arranged at the outlet of the active zone, in the direction of flow of the combustion fumes, and is arranged for drawing off the combustion fumes, wherein the inlet chamber is arranged at the inlet of the recuperative zone and is arranged for injecting the combustion fumes, wherein the connecting zone further comprises two turn chambers each arranged to make the flow of the combustion fumes turn 90 degrees between an inlet opening and an outlet opening, a first turn chamber communicating directly with the outlet chamber and a second turn chamber communicating directly with the inlet chamber, and two connecting tunnels arranged for circulating the combustion fumes, a first connecting tunnel directly connecting the outlet opening of the first turn chamber to an inlet opening of the inlet chamber, and a second connecting tunnel directly connecting an outlet opening of the outlet chamber to an inlet opening of the second turn chamber.