EP0261461B1 - Procédé et appareil pour le traitement thermique de pièces métalliques - Google Patents

Procédé et appareil pour le traitement thermique de pièces métalliques Download PDF

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Publication number
EP0261461B1
EP0261461B1 EP87112804A EP87112804A EP0261461B1 EP 0261461 B1 EP0261461 B1 EP 0261461B1 EP 87112804 A EP87112804 A EP 87112804A EP 87112804 A EP87112804 A EP 87112804A EP 0261461 B1 EP0261461 B1 EP 0261461B1
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EP
European Patent Office
Prior art keywords
furnace
gas
continuous furnace
nitrogen
hot zone
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP87112804A
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German (de)
English (en)
Other versions
EP0261461A3 (en
EP0261461A2 (fr
Inventor
Reinhard Dipl.-Ing. Strigl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Linde GmbH
Original Assignee
Linde GmbH
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Filing date
Publication date
Application filed by Linde GmbH filed Critical Linde GmbH
Priority to AT87112804T priority Critical patent/ATE89868T1/de
Publication of EP0261461A2 publication Critical patent/EP0261461A2/fr
Publication of EP0261461A3 publication Critical patent/EP0261461A3/de
Application granted granted Critical
Publication of EP0261461B1 publication Critical patent/EP0261461B1/fr
Anticipated expiration legal-status Critical
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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
    • 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
    • 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
    • C21D1/76—Adjusting the composition of the atmosphere
    • C21D1/763—Adjusting the composition of the atmosphere using a catalyst

Definitions

  • the invention relates to a method for the heat treatment of metallic workpieces with a gas-heated continuous furnace and under the action of a gas atmosphere which consists essentially of nitrogen and hydrogen and carbon monoxide generated by catalytic conversion of a hydrocarbon immediately before entering the continuous furnace, and a corresponding heat treatment furnace.
  • the heat treatment of metallic workpieces is often carried out in continuous furnaces, to which a treatment gas which is based on the type of heat treatment is supplied from the outside.
  • a treatment gas which is based on the type of heat treatment is supplied from the outside.
  • roller hearth furnaces for annealing semi-finished products made of iron or non-ferrous metals are known, those with so-called exogas that are used in gas generators by exothermic combustion of hydrocarbons with air, or with so-called endogas that are also used in independent gas generators with catalysts - or also within heat treatment furnaces arranged catalytic reactors (see, for example, EP-A 0 180 953 or also DE-A 27 58 024) - is also produced from hydrocarbon-air mixtures with the addition of heat.
  • the treatment gases generated in these processes essentially contain nitrogen, hydrogen and carbon monoxide and, under certain circumstances, also admixtures of carbon dioxide and water vapor.
  • the exact mixing ratio of the components is chosen as it is with the respective type of Heat treatment in the main treatment zone, for example in the hot zone of the continuous furnace, is required.
  • control and regulating methods are known with which the mixing ratio is influenced as a function of a variable measured in the furnace (VDI-Zeitung 98 (1956), No. 24, pages 1486 to 1490).
  • the invention is therefore based on the object of making the known methods for the heat treatment of metallic workpieces in gas-fired continuous furnaces more economical.
  • a nitrogen supply is additionally provided in a process as initially described with internal, catalytic generation of treatment gas, treatment gas consisting of nitrogen, hydrogen and carbon monoxide being supplied to the continuous furnace on the one hand, and nitrogen gas, on the other hand, separated therefrom is fed the treatment gas is fed to the continuous furnace in the region of its heating zone and the nitrogen is introduced at a distance from and on both sides thereof - between the inlet zone and the heating zone and between the heating zone and outlet zone of the continuous furnace - in such a way that the gas atmosphere enters the furnace inlet and the areas adjacent to the furnace outlet contain less than 20% CO and less than 30% H2.
  • a gas atmosphere profile extending in the direction of the longitudinal extension of the continuous furnace is optimally built up, which starts from the furnace inlet with a zone of low reactivity, then reaches the highest reactivity in the region of the hot zone and finally in the region of the furnace outlet drops again to low reactivity.
  • the process according to the invention thus leads to a higher reactivity in the hot zone of the furnace without the furnace atmosphere near the furnace inlet and outlet becoming more toxic or flammable than with exogas.
  • a direct consequence of this procedure is a considerable saving in terms of the consumption of hydrocarbon-containing gases, which can cost up to over 30%.
  • the process according to the invention in addition to the advantage of its increased economic efficiency compared to known processes, also brings about an improvement in the quality, in particular the uniformity, of the treated workpieces, which is based on the fact that the composition of the gas atmosphere at every point in the furnace can be set in an optimal manner.
  • the gas atmosphere formed in the process according to the invention has a high buffering effect against air ingress and leaks in the radiant tube burners. In addition, soot formation and damage to the furnace lining are reliably avoided with the method according to the invention.
  • the ratio between the treatment gas and the separately supplied nitrogen is advantageously chosen so that the furnace atmosphere in the regions adjacent to the furnace inlet and outlet contains even less than 10% carbon monoxide and also less than 10%, hydrogen.
  • the continuous furnace is heated by means of a jet tube burner and the treatment gas is fed to the continuous furnace via a cross section which is arranged concentrically with the burner chamber and at least one of the jet tube burners which is arranged in the region of the hot zone and is filled with catalyst.
  • Preferred areas of application of the method according to the invention are recrystallization and the carbon-neutral or decarburizing annealing of semi-finished products in roller hearth furnaces.
  • a continuous furnace for carrying out the method according to the invention with jet tube burners arranged over its longitudinal extent is advantageously designed such that at least one of the jet tube burners arranged in the area of the hot zone of the continuous furnace has a cross section arranged concentrically with the burner chamber and filled with catalyst for the generation of the treatment gas and in With respect to the longitudinal extent of the continuous furnace, on both sides and at a distance from the one or more jet-tube burners having a cross-section filled with catalyst, gas feeds for nitrogen are arranged in the region between the furnace inlet and the hot zone and in the region between the hot zone and the furnace outlet.
  • the roller hearth furnace 1 has a furnace inlet 2, from which metal workpieces are fed continuously or discontinuously through the furnace 1 to the furnace outlet 3 by means of transport rollers 4.
  • the furnace 1 is heated by a number of radiant tube burners 5 with natural gas as the fuel gas so that the workpieces passing through the furnace 1, e.g. are to be annealed in a carbon-neutral manner, first heated slowly, then reaching the highest temperature approximately in the middle of the furnace and finally slowly cooling the furnace outlet 3 again.
  • a 6 of the jet tube burner 5 is designed as an internally heated catalytic reactor in that the burner chamber is surrounded concentrically by an annular space filled with catalyst for generating the treatment gas. Also owns the furnace 1 has two gas feeds 7 which are arranged in the longitudinal direction of the furnace on both sides of the jet tube burner 6 which is designed as a catalytic reactor. In the case of larger or longer furnaces, several special jet tube burners 6 and / or further gas feeds 7 can also be provided.
  • a natural gas / air mixture is supplied to the jet tube burners 5 for heating.
  • the natural gas / air mixture also becomes the second one Cross-section containing catalyst supplied, where a treatment gas with approximately 40% nitrogen, 38% hydrogen and 18% carbon monoxide is generated by endothermic reaction and is blown into the interior of the furnace 1 by a gas distributor 8.
  • pure nitrogen is introduced via the gas feeds 7 into the furnace 1, which dilutes the treatment gas in the region of the furnace inlet 2 and the furnace outlet 3 so that the gas atmosphere there only contains about 8% hydrogen and also about 8% carbon monoxide.
  • a gas atmosphere profile is built up in this way in furnace 1 over its longitudinal extent, which has its highest reactivity in the hot zone and its lowest reactivity at furnace inlet 2 and at furnace outlet 3.
  • the changing composition of the furnace atmosphere can be caused, on the one hand, by changes in the mixing ratio of the natural gas-air mixture which is fed to the furnace 1 via the jet tube burner 6 designed as a catalytic reactor, and, on the other hand, by changes in the amount of nitrogen introduced into the furnace 1 via the gas feeds 7 can be adapted in any way and extremely precisely to the respective requirements.

Claims (5)

  1. Procédé pour le traitement thermique de pièces métalliques dans un four continu chauffé au gaz soumis à une atmosphère gazeuse, qui est constitué essentiellement d'azote et d'un mélange d'hydrogène et de monoxyde de carbone produit par décomposition catalytique d'un hydrocarbure immédiatement avant l'entrée dans le four continu, dans lequel on introduit, d'une part, dans le four continu, un gaz de traitement constitué d'azote, d'hydrogène et de monoxyde de carbone et, d'autre part et séparément, de l'azote gazeux, dans lequel le gaz de traitement est amené au four continu dans sa zone de chauffage tandis que l'azote est introduit à une certaine distance de cette zone et de part et d'autre de celle-ci entre la zone d'entrée et la zone de chauffage et entre la zone de chauffage et la zone de sortie du four continu, et cela de manière que l'atmosphère gazeuse contienne, dans les zones proches de l'entrée du four et de la sortie du four, moins de 20% de CO et moins de 30% de H₂.
  2. Procédé selon la revendication 1, caractérisé en ce que l'atmosphère gazeuse contient, dans les zones proches de l'entrée et de la sortie du four, moins de 10% de CO et moins de 10% de H₂.
  3. Procédé selon la revendication 1 ou 2, caractérisé en ce que le four continu est chauffé par des brûleurs à tuyères et que le gaz de traitement est amené au four continu, par une section remplie de catalyseur, qui est disposée concentriquement par rapport à l'enceinte de brûleur, d'au moins l'un des brûleurs à tuyères disposés dans la zone chaude.
  4. Procédé selon l'une des revendications 1 à 3, caractérisé en ce que le four continu est chauffé au gaz naturel et que le gaz de traitement est produit au départ d'un mélange d'air et de gaz naturel.
  5. Four continu pour mettre en oeuvre le procédé selon l'une des revendications 1 à 4, avec des brûleurs à tuyères disposés en série sur la longueur du four continu et avec au moins un tube à catalyseur (6) dans la zone chaude du four continu, avec une section remplie de catalyseur et disposée concentriquement par rapport à l'enceinte de brûleur pour la production du gaz de traitement, caractérisé en ce que des alimentations de gaz (7) pour l'azote sont disposées de part et d'autre, et à une certaine distance par rapport au tube à catalyseur (6) sur la longueur du four continu (1), dans la zone entre la sortie du four (2) et la zone chaude ainsi que dans la zone entre la zone chaude et la sortie du four (3).
EP87112804A 1986-09-10 1987-09-02 Procédé et appareil pour le traitement thermique de pièces métalliques Expired - Lifetime EP0261461B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87112804T ATE89868T1 (de) 1986-09-10 1987-09-02 Verfahren und vorrichtung zur waermebehandlung metallischer werkstuecke.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19863630833 DE3630833A1 (de) 1986-09-10 1986-09-10 Verfahren und vorrichtung zur waermebehandlung metallischer werkstuecke
DE3630833 1986-09-10

Publications (3)

Publication Number Publication Date
EP0261461A2 EP0261461A2 (fr) 1988-03-30
EP0261461A3 EP0261461A3 (en) 1989-03-15
EP0261461B1 true EP0261461B1 (fr) 1993-05-26

Family

ID=6309316

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87112804A Expired - Lifetime EP0261461B1 (fr) 1986-09-10 1987-09-02 Procédé et appareil pour le traitement thermique de pièces métalliques

Country Status (5)

Country Link
EP (1) EP0261461B1 (fr)
AT (1) ATE89868T1 (fr)
BR (1) BR8704618A (fr)
DE (2) DE3630833A1 (fr)
ES (1) ES2042524T3 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3842372C2 (de) * 1988-12-16 1996-10-02 Induktionserwaermung Fritz Due Vorrichtung zur Wärmebehandlung metallischer Werkstücke
DE3942810A1 (de) * 1989-12-23 1991-06-27 Linde Ag Verfahren zur bereitstellung und verteilung von behandlungsgas bei waermebehandlungen
DE4016183A1 (de) * 1990-05-19 1991-11-21 Linde Ag Verfahren zur verbesserten bereitstellung von behandlungsgas bei waermebehandlungen
FR2668584B1 (fr) * 1990-10-26 1994-03-18 Lair Liquide Procede d'elaboration d'une atmosphere de traitement thermique et installation de traitement thermique.
DE4343927C1 (de) * 1993-12-22 1995-01-05 Linde Ag Verfahren zur Wärmebehandlung von Werkstücken unter Behandlungsgas
DE19545764C2 (de) * 1995-12-07 2000-02-17 Linde Ag Verfahren zur Schutzgaserzeugung für einen Wärmebehandlungsofen und Wärmebehandlungsanlage
IT1291479B1 (it) * 1997-01-29 1999-01-11 Rivoira Spa Procedimento di trattamento termico di pezzi metallici a base ferrosa in un'atmosfera attiva ad elevato potenziale di carbonio.
DE10347312B3 (de) * 2003-10-08 2005-04-14 Air Liquide Deutschland Gmbh Verfahren zur Wärmebehandlung von Eisenwerkstoffen

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DD31283A (fr) *
DE1433735B1 (de) * 1963-09-21 1969-09-04 Werner Goehring Verfahren zur Erzielung einer Ofenatmosphaere,mit der eine oxydationsfreie Waermebehandlung von Werkstuecken aus Stahl unter gleichzeitiger Beeinflussung des Kohlenstoffgehalts durchfuehrbar ist
DD131292A1 (de) * 1977-03-28 1978-06-14 Arnd Mueller Einrichtung zur schutzgaserzeugung im ofenraum
DE3440876A1 (de) * 1984-11-08 1986-05-15 Linde Ag, 6200 Wiesbaden Verfahren und vorrichtung zum herstellen einer schutzgasatmosphaere

Also Published As

Publication number Publication date
BR8704618A (pt) 1988-04-26
DE3630833A1 (de) 1988-03-17
DE3785989D1 (de) 1993-07-01
ATE89868T1 (de) 1993-06-15
EP0261461A3 (en) 1989-03-15
ES2042524T3 (es) 1993-12-16
EP0261461A2 (fr) 1988-03-30

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