WO2015097379A1 - Alloy with stable microstructure for reforming tubes - Google Patents

Alloy with stable microstructure for reforming tubes Download PDF

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WO2015097379A1
WO2015097379A1 PCT/FR2014/053450 FR2014053450W WO2015097379A1 WO 2015097379 A1 WO2015097379 A1 WO 2015097379A1 FR 2014053450 W FR2014053450 W FR 2014053450W WO 2015097379 A1 WO2015097379 A1 WO 2015097379A1
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weight
nitrogen
alloy
nitrides
gas stream
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PCT/FR2014/053450
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French (fr)
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Pascal Del-Gallo
Jader Furtado
Daniel Gary
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L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
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Publication of WO2015097379A1 publication Critical patent/WO2015097379A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
    • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
    • C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
    • C01B3/384—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts the catalyst being continuously externally heated
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
    • C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
    • C22C19/056—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 10% but less than 20%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C22C19/058—Alloys based on nickel or cobalt based on nickel with chromium without Mo and W
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium

Definitions

  • the present invention relates to alloys of iron, nickel and chromium having a stable microstructure, particularly under elevated temperature conditions (900-1050 ° C) and / or high pressure (10-10 ° C). -40 bars) and a process for manufacturing reforming tubes comprising such an alloy.
  • Alloys of this type can be used for the manufacture of reforming tubes for the production of syngas (a mixture of H2 and CO), but also for the manufacture of furnaces.
  • the re-forming tubes are filled with nickel catalyst supported on alumina.
  • the decomposition reaction of methane is endothermic and needs an external heat source, which is usually installed inside a combustion chamber equipped with burners.
  • These operating conditions impose two main requirements on the reforming tubes, namely the tubes must be resistant to oxidation at high temperature and most important to creep deformation.
  • the installations use standard tubes where the microstructure is not controlled or stabilized despite the severe conditions of temperature and pressure.
  • the alloy can age rapidly which will lead to premature failure and thus a loss of synthesis gas production often associated with fines paid by the customer for the uninterrupted supply of hydrogen and carbon monoxide.
  • alloys of reforming tubes have limited creep resistance if exposed to temperatures above 900 ° C.
  • a solution of the present invention is an alloy of iron, nickel and chromium for a reforming tube comprising from 20 to 35% by weight of Cr, from 20 to 45% by weight of Ni, and from 0.2 to
  • nitrogen between 0 and 0.5%, preferably between 0.10 and 0.30% and more preferably between 0.1 and 0.2%.
  • the alloy according to the invention having nitrogen as an element will have a temperature resistance greater than 450 ° C, preferably greater than 900 ° C, more preferably 950 ° C.
  • Nitrogen as an interstitial atom has some characteristics common to other interstitial atoms, such as carbon. However, an alloy with nitrogen has several advantages over an alloy with carbon:
  • Nitrogen is a solid hardener-solution more effective than carbon and also improves the size of eutectic cells during the solidification of the alloy;
  • Nitrogen is a strong austenite stabilizer thus reducing the amount of nickel required for the stabilization of the alloy
  • nitrogen has a greater solubility than carbon, which decreases the precipitation tendency at a given level of resistance
  • the solubility of nitrogen in Fe alloys and more particularly in Fe-Cr-Ni is dependent on temperature, pressure and chemical composition. At 1600 ° C and pressure In the atmosphere, the solubility of nitrogen in liquid iron is 0.045%, and at low pressures it follows Sievert's law, being proportional to the square root of nitrogen. However, for high concentrations of Cr in Fe-Cr alloys there is an increase in the solubility of nitrogen with increasing Cr concentration.
  • the present invention also relates to a process for manufacturing a reformer tube, dedicated to the production of hydrogen-rich synthesis gas and CO (carbon monoxide), comprising an alloy according to the invention, characterized in that before injecting the boiling alloy, an oxygen-free gas stream comprising nitrogen, preferably at least 95% by weight of nitrogen, more preferably at least 99% by weight of nitrogen, is injected; or only nitrogen.
  • an oxygen-free gas stream comprising nitrogen, preferably at least 95% by weight of nitrogen, more preferably at least 99% by weight of nitrogen, is injected; or only nitrogen.
  • the method according to the invention has one or more of the following characteristics:
  • the injection conditions of the gas stream are chosen so as to have a precipitation of carbides, nitrides and / or carbo-nitrides in the range of 10 to 500 nanometers, preferably in the range of 20 to 150 nanometers.
  • the gaseous flow is injected under a controlled flow rate capable of overcoming the hydrostatic height of the bath.
  • the gaseous flow is injected by means of a ceramic lance with a porous ceramic plug, placed in the center of the refining pot; or a porous ceramic plug and placed in the bottom of the refining pot or on the side walls of the refining pot; or a combination of these means.
  • nitrogen is transferred to the melt through the following mechanisms:
  • the diatomic molecule of nitrogen (N2) is dissociated in atomic (N) via a reaction at the gas-melt interface, or
  • nitride metals or nitride compounds directly into liquid slag or metal.
  • the state of the art indicates that nitrogen can to be provided by the addition of nitrogen-rich precursors, such as Si 3 Ni 4 (25 to 30% by weight of N), CrN (4-10% by weight of N) and FeCrN (8-10% by weight of N). ).
  • the object of the present invention is to apply nitrogen to have a desired precipitation of nitrides and carbo-nitrides in the microstructure of the reforming tubes, which are stable at high temperatures, i.e. greater than 900 ° C.
  • the amount of nitrogen to be injected into the molten alloy is a function of the chemical composition of the initial alloy specified for the forming tube. Nitrogen maintained in excess in the final microstructure will improve creep resistance.
  • the parameters to be controlled during the injection operation are as follows: the type of atmosphere around the molten metal in the refining chamber, the nitrogen flow rate, the temperature of the molten liquid alloy, the chemical composition and the injection time of the gas stream.
  • the control of these parameters will make it possible to homogenize the temperature and the chemical composition of the melt with an impact on the microstructure of the cast product.
  • the reforming tubes comprising an alloy according to the invention can be used for the production of synthesis gas, or for the manufacture of heat treatment furnaces.

Abstract

Alloy of iron, of nickel and of chromium for reforming tube comprising from 20 to 35% by weight of Cr, from 20 to 45% by weight of Ni, and from 0.2 to 0.6% by weight of C, additionally comprising: - from 0.5 to 2% by weight of Nb, - from 0 to 3% by weight of W, - from 0 to 2% by weight of V, - from 0 to 1% by weight of Zr, - from 0 to 2% by weight of Mo, - from 0.5 to 2.5% by weight of Si, - from 0 to 1% by weight of Ti, nitrogen between 0 and 0.5%, - the balance to 100% by weight in iron.

Description

ALLIAGE AVEC MICROSTRUCTURE STABLE POUR TUBES DE REFORMAGE La présente invention concerne des alliages de fer, de nickel et de chrome ayant une microstructure stable, en particulier dans des conditions de température élevées (900-1050°C) et/ou de pression élevées (10-40 bars) et un procédé de fabrication de tubes de reformage comprenant un tel alliage.  The present invention relates to alloys of iron, nickel and chromium having a stable microstructure, particularly under elevated temperature conditions (900-1050 ° C) and / or high pressure (10-10 ° C). -40 bars) and a process for manufacturing reforming tubes comprising such an alloy.
Les alliages de ce type peuvent être utilisés pour la fabrication des tubes de reformage pour la production de gaz de synthèse (un mélange de H2 et de CO), mais également pour la fabrication de fours. Les tubes de re formage sont remplis de catalyseur au nickel supporté sur alumine. La réaction de décomposition du méthane est endothermique et a besoin d'une source de chaleur externe, qui est généralement installée à l'intérieur d'une chambre de combustion équipée de brûleurs. Ces conditions de fonctionnement imposent deux exigences principales aux tubes de reformage, à savoir les tubes doivent être résistants à l'oxydation à haute température et le plus important à la déformation par fluage. Actuellement, les installations utilisent des tubes standards où la microstructure n'est pas contrôlée ou stabilisée malgré les conditions sévères de température et de pression.  Alloys of this type can be used for the manufacture of reforming tubes for the production of syngas (a mixture of H2 and CO), but also for the manufacture of furnaces. The re-forming tubes are filled with nickel catalyst supported on alumina. The decomposition reaction of methane is endothermic and needs an external heat source, which is usually installed inside a combustion chamber equipped with burners. These operating conditions impose two main requirements on the reforming tubes, namely the tubes must be resistant to oxidation at high temperature and most important to creep deformation. Currently, the installations use standard tubes where the microstructure is not controlled or stabilized despite the severe conditions of temperature and pressure.
Dans ces conditions sévères, l'alliage peut vieillir rapidement ce qui entraînera une rupture prématurée et donc une perte de production du gaz de synthèse associée souvent à des amendes versées par le client pour la fourniture ininterrompue d'hydrogène et de monoxyde de carbone.  Under these severe conditions, the alloy can age rapidly which will lead to premature failure and thus a loss of synthesis gas production often associated with fines paid by the customer for the uninterrupted supply of hydrogen and carbon monoxide.
Autrement dit les alliages des tubes de reformage présentent une résistance au fluage limitée s'il est exposé à des températures supérieures à 900°C.  In other words alloys of reforming tubes have limited creep resistance if exposed to temperatures above 900 ° C.
Partant de là, un problème qui se pose est de fournir un alliage présentant une meilleure microstructure permettant de mieux résister aux températures et pressions élevées. From there, a problem is to provide an alloy having a better microstructure to better withstand high temperatures and pressures.
Une solution de la présente invention est un alliage de fer, de nickel et de chrome pour tube de reformage comprenant de 20 à 35% en poids de Cr, de 20 à 45% en pois de Ni, et de 0.2 à A solution of the present invention is an alloy of iron, nickel and chromium for a reforming tube comprising from 20 to 35% by weight of Cr, from 20 to 45% by weight of Ni, and from 0.2 to
0.6%) en poids de C, comprenant: 0.6%) by weight of C, comprising:
- de 0,5 à 2% en poids de Nb, from 0.5 to 2% by weight of Nb,
- de 0 à 3%o en poids de W,  from 0 to 3% by weight of W,
- de 0 à 2%> en poids de V,  from 0 to 2% by weight of V,
- de 0 à l%o en poids de Zr,  from 0 to 1% by weight of Zr,
- de 0 à 2%> en poids de Mo,  from 0 to 2% by weight of Mo,
- de 0.5 à 2.5% en poids de Si - de 0 à 1% en poids de Ti from 0.5 to 2.5% by weight of Si from 0 to 1% by weight of Ti
- de l'azote entre 0 et 0.5%, préférentiellement entre 0,10 et 0,30% et plus préférentiellement entre 0,1 et 0,2%.  nitrogen between 0 and 0.5%, preferably between 0.10 and 0.30% and more preferably between 0.1 and 0.2%.
- le complément sur 100% en poids étant du fer.  the complement on 100% by weight being iron.
L'alliage selon l'invention présentant de l'azote comme élément présentera une résistance à la température supérieure à 450°C, de préférence supérieure à 900°C, plus préférentiellement à 950°C. The alloy according to the invention having nitrogen as an element will have a temperature resistance greater than 450 ° C, preferably greater than 900 ° C, more preferably 950 ° C.
L'azote comme atome interstitiel présente quelques caractéristiques communes à d'autres atomes interstitiels, comme le carbone. Cependant, un alliage avec de l'azote présente plusieurs avantages par rapport à un alliage avec le carbone :  Nitrogen as an interstitial atom has some characteristics common to other interstitial atoms, such as carbon. However, an alloy with nitrogen has several advantages over an alloy with carbon:
- l'azote est un durcisseur solide-solution plus efficace que le carbone et améliore également la taille des cellules eutectiques lors de la solidification de l'alliage;  Nitrogen is a solid hardener-solution more effective than carbon and also improves the size of eutectic cells during the solidification of the alloy;
- l'azote est un fort stabilisateur d'austénite réduisant ainsi la quantité de nickel requise pour la stabilisation de l'alliage ;  - Nitrogen is a strong austenite stabilizer thus reducing the amount of nickel required for the stabilization of the alloy;
- l'azote réduit la tendance à la formation de ferrite et à la déformation induite par les martensites a' (alpha prime) et ε (epsilon) ; - Nitrogen reduces the tendency to ferrite formation and deformation induced by martensites a '(alpha prime) and ε (epsilon);
- l'azote à une plus grande solubilité que le carbone, ce qui diminue la tendance à la précipitation à un niveau donné de résistance, et  nitrogen has a greater solubility than carbon, which decreases the precipitation tendency at a given level of resistance, and
- l'azote apporte une meilleure résistance à la corrosion.  - Nitrogen provides better resistance to corrosion.
Cependant, l'azote doit être plus contrôlé car il peut diminuer la ténacité à basse température. Cependant, ce n'est pas un problème en ce qui concerne la production de gaz de synthèse. Les types d'alliage comme ceux utilisés dans les unités de reformage sont généralement du type Fe-Cr-Ni mais avec une composition et une microstructure spécifique pour satisfaire aux exigences de température, corrosion et fluage spécifiques à ce processus. Il faut comprendre que la solubilité de l'azote sera affectée par d'autres éléments chimiques utilisés dans la fabrication de l'alliage. Dans le cas du fer liquide à 1600°C, cette évaluation a été effectuée en normalisant l'effet de divers éléments chimiques à l'effet du Cr (Figure 1). Les éléments Ti, Zr, V, Nb, Cr, Mn et Mo ont une influence positive sur la solubilité de l'azote dans le fer liquide, autrement dit ils améliorent la solubilité de l'azote dans le fer. Cependant, ils ont une tendance à entraîner la formation de nitrure à l'état solide et doivent être contrôlés. Les éléments chimiques Ni, Cu, Al, Si, B et C ont une plus faible solubilité que l'azote dans le fer liquide. However, nitrogen needs to be more controlled as it can decrease the toughness at low temperatures. However, this is not a problem with respect to the production of syngas. Alloy types such as those used in reforming units are generally of the Fe-Cr-Ni type but with a specific composition and microstructure to meet the temperature, corrosion and creep requirements specific to this process. It should be understood that the solubility of nitrogen will be affected by other chemical elements used in the manufacture of the alloy. In the case of liquid iron at 1600 ° C, this evaluation was carried out by normalizing the effect of various chemical elements on the effect of Cr (Figure 1). The elements Ti, Zr, V, Nb, Cr, Mn and Mo have a positive influence on the solubility of nitrogen in liquid iron, in other words they improve the solubility of nitrogen in iron. However, they have a tendency to lead to the formation of solid state nitride and must be controlled. The chemical elements Ni, Cu, Al, Si, B and C have a lower solubility than nitrogen in liquid iron.
La solubilité de l'azote dans les alliages Fe et plus particulièrement Fe-Cr-Ni est dépendante de la température, la pression et la composition chimique. A 1600°C et à la pression atmosphérique, la solubilité de l'azote dans le fer liquide est de 0,045%, et pour des basses pressions il suit la loi de Sievert, étant proportionnelle à la racine carrée de l'azote. Toute fois pour les concentrations élevées de Cr dans les alliages Fe-Cr il y a une augmentation de la solubilité de l'azote avec l'augmentation de la concentration Cr. The solubility of nitrogen in Fe alloys and more particularly in Fe-Cr-Ni is dependent on temperature, pressure and chemical composition. At 1600 ° C and pressure In the atmosphere, the solubility of nitrogen in liquid iron is 0.045%, and at low pressures it follows Sievert's law, being proportional to the square root of nitrogen. However, for high concentrations of Cr in Fe-Cr alloys there is an increase in the solubility of nitrogen with increasing Cr concentration.
Comme le montre la Figure 2 la relation entre les concentrations d'azote dans les alliages Fe- Cr et la concentration de Cr s'écarte fortement de la loi de Sievert, mais maintient encore l'effet positif du Cr dans l'augmentation de la limite de solubilité de l'azote dans ces alliages. Le même comportement est valable pour les alliages Fe-Cr-Ni. Une conséquence de la plus forte teneur en azote dans l'alliage est la formation de nitrures. La quantité et le contrôle des nitrures et des carbo-nitrures est une caractéristique importante pour les alliages résistants à la chaleur et doit être contrôlée. As shown in Figure 2 the relationship between nitrogen concentrations in Fe-Cr alloys and Cr concentration strongly deviates from Sievert's law, but still maintains the positive effect of Cr in the increase in solubility limit of nitrogen in these alloys. The same behavior is valid for Fe-Cr-Ni alloys. A consequence of the higher nitrogen content in the alloy is the formation of nitrides. The quantity and control of nitrides and carbo-nitrides is an important feature for heat-resistant alloys and must be controlled.
La présente invention a également pour objet un procédé de fabrication d'un tube pour reformeurs, dédié à la production du gaz de synthèse riche en hydrogène et du CO (monoxyde de carbone), comprenant un alliage selon l'invention, caractérisé en ce que l'on injecte avant la coulée de l'alliage en ébullition un flux gazeux exempt d'oxygène et comprenant de l'azote, de préférence au moins 95% en poids d'azote, plus préférentiellement au moins 99% en poids d'azote ou uniquement de l'azote.  The present invention also relates to a process for manufacturing a reformer tube, dedicated to the production of hydrogen-rich synthesis gas and CO (carbon monoxide), comprising an alloy according to the invention, characterized in that before injecting the boiling alloy, an oxygen-free gas stream comprising nitrogen, preferably at least 95% by weight of nitrogen, more preferably at least 99% by weight of nitrogen, is injected; or only nitrogen.
Selon le cas, le procédé selon l'invention présente une ou plusieurs des caractéristiques ci- dessous :  Depending on the case, the method according to the invention has one or more of the following characteristics:
- que les conditions d'injection du flux gazeux sont choisies de manière à avoir une précipitation des carbures, des nitrures et/ou des carbo-nitrures dans la gamme de 10 à 500 nanomètres, de préférence dans la gamme de 20 à 150 nanomètres. that the injection conditions of the gas stream are chosen so as to have a precipitation of carbides, nitrides and / or carbo-nitrides in the range of 10 to 500 nanometers, preferably in the range of 20 to 150 nanometers.
- le flux gazeux est injecté sous débit contrôlé capable de vaincre la hauteur hydrostatique du bain.  the gaseous flow is injected under a controlled flow rate capable of overcoming the hydrostatic height of the bath.
- le flux gazeux est injecté au moyen d'une lance céramique avec un bouchon poreux en céramique, placée dans le centre du pot de raffinage ; ou d'un bouchon poreux en céramique et placé dans le fond du pot de raffinage ou sur les parois latérales du pot de raffinage ; ou d'une combinaison de ces moyens. the gaseous flow is injected by means of a ceramic lance with a porous ceramic plug, placed in the center of the refining pot; or a porous ceramic plug and placed in the bottom of the refining pot or on the side walls of the refining pot; or a combination of these means.
De manière générale, l'azote est transféré dans la masse fondue par l'intermédiaire des mécanismes suivants :  In general, nitrogen is transferred to the melt through the following mechanisms:
- la molécule diatomique de l'azote (N2) est dissociée en atomique(N) par l'intermédiaire d'une réaction à l'interface gaz-masse fondue, ou  the diatomic molecule of nitrogen (N2) is dissociated in atomic (N) via a reaction at the gas-melt interface, or
- l'introduction de métaux de nitrure ou composés de nitrure directement dans le laitier liquide ou le métal. Dans le cas des alliages résistants à la chaleur du type Fe-Cr-Ni, à forte valeur ajouté, avec une résistance mécanique accrue, utilisé comme tube de re formage, l'état de l'art nous indique que de l'azote peut être apporter par l'addition de précurseurs riches en azote, tels que Si3Ni4 (25à 30% en poids de N), CrN (4-10% en poids de N) et FeCrN( 8-10% en poids de N). the introduction of nitride metals or nitride compounds directly into liquid slag or metal. In the case of heat-resistant alloys of the Fe-Cr-Ni type, with high added value, with increased mechanical strength, used as a forming tube, the state of the art indicates that nitrogen can to be provided by the addition of nitrogen-rich precursors, such as Si 3 Ni 4 (25 to 30% by weight of N), CrN (4-10% by weight of N) and FeCrN (8-10% by weight of N). ).
Toutefois, dans le cas de types d'alliages pour la production de tubes de reformage, les procédés mentionnés ci-dessus sont rarement utilisés à ce propos. Néanmoins, le but de la présente invention est d'appliquer de l'azote pour avoir une précipitation désiré de nitrures et carbo-nitrures dans la microstructure des tubes de reformage, qui sont stables à des températures élevées, c'est-à-dire supérieur à 900°C. However, in the case of alloy types for the production of reforming tubes, the processes mentioned above are rarely used in this respect. Nevertheless, the object of the present invention is to apply nitrogen to have a desired precipitation of nitrides and carbo-nitrides in the microstructure of the reforming tubes, which are stable at high temperatures, i.e. greater than 900 ° C.
Jusqu'à présent il n'était pas connu de traiter la production de tubes en alliage de Fe-Cr-Ni pour le re formage du méthane assistée par de l'azote pour obtenir un contrôle spécifique et optimisé de la microstructure de l'alliage. Until now it was not known to treat the production of Fe-Cr-Ni alloy tubes for nitrogen-assisted methane reforming to obtain a specific and optimized control of the microstructure of the alloy. .
Dans le cadre de l'invention l'utilisation de l'azote pour obtenir un moyen de maîtriser la précipitation de nitrures et de carbo-nitrures dans la microstructure de l'alliage Fe-Ni-Cr avant la coulée du tube de reformage par exemple par centrifugation ou un procédé de fabrication de tubes statique.  In the context of the invention the use of nitrogen to obtain a means of controlling the precipitation of nitrides and carbo-nitrides in the microstructure of the Fe-Ni-Cr alloy before the casting of the reforming tube, for example by centrifugation or a method of manufacturing static tubes.
L'injection du flux gazeux est effectuée au moyen (Figure 3) :  The injection of the gas flow is carried out by means of (FIG. 3):
- d'une lance céramique 1 avec un bouchon poreux en céramique 2, placée dans le centre du pot de raffinage; ou  a ceramic lance 1 with a porous ceramic plug 2 placed in the center of the refining pot; or
- d'un bouchon poreux en céramique et placé dans le fond du pot de raffinage 3 ou sur les parois latérales 4 du pot de raffinage; a porous ceramic plug and placed in the bottom of the refining pot 3 or on the side walls 4 of the refining pot;
- ou d'une combinaison de ces moyens.  - or a combination of these means.
La quantité d'azote à injecter dans l'alliage en fusion est fonction de la composition chimique de l'alliage initial spécifié pour le tube de re formage. L'azote maintenu en excès dans la microstructure finale permettra d'améliorer la résistance au fluage.  The amount of nitrogen to be injected into the molten alloy is a function of the chemical composition of the initial alloy specified for the forming tube. Nitrogen maintained in excess in the final microstructure will improve creep resistance.
Les paramètres à contrôler au cours de l'opération d'injection sont les suivants : le type d'atmosphère autour du métal en fusion dans la chambre de raffinage, le débit d'azote, la température de l'alliage liquide en fusion, la composition chimique et la durée d'injection du flux gazeux. Le contrôle de ces paramètres permettra d'homogénéiser la température et la composition chimique du bain de fusion avec un impact sur la microstructure du produit coulé.  The parameters to be controlled during the injection operation are as follows: the type of atmosphere around the molten metal in the refining chamber, the nitrogen flow rate, the temperature of the molten liquid alloy, the chemical composition and the injection time of the gas stream. The control of these parameters will make it possible to homogenize the temperature and the chemical composition of the melt with an impact on the microstructure of the cast product.
Les tubes de reformage comprenant un alliage selon l'invention peuvent être utilisés pour la production de gaz de synthèse, ou pour la fabrication de fours de traitement thermique.  The reforming tubes comprising an alloy according to the invention can be used for the production of synthesis gas, or for the manufacture of heat treatment furnaces.

Claims

Revendications claims
1. Procédé de fabrication d'un tube pour reformeurs comprenant un alliage de fer, de nickel et de chrome pour tube de reformage comprenant de 20 à 35% en poids de Cr, de 20 à 45% en pois de Ni, et de 0.2 à 0.6% en poids de C, comprenant: A method of manufacturing a reformer tube comprising an alloy of iron, nickel and chromium for a reforming tube comprising from 20 to 35% by weight of Cr, from 20 to 45% by weight of Ni, and from 0.2 0.6% by weight of C, comprising:
- de 0,5 à 2%> en poids de Nb,  from 0.5 to 2% by weight of Nb,
- de 0 à 3%) en poids de W,  from 0 to 3% by weight of W,
- de 0 à 2%> en poids de V,  from 0 to 2% by weight of V,
- de 0 à 1%) en poids de Zr, from 0 to 1% by weight of Zr,
- de 0 à 2% en poids de Mo,  from 0 to 2% by weight of Mo,
- de 0.5 à 2.5% en poids de Si  from 0.5 to 2.5% by weight of Si
- de 0 à P/o en poids de Ti  from 0 to P / o by weight of Ti
- de l'azote entre 0 et 0.5%,  nitrogen between 0 and 0.5%,
- le complément sur 100% en poids étant du fer, the complement on 100% by weight being iron,
caractérisé en ce que :  characterized in that
- l'on injecte avant la coulée de l'alliage en ébullition un flux gazeux exempt d'oxygène et comprenant de l'azote, et  before the casting of the boiling alloy, an oxygen-free gas stream comprising nitrogen is injected, and
- les conditions d'injection du flux gazeux sont choisies de manière à avoir une précipitation des carbures, des nitrures et/ou des carbo-nitrures dans la gamme de 10 à 500 nanomètres.  - The injection conditions of the gas stream are chosen so as to have a precipitation of carbides, nitrides and / or carbo-nitrides in the range of 10 to 500 nanometers.
2. Procédé selon la revendication 1 , caractérisé en ce que l'alliage produit comprend au moins 0,10 et 0,30%) et préférentiellement 0, 1 et 0,2%> en poids d'azote. 2. Method according to claim 1, characterized in that the alloy produced comprises at least 0.10 and 0.30%) and preferably 0, 1 and 0.2% by weight of nitrogen.
3. Procédé selon l'une des revendications 1 ou 2, caractérisé en ce que l'alliage produit est résistant à une température supérieure à 900°C. 3. Method according to one of claims 1 or 2, characterized in that the alloy produced is resistant to a temperature above 900 ° C.
4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que les conditions d'injection du flux gazeux sont choisies de manière à avoir une précipitation des carbures, des nitrures, et/ou des carbo-nitrures, dans la gamme de 20 à 150 nanomètres. 4. Method according to one of claims 1 to 3, characterized in that the injection conditions of the gas stream are chosen so as to have a precipitation of carbides, nitrides, and / or carbo-nitrides, in the range from 20 to 150 nanometers.
5. Procédé selon l'une des revendications 1 à 4, caractérisé en ce que le flux gazeux est injecté sous débit et pression contrôlés, pour vaincre la hauteur hydrostatique du bain en fusion. 5. Method according to one of claims 1 to 4, characterized in that the gas stream is injected under controlled flow and pressure, to overcome the hydrostatic head of the melt.
6. Procédé de fabrication selon l'une des revendications 1 à 5, caractérisé en ce que le flux gazeux est injecté au moyen : 6. Manufacturing process according to one of claims 1 to 5, characterized in that the gas stream is injected by means of:
- d'une lance céramique (1) avec un bouchon poreux en céramique (2), placée dans le centre du pot de raffinage ; ou  - a ceramic lance (1) with a porous ceramic plug (2), placed in the center of the refining pot; or
- d'un bouchon poreux en céramique et placé dans le fond du pot de raffinage (3) ou sur les parois latérales (4) du pot de raffinage ; ou - A porous ceramic plug and placed in the bottom of the refining pot (3) or on the side walls (4) of the refining pot; or
- d'une combinaison de ces moyens.  - a combination of these means.
PCT/FR2014/053450 2013-12-23 2014-12-19 Alloy with stable microstructure for reforming tubes WO2015097379A1 (en)

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EP3589769B1 (en) * 2017-03-03 2021-09-22 Borgwarner Inc. Nickel and chrome based iron alloy having enhanced high temperature oxidation resistance

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