EP3397786B1 - Device and method for carrying out controlled oxidation of metal strips in a continuous furnace - Google Patents

Device and method for carrying out controlled oxidation of metal strips in a continuous furnace Download PDF

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Publication number
EP3397786B1
EP3397786B1 EP16822660.3A EP16822660A EP3397786B1 EP 3397786 B1 EP3397786 B1 EP 3397786B1 EP 16822660 A EP16822660 A EP 16822660A EP 3397786 B1 EP3397786 B1 EP 3397786B1
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EP
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Prior art keywords
oxidation
strip
oxidizing gas
chamber
controlled
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EP16822660.3A
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German (de)
French (fr)
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EP3397786A1 (en
Inventor
Pascal THEVENET
Loïc KROTOFF
Stéphane MEHRAIN
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Fives Stein SA
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Fives Stein SA
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • C21D9/561—Continuous furnaces for strip or wire with a controlled atmosphere or vacuum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D9/00—Cooling of furnaces or of charges therein
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/767—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material with forced gas circulation; Reheating thereof
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/56—Continuous furnaces for strip or wire
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0003—Monitoring the temperature or a characteristic of the charge and using it as a controlling value
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0028—Regulation
    • F27D2019/0031—Regulation through control of the flow of the exhaust gases

Definitions

  • the invention relates to a device and a method for producing a controlled oxidation of metal strips, in particular of steel, in continuous line annealing furnaces whose purpose is the production of hot-coated sheets, for example by galvanizing (coating of zinc, zinc and aluminum, zinc and magnesium, or any combination) or aluminizing. It is carried out in the context of a selective oxidation carried out in a controlled atmosphere annealing furnace, or of a total oxidation in an oxidizing annealing furnace, generally with a direct flame.
  • the heterogeneity in the width and the strip length of the oxygen content of the oxidizing gas, its temperature and its flow rate at the surface of the strip creates a different oxidation on the tape. This is particularly the case in oxidation zones where the extraction of the oxidizing gas from the oxidation chamber is not controlled.
  • the document EP2458022 describes the oxidation of strips by injection on the strip, through a nozzle system, a mixture of air and nitrogen, or a mixture of oxygen and nitrogen, in a radiant tube furnace or direct fire, the oven working in a substantially non-oxidizing manner.
  • the nozzle system is designed to evenly distribute the oxidant gas across the bandwidth. It does not make it possible to vary the distribution of the oxidizing gas so as to correct an oxidation heterogeneity of the band present at the inlet of the system by performing a greater oxidation in the places where it is lower upstream of the system.
  • the document JP 003342645 discloses a controlled oxidation chamber of bands for oxidation by means of an oxidizing gas, the chamber has blowing means and at least one suction port between which circulates the oxidizing gas in a controlled manner.
  • FRA2920439 discloses a method of continuous galvanizing annealing of steel strips comprising a section equipped with modified radiant tubes; the oxidation is carried out by an oxidizing medium injected via said tubes, which comprises a step of measuring the dew point of the oxidizing medium in the sections of the furnace where the modified tubes are installed and a step of regulating the flow rate of oxidizing medium in closed loop with dew point measurement.
  • the known oxidation chambers have an extraction of the oxidizing gas at each end. No means are placed inside the chambers so as to achieve local extraction of the oxidizing gas and thus limit interference between the injected gas and the gas having been in contact with the strip.
  • the invention makes it possible to overcome these problems by making it possible to control the oxidation of the strip in the longitudinal and transverse directions of the strip. It can be implemented indifferently in direct oxidizing fire furnaces preferentially or preferably non-oxidizing or in controlled atmosphere furnaces.
  • the invention consists in producing an injection of air or fumes, or an air / smoke mixture, on the strip in a so-called chamber.
  • Controlled oxidation in which the strip is at a temperature adapted to undergo the desired oxidation.
  • the controlled oxidation chamber has means for controlling the flow rate, the temperature, and the injection kinetics on the injected gas band according to the need and to ensure the evacuation of the chamber after its reaction with the band.
  • This solution can be applied over the entire width of the strip or only on a transverse or longitudinal part of the strip requiring additional oxidation.
  • the injection of air makes it possible to obtain a high oxygen content at a lower cost, compared to the solutions according to the state of the art. This makes it possible to minimize the dimensions of the injection circuits and to obtain a greater oxidation reactivity.
  • the injection of fumes, or an air / fumes mixture makes it possible to obtain a controlled oxygen level, lower than 21%, which reduces the rate of oxidation compared to the injection of air but gives a greater adjustment fineness and thus greater oxidation accuracy than using pure air.
  • the invention is implemented downstream of a first section in which a "coarse" oxidation is performed so as to obtain substantially the required thickness of oxides.
  • coarse oxidation is meant oxidation without fine control thereof over the bandwidth.
  • the second downstream section in which is implemented the invention allows to finely adjust the thickness of oxide on the bandwidth so that it is homogeneous.
  • the first coarse oxidation section may be a selective oxidation section in a controlled atmosphere annealing furnace, for example in an RTF furnace (Radiant Tube Furnace).
  • the controlled oxidation chamber according to the invention implanted downstream, is for example placed between a heating section and a section maintaining the temperature of the strip, or in a connecting tunnel between two sections of the continuous line, for example in the tunnel connecting the RTF furnace and the cooling section of the strip.
  • the first coarse oxidation section may also be a direct flame heating section, for example a NOF (Non Oxidizing Furnace) or DFF (Direct Firing Furnace) section.
  • the controlled oxidation chamber according to the invention is for example placed at the outlet of the NOF or DFF section, in the running direction of the strip, or in the connection tunnel between the NOF or DFF section and the radiant tube furnace. , in the radiant tube furnace or downstream thereof.
  • the device according to the invention is composed of a multi-part transverse and longitudinal blowing system over the independently controlled width and strip length for controlling the desired oxide value over the bandwidth.
  • a symmetrical suction suction system allows the return of the injected gas after its reaction with the surface of the strip by limiting the interference between the gas to be injected and the gas that has been in contact with the strip.
  • the distance between the injection system and the strip is determined according to the geometry and the distribution of the blowing orifices and the kinematics of the jets so as to cover the surface of the strip with little overlap of the jets on it.
  • the injection system and the suction system can be placed at the same distance from the band, or can be shifted, the suction being for example placed at a greater distance from the band.
  • the suction and blowing parts of the zone in question are controlled simultaneously, which makes it possible for the injected gas flow to escape after a residence time equivalent to the defined distance and not to diffuse laterally towards other zones of the strip. and therefore cause unwanted oxidation on other areas of the band.
  • the temperature level of the oxidizing gas at the outlet of the injection system is advantageously close to that of the band in order to limit thermal stresses in the band which could cause deformation of it.
  • a hot gas also increases the reactivity of the oxidation compared to a cold gas.
  • the transverse and longitudinal distribution of the oxidation of the strip upstream of the controlled oxidation chamber according to the invention is determined so as to identify the places where the controlled oxidation must be carried out and with what importance.
  • This analysis of the surface of the strip upstream of the device according to the invention can be carried out by sensors measuring the thickness of the oxidation over the width of the strip or by an image analysis of the strip.
  • the controlled oxidation chamber of metal strips in an annealing furnace of a continuous line of production of hot-coated strips, for example by galvanizing, the oxidation chamber for the oxidation of the metal strips by means of a gas oxidant injected on at least one of the faces of a strip is characterized in that it comprises oxidation portions extending over its width and / or length, each portion comprising at least one blowing orifice and at least one suction port between which an oxidizing gas circulates, each portion being separately controllable to adjust the oxidation induced on the strip over the width and length of the oxidation chamber.
  • the oxidizing gas may be injected onto the strip in a direction substantially perpendicular to the strip by means of blowing orifices and in that the oxidizing gas then circulates in the chamber towards suction ports in a direction substantially parallel to the direction of travel of the strip or in a direction having a component perpendicular to the running direction of the strip.
  • Suction orifices placed on the sides of a suction portion relative to the running direction of the strip complementary to one or more suction orifices placed at the end of the suction portion in the running direction of the strip leads to a flow of the oxidizing gas in the chamber in a direction having a component perpendicular to the running direction of the strip.
  • the combination of these holes suction allows to precisely define the periphery of each oxidation portion.
  • the controlled oxidation chamber may be placed downstream, in the running direction of the strip, of a section in which the strip undergoes a first oxidation.
  • the oxidizing gas used may be air, smoke, or a mixture of air and smoke.
  • the fumes advantageously come from at least one burner placed close to the controlled oxidation chamber, for example open flame burners of a NOF section or radiant tube burners of an RTF furnace.
  • the fumes collected near the controlled oxidation chamber, for example in a flue gas plenum, are thus injected into the controlled oxidation chamber.
  • the controlled oxidation chamber comprises at least one oxidation sensor located upstream and / or downstream of the oxidation portion, the information coming from the oxidation sensor being integrated into the calculation of the outgoing oxidizing gas flow. the blowing orifice of the oxidation portion.
  • the invention also relates to a method of controlled oxidation of metal strips implemented in a controlled oxidation chamber mentioned above, by means of an oxidizing gas injected on at least one of the faces of the strip, said gas oxidant being air or combustion fumes, or a mixture of air and combustion fumes.
  • the characteristics of the oxidizing gas and / or the kinetics of injection and suction of the oxidizing gas in the oxidation portions are advantageously controlled to adjust the oxidation induced on the strip over the width and the length of the oxidation chamber.
  • an oxidation portion is controlled by the choice of the blowing orifices and the suction orifices in use in said portion.
  • several series of blowholes and several series of suction ports are provided. We then perform a choice among these series of orifices depending on the desired distance between the blowing zone and the suction zone, that is to say according to the desired oxidation.
  • the residence time of the oxidizing gas in the controlled oxidation chamber may be adjusted by the portion along the length of said portion in the running direction of the strip.
  • FIGS. 1 to 4 show in schematic views examples of architecture of oxidation chambers according to the invention in which the band flows in the direction indicated by the arrow 16, in a zone of oxidizing or non-oxidizing furnace.
  • FIGS. 1 to 4 show schematically in front view an example of a wall 2 of a controlled oxidation chamber 1 according to the invention, as seen by one side of the strip.
  • the walls of the oxidation chamber here consist of elementary modules 3 juxtaposed of rectangular shape. It may for example be brick refractory material. However, this exemplary embodiment is only illustrative, other embodiments may be used.
  • the walls of the oxidation chamber may be in one module. They can be lined with refractory fiber, and possibly covered with a stainless steel sheet.
  • certain elementary modules 3 comprise circular or rectangular orifices 4, 5 through which the gas is injected onto the strip or discharged from the oxidation chamber.
  • the number of injection orifices 4 per elementary module and the unit section of these orifices are chosen so as to cover the entire bandwidth with unit gas jets whose shape and kinematics allow to cover a unitary band surface with a speed adapted to ensure the oxidation of the band.
  • suction orifices 5 are placed above blowing orifices 4, but this example is not restrictive, the suction orifices being able to be placed below the injection orifices.
  • the band flows as shown from bottom to top, the flow of the injected gas is therefore in the direction of flow of the strip. If the band flows from top to bottom, the flow of the injected gas is therefore in the opposite direction of the flow of the band.
  • these figures illustrate a vertical chamber. Obviously, it could also be a horizontal chamber, with a horizontal scroll of the strip, or an inclined chamber, for which the position of the orifices would then be defined more generally in the direction of travel of the strip.
  • blowing holes 4 are located in two successive rows of unit modules 3.
  • the blowing ports are thus aligned on two lines 6, 7 parallel to the bandwidth.
  • the position of the orifices is shifted to the second row 7 relative to the first row 6, so as to obtain a greater overlap of the surface of the strip over its width.
  • the suction orifices 5 have a similar distribution and are distributed in two rows 8 and 9.
  • the distribution of the suction orifices 5 is symmetrical to that of the blowing orifices 4 along an axis of transverse symmetry passing halfway between the
  • the distance between the blowing zone and the suction zone, in the running direction of the strip, is a function of the maximum speed of movement of the strip and the kinematics of the gas. oxidant blown on the tape. It corresponds here to three rows of unitary modules.
  • blow holes 4 and suction ports 5 in operation and their location are adjusted according to the locations on the surface of the strip where it is necessary to perform additional oxidation of the strip.
  • the suction ports 5 in operation are naturally in alignment with the blowing holes 4, in the running direction of the strip.
  • the oxidizing gas flow rate can be adjusted by line 6, 7 of blowing ports, by set of blow holes, or individually by blowing orifice 4, so as to adjust for each orifice 4 or set of orifices kinematic jets of oxidizing gas and their effect on the band.
  • the oxidizing gas is a mixture of air and smoke
  • FIG 2 we can see represented diagrammatically an example of realization similar to that represented in Fig. 1 but with openings of blow and suction of rectangular section.
  • a unit portion 17 defined by a blowing orifice and a suction orifice is shown in this figure.
  • the figure 3 schematically represents by way of example the architecture of an oxidation chamber according to the invention having 8 lines 6 to 13 orifices per strip face.
  • This oxidation chamber is longer than those of Figures 1 and 2 is particularly suitable for high speeds of tape travel.
  • the longer length of the oxidation chamber makes it possible to perform the oxidation with a slower kinematics which may be advantageous for certain steel grades.
  • this chamber can thus have two successive oxidation zones by blow / suction, the lines of orifices 6, 7, 10 and 11 ensuring the blowing and the lines 8, 9, 12 and 13 the suction. It is for example possible to dedicate each to a gas of different nature, or to blow the same gas with two different injection kinematics.
  • This chamber can also be operated using only the lines of orifices 6 and 7 for blowing the oxidizing gas and lines 8 to 13 in suction.
  • the suction ports used will be those of the lines 8 and 9, or those of the lines 10 and 11 or those of the lines 12 and 13, the lines 8 and 9 leading to the shortest exchange length and lines 12 and 13 to the longest exchange length.
  • the figure 4 schematically represents by way of example the architecture of an oxidation chamber according to the invention in the same principle as that of the figure 3 but advantageously having transverse aspirations 14 arranged successively according to the width of the oven.
  • the presence of these transverse aspirations 14 makes it possible to delimit precisely on the bandwidth, and the length of the oxidation chamber, zones in which the oxidation can be controlled separately.
  • the device according to the invention can thus be composed of a longitudinal blowing system in several independently controlled parts and of a suction system alternately disposed at blowing and disposed at an advantageous distance allowing the control of the oxide value. desired on the tape.
  • the suction and blowing parts of the zone in question are controlled simultaneously, which allows the flow of injected air to escape after a residence time equivalent to the defined distance and not to diffuse laterally to other zones of the strip. , and thus cause unwanted oxidation on other areas of the band
  • the figure 5 schematically represents a sectional view of an oxidation chamber 1 at the level of blowing orifices 4, according to an exemplary embodiment of the invention.
  • the blowing holes do not exceed unit modules 3 in the direction of the strip 15.
  • the figure 6 schematically represents a sectional view of an oxidation chamber 1 at the level of blowing orifices 4, according to another embodiment of the invention in which the blowing orifices protrude from the unitary modules 3 in the direction of the strip 15 .
  • the suction ports are not shown. They may not exceed unit modules 3 in the direction of the band 15 or exceed said modules.
  • the blowing and suction orifices may not exceed unitary modules 3 in the direction of the strip 15, the blowing orifices may not exceed while the suction orifices exceed , and the blowing holes may protrude while the suction ports do not protrude.
  • the distance between the strip and the end of the blowing and suction ports is particularly related to the flow rate and kinematics of the oxidizing gas jets.
  • the minimum air injection flow rate in the oxidation zone is very low (for example 10 Nm 3 / h of air for a flow of the oxidizing gas over a length of one meter, measured between blowing and suction and / or length, in the longitudinal direction of travel of the strip, corresponding to the desired oxidation portion, said length giving an oxide thickness of 70 nm on a strip of 1500 mm wide scrolling at 100m / min at a temperature of 650 ° C.)
  • the control of the oxidation can be advantageously done by the opening / closing of one or more oxidation zones (blowing / suction) and thus of varying the overall flow rate for vary the residence time under oxidizing gas of the strip and thus vary the oxide thickness.
  • the control of the oxidation can be advantageously done by the opening / closing of one or more oxidation zones (blowing / suction) and thus of varying the overall flow rate for vary the residence time under oxidizing gas of the strip and thus vary the oxide thickness.
  • it can
  • This operation can be performed over the entire width of the strip or only a part, thus giving great flexibility in the management of the atmosphere in contact with the strip while keeping at least the critical injection speeds on the strip in the desired oxidation zone and isolating the other zones by injection of a neutral gas such as nitrogen for example .
  • This operating mode makes it possible to dispense with the speed of travel of the strip in the control of the oxide thickness.
  • the device according to the invention is placed downstream of an oxidation section without precise control of the oxidation over the bandwidth. This allows, for example, to achieve quickly, that is to say, over a limited furnace length, most of the oxide layer referred to.
  • the device according to the invention then makes it possible locally to carry out additional oxidation, for example to obtain a homogeneous oxide thickness over the bandwidth or to reinforce it locally.
  • the oxidation section without precise control of the oxidation over the bandwidth may also make it possible to produce a layer whose oxides will have a given morphology or composition, different from the surface layer which will then be produced by the device according to the invention. invention.
  • the oxidation section 100 without precise control of the oxidation on the bandwidth is a portion of a preheating furnace 110 of the direct flame band.
  • this oven comprises a zone 120 for preheating the strip by exhausting the flue gas followed by a heating zone 130 equipped with direct flame burners.
  • the first 15 pairs of burners (over 13 m of oven length) operate in air defect so as to avoid oxidation of the band.
  • the last 3 pairs of burners (over 4.2 m of oven length) delimit the section 100 in which the burners operate with a large excess of air to obtain a significant oxidation of the band.
  • the device 1 according to the invention placed downstream of this oxidizing zone then makes it possible to finely adjust the oxidation on the bandwidth.
  • the width of 1500 mm band is running at a nominal speed of 100 m / min.
  • the chamber 1 has a length of 475 mm in the direction of travel of the strip.
  • the blowing zone has 55 orifices arranged on two transverse lines 80 mm apart.
  • the suction zone has 55 orifices arranged on two transverse lines 80 mm apart.
  • the distance between the nearest blow and suction lines is 315 mm.
  • the blow holes are located 100 mm from the strip every 58 mm depending on the bandwidth. Their injection diameter is 25 mm.
  • the suction ports are located 100 mm from the belt every 58 mm depending on the bandwidth. Their suction diameter is 25 mm.
  • the oxidizing gas is air. It is injected on the belt at a nominal speed of 3 m / s. The injection speed is modulated by injector, or injector assembly, between 0 and 5 m / s depending on the amount of oxidation sought on the surface of the band concerned.
  • the band is at 650 ° C when it enters the oxidation chamber.
  • the oxidizing gas is injected at a temperature of 650 ° C.

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Description

Domaine d'applicationApplication domain

L'invention concerne un dispositif et un procédé pour réaliser une oxydation contrôlée de bandes métalliques, notamment d'acier, dans les fours de recuit de lignes continues dont la destination est la production de tôles revêtues à chaud, par exemple par galvanisation (revêtement de zinc, de zinc et d'aluminium, de zinc et de magnésium, ou tout autre combinaison) ou aluminage. Elle est mise en oeuvre dans le cadre d'une oxydation sélective réalisée dans un four de recuit sous atmosphère contrôlée, ou d'une oxydation totale dans un four de recuit oxydant, généralement à flamme directe.The invention relates to a device and a method for producing a controlled oxidation of metal strips, in particular of steel, in continuous line annealing furnaces whose purpose is the production of hot-coated sheets, for example by galvanizing (coating of zinc, zinc and aluminum, zinc and magnesium, or any combination) or aluminizing. It is carried out in the context of a selective oxidation carried out in a controlled atmosphere annealing furnace, or of a total oxidation in an oxidizing annealing furnace, generally with a direct flame.

Problème technique auquel l'invention apporte une solutionTechnical problem to which the invention provides a solution

Dans une section d'oxydation sélective ou totale, l'hétérogénéité sur la largeur et la longueur de bande de la teneur en oxygène du gaz oxydant, de sa température et de sa vitesse d'écoulement à la surface de la bande crée une oxydation différente sur la bande. Cela est notamment le cas dans les zones d'oxydation où l'extraction du gaz oxydant de la chambre d'oxydation n'est pas contrôlée.In a selective or total oxidation section, the heterogeneity in the width and the strip length of the oxygen content of the oxidizing gas, its temperature and its flow rate at the surface of the strip creates a different oxidation on the tape. This is particularly the case in oxidation zones where the extraction of the oxidizing gas from the oxidation chamber is not controlled.

Etat de l'artState of the art

La production de certains types d'aciers pose un problème d'adhésion du revêtement pour des nuances contenant des teneurs élevées en éléments d'alliage tels que le manganèse, le silicium ou l'aluminium, par création d'oxydes en surface de la bande pénalisant la mouillabilité du substrat.The production of certain types of steels poses a coating adhesion problem for grades containing high levels of alloying elements such as manganese, silicon or aluminum, by creating oxides on the surface of the strip penalizing the wettability of the substrate.

Plusieurs procédés existent pour améliorer cette mouillabilité, notamment :

  • Création d'un oxyde de fer en surface dite oxydation totale, dans un four oxydant à flamme directe formant une barrière à la remontée de ces éléments et à leur oxydation en surface, suivie d'une réduction de ces oxydes avant le revêtement de la bande.
  • Oxydation en profondeur de ces éléments empêchant leur remontée en surface, dans un four à atmosphère contrôlée, par injection d'oxygène ou d'eau dite oxydation sélective, suivie d'une réduction des oxydes présents en surface avant le revêtement de la bande.
Several methods exist to improve this wettability, in particular:
  • Creation of an iron oxide on the surface called total oxidation, in a direct flame oxidizing furnace forming a barrier to the rise of these elements and their surface oxidation, followed by a reduction of these oxides before coating the strip.
  • Deep oxidation of these elements preventing their rise to the surface, in a controlled atmosphere furnace, by injection of oxygen or water called selective oxidation, followed by a reduction of oxides present on the surface before coating the strip.

Le document EP2458022 décrit l'oxydation de bandes par injection sur la bande, à travers un système de buse, d'un mélange d'air et d'azote, ou d'un mélange d'oxygène et d'azote, dans un four à tubes radiants ou à feux direct, le four travaillant d'une manière essentiellement non-oxydante. Le système de buse est conçu de manière à distribuer de manière homogène le gaz oxydant sur la largeur de bande. Il ne permet pas de faire varier la distribution du gaz oxydant de sorte de corriger une hétérogénéité d'oxydation de la bande présente en entrée du système en réalisant une oxydation plus importante aux endroits où celle-ci est plus faible en amont du système.The document EP2458022 describes the oxidation of strips by injection on the strip, through a nozzle system, a mixture of air and nitrogen, or a mixture of oxygen and nitrogen, in a radiant tube furnace or direct fire, the oven working in a substantially non-oxidizing manner. The nozzle system is designed to evenly distribute the oxidant gas across the bandwidth. It does not make it possible to vary the distribution of the oxidizing gas so as to correct an oxidation heterogeneity of the band present at the inlet of the system by performing a greater oxidation in the places where it is lower upstream of the system.

Le document JP 003342645 divulgue une chambre d'oxydation contrôlée de bandes permettant l'oxydation au moyen d'un gaz oxydant, la chambre dispose de moyens de soufflage et au moins un orifice d'aspiration entre lesquels circule le gaz oxydant de façon contrôlée. De plus, FRA2920439 divulgue un procédé de recuit de galvanisation en continu de bandes d'acier comprenant une section équipée de tubes radiants modifiés; l'oxydation est effectuée par un médium oxydant injecté par l'intermédiaire desdites tubes ce qu'il comprend une étape de mesure du point de rosée du médium oxydant dans les sections du four où sont installés les tubes modifiés et une étape de régulation du débit de médium oxydant en boucle fermée avec la mesure de point de rosée. Les chambres d'oxydation connues disposent d'une extraction du gaz oxydant à chaque extrémité. Aucun moyen n'est placé à l'intérieur des chambres de sorte de réaliser localement l'extraction du gaz oxydant et limiter ainsi les interférences entre le gaz injecté et le gaz ayant été en contact avec la bande.The document JP 003342645 discloses a controlled oxidation chamber of bands for oxidation by means of an oxidizing gas, the chamber has blowing means and at least one suction port between which circulates the oxidizing gas in a controlled manner. In addition, FRA2920439 discloses a method of continuous galvanizing annealing of steel strips comprising a section equipped with modified radiant tubes; the oxidation is carried out by an oxidizing medium injected via said tubes, which comprises a step of measuring the dew point of the oxidizing medium in the sections of the furnace where the modified tubes are installed and a step of regulating the flow rate of oxidizing medium in closed loop with dew point measurement. The known oxidation chambers have an extraction of the oxidizing gas at each end. No means are placed inside the chambers so as to achieve local extraction of the oxidizing gas and thus limit interference between the injected gas and the gas having been in contact with the strip.

L'invention permet de pallier ces problèmes en permettant de maîtriser l'oxydation de la bande dans les sens longitudinal et transversal de la bande. Elle peut être mise en œuvre indifféremment dans des fours à feux direct oxydant préférentiellement ou préférentiellement non-oxydant ou dans des fours à atmosphère contrôlée.The invention makes it possible to overcome these problems by making it possible to control the oxidation of the strip in the longitudinal and transverse directions of the strip. It can be implemented indifferently in direct oxidizing fire furnaces preferentially or preferably non-oxidizing or in controlled atmosphere furnaces.

Description de l'inventionDescription of the invention

L'invention consiste à réaliser une injection d'air ou de fumées, ou d'un mélange air/fumées, sur la bande dans une chambre dite « d'oxydation contrôlée » dans laquelle la bande est à une température adaptée pour subir l'oxydation recherchée.La chambre d'oxydation contrôlée dispose de moyens permettant de contrôler le débit, la température, et la cinétique d'injection sur la bande du gaz injecté en fonction du besoin et d'en assurer l'évacuation de la chambre après sa réaction avec la bande.The invention consists in producing an injection of air or fumes, or an air / smoke mixture, on the strip in a so-called chamber. "Controlled oxidation" in which the strip is at a temperature adapted to undergo the desired oxidation.The controlled oxidation chamber has means for controlling the flow rate, the temperature, and the injection kinetics on the injected gas band according to the need and to ensure the evacuation of the chamber after its reaction with the band.

Cette solution peut être appliquée sur toute la largeur de la bande ou seulement sur une partie transversale ou longitudinale de la bande nécessitant une oxydation supplémentaire.This solution can be applied over the entire width of the strip or only on a transverse or longitudinal part of the strip requiring additional oxidation.

Du fait de sa teneur de 21 % en oxygène, l'injection d'air permet d'obtenir un taux d'oxygène élevé pour un coût moindre, comparé aux solutions selon l'état de la technique. Cela permet de minimiser les dimensions des circuits d'injection et d'obtenir une réactivité d'oxydation plus importante.Because of its 21% oxygen content, the injection of air makes it possible to obtain a high oxygen content at a lower cost, compared to the solutions according to the state of the art. This makes it possible to minimize the dimensions of the injection circuits and to obtain a greater oxidation reactivity.

L'injection de fumées, ou d'un mélange air/fumées, permet d'obtenir un taux d'oxygène contrôlé, inférieur à 21%, qui réduit la vitesse d'oxydation par rapport à l'injection d'air mais donne une finesse de réglage plus importante et donc une précision d'oxydation plus importante que par l'utilisation d'air pur.The injection of fumes, or an air / fumes mixture, makes it possible to obtain a controlled oxygen level, lower than 21%, which reduces the rate of oxidation compared to the injection of air but gives a greater adjustment fineness and thus greater oxidation accuracy than using pure air.

Le choix d'une solution ou l'autre peut être défini en fonction du besoin et représente de toute évidence une économie par rapport à l'utilisation d'un mélange d'oxygène ou d'azote pris séparément.The choice of one solution or the other can be defined according to need and obviously represents a saving in relation to the use of a mixture of oxygen or nitrogen taken separately.

L'injection du gaz oxydant à vitesse contrôlée permet d'améliorer le procédé car il est admis qu'une vitesse critique minimum du gaz oxydant à la surface de la tôle augmente fortement la vitesse d'oxydation.The injection of the oxidizing gas at a controlled speed makes it possible to improve the process since it is assumed that a minimum critical speed of the oxidizing gas at the surface of the sheet greatly increases the rate of oxidation.

Avantageusement, l'invention est mise en œuvre en aval d'une première section dans laquelle une oxydation « grossière » est réalisée de sorte d'obtenir sensiblement l'épaisseur d'oxydes requise. Par oxydation grossière, on entend une oxydation sans contrôle fin de celle-ci sur la largeur de bande. Ainsi, la seconde section placée en aval dans laquelle est mise en œuvre l'invention permet d'ajuster finement l'épaisseur d'oxyde sur la largeur de bande de sorte que celle-ci soit homogène. La première section d'oxydation grossière peut être une section d'oxydation sélective dans un four de recuit sous atmosphère contrôlée, par exemple dans un four RTF (four à tubes radiants ou Radiant Tube Furnace). La chambre d'oxydation contrôlée selon l'invention, implantée en aval, est par exemple placée entre une section de chauffage et une section de maintien à température de la bande, ou dans un tunnel de liaison entre deux sections de la ligne continue, par exemple dans le tunnel de liaison entre le four RTF et la section de refroidissement de la bande. La première section d'oxydation grossière peut également être une section de chauffage à flamme directe, par exemple une section NOF (Non Oxydazing Furnace) ou DFF (Direct Firing Furnace). La chambre d'oxydation contrôlée selon l'invention est par exemple placée en sortie de la section NOF ou DFF, dans le sens de défilement de la bande, ou dans le tunnel de liaison entre la section NOF ou DFF et le four à tube radiants, dans le four à tube radiants ou en aval de celui-ci.Advantageously, the invention is implemented downstream of a first section in which a "coarse" oxidation is performed so as to obtain substantially the required thickness of oxides. By coarse oxidation is meant oxidation without fine control thereof over the bandwidth. Thus, the second downstream section in which is implemented the invention allows to finely adjust the thickness of oxide on the bandwidth so that it is homogeneous. The first coarse oxidation section may be a selective oxidation section in a controlled atmosphere annealing furnace, for example in an RTF furnace (Radiant Tube Furnace). The controlled oxidation chamber according to the invention, implanted downstream, is for example placed between a heating section and a section maintaining the temperature of the strip, or in a connecting tunnel between two sections of the continuous line, for example in the tunnel connecting the RTF furnace and the cooling section of the strip. The first coarse oxidation section may also be a direct flame heating section, for example a NOF (Non Oxidizing Furnace) or DFF (Direct Firing Furnace) section. The controlled oxidation chamber according to the invention is for example placed at the outlet of the NOF or DFF section, in the running direction of the strip, or in the connection tunnel between the NOF or DFF section and the radiant tube furnace. , in the radiant tube furnace or downstream thereof.

Le dispositif selon l'invention est composé d'un système de soufflage transversal et longitudinal en plusieurs parties sur la largeur et la longueur de bande contrôlées indépendamment permettant le contrôle de la valeur d'oxyde souhaité sur la largeur de bande. Un système d'aspiration symétrique au soufflage permet la reprise du gaz injecté après sa réaction avec la surface de la bande en limitant les interférences entre le gaz injecter et le gaz ayant été en contact avec la bande.The device according to the invention is composed of a multi-part transverse and longitudinal blowing system over the independently controlled width and strip length for controlling the desired oxide value over the bandwidth. A symmetrical suction suction system allows the return of the injected gas after its reaction with the surface of the strip by limiting the interference between the gas to be injected and the gas that has been in contact with the strip.

La distance entre le système d'injection et la bande est déterminé selon la géométrie et la répartition des orifices de soufflage et la cinématique des jets de sorte de couvrir la surface de la bande avec peu de recouvrement des jets sur celle-ci. Le système d'injection et le système d'aspiration peuvent être placés à la même distance de la bande, ou peuvent être décalés, l'aspiration étant par exemple placée à une distance plus importante de la bande.The distance between the injection system and the strip is determined according to the geometry and the distribution of the blowing orifices and the kinematics of the jets so as to cover the surface of the strip with little overlap of the jets on it. The injection system and the suction system can be placed at the same distance from the band, or can be shifted, the suction being for example placed at a greater distance from the band.

Les parties aspiration et soufflage de la zone considérée sont commandées simultanément ce qui permet au débit de gaz injecté de s'évacuer après un temps de séjour équivalent à la distance définie et de ne pas se diffuser latéralement vers d'autres zones de la bande, et donc provoquer d'oxydation non désirée sur d'autres zones de la bande.The suction and blowing parts of the zone in question are controlled simultaneously, which makes it possible for the injected gas flow to escape after a residence time equivalent to the defined distance and not to diffuse laterally towards other zones of the strip. and therefore cause unwanted oxidation on other areas of the band.

Le niveau de température du gaz oxydant en sortie du système d'injection est avantageusement proche de celui de la bande afin de limiter les contraintes thermiques dans la bande qui pourraient provoquer une déformation de celle-ci. Un gaz chaud augmente également la réactivité de l'oxydation en comparaison à un gaz froid.The temperature level of the oxidizing gas at the outlet of the injection system is advantageously close to that of the band in order to limit thermal stresses in the band which could cause deformation of it. A hot gas also increases the reactivity of the oxidation compared to a cold gas.

Avantageusement, la répartition transversale et longitudinale de l'oxydation de la bande en amont de la chambre d'oxydation contrôlée selon l'invention est déterminée de sorte d'identifier les endroits où l'oxydation contrôlée doit être réalisée et avec quelle importance. Cette analyse de la surface de la bande en amont du dispositif selon l'invention peut être réalisée par des capteurs mesurant l'épaisseur de l'oxydation sur la largeur de la bande ou par une analyse d'images de la bande.Advantageously, the transverse and longitudinal distribution of the oxidation of the strip upstream of the controlled oxidation chamber according to the invention is determined so as to identify the places where the controlled oxidation must be carried out and with what importance. This analysis of the surface of the strip upstream of the device according to the invention can be carried out by sensors measuring the thickness of the oxidation over the width of the strip or by an image analysis of the strip.

La chambre d'oxydation contrôlée de bandes métalliques dans un four de recuit d'une ligne continue de production de bandes revêtues à chaud, par exemple par galvanisation, la chambre d'oxydation permettant l'oxydation des bandes métalliques au moyen d'un gaz oxydant injecté sur au moins l'une des faces d'une bande est caractérisée en ce qu'elle comprend des portions d'oxydation s'étendant sur sa largeur et/ou sa longueur, chaque portion comprenant au moins un orifice de soufflage et au moins un orifice d'aspiration entre lesquels circule un gaz oxydant, chaque portion pouvant être contrôlée de manière distincte pour ajuster l'oxydation induite sur la bande sur la largeur et la longueur de la chambre d'oxydation.The controlled oxidation chamber of metal strips in an annealing furnace of a continuous line of production of hot-coated strips, for example by galvanizing, the oxidation chamber for the oxidation of the metal strips by means of a gas oxidant injected on at least one of the faces of a strip is characterized in that it comprises oxidation portions extending over its width and / or length, each portion comprising at least one blowing orifice and at least one suction port between which an oxidizing gas circulates, each portion being separately controllable to adjust the oxidation induced on the strip over the width and length of the oxidation chamber.

Le gaz oxydant peut être injecté sur la bande selon une direction sensiblement perpendiculaire à la bande au moyen d'orifices de soufflage et en ce qu'ensuite le gaz oxydant circule dans la chambre vers des orifices d'aspiration selon une direction sensiblement parallèle à la direction de défilement de la bande ou selon une direction ayant une composante perpendiculaire à la direction de défilement de la bande. Des orifices d'aspiration placés sur les côtés d'une portion d'aspiration par rapport à la direction de défilement de la bande venant en complément d'un ou plusieurs orifices d'aspiration placés à l'extrémité de la portion d'aspiration dans la direction de défilement de la bande conduisent à un écoulement du gaz oxydant dans la chambre selon une direction ayant une composante perpendiculaire à la direction de défilement de la bande. La combinaison de ces orifices d'aspiration permet de définir précisément la périphérie de chaque portion d'oxydation.The oxidizing gas may be injected onto the strip in a direction substantially perpendicular to the strip by means of blowing orifices and in that the oxidizing gas then circulates in the chamber towards suction ports in a direction substantially parallel to the direction of travel of the strip or in a direction having a component perpendicular to the running direction of the strip. Suction orifices placed on the sides of a suction portion relative to the running direction of the strip complementary to one or more suction orifices placed at the end of the suction portion in the running direction of the strip leads to a flow of the oxidizing gas in the chamber in a direction having a component perpendicular to the running direction of the strip. The combination of these holes suction allows to precisely define the periphery of each oxidation portion.

La chambre d'oxydation contrôlée peut être placée en aval, dans le sens de défilement de la bande, d'une section dans laquelle la bande subit une première oxydation.The controlled oxidation chamber may be placed downstream, in the running direction of the strip, of a section in which the strip undergoes a first oxidation.

Le gaz oxydant utilisé peut être de l'air, des fumées, ou un mélange d'air et de fumées. Les fumées proviennent avantageusement d'au moins un brûleur placé à proximité de la chambre d'oxydation contrôlée, par exemple de brûleurs à flamme nue d'une section NOF ou de brûleurs à tube radiant d'un four RTF. Les fumées captées à proximité de la chambre d'oxydation contrôlée, par exemple dans une plénum d'évacuation des fumées, sont ainsi injectées dans la chambre d'oxydation contrôlée.The oxidizing gas used may be air, smoke, or a mixture of air and smoke. The fumes advantageously come from at least one burner placed close to the controlled oxidation chamber, for example open flame burners of a NOF section or radiant tube burners of an RTF furnace. The fumes collected near the controlled oxidation chamber, for example in a flue gas plenum, are thus injected into the controlled oxidation chamber.

Avantageusement la chambre d'oxydation contrôlée comprend au moins un capteur d'oxydation situé en amont et/ou en aval de la portion d'oxydation, l'information issue du capteur d'oxydation étant intégrée dans le calcul du débit de gaz oxydant sortant de l'orifice de soufflage de la portion d'oxydation.Advantageously, the controlled oxidation chamber comprises at least one oxidation sensor located upstream and / or downstream of the oxidation portion, the information coming from the oxidation sensor being integrated into the calculation of the outgoing oxidizing gas flow. the blowing orifice of the oxidation portion.

L'invention concerne également un procédé d'oxydation contrôlée de bandes métalliques mis en œuvre dans une chambre d'oxydation contrôlée évoquée plus haut, au moyen d'un gaz oxydant injecté sur au moins l'une des faces de la bande, ledit gaz oxydant étant de l'air ou des fumées de combustion, ou un mélange composé d'air et de fumées de combustion.The invention also relates to a method of controlled oxidation of metal strips implemented in a controlled oxidation chamber mentioned above, by means of an oxidizing gas injected on at least one of the faces of the strip, said gas oxidant being air or combustion fumes, or a mixture of air and combustion fumes.

Avantageusement, on contrôle de manière distincte les caractéristiques du gaz oxydant et/ou la cinétique d'injection et d'aspiration du gaz oxydant dans les portions d'oxydation pour ajuster l'oxydation induite sur la bande sur la largeur et la longueur de la chambre d'oxydation.Advantageously, the characteristics of the oxidizing gas and / or the kinetics of injection and suction of the oxidizing gas in the oxidation portions are advantageously controlled to adjust the oxidation induced on the strip over the width and the length of the oxidation chamber.

De manière plus avantageuse, on contrôle les dimensions d'une portion d'oxydation par le choix des orifices de soufflage et des orifices d'aspiration en services dans ladite portion. A cet effet plusieurs séries d'orifices de soufflage et plusieurs séries d'orifices d'aspiration sont prévues. On effectue alors un choix parmi ces séries d'orifices en fonction de la distance souhaitée entre la zone de soufflage et la zone d'aspiration, c'est-à-dire en fonction de l'oxydation souhaitée.More advantageously, the dimensions of an oxidation portion are controlled by the choice of the blowing orifices and the suction orifices in use in said portion. For this purpose several series of blowholes and several series of suction ports are provided. We then perform a choice among these series of orifices depending on the desired distance between the blowing zone and the suction zone, that is to say according to the desired oxidation.

Le temps de séjour du gaz oxydant dans la chambre d'oxydation contrôlée peut être ajusté par la portion selon la longueur de ladite portion dans la direction de défilement de la bande.The residence time of the oxidizing gas in the controlled oxidation chamber may be adjusted by the portion along the length of said portion in the running direction of the strip.

Dans ce qui suit, l'invention est expliquée de manière détaillée sur la base d'exemples de réalisation faisant référence aux figures 1 à 7 des dessins.

  • Figure 1 est une représentation schématique partielle d'une chambre d'oxydation selon un exemple de réalisation de l'invention, telle que vue par une face de la bande, comprenant des orifices de soufflage et d'aspiration de section circulaire, réparties sur une zone de soufflage et une zone d'aspiration,
  • Figure 2 est une représentation schématique partielle d'une chambre d'oxydation selon un exemple de réalisation de l'invention similaire à celui de la figure 1, telle que vue par une face de la bande, les orifices de soufflage et d'aspiration étant de section rectangulaire,
  • Figure 3 est une représentation schématique partielle d'une chambre d'oxydation selon un exemple de réalisation de l'invention similaire à celui de la figure 2, telle que vue par une face de la bande, la paroi de la chambre d'oxydation comprenant quatre séries d'orifices au lieu de deux,
  • Figure 4 est une représentation schématique partielle d'une chambre d'oxydation selon un exemple de réalisation de l'invention similaire à celui de la figure 3, telle que vue par une face de la bande, la paroi de la chambre d'oxydation comprenant également des orifices d'aspiration placés transversalement,
  • Figure 5 est une représentation schématique partielle d'une chambre d'oxydation en coupe transversale selon un exemple de réalisation de l'invention dans lequel les orifices de soufflage ne dépassent pas des parois internes de la chambre,
  • Figure 6 est une représentation schématique partielle d'une chambre d'oxydation en coupe transversale selon un exemple de réalisation de l'invention dans lequel les orifices de soufflage dépassent des parois internes de la chambre, et
  • Figure 7 est une représentation schématique partielle d'une ligne continue comprenant une chambre d'oxydation selon un exemple de réalisation de l'invention.
In the following, the invention is explained in detail on the basis of exemplary embodiments referring to Figures 1 to 7 drawings.
  • Figure 1 is a partial schematic representation of an oxidation chamber according to an exemplary embodiment of the invention, as seen from one side of the strip, comprising circular section blow and suction ports, distributed over a zone of blowing and a suction zone,
  • Figure 2 is a partial schematic representation of an oxidation chamber according to an exemplary embodiment of the invention similar to that of the figure 1 , as seen from one side of the strip, the blow and suction ports being of rectangular section,
  • Figure 3 is a partial schematic representation of an oxidation chamber according to an exemplary embodiment of the invention similar to that of the figure 2 , as seen from one side of the strip, the wall of the oxidation chamber comprising four series of orifices instead of two,
  • Figure 4 is a partial schematic representation of an oxidation chamber according to an exemplary embodiment of the invention similar to that of the figure 3 , as seen from one side of the strip, the wall of the oxidation chamber also comprising transverse suction ports,
  • Figure 5 is a partial schematic representation of an oxidation chamber in cross-section according to an exemplary embodiment of the invention in which the blowing holes do not project beyond the internal walls of the chamber,
  • Figure 6 is a partial schematic representation of an oxidation chamber in cross-section according to an exemplary embodiment of the invention in which the blowing orifices protrude from the internal walls of the chamber, and
  • Figure 7 is a partial schematic representation of a continuous line comprising an oxidation chamber according to an exemplary embodiment of the invention.

Dans toute la description qui suit de différents modes de réalisation de l'invention, les termes relatifs tels que « avant », « arrière », « amont » et « aval » sont à interpréter au vu du sens de défilement de la bande de même que les termes tels que « au-dessus », « au-dessous » sont à interpréter au vu de la position des différents éléments sur les figures.Throughout the following description of various embodiments of the invention, the relative terms such as "before", "backward", "upstream" and "downstream" are to be interpreted in view of the direction of travel of the strip of the same that terms such as "above", "below" are to be interpreted in view of the position of the various elements in the figures.

Les figures 1 à 4 présentent en vues schématiques des exemples d'architecture de chambres d'oxydation selon l'invention dans lesquelles la bande circule selon la direction indiquée par la flèche 16, dans une zone de four oxydant ou non-oxydant. Ces figures représentent schématiquement en vue de face un exemple d'une paroi 2 d'une chambre 1 d'oxydation contrôlée selon l'invention, telle que vue par une face de la bande. Les parois de la chambre d'oxydation sont ici constituées de modules élémentaires 3 juxtaposés de forme rectangulaire. Il peut par exemple s'agir de brique en matériau réfractaire. Cependant, cet exemple de réalisation n'est qu'illustratif, d'autres modes de réalisation pouvant être utilisés. Par exemple, les parois de la chambre d'oxydation peuvent être en un seul module. Elles peuvent être garnies de fibre réfractaire, et éventuellement recouvertes d'une tôle en inox.The Figures 1 to 4 show in schematic views examples of architecture of oxidation chambers according to the invention in which the band flows in the direction indicated by the arrow 16, in a zone of oxidizing or non-oxidizing furnace. These figures show schematically in front view an example of a wall 2 of a controlled oxidation chamber 1 according to the invention, as seen by one side of the strip. The walls of the oxidation chamber here consist of elementary modules 3 juxtaposed of rectangular shape. It may for example be brick refractory material. However, this exemplary embodiment is only illustrative, other embodiments may be used. For example, the walls of the oxidation chamber may be in one module. They can be lined with refractory fiber, and possibly covered with a stainless steel sheet.

Comme on peut le voir sur ces figures, certains modules élémentaires 3 comprennent des orifices 4, 5 circulaires ou rectangulaires par lesquels est réalisée l'injection du gaz sur la bande ou son évacuation de la chambre d'oxydation. Le nombre d'orifices d'injection 4 par module élémentaire et la section unitaire de ces orifices sont choisis de sorte de couvrir toute la largeur de bande avec des jets de gaz unitaires dont la forme et la cinématique permettent de couvrir une surface unitaire de bande avec une vitesse adaptée pour assurer l'oxydation de la bande.As can be seen in these figures, certain elementary modules 3 comprise circular or rectangular orifices 4, 5 through which the gas is injected onto the strip or discharged from the oxidation chamber. The number of injection orifices 4 per elementary module and the unit section of these orifices are chosen so as to cover the entire bandwidth with unit gas jets whose shape and kinematics allow to cover a unitary band surface with a speed adapted to ensure the oxidation of the band.

Dans ces exemples, des orifices d'aspiration 5 sont placés au-dessus d'orifices de soufflage 4 mais cet exemple n'est pas restrictif, les orifices d'aspiration pouvant être placés en dessous des orifices d'injection. Dans ces exemples, si la bande circule comme représenté de bas en haut, l'écoulement du gaz injecté se fait donc dans le sens d'écoulement de la bande. Si la bande circule de haut en bas, l'écoulement du gaz injecté se fait donc dans le sens inverse de l'écoulement de la bande. Concernant l'utilisation de ces références à des positions hautes et basses, nous avons considéré que ces figures illustrent une chambre verticale. Evidemment, il pourrait également s'agir d'une chambre horizontale, avec un défilement horizontal de la bande, ou une chambre inclinée, pour laquelle la position des orifices serait alors définie plus généralement selon le sens de défilement de la bande.In these examples, suction orifices 5 are placed above blowing orifices 4, but this example is not restrictive, the suction orifices being able to be placed below the injection orifices. In these examples, if the band flows as shown from bottom to top, the flow of the injected gas is therefore in the direction of flow of the strip. If the band flows from top to bottom, the flow of the injected gas is therefore in the opposite direction of the flow of the band. Regarding the use of these references at high and low positions, we have considered that these figures illustrate a vertical chamber. Obviously, it could also be a horizontal chamber, with a horizontal scroll of the strip, or an inclined chamber, for which the position of the orifices would then be defined more generally in the direction of travel of the strip.

En figure 1, nous pouvons voir représenté un exemple de réalisation dans lequel les orifices de soufflage 4 sont situés sur deux rangées successives de modules unitaires 3. Les orifices de soufflage sont ainsi alignés sur deux lignes 6, 7 parallèles à la largeur de bande. Dans cet exemple, nous avons trois orifices par module unitaire. La position des orifices est décalée sur la seconde rangée 7 par rapport à la première rangée 6, de sorte d'obtenir un recouvrement plus important de la surface de la bande sur sa largeur. Les orifices d'aspiration 5 ont une distribution similaire et sont répartis sur deux rangées 8 et 9. La distribution des orifices d'aspiration 5 est symétrique à celle des orifices de soufflage 4 selon un axe de symétrie transversal passant à mi-distance entre les orifices de soufflage 4 et d'aspiration 5. La distance entre la zone de soufflage et la zone d'aspiration, dans le sens de défilement de la bande, est fonction de la vitesse maximale de défilement de la bande et de la cinématique du gaz oxydant soufflé sur la bande. Elle correspond ici à trois rangées de modules unitaires.In figure 1 , we can see an exemplary embodiment in which the blowing holes 4 are located in two successive rows of unit modules 3. The blowing ports are thus aligned on two lines 6, 7 parallel to the bandwidth. In this example, we have three ports per unit module. The position of the orifices is shifted to the second row 7 relative to the first row 6, so as to obtain a greater overlap of the surface of the strip over its width. The suction orifices 5 have a similar distribution and are distributed in two rows 8 and 9. The distribution of the suction orifices 5 is symmetrical to that of the blowing orifices 4 along an axis of transverse symmetry passing halfway between the The distance between the blowing zone and the suction zone, in the running direction of the strip, is a function of the maximum speed of movement of the strip and the kinematics of the gas. oxidant blown on the tape. It corresponds here to three rows of unitary modules.

Le nombre d'orifices de soufflage 4 et d'orifices d'aspiration 5 en opération et leur localisation sont ajustés selon les endroits sur la surface de la bande où il est nécessaire de réaliser une oxydation supplémentaire de la bande. Les orifices d'aspiration 5 en opération se situent naturellement dans l'alignement des orifices de soufflage 4, dans le sens de défilement de la bande.The number of blow holes 4 and suction ports 5 in operation and their location are adjusted according to the locations on the surface of the strip where it is necessary to perform additional oxidation of the strip. The suction ports 5 in operation are naturally in alignment with the blowing holes 4, in the running direction of the strip.

Le débit de gaz oxydant peut être ajusté par ligne 6, 7 d'orifices de soufflage, par ensemble d'orifices de soufflage, ou unitairement par orifice de soufflage 4, de sorte d'ajuster pour chaque orifice 4 ou ensemble d'orifices la cinématique des jets de gaz oxydant et leur effet sur la bande.The oxidizing gas flow rate can be adjusted by line 6, 7 of blowing ports, by set of blow holes, or individually by blowing orifice 4, so as to adjust for each orifice 4 or set of orifices kinematic jets of oxidizing gas and their effect on the band.

De plus, lorsque le gaz oxydant est un mélange d'air et de fumées, il est également possible de faire varier la concentration en oxygène du gaz oxydant par orifice de soufflage, ou par ensemble d'orifices de soufflage, en ajustant les proportions d'air et de fumées, de sorte d'ajuster le pouvoir oxydant des jets de gaz.In addition, when the oxidizing gas is a mixture of air and smoke, it is also possible to vary the oxygen concentration of the oxidizing gas by blowing orifice, or by set of blowing ports, by adjusting the proportions of air and smoke, so adjust the oxidizing power of the gas jets.

Nous voyons que plusieurs moyens peuvent être utilisés indépendamment ou en combinaison pour ajuster très finement l'oxydation de la bande en chaque point de celle-ci.We see that several means can be used independently or in combination to very finely adjust the oxidation of the band at each point thereof.

En figure 2, nous pouvons voir représenté en vue schématique un exemple de réalisation similaire à celui représenté en Fig. 1 mais avec des orifices de soufflage et d'aspiration de section rectangulaire. Une portion unitaire 17 délimitée par un orifice de soufflage et un orifice d'aspiration est représentée sur cette figure.In figure 2 , we can see represented diagrammatically an example of realization similar to that represented in Fig. 1 but with openings of blow and suction of rectangular section. A unit portion 17 defined by a blowing orifice and a suction orifice is shown in this figure.

La figure 3 représente schématiquement à titre d'exemple l'architecture d'une chambre d'oxydation selon l'invention ayant 8 lignes 6 à 13 d'orifices par face de bande. Cette chambre d'oxydation plus longue que celles des figures 1 et 2 est notamment adaptée pour des vitesses importantes de défilement de la bande. Par ailleurs, pour une même vitesse de défilement de la bande que celle des chambres représentées en figures 1 et 2, la longueur plus importante de la chambre d'oxydation permet de réaliser l'oxydation avec une cinématique plus lente qui peut être avantageuse pour certaines nuances d'acier.The figure 3 schematically represents by way of example the architecture of an oxidation chamber according to the invention having 8 lines 6 to 13 orifices per strip face. This oxidation chamber is longer than those of Figures 1 and 2 is particularly suitable for high speeds of tape travel. Moreover, for the same speed of travel of the strip as that of the chambers represented in Figures 1 and 2 the longer length of the oxidation chamber makes it possible to perform the oxidation with a slower kinematics which may be advantageous for certain steel grades.

Par exemple, cette chambre peut ainsi disposer de deux zones d'oxydation successives par soufflage/aspiration, les lignes d'orifices 6, 7, 10 et 11 assurant le soufflage et les lignes 8, 9, 12 et 13 l'aspiration. Il est par exemple possible de dédier chacune à un gaz de nature différente, ou de souffler un même gaz avec deux cinématiques d'injection différentes.For example, this chamber can thus have two successive oxidation zones by blow / suction, the lines of orifices 6, 7, 10 and 11 ensuring the blowing and the lines 8, 9, 12 and 13 the suction. It is for example possible to dedicate each to a gas of different nature, or to blow the same gas with two different injection kinematics.

Cette chambre peut également être exploitée en utilisant uniquement les lignes d'orifices 6 et 7 pour le soufflage du gaz oxydant et les lignes 8 à 13 en aspiration. Selon la longueur d'échange souhaitée entre le gaz oxydant et la bande, les orifices d'aspiration utilisés seront soit ceux des lignes 8 et 9, soit ceux des lignes 10 et 11 ou soit ceux des lignes 12 et 13, les lignes 8 et 9 conduisant à la longueur d'échange la plus courte et les lignes 12 et 13 à la longueur d'échange la plus longue.This chamber can also be operated using only the lines of orifices 6 and 7 for blowing the oxidizing gas and lines 8 to 13 in suction. Depending on the desired exchange length between the oxidizing gas and the strip, the suction ports used will be those of the lines 8 and 9, or those of the lines 10 and 11 or those of the lines 12 and 13, the lines 8 and 9 leading to the shortest exchange length and lines 12 and 13 to the longest exchange length.

La figure 4 représente schématiquement à titre d'exemple l'architecture d'une chambre d'oxydation selon l'invention dans le même principe que celle de la figure 3 mais présentant avantageusement des aspirations transversales 14 disposées successivement selon la largeur du four. La présence de ces aspirations transversales 14 permet de délimiter précisément sur la largeur de bande, et sur la longueur de la chambre d'oxydation, des zones dans lesquelles l'oxydation peut être contrôlée de manière séparée.The figure 4 schematically represents by way of example the architecture of an oxidation chamber according to the invention in the same principle as that of the figure 3 but advantageously having transverse aspirations 14 arranged successively according to the width of the oven. The presence of these transverse aspirations 14 makes it possible to delimit precisely on the bandwidth, and the length of the oxidation chamber, zones in which the oxidation can be controlled separately.

Le dispositif selon l'invention peut ainsi être composé d'un système de soufflage longitudinal en plusieurs parties contrôlées indépendamment et d'un système d'aspiration disposé en alternance au soufflage et disposé à une distance avantageuse permettant le contrôle de la valeur d'oxyde souhaité sur la bande. Les parties aspiration et soufflage de la zone considérée sont commandées simultanément ce qui permet au débit d'air injecté de s'évacuer après un temps de séjour équivalent à la distance définie et de ne pas se diffuser latéralement vers d'autres zones de la bande, et donc provoquer d'oxydation non désirée sur d'autres zones de la bandeThe device according to the invention can thus be composed of a longitudinal blowing system in several independently controlled parts and of a suction system alternately disposed at blowing and disposed at an advantageous distance allowing the control of the oxide value. desired on the tape. The suction and blowing parts of the zone in question are controlled simultaneously, which allows the flow of injected air to escape after a residence time equivalent to the defined distance and not to diffuse laterally to other zones of the strip. , and thus cause unwanted oxidation on other areas of the band

La figure 5 représente schématiquement une vue en coupe d'une chambre d'oxydation 1 au niveau d'orifices de soufflage 4, selon un exemple de réalisation de l'invention. Dans cet exemple, les orifices de soufflage ne dépassent pas des modules unitaires 3 en direction de la bande 15.The figure 5 schematically represents a sectional view of an oxidation chamber 1 at the level of blowing orifices 4, according to an exemplary embodiment of the invention. In this example, the blowing holes do not exceed unit modules 3 in the direction of the strip 15.

La figure 6 représente schématiquement une vue en coupe d'une chambre d'oxydation 1 au niveau d'orifices de soufflage 4, selon un autre exemple de réalisation de l'invention dans lequel les orifices de soufflage dépassent des modules unitaires 3 en direction de la bande 15.The figure 6 schematically represents a sectional view of an oxidation chamber 1 at the level of blowing orifices 4, according to another embodiment of the invention in which the blowing orifices protrude from the unitary modules 3 in the direction of the strip 15 .

Dans les 2 exemples de réalisation des figures 5 et 6, les orifices d'aspiration ne sont pas représentés. Ils peuvent ne pas dépasser des modules unitaires 3 en direction de la bande 15 ou dépasser desdits modules. Sur une chambre d'oxydation selon l'invention, les orifices de soufflage et d'aspiration peuvent ne pas dépasser des modules unitaires 3 en direction de la bande 15, les orifices de soufflage peuvent ne pas dépasser alors que les orifices d'aspiration dépassent, et les orifices de soufflage peuvent dépasser alors que les orifices d'aspiration ne dépassent pas.In the two exemplary embodiments of Figures 5 and 6 the suction ports are not shown. They may not exceed unit modules 3 in the direction of the band 15 or exceed said modules. On an oxidation chamber according to the invention, the blowing and suction orifices may not exceed unitary modules 3 in the direction of the strip 15, the blowing orifices may not exceed while the suction orifices exceed , and the blowing holes may protrude while the suction ports do not protrude.

La distance entre la bande et l'extrémité des orifices de soufflage et d'aspiration est notamment lié au débit et à la cinématique des jets de gaz oxydant.The distance between the strip and the end of the blowing and suction ports is particularly related to the flow rate and kinematics of the oxidizing gas jets.

L'inventeur précise que le débit minimum d'injection d'air dans la zone d'oxydation étant très faible (par exemple 10 Nm3/h d'air pour un écoulement du gaz oxydant sur une longueur d'un mètre, mesurée entre soufflage et aspiration et/ou longueur, dans le sens longitudinal de défilement de la bande, correspondant à la portion d'oxydation souhaitée, ladite longueur donnant une épaisseur d'oxyde de 70 nm sur une bande de 1500 mm de large défilant à 100m/mn à une température de 650°C), le contrôle de l'oxydation peut se faire avantageusement par l'ouverture / fermeture d'une ou plusieurs zones d'oxydation (soufflage / aspiration) et ainsi d'en faire varier le débit global pour varier le temps de séjour sous gaz oxydant de la bande et donc faire varier l'épaisseur d'oxyde. Dans le cas où une partie seulement des zones est utilisée en oxydation, et afin de ne pas diffuser le gaz oxydant dans d'autres zones, celui-ci peut être remplacé par un débit azote faisant écran avec la zone d'oxydation utilisée.The inventor states that the minimum air injection flow rate in the oxidation zone is very low (for example 10 Nm 3 / h of air for a flow of the oxidizing gas over a length of one meter, measured between blowing and suction and / or length, in the longitudinal direction of travel of the strip, corresponding to the desired oxidation portion, said length giving an oxide thickness of 70 nm on a strip of 1500 mm wide scrolling at 100m / min at a temperature of 650 ° C.), the control of the oxidation can be advantageously done by the opening / closing of one or more oxidation zones (blowing / suction) and thus of varying the overall flow rate for vary the residence time under oxidizing gas of the strip and thus vary the oxide thickness. In the case where only part of the zones is used in oxidation, and in order not to diffuse the oxidizing gas in other zones, it can be replaced by a nitrogen flow screen with the oxidation zone used.

Cette opération peut être réalisée sur toute la largeur de la bande ou bien sur une partie seulement, donnant ainsi une grande souplesse dans la gestion de l'atmosphère en contact avec la bande tout en conservant au minimum les vitesses critiques d'injection sur la bande dans la zone d'oxydation souhaitée et en isolant les autres zones par injection d'un gaz neutre comme l'azote par exemple. Ce mode de fonctionnement permet de s'affranchir de la vitesse de défilement de la bande dans le contrôle de l'épaisseur d'oxyde.This operation can be performed over the entire width of the strip or only a part, thus giving great flexibility in the management of the atmosphere in contact with the strip while keeping at least the critical injection speeds on the strip in the desired oxidation zone and isolating the other zones by injection of a neutral gas such as nitrogen for example . This operating mode makes it possible to dispense with the speed of travel of the strip in the control of the oxide thickness.

Selon un exemple avantageux d'implantation, le dispositif selon l'invention est placé en aval d'une section d'oxydation sans contrôle précis de l'oxydation sur la largeur de bande. Celle-ci permet, par exemple, de réaliser rapidement, c'est-à-dire sur une longueur de four limitée, l'essentiel de la couche d'oxydes visée. Le dispositif selon l'invention permet alors de réaliser localement un complément d'oxydation, par exemple pour obtenir une épaisseur d'oxydes homogène sur la largeur de bande ou pour renforcer celle-ci localement.According to an advantageous example of implantation, the device according to the invention is placed downstream of an oxidation section without precise control of the oxidation over the bandwidth. This allows, for example, to achieve quickly, that is to say, over a limited furnace length, most of the oxide layer referred to. The device according to the invention then makes it possible locally to carry out additional oxidation, for example to obtain a homogeneous oxide thickness over the bandwidth or to reinforce it locally.

La section d'oxydation sans contrôle précis de l'oxydation sur la largeur de bande peut également permettre de réaliser une couche dont les oxydes auront une morphologie ou une composition donnée, différente de la couche superficielle qui sera réalisée ensuite par le dispositif selon l'invention.The oxidation section without precise control of the oxidation over the bandwidth may also make it possible to produce a layer whose oxides will have a given morphology or composition, different from the surface layer which will then be produced by the device according to the invention. invention.

Description détaillée d'un exemple de réalisation de l'inventionDetailed description of an exemplary embodiment of the invention

Selon un exemple de réalisation de l'invention, représenté en Figure 7, la section 100 d'oxydation sans contrôle précis de l'oxydation sur la largeur de bande est une portion d'un four 110 de préchauffage de la bande par flamme directe. Depuis l'entrée de la bande, ce four comprend une zone 120 de préchauffage de la bande par épuisement des fumées suivi d'une zone 130 de chauffage équipée de brûleurs à flamme directe. Dans cet exemple de réalisation, dans le sens de défilement de la bande, les 15 premières paires de brûleurs (sur 13 m de longueur de four) fonctionnent en défaut d'air de sorte d'éviter d'oxyder la bande. Les 3 dernières paires de brûleurs (sur 4.2 m de longueur de four) délimitent la section 100 dans laquelle les brûleurs fonctionnent avec un fort excès d'air pour obtenir une importante oxydation de la bande. Le dispositif 1 selon l'invention placé en aval de cette zone oxydante permet ensuite d'ajuster finement l'oxydation sur la largeur de bande.According to an exemplary embodiment of the invention, represented in Figure 7 , the oxidation section 100 without precise control of the oxidation on the bandwidth is a portion of a preheating furnace 110 of the direct flame band. From the entrance of the strip, this oven comprises a zone 120 for preheating the strip by exhausting the flue gas followed by a heating zone 130 equipped with direct flame burners. In this embodiment, in the running direction of the strip, the first 15 pairs of burners (over 13 m of oven length) operate in air defect so as to avoid oxidation of the band. The last 3 pairs of burners (over 4.2 m of oven length) delimit the section 100 in which the burners operate with a large excess of air to obtain a significant oxidation of the band. The device 1 according to the invention placed downstream of this oxidizing zone then makes it possible to finely adjust the oxidation on the bandwidth.

La bande de largeur 1500 mm circule à une vitesse nominale de 100 m/min. La chambre 1 à une longueur de 475 mm dans le sens de défilement de la bande. La zone de soufflage comporte 55 orifices disposés sur deux lignes transversales distantes de 80 mm. La zone d'aspiration comporte 55 orifices disposés sur deux lignes transversales distantes de 80 mm. La distance entre les lignes de soufflage et d'aspiration les plus proches est de 315 mm. Les orifices de soufflage sont disposés à 100 mm de la bande tous les 58 mm selon la largeur de bande. Leur diamètre d'injection est de 25 mm. Les orifices d'aspiration sont disposés à 100 mm de la bande tous les 58 mm selon la largeur de bande. Leur diamètre d'aspiration est de 25 mm.The width of 1500 mm band is running at a nominal speed of 100 m / min. The chamber 1 has a length of 475 mm in the direction of travel of the strip. The blowing zone has 55 orifices arranged on two transverse lines 80 mm apart. The suction zone has 55 orifices arranged on two transverse lines 80 mm apart. The distance between the nearest blow and suction lines is 315 mm. The blow holes are located 100 mm from the strip every 58 mm depending on the bandwidth. Their injection diameter is 25 mm. The suction ports are located 100 mm from the belt every 58 mm depending on the bandwidth. Their suction diameter is 25 mm.

Le gaz oxydant est de l'air. Il est injecté sur la bande à une vitesse nominale de 3 m/s. La vitesse d'injection est modulée par injecteur, ou ensemble d'injecteur, entre 0 et 5 m/s selon l'importance de l'oxydation recherchée sur la surface de la bande concernée. La bande est à 650°C lors de son entrée dans la chambre d'oxydation. Le gaz oxydant est injecté à une température de 650°C.The oxidizing gas is air. It is injected on the belt at a nominal speed of 3 m / s. The injection speed is modulated by injector, or injector assembly, between 0 and 5 m / s depending on the amount of oxidation sought on the surface of the band concerned. The band is at 650 ° C when it enters the oxidation chamber. The oxidizing gas is injected at a temperature of 650 ° C.

Claims (10)

  1. Chamber (1) for the controlled oxidation of metal strips in an annealing furnace of a continuous production line for hot-coated strips, for example by galvanizing, the oxidation chamber for the oxidation of the metal strips by means of an oxidizing gas injected on at least one of the sides of a strip (15), characterized in that the oxidation chamber comprises oxidizing portions (17) extending over its width and/or length, each portion comprising at least one blowing port (4) and at least one suction port (5) between which an oxidizing gas circulates; each portion can be controlled separately to adjust the oxidation induced on the strip over the width and length of the oxidation chamber.
  2. Controlled oxidation chamber (1) according to Claim 1, characterized in that the oxidizing gas is injected onto the strip (15) in a direction substantially perpendicular to the strip by means of blowing ports (4) and in that then the oxidizing gas circulates in the chamber (1) to suction ports (5) in a direction substantially parallel to the moving direction of the strip.
  3. Controlled oxidation chamber (1) according to Claim 1, characterized in that it is placed downstream, in the moving direction of the strip (15), a section (100) in which the strip undergoes a first oxidation.
  4. Controlled oxidation chamber (1) according to any one of the preceding claims, characterized in that the oxidizing gas used is air.
  5. Controlled oxidation chamber (1)according to any one of the preceding claims, characterized in that the oxidizing gas used is a mixture of air and flue gas.
  6. Controlled oxidation chamber (1) according to any one of the preceding claims, characterized in that it comprises at least one oxidation sensor situated upstream and/or downstream of the oxidation portion (17), information from the oxidation sensor being integrated into the calculation of the oxidizing gas flow leaving the blowing port (4) of the oxidation portion (17).
  7. Process of controlled oxidation of metal strips implemented in a controlled oxidation chamber (1) according to the preceding claims, by means of an oxidizing gas injected on at least one of the sides of the strip (15), characterized in that the said oxidizing gas is air or combustion flue gas, or a mixture of air and combustion flue gas.
  8. Oxidation process according to claim 7 characterized in that the characteristics of the oxidizing gas and/or the kinetics of injection and suction of the oxidizing gas in the portions (17) are controlled separately to adjust the oxidation on the strip over the width and length of the oxidation chamber.
  9. Oxidation process according to Claim 7 or 8, characterized in that the dimensions of a portion (17) are controlled by the choice of the blowing ports (4) and the suction ports (5) operating in said portion.
  10. Oxidation process according to Claim 9, characterized by the fact that the residence time of the oxidizing gas in the controlled oxidation chamber (1) is adjusted by portion (17) according to the length of said portion (17) in the moving direction of the strip.
EP16822660.3A 2015-12-30 2016-12-19 Device and method for carrying out controlled oxidation of metal strips in a continuous furnace Active EP3397786B1 (en)

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PCT/EP2016/081730 WO2017114682A1 (en) 2015-12-30 2016-12-19 Device and method for carrying out controlled oxidation of metal strips in a continuous furnace

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TW420718B (en) * 1995-12-26 2001-02-01 Nippon Steel Corp Primary cooling method in continuously annealing steel strip
US6241515B1 (en) * 2000-05-30 2001-06-05 Tat Technologies, Inc Device and method for treating combustibles obtained from a thermal processing apparatus and apparatus employed thereby
JP4168667B2 (en) * 2002-05-30 2008-10-22 Ｊｆｅスチール株式会社 In-line annealing furnace for continuous hot dip galvanizing
FR2852330B1 (en) * 2003-03-12 2007-05-11 Stein Heurtey METHOD OF CONTROLLED OXIDATION OF STRIPS BEFORE CONTINUOUS GALVANIZATION AND LINE OF GALVANIZATION
FR2920439B1 (en) * 2007-09-03 2009-11-13 Siemens Vai Metals Tech Sas METHOD AND DEVICE FOR THE CONTROLLED OXIDATION / REDUCTION OF THE SURFACE OF A CONTINUOUSLY STRAY STEEL BAND IN A RADIANT TUBE OVEN FOR ITS GALVANIZATION
ES2359594T3 (en) * 2008-03-14 2011-05-25 Arcelormittal France GAS BLOWING PROCEDURE AND DEVICE ON A CIRCULATING BAND.
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FR3046423B1 (en) 2018-04-13
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US11131004B2 (en) 2021-09-28
FR3046423A1 (en) 2017-07-07
WO2017114682A1 (en) 2017-07-06
ES2770080T3 (en) 2020-06-30

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