Process and installation for heating a metallic strip, notably for an annealing

Abstract

The invention pertains to the heating of a metal strip, and relates to equipment for heating a metal strip that comprises a pre-heating housing provided with a device for projecting hot gases towards the strip, a heating housing with regenerative burners, a duct for discharging the gases from the heating housing, a three-way adjustable valve and an adjustment device including a sensor for detecting the setpoint temperature of the metal strip and a member for adjusting the three-way valve so that it can adjust the amount of hot gases fed to the projection device. The invention can be used in equipment for heating narrow strips before annealing the same.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a U.S. National Phase Application of PCT International Application PCT / 2008 / 050874, filed May 20, 2008, which claims priority to French Application FR 0703823, filed May 30, 2007, the contents of both applications being incorporated by reference herein for all purposes.FIELD OF THE INVENTION[0002]The invention relates to a process and an installation for heating a metallic strip to a set temperature needing the presence of a reducing combustion atmosphere (lack of fuel in comparison with stoechiometric quantity).[0003]The invention is described as for its application to heating of a metallic strip in the form of a strap transmitted to an annealing installation, notably for making galvanized steel.BACKGROUND OF THE INVENTION[0004]Various types of annealing installations for straps are already known.[0005]FIG. 1 is a schematic view of a first example of a known installation for preheating a strap to a set temperature app...

AI Technical Summary

Benefits of technology

The patent describes a process and installation for heating a metallic strip, such as a strap, to a specific temperature for annealing. The invention aims to overcome the drawbacks of existing systems, such as inefficient heat exchange and high fuel consumption. The technical effects of the invention include a more efficient heating process and a reduction in the amount of space required for the installation.

Problems solved by technology

The heat exchanges between a surface and a current parallel to this surface are not very efficient, because of the presence of laminar layers.

First, because of the simple circulation of the hot gases in the direction opposite that of the strap in the preheating chamber 102, the heat exchange between the gases and the strip is not efficient, so that the chamber 102 has a very great length and the oven takes up thus much room.

Then, the whole system using open fire burners for forming the reducing combustion atmosphere with the air preheated by the exchanger 122 has a relatively low efficiency, in the order of 50%, so that the fuel consumption is high.

First, the efficiency of the radiant burners used is not high.

Moreover, the whole installation, comprising both chambers and the gas circuit for feeding the chambers for projecting gases onto the strap, contains a protective atmosphere which can be toxic and then does not fulfill the “hygienic” requirements for the combustion, or which is inert and expensive.

At last, as the strap follows a sinuous path inside the preheating chamber, the installation is onerous and prone to failures.

We do not currently know any use of such heating units with regenerative burners in continuous heating installations, for example of the type used for feeding an annealing installation for straps.

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